Successful strategies for the modelling of singlet fission chromophores – highly efficient organic materials in solar cells, will be demonstrated on a series of theoretically designed NHC- carbene dimers. All compounds are synthetically feasible and thus suitable for practical application. They differ in topology, conformation, and type of substituents, which allows us, using quantum-chemical methods, to reveal the intimate correlation between structure and excited state properties. Several potential candidates for singlet fission chromophores were discovered in the series. The relationship between molecular conformation and singlet fission propensity is demonstrated for the first time.

This paper aims to highlight the drawbacks of the most common phase locked loop (PLL) circuits to operate as universal PLLs. The phase locked loop tracks the phase of an input signal. These devices are necessary in different disciplines for which the input signal conditions are very different. In fact, they are used in synchronization to the grid waveforms, in the communications applications as frequency modulation or amplitude modulation, and in the measurement of the motors speed, among others. For each discipline, a different group of PLLs is used. Among all of them, the most appropriate to be used in several disciplines seems to be the designed to synchronize the grid. So, they are the chosen to be studied and test their behavior in different applications to find out the PLL which is useful in any application and which achieves to track the phase/frequency signal whose value is initially unknown. I. e. the universal PLL, useful in all the considered applications.

Thus, the most used PLL circuits to synchronize to the grid waveforms, able to work with an unknown initial value of the frequency, have been chosen from the technical literature. I.e. the Synchronous Reference Frame (SRF-PLL), the Second-Order Generalized Integrator (SOGI-PLL), and the Enhanced PLL (EPLL). Their performance has been studied in the monitoring of input signals with conditions different from those presented by the grid voltage, in synchronization. These different conditions are those that occur, for example, in communications applications. The results obtained, prove that the assessed PLLs present a good behavior if the filters and controlled involved in them are tunned to the input signal frequency. In this case, the PLLs provide a signal which tracks the input signal frequency. It could be thought they are universal PLL. However, if the value of the frequency is unknown, the tunning has to be carried out to an estimated frequency, different from the actual one. The results obtained in this paper prove that, in these new conditions, the assessed PLLs do not achieve to track the input signal frequency. Thus, the PLLs analyzed in this paper and carefully chosen are not able to carry out frequency sweeps. Therefore, any of them can be considered as the universal PLL.

Singlet fission (SF) is a photophysical process, occurring in organic materials and having the potential to boost the solar cells’ efficiency. Our study aims at guiding the way for molecular design of compounds, capable of SF. Doping of quinoid structures with Se or/and N-atoms turns out to be a productive strategy for that. Through functionalization and pH modulation, we succeeded to establish rules that link the molecular characteristics to the SF proclivity. Quantum chemical calculations at an appropriate level of theory show that all modelled structures satisfy the conditions, required for a successful fission of singlet excitons.

This paper for the first time proposes methodological frameworks built by generalizing empirical data on the mechanochemical characteristics of materials using interdisciplinary methods. This methodology optimizes research for any composite materials while maintaining targeted research methods and eliminating impractical and related experimental studies with reduced work costs and as a result of environmental impact.

It was recently demonstrated that molecules with low to intermediate diradical character are good candidates for singlet fission chromophores and are therefore promising for photovoltaics application. On the other hand, the diradical character can also be associated with low stability and high reactivity – undesired molecular features for practical utilization. Therefore, in order to reveal the relationship between diradical character – stability – singlet fission propensity, we have performed quantum-mechanical calculations on a series of o- and p-quinone methides. Most of the investigated compounds are reported in the literature and data on their stability and reactivity are available. The study allows us to conclude on the impact of molecular stability on the excited state properties and to explore the compromise between diradical character and singlet fission propensity from stability perspective.

In this paper, we describe the most innovative environmental projects and modular green technology as a key element of our urban spaces and the lungs of the cities. The decision to completely eliminate carbon fuels and reduce environmental pollution, make urban style more sustainable and friendly to the environment is reflected in the use of modular design and technological solutions for the building facades and roofs. A comprehensive analysis of the presented green systems allows to identify their shortcomings and show the advantages of modern modular greening technology using devices that integrate and convert solar and wind energy such as solar panels, micro wind turbines and modern automatic irrigation system. Ergonomic design is provided with the installation in various roof configurations and types such as green and blue roofs and using the system as a vertical gardening by construction of multilevel modular pot system. Another motivating factor will be the deeper appreciation of Green Environmental Protection and the relentless efforts of many governments to this end.

Solar energy which is cheap and present in abundance in tropical and subtropical regions has been universally accepted as future source of energy and photovoltaic cells are considered as potential candidates to harness this energy. In the recent years, India being its proximity to equator has increased the installation of PV systems in a huge way because of the higher irradiation available in large part of the country. India has seasonal variations from extreme cold to scorching heat, sand & dust storms, fog and heavy rain fall during monsoon. All these extreme metrological conditions causes accumulation of soil on PV modules which adversely affect the optimized output of modules. Removing of dust & dirt from the surface of module require cleaning of the module surfaces at regular interval. For this study 12 PV module were selected out of which six were based on mono-crystalline silicon and another six were of poly-crystalline silicon technology of 6 samples each. All the PV modules were made up of 72 cells configuration with 6 rows x 12 columns. Initially, after recording the important parameters such as Voc, Isc, Vmp, Imp, and cell efficiency etc as per manufacturers information the Visual Inspection Test was conducted of all the 12 PV modules as IEC and internal standard protocol. Electroluminescence Test, STC Performance Test, ultrasonic thickness test, reflectance and soiling test were conducted and the data recorded as base data.

To simulate the extreme soiling conditions on the solar PV modules the desert soil which is mostly sandy soil (90-95%) was used. To study the soiling effect the scale of 100 cycles was taken which was further divided into 3 stages, first stage was from 0 to 30 cycle, second stage from 31 to 60 cyles and third stage from 61 to 100 cycles. The desert soil was collected in a cloth bag of fabric with small pores through which fine sand particles were sprinkled manually on the solar PV modules. Initially, for first and second stage the 26 grams of fine desert soil taken in a cloth bag and out of which only 35 to 40% (approx 10gm) soil passes through the pores and accumulated on PV modules. For third stage a bag of 180 gm desert soil was used to sprinkle 50 gm of soil on the surface of test modules. Dry Robotic Cleaning Technology is used for cleaning of the panels. Impact of regular cleaning on panel performance was evaluated by analyzing the effect of cleaning on the glass surface and Anti-reflection coating present on the PV modules. The parameters like; total reflectance, diffuse reflectance and spectral reflectance of light from the module surface were calculated and removal of ARC coating was assessed by performing Ultrasonic Thickness Measurement Test at eight different location of the PV modules.

The present paper proposes an analysis of EU policies related to the enabling of the Distributed Energy Resources  (DERs) participation into the Ancillary Service Market (ASM). Indeed, the rising of renewables and DERs penetration in the power system recently called for the enlargement of the pool of actors that can actively participate in the grid balancing. Therefore, Europe, through directives and guidelines, is gradually fostering the involvement of DERs into the ASM. This paper firstly provides an overview of the regulations actually in place in the EU Member States concerning the participation of DERs into the energy markets. Then, a detailed analysis of the Italian framework is proposed. In the last years, Italy has undertaken a process aimed to increase the observability of DERs, through the installation of suitable monitoring and communication devices, and to enable the provision of ancillary services by dispersed units. The main features and the preliminary results of this process are analyzed and commented, highlighting the benefits and opportunities related to it.

Li-ion batteries are nowadays widely used in electric vehicles, portable devices and smart grids. They are commercialized in different geometries, capacities and serval technologies depending on users’ requirements. During operating time, heat is generated inside Li-ion batteries due to chemical reactions which provides a temperature rise. Non-controllable thermal behavior of these batteries may lead to detoriation of their performance and may cause also a thermal runaway. In this study, A comparison of the thermal behavior of five li-ion batteries is performed. Used batteries are: LFP (lithium iron phosphate) prismatic (72Ah,60Ah,20Ah), NMC (Nickel Manganese Cobalt) prismatic (53Ah) and NMC cylindrical (3Ah). All batteries are tested under different climate conditions and consecutive charge/discharge cycles were applied. The application of consecutive charge/discharge cycles aims to describe the temperature profiles and difference with the ambient in quasi-stationary regime. Constant current was used during each charge/discharge cycle, maximum and minimum voltage recommended by manufactures were chosen as cut of voltage. K-type thermocouples and heat flux sensors are used to measure respectively the temperature and external heat dissipation. The results show a ‘V’ shape during a cycle in quasi-stationary regime for all tested batteries. Moreover, the temperature difference increases for decreasing ambient temperature.

