SCAPS 1D Simulation of a Lead-Free Perovskite Photovoltaic Solar Cell Using Hematite as Electron Transport Layer

In recent years, there has been remarkable progress in the performance of metal halide perovskite solar cells. Studies have shown significant interest in lead-free perovskite solar cells (PSCs) due to concerns about the toxicity of lead in lead halide perovskites. CH3NH3SnI3 emerges as a viable alternative to CH3NH3PbX3. In this work, we studied the effect of various parameters on the performance of lead-free perovskite solar cells using simulation with the SCAPS 1D software. The cell structure consists of α-Fe2O3/CH3NH3SnI3/PEDOT: PSS. We analyzed parameters such as thickness, doping, and layer concentration. The study revealed that, without considering other optimized parameters, the efficiency of the cell increased from 22% to 35% when the perovskite thickness varied from 100 to 1000 nm. After optimization, solar cell efficiency reaches up to 42%. The optimization parameters are such that, for example, for perovskite: the layer thickness is 700 nm, the doping concentration is 1020 and the defect density is 1013 cm−3, and for hematite: the thickness is 5 nm, the doping concentration is 1022 and the defect concentration is 1011 cm−3. These results are encouraging because they highlight the good agreement between perovskite and hematite when used as the active and electron transport layers, respectively. Now, it is still necessary to produce real, viable photovoltaic solar cells with the proposed material layer parameters.

LUT-based non-linearity compensation for BES III TOF’s time measurement

The impact of the integral non-linearity (INL) to the time resolution of HPTDC (High Performance Time to Digital Converter) is presented in this paper.An INL correction method based on look-up table (LUT),is proposed to minimize such INL and improve the time resolution.This scheme is implemented in a single Field Programmable Gate Array (FPGA) device for real-time compensation.The INL characteristic estimation is based on a statistical approach,in which a sufficiently large number of random input signals are measured.The prototype tests show that the deviation for time resolution due to INL can be reduced greatly,from more than 80 ps to less than 20 ps,which can meet the requirement of BES (Beijing Spectrometer) III Time-Of-Flight detector.

Impact of a background velocity field on solidification growth of single-crystal nuclei using the PF-LBM

To promote/inhibit ice formation in the natural environment and industrial systems,the growth and evolution process of ice single-crystal nuclei were simulated using the phase field-lattice Boltzmann method(PF-LBM),and the influence of a background flow field on the growth of single-crystal nucleus dendrites was also analyzed.The results show that the flow field makes dendrite growth asymmetric.The growth of dendrites is more developed on the upstream side than on the downstream side.The dendrite tip growth rate and tip radius are greater on the upstream side than on the downstream side.The solid phase ratio is greater with a background flow field than without one.The higher the flow velocity is,the more developed the dendrites on the upstream side,the faster the dendrites grow,and the higher the dendrite tip growth rate.The dendrites on the backflow side have a lower flow rate and a lower degree of supercooling than those on the upstream side,which inhibits the solidification process,the growth rate is slow,and the dendrites are underdeveloped.

Enhanced Vibrating Particles System Algorithm for Parameters Estimation of Photovoltaic System

To evaluate the performance of a photovoltaic panel, several parameters must be extracted from the photovoltaic. These parameters are very important for the evaluation, monitoring and optimization of photovoltaic. Among the methods developed to extract photovoltaic parameters from current-voltage (I-V) characteristic curve, metaheuristic algorithms are the most used nowadays. A new metaheuristic algorithm namely enhanced vibrating particles system algorithm is presented here to extract the best values of parameters of a photovoltaic cell. Five recent algorithms (grey wolf optimization (GWO), moth-flame optimization algorithm (MFOA), multi-verse optimizer (MVO), whale optimization algorithm (WAO), salp swarm-inspired algorithm (SSA)) are also implemented on the same computer. Enhanced vibrating particles system is inspired by the free vibration of the single degree of freedom systems with viscous damping. To extract the photovoltaic parameters using enhanced vibrating particles system algorithm, the problem can be set as an optimization problem with the objective to minimize the difference between measured and estimated current. Four case studies have been implemented here. The results and comparison with other methods exhibit high accuracy and validity of the proposed enhanced vibrating particles system algorithm to extract parameters of a photovoltaic cell and module.

