Effect Of Load Variation Research Articles

Using Regression Techniques to Predict Large Data Transfers

The recent proliferation of Data Grids and the increasingly common practice of using resources as distributed data stores provide a convenient environment for communities of researchers to share, replicate, and manage access to copies of large datasets. This has led to the question of which replica can be accessed most efficiently. In such environments, fetching data from one of the several replica locations requires accurate predictions of end-to-end transfer times. The answer to this question can depend on many factors, including physical characteristics of the resources and the load behavior on the CPUs, networks, and storage devices that are part of the end-to-end data path linking possible sources and sinks. Our approach combines end-to-end application throughput observations with network and disk load variations and captures whole-system performance and variations in load patterns. Our predictions characterize the effect of load variations of several shared devices (network and disk) on file transfer times. We develop a suite of univariate and multivariate predictors that can use multiple data sources to improve the accuracy of the predictions as well as address Data Grid variations (availability of data and sporadic nature of transfers). We ran a large set of data transfer experiments using GridFTP and observed performance predictions within 15% error for our testbed sites, which is quite promising for a pragmatic system.

The performance of a medium ring transmission line at steady state

Abstract This paper presents the performance of the ring connection in transmission systems for medium lengths of a line under steady state operation. This will have more significant value especially if the transmitted power is a bulk amount. The ring connection between the phases of single circuit transmission in the form of cumulative connection (capacitive/inductive) impedance is accounted. The mathematical analysis is derived on the basis of Π equivalent circuit. The improvement of transmission performance is tried concerning the power factor either leading or lagging and loads. The earth path effect on transmission line parameters (resistance, inductance and capacitance) is included through the phase shift control. The medium length for such lines on the basis of sequential ring connection impedances is tested. The effect of load variation is investigated with the appearance of the shunt capacitive stray currents due to the increased length of the line. The ring allocation as a ratio of the total line length is tested. The node voltages and branch currents of the sending (first) and ring as well as the receiving (second) circuits are computed. Active and reactive powers at both sending and receiving ends of the proposed system are evaluated and then the transmission efficiency is determined. The effect of load impedance in the per-unit system is studied and resulting variation in the transmission capability is deduced.

Crack closure and effect of load variation on small fatigue crack growth behaviour : Jono, M. and Sugeta, A. Fatigue Fract. Eng. Mater. Struct. (1996) 19 (2–3), 165–174

A variable-amplitude block-loading history consisting of high, near-yield-stress, underloads or compression-tension overloads followed by constant-amplitude small cycles was used to examine underload and compression-tension overload induced reductions in crack closure and the subsequent build-up of crack-opening stress to its steady-state level in a 2024-T351 aluminium alloy. Special attention was given to the near-threshold region, where the crack growth rate was less than 10−9 m cycle−1 The crack-opening stress level and the crack growth rate were measured for four different R-ratios of the small cycles following underloads and compression-tension overloads using a 900 power short focal length optical microscope. The crack-opening stress levels were measured at frequent intervals after the underload and compression-tension overload applications until the crack-opening stress returned to a steady-state level. The crack-opening stress build-up was then described by an empirical formula in terms of the ratio of the difference between the instantaneous crack-opening stress of the small cycles (Sop) and the post-underload and compression-tension overload crack-opening stress levels (Sopol), and the difference between the steady-state crack-opening stress of the small cycles (Sopss) and the post-underload and compression-tension overload crack-opening levels, (Sop− Sopol)(Sopss−Sopol). Effective stresses calculated using this formula were used to predict crack growth rates. The formula's predictions showed good agreement with experimentally measured crack growth rates. For simplicity, both underloads and compression-tension overloads will be referred to as overloads in the remainder of this paper.

窒化けい素における一定および非定常変動振幅荷重下の疲労き裂進展挙動

In order to investigate the effect of load variation on the cyclic fatigue crack growth behavior of gas-pressure-sintered silicon nitride, fatigue crack growth tests under constant amplitude loading, multiple peak overloading, Lo-Hi and Hi-Lo two-step loadings were carried out using compact type (CT) specimens. Crack length and macroscopic crack closure were measured using the unloading elastic compliance method. Grain interlocking was observed around crack wake in all fatigue test specimens by SEM. Fatigue crack growth rate, da/dn, under constant amplitude loading was controlled by not only maximum stress intensity factor, Kmax, but also load amplitude. Crack opening stress intensity factor, Kop, decreased as load amplitude increased, as was concerned with breaking of grain interlocking. Overload caused the acceleration of fatigue crack growth rate, which was in contrast to the retardation observed in metallic materials. The acceleration was due to the breaking of grain interlocking by overload. The crack growth rate recovered as crack grew in a relatively short distance after overload, because grain interlocking in crack wake was reconstructed during crack growth.

Distribution system voltage and reactive power control based on probabilistic load flow analysis

The paper presents a method for the adjustment of voltage and reactive power control devices in distribution networks based on probabilistic constrained load flow. The overall control problem is decoupled into subproblems characterised by the reaction speed of the control devices. The algorithm takes into account the effects of load variations within the time period considered, and provides setpoints for control devices satisfying constraints for the whole planning period.

Prediction Method of Elastic-Plastic Fatigue Crack Growth Rate under Variable Amplitude Loadings.

