Condition Assessment of Buried Pipes Using Hierarchical Evidential Reasoning Model

Effective inspection and monitoring practices for the condition assessment of pipes ensure better decision(s) for repair or replacement before they fail. Pipe deterioration is a physical manifestation of the aging process in which many factors can contribute to structural failure. Various technologies/ techniques have been developed during the last few years to inspect/monitor piping systems, but how to intelligently interpret the collected data remains a challenge. In this paper, a new approach based on hierarchical evidential reasoning is proposed. This approach uses Dempster–Shafer (D-S) theory to make inferences for condition assessment of buried pipes. A hierarchical evidential reasoning model can help combine different distress indicators (bodies of evidence) at different hierarchical levels using D-S rule of combination. The proposed hierarchical evidential reasoning method is demonstrated with an example of condition assessment for a large diameter pipe. Information from multiple sources is fused to obtain a more reliable assessment of pipe deterioration.     

Use of Supervisory Control and Data Acquisition for Damage Location of Water Delivery Systems

Urban water delivery systems can be damaged by earthquakes or severely cold weather. In either case, the damage cannot easily be detected and located, especially immediately after the event. In recent years, real-time damage estimation and diagnosis of buried pipelines attracted much attention of researchers focusing on establishing the relationship between damage ratio (breaks per unit length of pipe) and ground motion, taking the soil condition into consideration. Due to the uncertainty and complexity of the parameters that affect the pipe damage mechanism, it is not easy to estimate the degree of physical damage only with a few numbers of parameters. As an alternative, this paper develops a methodology to detect and locate the damage in a water delivery system by monitoring water pressure on-line at some selected positions in the water delivery systems. For the purpose of on-line monitoring, emerging supervisory control and data acquisition technology can be well used. A neural network-based inverse analysis method is constructed for detecting the extent and location of damage based on the variation of water pressure. The neural network is trained by using analytically simulated data from the water delivery system with one location of damage, and validated by using a set of data that have never been used in the training. It is found that the method provides a quick, effective, and practical way in which the damage sustained by a water delivery system can be detected and located.     

Wavelet Network for Semi-Active Control

This paper proposes a wavelet neurocontroller capable of self-adaptation and self-organization for uncertain systems controlled with semiactive devices that are ideal candidates for control of large-scale civil structures. A condition on the sliding surface for cantilever-like structures is defined. The issue of applicability of the control solution to large-scale civil structures is made the central theme throughout the text, as this topic has not been extensively discussed in the literature. Stability and convergence of the proposed neurocontroller are assessed through various numerical simulations for harmonic, earthquake, and wind excitations. The simulations consist of semiactive dampers installed as a replacement for the current viscous damping system in an existing structure. The controller uses only localized measurements. Results show that the controller is stable for both active and semiactive control using limited measurements and that it is capable of outperforming passive control strategies for earthquake and wind loads. In the case of wind loads, the neurocontroller is found to also outperform a linear quadratic regulator (LQR) controller designed using full knowledge of the states and system dynamics.     

Autopilot for Reconfigurable Flight Control System

The main factor in design and operation of aircraft is safety of an airplane. The “safety culture” developed in aeronautics results in detailed regulations and certification procedures in all phases of aircraft design and operation. But despite that, aircraft safety depends on several unpredictable factors, such as the hostile actions both inside and outside of the aircraft. When failures occur during the flight, the most important actions are aimed at maintaining the aircraft controllability. The aircraft control system should be fault tolerant and ensure aircraft controllability in the event of the failure of a part of the flight control system. In this paper the influence of control surface failures on autopilot operation has been investigated. The autopilot is designed for business jet airplanes and fulfills the main functions of the real autopilot system in longitudinal and lateral directions. The autopilot structure allows implementation of various methods of reconfiguration for aircraft protection.     

Shaping Indirect Flight Control System Properties for General Aviation Aircraft

This paper describes calculations and computer simulations concerning handling qualities of general aviation aircraft equipped with an indirect (fly-by-wire) control system. The main idea of this proposal is shaping small aircraft dynamic characteristics in a way that enables all general aviation aircraft to exhibit similar user-friendly properties from the pilot’s point of view. The natural solution of this problem is modifying aircraft dynamic properties to comply with the “ideal model” of a safe and easily controllable airplane. We can improve the handling qualities of an aircraft using the indirect flight control system. In this paper, the model following method was used for controller synthesis, with the purpose of obtaining qualitatively new handling properties and simplifying the control system for pilots with limited professional training. However, a control system designer has to assume responsibility for proper functioning of complex flight control systems. The properties of the optimal controller were calculated applying the indirect (implicit) model following method. In particular, the modified version based on the computer simulations was used. Model following method allows shaping properties of the flight control systems that satisfactorily approximate those of the desired model of controlled aircraft. In this way, the expected handling qualities can be reached.     

