php做的网站 连接mysql数据库 效率问题

你可以把连接的方法写进类里，让它形成方法比如

class something {

global $db;

function web_db(){

$this-db = $this-database(); //把连接方法存如属性里

}

function database($server = 'localhost',$root = 'root',$pass = '****'){

......//这里写你的连接方法，及其关联表操作

}

...//其他方法

} //class end

在你的页面程序中这样写

require_once "web_common.class.php";//包进你的类文件

$mysql = new something;

在你需要数据查询或写入的时候只要调用 $mysql-db;就好了

如上你可以看出，无论你有多少客户请求数据库，而数据库只在载入页面时连接一次而已，调用 $mysql-db 只是请求程序，请求方法而已，没有请求数据库。第一，数据库连接查询只有一次；第二无形中也加快了页面的载入速度。

记住，你做网页不是给一个人两个人用的，而是很很很多个，为了保证数据库的正常使用，在多请求的情况下依然能很好工作，这是个很好的办法。

最后close是可写可不写的，因为当mysql没有请求时，它会自动关闭。

用英文解释正弦波谐振电路的电路组成和原理

我原来就想直接把网址弄下来，但是BD不让我发。说我的内容里有广告~~

这是我自己找的，里面有很多的公式，没办法粘过来，你自己琢磨琢磨，看看是什么公式

RLC circuit

An RLC circuit (also known as a resonant circuit, tuned circuit, or LCR circuit) is an electrical circuit consisting of a resistor (R), an inductor (L), and a capacitor (C), connected in series or in parallel. This configuration forms a harmonic oscillator.

Tuned circuits have many applications particularly for oscillating circuits and in radio and communication engineering. They can be used to select a certain narrow range of frequencies from the total spectrum of ambient radio waves. For example, AM/FM radios with ****og tuners typically use an RLC circuit to tune a radio frequency. Most commonly a variable capacitor is attached to the tuning knob, which allows you to change the value of C in the circuit and tune to stations on different frequencies.

An RLC circuit is called a second-order circuit as any voltage or current in the circuit can be described by a second-order differential equation for circuit ****ysis.

Configurations

Every RLC circuit consists of two components: a power source and resonator. There are two types of power sources – Thévenin and Norton. Likewise, there are two types of resonators – series LC and parallel LC. As a result, there are four configurations of RLC circuits:

Series LC with Thévenin power source

Series LC with Norton power source

Parallel LC with Thévenin power source

Parallel LC with Norton power source.

It is relatively easy to show that each of the two series configurations can be transformed into the other using elementary network transformations – specifically, by transforming the Thévenin power source to the equivalent Norton power source, or vice versa. Likewise, each of the two parallel configurations can be transformed into the other using the same network transformations. Finally, the Series/Thévenin and the Parallel/Norton configurations are dual circuits of one another. Likewise, the Series/Norton and the Parallel/Thévenin configurations are also dual circuits.

[edit] Similarities and differences between series and parallel circuits

The expressions for the bandwidth in the series and parallel configuration are inverses of each other. This is particularly useful for determining whether a series or parallel configuration is to be used for a particular circuit design. However, in circuit ****ysis, usually the reciprocal of the latter two variables is used to characterize the system instead. They are known as the resonant frequency and the Q factor respectively.

[edit] Fundamental parameters

There are two fundamental parameters that describe the behavior of RLC circuits: the resonant frequency and the attenuation (or, alternatively, the damping factor). In addition, other parameters derived from these first two are discussed below.

[edit] Resonant frequency

The undamped resonant frequency of an RLC circuit (in radians per second) is given by

In the more familiar unit hertz (or cycles per second), the resonant frequency becomes

Resonance occurs when the complex impedance ZLC of the LC resonator becomes zero:

Both of these impedances are functions of angular frequency ω:

Setting the magnitude of the impedance to be zero at ω = ω0 and using j2 = − 1:

[edit] Attenuation

The attenuation α is defined as

for the series RLC circuit, and

for the parallel RLC circuit.