Reducing the consumption of electrical equipment such as air conditioning and lighting in buildings is a challenge around the world. Sensor-based control systems supported by intelligent, adaptive mathematical algorithms can control electrical equipment optimally to save energy and maintain user satisfaction. The system combines PIR sensors, low-consumption temperature and lighting sensors that analyze the characteristics of the environment and allow efficient control decisions to be made in electrical equipment such as air conditioning and lighting system present in the building. This paper presents the design and implementation of the proposed system in a real room and the analysis of the system implementation in a simulation for a building. The simulations of total energy consumption during a period of one year of an occupied building were carried out to verify the performance and energy saving in some scenarios of climatic conditions. The proposed system reduces total energy consumption by 10%.

This paper presents a statistical analysis of the fire hazard of cable lines. Basic properties of cable lines of different types in a fire are specified. Factors affecting the sustainability of cable lines in the event of a fire are identified. An assessment of the sustainability of cable lines in fire conditions in accordance with GOST IEC 60331-21-2011 and GOST IEC 60332-3-22-2011 was made. The results are used for provision of fire safety in buildings and facilities during their operation.

Nowadays, the Web-Of-Cells (WOC) represents an alternative strategy for solving communication, generation and distribution problems in smart grids that integrate Hybrid Renewable Energy Sources (HRES). In this paper a simulation method of WOC architecture with a new voltage control model have been proposed.

The proposed method is summarized in three main points: First modeling of the WOC taking into account the voltage control model has been developed. Then, simulation of the WOC in Matlab/Simulink software is realized. During the simulation of the WOC architecture, profiles of data are considered. Finally, simulation results and explanations are discussed.

The study proved that the integration of voltage control technique in WOC architecture allows optimizing the reverse power flows, local congestions and voltage problems.

The construction industry is one of the major contributors to the CO2 emission which cause environmental impacts on the earth’s climate. Malaysian government is committed in reducing the CO2 by 40% in 2020 and 45% by 2030 as compared to the levels in 2005. Hence, there is a need to reduce the impact on the environment. Currently, Malaysia had developed several assessment tools such MyGHI, pHJKR and Infrastar. However, the implementation was still in not too much. Therefore, the main objective of this paper is to identify the sustainable construction activities element that had been implement and to determine the most main criteria had been implemented in current highway construction project. The pilot study was based on sustainable design and construction activities scorecard in MyGHI. The case studies were chosen based on the stages of the project such as the designing and planning stage, constructing stage, and operating and maintaining stage. The results of the pilot test for case studies had been discussed in focus group discussion. The focus group had been chosen among the expertise in highway development. The experts agreed with all the results that had been gathered during the pilot test. The scorecard of sustainable design and construction activities would be used in the future assessment of highway. The experts had also agreed that highway development in Malaysia is ready for green highway development. All the case studies had gathered 47% until 80% of points. However, the total point scores obtained by different highway projects were considered comparatively and moderately and indicated that the current highway construction practices need to be improved with the sustainable element during highway development. Based on these results, it was clearly discovered that green practices in terms of design and construction were already applied by all three highway projects in Malaysia.

In this paper, we discuss different distortion effects on stability. The analysis of the three different gaps of 0.03C, 0.01C and 0.016C shows that the instability of the fan rotor after the blockage is mainly caused by the inlet distortion. What is more, the blockage is mainly caused by the flow separation of the suction surface of the blade under distortion. Different from the clean inlet flow, leakage vortex in the tip clearance is no longer the main cause.

The main factor affecting the stability of the fan rotor is the inlet flow angle of the leading edge of the fan. The greater the deviation of the airflow angle, the more serious the instability. With the same intensity of distortion, the distortion of the tip position will cause greater instability compared to the distortion away from the tip position. This is because the instability flow at the tip of the blade will evolve in the flow and cause high‐energy irregular flow. In this chapter, this is reflected in the strength of the leading edge overflow. The total pressure distortion causes the deviation of the airflow angle. Then the deviation of the airflow angle causes the leading edge overflow. Overflow at the leading edge causes flow separation of the suction surface, and flow separation of the suction surface causes channel blockage. The channel blockage develops to the end and eventually leads to a stall. Through the comparative analysis of four different circumferential total pressure distortions, the concept of the dynamic disorder is proposed. This method is based on the observation of the unstable flow field, and the author defines the measurement parameters of the degree of unstable flow. The size of this parameter represents the degree of unstable flow.

Soil health and food safety was increasingly advocated, particularly with COVID-19. Improved growth with biochar soil amendment (BSA) through reducing incidence of plant pathogens was addressed as system acquainted resistance. A continuously cropped Alfisol with Chinese Pantax ginseng was amended at 20 t ha-1 respectively with maize (MB) and wood (WB) biochar, compared to manure compost (MC) as control. Annually, mineral (MCF) was supplied at 900 kg ha-1 yr-1 for MC while biochar compound fertilizer (BCF) at 600 kg ha-1 yr-1 for BSA, respectively. With improved survival rate and growth traits, root biomass increased by 25% and 27%, but total ginsenosides unchanged and increased by 10%, respectively under WB and MB compared to MC. Relevantly, bacterial abundance was increased significantly and insignificantly while soil fungal abundance increased by 96.2% and 384.6%. With changes in microbial richness and diversity, community structure both of soil bacteria and fungi was seen altered with biochar amendments. Under WB and MB respectively over MC, abundance of pathogenic Fusarium spp. was significantly decreased by 19% and 35%, in addition to higher abundance of beneficial bacterial species such as Penicillium spp.. And, abundance proportion of pathotrophic fungi to the fungal total significantly decreased while that of Arbuscular mycorrhizal very significantly increased in WB and MB, respectively compared to MC. Thus, BSA and biochar fertilizer, particularly with maize residue biochar, could be a practical measure to improve soil health and ensure growth and functional quality of ginseng roots in continuously cropped fields mainly through improving soil microbiome.

In this work we present an optical analysis for three different hydraulic diameter honeycomb receivers considering the concentrated solar radiation distribution generated by a point-focus concentrator. The analysis was carried out in order to determine the amount of concentrated solar radiation received in it, as well as the shape in which it is received and distributed within the structure, in addition to establishing the length of the receiver itself. The study which determines the location of the receiver on the optical axis of the concentrator is also presented. Ray tracing simulations were done using Tonatiuh considering the physical characteristics of the point-focus concentrator as well as the receiver. As results, it was revealed that around 96% of the concentrator solar radiation arrives to the receiver – inside and in the frontal side-, the rest it attributed to the losses for different factors.

Bio-hydrogenated diesel (BHD) or green diesel is a second generation liquid fuel that can be synthesized through hydrodeoxygenation reaction of fat and its derivatives. It has been expected to replace petroleum diesel and biodiesel due to structure stability and low sulphur. Nevertheless, BHD production still has limitation on the ground of high price for hydrogen feed. Thus, this study report feasibility study of an integrated process of hydrogen production and hydro-processing. The integrated process used refined bleached deodorized palm oil (RBDPO) as a feed. RDBPO was hydrolyzed to produce palm fatty acid (PFA) and glycerol. Glycerol was then fed to sorption-enhanced steam reforming to generate hydrogen gas. After that, bio-hydrogenated diesel was synthesized through hydro-processing between palm fatty acid and hydrogen. The simulation model using ASPEN Plus predicted 57.8 wt.% of overall yield of BHD generated and the integrated process can be self-reliable in hydrogen production without using hydrogen from external sources. Subsequently, production cost and economic profitability of the integrated process were estimated to determine the attractiveness on investment. It was found that total capital investment (TCI) of the production plant was M$25.87 and cost of production $0.52 per litre of BHD. Sensitivity analysis of net present value was conducted after that using three variables, namely RBDPO price, BHD price, and gasoline price. This process was compared with BHD synthesized from fatty acid methyl ester, FAME. At an equivalent capacity, BHD produced from PFA was inferior in term of overall yield, energy consumption and environmental impact.

In this work we present a study on the methane oxidation reaction on Cr2O3 in the presence of sulfur dioxide using both infrared spectroscopy and simulations based on the density functional theory. The purpose of the work is to know the reasons why sulfur dioxide decreases the activation energy of the methane oxidation reaction. We found that sulfur dioxide promotes oxygen dissociation through the formation of sulfite species. Dissociated oxygen favors the dehydrogenation of methane, the formation of methoxy species, formaldehyde, dioxymethylene, and methanol.

