scholarly journals EARM: An Efficient and Adaptive File Replication with Consistency Maintenance in P2P Systems

2012 ◽  
pp. 5-9
Author(s):  
K. V. K. Chaitanya ◽  
S. Vasundra
Keyword(s):  
System Performance ◽  
Low Cost ◽  
Time Varying ◽  
Consistency Maintenance ◽  
P2p Systems ◽  
Maintenance Mechanism ◽  
Query Efficiency ◽  
Simulation Results ◽  
File Replication ◽  
Message Propagation

In p2p systems, file replication and replica consistency maintenance are most widely used techniques for better system performance. Most of the file replication methods replicates file in all nodes or at two ends in a clientserver query path or close to the server, leading to low replica utilization, produces unnecessary replicas and hence extra consistency maintenance overhead. Most of the consistency maintenance methods depends on either message spreading or structure based for update message propagation without considering file replication dynamism, leading to inefficient file update and outdated file response. These paper presents an Efficient and Adaptive file Replication and consistency Maintenance (EARM) that combines file replication and consistency maintenance mechanism that achieves higher query efficiency in file replication and consistency maintenance at a low cost. Instead of accepting passively file replicas and updates, each node determines file replication and update polling by adapting to time-varying file query and update rates. Simulation results demonstrate the effectiveness of EARM in comparison with other approaches.

Study and design of dual stator permanent magnet machine with spoke-type configurations using phase-group concentrated-coil windings

2020 ◽  
Vol 64 (1-4) ◽  
pp. 1381-1389
Author(s):  
Dezhi Chen ◽  
Chengwu Diao ◽  
Zhiyu Feng ◽  
Shichong Zhang ◽  
Wenliang Zhao
Keyword(s):  
Permanent Magnet ◽  
Permanent Magnets ◽  
Low Cost ◽  
Dynamic Performance ◽  
Torque Ripple ◽  
Permanent Magnet Machine ◽  
Torque Density ◽  
Phase Group ◽  
High Torque ◽  
Simulation Results

In this paper, a novel dual-stator permanent magnet machine (DsPmSynM) with low cost and high torque density is designed. The winding part of the DsPmSynM adopts phase-group concentrated-coil windings, and the permanent magnets are arranged by spoke-type. Firstly, the winding structure reduces the amount of copper at the end of the winding. Secondly, the electromagnetic torque ripple of DsPmSynM is suppressed by reducing the cogging torque. Furthermore, the dynamic performance of DsPmSynM is studied. Finally, the experimental results are compared with the simulation results.

An Analysis on the Forming Load of AA 2024 Aluminium Alloy in Combined and Sequence Operation Process

2006 ◽  
Vol 519-521 ◽  
pp. 949-954 ◽  
Author(s):  
Beong Bok Hwang ◽  
J.H. Shim ◽  
Jung Min Seo ◽  
H.S. Koo ◽  
J.H. Ok ◽  
...  
Keyword(s):  
Finite Element ◽  
Load Capacity ◽  
Low Cost ◽  
Forming Load ◽  
Mechanical Press ◽  
Combined Operation ◽  
Aa 2024 ◽  
Load Characteristics ◽  
Simulation Results ◽  
Selection Of

This paper is concerned with the analysis of the forming load characteristics of a forward-backward can extrusion in both combined and sequence operation. A commercially available finite element program, which is coded in the rigid-plastic finite element method, has been employed to investigate the forming load characteristics. AA 2024 aluminum alloy is selected as a model material. The analysis in the present study is extended to the selection of press frame capacity for producing efficiently final product at low cost. The possible extrusion processes to shape a forward-backward can component with different outer diameters are categorized to estimate quantitatively the force requirement for forming forward-backward can part, forming energy, and maximum pressure exerted on the die-material interfaces, respectively. The categorized processes are composed of combined and/or some basic extrusion processes such as sequence operation. Based on the simulation results about forming load characteristics, the frame capacity of a mechanical press of crank-drive type suitable for a selected process could be determined along with securing the load capacity and with considering productivity. In addition, it is suggested that different load capacities be selected for different dimensions of a part such as wall thickness in forward direction and etc. It is concluded quantitatively from the simulation results that the combined operation is superior to sequence operation in terms of relatively low forming load and thus it leads to low cost for forming equipments. However, it is also known from the simulation results that the precise control of dimensional accuracy is not so easy in combined operation. The results in this paper could be a good reference for analysis of forming process for complex parts and selection of proper frame capacity of a mechanical press to achieve low production cost and thus high productivity.

Gyro Drift Calibration in Low Cost Inertial System

1999 ◽  
Author(s):  
Zhong Zhao ◽  
Rong Ma ◽  
Weiguo Zhang
Keyword(s):  
Low Cost ◽  
Fuzzy Reasoning ◽  
Calibration Method ◽  
Inertial System ◽  
Time Varying ◽  
Dynamic Estimation ◽  
Gyro Drift

Abstract An intelligent gyro drift calibration method for low-cost inertial system is presented in this paper. This method based on fuzzy reasoning and dynamic estimation can calibrate time-varying gyro drift in the motion of vehicle. Experiments have been done on three strapdown inertial all-attitude systems constituted of piezoelectric rate gyros. The result shows that this method is effective by which the residual of piezoelectric gyro drift can be reduced to about one percent of its original drift value.