Compressive and Sealing Characteristics of PTFE under Cyclic Loading-unloading

Compressive and sealing characteristics of PTFE under cyclic loading-unloading at room temperature are studied in order to evaluate the cyclic sealing performance of control valve comprehensively. The unloading characteristics are different from the loading ones, therefore there is hysteresis between the unloading and loading curves. Compressive hysteresis is the main factor that causes sealing hysteresis. The leakage rate of PTFE complies with the power law before it enters the relatively stable region. Lastly, the effect of working pressure on the compressive and sealing characteristics is discussed. The experimental results show that the working pressure has little effect on compressive deformation but has a great influence on leakage rate.

Elaboration of Explanatory Factors of Accidents in Cameroon by Factorial Correspondence Analysis

The aim of this paper is to examine the causes of road accidents in Cameroon. The Douala-Yaoundé highway was chosen as the case of study. Available field data recorded from the year 2006 to 2011, have enabled the analysis of each accident. The method used here is the factorial correspondence analysis;which aims to bring in a small number of dimensions, most of the initial information, focusing not on the absolute values, but the correspondence between the variables, that is to say the relative values. From this analysis, it appears that, of the 906 accidents recorded during this period, top five causes account for nearly 83% of the information provided by the set of variables on the occurrence of road accidents. These causes are: driver inattention, lack of control, over speeding, improper overtaking and tire puncture. These results require involvement in the construction of road safety policies through training, sensitization and adequate repressions as well as administrative reforms and research policy in road safety.

Hydropower Production Optimization from Inflow: Case Study of Songloulou Hydroplant

The model of nonlinear power generation function is developed to generate optimal operational policies for Songloulou inflow in Cameroon and test these policies in real time conditions. Our model is used to adjust operational regimes for the Songloulou reservoir under varying flows (turbined and deversed) using a dynamic program. A more interesting approach, proposed in this article, consists of combining both the principle of decomposition by resources (or quantities) and the technique of dynamic programming. Dynamic programming is an appropriating optimization algorithm that is used for complex non-linear inflow operational policies and strategies. In this case study, our optimization model is used and confirmed maximizing large scale of hydropower in a period of time step by the integration of several. The high non linearity of our study object is the first stage of difficulty which brought us to combined least squared and Time Varying Acceleration Coefficients Particle Swarm (TVACPSO) to obtain appropriate production function which generated optimal operational policies for the Songloulou hydropower in sub-Saharan region and after we tested it in the company policies operational at real time conditions. The model could be successfully applied to other hydropower dams in the region.

Thermodynamic Analysis of the Performance of a Single-Effect Absorption Refrigeration System Using the Ammonia/Sodium Thiocyanate Couple

This paper aims at presenting analysis of the thermodynamic of the performance of an absorption refrigeration system of the single-effect ammonia/sodium thiocyanate couple. Since the generator is the starting point for the operation of system, one of the most important point to be addressed in this work is to determine the generator’s temperatures at which the system can accept the best quantities and qualities of energy. A mathematical model has been developed to study the performance of the system. Equations obtained from the thermodynamic properties of the ammonia/sodium thiocyanate couple were implemented in Matlab. The analysis consists of determining the effects of the generator’s temperature on the energy performance of the system. The computerized performance parameters are the coefficient of performance and the energy efficiency. Results indicate that the coefficient of performance increases with the temperature of the generator. Moreover, these remarks are not observed on the exergetic efficiency, because the latter increases until its maximum value 0.43, in order to decrease until its final value 0.35. In addition, the maximum value of the coefficient of performance tends towards 0.7 with increasing generator temperature. The system admits better operation when the generator temperatures are between 80°C and 90°C. The determination of this temperature interval by simulation can be use as a variable setting point in controlling the real system.

