运营商需建立担保租机联动监管体系

近日,临沂联通兰山区分公司高姓副总自杀事件震惊业界。事实上,担保租机造成的恶性事件不是第一次出现了,前联通山东总经理就因担保租机而下课,现在临沂联通仍在采用员工担保租机这种营销方式。所谓担保租机一般有单位担保、资产担保、员工担保等方式,以单位担保租机为主。这本是一个好政策,既抢占了市场商机又给单位创造了价值,但在目前市场诚信意识不强的情况下,担保租机容易被人利用,只需要单位公章和个人身     

疏于管理和监管是悲剧主因

近日,有爆料称,临沂联通副总因担保租机欠费跳楼身亡,在惋惜之余,此事引发了业内对于零首付担保租机的争论。据笔者了解,所谓零首付担保租机政策早在几年前就已在各电信运营商中采用,而且其面向的多是大中型的政企用户。按理说,这种政策应该是运营商和用户都得利的事情,怎么会演变成今天的惨剧呢?不可否认,今天中国电信市场竞争相比几年前更加惨烈,之前频频曝出的校园营销中各运营商为争夺客户大打出手的事件便是明证。具体到零首付担保租机,估计运营商之间除了以优惠的名义打价格战之外,疏于管理和监管也是造成相关客户     

取消“零首付租机”四川联通实施营销新策略

本刊讯 日前，为贯彻联通总部CDMA营销模式转型的决策，加快业务转型步伐，更加有效地控制用户发展成本．联通四川分公司按照“CDMA手机销售必须保证现金流为正”、“补贴与手机终端脱钩．只与用户消费贡献挂钩”等原则．近期已全面停止任何形式的零首付租机及租CDMA1X上网卡业务。     

SA向中国国际广播电台环球广播卫星传输覆盖平台提供信源编码处理和光缆传输系统

国际台现有节目播出语言种类众多，随着对外落地广播不断增加，台外互转和租机落地节目已出现传输瓶颈问题，根据国际台现状和近期的发展需要，急需建立国际台环球广播节目卫星传输覆盖平台。     

数控地毯样机选纱系统研究

为适应快速化、智能化生产需求,在传统纺机选纱机构基础上,提出一种新型数控地毯样机的选纱系统。该系统上位机采用Visual Basic 6.0进行系统软件开发,实现地毯图案花型数据读取与转换等功能。下位机综合运用GALIL运动控制卡、接近开关、电磁阀等部件实现系统运动控制。结果证明,该系统可自动进行纱线选取与漏纱检测,准确高效,满足生产要求,提高了样品质量和生产速度。     

江苏省邮电无线寻呼在全省推出“租机”业务

江苏省邮电无线寻呼公司于1996年6月18日开始,统一在全省各邮电寻呼台开展租机     

台达变频器VFD-F在自动络筒机的节能应用

络筒机作为纺纱过程中的重要设备,近年来技术革新迅速。国外全自动络纱机在20世纪末已发展到第三代,具有精密卷绕、精密纺叠、精密定长、电子清纱、空气捻接、在线质量栓验及纱疵分级、节能降耗等特点。本文介绍了台达VFD-F变频器在自动络筒机负压风机节能上的应用。     

粗暴经营何时休?

日前,某地运营商发生了管理人员跳楼的恶性事件。据传,事情源于所谓的"员工担保租机"营销活动——运营商内部员工提供信用担保,消费者可以以此与运营商签订最低消费协议,只需每月按照协议承诺,按照不同档次的终端缴纳不同档次的最低消费额度,就可以获得零元(或象征性的一元)的租机。这种营销政策看似可实现运营商、员工与消费者的共赢,但却存在严重风险——如果消费者出现欠费,提供担保的员工则需代为履行缴费义务,而追讨欠费的工作往往也由员工自身完成,对于经济能力有     

提供双模手机 开通美国漫游——中国移动GSM巩固漫游优势

继开通韩国漫游租机业务后,近日,中国移动又与美国NEXTEL公司合作,开通了美国国际漫游出访业务。很显然,在中国联通新时空CDMA网络运营后,中国移动为了不至于因漫游“缺憾”而输给     

小灵通租机业务有什么优势？

小灵通租机业务是福建电信利用省智能网系统在省内各本地网范围内开放的一种在宾馆、酒店等代办点以租赁方式向用户提供小灵通终端实现实时计费、结算功能的业务。     

Visual Attentive Interfaces

Context-aware human-computer interfaces that rely on a person's attention as the primary input can be called attentive interfaces. Attention is epitomised by eye contact — eyes are not only scanning devices, they are constantly making social commentary by how people gaze as well. Concentrating on the autonomic and social responses that eyes communicate allows eye tracking to drive attentive interfaces. Eye-based attentive interfaces can be improved by noting the way people scan objects and take advantage of the lingering stare, roving gaze, and nervous blink in a language of ocular attention. Even simple sensors are able to deduce many of these social cues.     