[edit] Damping factor

The damping factor ζ is the ratio of the attenuation α to the resonant frequency ω0 :

for a series RLC circuit, and:

for a parallel RLC circuit.

It is sometimes more convenient to use the damping factor, which is dimensionless, instead of the attenuation factor, which has dimensions of radians per second, to ****yze the properties of a resonant circuit.

[edit] Minimizing the attenuation for oscillator circuits

For applications in oscillator circuits, it is generally desirable to make the attenuation (or equivalently, the damping factor) as **all as possible. In practice, this objective requires making the circuit's resistance R as **all as physically possible for a series circuit, or alternatively increasing R to as much as as possible for a parallel circuit. In either case, the RLC circuit becomes a good approximation to an ideal LC circuit.

Alternatively, for applications in bandpass filters, the value of the damping factor is chosen based on the desired bandwidth of the filter. For a wider bandwidth, a larger value of the damping factor is required (and vice versa). In practice, this requires adjusting the relative values of the resistor R and the inductor L in the circuit.

[edit] Derived parameters

The derived parameters include bandwidth, Q factor, and damped resonance frequency.

[edit] Bandwidth

The RLC circuit may be used as a bandpass or band-stop filter by replacing R with a receiving device with the same input resistance. In the Series case the bandwidth (in radians per second) is

Alternatively, the bandwidth in hertz is

The bandwidth is a measure of the width of the frequency response at the two half-power frequencies. As a result, this measure of bandwidth is sometimes called the full-width at half-power. Since electrical power is proportional to the square of the circuit voltage (or current), the frequency response will drop to at the half-power frequencies.

[edit] Damped resonance

The damped resonance frequency can be expressed in terms of the undamped resonance frequency and the damping factor. If the circuit is underdamped, meaning

or equivalently

then we can define the damped resonance as

In an oscillator circuit

.

or equivalently

.

As a result

.

See discussion of underdamping, overdamping, and critical damping, below.

[edit] Circuit ****ysis

[edit] Series RLC with Thévenin power source

In this circuit, the three components are all in series with the voltage source.

Series RLC Circuit notations:

v - the voltage of the power source (measured in volts V)

i - the current in the circuit (measured in amperes A)

R - the resistance of the resistor (measured in ohms = V/A);

L - the inductance of the inductor (measured in henrys = H = V·s/A)

C - the capacitance of the capacitor (measured in farads = F = C/V = A·s/V)

q - the charge across the capacitor (measured in coulombs C)

Given the parameters v, R, L, and C, the solution for the charge, q, can be found using Kirchhoff's voltage law. (KVL) gives

For a time-changing voltage v(t), this becomes

Using the relationship between charge and current:

The above expression can be expressed in terms of charge across the capacitor:

Dividing by L gives the following second order differential equation:

We now define two key parameters:

and

Substituting these parameters into the differential equation, we obtain:

or

[edit] Frequency domain

The series RLC can be ****yzed in the frequency domain using complex impedance relations. If the voltage source above produces a complex exponential wave form with complex amplitude V(s) and angular frequency s = σ + iω , KVL can be applied:

where I(s) is the complex current through all components. Solving for I(s):

And rearranging, we have at

[edit] Complex admittance

Next, we solve for the complex admittance Y(s):

Finally, we simplify using parameters α and ωo

Notice that this expression for Y(s) is the same as the one we found for the Zero State Response.

[edit] Poles and zeros

The zeros of Y(s) are those values of s such that Y(s) = 0:

and

The poles of Y(s) are those values of s such that . By the quadratic formula, we find

Notice that the poles of Y(s) are identical to the roots λ1 and λ2 of the characteristic polynomial.

[edit] Sinusoidal steady state

If we now let s = iω....