New Structure for an Aerodynamic Fin Control System for Tail Fin-Controlled STT Missiles

This paper presents a new design method for an aerodynamic fin-control system for tail-fin controlled skid to turn (STT) missiles. The performance of the actuation system plays a decisive role in determining the performance of the flight control system for a highly maneuverable missile. To control the missiles by aerodynamics, control surfaces, sometimes called fins, are used. Deflection angles of these fins are the control variables of aerodynamics, but aerodynamicists prefer to use analytic variables called aileron, elevator, and rudder instead of these physical variables because these three analytic variables dominantly influence the roll, pitch, and yaw motion of the missile, respectively; and each can be considered a linear combination of four fin deflection angles. On that basis, roll, pitch, and yaw autopilots for controlling the attitudes or lateral acceleration of the missile are designed, and aileron, elevator, and rudder commands, respectively, are generated as consequence outputs of each autopilot. In the existing fin-actuation control scheme for the typical tail-fin controlled cruciform missiles, these outputs are distributed to four fin defection commands. After that, the four fins are actuated by fin controllers so that their deflections follow the commands. This paper shows that such control schemes can cause a significant deterioration in flight control system performance when fin-actuators have certain physical constraints such as slew rate, voltage, or current limit, or have an uncertainty of actuator dynamics, and proposes a new control scheme that alleviates such problems. This scheme can be widely applied to various fin-actuation control systems. But in this paper, for convenience, a tail-fin controlled cruciform missile is used as the example, and the proposed control scheme is shown to give better performance than the existing one.     

Prediction Models for Annual Break Rates of Water Mains

Annual break rates are often used by municipalities as one of the most important criteria in rating the condition of water mains. This paper presents the development of deterioration models that predict the annual break rates of water mains considering pipe material, diameter, age, and length. The data used in this paper are collected from a Canadian municipality that has a large water distribution network. The collected data cover 15-year pipe break records of 432?km of water mains. Five multiple regression models are developed, which show robust statistical analysis. Twenty percent of break data were randomly selected for validation in which the developed models demonstrate satisfactory results. The research presented in this paper is expected to be useful to academics and practitioners (municipal engineers, consultants, and contractors) in analyzing deterioration trends of water mains.     

Comparison of Statistical Deterioration Models for Water Distribution Networks

The use of water main break history as a proxy for condition has become common practice because of the high costs associated with direct assessments. Statistical deterioration models predict future water main breaks on the basis of historical patterns. Many municipalities are beginning to understand the value of utilizing water pipe break histories to manage their noncritical distribution networks via deterioration models. This paper presents a generic IDEF0 process model for developing water main deterioration models. Two common statistical deterioration models for water pipes are compared: rate-of-failure models (ROF) and transition-state (TS) models. ROF models extrapolate the breakage rate for a particular cohort of pipes and do not differentiate between the times between successive failures. On the other hand, transition-state models attempt to model the time between successive failures for pipes. This paper presents a comparison and analysis of ROF models and transition-state models by using a single data set for cast- and ductile-iron pipes in the City of Hamilton, Ontario, Canada. The paper compares the models’ ability to support breakage forecasting, long-term strategic planning, and short-term tactical planning. Best practices for pipe segmentation in support of water main deterioration models are presented.     

Linear Quadratic Gaussian-Alpha Control with Relative Stability and Gain Parameter for the Structural Benchmark Problems

This paper introduces a linear quadratic Gaussian (LQG)-α control with adjustable relative stability and gain parameter for the benchmark problems. The considered control algorithm is one active control methodology. It provides a various relative stability and introduces a gain parameter via a LQG design. The relative stability not only controls a guaranteed settling time for the system but also increases the controlled system robustness. The paper focuses on both wind- and earthquake-excited benchmark problems of the third generation. The simulation of this LQG-α control to these benchmark problems is provided. An additional simulation of the proposed control to a largely perturbed wind-excited benchmark problem is also provided. The control results, with respect to the evaluation criteria following the benchmark problems, are included for further comparison.     

Material Control System for the Manufactured Housing Industry

A manufactured home is a factory-built house constructed in a controlled factory environment according to federal standards known as the Department of Housing and Urban Development (HUD) code. The manufactured home shares approximately 20% of the total housing units in the United States and plays an important role in providing affordable housing. However, in terms of material engineering, advanced techniques are scarcely used in the manufactured housing (MH) industry. The current material flow and control systems are characterized as independent demand systems that are based on the personal experience of the material managers. Although independent inventory control systems are widely used in many manufacturing industries, these systems lead to a large amount of inventory and have many drawbacks for the MH industry. On the other hand, dependent inventory systems can reduce unfavorable inventory levels using new techniques and present substantial benefits for the MH industry. This paper applies lean inventory control systems and supply chain management techniques to the current systems of the MH industry and proposes a new framework of material control systems as one of the system management tools.     