压电贾卡高速响应驱动电路设计与研究

为了适应贾卡经编机机速超过1 500 r/min以上的发展趋势，通过分析经编机对压电贾卡驱动电路驱动贾卡导纱针偏移响应时间的要求，提出了一种高速响应的压电贾卡驱动电路设计方案。对该设计方案中的硬件选址，光电隔离，串入并出和200 V快速开关驱动等主要模块的设计进行详细阐述。在压电贾卡空载状态下的实验测试结果表明，该电路对阶跃信号具有高速的跟踪能力，在频率为35 Hz下，经编机机速为2 100 r/min时能实现快速响应，压电贾卡工作正常。安装在RSJ5/1经编机上进行实际工作测试，结果表明可满足经编机高机速的要求。     

A start-up method for a speed sensorless stator-flux-orientedvector-controlled induction motor drive

This paper describes a zero-speed start-up method of a speed sensorless stator-flux-oriented direct vector-controlled induction motor drive with the help of a machine current model that does not use any speed signal. The machine starts smoothly with vector control at finite developed torque and then transitions to the standard direct vector-control mode with the voltage model signals as the speed begins to develop. The direct vector-control mode with voltage model uses programmable cascaded low-pass filters for flux-vector synthesis and enables the drive to operate from zero speed to field-weakening mode. As the drive speed falls to zero, the drive again transitions to start-up mode, so that it can be smoothly started again. The performance of the start-up scheme has been verified on a 100 kW electric vehicle drive     

On the behavior of a current fed synchronous machine drive withoutDC-link inductance

A drive system with synchronous machine and machine-commutated thyristor-inverter is discussed. The current source of this type of drive is realized by a fast switching transistor chopper, and the current is smoothed by the machine reactance and, atypically, by a choke in the DC link. It is shown that operation without link inductance affects the margin angle of the inverter. Hence, the reactive power of the machine has to be increased considerably. To overcome this disadvantage, a special method of control is presented, investigated, and verified by experimental results     

欧瑞变频器在造纸机传动系统中的应用

文章应用欧瑞E2000系列通用变频器和西门子S7-200P LC组成的基于RS485通讯的文化纸机传动控制系统,通过软、硬件设计,较好的实现了造纸机传动控制系统中的负荷分配、速度链、张力控制等功能。现场应用验证,这种基于S7-200PLC和欧瑞E2000系列变频器的全数字控制系统适用中、高速纸机的速度、可靠性等控制性能的需要,获得了满意的控制效果。     

Online estimation of the stator resistance and leakage inductance of a four-phase induction machine drive

This paper proposes a technique to determine online the stator resistance and the stator leakage inductance of a four-phase induction machine in a four-phase drive system. These parameters are obtained by solving a least squares minimization problem. The technique is conceived to be used online with the drive strategy without disturbing the machine electromagnetic torque. Experimental results are used to demonstrate the feasibility of the proposed technique.     

Machine/drive circuit interactions in small variable-reluctancestepping and brushless DC motor systems

The authors investigate the torque, losses, and efficiency of small brushless DC and stepping-motor systems, and explain how performance is influenced by excitation mode, drive circuit, and machine parameters. Quantitative deductions are made for a three-phase reluctance-type machine based on computed steady-state results. For a given machine and drive circuit, maximum torque is obtained with an excitation mode that allows each phase to be turned on for half of the complete excitation cycle. However, if maximum efficiency is the aim, phase excitation must occur for a shorter period, e.g. by exciting only one phase at a time. When making comparisons between drive circuits, the most important measure of drive-circuit capability is the circuit power available at low speeds. Drive circuits producing rapid current decay at phase turn-off benefit torque production in the two-phase-on excitation mode, but are detrimental with the one-phase-on mode. At high speed the pull-out torque depends on the unsaturated inductance parameters of the machine. For maximum torque these parameters must be correctly proportioned, their values being dependent on the excitation mode     

柴油发电机组DSP控制系统人机界面设计

文章采用以ST7920为控制器的点阵式液晶,设计了应用于柴油发电机组控制的人机界面,给出了DSP芯片TMS320F2812与液晶模块的硬件接口电路。软件的编写采用模块化方法,分为驱动层、功能层和应用层三个部分。其中驱动层为面向硬件的底层驱动程序。功能层是以底层驱动为基础编写的中层功能函数,最后通过应用层对功能函数的调用完成了人机界面的菜单设计。     

变频调速技术在粗纱机上的应用

本文主要介绍了变频调速技术在粗纱机上的应用概况，论述了粗纱机采用4电机传动的效果。介绍了粗纱机控制系统原理框图以及共直流母线的变频渊速。     

Dynamic and Vibration Analysis of a Multimotor DC Drive System With Elastic Shafts Driving a Tissue Paper Machine

In this paper, the influence of the stiffness and damping of real elastic shafts on the behavior of a multidrive system driving a tissue paper machine is investigated. The drive system consists of four DC motors, where two of them drive the Yankee drying cylinder and the other two drive the presses section. Six-pulse thyristor bridge power converters that are connected to the same power transformer supply the motors. The inertias of the motors and the driven machines, in conjunction with the shaft stiffness, form mechanical resonators. Thus, resonance phenomena may occur, which may lead to undesirable results. This particular case results to two three-mass and one five-mass systems. This paper presents an analysis of the resonance frequencies of two sections of the machine during startup and machine production, considering the shaft stiffness (shaft diameter, length, and thickness). The elastic shafts eliminate the ripple of the motor electromagnetic torque, which is transferred to the driven machine. The behavior of elastic shafts with different stiffness in the transmission system is studied. Moreover, the steady state and dynamic behavior of the system considering the influence of the elastic shafts and vibration analysis were investigated using simulation. A model algorithm for system simulation was developed using the MATLAB/SIMULINK software. Characteristic simulation results are presented and are expressed in terms of speed and torque response. Considering the resonance frequency analysis and simulation results, mechanical design guidelines can be given for the most significant drive components in order to avoid torsional oscillation resonance phenomena and minimize torsional oscillations of the drive system.