Taking the magnitude of the above equation:

Next, we find the magnitude of current as a function of ω

If we choose values where R = 1 ohm, C = 1 farad, L = 1 henry, and V = 1.0 volt, then the graph of magnitude of the current i (in amperes) as a function of ω (in radians per second) is:

Sinusoidal steady-state ****ysis

Note that there is a peak at imag(ω) = 1. This is known as the resonant frequency. Solving for this value, we find:

[edit] Parallel RLC circuit

Parallel RLC Circuit notations:

V - the voltage of the power source (measured in volts V)

I - the current in the circuit (measured in amperes A)

R - the resistance of the resistor (measured in ohms = V/A);

L - the inductance of the inductor (measured in henrys = H = V·s/A)

C - the capacitance of the capacitor (measured in farads = F = C/V = A·s/V)

The complex admittance of this circuit is given by adding up the admittances of the components:

The change from a series arrangement to a parallel arrangement has some very real consequences for the behaviour. This can be seen by plotting the magnitude of the current . For comparison with the earlier graph we choose values where R = 1 ohm, C = 1 farad, L = 1 henry, and V = 1.0 volt and ω in radians per second:

Sinusoidal steady-state ****ysis

There is a minimum in the frequency response at the resonant frequency .

A parallel RLC circuit is a example of a band-stop circuit response that can be used as a filter to block frequencies at the resonance frequency but allow others to pass.

在VC＋＋6．0中，总是出现一个叫error spawning c1.exe的错误，怎么回事呢？

楼上正解

我这里有基本错误的解决办法

以后一定会用到：

在创建项目时, 不使用MFC AppWizard向导, 如果没有设置好项目参数, 就会在编译时产生很多连接错误, 如error LNK2001错误, 典型的错误提示有:

libcmtd.lib(crt0.obj) : error LNK2001: unresolved external symbol _main

LIBCD.lib(wincrt0.obj) : error LNK2001: unresolved external symbol _WinMain@16

msvcrtd.lib(crtexew.obj) : error LNK2001: unresolved external symbol _WinMain@16

nafxcwd.lib(thrdcore.obj) : error LNK2001: unresolved external symbol __beginthreadex

nafxcwd.lib(thrdcore.obj) : error LNK2001: unresolved external symbol __endthreadex

下面介绍解决的方法:

1. Windows子系统设置错误, 提示:

libcmtd.lib(crt0.obj) : error LNK2001: unresolved external symbol _main

Windows项目要使用Windows子系统, 而不是Console, 可以这样设置:

[Project] -- [Settings] -- 选择"Link"属性页,

在Project Options中将/subsystem:console改成/subsystem:windows

2. Console子系统设置错误, 提示:

LIBCD.lib(wincrt0.obj) : error LNK2001: unresolved external symbol _WinMain@16

控制台项目要使用Console子系统, 而不是Windows, 设置:

[Project] -- [Settings] -- 选择"Link"属性页,

在Project Options中将/subsystem:windows改成/subsystem:console

3. 程序入口设置错误, 提示:

msvcrtd.lib(crtexew.obj) : error LNK2001: unresolved external symbol _WinMain@16

通常, MFC项目的程序入口函数是WinMain, 如果编译项目的Unicode版本, 程序入口必须改为wWinMainCRTStartup, 所以需要重新设置程序入口:

[Project] -- [Settings] -- 选择"C/C++"属性页,

在Category中选择Output,

再在Entry-point symbol中填入wWinMainCRTStartup, 即可

4. 线程运行时库设置错误, 提示:

nafxcwd.lib(thrdcore.obj) : error LNK2001: unresolved external symbol __beginthreadex

nafxcwd.lib(thrdcore.obj) : error LNK2001: unresolved external symbol __endthreadex

这是因为MFC要使用多线程时库, 需要更改设置:

[Project] -- [Settings] -- 选择"C/C++"属性页,

在Category中选择Code Generation,

再在Use run-time library中选择Debug Multithreaded或者multithreaded

其中,

Single-Threaded 单线程静态链接库(release版本)

Multithreaded 多线程静态链接库(release版本)

multithreaded DLL 多线程动态链接库(release版本)

Debug Single-Threaded 单线程静态链接库(debug版本)

Debug Multithreaded 多线程静态链接库(debug版本)

Debug Multithreaded DLL 多线程动态链接库(debug版本)

