Experimental Analysis of Radial Centrifugal Pump Shutdown

Centrifugal pumps are widely used in the metallurgy,coal,and building sectors.In order to study the hydraulic characteristics of a closed impeller centrifugal pump during its shutdown in the so-called power frequency and frequency conversion modes,experiments were carried to determine the characteristic evolution of parameters such as speed,inlet and outlet pressure,head,flow rate and shaft power.A quasi-steady-state method was also used to further investigate these transient behaviors.The results show that,compared to the power frequency input,the performance parameter curves for the frequency conversion input are less volatile and smoother.The characteristic time is longer and the response to shutdown is slower.The quasi-steady-state theoretical head-flow curves match the experimental head-flow curves more closely at low flow rates when the frequency conversion input is considered.Moreover,in this case,the similarity law predicts the hydraulic performance more accurately.

Simulation Method and Feature Analysis of Shutdown Pressure Evolution During Multi-Cluster Fracturing Stimulation

Multistage multi-cluster hydraulic fracturing has enabled the economic exploitation of shale reservoirs,but the interpretation of hydraulic fracture parameters is challenging.The pressure signals after pump shutdown are influenced by hydraulic fractures,which can reflect the geometric features of hydraulic fracture.The shutdown pressure can be used to interpret the hydraulic fracture parameters in a real-time and cost-effective manner.In this paper,a mathematical model for shutdown pressure evolution is developed considering the effects of wellbore friction,perforation friction and fluid loss in fractures.An efficient numerical simulation method is established by using the method of characteristics.Based on this method,the impacts of fracture half-length,fracture height,opened cluster and perforation number,and filtration coefficient on the evolution of shutdown pressure are analyzed.The results indicate that a larger fracture half-length may hasten the decay of shutdown pressure,while a larger fracture height can slow down the decay of shutdown pressure.A smaller number of opened clusters and perforations can significantly increase the perforation friction and decrease the overall level of shutdown pressure.A larger filtration coefficient may accelerate the fluid filtration in the fracture and hasten the drop of the shutdown pressure.The simulation method of shutdown pressure,as well as the analysis results,has important implications for the interpretation of hydraulic fracture parameters.

WINDOWS95使用随笔——中文视窗九五关于DELE、V-FAT、SHUTDOWN的说明

一、怎样删除WINDOWS 95系统 常有电脑爱好者询问:WIN95出故障后,如何将其在DOS下删除?为什么有故障而不能再次进行WIN95的安装呢?或怎样正确进行WIN95的删除呢? 先说说发烧友的一个普遍不良习惯,这就是找到一个新的软件,不管三七二十一,先装进计算机再说,如果遇到问题,不去查阅操作手册,而是凭着平时的所谓“专业知识功底”删掉再装。

A polyethylene microsphere-coated separator with rapid thermal shutdown function for lithium-ion batteries

Thermal runaway is the main factor contributing to the unsafe behaviors of lithium-ion batteries(LIBs)in practical applications.The application of separators for the thermal shutdown has been proven as an effective approach to protecting LIBs from thermal runaway.In this work,we developed a thermal shutdown separator by coating a thin layer of low-density polyethylene microspheres(PM)onto a commercial porous polypropylene(PP)membrane and investigated the thermal response behaviors of the as-prepared PM/PP separator in LIBs.The structural and thermal analysis results revealed that the coated PM layer had a porous structure,which facilitated the occurrence of normal charge-discharge reactions at ambient temperature,although it could melt completely and fuse together within very short time periods:3 s at 110℃and 1 s at 120℃,to block off the pores of the PP substrate,thereby cutting off the ion transportation between the electrodes and interrupting the battery reaction.Consequently,the PM/PP separator exhibits very similar electrochemical performance to that of a conventional separator at ambient temperature.However,it performs a rapid thermal shutdown at an elevated temperature of^110℃,thus controlling the temperature rise and maintaining the cell in a safe status.Due to its synthetic simplicity and low cost,this separator shows promise for possible application in building safe LIBs.

