16位高性价比产品冲击8位MCU市场

德州仪器(TI)推出MSP430微处理器(MCU)Value Line系列,以8位MCU的超低价格实现16位产品的性能以及超低功耗,充分满足8位产品市场不断提高的性能和效率要求.起价仅25美分的Value Line可确保8位产品的开发人员不再因价格问题而降低性能、电源效率或可扩展性.     

用样点加密和补零充位提高频谱分辨率

在地震数据处理中,频谱分析是不可缺少的重要环节。PE—3284机TRAFO模块是采用FFT算法进行频谱分析的。由于频谱的分辨率与被处理的时窗长度成正比,当时窗长度小于2000ms时,分辨率很低,不能用于实际生产。本文提出用样点加密和补零充位的方法提高频谱分辨率,效果明显,方法简单,对时窗长度大于75ms的谱分析,完全能满足实际处理需要。     

QFT template generation for time-delay plants based on zero-inclusion test

Plant template generation is the key step in applying quantitative feedback theory (QFT) to design robust control for uncertain systems. In this paper we propose a technique for generating plant templates for a class of linear systems with an uncertain time delay and affine parameter perturbations in coefficients. The main contribution lies in presenting a necessary and sufficient condition for the zero inclusion of the value set f(T,Q)={f(τ,q): τT[τ⁻,τ⁺], qQ∏_k=0^m−1[q_k⁻,q_k⁺]}, where f(τ,q)=g(q)+h(q)e^−jτω*, g(q) and h(q) are both complex-valued affine functions of the m-dimensional real vector q, and ω^* is a fixed frequency. Based on this condition, an efficient algorithm which involves, in the worst case, evaluation of m algebraic inequalities and solution of m2^m−1 one-variable quadratic equations, is developed for testing the zero inclusion of the value set f(T,Q). This zero-inclusion test algorithm allows one to utilize a pivoting procedure to generate the outer boundary of a plant template with a prescribed accuracy or resolution. The proposed template generation technique has a linear computational complexity in resolution and is, therefore, more efficient than the parameter gridding and interval methods. A numerical example illustrating the proposed technique and its computational superiority over the interval method is included.     

Characteristics for Leveraging Value Management Processes on Capital Facility Projects

A more competitive business environment requires that a variety of value management process (VMP) options be continuously introduced into the construction industry. Project stakeholders and managers are highly concerned about value maximization through implementation of one or more beneficial VMP options. The objective of this study is to identify the most leveraging project characteristic factors (PCFs) in need of VMP implementation. Furthermore, the levels of importance of each PCF in association with the optional VMPs are quantified to effectively assess the applicability of VMP implementation using the fuzzy-based analytic hierarchy process method. Four real-case validation tests provide robust research findings. The proposed project assessment tool is useful in evaluating individual projects in terms of whether the subject project is leveraged or has much to be improved by implementing the optional VMPs. The results of this study can facilitate a rigorous evaluation of a project and eventually help the decision-making process in selecting the most beneficial VMP options to maximize the optimum project value.     

Symmetry Breaking Constraints for Value Symmetries in Constraint Satisfaction

Constraint satisfaction problems (CSPs) sometimes contain both variable symmetries and value symmetries, causing adverse effects on CSP solvers based on tree search. As a remedy, symmetry breaking constraints are commonly used. While variable symmetry breaking constraints can be expressed easily and propagated efficiently using lexicographic ordering, value symmetry breaking constraints are often difficult to formulate. In this paper, we propose two methods of using symmetry breaking constraints to tackle value symmetries. First, we show theoretically when value symmetries in one CSP correspond to variable symmetries in another CSP of the same problem. We also show when variable symmetry breaking constraints in the two CSPs, combined using channeling constraints, are consistent. Such results allow us to tackle value symmetries efficiently using additional CSP variables and channeling constraints. Second, we introduce value precedence, a notion which can be used to break a common class of value symmetries, namely symmetries of indistinguishable values. While value precedence can be expressed using inefficient if-then constraints in existing CSP solvers, we propose efficient propagation algorithms for implementing global value precedence constraints. We also characterize several theoretical properties of the value precedence constraints. Extensive experiments are conducted to verify the feasibility and efficiency of the two proposals.     

Order Reduction Is Invalid for Singularly Perturbed Control Problems with a Vector Fast Variable

The order reduction method for singularly perturbed optimal control systems consists of employing the system obtained while setting the small parameter to zero. In many situations the differential-algebraic system thus obtained indeed provides an appropriate approximation to the singularly perturbed optimal control problem under consideration. In this paper we show, however, that the set of singularly perturbed optimal control systems for which the order reduction approach is invalid is dense (in the L ^∞ norm) in the class of systems which we consider. This is established under the assumption that the fast variable in the singularly perturbed system is not a scalar. Date received: June 8, 2001. Date revised: December 30, 2001.     

微机控制潜水电泵试验台优化设计的研究

本文在潜水电泵试验台系统分析的基础上,利用技术经济学的价值工程法建立了潜水电泵试验台优化判据和优化设计的数学模型。首次用数值求解的方法求得最佳仪表组合方案。为潜水电泵试验台的设计提供了理论依据。     

二次函数存在最优解(极小解)的充分必要条件

讨论了二次函数存在最优解(极小解)的充分必要条件,     

技术与经济相结合优选水泥厂设计方案——山东铝业水泥厂技术方案的确定

以山东铝业水泥厂技术改造为例，将技术与经济相结合，科学地选择技术方案。     

开关式PID的原理与应用

本文提出了开关式PID的控制律.并给出了给定值作大幅度变化下的算法以及用微机实现该算法的程序流程。