单线程: 不需要多线程调用时, 多用在DOS环境下

多线程: 可以并发运行

静态库: 直接将库与程序Link, 可以脱离MFC库运行

动态库: 需要相应的DLL动态库, 程序才能运行

release版本: 正式发布时使用

debug版本: 调试阶段使用

VC 6.0“Compiling... ,Error spawning cl.exe”错误解决

Posted on 2005-06-03 19:55 k_eckel 阅读(8862) 评论(100) 编辑 收藏

可能很多人在安装VC 6.0后有过点击“Compile”或者“Build”后被出现的“Compiling... ,Error spawning cl.exe”错误提示给郁闷过。很多人的选择是重装，实际上这个问题很多情况下是由于路径设置的问题引起的，“CL.exe”是VC使用真正的编译器（编译程序），其路径在“VC根目录\VC98\Bin”下面，你可以到相应的路径下找到这个应用程序。

因此问题可以按照以下方法解决：点击VC“TOOLS（工具）”—“Option（选择）”—“Directories（目录）”重新设置“Excutable Fils、Include Files、Library Files、Source Files”的路径。很多情况可能就一个盘符的不同（例如你的VC装在C，但是这些路径全部在D），改过来就OK了。

nafxcw.lib(appcore.obj) : error LNK2001: unresolved external symbol ___argv

解决方法：

在Preprocessor中定义_AFXDLL

如果它提示：

fatal error C1189: #error : Please use the /MD switch for _AFXDLL builds

就这样改：

C/C++-Code Generation-Multithread DLL （即实现/MD选项）

Visual C++ Error MessagesThis page contains a listing of "difficult to diagnose" error messages and possible fixes. I haven't taught a programming class that uses Visual C++ in several years so this list is probably out of date by now. It was valid for Microsoft Visual C++ version 6.0 service pack 3.

--------------------------------------------------------------------------------

C1001: INTERNAL COMPILER ERROR (compiler file 'msc1.cpp', line 1786) Please choose the Technical Support command on the Visual C++ Help menu, or open the Technical Support help file for more information

This error results from leaving off the parentheses immediately following the function name in a function header. To correct the error simply add () to the end of the function name.

--------------------------------------------------------------------------------

C1010: unexpected end of file while looking for precompiled header directive

If your project is an MFC AppWizard created project then this error results from not #including StdAfx.h as the first ＃i nclude statement (before any other ＃i ncludes, data declarations, or executable program code).

--------------------------------------------------------------------------------

C1083: Cannot open precompiled header file: 'Debug/Project-Name.pch': No such file or directory

This error results from a missing file - the compiled version of StdAfx.cpp. Visual C++ does a poor job of keeping track of this file and frequently "forgets" how to build it. This problem often occurs after restoring a saved workspace from diskette without the Debug directory. To fix the error select StdAfx.cpp from the workspace file list them choose Compile from the Build menu. If that doesn't work the go to Project - Settings, select the C/C++ tab, and click the radio button labeled Create Precompiled Headers.

--------------------------------------------------------------------------------

C2001: newline in constant

This error is usually caused by a string or character constant that is missing its closing ' or " symbol.

--------------------------------------------------------------------------------

C2065: 'data-member name' : undeclared identifier

If this error occurs in one of your member functions then it is generally the result of forgetting the class scope operator in front of the function name in your .cpp file.

--------------------------------------------------------------------------------

C2143: syntax error : missing ';' before 'PCH creation point'

Check each of the ＃i nclude files to ensure that the closing brace of each class declaration is followed by a semicolon.

--------------------------------------------------------------------------------

C2143: syntax error : missing ';' before '*'

If this error is followed by two C2501 errors then the problem is an undeclared class name within a pointer declaration.

For example, the declaration:

CClass *pObject;

will generate the above error message followed by a C2501 error message for 'CClass' and another C2501 message for 'pObject'. The problem is that the compiler isn't recognizing CClass as a valid class/type name. To correct the problem add a ＃i nclude of the file containing the declaration of CClass (e.g., ＃i nclude CClass.h)

--------------------------------------------------------------------------------

C2447: missing function header (old-style formal list?)