Reliability Analysis on Repairable System with Dual Input Closed-Loop Feedback Link Considering Shutdown Correlation Based on Goal Oriented Methodology

Goal oriented( GO) methodology is a kind of success oriented system reliability analysis method and has been used widely.The repairable system with dual input closed-loop feedback link( DICLFL) considering shutdown correlation didn't make reliability analysis accurately based on existing GO methodology. So, a reliability analysis method used to deal with DICLFL considering shutdown correlation is provided based on GO methodology.Firstly, a new operator, which is used to describe DICLFL considering shutdown correlation,whose number is 1,is created and named as Type 9C operator. And then,the formulas of type 9C operator are derived based on Markov process theory. Finally,the new method presented in this paper is adopted to conduct the reliability analysis of an electro-hydraulic servo speed control system. The analysis result is compared with those of Monte Carlo simulation and fault tree analysis( FTA). The comparison results show that this new reliability analysis method based on GO methodology is feasible and meaningful for reliability analysis of repairable systems with DICLFL considering shutdown correlation.Meantime,it will be useful for more other applications.

Neutronic design investigation of a liquid injection-based second shutdown system for a typical research reactor using MCNPX

Safety systems, built on state-of-the-art technology, are essential for achieving acceptable levels of plant safety to minimize hazards to the reactor and the general public. The second shutdown system(SSS) as an engineered safety feature and a part of the reactor protection system(RPS) is a means for rapidly shutting down a nuclear reactor, keeping it in a subcritical state and serving as a backup to the first shutdown system(FSS). In this research, one SSS with two types of optimum chamber designs is proposed that take into account the main current characteristic features of the Tehran research reactor with improvements over earlier designs. They are based on a liquid neutron absorber injection that is preferably different, diverse, and independent from the FSS based on the rod drop mechanism. The major design characteristics of this SSS with two different chambers were investigated using MCNPX 2.6.0 code. The performed calculations showed that the designed SSS is a reliable shutdown system, assuring an appropriate shutdown margin and injection time, with no significant effects on the effective delayed neutron fraction while causing minimal variations to the core structure. Further, the reasonable financial cost and the prolongation of the operation cycle are additional advantages of this design.

Implementation and application of PyNE sub-voxel R2S for shutdown dose rate analysis

PyNE R2S is a mesh-based R2S implementation with the capability of performing shutdown dose rate(SDR)analysis directly on CAD geometry with Cartesian or tetrahedral meshes.It supports advanced variance reduction for fusion energy systems.However,the assumption of homogenized materials of PyNE R2S with a Cartesian mesh throughout a mesh voxel introduces an approximation in the case where a voxel covers multiple non-void cells.This work implements a sub-voxel method to add fldelity to PyNE R2S with a Cartesian mesh during the process of activation and photon source sampling by performing independent inventory calculations for each cell within a mesh voxel and using the results of those independent calculations to sample the photon source more precisely.PyNE sub-voxel R2S has been verifled with the Frascati Neutron Generator(FNG)-ITER and ITER computational shutdown dose rate benchmark problems.The results for sub-voxel R2S show satisfactory agreement with the experimental values or reference results.PyNE sub-voxel R2S has been applied to the shutdown dose rate calculation of the Chinese Fusion Engineering Testing Reactor(CFETR).In conclusion,sub-voxel R2S is a reliable tool for SDR calculation and obtains more accurate results with the same voxel size than voxel R2S.

雷神二次雷达shutdown故障的诊断与分析

本文阐述了非核心部件"shutdown保护性关机"造成雷达系统单通道关闭,以及对此故障进行诊断分析。

施耐德电气全新升级PowerChute^(TM) Network Shutdown软件以支持虚拟集群环境

全球能效管理专家施斛德电气宣布推出Power Chute^TM Network Shutdown软件V3．1版。该软件是一款基于网络的服务器关机解决方案外级版，具备更强的虚拟化支持功能。

施耐德电气全新升级PowerChute Network Shutdown

中国北京，2014年2月18日——近日，全球能效管理专家施耐德电气宣布推出PowerChute Network Shutdown软件V3．1版（PowerChute Network Shutdown v3．1）。该软件是一款基于网络的服务器关机解决方案升级版，具备更强的虚拟化支持功能。

