Effect Of Statistical Variations Research Articles

Four quadrant analog multiplier based memristor emulator using single active element

This paper presents a novel Four Quadrant Analog Multiplier (FQAM) circuit and its applications using a single active element Current Differencing Transconductance Amplifier (CDTA) and two NMOS. This circuit has a cascadability feature as it produces current and voltage outputs at high and low impedance ports, respectively. It offers additional features such as resistor-less realization, operability in voltage and trans-conductance mode, and configurable structure. Further, the FQAM circuit is configured to develop a memristor emulator based on the proposed mathematical analogy. The proposed memristor circuit contains active elements (one CDTA, two NMOS, and one Inverting Voltage buffer) and only one grounded capacitor. It offers tunability using the transconductance gain of the CDTA block. Also, the proposed memristor emulator circuit doesn’t contain any additional multiplier block. The emulator circuit can be operated in both the Incremental and the Decremental mode of memristance variation. The results demonstrate the non-volatile property as well as hysteresis behavior for the wide frequency range. The effects of statistical variation in passive component, threshold voltage, and aspect ratios on the proposed circuits using Monte-Carlo simulation have been estimated. Also, the impact of non-idealities and the parasitic effects of the CDTA on the proposed circuits are investigated. In last, the capacitor-less version of the memristor emulator and its hysteresis characteristics have been demonstrated. The simulation results obtained using HSPICE, are agreed well with the theoretical analysis.

An analytical study on the effects of strain gradient on the fracture statistics of quasi-brittle materials

A deterministic model with material strain-softening has been employed to predict the failure process of quasi-brittle materials subjected to different strain gradients. The failures of beams in pure bending and L-shape specimens in tension are simulated using this model, and the influence of material damage rate on the failure process is studied. The effect of statistical variations in the material properties on the fracture statistics of the components is then considered. The model correctly predicts the changes in the magnitude and distribution of the failure loads of specimens with different strain gradients. The results can help explain the influence of strain gradient on the fracture statistics of quasi-brittle materials.

Application of Fractional Derivatives in Thermal Analysis of Disk Brakes

This paper presents a Fractional Derivative Approach for thermal analysis of disk brakes. In this research, the problem is idealized as one-dimensional. The formulation developed contains fractional semi integral and derivative expressions, which provide an easy approach to compute friction surface temperature and heat flux as functions of time. Given the heat flux, the formulation provides a means to compute the surface temperature, and given the surface temperature, it provides a means to compute surface heat flux. A least square method is presented to smooth out the temperature curve and eliminate/reduce the effect of statistical variations in temperature due to measurement errors. It is shown that the integer power series approach to consider simple polynomials for least square purposes can lead to significant error. In contrast, the polynomials considered here contain fractional power terms. The formulation is extended to account for convective heat loss from the side surfaces. Using a simulated experiment, it is also shown that the present formulation predicts accurate values for the surface heat flux. Results of this study compare well with analytical and experimental results.

Autonomous beam alignment for coherent Doppler lidar with multielement detectors

Autonomous beam alignment for coherent Doppler lidar requires accurate information about optical misalignment and optical aberrations. A multielement heterodyne detector provides the required information without a loss in overall system performance. The effects of statistical variations from the random backscattered field (speckle field) are determined with computer simulations for both ground-based operation with a fixed calibration target and for space-based operation with random target backscatter.

The Experimental Study of CODASYL Database Administration at the Secondary Storage Level

Five issues of CODASYL database administration are investigated in this paper. First, the effects of CODASYL storage record placement strategies on the cost of query and update transactions are investigated. Second, the cost of CODASYL database usage pattern is analysed and it is shown that for different usage patterns, different optimal storage structures result. Third, the effects of some changes on an optimal storage structure which the designer may consider desirable are investigated. Fourth, the benefits of clustering storage records which are hierarchically related by CODASYL sets are analysed and shown to decrease with the increase in the levels of the hierarchy. Finally, the effects of statistical variation that may be expected in data populations on the cost of query and update transactions are examined.

Effect of thermodynamic fluctuations on the shape and width of the resistive transition in three-dimensional amorphous superconducting alloys

Measurements of the fluctuation conductivity above ${T}_{c}$ have been made for several bulk amorphous superconducting alloys. The results are compared to existing theories for fluctuation conductivity in three-dimensional superconductors. Agreement with theory is obtained very near ${T}_{c}$, but significant deviations from the predictions of the theory are found for higher temperatures. This is attributed to a breakdown of the Ginzburg-Landau approach. The observed temperature dependence of the fluctuation conductivity was similar in all samples studied and suggests a universal dependence on temperature for bulk amorphous superconductors. The effect of statistical variations in alloy composition (occurring on the scale of the superconducting coherence length $\ensuremath{\xi}$ on the width of the superconducting transition widths was observed.

Defect analysis and yield degradation of integrated circuits

Various attempts have been made to analyze the yield of integrated circuits in the presence of point defects. This paper analyzes the yield considering both radial and angular variation in the defect density. The effect of statistical variations in the average defect density from slice to slice is also included. Different types of defects which affect the yield are reviewed. The degradation in yield due to point defects, line defects, area defects, and defect clusters is considered in detail. A method of optimum chip placement is described, and the results of computer calculations showing yield as a function of chip size are given assuming different defect density distributions. The results are primarily applicable to large integrated circuit chips.

The effect of statistical variations in grid winding pitch upon the performance of a planar triode

The effect of statistical variations in the pitch of the grid winding of a triode valve is to produce an apparent increase in the `variable-mu' constant. Formulae are developed by which the magnitude of this effect may be calculated.

Load-Rating Theory for Multichannel Amplifiers

The amplifiers of multichannel telephone systems must be so designed with regard to output capacity that interchannel interference caused by amplifier overloading will not be serious. Probability theory is applied to this problem to determine the maximum single-frequency output power which a multichannel amplifier should be designed to transmit as a function of N, the number of channels in the system. The theory is developed to include the effects of statistical variations in the number of simultaneous talkers, in the talking volumes, and in the instantaneous voltages from speech at constant volume.

Load Rating Theory for Multi-Channel Amplifiers*

The amplifiers of multi-channel telephone systems must be so designed with regard to output capacity that interchannel interference caused by amplifier overloading will not be serious. Probability theory is applied to this problem to determine the maximum single frequency output power which a multi-channel amplifier should be designed to transmit as a function of N, the number of channels in the system. The theory is developed to include the effects of statistical variations in the number of simultaneous talkers, in the talking volumes, and in the instantaneous voltages from speech at constant volume.