变频器在矿山设备耐压检测中的应用

对传统试验变压器调压方法与矿山设备现场耐压绝缘检测需要进行分析,指出传统试验变压器匝数多、体积大、检测周期长等缺点,不利于矿山设备现场耐压绝缘测试的诸多弊端.通过对变压器调压的数学模型分析,创新性地提出将传统变匝数参数改变为变频参数,同时利用电工技术中串联谐振电路原理,设计出变频器式试验变压器,方便了矿山设备的绝缘耐压检测.     

编码器对ACS6000双驱变频控制的作用和影响

本文阐述了ACS6000型双驱变频器中编码器的工作原理，并结合米拉多铜矿磨机系统应用ACS6000型双驱变频器时发生的问题现象，分析了编码器对电机直接转矩控制和变频器功率计算的作用和影响。     

交联聚乙烯绝缘电力电缆超低频耐压试验方法

对电缆主绝缘进行耐压试验是考核电缆绝缘状况,保证电力电缆安全运行的重要手段。本文着重介绍了0.1Hz超低频正弦波耐压试验技术及运用这一技术的耐压测试设备及方法。     

WK-35电铲下盘分离变频驱动控制装置的应用

分析了大修电铲在上下盘举升分离后,应用相同功率的2台低压变频器供电,分别独立控制下盘左右行走电机,实现下盘行走驱动变频调速,并对变频器驱动电铲交流电机的特性曲线进行了分析探讨,为选定变频器型号提供了依据。     

变频调速渣浆泵的电压选择

对于特定功率段的变频器,既可以采用低压(380 V)也可以采用中压(10 kV),如何选择应进行技术经济比较.本文以实际工程为例,通过比较两种电压的初始投资费用和运行费用,根据综合费用最优的原则选择变频器电压.     

弹性波测试技术在巷道围岩松动圈测试中的应用

弹性波测试技术在工程测试中的应用是非常普遍的，本文了利用弹性波测试技术探测巷道围岩松动圈的原理与工作方法，并对某巷道围岩松动圈的测试结果进行了比较详细的分析讨论，开展围岩松动圈的测试研究，可以为巷道支护方法试验提供依据。     

判断变频器修复质量的1种实用方法

以ALSPA MV1000系列变频器为例,在离线模式下接入220V、50 Hz的交流电源,利用白炽灯作为负载,通过手动方式运行变频器,能够比较简单直接地判断修复变频器的好坏。该方法为生产现场提供了1种变频器的简易测试技术,减少了利用检修时间拆除和安装变频器的繁琐过程,对机组的正常运行不会带来任何危害。     

Ad Hoc网络功率功耗测试优化设计

对Ad Hoc网络功率功耗进行优化测试,降低网络系统功耗,提高系统的寿命和可靠性。传统方法中对Ad Hoc网络功率功耗测试方法采用基于统计特征的信道检测方法,受到信道的干扰较为严重,功耗测试准确性不好。提出一种基于混叠谱特征分析的Ad Hoc网络功率功耗测试方法。构建Ad Hoc网络模型和功率检测算法,然后进行功率谱的混叠谱特征提取和分析,实现对Ad Hoc网络功率功耗测试优化。仿真实验表明,采用该方法进行Ad Hoc网络功耗测试,结果准确,降低网络的功率损失,提高网络寿命和稳定性。     

国产高压变频器在新技术烧结中的应用

介绍了国产高压变频器在烟气循环中的应用。详细描述了烟气循环节能、减排原理,并通过风机风量、功率、转速之间的关系说明了使用变频器的节能原理和整个变频系统的组成及该变频器的工作原理。结果表明,高压变频器在烟气循环系统中运行稳定可靠,能够实现主抽和烟气循环的流量合理分配,同时节能效果显著。     

中压变频器在大H型钢精轧机中的应用

文章介绍了ABB中压变频器(ACS6000)在包钢轨梁厂的成功应用,详细描述了ACS6000 SD系统主要的功率模块单元。结合ACS6000 SD中压变频器在大H型钢线精轧机同步电动机调速传动控制上的应用,对ACS6000中压变频器及直接转矩控制等先进技术在同步电动机上的应用特点进行了说明。     

Test Review.