This error usually results from a missing { or use of a ; instead of a { following the parameter list of a function header.

--------------------------------------------------------------------------------

C2511: 'function-name' : overloaded member function not found in 'class-name'

This error results from a mi**atch in the parameter list of a member function declaration (.h file) and definition (.ccp file). Check the forward declaration of the function in the .h file and its definition in the .cpp file and ensure that the number of parameters and the type of each parameter match exactly.

--------------------------------------------------------------------------------

C2512: 'constructor-function-name' : no appropriate default constructor available

This error usually occurs when you implement the constructor function of a derived class and forget to include parameter passing to the base class constructor function. For example assume that CDerived is derived from CBase and that the CBase constructor function requires one parameter (e.g., int A). If you define the CDerived constructor function as:

CDerived::CDerived(int A, int B) { ... }

the compiler will issue the above error message on the line containing the function header of CDerived::CDerived() because you haven't provided instructions for routing the parameter A to CBase::CBase(). Because you didn't provide instructions the compiler assumes that CBase::CBase() requires no arguments and it complains because no version of CBase::CBase() has been defined that accepts zero arguments.

If you intended to provide a version of CBase::CBase() that requires no arguments then the error message indicates that you forgot to declare that function in your base class declaration (e.g., in CBase.h).

If CBase::CBase() does require one or more arguments then you must correct the problem by including explicit instructions for passing parameters from the derived class constructor function to the base class constructor function. The correction for the example above is:

CDerived::CDerived(int A, int B) : CBase(A) { ... }

--------------------------------------------------------------------------------

C2556: 'function-name' : overloaded functions only differ by return type

C2371: 'function-name' : redefinition; different basic types

These errors usually result from a mi**atch of function type between a .h and .cpp file. Check the forward declaration of the function in the .h file and its definition in the .cpp file and make the function return type identical in both files.

--------------------------------------------------------------------------------

C2601: 'function-name' : local function definitions are illegal

This error results from defining one function inside the body of another function. It usually means that you omitted one or more } symbols in the function just before the function named in the error message.

--------------------------------------------------------------------------------

C2653: 'Class-Name' : is not a class or namespace name

This error usually results from not having ＃i nclude "StdAfx.h" as the first ＃i nclude statement in your class.cpp file. It can also occur if your class definition is in a .h file and you forget to ＃i nclude that .h file in another file that refers to the class name.

--------------------------------------------------------------------------------

C2661: 'Class-Name::Function-Name' : no overloaded function takes n parameters

This error indicates a mi**atch between the parameters used in a function call (e.g., from main.cpp) and the declaration of the function. The function call is passing n parameters and there is no function declaration that uses that number of parameters.

--------------------------------------------------------------------------------

LNK1104: Cannot open file nafxcwd.lib

This error sometimes occurs when a project uses a class from the MFC but the project settings don't explicitly tell the link editor to look in the MFC libraries.

Go to Project -- Settings (Build -- Settings in Visual C++ 4.0). On the General tab check the box that says "Use MFC in a Shared DLL".

--------------------------------------------------------------------------------

LNK1168: cannot open Debug\Project-Name.exe for writing

This error occurs when the link editor attempts to write to a .exe file that is currently in use. The .exe file of an executing program is write protected until the program is terminated. Look at the status bar at the bottom of your screen and find the icon representing your executable application. Open the application and exit from it. Then select Build.

--------------------------------------------------------------------------------

LNK2001: unresolved external symbol __endthreadex

LNK2001: unresolved external symbol __beginthreadex

These errors result from using an MFC object or function without telling the link editor to search the MFC libraries.

Go to Project -- Settings (Build -- Settings in Visual C++ 4.0). On the General tab check the box that says "Use MFC in a Shared DLL".

--------------------------------------------------------------------------------

LNK2001: unresolved external symbol _main

Your project doesn't contain a function called main(). The error usually results from forgeting to add main.cpp to the project workspace.