The report addresses the thermodynamic analysis of the electrochemical process of hydrogen and oxygen high-pressure generation. This process can improve the energy efficiency of the membraneless electrolysis method.

The method is based on the use of a gas-absorbing electrode with a highly developed contact surface between the electrode and electrolyte. The electrochemical activity of the gas-absorbing electrode material (Fe(g)) is higher than that of platinum-coated electrodes and exceeds them in the efficiency of the electrolysis process. The electricity consumption required for the production of hydrogen and oxygen is in the range of 3.95 kWh/m3 to 4.16 kWh/m.3 It should also be noted that this process is cyclic, consisting of a half-cycle of hydrogen evolution and a half-cycle of oxygen evolution. The distribution of the energy consumption by half-cycles is 0.88 kW h / m3 per H2 ↑; 3.28 kW h / m3 on O2 ↑ respectively. The material of the gas-absorbing electrode (Fe (g)) chemically binds the oxygen when it acts as the anode, while the hydrogen is evolved at the cathode (Ni). The reverse of the polarity allows the hydrogen to be chemically bound by the cathode material (Fe (g)) and the oxygen gas to be evolved at the anode (Ni). The cyclic operation of the electrochemical cell makes it possible to stop the usage of proton-exchange membranes, which results in a significant increase in the operating pressure of the generated gases (up to P = 20.0 MPa). This pressure is achieved not because of the use of compressor equipment, but due to the isochoric process of electrochemical production of high-pressure hydrogen and oxygen. The above advantages contribute to the successful implementation of an innovative electrolyzer as an element of a buffer storage system for a secondary energy carrier (hydrogen) in energy technology complexes using alternative energy sources.

Third-generation thin-film solar cells based on CZTSSe are highly promising because of their excellent optoelectrical properties, earth-abundant, and non-toxicity of its constituent elements. In this work, the performance of CZTSSe based solar cells with TiO2, CdS, and ZnSe as electron transporting materials (ETMs) was numerically investigated using the Solar Cell capacitance Simulator (SCAPS). The effect of the active layer’s thickness and electron affinity, different buffer layers and the contour plot of the operating temperature versus thickness of the CdS buffer layer were studied. The results show that the optimum power conversion efficiency for CdS, TiO2 and ZnSe, as the ETMs, is 23.16%, 23.13%, and 22.42%, respectively.

While the global water resource is very limited, the rapid population growth and urbanization have caused an added demand for fresh water. The developing capacitive deionization (CDI) method has gained extensive attention mainly due to its high energy-efficiency, environmental friendly, and low cost for desalination. To improve the benefits of flow-electrode CDI (FCDI) and the simplicity of the traditional flow-by CDI methods, a novel fluidized CDI (FdCDI) has been developed. In this work, a feasible study for FdCDI of saltwater using the thin stainless steel (SS) as the current collectors was investigated. The less resistance graphite current collectors for the FdCDI electrodes without activated carbon (AC) coating have a greater salt adsorption capacity than that of the SS ones. Moreover, the graphite current collectors possess a nearly ideal capacitor behavior and allow the ions in the solution to be more efficiently electrosorbed by the electric double layer of flow electrodes. Nevertheless, the cyclic voltammetry (CV) curves of the AC-coated SS and graphite electrodes have a near rectangle shape for the charge/discharge process, which can be regarded as supercapacitors at a scan rate of 5-25 mV/s. The shape of the curve is similar, indicating that less resistance causes the ions to transport fast in the microporous electrodes. The thin SS become a better current collector simply due to the fact of the more feed rates (by +85%) can be achieved for FdCDI.

The tailings of arsenic-containing gold ores have caused a serious environmental problem in the north of Taiwan. Electrokinetic remediation (EKR) is one of the feasible methods for in situ soil decontamination. Although EKR has been proven to be very feasible in laboratory- and bench-scale experiments and small-scale field tests, an understanding of the complex arsenic involved in the EKR is of great importance. Thus, the main objective of this work was to track the fate of arsenic in the gold tailing by in situ EXAFS spectroscopy. By XRD, it is clear that As2O3 is the main arsenic compound in the gold tailing. After EKR, the arsenic concentration near the anode is greater than that near the cathode in the arsenic-containing tailing. The first derivative feature of XANES spectra appeared at 11870 eV indicates the existence of As2O3 that is the main arsenic compound in the arsenic-containing gold tailing. Prolonging the EKR contact time to 90 min, the bond distances of As-O (1st shell) and As-As (2nd shell) are increased slightly, that is attributed to the perturbation by the electric field. Note that the dissolved H2AsO3- is accumulated near the anode. The amount of As2O3 (dissolved as H2AsO3-) in the tailing is increased significantly after EKR for 60 min. However, when the EKR time was prolonged to 90 minutes, the amount of H2AsO3- is decreased, suggesting the migration of arsenic to the anode and eventually accumulated near the anode. This work illustrates the usefulness of EXAFS and XANES for revealing speciation of arsenic embedded in the complex matrix of a gold tailing in the EKR process.

Electricity markets are becoming a popular field of research amongst academics because of the lack of appropriate models for describing electricity price behavior and pricing derivatives instruments. Models for price dynamics must consider seasonality and spiky behavior of jumps which seem hard to model by standard jump process. Without good models for electricity price dynamics, it is difficult to think about good models for futures, forward, swaps, and option pricing. In this paper, we attempt to introduce an algorithm for pricing derivatives to intuition from the Colombian electricity market. The main ambition of this study is fourfold: 1) First we begin our approach through to simple stochastic models for electricity pricing. 2) Next, we derive analytical formulas for the prices of electricity derivatives with different derivatives tools. 3) Then we extent short of the model for price risk in the electricity spot market 4) Finally we construct the model estimation under the physical measures for the Colombian electricity market. And this paper ends with a conclusion.

In this paper, we are interested to explore stable configurations of d-dimensional gravastars constructed from the interior d-dimensional de Sitter and exterior d-dimensional black holes through cut and paste approach. We consider linearized radial perturbation preserving the original symmetries to explore their stability by using three different types of matter distributions. It turns out that the resulting frameworks represent unstable structures for barotropic, Chaplygin and phantomlike models for every considered choice of exterior geometries. However, matter contents with variable equations of state have remarkable role to maintain the stability of gravastars. We conclude that stable structures of gravastars are obtained only for generalized variable models with exterior d-dimensional black holes.

Global warming has been proved to be caused by the excessive emissions of CO2 from the usage of fossil fuels. Therefore, promoting carbon mitigation strategies and energy transition are of increasing importance. Reduction of CO2 to C1 fuels by solar energy like artificial photosynthesis is thus environmentally attractive and close the carbon cycle. There are still major challenges such as low conversion efficiency and high recombination of electron-holes during photocatalytic reduction of CO2. We have developed novel perovskite quantum dots (PQDs) encapsulated within metal organic frameworks (MOFs) (PQD@MOF) composite for dual photoelectrodes to proceed the high-efficiency photocatalytic reduction of CO2. By the PQD@MOF under visible-light irradiation, about 500 μmol C1/mgCat/h were obtained. It is apparent that the novel PQD@MOF photocatalysts are chemically feasible for solar-driven CO2 reduction to C1 fuels.

The problems of optimal control of a trajectory construction for mechanical system motions and optimization of production process behavior represent the most advanced parts of the mathematic (nonlinear) programming theory. It consists of classical methods of differential and variational calculuses elaborated by L. Euler and J. Lagrange and advanced in works of R. Bellman, L. Pontryagin, and their disciples. In the implicit form, the optimization problems emerge in the petroleum engineering concerned with design and construction of deep curvilinear oil and gas boreholes. Now, drilling and completing the boreholes with complicated geometry, large lengths, and in heterogeneous geostructures with aims to improve their production while saving time and material expenses are becoming commonplace. Not rarely, they are accompanied by risks of emergency situations and failures. The pointed aggregate of factors associated with the geometry of a borehole trajectory connecting its initial and terminal ends, its tortuosity influencing on contact, friction, and resistance forces, as well as, requirements of its length and cost minimization, is the main stimulus prompting to the use of optimal control methods for the optimal tracking of the borehole trajectories.

