强化DataGrid控件功能

DataGrid是数据库应用系统中使用最多的控件,本文对.NET的Windows窗体DataGrid控件,通过自定义类的设计,使之具有查找、筛选、排序、显示或隐藏列控制、读写列控制以及同步数据内容导出的功能,从而实现了对DataGrid的灵活控制.     

基于Delphi的网页源码保护功能的实现

在开发一个网页设计课程考试软件的过程中,发现仅用文字描述题目要求难以表述清楚,应该提供一个网页样例,要求只能看到网页效果而无法看到网页源码。介绍了内存中载入网页的方法,通过ActiveX技术将其应用于HTML网页,实现了HTML网页源码的隐藏,由于网页源码隐藏在ActiveX控件内,网页显示由控件完成,该方法具有较高的安全性。     

在TCP/IP协议中实现远程文件的传输

TCP/IP是Internet的基本协议。远程文件传输是以TCP/IP协议为基础,采用Delphi控件,将TCP/IP通信函数封装在ActiveX控件中,通过对ActiveX控件提供的对外接口的调用,隐藏了TCP/IP的实际实现过程,直接实现文件传输。程序采用客户机/服务器体系,服务器侦听连接请求,客户机发起请求,客户机与服务器合作实现文件的双向传输。     

GridView中显示/隐藏列及多重表头的实现

阐述了在ASP.NET的GridView控件中,显示/隐藏数据列以及设置多重表头的方法,给出的代码已在Vistual Studio+SQL Server开发环境中验证通过.     

在VC++中设计并实现历史趋势浏览控件

历史趋势控件主要完成对传送来的历史数据的显示及必要的设置，包括准确绘制趋势图；调整趋势图浏览的时间范围；设定按值显示或按比例显示模式；通过鼠标点击获取某时刻对应的数值；能够显示或隐藏数据线等操作。     

W83627HF的Watchdog ActiveX控件设计

介绍了一种ActiveX控件的详细开发方法,该控件实现对工业主板上常用SuperI/O芯片W83627内Watchdog的编程.控件以嵌入式工控机为核心,采用单元积木式结构,利用VC编程.具有智能化,可靠性、通用性好和操作简便等优点.控件为应用者提供一组简单的Watchdog的编程接口,隐藏各种对设备编程的细节,尤其是避免了应用程序在window2000/XP系统中进行I/O操作的难题.实践证明该控件可以广泛应用于计算机控制系统.     

利用控件隐藏方法实现数据库的自动加密解密

本文就典型数据库应用程序中后台数据库的加密解密问题,提供了一种简便易行的解决办法─控件隐藏方法。     

C#环境下动态侧边栏的实现

利用C#开发环境,在WinForm窗体中实现动态侧边栏。通过鼠标悬停于ToolStripButton控件触发侧边栏展开,使用后台线程技术实现侧边栏展开的动态过程,判断鼠标移出侧边栏实现侧边栏的隐藏,也可以锁定侧边栏停靠软件左侧。     

自动扩展大小的TEdit

TEdit控件常常被用来输入文本数据。如果输入的内容太长,就会有一部分被隐藏起来。下面,我们来实现一个随着输入内容增加而自动变长的TEdit控件。把以下代码保存为ExpandingEdit.pas,在Delphi     

VB5.0中的新控件MSFlexGrid的使用方法

VB5中新添了许多ActiveX控件,其中一个功能强大的控件就是MSFlexGrid控件。MSFlexGrid控件网格中提供了显示数据的高级功能。它与DBGrid控件类似,但不像DBGrid那样允许用户编辑被绑定或包含在控件中的数据,它只是提供了一个强大的显示数据的能力。当然,如果想改变其中的数据,也可以通过编程来实现。     

Robust and adaptive control: fidelity or an open relationship?

