Temperature effects on the electrical performance of large area multicrystalline silicon solar cells using the current shunt measuring technique

The temperature effects on the electrical performance of a large area multicrystalline silicon solar cell with back-contact technology have been studied in a desert area under ambient conditions using the current shunt measuring technique. Therefore, most of the problems encountered with traditional measuring techniques are avoided. The temperature dependency of the current shunt from 5ºC up to 50ºC has been investigated. Its temperature coefficient proves to be negligible which means that the temperature dependency of the solar cell is completely independent of the current shunt. The solar module installed in a tilted position at the optimum angle of the location, has been tested in two different seasons (winter and summer). The obtained solar cell short circuit current, open circuit voltage and output power are correlated with the measured incident radiation in both seasons and all results are discussed

An improved design of a fully automated multiple output micropotentiometer

This paper describes in details a new design of a fully automated multiple output micropotentiometer (?pot). A prototype has been built at the National Institute for Standards (NIS), Egypt to establish this highly improved AC voltage source in the millivolt range. The new device offers three different outputs covering a wide frequency range from only one outlet. This valuably supports the precise sourcing ranges of low AC voltage at NIS. The design and the operation theory of this prototype have been discussed in details. An automatic calibration technique has been introduced through specially designed software using the LabVIEW program to enhance the calibration technique and to reduce the uncertainty contributions. Relative small AC-DC differences of our prototype in the three output ranges are fairly verified. The expanded uncertainties of the calibration results for the three output ranges have been faithfully estimated. However, further work is needed to achieve the optimum performance of this new device

Electrical performance study of a large area multicrystalline silicon solar cell using a current shunt and a micropotentiometer

In this paper, a new technique using a Current Shunt and a Micropotentiometer has been used to study the electrical performance of a large area multicrystalline silicon solar cell at outdoor conditions. The electrical performance is mainly described by measuring both cell short circuit current and open circuit voltage. The measurements of this cell by using multimeters suffer from some problems because the cell has high current intensity with low output voltage. So, the solar cell short circuit current values are obtained by measuring the voltage developed across a known resistance Current Shunt. Samples of the obtained current values are accurately calibrated by using a Micropotentiometer (μpot) thermal element (TE) to validate this new measuring technique. Moreover, the solar cell open circuit voltage has been measured. Besides, the cell output power has been calculated and can be correlated with the measured incident radiation

On stability of discretizations of the Helmholtz equation (extended version)

We review the stability properties of several discretizations of the Helmholtz equation at large wavenumbers. For a model problem in a polygon, a complete $k$-explicit stability (including $k$-explicit stability of the continuous problem) and convergence theory for high order finite element methods is developed. In particular, quasi-optimality is shown for a fixed number of degrees of freedom per wavelength if the mesh size $h$ and the approximation order $p$ are selected such that $kh/p$ is sufficiently small and $p = O(\log k)$, and, additionally, appropriate mesh refinement is used near the vertices. We also review the stability properties of two classes of numerical schemes that use piecewise solutions of the homogeneous Helmholtz equation, namely, Least Squares methods and Discontinuous Galerkin (DG) methods. The latter includes the Ultra Weak Variational Formulation

Experimental Analysis on Double Layer Kapton Material using Peltier Thermoelectric Device

Kapton is one of the flexible materials used in the development of microwave components for the telecommunications system. The electrical properties of Kapton are dependent on the material's temperature. In this study, this material will be heated, and the electrical properties of dielectric permittivity and loss tangent will be analyzed. This material heating process is done by using Peltier thermoelectric which is installed with Aluminium alloy. The 0 V up to 7 V DC voltage was supplied to the Peltier during the heating process. Then, the electrical properties of Kapton were measured by using a dielectric probe and vector network analyzer (VNA) at frequencies of 1 GHz to 9 GHz. The results obtained show the Kapton temperature was increased from 27oC to 41oC. Meanwhile, the dielectric permittivity also varied from 1.72 to 1.64 at the frequency of 5 GHz when 4 V was used. The maximum loss tangent value of 0.5 was observed when the maximum DC voltage of 7 V was applied. The knowledge of this experimental work can be used to design reconfigurable microwave components for smart system application