In modern oil/gas producing industry, vertical, 2D and 3D directed, and multilateral (branched) boreholes are drilled. Their trajectories are designed depending on the petroleum deposit depth and structure, properties of mining rocks, their hardness, heterogeneity, fracturing anisotropy, permeability, and so on. Therefore, the borehole cost and its productivity are determined by the length, smoothness, and configuration of its trajectory. To enhance efficiency of a borehole and to reduce cost of its drivage, to enlarge rate and volume of the reservoir depletion, it is firstly proposed to use methods of optimal control for the best tracking of its trajectory.

The objective functionals chosen as integral curvature, length or cost of the borehole are considered. The techniques for the optimization problem solving are developed with the use of the continuous version of the step-by-step antigradient projection on the hyperplanes of linearized constraints.

Some examples are considered for a borehole with fixed and shifting boundary positions under conditions of minimizing its total curvature and length. It is shown that it is possible to improve the smoothness of the borehole trajectory using the outlined approach, and in so doing, reduce the friction and resistance forces impeding the drill string motion.

Exclusive advantage of the proposed approach can be achieved as applied to optimization of 3D and multilateral (branching) borehole trajectories in complex rocks. To state these problems, it is necessary to pose multipoint boundary value problems for ordinary differential equations and to solve multipoint problems of optimal control that are connected with additional (but soluble) difficulties. Statement and solution of these problems is a real art.

The structural and electronic properties of hexagonal boron nitride (h-BN) sheet implanted with X atoms (X=Li, Be, Al, C and Si) have been investigated to tune its band-gap to amend its insulating behaviour towards semi-conducting material employing density functional theory (DFT). It has been observed that on replacing nitrogen or boron (N/B) atom with impurity atom(s), several impurity levels appear in band gap dividing big gap into small energy gaps, albeit to different extent, depending upon the dopant element and subsitutional site. The lowest value falls as low as 2.27 eV as compared to 4.63 eV of pristine h-BN in addition to appearance of states at Fermi level. Additionally; geometrical, interaction of foreign elements with the host material and stability issues are discussed. These results are affable for its usage in transistor-based devices and to explore its new applications in high-power electronic and optoelectronic devices.

A better understanding of CO2 adsorption on the one-dimensional TiO2 nanotube (TiNT) is of great importance for improving its photocatalytic reduction ability. In this work, adsorption and photocatalytic reduction of CO2 on the TiNT was studied by in situ FTIR. The IR absorbance features at 1303 and 1393 cm-1 are associated with carbonate species, e.g., bidentate carbonate on the TiNT. Complete desorption of CO2 from the TiNTs may occur at T>418 K. The in situ FTIR studies indicate bidentate carbonate and carboxylate species on the TiNTs, which may conduct the surface reactions enhanced by UV/Vis light to yield of low carbon fuels or chemicals.

There is a lack of quality data on the levels of polycyclic aromatic hydrocarbons (PAHs) in incineration fly ashes primarily due to the conventional Soxhlet extraction fails by the recovery of PAHs during the process. To better understand the hindered PAH finger-print patterns in the fly ashes, extractions with supercritical fluids (SCFs) such as dichloromethane (SDCM) (Tc=333 K and Pc=248 bar), water (SCW) (Tc=673 K and Pc=240 bar), and CO2 (SCCO2) (Tc=333 K and Pc=248 bar) were studied. By adjusting the dielectric constant (ε) of the supercritical fluids and mixtures, moderate-to-low polarity PAHs in the fly ashes can be extracted. Virtually most of PAHs hindered in fly ashes can be quantitatively extracted with the supercritical fluids at a wide range of ε. Moreover, the adjustable-ε SCF method developed in this work may have promising applications in the analysis of deuterated-PAHs embedded in interplanetary dusts.

Desulfurization of syngas containing H2S at high temperatures for integrated gasification combined cycle is gaining momentum as a commercially viable source of clean energy. Thus, a feasibility study for hot-gas (1% H2S) desulfurization by ZnO on skeletal Raney CuO (ZnO/R-CuO) absorbent was carried out. The degree of the hot-gas desulfurization by ZnO/R-CuO was 90.0% at 873 K and decrease to 46.5% as the temperature raised to 1073 K. The rate constant (k) for the desulfurization by ZnO/R-CuO at 873 K was 8.35×104 cm3/min g with the activation energy (Ea) of 114.8 kJ/mol. Speciation of zinc and CuO in the ZnO/R-CuO for the hot-gas desulfurization was also studied by synchrotron X-ray absorption near edge structure (XANES) spectroscopy. Mainly Zn(II) and Cu(II) were found in the ZnO/R-CuO. By EXAFS, in the 2nd shells, a decrease of Cu-Cu bond distance in ZnO/R-CuO was observed during desulfurization. However, an increase in Zn-Zn bond distance was observed after desulfurization. It is apparent that hot-gas desulfurization by ZnO/Raney CuO absorbent is chemical feasible.

Wind energy is undoubtedly an essential generation source required to achieve a transformative renewable energy supply portfolio. However, long-term sustainable wind energy deployment faces various challenges due to various complex interconnected impediment factors. These inherent endogenous and exogenous uncertainties preclude obtaining an accurate future trend, which complicates the design of a good policy. This study seeks to critically identify all the involved parameters that contribute to the future of wind energy in Iran. In doing so, the research employs Fuzzy Cognitive Maps to analyse the relationship and role of each determined element within the system. The research outcome revealed 26 influential factors shaping the dynamics of the system in six main categories (PESTEL). The findings demonstrated that Iran’s wind sector is predominated by economic and political drivers with strong interconnections. Five key concepts, including two economic, one legal, and two political, were ascertained that contribute to the system’s stability.

The (Ni/ZnO)@C core-shell nanoparticles were prepared by carbonization of Ni2+- and Zn2+-cyclodextrin complexes at 723 K for 2 h. ZnO and Ni encapsulated in carbon-shell were etched partially to form the (Ni/ZnO)@C yolk-shell nanoreactors for photocatalytic reduction of CO2 to C1 fuels. By XRD, it is clear that ZnO is the main zinc crystallite in the nanoreactors, and its nanoparticle size is between 10-20 nm. The TEM images of the nanoreactors indicate that Ni and ZnO having the nanosizes of 5-30 nm are capsulated in the porous carbon-shell that allows molecules to diffuse in and out for photocatalytic reduction of CO2 to C1 fuels. It is worth noting that ZnO in the (Ni/ZnO)@C yolk-shell nanoreactor plays the main photoactive role in photocatalytic degradation of methylene blue. However, excess Ni encapsulated in carbon-shell leads to a de-activity in photocatalytic degradation of MB and reduction of CO2. By in situ FTIR spectroscopy, the disappearance of CO2 is at the expense of formation of species containing CH and carbonyl groups, possibly related to yields of C1 species such as HCOOH.

Reservoirs at Mingebrak Basin in Uzbekistan are characterized by big burial depth (5200- 6500m), high temperature (150-200℃), high pressure (pressure coefficient 2.08-2.41), high salt content (220000mg/l), and high H2S content (5~6%) in the formation fluid. The Musgothic formation is especially complex because it contains different pressure systems. Leakage and blowout are easy to occur during well drilling and the average drilling period is 732 days. The data of well drilling history have been analyzed and the causes of the long drilling period have been detected. The results showed that the drilling problems in the Musgothic formation was the main cause of the non-drilling time because leakage and overflow occurred frequently and time was consumed in dealing with leakage and overflow. Three methods have been taken to conquer the drilling problems: finding out the setting positions and improving the wellbore structure; selecting the organic salt drilling fluid and optimizing the formula of it through experiments; developing different lost circulation materials to bridge different types of leakage.

Leakage prevention and control technologies have been worked out through analysis and experiments. Firstly, the mudstone at the top of Musgothic and the high-pressure formation at bottom of Musgothic were taken as setting positions respectively and the wellbore structure was improved from three-hole structure to four-hole or five-hole structure. Secondly, an organic salt drilling fluid formula with temperature resistance of 180℃, salt contamination resistance of 30%NaCl and 1% gypsum, and 93.48% recycle rate was developed. Thirdly, three types of loss control materials: return loss control materials, fracture loss control materials, and permeable leakage control materials were developed to deal with different types of formation leakage. The three methods, five-hole wellbore structure, high temperature organic salt drilling fluid and 840 m3 loss control materials have been uccessfully used in an exploration well M15 in Mingebrak Oilfield, and the drilling period was only 390 days, only about a half of the average drilling period in this area. The study of the mud loss prevention and control technologies of this paper is significant for reducing the drilling period in Mingebrak Oilfield, Uzbekistan. Their successful application in well M15 set a good example for safe and fast drilling of deep wells in this oilfield and the technologies will be popularized for application in other wells of this area. 