--------------------------------------------------------------------------------

File.obj : error LNK2001: unresolved external symbol "public: void __thiscall Class1::Function1(Type)"

This a generic form of a LNK2001 error where File.obj can be any object file in your project and Class1::Function1(Type) can be any function in any class. Substitute the specific File, Class, Function, and Type in your message into the instructions below to diagnose and correct the problem.

An LNK2001 error means that the link editor is looking for a compiled function and can't find it. The call to the "missing function" is somewhere in File.cpp. Unfortunately, double-clicking on the error message won't take you to the point in File.cpp where the function is called but you can search for it with Find or Find In Files. The function the link editor can't find is a member of Class, its name is Function1, and its return type is Type.

There are two common reasons for a LNK2001 error:

The call in File.cpp doesn't match the function prototype in Class.h and/or the implementation in Class.cpp. The mi**atch may be in the function name, return type, or number and/or type of parameters. Correction strategies include:

Check that the function name is spelled the same (case sensitive) in all three files (File.cpp, Class.h, and Class.cpp).

Check that the function is actually declared and defined within Class - perhaps you defined it as a member of a different class or perhaps you tried to call the function (in File.cpp) using an object or object pointer of a different class.

Check that the number and type of parameters in the function implementation (in Class.cpp) matches the number and type of parameters declared in the function declaration in Class.h.

Check that the number and type of parameters in the function call (in File.cpp) matches the number and type of parameters declared in the function header in Class.cpp.

The function was never declared or was declared but never defined. To see if either is the case go to the ClassView window of the Workspace view. Click the + next to Class and find Function in the list of member functions.

If Function is NOT in the list then it was never declared or defined - add a declaration to the class declaraion in Class.h and implement the function in Class.cpp.

If Function is in the list then right click on it and select Go To Definition from the pop-up menu. If you get the error message Cannot find definition (implementation) of this function then the function was declared but never defined (implemented). Implement the function to Class.cpp.

--------------------------------------------------------------------------------

LNK2005: some-long-string-of-mostly-garbage already defined in name.lib(name.obj)

This error usually results from including a source code file multiple times. If you recognize any of the names in the message then it probably results from multiple inclusion of one of your own header files. Check to be sure that you've used #ifndef/#define/#endif properly your header files. If you don't recognize the name then it's probably multiple inclusion of a system file (e.g., afxwin.h). Make sure that you haven't explicitly included something in main.cpp that is already included in one of your own header files. Also check that you haven't ＃i ncluded a .cpp file where you should have ＃i ncluded a .h file.

英语句子求翻译

一个Texture（可能是结构的意思，具体要联系上下文）是一个二维的或者多维立体投影的图片和一系列的参数，它可以决定怎样从图片中抽取样品。

求助机械文献翻译第二篇

The estimated cutting force and the feedrate are the controlled output and the control input, respectively. Three control strategies are employed for the turning force control. 估计的切削力和进刀速度分别是受控的输出和控制输入。对于车削力的控制采用了三种控制策略。The first strategy is based on the PI controller which is designed from a nominal dynamic model.第一种策略基于比例积分（PI）控制器，它是由标称动态模型设计的。 The second strategy for the turning force control adopts a variable gain adaptive control using the estimated cutting force. 第二种用于车削力控制的策略采用一种可变增益自适应控制，它是利用估计的切削力。In this case the estimated force signal is considered as the true value and used for identifying the model parameters. 在这种情况下，估计的切削力信号被看作是真实的值，并被用于鉴别模型的参数。The adaptive control with constraint approach is used to improve the stability and the performance. 有限制的自适应控制（ACC）法可用于改善稳定性和性能。

A fuzzy logic controller (FZC) is designed for the last control strategy because the dynamic relation between the cutting force and the feedrate is too complex to be described in a nominal model. （我们）设计了一台模糊逻辑控制器（FZC）用于第三种控制策略，因为切削力和进刀速度之间的动态关系太复杂了，以致无法用通常的模型加以描述。The fuzzy logic rule is designed based on a series of the cutting tests and is formed into the standard PI fuzzy control.模糊逻辑的规则根据一系列切削实验设计，并被形成为标准的PI模糊控制。 All three control strategies as well as the synthesized cutting force monitor are constructed into a computer integrated CNC lathe. 所有这三种控制策略以及合成的切削力监控器都被构建到一台集成计算机的CNC车床上。For each control strategy, the control performance is compared between using the measured cutting force and using the estimated cutting force signals.对于每一种控制策略来说，都在两种情况下进行了对比，一种是采用了实测的切削力，另一种是采用的估计切削力信号。3.CUTTING FORCE MONITORING

