查询词典 mathematical constant

To accelerate the widespread of Synchronous Chip Seal and improve the operation quality of Synchronous Chipsealer, key techniques which influence the operation quality is studied detailedly, including the control of distributing quality, the dynamics characteristics of hydraulic system and the spray characteristics of asphalt nozzle of Synchronous Chipsealer.1 The factors which influence Synchronous Chip Seal quality are studied. Fiducial probability of simultaneous distribution density is advised to be used in evaluating the distribution bias and standard deviation of asphalt and aggregates simultaneously, which is more advanced than the single index evaluation method used before.2 The volume efficiency formula of asphalt pump is revised after analyzing the data of volume efficiency with mathematical statistics, which is helpful to match the asphalt spray system and control the flow out of asphalt pump accurately. With equation deduction and experiment, dynamic of hydraulic system used in Synchronous Chipsealer is studied, which lay the theory foundation on improving the stability and efficiency from design and controlling.4 Simulation on hydraulic system used in Synchronous Chipsealer is done with AMESim; the results indicate that multi-circle parallel connected hydraulic system with constant pressure power is better than that with load-sensing pressure power at present, because the latter will oscillate when the multi circles work at the same time. This conclusion has been proved during the debug of Synchronous Chipsealer.5 Asphalt nozzle characteristics, such as flat jet shape, flow distribution, are studied with experiment, the results indicate that cross quality of asphalt distributing is not increased linearly follow the increase of fan overlap level, the best point usually exists between two whole overlap level, asphalt distributing quality is better than±4% at the 2.5 overlap level, meets the superior specified in standard; The distribution quality of Synchronous Chipsealer can be increased by spray asphalt of different flow rang with nozzle of different diameter

为了加快同步碎石封层技术的推广，提高同步碎石封层设备的作业质量，本文对同步碎石封层设备作业质量的影响因素与控制方法、液压系统的动力学特性和沥青喷嘴的喷洒特性等关键技术进行了深入细致的研究：1研究了影响同步碎石封层作业质量的因素，提出了采用联合密度分布置信概率对同步碎石封层中沥青洒布量和碎石撒布量的系统偏差和标准差指标进行综合评价的方法，克服了传统评价方法只能对单一指标进行评价的缺陷；2采用数理统计的方法，研究了沥青泵的容积效率特性，修正了沥青泵容积效率公式，为沥青喷洒系统的匹配和沥青泵出口流量的精确控制提供了依据；采用数理方程推导与试验相结合的方法，研究了同步碎石封层设备液压系统的动力学特性，为从设计和控制的角度提高同步碎石封层设备液压系统的稳定性和效率奠定了理论基础；3运用AMESim软件对采用负载敏感控制和恒压控制的两种同步碎石封层设备液压系统进行仿真，结果表明：负载敏感控制的并联液压系统在多回路同时工作时，由于液压泵排量控制参考压力不稳定，容易引发液压系统振荡，恒压控制的并联液压系统是目前技术条件下比较理想的同步碎石封层设备工作装置驱动方案；该结论亦通过同步碎石封层设备装机试验得到了验证。4采用试验的方法对沥青喷嘴的喷洒特性进行了研究，结果表明：沥青洒布的横向精度并不是随着喷洒扇面重叠度的增加线性增加，其最高点通常出现在二个重叠度之间的"半重叠位置"，"2.5重叠"洒布时，沥青的横向洒布精度≤±4%，可以达到国家相关标准中的优级标准；同步碎石封层设备还可以根据不同洒布量情况下的流量需求，采用不同通径的喷嘴进行喷洒，提高沥青洒布精度。

What this paper finished mainly work as follows: Five-phase hybrid step motor driver system with fixed-chopping frequency and constant total current driving is fully described. Mathematical model of the system, included the current control circuit, power driving circuit and five-phase hybrid stepping motor is established. The steady modeling of the system is established and studied. Based on the steady modeling of the system, dynamic modeling of the system is studied and single step response characteristic is constructed with MATLAB/Simulink. The simulation results, which is certified by the theory analysis, coincide with the theory analysis.

本文主要完成的工作包括几个方面：对五相混合式步进电动机恒频斩波恒总流驱动系统进行了完整的描述；建立了包括电流控制电路、功率驱动电路以及五相混合式步进电动机在内的恒频斩波恒总流驱动系统的完整的数学模型；基于MATLAB/Simulink建立了恒频斩波恒总流驱动系统稳态仿真模型，并进行了仿真；在建立其稳态仿真模型的基础上，对动态模型进行研究，并借助于MATLAB/Simulink工具建立了恒频斩波恒总流驱动系统单步响应特性的仿真模型并对其单步响应特性进行了仿真研究，仿真结果与理论分析相符。

The Math object features a full complement of built-in mathematical constants and functions, such as E (Euler's constant), cos, and atan.

数学对象以一系列的数学常量和功能为特点，如E、cos、atan。

One approach, from mathematical point of view, is to translate the test into comparson of the constant a and proportion b of linear regression by using F test .

