Method for Determining the Schottky Diodes Electrical Parameters

When studying the operation of Schottky diodes the most important electrical parameters are the height of the potential barrier, the coefficient of ideality, the saturation current and the series resistance of the material and contacts. These parameters can be determined from the experimental volt-ampere characteristics. The article considers the methods of determining these electrical parameters of Schottky diodes, as well as the factors that affect the accuracy of calculations. The existing methods for calculating the electrical parameters of Schottky diodes are analyzed, namely: the method of Norde, Roderick, Chong, Sato and the method of direct approximation. The Norde method was developed for a coefficient of ideality equal to one for cases where the effect of series resistance on the I–V characteristics makes a significant error in determining the barrier height by simpler methods. A significant disadvantage of this method is that in many cases the coefficient of ideality is not equal to one, even in the case of an ideal diode, which makes an error in the calculation result. The advantage of Roderick's method is the possibility of describing the forward and reverse branches of the I–V characteristics by one dependence, as well as taking into account measurements at voltages less than tripled temperature potential. The disadvantages of this method include the lack of consideration of the effect of series resistance, which may result in additional errors. The main advantage of the Chong method is the determination of the series resistance together with the height of the barrier and the coefficient of ideality, which not only provides additional information about the contact, but also convenient in terms of automation of the calculation process. The disadvantages include the possibility of applying the method only to the voltage range above the tripled temperature potential. The disadvantages of Sato methods and direct approximation include the fact that the calculation is performed at one point of the I–V curve, which can negatively affect the accuracy. It is also shown that these methods have a significant standard deviation of the calculated values from the experimental ones, which is due to the temperature dependence of the height of the potential barrier and the dependence of the coefficient of ideality on the voltage. Also, the reason for the increase in the calculation error of the electrical parameters in all five methods is the decrease in the length of the I–V characteristics in logarithmic coordinates. When using any of the considered methods, the calculation is performed in logarithmic coordinates, which complicates the determination of the boundaries of the I–V section, where the dependence of the parameters of the Schottky diode on the voltage is insignificant. A new algorithm for calculating the electrical parameters of Schottky diodes has been developed. Based on the conjugate gradient method, a method for optimizing the algorithm for calculating the electrical parameters of Schottky diodes was developed, which made it possible to reduce the standard deviation by more than an order of magnitude. The developed algorithm is verified by comparing the calculated volt-ampere characteristics of Schottky diodes with those obtained experimentally. To construct the calculated volt-ampere characteristics, the values of the electrical parameters of Schottky diodes were used, which were determined by the presented algorithm. The results of the calculation are in good agreement with the experimental data. The proposed method can be used both in scientific work to study the properties of semiconductor materials, and in production to control the quality of Schottky diodes.

Computational study of a 3-step hybrid integrators for third order ordinary differential equations with shift of three off-step points

A Block of hybrid method with three off-step points based is presented in this work for direct approximation of solution of third-order Initial and Boundary Value Problems (IVPs and BVPs). This off-step points are formulated such that they exist only on a single step at a time. Hence, these points are shifted to three positions respectively in order to obtain three different integrators for computational analysis. These analysis includes; order of the methods, consistency, stability and convergence, global error, number of functions evaluation and CPU time. The superiority of these methods over existing methods is established numerically on different test problems in literature

Numerical modeling of ground-borne vibrations induced by pile driving with a simple and direct material damping approach

Ground-borne vibrations are an increasingly common problem in large cities due to its considerable disturbance in terms of human comfort and health. In this sense, construction operations stand as a significant source of vibrations and may be critical since construction sites are frequently adjacent to existing buildings. In the present work, vibrations induced by pile driving are studied. A time-domain finite element model is developed and a post-processing approach is proposed to simulate the material damping of the soil. This damping formulation stands as a simple and direct approximation of the material damping in the system. In order to do so, the numerical response is computed without material damping, which is introduced as a post-processing procedure. An explicit and highly efficient method is applied for the time integration of the equation of motion, considering an axisymmetric formulation. A numerical application is carried out and the obtained results are compared to previous numerical and in-situ measurements available in the literature, indicating a good agreement with previous studies.