Robust and adaptive control are essentially meant to solve the same control problem. Given an uncertain LTI model set with the assumption that the controlled plant slowly drifts or occasionally jumps in the allowed model set, find a controller that satisfies the given servo and disturbance rejection specifications. Specifications on the transient response to a sudden plant change or “plant jump” are easily incorporated into the robust control problem, and if a solution is found, the robust control system does indeed exhibit satisfactory transients to plant jumps. The reason to use adaptive control is its ability, when the plant does not jump, to maintain the given specifications with a lower-gain control action (or to achieve tighter specifications), and also to solve the control problem for a larger uncertainty set than a robust controller. Certainly equivalence-based adaptive controllers, however, often exhibit insufficient robustness and unsatisfactory transients to plant jumps. It is therefore suggested in this paper that adaptive control always be built on top of a robust controller in order to marry the advantages of robust and adaptive control. The concept is called adaptive robust control. It may be compared with gain scheduling, two-time scale adaptive control, intermittent adaptive control, repeated auto-tuning, or switched adaptive control, with the important difference that the control is switched between robust controllers that are based on plant uncertainty sets that take into account not only the currently estimated plant model set but also the possible jumps and drifts that may occur until the earliest next time the controller can be updated.     

Pilot ability to anticipate the consequences of flight actions as a function of expertise

The study offers insights into pilot ability to anticipate consequences of actions and how this ability changes with experience. Novice and expert pilots completed trials in which 3 screens depicted a control movement (or control movements), a cockpit flight situation, or a change in flight situation. Changes depicted in the 3rd screen of each trial were consistent, inconsistent with the mental model of the effect of the control movement or movements, or inconsistent with the application of the control movement(s) to the current flight situation. Pilots indicated whether the depicted change was inconsistent or consistent with their expectations, and accuracy of consistency judgments was greater for mental-model than for situation-model inconsistent statements. Experts are more accurate than novices, particularly for trials that involve multiple, meaningfully related control movements. Expert ability to organize information into meaningful units appears to facilitate future flight state projections, and projection failures appear to result from situation- rather than mental-model failures. Actual or potential applications of this research include analysis of flight situation awareness and flight performance errors.     

Translating user control availability into perception: the moderating role of prior experience

On a basic level, perception of user control over media content should be partially a function of control option availability. At the same time, prior user experience with control options should interact with control availability to produce joint effects on control perception. To assess these ideas, we present experimental data from 101 University students in the United States. Participants engaged a documentary in one of three ways: by simply watching the documentary, by watching the documentary with the option of using typical VCR-type controls (such as fast-forward or reverse), or by watching and having available both VCR-type controls and scene sequencing control. Data support our hypotheses. While there was a generally positive relationship between exposure to user control options and user control perception across all participants, those participants with relatively less prior experience with Internet-based applications demonstrated a somewhat different relationship between control availability and control perception.     

Data flow oriented control law design with the graphical language HOSTESS

HOSTESS is a workstation based specification and design tool for control laws in cyclic systems with fixed scheduling. The tool has been successfully applied to electronic flight control (fly by wire) and minor critical systems as centre of gravity control or a variety of development simulator modules. HOSTESS is a graphical data flow language with a restricted set of basic modules, simple control structures and extensive consistency checking avoiding coding errors, dead code or initialization problems. A special version with a reduced set of functions is compatible with tools used by suppliers or project partners.     

Lyapunov stability analysis of second-order sliding-mode control and its application to chattering reduction design

This paper proposes a new sliding mode control design with reduced control chattering. The proposed new design inherits the design concept from dynamic sliding mode control, in which the first-order time derivative of the control input is treated as the control variable for a chattering control design. Previous dynamic sliding mode designs require an extra uncertainty observer or uncertainty estimator to construct the sliding surface. This paper is able to waive such observer or estimator.     

Model-free learning control of neutralization processes using reinforcement learning

The pH process dynamic often exhibits severe nonlinear and time-varying behavior and therefore cannot be adequately controlled with a conventional PI control. This article discusses an alternative approach to pH process control using model-free learning control (MFLC), which is based on reinforcement learning algorithms. The MFLC control technique is proposed because this algorithm gives a general solution for acid–base systems, yet is simple enough to be implemented in existing control hardware without a model. Reinforcement learning is selected because it is a learning technique based on interaction with a dynamic system or process for which a goal-seeking control task must be performed. This “on-the-fly” learning is suitable for time varying or nonlinear processes for which the development of a model is too costly, time consuming or even not feasible. Results obtained in a laboratory plant show that MFLC gives good performance for pH process control. Also, control actions generated by MFLC are much smoother than conventional PID controller.     