数学上该问题转化为对回归直线的常数 a和比例系数 b两组随机样本的 F检验。

ABSTRACT Aiming at problems of trans-vector controller in a vehicle-carried induction motor such as variable rotor and stator resistance following motor temperature, and their inductance varying with flux saturation degrees. Firstly, CSI and VSI are introduced, for CSI, it can hold the advantages both FOC and DTC using stator flux directional, PI parameter and simulation are also introduced. Secondly, equations of IM in the synchronous rotary frame and its static counterpart, as figuring in the saturation condition of magnetic field, are dealt in this paper and the simulation results are presented. Thereafter, the parameter designing of PI trans-vector controller is processed, which features the non-linear model. In practical realization, as neglecting the dynamical change of motor inductance, this paper employs online modification of inductance parameters, according to the flux saturation, then transforms the non-linear equations into linear ones, and so compacts the structure of controller. Thirdly, in view of the maximum torque output is extraordinary requisite when Electrical Vehicle start up, accelerate, and overtake, this paper issues the maximum torque when both inverter and battery capacity is corporeally definite. Fourthly, on-line differentiating and analyzing both rotor's time constants and its flux by using the expanding order reduction and discrete Kalman filter equation are fathomed, in order to realize high-performance trans-vector algorithm, and also the simulation results are presented. Fifthly, the close-loop regenerative brake system, when the EV's torque is set constant, is deduced; at the same time, unification of electric drive model and brake model is executed. Combined with maximum charge current demands, the mathematical model for online yielding torque as a demand.

本论文针对车载异步电机在矢量控制器所遇到的问题：定转子电阻随温度变化及随电机饱和程度变化的转子电感及定子电感而影响电机调速性能提出一套完整的解决方案：分析了电流型逆变器和电压型逆变器在实现矢量控制时控制器参数的计算，分析出对于电流型逆变器在采用定子磁场定向时，其性能同时具有矢量控制和直接转矩控制两者的优势，并对电压型逆变器在转子磁场定向下的模型进行了仿真研究；建立异步电机非线性模型，推导出考虑磁饱和时异步电机在同步旋转坐标系及静止坐标系下的方程，并做出了仿真结果，建立异步电机在非线性模型下的矢量控制调节器的PI参数设计，在实际应用中，若忽略电机电感的动态变化，可以根据当前的磁路饱和状态而在线修正电感参数，从而将非线性方程线性化，降低控制器的复杂度；考虑到电动汽车在起动和加速超车时需要电机有最大转矩输出，本文讨论在逆变器容量一定和电池供电能力有限的情况下电机最大转矩输出问题；推导了异步电机扩展降阶、离散卡尔曼滤波方程在线辨识转子时间常数和转子磁通，用于实现高性能的矢量控制算法，并给出了仿真结果；推导出了电动汽车恒转矩给定的闭环回馈制动系统，实现了电动控制模型和制动模型的统一，而且结合铅酸电池最大充电电流的要求，为制动转矩在线给定建立了数学模型；设计了基于双DSP系统的高性能矢量控制器软硬件框图，并以大量实验数据说明矢量控制在电动汽车应用的实际应用状况。

Current tuning is introduced, and the speed open-loop transfer function is established based on current closed-loop. A mathematical inequation about the speed open-loop transfer function is deduced, then the measured amplitude-frequency data is introduced in the inequation, thus the mathematic expressions about moment of inertia and mechanism time constant are obtained.

引入了电流校正环节，建立了基于电流闭环的速度开环传递函数，推导了关于该速度开环传递函数的数学不等式，再将实际测得的幅频特性代入此不等式中，得到了关于转动惯量和机械时间常数的数学表达式。

This paper discussed the mathematical model of speed control for keeping linear velocity of the welding torch with soldered dot on ellipse circumference constant.

主要讨论为保证焊枪相对于椭圆圆周上的焊点线速度恒定而进行的速度控制，以及保持焊枪始终在工件的焊接轨迹上而进行的位置控制的数学模型。

Something that has a magnitude and can be represented in mathematical expressions by a constant or a variable.

有一定大小，并可以用数学中的常数和变数表示的东西。

A mathematical expression consisting of the constant e raised to some power.

把常数升高到特定的幂的数学表达式。

And appears as a constant in many mathematical expressions.

圆'。''的周长与直径的比例，在许多数学式中作为常数出现

Although translator has turned from being a crystal ball by which the original culture can unrestrainedly penetrate to another crystal ball by which the target culture can freely traverse, the translator's personal embodiment, in the process of cognitive act, are still absent in translation studies. Translators are still subjects without body or simply disembodied subjects.

译者虽然由原语文化可以自由穿透的玻璃球变成了译语文化可以自由穿越的玻璃球，但译者认知过程中的个体体验在翻译研究中依然缺席，译者依然仅仅是一个没有躯体体验的主体。

Chillingly, he claimed our technology is 'not nearly as sophisticated' as theirs and "had they been hostile", he warned 'we would be been gone by now'.

令人毛骨悚然的，他声称我们的技术是'并不那么复杂，像他们一样，和"如果他们敌意"，他警告说，'我们将现在已经过去了。