Approximation on Manifold

The purpose of this work is to obtain an effective evaluation of the speed of convergence for multidimensional approximations of the functions define on the differential manifold. Two approaches to approximation of functions, which are given on the manifold, are considered. The firs approach is the direct use of the approximation relations for the discussed manifold. The second approach is related to using the atlas of the manifold to utilise a well-designed approximation apparatus on the plane (finit element approximation, etc.). The firs approach is characterized by the independent construction and direct solution of the approximation relations. In this case the approximation relations are considered as a system of linear algebraic equations (with respect to the unknowns basic functions ωj (ζ)). This approach is called direct approximation construction. In the second approach, an approximation on a manifold is induced by the approximations in tangent spaces, for example, the Courant or the Zlamal or the Argyris fla approximations. Here we discuss the Courant fla approximations. In complex cases (in the multidimensional case or for increased requirements of smoothness) the second approach is more convenient. Both approaches require no processes cutting the manifold into a finit number of parts and then gluing the approximations obtained on each of the mentioned parts. This paper contains two examples of Courant type approximations. These approximations illustrate the both approaches mentioned above.

Modern problems in assessment of hydraulic resistance

The paper is devoted to the analysis of modern problems in assessment of hydraulic resistance. The obtained formulas for calculating the roughness coefficients and other interrelated hydraulic parameters of the channel are given. As a determining factor for the systemic characteristics of flows, N.A. Rzhanitsyn used the average long-term and average maximum water discharges, and the authors of this work proposed the use of these characteristics in accordance with the watershed area A in km2 of the subsequently derived dependences for unexplored rivers. Thanks to this approach, it became possible to obtain information by cartographic methods. Direct approximation of these data gives an expression for the flow order. The formulas obtained can be used to calculate the hydraulic characteristics of lowland rivers. For the European territory of Russia, the formulas have been tested using independent field information. However, the authors believe that the formulas will successfully work for other even lands as well. The formulas are simple and easy to calculate using software. In the future, it is planned to use specialized software for processing calculations and use the obtained results in the geographic information system.

Wind Speed Distribution Direct Approximation by Accumulative Statistics of Measurements and Root-Mean-Square Deviation Control

In order to accurately estimate wind farm output and subsequently optimise it, a method of wind speed distribution approximation is suggested. The method is based on period-by-period accumulation of wind speed measurements, transforming them into empirical probabilities, and observing the moving approximation to the expected power produced by the wind turbine or entire wind farm. A year is a minimal term during which wind statistics are to be accumulated. The sufficient validity and reliability of the wind speed distribution approximation is supported by controlling root -mean-square deviations and maximal absolute deviations with respect to the moving average of the expected power. The approximation quality can be regulated by adjusting constants defining the requirements to the moving deviations.

Modeling the temperature shock of elastic elements using a one-dimensional model of thermal conductivity

This paper considers the task of evaluating micro-accelerations arising due to the temperature shock of large elastic elements when a small spacecraft leaves the Earth’s shadow. In this case, a one-dimensional model of thermal conductivity is used. Its solution was obtained by the method of direct approximation with the construction of difference schemes. It is shown that the accuracy of estimating micro-accelerations is commensurate with the accuracy of solving by a three-dimensional model of thermal conductivity. The proposed model allows reducing the time to obtain estimates and significantly simplifies the task at hand. The results of the work can be used in the formation of the dynamic characteristics of a small spacecraft for technological purposes.

Intercostal Nerve Transfers to the Musculocutaneous–A Reliable Nerve Transfer for Restoration of Elbow Flexion in Birth-Related Brachial Plexus Injuries

Introduction There is consensus on the need for early microsurgical reconstruction in birth palsies involving three or more roots, that is, extensive partial palsies and total palsies. The fundamental principles of these operations are complete exploration and judicious use of the ruptured stumps by nerve grafting to suitable distal targets. The frequent observation of root avulsions in such cases makes it imperative to look for extraplexual nerve donors for some functions. Intercostal nerves are readily available in such patients. Materials and Methods This is a study of 50 patients of extensive partial and total birth palsies operated upon by the senior author between 1995 and 2010. These included 33 patients with total palsies, 16 patients with near total palsies, and one patient with C56 deficit (operated upon more than 20 years ago). These children were all operated upon between 3 and 6 months of age, except for two patients in whom surgery was delayed till a year due to the phrenic nerve deficit noted at birth. Four intercostal nerves were transferred to the musculocutaneous nerve (MCN) by direct approximation with fibrin glue. Results No respiratory complication was noted from the intercostal harvest. The follow-up ranged from 8 to 20 years (mean 10 years). As many as 48 of the 50 patients regained fully independent elbow flexion. In two cases, the procedure failed completely and had to be salvaged with a free functioning muscle transfer and reuse of the intercostal nerves. Conclusion Intercostal nerve transfers can be relied upon for restoration of elbow flexion in birth palsies. The ruptured roots can then be utilized for augmenting shoulder function in partial palsies or for hand function in total palsies.

Direct and converse theorems for King operators

For the sequence of King operators, we establish a direct approximation theorem via the first order Ditzian-Totik modulus of smoothness, and a converse approximation theorem of Berens-Lorentz-type.