Comparative analysis of chemical profiles of Radix Astragali between ultrafine granular powder and sliced traditional material

Radix Astragali,one of the most popular herbs in traditional Chinese medicine(TCM),is used to strengthen the immune system,protect liver function,fight bacteria and viruses,and treat diabetes,heart failure and seasonal allergies.In recent years,a new form of Radix Astragali material processed by cell wall disrupting technology,namely ultrafine granular powder(UGP)has been introduced into the market.In order to determine chemical consistency and homogeneity of the UGP material prepared from sliced traditional materials(TM)of Radix Astragali,multiple batches of the UGP and TM samples derived from Astragalus membranaceus var.mongholicus were analyzed by UHPLC/DAD-MS using isoflavones and triterpenoid glycosides as marker compounds.The results demonstrated that the chemical profiles of UGP was identical or similar to that of TM,but UGP was highly homogeneous in terms of marker compound contents as assessed,e.g.,by the relative standard deviation values of the nine marker compounds in the range of 8.55%−43.80%for TM2 compared against 1.70%−8.38%for UGP2.Macromolecular component preparation and 1H NMR analyses indicated that TM4 and its corresponding UGP4 produced similar polysaccharides,but the later had approximately two-fold dissolution rate of the polysaccharides when compared to the former(yield 7.22±0.35%vs 3.39±0.20%).This study confirms that UGP of Radix Astragali is chemically consistent and homogenous,supporting its use as a promising material in TCM prescriptions.

A high precision time-to-digital converter based on multi-phase clock implemented within Field-Programmable-Gate-Array

In this paper, the design of a coarse-fine interpolation Time-to-Digital Converter (TDC) is implemented in an ALTERA’s Cyclone FPGA. The carry-select chain performs as the tapped delay line. The Logic Array Block (LAB) having a propagation delay of 165 ps in the chain is synthesized as delay cell. Coarse counters triggered by the global clock count the more significant bits of the time data. This clock is also fed through the delay line, and LABs create the copies. The replicas are latched by the tested event signal, and the less significant bits are encoded from the latched binary bits. Single-shot resolution of the TDC can be 60 ps. The worst Differential Nonlinearity (DNL) is about 0.2 Least Significant Bit (LSB, 165 ps in this TDC module), and the Integral Nonlinearity (INL) is 0.6 LSB. In comparison with other architectures using the synchronous global clock to sample the taps, this architecture consumed less electric power and logic cells, and is more stable.

Energy harvester array using piezoelectric circular diaphragm for rail vibration

Generating electric energy from mechanical vibration using a piezoelectric circular membrane array is presented in this paper.The electrical characteristics of the functional array consisted of three plates with varies tip masses are examined under dynamic conditions.With an optimal load resistor of 11 k,an output power of 21.4 m W was generated from the array in parallel connection at 150 Hz under a pre-stress of 0.8 N and a vibration acceleration of9.8 m/s2.Moreover,the broadband energy harvesting using this array still can be realized with different tip masses.Three obvious output power peaks can be obtained in a frequency spectra of 110 Hz to 260 Hz.The results show that using a piezoelectric circular diaphragm array can increase significantly the output of energy compared with the use of a single plate.And by optimizing combination of tip masses with piezoelectric elements in array,the frequency range can be tuned to meet the broadband vibration.This array may possibly be exploited to design the energy harvesting for practical applications such as future high speed rail.

Thermodynamic optimization for a quantum thermoacoustic refrigeration micro-cycle

A model of quantum thermoacoustic refrigeration micro-cycle(QTARMC)is established in which heat leakage is considered.A single particle contained in a one-dimensional harmonic potential well is studied,and the system consists of countless replicas.Each particle is confined in its own potential well,whose occupation probabilities can be expressed by the thermal equilibrium Gibbs distributions.Based on the Schrodinger equation,the expressions of coefficient of performance(COP)and cooling rate for the refrigerator are obtained.Effects of heat leakage on the optimal performance are discussed.The optimal performance region of the refrigeration cycle is obtained by the using ofΩobjective function.The results obtained can enrich the thermoacoustic theory and expand the application of quantum thermodynamics.

Cryogenic System for PKU-FEL

PKU-FEL based on superconducting (SC) accelerator facility is under construction at PekingUniversity. It will run in IR (5 - 10 μm) and THz (100 - 3000 μm) region as an ideal experimental FEL platform for universities. The SC accelerator facility is composed of a DC-SC injector and a 1.3-GHz 2 × 9-cell SC accelerator. In order to better the performance, the injector and the accelerator are bath-cooled by 2 K super fluid helium in cryostats. A 2 K cryogenic system has been designed, constructed and assembled.