Recycling of rare precious metals (RPMs) from E-waste by traditional methods such as pyrometallurgy and hydrometallurgy are generally high energy consumption, cost, and risk of environmental pollution. In this study, fluid capacitive deionization (FdCDI) process was used to concentrate the RPMs from a wastewater. The solar-driven photoelectrocatalytic (PEC) reduction of RPM ions (such as Au3+ and La3+) to metals was investigated. Electrons jumped to an excited state by solar energy can be transferred to photocathode through the external circuit to generate electricity in the PEC-I. In the solar-driven PEC-II on the photoanode, the photo-generated electrons can cause the reduction of RPM ions to metals. The speciation of gold and lanthanum during the FdCDI processes was determined by X-ray absorption near structure (XANES) spectroscopy for a better understanding of their electronic structure and oxidation states during photoelectrocatalysis, their synchrotron extended X-ray absorption fine structure (EXAFS) spectra were also determined for an improvement of the photoelectrocatalysts.

This paper is dedicated to a new technique for advances in the study of the main parameters of flight and monitoring of nocturnal migration of birds. The Electronic-Optical Matrix System allows us to detect and record aerial targets in the night sky of a size greater than 5 cm and at an altitude of 100 to 1000 meters a.g.l. The principle design features are:- (1) An optical device for receiving images of flying targets on three high-sensitivity CCD matrices when illuminated by infrared light from searchlight beams and (2) Instantaneous parallactic computation enabling the distance from device to target to be accurately measured, and sequential images of each target to be recorded to computer. The device has been tested on song birds during seasonal nocturnal migration and provides accurate image details of important target flight parameters including: altitude, linear size (wing span and body length), direction of flight – track, orientation of the body axis – heading, ground and air speed, wing-beat frequency, number of wing-beats in each series of beats, duration of the pause between cycles of wing-beats, and type of flight trajectory. Special attention was given to one of the major difficulties in research of bird migration – the potential for the identification of individual species of birds flying in the night sky by combination of the recorded flight parameters. There are also the potential practical applications for aviation bird-strike at night as well as the remote monitoring of insects, bats and other targets of natural and artificial origin.

Conversion of CO2 to low-carbon fuels using solar energy is considered an economically attractive and environmental friend route. The development of novel catalysts and the use of solar energy via photocatalysis is the key to achieve the goal of chemically reducing CO2 under mild conditions. Thus, in this study, the novel Cu2O/TiO2 heterojunctions were used for CO2-to-low-carbon fuels. The p-n heterojunction is able to enhance the separation of photogenerated electron-hole pairs. By UV-vis diffuse reflection absorption spectroscopy, it is clear that Cu2O coupled with TiO2 causes a red-shift to the visible light range. Under a 6-h UV-vis irradiation, 12.4-70.6 µmol methanol/g-catalyst can be generated by the Cu2O/TiO2 heterojunctions. However, excess Cu2O in the Cu2O/TiO2 heterojunctions may cause less absorption of UV-vis light and decrease the excited electrons from TiO2, which may obstruct the photoactivity for reduction of CO2.

Malaysia relies heavily on fossil fuels such as coal and natural gas as its main source for electricity generation. Decades of exploitation and usage of these materials had not only caused contamination and depletion but also contributed to the large amount of carbon dioxide emission in the country. In 2015, Malaysia has signed the Paris Agreement and vowed to achieve the reduction of carbon dioxide emission by 45% per GDP to the level of 2005 by 2030. Prior to the Fukushima accident that happened in 2011, Malaysia has had plan to own a 2GW nuclear power plant by 2030. However, this plan was then delayed and now cancelled after the Fukushima accident. The importance of this research is to examine the changes in the environment and economy of Malaysia by adding nuclear power and renewables into its energy mix. Carbon dioxide emission trend will be determined and an economic analysis will be conducted. This research intends to draw a best-fit scenario for Malaysia to have a new energy mix that can achieve in the 45% carbon dioxide reduction. This research will be helpful for the Malaysia government as a reference to plan for its future energy production system.

To reduce the cost of a dye-sensitized solar cell (DSSC), noble metal platinum (Pt) on the counter-electrode has been replaced with relatively cheap metals, i.e., photo-activity-designable bimetal core-shell nanoparticles. In present work, nickel and iron encapsulated within carbon-shell (FeNi3@C) nanoparticles were prepared by carbonization of Ni2+ and Fe3+-β-cyclodextrin at 673 K for the DSSC counter-electrode. By component fitted X-ray absorption near-edge structure (XANES) spectroscopy, metallic nickel (Ni) and iron (Fe (73%) and Fe3O4 (27%)) are observed in the FeNi3@C. The FeNi3@C nanoparticles are deposited on a conductivity glass recovered from thin film transistor (TFT) liquid crystal display wastes for the counter-electrode of a DSSC. The DSSC having the FeNi3@C nanoparticles coated counter-electrode has the conversion efficiencies of 3.1%. In addition, the cost of the DSSC using the reccycled conducing glass and cheaper nanostructured FeNi3@C electrode can be reduced by at least 38%.

Water splitting to hydrogen and oxygen through a four-electron transport route has been widely studied for hydrogen energy. Alternatively, H2O can photocatalytically yield H2 and H2O2 (2H2O → H2(g) + H2O2(aq)) through a two-electron reaction that is more kinetically feasible. The naturally separated H2O2 aqueous solution from gaseous H2 can be directly utilized in oxidation of organic pollutants in wastewater. In this work, NiP dispersed bismuth oxyiodide (BiOI) and graphite carbon nitride (gC3N4) composites were prepared for photoelectrodes to yield H2O2. And other transition metal phosphide such as CoP with BiOI-gC3N4 was also used to enhance the solar driven H2O-to-H2O2 reactivity. As the NiP and CoP dispersed BiOI-gC3N4 composite are very effective for H2O2 yields, it would be very useful for the feed of a H2O2 fuel cell for electricity.

This work reports the performance enhancement of lead free perovskite solar cell (PSC) with Sb2S3 as a novel hole transport layer (HTL) numerically by using Solar Cell Capacitance Simulator in One Dimensional (SCAPS-1D). Three different HTLs such as Sb2S3, Spiro-OMeTAD, and CuI are introduced into the conventional CH3NH3SnI3-based solar cell configuration consisting of Al/FTO/WS2/CH3NH3SnI3/Sb2S3 or Spiro-OMeTAD or CuI/Ni. The photovoltaic performances of the lead free perovskite solar cells with the proposed HTLs are evaluated extensively and compared using the SCAPS-1D simulation tool. The impacts of thickness, defect density, acceptor density of perovskite absorber and valance band offset at HTL/perovskite interface on the device performance parameters are analyzed. The variation of working temperature on the PSC outputs is also investigated to realize the stability of the proposed PSC with Sb2S3 HTL. The thicknesses of the WS2 electron transport layer (ETL), CH3NH3SnI3 absorber, and Sb2S3 HTL are optimized to be 0.05 m, 0.7 m, and 0.1 m, respectively. The improved power conversion efficiency is achieved to be 27.29% for the optimized solar cell structure of Al/FTO/WS2/CH3NH3SnI3/Sb2S3/Ni, while the efficiencies of 25.65% and 21.21% are obtained for the lead free the PSCs with Spiro-OMeTAD and CuI HTLs, respectively. Based on the overall investigation and simulation results of the proposed device, it is predicted that WS2 as ETL and Sb2S3 as HTL would be very promising for enhancing the performance of the lead free tin-based PSC, and it would provide constructive research opportunities for the designers to fabricate low-cost lead-free PSCs.

Lithium-ion battery (LIB) are widely used in electronic products and electric vehicles largely due to the advantages of low price, low memory effect, high power efficiency, and long life cycle. In recent years, an increasing amount of end-of-life LIBs are to be recycled. Extraction of spent LIB has been carried out for recycling of valuable metals such as cobalt. Environmental friendly organic acids such as citric acid was used to selectively extract cobalt. For a better understanding of the cobalt speciation during extraction, in situ synchrotron extended X-ray absorption fine structure (EXAFS) spectra at 323-363 K. Specifically, H2O2 (0-1%) was added during the extraction to obtain desired Co3+/Co2+ ratios that also facilitate the extraction efficiency.