A Fuzzy Inference System for Closed-Loop Deep Brain Stimulation in Parkinson’s Disease

Parkinsons disease is a complex neurodegenerative disorder for which patients present many symptoms, tremor being the main one. In advanced stages of the disease, Deep Brain Stimulation is a generalized therapy which can significantly improve the motor symptoms. However despite its beneficial effects on treating the symptomatology, the technique can be improved. One of its main limitations is that the parameters are fixed, and the stimulation is provided uninterruptedly, not taking into account any fluctuation in the patients state. A closed-loop system which provides stimulation by demand would adjust the stimulation to the variations in the state of the patient, stimulating only when it is necessary. It would not only perform a more intelligent stimulation, capable of adapting to the changes in real time, but also extending the devices battery life, thereby avoiding surgical interventions. In this work we design a tool that learns to recognize the principal symptom of Parkinsons disease and particularly the tremor. The goal of the designed system is to detect the moments the patient is suffering from a tremor episode and consequently to decide whether stimulation is needed or not. For that, local field potentials were recorded in the subthalamic nucleus of ten Parkinsonian patients, who were diagnosed with tremor-dominant Parkinsons disease and who underwent surgery for the implantation of a neurostimulator. Electromyographic activity in the forearm was simultaneously recorded, and the relation between both signals was evaluated using two different synchronization measures. The results of evaluating the synchronization indexes on each moment represent the inputs to the designed system. Finally, a fuzzy inference system was applied with the goal of identifying tremor episodes. Results are favourable, reaching accuracies of higher 98.7 % in 70 % of the patients.Centro de Investigación Biomédica en RedDepto. de Psicología Experimental, Procesos Cognitivos y LogopediaDepto. de Radiología, Rehabilitación y FisioterapiaFac. de PsicologíaFac. de MedicinaTRUEpu

Absolute Competence in the Fields of Alms in the Religious Courts

This research aims to investigate the absolute competence in the fields of alms in the Religious Court in Indonesia. The method used in this research is normative juridical research with the type of prescriptive analysis of research, namely studying the purpose of the law, the values of justice, the validity of the rule of law, legal concepts, and legal norms. This research found that the case of alms has never appeared. It can happen because alms cases are resolved through non-litigation. The settlement of alms disputes has likely been completed up to the zakat management institution's level, and alms has become part of Islam's teachings. It is necessary o cooperate with other institutions in resolving it legally. Besides that, there is a need for legislation that provides opportunities to solve alms' problem does not clash with its legal aspects

The state of ambient air quality in Pakistan—a review

Background and purpose: Pakistan, during the last decade, has seen an extensive escalation in population growth, urbanization, and industrialization, together with a great increase in motorization and energy use. As a result, a substantial rise has taken place in the types and number of emission sources of various air pollutants. However, due to the lack of air quality management capabilities, the country is suffering from deterioration of air quality. Evidence from various governmental organizations and international bodies has indicated that air pollution is a significant risk to the environment, quality of life, and health of the population. The Government has taken positive steps toward air quality management in the form of the Pakistan Clean Air Program and has recently established a small number of continuous monitoring stations. However, ambient air quality standards have not yet been established. This paper reviews the data being available on the criteria air pollutants: particulate matter (PM), sulfur dioxide, ozone, carbon monoxide, nitrogen dioxide, and lead. Methods: Air pollution studies in Pakistan published in both scientific journals and by the Government have been reviewed and the reported concentrations of PM, SO2, O3, CO, NO2, and Pb collated. A comparison of the levels of these air pollutants with the World Health Organization air quality guidelines was carried out. Results: Particulate matter was the most serious air pollutant in the country. NO2 has emerged as the second high-risk pollutant. The reported levels of PM, SO2, CO, NO2, and Pb were many times higher than the World Health Organization air quality guidelines. Only O3 concentrations were below the guidelines. Conclusions: The current state of air quality calls for immediate action to tackle the poor air quality. The establishment of ambient air quality standards, an extension of the continuous monitoring sites, and the development of emission control strategies are essential. © Springer-Verlag 2009