查询词典 instability constant

The working process and situation of the tube of constant current tube scanning circuit is introduced, which provides theoretic foundation for confirming the working situation of constant current tube .

本文论述了恒流管扫描电路管子的工作过程及工作状态，为确定恒流管的工作状态提供了理论依据。

The principle and current loop dynamic response are analyzed for both constant frequency current mode control and newly presented quasi-constant frequency hysteresis PWM control, experiments have been carried out to proof the analysis.

文中对现有的固定频率电流模式控制方法和所提出的准固定频率PWM电流控制方法的原理和闭环响应进行了分析，并通过实验证实了分析的正确性。

A novel quasi-constant frequency hysteresis PWM control approach is presented in this paper. Frequency feedback is introduced in hysteresis current control to stabilize switching frequency. Comparing with the common used constant frequency current mode control, the new approach has better stability, faster transient and higher precision, as well as elimination of sub-harmonic oscillation.

摘 要：本文提出了一种新的准固定频率滞环PWM电流控制方法，该方法在滞环电流控制的基础上，引入频率反馈控制，使开关频率基本固定，解决了目前广泛使用的固定频率电流控制方法具有的次谐波振荡的问题，并且具有稳定性好、相应速度快、控制精度高的优点。

Quasi-constant torque control is used when the speed is lower than 125 km/h,and constant power control is applied when the speed is higher than 125 km/h.

在速度低于125km/h采用准恒转矩控制，速度高于125km/h采用恒功率控制。

Quasi-constant torque control is used when the speed is lower than 125 km/h, and constant power control is applied when the speed is higher than 125 km/h. Direct rotor flux oriented control system is employed and three-level neutral point clamped traction inverter with SVPWM control is adopted.

在速度低于125km/h采用准恒转矩控制，速度高于125km/h采用恒功率控制，采用直接转子磁场定向控制系统，牵引逆变器采用空间电压矢量控制的带中点钳位二极管的三电平拓扑结构。

Locomotive characteristics of constant current quasi-constant speed control mode, can be a good start to play the greatest traction locomotives, locomotives equipped with air switch / slide protection system, the transfer axle load compensation control, wheel-rail lubrication system, automatic train safety monitoring device.

机车采用恒流准恒速的特性控制方式，能较好地发挥机车最大起动牵引力，机车装有防空转／滑行保护系统、轴重转移补偿控制、轮轨自动润滑系统、列车安全监控装置。

Its main production environment testing, the mechanical material testing equipment, main products have Standard / Programmable constant temperature and humidity machine, walk-in constant temperature and humidity room, the aging chamber, hot and cold impact testing machines, vibration test machine, drop test machine, compression tension tester, salt spray test machine, ultraviolet radiation, rain test chamber, sand and dust and all kinds of oven chamber, but also according to customer demand for design and production of non-standard environmental testing equipment and various types of large-scale trial into the climate Room.

其主要生产环境试验、力学材料试验设备，主要产品有标准型/可程序恒温恒湿机、步入式恒温恒湿室、老化试验箱、冷热冲击试验机、振动试验机、跌落试验机、压拉力试验机、盐雾试验机、紫外光照、淋雨试验箱、砂尘试验箱及各类干燥箱，还可根据客户的需求设计生产非标环境试验设备及各类大型步入气候试验室。

"Kv ·= constant" principle, a sense of freedom laminated springs and valve switching power systems Plug Valves constitute △ P / S =εL S-feeling film work area,ε-spring Hook coefficient, L-valve stroke From this position of valve travel decisions every size of △ P value, if the valve travel position of the Kv and inversely proportional to the G = Kv · a constant value.

&Kv·=常数&原理，自由弹簧和感压膜构成阀门开关动力系统△P/S=εL S—感膜工作面积，ε—弹簧的胡克系数，L—阀行程由此可知阀门的每一个行程位置决定△P值的大小，如果阀行程位的Kv与成反比，则G=Kv·是恒定值。

This design uses AT89C51 SCM chip controls the charging process, achieving A/D convert and show circuit. The battery voltage information can be detected by the external circuit to choose the correct charge mode, realizing the intelligent conversion mode of the trickle charge, the constant current charging, the constant voltage charging and the float charge.

采用AT89C51单片机芯片作为充电过程的控制芯片进行电路设计，实现A/D转换和显示电路，并根据外部电路检测到的电池电压信息选择正确的充电模式，实现在涓流、恒流、恒压及浮充电模式之间的智能转换。

Precise measurement of the Newtonian gravitational constant G plays important roles in the fields of the gravitation, geophysics, astrophysics, and cosmology. A torsion balance with timeof-swing method to determine the gravitational constant G is proposed.

Torsion balance ；万有引力常数G的精确测量不仅对于弄清引力相互作用的性质非常重要，而且对于整个理论物理学、地球物理学、天文学和宇宙学等都具有重要意义。

Objective To investigate the relationship between ovum fertilization rate and sperm morphology, acrosome reaction in IVF and to explore the influence of parameters of sperm on fertilization rate.

目的 研究体外受精(in vitro fertilization，IVF)中精子形态、顶体反应与卵子受精率之间的关系，分析精子各参数在IVF受精率方面的参考意义。

A: I hear Mr. White wants to run for the Presidency!

我听说怀特先生要参加总统竞选！