基于编码控制机制的混杂系统半全局实用镇定

混杂系统的鲁棒镇定是复杂控制系统领域的重要研究课题之一.提出了一种编码机制下的混杂控制策略,它能有效地克服传统连续反馈控制或不连续反馈控制在处理局部鲁棒镇定平衡点或不变集问题中的局限性,获得更好的控制效果.首先针对编码状态反馈,构建了一般的混杂系统模型来描述编码状态反馈作用下非线性系统的闭环系统模型.然后,基于逆Lyapunov定理开展了非线性系统的混杂控制鲁棒性分析,提出了闭环混杂系统的半全局实用渐近稳定性判据.最后,结合一个经典控制问题来说明所提出控制策略的优越性.     

Tutorial review on repetitive control with anti-windup mechanisms

In many control system applications, tracking a periodic reference signal or rejecting a disturbance signal with a limited frequency band is a necessary task. Repetitive control systems are designed to perform such tasks. Because the repetitive control systems by nature have introduced unstable controller structures, control signal amplitude constraints commonly encountered in control system applications need to be considered with special care. Otherwise, the repetitive control system could become unstable when the control signals became saturated. Using the same framework of Model Predictive Control (MPC), but without the cost of online optimization that usually occurs in the MPC algorithms, this paper shows the design and implementation procedures of repetitive control of multi-input and multi-output systems with anti-windup mechanisms. Furthermore, by using Fourier analysis of a reference signal or a disturbance signal, the structure of a repetitive control system is determined. Simple and complex simulation examples are used to illustrate the procedures of design and implementation.     

Experimental comparison and application of various parameter-adaptive control algorithms

Various recursive parameter estimation algorithms and controller design procedures can be combined to build up parameter-adaptive control algorithms. Two parameter estimation methods and six control algorithms have been selected, taking into account good convergence properties and small computational expense and regarding the conditions for closed-loop identification. The resulting 12 parameter-adaptive control algorithms are compared and tested with a process computer in on-line operation with analog simulated stable and unstable processes for stochastic disturbances and step changes of the reference signal. The results are very promising. In many cases a good control performance is achieved. As a priori knowledge only the sampling time, the process model order and time delay and in some cases a weighting factor for the process input signal are required. Some parameter-adaptive control algorithms with good properties are applied to digital adaptive control of an air heater. Conclusions are given for the selection of parameter-adaptive control algorithms, depending on the type of process and its disturbances.The adaptive control algorithms may be applied for adaptive control of constant and time variant, linear and weakly non-linear stable and unstable processes with process computers or micro computers or for self-tuning of control algorithms or tuning of conventional analog PID controllers, if external disturbances act on the loop.     

An architecture for adaptive fuzzy control in industrial environments

The paper presents an architecture for adaptive fuzzy control of industrial systems. Both conventional and adaptive fuzzy control can be designed. The control methodology can integrate a priori knowledge about the control and/or about the plant, with on-line control adaptation mechanisms to cope with time-varying and/or uncertain plant parameters. The paper presents the fuzzy control software architecture that can be integrated in industrial processing and communication structures. It includes four distinct modules: a mathematical fuzzy library, a graphical user interface (GUI), fuzzy controller, and industrial communication. Three types of adaptive fuzzy control methods have been studied, and compared: (1) direct adaptive, (2) indirect adaptive, and (3) combined direct/indirect adaptive. An experimental benchmark composed of two mechanically coupled electrical DC motors has been employed to study the performance of the presented control architectures. The first motor acts as an actuator, while the second motor is used to generate nonlinearities and/or time-varying load. Results indicate that all tested controllers have good performance in overcoming changes of DC motor load.