Effects of lead pollution on soil microbial community diversity and biomass and on invertase activity

Lead(Pb)pollution is one of the most widespread and harmful environmental problems worldwide.Determination of changes in soil properties and microbial functional diversity due to land use is needed to establish a basis for remediation of soil pollution.This study aimed to investigate soils contaminated by Pb from different sources and to analyze the functional diversity and metabolism of soil microbial communities using Biolog technology.Pb pollution(>300 mg kg-1)significantly influenced the diversity and metabolic functions of soil microbial communities.Specifically,Pb contamination significantly reduced soil microbial biomass carbon(C)and nitrogen(N)levels and catalase activity while increasing invertase activity.Furthermore,Biolog EcoPlate assays revealed that Pb pollution reduced the general activities of soil microorganisms,suppressing their ability to utilize C sources.In Pb-contaminated areas lacking vegetation cover,Shannon,Simpson,and McIntosh diversity indices of soil microorganisms were significantly reduced.The microbial diversity and biomass C and N levels were affected by land use and soil properties,respectively,whereas soil enzyme activity was primarily affected by the interaction between land use and soil properties.Our results provide a reference and a theoretical basis for developing soil quality evaluation and remediation strategies.

Experimental Investigation on the Temperature Distribution Characteristics of the Evaporation Section in a Pulsating Heat Pipe

With the increasing demand for heat dissipation in the electronics industry, pulsating heat pipe(PHP) has attracted wide attention due to its simple structure and excellent heat transfer ability. However, due to the unique operational mechanism of PHP, the temperature distribution in the evaporation section is obviously not even during the operational process of PHP. When the PHP is used as a heat dissipater, the evaporation section of the PHP directly contacts with the chips and has great influence on the performance of the chips, so it is very important to investigate the temperature distribution characteristics in the evaporation section. In this paper, both the effects of the filling ratio and heat flux on these characteristics were investigated. The experimental results indicated that the temperatures of the middle "U" turn were the highest. When the heat flux and the filling ratio were 364 W/cm^2 and 36.3%, respectively, the maximum temperature difference between the middle "U" turn and the other "U" turns could be as high as 18.92 K. Furthermore, the temperature differences between the middle "U" turn and the other "U" turns firstly increased and then decreased with the increase of heat flux and filling ratio.

Effects of different biochars on antibiotic resistance genes during swine manure thermophilic composting

Elimination of antibiotic resistance genes(ARGs)in animal manure from concentrated animal feeding operations by thermophilic composting has drawn increasing attention.This study investigated the effects of sawdust biochar,corn stover biochar and peanut hull biochar with three spiked levels on ARGs in swine manure during thermophilic composting.Thirteen ARGs corresponding to four classes of antibiotics(tetracyclines,sulfonamides,macrolides and quinolones)were determined in the composting piles.Results indicated that the ten tested composting groups became fully mature after 30-day thermophilic composting process.tetM,tetO and ermB were reduced in all tested groups;tetC and tetG,tetX,sul1,sul2,ermF,qnrD and aac(6’)-Ib were mostly reduced under low level biochar addition but increased under higher level biochar addition;gyrA increased under medium biochar addition and reduced in other groups;oqxB remained comparatively stable throughout the composting process.The addition levels of spiked biochar are more important than types of spiked biochar on the removal of ARGs in the composting pile.The average removal rates of ARGs in the control group,low,medium and high level biochar addition groups were 0.24 logs,0.52-0.72 logs,-0.52-0.18 logs and-0.19-0.21 logs,respectively.In summary,low level biochar addition could enhance the elimination of studied ARGs in swine manure during the composting process,while medium level biochar addition to the composting piles would increase the risk of ARGs’propagation.

