Problem Of Poor Reliability Research Articles

Research on Model Predictive Control Based on Sensorless Permanent Magnet Synchronous Motor

For permanent magnet synchronous motor (PMSM) speed control system, aiming at the problems of slow dynamic response and large dependence on system model parameters of traditional PI control of PMSM, the model predictive current control strategy is adopted to design the predictive model. Aiming at the problems of poor reliability and high cost of traditional permanent magnet synchronous motor with mechanical sensor, the speed sensorless control technology is introduced to design the control structure, and the rotor position and speed are estimated by sliding mode observer method. Through simulation verification, the results show that the combination of the above two control methods can obviously improve the performance of the traditional permanent magnet synchronous motor control system, and has strong robustness under the conditions of motor parameters and load changes.

Improvement and Application of Key Tools for Hydraulic Jet Fracturing

Aiming at the problems of poor reliability, low construction efficiency, and short service life of fracturing string in the application of hydraulic jet technology in Daqing Oilfield, targeted research has been carried out on key tools such as rubber cylinder, slip, and nozzle.A unidirectionally-sealing rubber cylinder adopting composite sealing method was designed. The rubber cylinder could bear the pressure of 80 MPa and temperature resistance of 150∘C under the setting force of 20 kN, with tensile strength increased by 23% and residual deformation rate less than 3%, showing good overall sealing performance and recovery. The finite element method was used to optimize the structural parameters, materials and process of the slip to increase the ability of slips to withstand alternating loads by 1.5 times. The arc-shaped nozzle was improved to reduce the pressure drop and increase the jet density. By improving the performance indicators of key tools, the optimized fracturing string could meet the construction requirements of low setting force, high sealing pressure difference, and repeated setting and fracturing. The improved technical string was applied to section 3459 of well 218 well in the field, with the success rate reaching 100%. The large-scale application of the improved fracturing string satisfied the construction requirements for large-scale volume fracturing of the for the 5 1/2" inch casing new well completion in the low-permeability and tight reservoirs of Daqing Oilfield.

Research on processing technology of beam membrane structure based on porous silicon

Aiming at the problem of poor reliability of beam membrane fabrication in silicon microstructure processing technology, a technique for preparing microbeams using porous silicon sacrificial layer is proposed. The comparison of different porosity, different depths of porous silicon to beam membrane release and the comparison of different beam structures to beam membrane release were studied. The experiment was carried out by selecting different process parameters and testing the prepared beam membrane. According to the test results, the appropriate electrochemical corrosion process parameters were selected to prepare the porous silicon layer with appropriate porosity, large depth, good support effect and fast release speed, which can realize the release of the beam membrane and improve the reliability of the beam membrane. The field of application of microsensors and microactuators has been greatly increased.

Finite Element Analysis of Motor Box for EBZ160 Horizontal Roadheader

In order to solve the cracking and poor reliability problems of motor box of Horizontal Roadheader, the static structural FEA (Finite Element Analysis) of cutting arm & motor box of the EBH160 Horizontal Roadheader was conducted, and the stress and strain contours of FEA were obtained. By comparing the calculated results, the safety factor of cutting arm & motor box was 1.36, which provides a reference for the optimal design of cutting arm & motor box.

Zigbee Technology in Intelligent Electric Leakage Protection System Applied Research

Aiming at inconvenient wiring and low flexibility of current wired sensor network,An implementation method for real-time monitoring system based on ZigBee wireless network is proposed in this paper. in view of existing selective earth leakage protection device of low sensitivity, poor reliability problems, proposed one kind based on the zero sequence current feature selectionSelective leakage protection and line selection method; analysis of power supply system leakage fault branch of zero-sequence current logical relations, introduced based on the zero sequence current featuresVolume selective leakage protection principle and the realization method of fault line selection.As a Zigbee wireless sensor technology, Its application to the grid. Analyze leakage protection system in relation to the past system of superior performance and favorable conditions, And its features and system design of a simple program to explain the analysis and application of specific measures. DOI: http://dx.doi.org/10.11591/telkomnika.v11i8.302 7

Impairments of Methodology and Theory in Cognitive Neuropsychology: A Case for Rehabilitation?

A common approach in studies of human cognition is to derive conclusions from the aggregate performance of groups of normal subjects. These group-based results are then used in the development of models of a cognitive architecture. What is often missed is that in many experiments there are some subjects who do not consistently show the pattern of results observed for the group as a whole. In this case, the aberrant pattern is often treated as random variation. The issue becomes more acute when the aberrant pattern of performance is obtained from single cases of patients with neurological damage. In this case however, the data are interpreted as indicative of some cognitive deficit, and their modification following a given treatment as indicative of the effect of that treatment. The aim of this study is to tackle the issue of random variation in normal control groups. We argue that one way to avoid biased results is to specify the generality and the reliability of normal group effects before attempting to apply them to neuropsychological patients. The point we want to stress is a broad one. However, to make this issue concrete we will discuss findings in the context of a specific area of cognition, namely, short-term verbal memory. To make our pointwe summarise some ofourownfindings from groupstudies in normal controls, and examine why some individuals, with no overt neuropathology, fail to show widely replicated, well-established phenomena linked with verbal short-term memory. In particular we focus on (1) the possible influence of memory span, (2) the effect of strategy choice, (3) the presence of control samples of subjects with possible hidden cerebral lesions, and (4) the problem of poor reliability. We conclude by arguing for the general importance of test-retest reliability, and of strategy choice in both clinical studies and theoretically driven studies of cognitive deficits.