3. 切削力监控

On-line and real-time information of the cutting force signal is the key factor for the turning force control. 切削力信号的在线信息和实时信息是车削力控制的关键因素。A cutting force monitoring system based on the AC spindle drive was presented before by the authors [4]. 作者以前已介绍过一种基于AC（交流）主轴传动的切削力监控系统【4】。They derived a dynamic model of the AC spindle drive and estimated the cutting force on-line using the measured power signal. 它们能在线利用实测的功率信号，导出AC主轴传动的动态模型和估计的切削力。Even if their estimation results at the steady state coincide with the measured signals within 3% error, the estimated force at the transient state showed a time lag of about 0.3 second. 即使它们在稳态下的估计结果与实测信号的一致性在3％的误差以内，但在瞬态时的估计切削力呈现约0.3秒的时间滞后。The time lag in sensing the controlled variable is the serious limitation for the control performance. 在传感受控变量中的时滞对控制性能是严重的限制。It turns out that the time lag is mainly due to the time delay of the measured output power signal, which, in turn, results in the time delay in the output torque of the AC motor because the motor torque is calculated simply by dividing the output power by the motor speed. 其结果是，时滞主要是由于实测输出功率信号的时间延迟引起的，它反过来导致AC电机输出转矩的时间延迟，因为电机转矩是将输出功率除以电机速度来计算的。

In this section, a new synthesized cutting force monitoring method is proposed to improve the transient estimation performance. 在本小节中，提出了一种新的合成的切削力监控方法，以改善瞬态估计性能。Because the main reason for the time lag is the insufficient sensing of the motor output power, another method to quickly obtain the motor torque is pursued using the AC motor characteristics. 因为时滞的主要原因是对电机输出功率传感的不充分，所以（我们）寻求另一种利用AC电机特性迅速获得电机转矩的方法。

Calculation Of The Motor Output Torque

电机输出转矩的计算

The output torque of the AC induction motor is activated due to the interaction between the stators's rotating magnetic field and the rotor's inducted currents and can be expressed in terms of the rotor input power and the synchronous speed. AC感应电机的输出转矩是由于定子的旋转磁场和转子的感生电流之间相互作用而引起的，而且可以用转子输入功率和同步转速来表达。where w, is the synchronous speed of the AC motor. The rotor input power is the difference between the electrical input power and the power losses in the stator windings.式中，W为AC电机的同步转速。转子输入功率是输入电功率和定子绕组中功率损耗之差值。

问题补充：For the delta-connected balanced load, the phase voltage is equal to the line voltage but the line current should be divided by ,13 to obtain the phase current.对于三角形连接的平衡负荷来说，相位电压等于线路电压，但线路电流应除以13才能得到相位电流。 In general, the input power of the AC motor can be obtained in terms of the root-mean-square values of the phase voltage and the phase current.一般来说，AC电机的输入功率可以用相位电压和相位电流的均方根值得到。It is assumed that the spindle motor rotates at the constant speed in turning process and the slip ratio is close to zero except at the moment when the cutting starts. 我们假设，主轴电机在车削过程中以恒定的转速旋转，除了在切削开始的瞬间，滑移率接近于零。Thus the output torque of Eq (l) can be approximated as().where wM is the motor speed. When the cutting starts or when the calculated electric power in Eq (2) increases abruptly, the slip ratio should be taken care of in Eq (1) instead of Eq.因此，式（1）的输出转矩可以近似为（……）.式中，mW是电机转速。当切削开始时，或者式（2）中计算的电功率突然增加时，式（1）中而不是式（×）

中的滑移率应予以注意。