A liquid helium temperature target with a 10 K vapor shield for shock compression experiment in the environment condition of 100 Pa

The shock compression experiment of liquid helium is an available way to gain properties of specimen at high temperatures and pressures.Based on Fluent,a thermal insulation analysis and design of a liquid helium temperature target in the environment condition of 100 Pa for shock compression experiment is performed.Then,a cryogenic target with a 10 K helium vapor shield and a separated vacuum interval is particularly developed.A lowest temperature of 3.63 K and a stable temperature of 3.70 K in the specimen cavity with an accuracy of 0.1 K are obtained by means of continuous flow and vacuum cooling.Both time-consuming and temperature stability are well-suited to the requirements of the shock compression experiment.The results show that the calculated and experimental data well-matched each other.The simulation method may be effective and feasible for the optimal design of the cryogenic target.     

Ho∞-based fault detection for nonlinear networked systems with random packet dropout and probabilistic interval delay

The fault detection problem for the nonlinear networked control system (NCS) with packet dropout and delay is investigated.A nonlinear stochastic system model is proposed to account for the NCS with random packet dropout and networkinduced non-uniformly distributed time-varying delay in both from sensor to controller (S/C) and from controller to actuator (C/A).Based on the obtained NCS model,employing an observer-based fault detection filter as the residual generator,the addressed fault detection problem is converted into an auxiliary nonlinear H∞ control problem.Then,with the help of Lyapunov functional approach,a sufficient condition for the desired fault detection filter is constructed in terms of certain linear matrix inequalities,which depend on not only the delay interval but also the delay interval occurrence rate and successful packet communication rate.Especially,a trade-off phenomenon between the maximum allowable delay bound and successful data packet transmission rate is found,which is typically resulted from the limited bandwidth of communication networks.The effectiveness of the proposed method is demonstrated by a simulation example.     

A new approach of available transfer capability incorporating wind generation

The approach of available transfer capability (denoted as ATC) incorporating wind generation has been paid very high attention since the development of wind generation. Based on the maximum function, this paper presents an ATC model. The characteristic of the new model is twofold. First, it considers wind turbines connected to power system and static security of power system simultaneously. Second, it is a system of semismooth equations and can be solved easily. By using the smoothing strategy, a smoothing Newton method is adopted for solving the proposed new ATC model. Numerical simulation results of the IEEE 30-bus and 118-bus system show that the new model and algorithm are feasible and effective. The impact of wind turbines connected to power system on ATC is also analyzed.     

浅谈工程招标采用最低价中标法的可行和可控

最低价中标法是国际上通用的工程招投标评标方法,过去中国政府一直限制这种方法的应用.2000年1月1日开始实施的<中华人民共和国招标投标法>首次允许招标人可以选择最低报价者中标,从法律上为该方法在中国的应用带来转机.可这种评标办法在带来益处的同时也带来弊端,文章从可行和可控两个方面对最低价中标法进行剖析.     

清单计价模式下工程项目全过程造价管理研究

文章通过介绍工程量清单计价模式的基本概念、基本原理,引入了全过程造价管理等概念,对工程量清单计价模式下的工程造价活动进行了较为深入细致的分析,并且就工程项目各个阶段的造价管理进行了具体的阐述.     

高层建筑施工管理应注意的事项及对策

经济发展对土地的利用率要求不断提高,高层建筑在城市建设中也越来越多,从写字间到居民住宅都可以看到高层建筑的身影。针对高层建筑的施工管理也随之成为建筑施工管理中的重点课题。本文试对高层建筑的施工管理进行分析,以资参考。     

基于差分自回归移动平均模型、长短期记忆网络模型及相关模型的无人机俯仰角预测

为了提高无人机俯仰角故障数据处理和预测的精确性和可靠性,避免增加无人机试飞成本,利用长短期记忆网络（Long Short Term Memory,LSTM）、注意力机制+LSTM模型和差分自回归移动平均模型（Autoregressive Integrated Moving Average Model,ARIMA）模型预测无人机试飞俯仰角故障数据。结果表明,ARIMA预测结果：MAE（Mean Absolute Error）=0.35,RMSE（Root Mean Square Error）=0.73,MAPE(Mean Absolute Percentage Error)=23.80%;LSTM模型预测结果：MAE=0.49,RMSE=0.74,MAPE=45.20%;注意力机制+LSTM模型预测结果：MAE=0.17,RMSE=0.53,MAPE=18.93%。可见注意力机制+LSTM模型比其余两种模型更适合于试飞俯仰角的数据预测,以上三种方法对无人机故障数据预测都具有实际意义,有效的预测可以推进自动飞行器和移动机器人的异常检测或外国直接投资研究的最新进展,以进一步提高自动和远程飞行操作的安全性。     

面向环形管道的电力巡检机器人设计与环境建图

在大型水电站中,离相封闭母线（isolated phase enclosed bus, IPB）只能通过预防性试验对设备状态进行检查,难以目视外观检查。为解决这种密闭狭小空间的环形管道的巡检困难问题,提出了一种可在水平、竖直段上行走的轮式攀爬机器人。首先,对攀爬机器人移动和附着方式进行对比分析,根据实际工况,选用轮式推力附着方式并基于该方式对机器人整体结构进行力学分析;通过搭建的模拟IPB管道内的运动实验,结果验证了巡检机器人满足水电站内IPB管道的检修需求且具有良好的适应性;设计基于柱坐标的点云配准方法,解决了管道内无法正确建图的问题,且计算时间优于激光雷达里程计建图 (lidar odometry and mapping, LOAM)及迭代最近点 (iterative closest point, ICP)算法,拓展了激光雷达点云建图的应用范围。     

宁州之设置与南中郡县制的反复——魏晋南北朝时期滇东北政区制度的演变

公元280年晋灭东吴后全国分为十九州,宁州居其一。此后300年间,国家陷于分裂,朝代更替频繁,政区变化无常;宁州郡县在中原王朝的军事监护与地方大姓的武力割据之间反复震荡;两汉及蜀国400年苦心经营建立的郡县制,终因豪强坐大而崩溃,郡县名号虽载于版籍,而行政制度无所施行。曾是经济繁荣、文化先进,号称＂宁州冠冕＂的朱提地区,社会发展也因此跌入低谷,历经了千年之久的停滞,直至明清时期才逐渐复苏。     

加强民办高校仪器设备管理的探讨

民办高校的仪器设备是从事教学、科研的重要条件和基本手段,是民办高校培养合格人才,促进学科建设,提高办学效益的物质基础,是学校综合实力的体现。通过对仪器设备管理的现状及存在问题的探讨,提出了加强民办高校仪器设备管理的措施与对策。