Shutdown命令关机失效

Q 我的Windows 7系统以前可以使用诸如：at 23：00 shutdown-s的命令来倒计时关机，现在使用该命令却不行了。请问这是什么原因？

施耐德电气全新升级PowerChute Network Shutdown软件以支持虚拟集群环境

2014年2月18日，全球能效管理专家施耐德电气宣布推出PowerChuteTM Network Shutdown软件V3．1版（PowerChuteTM Network Shutdown v3．1）。该软件是一款基于网络的服务器关机解决方案升级版，具备更强的虚拟化支持功能。PowerChuteTM Network Shutdown软件V3．1版扩展了虚拟化功能，

shutdown关机命令详解

相信shutdown-a命令很多人都用过，但详细的关机指令相信没多少人会，下面笔者给大家说一下shutdown的一些关机指令。

指名道姓：ShutDown 夜深了，用它守护你的电脑

有时我们需要在无人值守的情况下开着电脑，比如半夜下载电影，一般都是使用自动关机软件来解决问题，但自动关机软件大多只是按照指定时间来关机，并不精确，很容易出现误关机带来麻烦。ShutDown则是一款功能更为强大和灵活的自动关机软件，它的特点就是可以根据CPU占用率、窗口标题、窗口关闭等变化来执行自动关机操作，从而更为精确的满足自动关机需要。

基于UEFI固件的Windows Abnormal Shutdown问题分析

简要介绍了UEFI固件的组成及Windows操作系统的历史,详细介绍了导致Windows Abnormal Shutdown问题的原因及基于UEFI固件的分析造成这个原因的方法,并给出了部分程序代码。

Dynamic Responses of A Semi-Type Offshore Floating Wind Turbine During Normal State and Emergency Shutdown

This paper addresses joint wind-wave induced dynamic responses of a semi-type offshore floating wind turbine(OFWT) under normal states and fault event conditions. The analysis in this paper is conducted in time domain, using an aero-hydro-servo-elastic simulation code-FAST. Owing to the unique viscous features of the reference system, the original viscous damping model implemented in FAST is replaced with a quadratic one to gain an accurate capture of viscous effects. Simulation cases involve free-decay motion in still water, steady motions in the presence of regular waves and wind as well as dynamic response in operational sea states with and without wind. Simulations also include the cases for transient responses induced by fast blade pitching after emergency shutdown. The features of platform motions, local structural loads and a typical mooring line tension force under a variety of excitations are obtained and investigated.

Activation and shutdown dose-rate analyses for the EAST NBI test facility

An analysis of the neutron activation and shutdown dose rates was performed for the EAST high-power deuterium neutral beam injector test facility(EAST NBITF) by using the multiparticle transport code FLUKA2011.2. Also, the neutron and neutron-induced gamma spectra of the facility's vacuum vessel were evaluated. The results identified the major radionuclides^(99) Mo,^(65)Ni,^(58) Co,^(56)Mn, and^(51) Cr for the vacuum vessel and the primary nuclide^(64) Cu for both the ion dump and the calorimeter.The simulated results indicated that, when the EAST NBITF operates within the design parameters of deuterium energy 80 ke V, current 50 A, and pulse 100 s, the neutron intensity will achieve 10^(11)n/s with no radiation safety problems after the EAST NBITF shuts down.

Hybrid Dynamic Modeling and Control of Molten Carbonate Fuel Cell Stack Shutdown

A hybrid automaton modeling approach that incorporates state space partitioning, phase dynamic modeling and control law synthesis by control strategy is utilized to develop a hybrid automaton model of molten carbonate fuel cell (MCFC) stack shutdown. The shutdown operation is divided into several phases and their boundaries are decided according to a control strategy, which is a set of specifications about the dynamics of MCFC stack during shutdown. According to the control strategy, the specification of increasing stack temperature is satisfied in a phase that can be modeled accurately. The model for phase that has complex dynamic is approximated. The duration of this kind of phase is decreased to minimize the error caused by model approximation.