A novel cryogenic insulation system of hollow glass microspheres and self-evaporation vapor-cooled shield for liquid hydrogen storage

Liquid hydrogen(LH2)attracts widespread attention because of its highest energy storage density.However,evaporation loss is a serious problem in LH2 storage due to the low boiling point(20 K).Efficient insulation technology is an important issue in the study of LH2 storage.Hollow glass microspheres(HGMs)is a potential promising thermal insulation material because of its low apparent thermal conductivity,fast installation(Compared with multi-layer insulation,it can be injected in a short time.),and easy maintenance.A novel cryogenic insulation system consisting of HGMs and a selfevaporating vapor-cooled shield(VCS)is proposed for storage of LH2.A thermodynamic model has been established to analyze the coupled heat transfer characteristics of HGMs and VCS in the composite insulation system.The results show that the combination of HGMs and VCS can effectively reduce heat flux into the LH2 tank.With the increase of VCS number from 1 to 3,the minimum heat flux through HGMs decreases by 57.36%,65.29%,and 68.21%,respectively.Another significant advantage of HGMs is that their thermal insulation properties are not sensitive to ambient vacuum change.When ambient vacuum rises from 10^-3 Pa to 1 Pa,the heat flux into the LH2 tank increases by approximately 20%.When the vacuum rises from 10^-3 Pa to 100 Pa,the combination of VCS and HGMs reduces the heat flux into the tank by 58.08%-69.84% compared with pure HGMs.

Metagenome analysis reveals potential microbial functions in topsoil of wheat-maize rotation system with five-year application of fertilizers

Fertilization mode affects soil quality and ecological health.The effects of four fertilization regimens on lignocellulose content,readily degradable carbohydrate decomposition,and potential microbial functions in the topsoil of a wheat-maize rotation system between 2012 and 2017 were investigated.The fertilization regimens of control(control NFNB),high chemical fertilizer(HCF),high biochar plus low chemical fertilizer(HBLCF),and biochar-based fertilizer(BBF)were compared on soil fundamental properties,microbial structure,and potential function in soil carbohydrate degradation based on metagenome analysis.The diversity of carbohydrate-active enzyme genes in the topsoil microbial consortia in the four trials was primarily distributed within the ten ecologically most dominant phyla.Application of BBF was associated with the lowest decline in total nitrogen and P2O5(2012-2017:6.5%and 28.1%,respectively)and the most effective carbohydrate decomposition(2015-2017:67.0%for cellulose and 59.9%for readily degradable carbohydrate).Carbohydrate transport and metabolism accounted for 6.0%of reads assigned functional classification under the BBF regimen.These findings reveal the ecologically functional diversity of topsoil microorganisms and suggest BBF application as a promising strategy for sustainable agriculture and beneficial to soil health.

Investigation and analysis of the linkage mechanism and whole process cost of livestock manure organic fertilizer

In recent years,the utilization of manure resources for livestock and poultry farming has attracted a widespread attention,and manure resources utilization models suitable for different regional characteristics have formed gradually.Among them,the production of organic fertilizer from animal manure is a vital utilization method.However,there are still some problems such as high production costs,difficult sales,and the unwillingness of farmers to use organic fertilizers which have affected the breeding cycle and the sustainability of manure treatment in livestock and poultry breeding.This article selected 371 organic fertilizer plants,related farms and farmers in China,focusing on the main links of the entire process of livestock manure-organic fertilizer-farm application,and studied the mode of animal manure collection by organic fertilizer plants.The costs of organic fertilizer production and farmland application were discussed.Moreover,suggestions were made for the promotion and implementation of large-scale organic fertilizers to make good utilization of manure resources in livestock and poultry farming.

Seat tightness of pneumatic cryogenic control valve

Pneumatic cryogenic control valves(PCCV)are designed to meet the special requirements for the large cryogenic helium refrigeration system.Polychlorotrifluoroethylene(PCTFE)is adopted as the flat seal material of the valve seat.The leakage rates and compressive strain of the PCTFE gasket with different sealing stress are tested at both room temperature(293 K)and liquid nitrogen temperature(77 K).After 300 open/close cycles,the experimental results show that the sealing properties of the PCTFE gasket are improved.The leakage rates are about 10-8(293 K)and 10-4(77 K)Pam3 s-1 respectively.Finally,the effects of working pressure on sealing characteristics are discussed.The working pressure has little effect on compressive strain but it has a great influence on leakage rate.The leakage rate is linear with the working pressure of inlet at room temperature,but at liquid nitrogen temperature the leakage rate is linear with the square of the working pressure.