Optimal Control of a Flexible Mechanism Using a Combined Feedforward-Feedback Strategy: Simulation and Experiment

1999 ◽  
Author(s):  
Hubertus v. Stein ◽  
Heinz Ulbrich
Keyword(s):  
Optimal Control ◽  
Control Strategy ◽  
System Performance ◽  
High Speed ◽  
Time Varying ◽  
Linkage Mechanism ◽  
Additional Degree ◽  
Control Approach ◽  
Feedback Optimal Control ◽  
Four Bar Linkage

Abstract Due to the elasticity of the links in modern high speed mechanisms, increasing operating speeds often lead to undesirable vibrations, which may render a required accuracy unattainable or, even worse, lead to a failure of the whole process. The dynamic effects e.g. may lead to intolerable deviations from the reference path or even to the instability of the system. Instead of suppressing the vibration by a stiffer design, active control methods may greatly improve the system performance and lead the way to a reduction of the mechanism’s weight. We investigate a four-bar-linkage mechanism and show that by introducing an additional degree of freedom for a controlled actuator and providing a suitable control strategy, the dynamically induced inaccuracies can be substantially reduced. The modelling of the four-bar-linkage mechanism as a hybrid multi body system and the modelling of the complete system (including the actuator) is briefly explained. From the combined feedforward-feedback optimal control approach presented in (v. Stein, Ulbrich, 1998) a time-varying output control law is derived that leads to a very good system performance for this linear discrete time-varying system. The experimental results show the effectiveness of the applied control strategy.

scholarly journals Time-Varying Impedance Control of Port Hamiltonian System with a New Energy-Storing Tank

Complexity ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Min Zheng ◽  
Tangqing Yuan ◽  
Tao Huang
Keyword(s):  
Control Method ◽  
Impedance Control ◽  
Conservative System ◽  
Time Varying ◽  
Control Performance ◽  
Singularity Problem ◽  
Numerical Examples ◽  
New Energy ◽  
Simulation Results ◽  
New Framework

In order to guarantee the passivity of a kind of conservative system, the port Hamiltonian framework combined with a new energy tank is proposed in this paper. A time-varying impedance controller is designed based on this new framework. The time-varying impedance control method is an extension of conventional impedance control and overcomes the singularity problem that existed in the traditional form of energy tank. The validity of the controller designed in this paper is shown by numerical examples. The simulation results show that the proposed controller can not only eliminate the singularity problem but can also improve the control performance.

Iterative learning algorithm with a quadratic criterion for linear time-varying systems

2002 ◽  
Vol 216 (3) ◽  
pp. 309-316 ◽  
Author(s):  
S N Huang ◽  
K K Tan ◽  
T H Lee
Keyword(s):  
Learning Algorithm ◽  
Linear Time ◽  
Tracking Error ◽  
Iterative Learning ◽  
Tracking Performance ◽  
Time Varying ◽  
Control Scheme ◽  
Time Varying Systems ◽  
Simulation Results ◽  
Learning Law

A novel iterative learning controller for linear time-varying systems is developed. The learning law is derived on the basis of a quadratic criterion. This control scheme does not include package information. The advantage of the proposed learning law is that the convergence is guaranteed without the need for empirical choice of parameters. Furthermore, the tracking error on the final iteration will be a class K function of the bounds on the uncertainties. Finally, simulation results reveal that the proposed control has a good setpoint tracking performance.

scholarly journals Ultrasound detection using optical interferometry

2021 ◽  
Author(s):  
Nusrat Jahan Surovy
Keyword(s):  
Thin Film ◽  
Ultrasound Imaging ◽  
Detection System ◽  
Incidence Angle ◽  
Low Cost ◽  
3D Ultrasound ◽  
Attractive Alternative ◽  
Simulation Results ◽  
Exerted Pressure ◽  
Piezoelectric Devices

Ultrasound imaging is a widely used noninvasive imaging technique for biomedical and other applications. Piezoelectric devices are commonly used for the generation and detection of ultrasound in these applications. However, implementation of two-dimensional arrays of piezoelectric transducers for 3D ultrasound imaging is complex and expensive. Optical Fabry-Perot interferometry is an attractive alternative to the piezoelectric devices for detection of ultrasound. In this method a thin film etalon is constructed and used. Light reflected from the two surfaces of this thin film produces an intensity which depends on the film thickness. When ultrasound is incident on the film, it changes the thickness of the film and consequently modulates the light intensity on the film. In our work, we made two types of etalon (Finesse 2) for our experiment. We detected lower frequency ultrasound (0.5 MHz or 1 MHz) using the build etalon. We determined a linear relationship between the strength of the optical signals and the exerted pressure on a film by the ultrasound. The dependence of the etalon performance on the light wavelength was demonstrated indirectly by measuring the signal at various light incidence angle. Simulation results are also presented. Lastly, we proposed the optimum design of this detection system based on the simulation results. This method of ultrasound detection can be a potential low-cost approach for 3D ultrasound imaging.

Sign in / Sign up

Export Citation Format

Share Document