Heritage Buildings are significant of their historical and architecture added value, which require in deep and precise preliminary brainstorming when considering upgrade or retrofitting of these valuable buildings. This study opts to spotlight on some passive design architecture interventions to improve the thermal comfort and the required cooling energy for the building. The Murabaa Palace in Riyadh was selected as a case study. The design builder software was used to evaluate the energy performance of four passive architectural design alternatives. The results show that using Low-E double glass in addition to applying double wall with polystyrene thermal insulation can enhance the thermal comfort inside the building and reduce the energy performance and CO2 emissions to 17% and 9% respectively.

Most of non-recyclable municipal solid wastes have been treated by incineration for energy recovery and stabilization. However, the fly ash (FA) discharged from air pollution control devices contains toxic metals and chlorides as well as leachable dioxins that make it considered as hazardous wastes. Chlorides in FA that was washed with water can be removed by electrosorption using the new fluidized capacitive deionization (FdCDI) method. Ions including Cl- in water can be stored in the electrical double layer (EDL) of electrodes, and deionized water (<50 mg/L) can be recycled and reuse under low voltages (0.8-1.2 V). Note that the regeneration of FdCDI can be achieved by applying a zero or reversed voltage. In the FdCDI process, no chemical is needed, resulting no sludge to be discharged and treated. In addition, the effects of Cl- counter ions during FdCDI was also studied. The Cl- removal efficiency (51% approximately) with the salt adsorption capacity of 10 mg /g was obtained in the FdCDI process. This work illustrates that fly ash can be dechlorided by the FdCDI method for utilization such as civil engineering fillers.

In the quest of new source of renewable energy source, perovskite have shown promising breakthroughs as a third generation low-cost solution based thin-film photovoltaic (PV) technology. High power conversion efficiency (PCE) from 3.8% in 2006 to 25.2% in 2019 for organic-inorganic hybrid perovskite based PV devices has been achieved. But the drawbacks of hybrid perovskites most of them are lead based, which is toxic and also organic cations are instable. On the other hand, most inorganic perovskites (such as Sn, Ag, Sb, Bi, Cu) are not suitable as they possess large band gaps around 2 eV, furthermore, it has low open circuit voltage, unstable cation and poor charge transport features (Sn+2, Ge+2, Bi+). To overcome limitations, many new types of stable inorganic perovskite have been introduced, such as Cs2TiBr6, Cs2TiI6, Cs2TiF6, and Cs2TiCl6. However, they have poor PCE ranging from 3 to 7% because of high band gap which absorbs a narrow spectrum of high energy photon. Among these new perovskite materials, Cs2TiI6 has the band gap of about 1.8 eV which is logically more likely to absorb less photon energy than other PSC devices.

In this study, numerical simulation has been performed using Solar Cell Capacitance Simulator-1D (SCAPS-1D) software to analyze the performance of Cesium Titanium (IV) Iodide thin film based lead-free perovskite solar cell (PSC). In this research work, three different Hole Transport Layers (NiOx, MoS2 and Cu2O) are examined with the same perovskite absorber layer and common Electron Transport Layer (ETL). Proposed device configuration for this work is Carbon/NiOx or MoS2 or Cu2O/Cs2TiI6/TiO2/FTO/Glass. Power conversion efficiency (PCE) for NiOx, MoS2 and Cu2O employing designs are found to be 13.05%, 12.68% and 14.41%, respectively, where the previous work having the same absorber layer have reported the power conversion efficiency to be 3.13% [5]. In this work, absorber layer thickness have been optimized for all three configurations, as well as the influence of changing operating temperature, defect tolerance and changing series and shunt resistance on perovskite solar cell (PSC) devices have also been investigated. Main goal of this research is to find a high band gap PSC for utilizing in tandem solar cells, in order to enhance overall efficiency by absorbing shorter wavelength portions of the spectrum (high energy photon), which usually remain unused in traditional solar cells.

In order to improve the thermal efficiency and outlet temperature of the larger-aperture parabolic trough concentrator (PTC) solar power, a three-stage heating technology is proposed. The single loop, composed of a semicircular absorber tube (AT) with two outer fins, a semicircular AT and a circular AT, makes the temperature rise from 300℃ to 580℃, and it operates safely under the maximum temperature of 600 ℃. The results show that the optical efficiency is 79.1%. The thermal efficiency are 64.3% (DNI = 400W/m2), 69.1% (DNI=600W/m2), 71.4% (DNI=800W/m2) and 72.8% (DNI=1000W/m2), respectively. The length of the single loop is about 1400m and the flow mass rate is 6.1kg/s-19.9kg/s corresponding to DNI of 400W/m2-100W/m2 to meet the requirement of the larger-aperture PTC system temperature. In the low temperature range of 300℃-400℃, the thermal and optical efficiency are the highest and the required length is the shortest. In contrast, the optical and thermal efficiency are the lowest and the required length is the largest in the high temperature range (500℃-580℃). Thermal efficiency in the high-temperature section is about 21% lower than that in the low temperature. By homogenizing the solar radiation flux on the absorber tube (AT) in the high temperature section, the flow mass rate and the AT’s length can be reduced, which could improve the thermal efficiency.

Several models have been developed and these models now provide a good understanding of how VRB works. This knowledge is very important to evaluate its performance when applied in an electrical system. This article presents a new VRB model based an electrical equivalent model of VRFB, the effect of flow rate and pump power losses has been considered in modeling the VRFB. The VRFB is connected to a resistive variable load, for discharging and a systeme PV for charging. A control method for State of Charge (SOC) estimation is also proposed as it plays an important role in over-charge/discharge of VRFB. An equivalent electrical model of PV system including a VRB was implemented in MATLAB/Simulink environment to analyze the operational performance of the proposed system.

Scrap tires containing metal wires, fibers, carbon black, and poor thermal conducting rubbers, are far more difficult to be treated effectively. Million fuel oil equivalent are discarded every year through the disposal of scrap tires. Recycling of scrap tires is of increasing importance as incineration and landfilling becomes expensive, and the acceptance of these methods is decreasing. The feasibility for recycling of product oils, metal wires, and carbon black from liquefaction of scrap tires was thus investigated in the present work. The liquefaction process involves contacting the scrap tires (5-15 cm pieces) with hot used motor oil in an inclined screw reactor. Liquefaction of scrap tires at 643 K for 20 min yielded approximately oils (90%), non-condensable gases (5%), and non-liquefiable solid residues (metal wires and fibers) (5%). In the liquefaction process, ZnO (original in tire rubber) could be sulfurized with the tire rubber cross-linked sulfur, and a significant decrease of the sulfur concentration in the product oil and flue gas streams was found. Fuel oils, clean metal wires and fibers, and dry carbon black were recycled. In addition, the flue gas was used for keeping the circulated hot motor oil at 643 K. The bench-scale inclined screw liquefaction reactors suggest that the tire liquefaction process is technically feasible.

This paper provides an appropriate technological intervention with a zero-carbon footprint operating model while converting a dangerous forest bio-residue into a usable commodity. In our study, the dangerous forest bio-residue consists of the dry and fallen pine needles of the trees that grow in the Western Himalayan region. The appropriate technological intervention is the evolution of a manually operated biomass briquetting machine, and the usable commodity is the bio-briquettes, which could be used as an alternative to fossil fuels. Dry and fallen pine needles induce devastating forest fires in the Himalayan region, which facilitates the release of huge amounts of carbon into the atmosphere without obtaining any productive use from it. The purpose of this research is to present an easy-to-operate manual intervention to densify the loose and dry bio-residue into a useful and salable fuel option while promoting community involvement. The studies propelling the evolution of the briquetting machine are based on reflexivity, where communities themselves have been demanding such types of basic and indigenous interventions to create reasonable livelihood options for themselves and to address the socio-climatic issues caused by forest fires in the Himalayan region.

Nowadays, organic-inorganic hybrid perovskite solar cells (PSCs) with fascinating optoelectronic properties have attracted remarkable attention in photovoltaic devices. However, their instability under ambient conditions is one of the major limitations of practical implementation. Recently, it has been reported that the formation of a 2D alkylammonium halide perovskite layer on the 3D film can passivate interfacial defects and vacancies and improve the stability of PSCs. In this study, p-Phenylenediaminium iodide (PDAI) is used to in-situ growth of 2D (PDA)2PbI4 perovskite layer between (FAPbI3)0.85(MAPbBr3)0.15 3D perovskite and CuSCN. The results indicate that the incorporation of PDAI leads to enlarged grain sizes, compact grain boundaries, reduced trap density, efficient charge extraction, and enhanced stability of perovskite film. Passivation of perovskite film with PDAI helps in achieving efficient PSC with a PCE as high as 16.10%, a JSC of 21.45 mA cm-2, a VOC of 1.09 V, and FF of 70.21%, with negligible hysteresis and excellent moisture stability which shows unchanged PCE after 1440 h in a relative humidity of 15 ± 5%. Most strikingly, this ultra-thin 2D passivation layer by the use of PDA cations as a bulky spacer not only passivates the defects on the surface of perovskite film but also induces self-healing properties in PSCs which can be rapidly recovered after keeping away from water vapor exposure. This study introduces the cheap and extra stable perovskite solar cells with outstanding self-healing ability towards commercialization.

