Synthesis and Characterization of Copper Indium Sulfide Microsphere and its Application in Low-Cost Solar Cell

CuInS2 microsphere was synthesized by Ultrasonic method in propylene glycol, as solvent, and copper complex, indium chloride and thioacetamde (TAA) as precursors. Optimum conditions such as reaction time, solvent type, sulfur source, and ultrasonic power were determined. Then thin film of CuInS2 was prepared and its application in solar cells was investigated. To investigate solar cell application of CuInS2 in the present experiment, at first CuInS2 paste was prepared from nanoparticle and then thin film prepared by doctor balding. I–V curves offer key parameters including short-circuit current (ISC) and the opencircuit voltage (VOC). Another important parameter for solar cells is fill factor (FF). A series of analysis including X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (PL) spectroscopy were performed to characterize the CusInS2 microsphere. The optical band gap of CuInS2 microsphere was estimated to be 2.28 eV. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3499

Venturi nozzles for desalination brine discharges

Seawater desalination is a reliable way to confront the growing challenges of freshwater demands in the world. Brine is the primary by-product of this process and needs to be carefully managed and discharged back into the sea. In coastal desalination plants, the use of submerged outfall as a pipeline laying on the ocean floor is a popular strategy to minimize the environmental impacts of brine discharge. The Venturi nozzle has been proposed as a more efficient method for dispersing brine into the ocean. However, it requires a high exit velocity, which poses limitations for steep nozzle angles in shallow waters. This study aims to investigate the benefits of a lower range of exit velocities in the Venturi nozzles. The 60◦ inclined dense jet from a Venturi nozzle was explored, numerically and experimentally, and the results were compared to those of a simple dense jet. Comparisons showed that the Venturi nozzle decreases the flow path and diminishes flow dilution at the critical points. However, this reduction can be compensated by increasing the discharge Froude number to reach the same trajectory as a simple jet. It is important to note that this compensation is intricately linked to the discharge velocity, and it makes the use of Venturi nozzles for brine discharge a challenging proposition in both deep and shallow waters

Simulation of Solid Oxide Fuel Cell Anode in Aspen HYSYS—A Study on the Effect of Reforming Activity on Distributed Performance Profiles, Carbon Formation, and Anode Oxidation Risk

A distributed variable model for solid oxide fuel cell (SOFC), with internal fuel reforming on the anode, has been developed in Aspen HYSYS. The proposed model accounts for the complex and interactive mechanisms involved in the SOFC operation through a mathematically viable and numerically fast modeling framework. The internal fuel reforming reaction calculations have been carried out in a plug flow reactor (PFR) module integrated with a spreadsheet module to interactively calculate the electrochemical process details. By interlinking the two modules within Aspen HYSYS flowsheeting environment, the highly nonlinear SOFC distributed profiles have been readily captured using empirical correlations and without the necessity of using an external coding platform, such as MATLAB or FORTRAN. Distributed variables including temperature, current density, and concentration profiles along the cell length, have been discussed for various reforming activity rates. Moreover, parametric estimation of anode oxidation risk and carbon formation potential against fuel reformation intensity have been demonstrated that contributes to the SOFC lifetime evaluation. Incrementally progressive catalyst activity has been proposed as a technically viable approach for attaining smooth profiles within the SOFC anode. The proposed modeling platform paves the way for SOFC system flowsheeting and optimization, particularly where the study of systems with stack distributed variables is of interest

System Level Exergy Assessment of Strategies Deployed for Solid Oxide Fuel Cell Stack Temperature Regulation and Thermal Gradient Reduction

