Simultaneous Removal of Phenol and Nitrate in an Anaerobic Bioreactor

Phenol and nitrate are two major pollutants simultaneously occurring in several industrial wastewaters. In this study, a 110-day gradual enrichment of an anaerobic culture has been carried out at 25°C in an anaerobic bioreactor for continuously treating a synthetic wastewater containing 600?mg/L phenol and 430?mg/L?NO3?–N. The results showed that the enriched culture can utilize phenol as a sole electron donor and nitrate as a sole electron acceptor. At the end of the enrichment (on Day 110), 93.3% of phenol and 98.0% of NO3?–N were simultaneously removed at a hydraulic retention time of 20.25?h in the anaerobic bioreactor. The removal of 1?g?NO3?–N required about 3.19?g chemical oxygen demand as the electron donor. Batch tests further revealed that cresol, nitrophenol, and monochlorinated phenol (MCP) could exert detrimental influences on the treatment abilities of the enriched culture. However, the inhibitory effects of cresol were impermanent, as compared to those of nitrophenol and MCP. In order to operate the anaerobic bioreactor steadily, high concentrations of cresol should be diluted before being fed while the existence of nitrophenol and MCP in the bioreactor should be avoided.     

Large-Eddy Simulation of High Reynolds Number Turbulent Flow Past a Square Cylinder

Flow past a square cylinder at a Reynolds number of 21,400 has been studied numerically using the large-eddy simulation technique. A dynamic subgrid-scale stress model has been used for the small scales of turbulence. The time- and span-averaged axial and transverse velocities in the downstream of the cylinder are in good agreement with the experimental results. The distribution of turbulent normal and shear stresses is also well predicted. The coherent and incoherent components of turbulent fluctuations at some specified phases have been separated and their relative magnitudes downstream of the cylinder have been compared. The comparison shows more coherence in the near wake than the far wake, while the coherent and incoherent components are of comparable magnitude in the far wake. The far wake shows irregular phase-averaged structures.     

基于有限元方法的双定子永磁同步发电机齿槽转矩研究

永磁电机不通电时永磁体与有槽电枢铁心之间相互作用,产生齿槽转矩,引起永磁电机低速起动困难。为了有效地削弱双定子低速稀土永磁同步发电机齿槽转矩,在目前国内外永磁电机齿槽转矩研究的基础上,建立了双定子低速稀土永磁同步发电机齿槽转矩的解析表达式,针对表达式中影响齿槽转矩大小的因素,利用有限元方法进行了仿真分析,得到了影响齿槽转矩大小的变化规律,为发电机最优设计提供重要依据。     

A singleton failures semantics for Communicating Sequential Processes

This paper defines a new denotational semantics for the language of Communicating Sequential Processes (CSP). The semantics lies between the existing traces and failures models of CSP, providing a treatment of non-determinism in terms of singleton failures. Although the semantics does not represent a congruence upon the full language, it is adequate for sequential tests of non-deterministic processes. This semantics corresponds exactly to a commonly used notion of data refinement in Z and Object-Z: an abstract data type is refined when the corresponding process is refined in terms of singleton failures. The semantics is used to explore the relationship between data refinement and process refinement, and to derive a rule for data refinement that is both sound and complete. Received October 2001 Revised September 2002, February 2003, June 2004 and October 2005 Accepted November 2005 by I. J. Hayes     

Some Kind of Analogtivity: anti-simulation through design

This paper discusses and explores issues surrounding current approaches to the design of technological products and offers two critical design proposals for presentation and debate. Primarily driven by contemporary theoretical writings and thoughts on the subject of ‘technology’ and ‘simulation’, currently being offered by leading thinkers on these subjects and expressed as ‘technological objects’; they are the result of a critical investigation into the emerging design issues surrounding ‘interaction’ and ‘transparency’. By using ‘popular’ language of product design as a vehicle, they exist as ‘cultural offerings’ exploring an alternative future for technological products not necessarily governed by science and economics.     

Flash脚本在多媒体课件开发中的应用

本文通过一个游标卡尺仿真实验,介绍了FLASH动作脚本在多媒体课件制作中的应用,引深出在多媒体课件制作领域,Flash已成为教师和教育工作者首选的软件。FLASH具备完善的面向对象的程序设计,能够实现多媒体课件各种类型的交互功能,FLASH课件引入课堂以后,改变了课堂教学形式的单一、直观性差的缺憾,构建出一种平等的、互动式的课堂教学模式,成为教师教学和学生学习的有力助手。     

Lyapunov controller design for transverse vibration of a cable-linked transporter system

Modeling and Lyapunov controller design for transverse vibration of a flexible cable transporter system with arbitrarily varying lengths are presented using Hamilton's principle and Lyapunov theory. The axial velocity of the system is assumed to be unknown in the model. This is different from existing literature where the axial velocity is assumed either to be constant or prescribed. The governing equations include two coupled non-linear Partial Differential Equations (PDEs) and boundary conditions. The interactions between the cables and the slider, pulleys, and motors are included in the model. Numerical solution of the derived governing equations is obtained using Galerkin's method. Based on the Lyapunov theory, we propose two boundary controllers and one domain point-wise controller, which suppress the transverse vibration of the cables effectively while assuring the attainment of the slider goal. The proposed controllers dissipate the vibration energy and guarantee the stability of the closed-loop system in Lyapunov sense. Simulation results demonstrate the effectiveness of the proposed controllers.A short version of this paper was presented in 2004 ASME International Mechanical Engineering Conference and Exposition, Anaheim CA, November 14-19, 2004.     

神经网络技术在直接转矩控制系统中的应用

在传统直接转矩控制系统基础上，采用BP网络设计了状态选择器，并通过BP算法进行训练，对实际控制系统进行了仿真，结果证明了方案的可行性。     

The data-based mechanistic approach to the modelling, forecasting and control of environmental systems

The paper presents a unified approach to the modelling, forecasting and control of natural and man-made environmental systems. The modelling approach exploits the author’s Data-Based Mechanistic (DBM) modelling philosophy, combined with powerful methods of recursive statistical estimation. These provide the basis for two major stages of model building: first, the critical evaluation of the over-parametrized simulation models that are currently the most common vehicle used in environmental planning and management studies; and second, the adaptive, data-based estimation of parsimonious, ‘top-down’ models that can be used for adaptive forecasting and data assimilation, as well as operational control and management system design. The associated control system design methodology is based on the Non-Minimal State Space (NMSS) approach to the design of Proportional-Integral-Plus (PIP) control systems, based on the DBM models obtained at the previous modelling stage. The paper includes a case study concerned with the modelling and control of globally averaged levels of CO₂ in the atmosphere.