Sequentially to optimize the resource operation of material equipment, the workload calculation of virtual machines (VMs) is very important but demanding. The majority of accessible journalisms spotlight on each resource forecast or distribution independently, however mutually of them be extremely interconnected. In this paper, we suggest a Versatile Genesiological Algorithm (GA) to energetically predict the resource deployment and power utilization in cloud information hub.[1] We prepare a Versatile development dilemma of resource distribution, which believes the CPU and memory consumption of VMs and PMs, and the energy utilization of information hub. The suggested GA predicts the resource requisite of subsequently instance gap as per the past information in earlier instance gaps. We additionally suggest a VM position design to assign VMs for subsequent instance gap depend on the forecast outcomes of GA. In our replication-supported investigation, the best clarification for resource forecast over steady and unbalanced operation inclination is establish by the suggested GA. The forecast outcome be better to the earlier suggested Grey predicting form. Outcomes illustrate that the suggested VM assignment design not simply boosts the normal operation stage of CPU and memory but also reduces the energy utilization of cloud information hub.[4].

The peroxi-photoelectrocoagulation process was evaluated for the removal of chemical oxygen demand (COD) and color from healthcare wastewater. A 2-level full factorial design with center points was created to investigate the effect of the process parameters, i.e., initial COD, H2O2, pH, reaction time and current density. Furthermore, the total energy consumption and average current efficiency in the system were evaluated. Predictive models for % COD, % color removal and energy consumption were obtained. The initial COD and pH were found to be the most significant variables in the reduction of COD and color in peroxi-photoelectrocoagulation process. Hydrogen peroxide only has a significant effect on the treated wastewater when combined with other input variables in the process like pH, reaction time and current density. In the peroxi-photoelectrocoagulation process, current density appears not as a single effect but rather as an interaction effect with H2O2 in reducing COD and color. Lower energy expenditure was observed at higher initial COD, shorter reaction time and lower current density. The average current efficiency was found as low as 13% and as high as 777%. Overall, the study showed that hybrid electrochemical oxidation can be applied effectively and efficiently for the removal of pollutants from healthcare wastewater.

To investigate the dynamic responses of high-speed motor-gear transmission system in the electric vehicle, the non-linear coupled lateral-torsional-axial vibration model of motor-gear-rotor coupling system is developed based on the engagement of gears under various excitations. Firstly, the electromagnetic radial and tangential forces of the permanent magnetic synchronous machine are analyzed by finite element method, and the influences of the extracted electromagnetic radial and tangential force with considering the slot effect and magnetic saturation effect is presented. Furthermore, the dynamic characteristics of the motor-gear-rotor coupling system with the effects of the time-varying mesh stiffness, electromagnetic excitations and gear eccentricity are analyzed. The simulation results reveal the phenomenon that torsional vibration displacements are larger than those in lateral and axial directions, which is more obvious than the model without motor coupling. Meanwhile, the vibrations due to the time-varying mesh stiffness, gear eccentricity, slot effect and magnetic saturation effect are distinguished at different operation speed. Additionally, nonlinear motions are observed due to the electromagnetic excitations, including limit cycles and jumping phenomena for the motor rotor and gears. The research results lay a foundation for dynamic characteristics and fault diagnosis of the high-speed motor-gear transmission system for the electric vehicle.

The problem of purchasing power of population plays a dominant role in the economy of the republic as a factor affecting many important indicators of the country. That’s way, the authors investigated the cash incomes and expenditures of the population over the last 20 years and found that in conditions when the level of national income per capita is low, the mast important is to reduce the cost of power plants in order to make them widely sold among the population and increase the share of energy generated renewable sources in the overall balance of energy consumption.

Power electronics and other static controllers are making a major impact on future power systems through application in transmission, distribution, and small generation. Applications in transmission and distribution include HVDC, FACTS and Custom Power. “The Flexible AC Transmission Systems (FACTS) — a new technology based on power electronics — offers an opportunity to enhance controllability, stability, and power transfer capability of AC transmission systems.” In this project the control of power flow in a transmission system using a FACTS controller UPFC is understood. Second, the operation of UPFC using a control system which is based on d-q axis theory is also studied. Finally load flow results and modeling of a power system in MATLAB, and by installing UPFC in transmission link, its use as power flow  controller is seen.

The Sun is the main source of energy on our planet. For several billion years, biological systems have acquired the unique ability to efficiently convert energy from the sun through photosynthesis. The study of photosynthesis is a topical area of scientific research that will make it possible to solve the problem of obtaining environmentally friendly energy from water.

.In photosynthesis, the source of electrons is water, the oxidation of which produces electrons, protons and molecular oxygen. Oxidation of water takes place in photosystem II (PS-II). X-ray structural studies showed that the PS-II molecule consists of one or two subunits. The latter includes 108 electro-photoactive molecules, has 2 clusters with a spatial configuration in the form of a “chair”, the chemical composition is Mn4CaO5. The manganese and calcium atoms in the cluster, without interacting with each other, form chemical bonds only with oxygen. The Mn4CaO5 cluster contains 4 water molecules, two molecules each at Mn in position 4 and Ca, forming a complex in the form of Mn4O5Ca(H2O)4.

Analysis of the PS-II structure indicates that the components of the enzyme molecule form charge-transfer complexes (CTC) with each other and form a semiconductor structure that performs light-harvesting and electron transport functions. The cluster structure is optimized in accordance with the spatial characteristics of the water molecule.

Based on the data on the structure of PS-II, it is possible to describe with a high degree of reliability the mechanism of the process of generation of H+, O2↑, e- ions from water as a result of a photoenzymatic reaction. Light energy from light-harvesting molecules and their complexes migrates along the semiconductor structure of PS-II to the active center of the biocatalyst. This is accompanied by conformational changes in the Mn4O5Ca(Н2О)4 cluster, which results in the breaking of chemical bonds of water and the formation of atomic oxygen and 2 protons. Atomic oxygen in the aquatic environment forms hydrogen peroxide. The catalytic oxidation of hydrogen peroxide by the Mn4+ ion leads to the formation of oxygen, hydrogen ions, and heat is also released by the reaction Н2О2 – 2е- → О2↑ + 2Н+ + 23,5 kcal. In this case, Mn4+ is reduced to Mn2+, and then it is oxidized to Mn4+ upon transfer of the reducing equivalents of PS II. Two protons in water form hydronium ions according to the reaction Н+ + Н2О → Н3О+, which are electrochemically reduced to molecular hydrogen according to the scheme 2Н3О+ + 2e- → 2 Н2О + Н2↑. Thus, the PS-II cluster is a key structural entity that provides the splitting of water and the production of hydrogen and oxygen through the conversion of solar energy. In addition, it was found that the PS-II cluster in the form of a crystal does not lose the ability to split water under the action of light quantum. It should be added that a catalyst of similar qualitative composition Ca(MnO4)2 is used for the decomposition of hydrogen peroxide in space jet technology.

Biodiesel (BD) fuel belongs to an environmentally friendly, alternative energy source. It has a number of advantages over diesel fuel from petroleum: it is fireproof, has a higher flash point, and when burned, emissions of toxic substances are minimal.

It is most promising to obtain BD under supercritical (SC) conditions, above the critical point of methanol or ethanol. A mobile flow-through SC unit was created, which included tanks for the initial products, a flow-through reactor (FRT) with a heating element, a refrigerator, a separator, a high-pressure pump, a control unit, a pressure regulator, and a FTR made of a thick-walled stainless steel tube bent in the form of a spiral. A gas burner was used as a heating element, the operation of which was controlled by an automated HMI PLC SCADA system. The HMI PLC SCADA complex was used to enter usage environments, as well as to ensure the collection and data processing of the transesterification reaction. A significant advantage of the created mobile flow-through SC unit was its small size, high productivity, and environmental safety.