Several operational strategies for solid oxide fuel cell (SOFC) temperature regulation and temperature gradient minimization at cell scale have previously been assessed by the authors (Amiri et al., Ind. Eng. Chem. Res., 2016). The application of such strategies at system scale, however, requires a numerical linkage between the cell and the system performance metrics allowing simultaneous evaluation of the dominant process interactions. The objective of this study is to analytically examine the effectiveness and applicability of the mentioned thermal management methods at system scale. To achieve this, a system level exergy analysis is presented by using a modeling platform in which a detailed four-cell short stack module and the balance-of-plant (BoP) are integrated. Linkage between the system performance metrics and the stack internal temperature gradient is specifically emphasized. For this, the exergy intensive points (unit operations) are identified throughout the plant. Subsequently, the effective strategies that had been employed for the cell level thermal management proposed in our previous work (Amiri et al., Ind. Eng. Chem. Res., 2016) are examined at the system level capturing the effects on the state of BoP exergy intensive components. Moreover, fuel design is proposed and evaluated as a potential thermal management strategy. Combination of a variety of measures including the exergy destruction rates, the electrical and thermal efficiencies, and the stack internal temperature gradient provides a comprehensive set of data contributing to the SOFC system thermal management

A Comparison of Dysphonia Severity Index in Female Teachers With and Without Voice Complaints in Elementary Schools of Tehran, Iran

Background: Teachers are the greatest group of professional voice users. Prolonged, continuous speaking in a loud voice at school may entail a bad vocal health. It seems that their occupational circumstances make them more likely to develop voice disorders in comparison with other groups. Objectives: The purposes of this study are 1) to compare teachers with and without voice complaint on the Dysphonia Severity Index and 2) to compare component measures that establish Dysphonia Severity Index. Materials and Methods: This study included 40 female teachers with voice complaint and 40 female teachers without voice complaint between the ages of 30 and 50 years who were teaching in elementary schools of Tehran city. Simple non-random sampling was done for selected teachers in two groups. The examinees were asked to produce the vowel /a/ three times for calculating any variables, then measures of maximum phonation time, jitter, highest phonational frequency, and lowest intensity were obtained for each subject with Praat and Phonetogram softwares and incorporated into multivariate Dysphonia Severity Index formula. Kolmogoro- Smirnov one sample test and independent sample T-Test was used, the significance level was set at P < 0.05. Results: Results indicate that female teachers without voice complaint have significantly higher Dysphonia Severity Index scores than female teachers with voice complaint (mean Dysphonia Severity Index: 3.58 vs. 1.05, respectively), also significant differences are observed between groups of with and without complaint for four of components of the DSI (F0 high, I low, jitter and maximum phonation time) (P value = 0.001). Conclusions: The findings of this study indicate that there is a significant difference in Vocal Quality between teachers with and without voice complaint. This finding may indicate teachers with voice complaint have worse vocal quality that means they are at risk for voice problems. This information may be very important for voice professionals and, speech and language pathology to advice teachers with voice complaint and manage to advocate "good vocal health”

Planar solid oxide fuel cell modeling and optimization targeting the stack's temperature gradient minimization

Minimization of undesirable temperature gradients in all dimensions of a planar solid oxide fuel cell (SOFC) is central to the thermal management and commercialization of this electrochemical reactor. This article explores the effective operating variables on the temperature gradient in a multilayer SOFC stack and presents a trade-off optimization. Three promising approaches are numerically tested via a model-based sensitivity analysis. The numerically efficient thermo-chemical model that had already been developed by the authors for the cell scale investigations (Tang et al. Chem. Eng. J. 2016, 290, 252-262) is integrated and extended in this work to allow further thermal studies at commercial scales. Initially, the most common approach for the minimization of stack's thermal inhomogeneity, i.e., usage of the excess air, is critically assessed. Subsequently, the adjustment of inlet gas temperatures is introduced as a complementary methodology to reduce the efficiency loss due to application of excess air. As another practical approach, regulation of the oxygen fraction in the cathode coolant stream is examined from both technical and economic viewpoints. Finally, a multiobjective optimization calculation is conducted to find an operating condition in which stack's efficiency and temperature gradient are maximum and minimum, respectively