The College Entrance Examination Board sponsors the subject of this review, the Comparative Guidance and Placement Program. Aside from the test booklet and answer sheet, the published materials associated with the Comparative Guidance and Placement Program are as follows: CGP--What it's like, Using your CGP report, CGP--A program for two-year colleges and vocational-technical institutes, CGP Interpretive Manual, and A counselor's guide to CGP. This review discusses the various inputs, outputs, psychometric characteristics, and student use of the Comparative Guidance and Placement Program. After making comments on the Comparative Guidance and Placement Program, the reviewer questions just what the utility of the Comparative Guidance and Placement Program is for the student, and question whether it has any for the college which uses it. The decision to use the program should be made thoughtfully. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Test review.

Describes the administration and scoring of the Personal Orientation Inventory (POI), developed by E. L. Shostrom, to measure values and behavior considered by therapists to be important for self-actualization. A review of POI reliability and concurrent validity is presented. The POI is criticized for the following reasons: (a) the decision that POI Time Competence and Inner-Directed Support subscales are the variables most basic to self-actualization is an arbitrary one, (b) traits defined as self-actualizing are culture-specific, (c) neither the therapist nor the client standardization sample is described, and (d) no distinctions are made between the concepts of self-actualization and mental health. It is concluded that the POI may be used as a therapeutic device to facilitate personal exploration of life style but is of limited value as either a diagnostic or research instrument. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Test Review.

Reviews the American College Testing Program (1972 Edition) assessment device for the guidance of students enrolled in 2-year colleges and institutes. Issues addressed include testing mechanics, the Career Planning Program Profile (construction and content), reliability, predictive validity, concurrent validity, the Counselor's Manual, and the Student Booklet. It is concluded that the amount of information returned to the student is large and carefully planned, that interpretation of the profile by a guidance counselor would be imperative, and that the level of difficulty of the extensive material presented in the Handbook is high. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

水产养殖知识考试系统随机组卷算法的实现

水产养殖知识考试系统基于浏览器/服务器结构,采用基于随机算法抽题,试题库中的试题以单个试题的形式存放且不形成成套试卷,按题型、难度、区分度、题分、知识点等分别进行分类管理.考生按考题要求完成通用浏览器向服务器传送,该系统使用类和对象对考生上传的文件进行实例化,从中读取相应属性进行判分,再把最终分数写入考生成绩数据库中.     

Online Reading Test Evaluation

Language test has been used as a scientific assessment tool in providing valuable information for teaching and learning. In fact,lots of online reading tests are not designed with validity. This paper analyzes those online reading tests from the aspects o     

连翘叶水提取物对小鼠急性毒性和微核试验

[目的]研究连翘叶水提取物对小鼠急性毒性、致突变性作用,[方法]采用最大给药量试验进行连翘叶水提取物急性毒性试验,给药后连续观察7 d、记录动物反应情况.观察结束后对小鼠进行剖检、血液学检查和生化检查,以小鼠骨髓嗜多染红细胞微核试验进行致畸变检测.[结果]小鼠最大给药量折合生药为60 000 mg/kg;在此剂量下小鼠无明显异常表现,内脏病理解剖无器官病变情况,体重、血液、生化指标与正常对照组无明显差异;微核试验呈阴性反应.[结论]连翘叶水提取物为无毒性物质,亦无致突变作用,经口给药可安全用于兽医临床.     

Beck Self-Concept Test.

The development and psychometric characteristics of the Beck Self-Concept Test (BST) are described. The BST is a 25-item self-report instrument that asks respondents to evaluate themselves in relation to other people whom they know. An item analysis with 550 psychiatric outpatients diagnosed primarily with DSM-III—R mood or anxiety disorders indicated that all of the BST's items were significantly correlated with the corrected total scores; the coefficient alpha was .82, indicating good internal consistency. The 1-week and 3-month test–retest reliabilities were .88 and .65, respectively. The BST was significantly related to the Rosenberg Self-Esteem Scale and displayed both discriminant and convergent validities with respect to measures of psychopathology. (PsycINFO Database Record (c) 2010 APA, all rights reserved)