A study was carried out to optimize the operation parameters of a flow-through SC unit for a DB obtaining. When describing the processes occurring in FTR, a kinetic model was adopted, which included a number of assumptions. As a model, an isothermal plug-flow reactor (PFR) was considered, in which the volume of the reaction mixture does not change along the entire length of the FRT, and there was no reverse and radial transfer of substances. The movement of the flow of substances in the PFR proceeded only in the longitudinal direction, like a piston. In this case, the residence time of all components of the reaction mixture in the PFR was constant. The simplified kinetic model did not take into account the formation of intermediates. The order of the reaction with respect to the alcohol pressure was taken as 1, and the transesterification process was described by one irreversible first-order reaction.

As a result of calculations, the values of the effective rate constants of the transesterification reaction were obtained depending on the molar ratio of alcohol to oil. The reaction rate constant was determined by the least squares method by comparing experimental data on oil conversion with calculated data. The values of the effective reaction rate constants depending on temperatures in the range of 320-380 °C were used to determine the activation energy Ea of SC transesterification of oil at various ratios of the mixture – ethanol / oil, using the Arrhenius equation. It was found that the system must overcome the energy barrier, beyond which the reaction rate constant increases. The reaction rate constant increased 85-fold when the temperature was increased from 200 °C to 350 °C. Thus, high temperatures were necessary to overcome the energy barrier. It was found that the rates of the transesterification reaction under subcritical conditions are two orders of magnitude lower than under SC parameters.

Off-cut wood pieces are often dumped by sawmills as they are considered to be wastes in the wood industry. A certain portion of timber has to be removed also due to inadequate length of sawn timber material. Finger jointing technique is used to eliminate wood defects which weaken the strength of sawn wood plank and unused short pieces can even be used for obtaining defect free longer lengths of timber. A study was undertaken to evaluate the tensile strength performance and major failure modes of the finger-jointed productions. A finger profile of 13 mm finger length, 4 mm pitch and 1 mm tip width were used in the study. The sections were joined using PVAc adhesive. BS 373: 1957 and BS EN 15497:2014 were used as standards for tests. The test for tensile properties were performed using Universal Testing Machine (UTM 100 PC) with loading plate moving speed of 01mm/min. Load vs. displacement variation was obtained and maximum load was identified to calculate ultimate tensile strength for evaluating the major failure modes. Density and major finger joint failure modes were also investigated.

The major failure mode of the finger- jointed seven timber species subjected to a tensile test was mainly due to glue line failure (47.14%), followed by wood grain failure (24.28 %) and fiber failure(15.71%). The least failure mode was recorded as weak finger joint (12.85 %). The highest mean finger joint strength was obtained from Grandis (50.23 N/mm2) timber species and least mean finger joint strength was recorded in Kumbuk (16.88 N/mm2) timber species. There is no considerable relationship between Density and the failure occurrence of finger-jointed timber species. This results would be benefited for finger-jointed furniture manufacturing industry for sustainable use of wood waste.

The principal aim of this paper is to develop building bioclimatic charts for unconditioned buildings, especially for arid and hot climates in Algeria. These charts are based on temperature and relative humidity for a given location according to the ASHRAE-55 comfort zone. In this study, two types of bioclimatic charts have been designed to identify the comfort zone achievable in Ouargla city and delimitate the climatic conditions under which various design strategies for summer comfort can be applied.

The charts applied to Ouargla city determined a hot and dry period from June to September, which needs a high thermal mass with night ventilation to reach the comfort zone.

The results of this study contribute to perceive the thermal behavior of building design and provide guidelines to develop a specific concept of what the typical building composition should look like in arid and hot climates.

Effective removal of textile dyes is important in environmental remediation especially for decontamination of wastewater. Herein, we report the synthesis of mesoporous silica nanoparticles (MSNs) from paddy husk with varying concentrations of surfactants, Cetyltrimethylammonium bromide (CTAB), and Polyethyleneglycol (PEG) by sol-gel synthesis method. Ratios of the surfactants CTAB: PEG were varied as 2:0 (MSN1),1:1 (MSN2), 0:2 (MSN3). MSNs were characterized by scanning electron microscope (SEM), Brunauer-Emmett-Teller surface area analyzer (BET), Thermogravimetric analyzer (TGA), and X-ray diffractometer. According to the SEM images, MSNs of all the combinations were aggregated with spherical and irregular shaped nanoparticles. MSNs synthesized with a 1:1 surfactant ratio showed more spherical nanoparticles. BET surface areas of MSN1, MSN2, and MSN3 are 468.35, 95.94, 177.46 m2/g, respectively. TGA curve indicated that desorption of the physisorbed water was completed at 125 °C. The effect of dye removal by the MSNs was studied on the adsorption of methylene blue (MB). Effect of dye concentration (5-30 mg/l), adsorbent dosage (5-20 mg), pH of the medium (2-10), ionic strength of the medium (0-6g/l NaCl), presence of a heavy metal (Pb2+- 0-500 mg/l) and temperature (25-55 °C) on MB adsorption was studied. At all the varied parameters, the adsorption efficiency of MB varied as MSN1> MSN3> MSN2, being similar to the trend of the surface area. The percentage of MB adsorption decreased with increasing MB concentration while it increased with increasing adsorbent dosage. The highest efficiency of MB adsorption was obtained at pH 10 and it decreased with increasing ionic strength and increasing concentration of heavy metal ions. The maximum percentage of MB adsorption resulted at 55 °C. Therefore, it can be concluded that the MSNs synthesized using only CTAB as the surfactant is an effective adsorbent in removing textile dyes from wastewater.

Fibers has been used in concrete by different researches since a few decades. Natural fibers are widely use as additive material in concrete to enhance the strength and mechanical properties of concrete. It has been observed that by using fiber reinforced composites (FRC) the weight and manufacturing cost can be reduced. The purpose of this study is to find out the flaws in reinforced concrete (RC) columns regarding compressive toughness and their remedial measures. This paper includes the state of the art review of behavior of RC columns under compressive load, role of toughness and available measure to increase compressive toughness (CT). Analysis of chemical, mechanical and physical properties of banana fiber is done for choosing it as suitable fiber. Usage of banana fiber in different proportions in concrete and its effect towards enhancing the compressive toughness is also studied. The compressive strength of concrete by using FRC is reduced in most of the cases but ability to absorb energy is increased. There are a very less number of experimental studies present in literature regarding use of banana fiber in FRC so there is need of a lot of work on it. Banana fiber can be used in future studies to enhance plasticity of concrete and its fire resistance.

Solar photovoltaic (PV) panels experience long-term performance degradation as compared to their initial performance, resulting in lower like-per-like efficiencies and performance ratios. Manufacturers of solar photovoltaic modules normally guarantee a lifespan of more than 20 years. To meet such commitments, it is important to monitor and mitigate PV module degradation during this period, as well as beyond, to recognise maintenance and repair needs. Solar PV modules degrade over time, becoming less effective, less reliable, and eventually unusable. The effects of transient and performance loss rates on the output performance of polycrystalline silicon (p-Si) solar PV modules are the focus of this study. PV modules’ electrical performance and solar energy conversion efficiency change as solar irradiance and ambient temperature change. A rise in ambient temperature or a decrease in solar irradiance, for example, all result in a reduction in performance.

Large variations in operating conditions due to uncontrollable external parameters such as cloud movement and wind velocity, as well as changes in factors external to PV systems such as unexpected shading, inverter problems, and control failures, may trigger transient performance changes on PV modules output. The data used in this analysis were from the Warrenpoint site location of the Electric Supply Board (ESB) for the years 2016-2020. Clear days in winter, spring, summer, and autumn were caused by a rise in daily sunshine hours in February, May, June, and September, according to the output performance. Due to the highest amount of solar irradiation at the site location, these days saw an increase in PV output generation. According to the performance loss rates, the median degradation rates in 2016 (4.5%/year to 14%/year) and 2017 (0.1%/year to 5.2%/year) are 8.40%/year and 3.87%/year, respectively. This means that the degradation rate is greater than 1%/year, the hazardous probability is between 90% and 100%, and severity of 10 is given (With an associated failure of corrosion in solder bonds). 2018 (-7.5%/year to 2.5%/year), 2019 (-16%/year to -23%/year), and 2020 (-5.1%/year to -10% /year) had median degradation rates of -2.75%/year, -18.23%/year, and -5.2%/year, respectively. This shows that the degradation rates are less than 1% per year, and their hazardous probabilities range from severity rank 9 to 1, or 80% to 70% to 0% safety risk. All of these factors have a negative impact on PV output performance.