Modification of classical electron transport due to collisions between electrons and fast ions

A Fokker-Planck model for the interaction of fast ions with the thermal electrons in a quasi-neutral plasma is developed. When the fast ion population has a net flux (i.e. the distribution of the fast ions is anisotropic in velocity space) the electron distribution function is significantly perturbed from Maxwellian by collisions with the fast ions, even if the fast ion density is orders of magnitude smaller than the electron density. The Fokker-Planck model is used to derive classical electron transport equations (a generalized Ohm's law and a heat flow equation) that include the effects of the electron-fast ion collisions. It is found that these collisions result in a current term in the transport equations which can be significant even when total current is zero. The new transport equations are analyzed in the context of a number of scenarios including $\alpha$ particle heating in ICF and MIF plasmas and ion beam heating of dense plasmas

Evaluation of Fuel Diversity in Solid Oxide Fuel Cell System

Operability of Solid Oxide Fuel Cell (SOFC) on numerous fuels has been widely counted as a leading advantage in literature. In a designed system, however, switching from a fuel to another is not practically a straightforward task as this causes several system performance issues in both dynamic and steady-state modes. In order to demonstrate the system fuel diversity capabilities, these consequences must be well-evaluated by quantifying the characteristic measures for numerous fuel cases and also potential combinations. From this viewpoint, the numerical predictive models play a critical role. This paper aims to investigate the performance of a SOFC system fed by various fuels using a demonstrated system level model. Process configuration and streams results of a real-life SOFC system rig published in literature are used to validate the model. The presented model is capable not only of capturing the system performance measures but also the SOFC internal variable distributions, allowing the multiscale study of fuel switching scenarios. The fuel change impacts on the system are simulated by considering various fuel sources, i.e., natural gas, biogas, and syngas. Moreover, applications of simulated fuel mixtures are assessed. The modelling results show significant concerns about fuel switching in a system in terms of variation of efficiencies, stack internal temperature and current density homogeneity, and environmental issues. Moreover, the results reveal opportunities for multi-fuel design to address the operation and application requirements such as optimisation of the anode off-gas recycling rate and the thermal-to-electrical ratio as well as the system specific greenhouse gases, i.e., g-COx/Wh release

Tensile rotary power transmission model development for airborne wind energy systems

Rotary airborne wind energy (AWE) systems are a family of AWE devices that utilise networked kites to form rotors. One such device is the Daisy Kite developed by Windswept and Interesting. The Daisy Kite uses a novel tensile rotary power transmission (TRPT) to transfer power generated at the flying rotor down to the ground. Two dynamic models have been developed and compared; one with simple spring-disc representation, and one with multi-spring representation that can take account of more degrees of freedom. Simulation results show that the angular velocity responses of the two TRPT models are more closely correlated in higher wind speeds when the system shows stiffer torsional behaviour. Another interesting point is the observation of two equilibrium states, when the spring-disc TRPT model is coupled with NREL's AeroDyn. Given the computational efficiency of the simpler model and the high correlation of the results between the two models, the simple model can be used for more demanding simulations

On a linear combination of some expressions in the theory of the univalent functions

Let H (α) denote the class of regular functions f(z) normalized so that f (0)=0 and f′ (0)=1 and satisfying in the unit disc E the condition 0$$]]> for fixed α. It is known that H (0) is a particular class NW of close-to-convex univalent functions. The authors show the following results: Theorem 1. Let f(z) ∈ H (α). Then f(z) ∈NW if α≤0 and z ∈ E . Theorem 2 . Let f(z) ∈NW. Then f(z) ∈ H (α) in | z |= r < r α where i) , α≥0 and ii) , α<0. All results are sharp. Theorem 3 . If f(z)=z+a 2 z 2 + a 3 z 3 +... is in H (α) and if μ is an arbitrary complex number, then .Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41631/1/605_2005_Article_BF01472573.pd