混合煤气热值负偏差控制的开发与应用

阐述了在宝钢厂内混合煤气热值实行负偏差控制的必要性和具体的控制方法以及经济效益，它对钢厂的煤气调配与控制系统有一定的指导和推广意义。     

Control Structure Interaction of Electromagnetic Mass Damper System for Structural Vibration Control

To investigate the effect of control-structure-interaction (CSI) between the innovative electromagnetic mass damper (EMD) control system and the test structure, three computational models are first developed in this paper. Then, typical driving voltages are applied to the servo-amplifier of the EMD system to excite the structure and to examine the dynamic behavior of the EMD system when it is implemented into the structure. Furthermore, the test results are compared with the predictions based on the proposed parametric models, namely on-line examination. Finally, shaking table tests of structural seismic response control employing the EMD control system are conducted to validate and compare the effectiveness of those parametric models. All the test results have shown that only when the CSI effect (especially the higher-order CSI effect) is fully considered, can the on-line dynamical property of the EMD system be accurately predicted and its control performance fully exerted. This is essential to achieve the highest performance when employing such EMD systems in suppressing structural vibrations.     

铅烟气治理工程检测控制系统的研制开发

介绍了铅烟气治理工程检测控制系统计算机控制网络技术方案的形成过程,叙述了采用现场总线设备构成系统的先进性和大规模控制网络的技术问题。     

煤气柜自动化控制系统的开发与应用

济钢煤气柜自动化控制系统选用PLC作为基础自动化设备,采用RSlogix5000编程软件,运用梯形逻辑LD控制及功能块FBD相结合的编程方式来实现对高炉煤气柜、焦炉煤气柜、焦炉煤气加压机、油泵等设备的启停和安全保护。该控制系统满足了工艺需求,实现了整个工艺流程的自动检测、控制及管理监视,提高了煤气存储及输送的操作效率。     

Integrated Optimization of Control System for Smart Cylindrical Shells Using Modified GA

In this paper, modeling of the vibration of cylindrical shell components of space structures incorporating piezoelectric sensor/actuators (S/As) for optimal vibration control is proposed and formulated. The parameters of the control system, which include the placement and sizing of the piezoelectric S/As and the feedback control gains, were considered as design variables and optimized simultaneously. The effect of the amount of piezoelectric patches was investigated as well. The criterion based on the maximization of energy dissipation was employed for the optimization of the control system. A modified real-encoded genetic algorithm (GA) dealing with various constraints has been developed and applied to search for the optimal placement and size of the piezoelectric patches as well as the optimal feedback control gains. The results of three numerical examples, which include a simply supported plate, a simply supported cylindrical shell, and a clamped-simply supported plate, demonstrated significant vibration suppression based on the optimal design of the control system. It was also found that for specific controlled vibration modes, the optimal distribution of the piezoelectric S/As should be located at the areas separated by the nodal lines to achieve the optimal control effect. This finding would be useful for the practical design of smart structures.     

煤气储配控制系统的开发及应用

煤气储配站工艺设备主要包括转炉煤气、焦炉煤气、混和煤气和精制焦炉煤气系统4部分,其控制系统由2套PLC和3套HMI等设备组成,采用Concept 2.5编程软件和MP7.2监控软件,实现了煤气加压机的变频调节、混合煤气比值串级调节、煤气回收三通阀控制以及数据存储、数据处理和用户接口功能。操作简单方便、配置合理,满足了工艺要求。     

Choosing the Right Parameter for Single-Duct Constant Air Volume System Supply Air Temperature Reset

To improve system efficiency under part-load conditions, the supply air temperature set point for a single-duct constant air volume air handling unit (AHU) system is often reset based on either return air temperature or outside air temperature. Both reset strategies make engineering sense as long as the reset schedules are reasonable. Quite often the decision to use one over the other is made with the assumption that they will both achieve some energy savings. However, the impact of these two strategies on AHU energy consumption could be very different. An in-depth analysis and comparison of these two commonly used supply air temperature reset strategies for a single-duct constant air volume system is presented in this paper. It is shown that the reset strategy based on outside air temperature is inherently better than that based on return air temperature, with lower energy consumption and improved building comfort level.     

锌厂煤气站自动控制系统的开发应用

介绍了锡司锌厂煤气站大开环多逻辑组合的PLC自动控制系统的开发过程、系统组成 ,此系统运行稳定 ,调整灵活、控制效果满足生产要求。     

120 t转炉底吹供气系统控制模型与应用效果

根据鞍钢120 t转炉底吹供气系统的应用情况,基于PID调节算法建立了转炉底吹系统控制模型,可以实现供气管道气体流量的迅速、准确、稳定控制,满足生产工艺要求,使底吹元件在炉役期内可以保持稳定的形态和良好的透气性能,不易堵塞。该转炉进行底吹供气控制模型、设备和工艺优化后,钢水终点碳氧积由0.00316降低为0.00273,终点炉渣T.Fe含量降低1.69%,吨钢降低成本12.2元,经济效益显著。     

单系统高炉煤气管网调控装置的应用和创新

阐述了迁钢公司一期工程高炉煤气管网调控装置的应用和创新情况,改造后不仅弥补了设计缺陷,消除了重大安全隐患,提供了可靠保障,而且取得了相当可观的经济效益。