Load-controlled fatigue crack growth tests were carried out under reversed and pulsating repeated variable amplitude loadings in post-yield region. Crack growth increment and crack closure were measured by the minicomputer-aided unloading elastic compliance method. The effects of load variation on the elastic-plastic fatigue crack growth behavior and the application of range-pair counting method to j-integral, ΔJ*, for estimation of crack growth rates, where both one-directional and cyclic plastic deformation were observed remarkably, was discussed. It was found that fatigue crack growth rates under reversed varying loadings were estimated by the linear summation rule based on ΔJ*, and fracture mechanics parameter ΔJ*/(1-Jmax/C), where Jmax is the maximum J-integral, should be used for estimation of growth rates of fatigue cracks where residual one-directional plastic deformation occurred as was observed under pulsating varying loadings.

Dynamic state estimation of power system harmonics using Kalman filter methodology

A Kalman filter is used to obtain the optimal estimate of the power system harmonic content. The measurements are simulated by adding Gaussian noise to the power system voltage and line flows at different harmonies obtained from a harmonic load flow program (HARMFLO). The effect of load variation over a one day cycle on the power system harmonics and standard are presented. The test results on the IEEE 14 bus system are included. The main difference in this approach from static estimation methods is that this method is dynamic and has the capability of tracking harmonic content versus time. >

New improved bipolar and bilateral voltage to current converters

Some improved bipolar, bilateral voltage-source-to-current-signal converter schemes, using operational amplifiers (OA) as active devices, are described. Some of them are derived from an earlier scheme that uses the OAs in summing mode, and the others are derived from the conventional technique of using the OAs in current output configurations. Except for one scheme that uses a single OA for the realization, the others have ideal voltage-to-current transfer ratio and characteristics. The realization constraints in each case have considerable degrees of flexibility, and there is no effect of load variation as long as the OAs used in the schemes are not saturated due to increased input conditions. The admittance matrices, constraints of realizations, and sensitivity to passive parameters for the different schemes are tabulated for ready reference. It is shown that the schemes can be used as V-I and I-V converters with scaling facility of the conversion factors. >

Effect of Load Variation on Surface Durability of Tufftrided Roller

Effect of Load Variation on Surface Durability of Tufftrided Roller

Study on Bending Fatigue Strength of Helical Gears : 5th Report, Effect of Load Variation on Bending Fatigue Strength

This paper presents a study on the effect of load variation on the bending fatigue strength of helical gears. A bending fatigue testing machine for cylindrical gears controlled by a micro computer was developed, and the bending fatigue tests of helical gears were carried out under a uniform cyclic load and a varying load which had the load spectrum of normal distribution. Various cumulative fatigue damage rules (Miner's rule, modified Miner's rule and VDI-Richtlinien 2151) were compared on the basis of the experimental results, and the effect of load variation on the bending fatigue strength of helical gears was clarified to a considerable extent. Furthermore the effect of understress on the bending fatigue life was investigated.

Effect of Load Variation on Surface Durability of Normalized Steel Roller

Effect of Load Variation on Surface Durability of Normalized Steel Roller

Effect of load variation on surface durability of tufftrided roller.

本論文は,一様および二段変動荷重条件下における軟窒化ローラの面圧強度特性について検討を加えたものである.本実験の硬化層深さの範囲では軟窒化ローラの面圧疲労限度は調質鋼ローラの2倍程度であり,また硬化層深さの増大につれて増加する傾向を示すこと,累積繰返し数比は荷重条件によって大きく変化するため軟窒化ローラの面圧強度設計にマイナーの仮説を直接適用することには問題があることなどが明らかになった.

Effect of Load Variation on Surface Durability of Normalized Steel Roller

Effect of Load Variation on Surface Durability of Normalized Steel Roller

The force-velocity relation and stepwise shortening in cardiac muscle.

A series of experiments was carried out to determine the effects of load variation on the character of stepwise shortening. We imposed afterloaded isotonic contractions on rat ventricular trabeculae, and measured the effect of load on pause duration, i.e., on the duration of the periods during which there was no sarcomere shortening. Sarcomere lengths were measured by optical diffraction. Increases of load brought about increases of pause duration; the relation was linear. The relation did not appear to depend on time during contraction, but did depend on sarcomere length: for a given load, pauses were longer at shorter sarcomere lengths. In a supplementary protocol in which we measured the dynamics of the central segment of the muscle during muscle isometric contraction, we found that the velocity of sarcomere shortening during the shortening step was approximately independent of load. These results provide a framework for interpretation of muscle force-velocity relations: diminished velocity at high load may be the result of increased pause durations.

The Effect of Load Variations on the Input Impedance of Electrical Machines

The Effect of Load Variations on the Input Impedance of Electrical Machines

The Design and Analysis of a Servovalve With Flow Feedback

Almost all conventional servovalves operate on the principle of controlling the position of a four-way or three-way valve made with very high precision with the hope that the flow rate will follow accurately the input signal to the valve. In this paper, an entirely new approach to the servovalve design is presented. A flow signal instead of valve position is used in the feedback loop. This design eliminates the necessity of a high precision valve, gives a greater length of the life expectancy of the valve, and minimizes the effect of load variation as well as supply pressure variation. Dynamic analysis and test results of the flowmeter and the complete valve are given.

Effect of Load Variation on the System Planning

Effect of Load Variation on the System Planning