Applying direct digital control

One particular aspect of a wide range of HVAC research at the US Center for Building Technology concerned interfacing DDC with the pneumatic system for one of the existing air handling units at the CBT building itself. Using solenoid air valves induced both positive and negative air leaks in the pneumatic system; this did not occur with motorised pressure regulators, though these produced a time delay whenever the regulator's direction of rotation was reversed. Details are given of an adaptive PI algorithm with a self-tuning regulator approach, developed at CBT and implemented on the air handler in question. From the experience, it is strongly recommended that such an algorithm should be implemented on a positional basis.     

小型气力垃圾输送系统的设计与应用研究

近年来气力垃圾输送系统作为一种新型的节能环保科技已在国内多个新城市和医院等大型建设项目中获得成功应用,但在小型住宅项目中由于系统设计、配套、造价等问题一直难以推广和应用。文章针对小型住宅建设工程的项目特点,结合大型系统的工程实践经验,对小型气力垃圾输送工程应用的系统负荷进行了理论计算,并对系统中的中央收集站、垃圾储存和管网设备进行了优化设计,推出了小型住宅项目的系统设计和应用模型,从而简化系统设备构造,降低系统实施的土建配套要求,同时也减少了系统设备投资造价,对小型系统的实际应用具有重要的指导意义。     

Control of marine vehicles with pneumatic compliances

This paper is concerned with the use of pneumatic compliances to control the heave, roll and pitch motions of marine vehicles when disturbed by operational loads. The pneumatic compliances are in the form of open bottom air tanks attached to the vessel at the water line and extending above and below still water level. Each tank traps a volume of air above its internal water level. Active operation of these tanks involves controlling the amount of air trapped within the tanks. The air exerts varying forces and moments on the vessel which may be used to counteract disturbing forces. This paper describes a time domain method of dynamic analysis that is used to investigate the performance of such a system. Three application studies are presented which involve the suppression of motion due to vessel loading and crane operation on semisubmersible and monohull vessels.     

人防工程竣工验收评估系统设计与实现

为提高人防工程竣工验收评估工作的规范化和自动化水平,设计并实现了人防工程竣工验收评估系统。给出系统的总体设计方案,并确定了系统的功能结构。在对人防工程常见质量问题广泛调研的基础上,结合人防工程相关标准规范,制定了人防工程竣工验收评估的指标体系。使用层次分析法,计算得到了指标体系中各指标的权重,并对系统使用的评估算法进行了详细阐述。最后,基于微软VisualStudio开发平台实现了系统的各个功能模块。     

Pneumatic stiffness and damping in air-supported structures

This paper presents an analytical investigation of pneumatic effects in air-supported structures. The analysis applies only to volume-displacing modes of motion. The analysis includes the effects of pressure fluctuations on leakage flow rate and on the delivery flow rate of the fans used to ventilate and pressurize the building. These effects give rise to pneumatic damping which can become very large for large air-supported structures such as sports stadia; pneumatic damping can be significant even for smaller air supported structures. Pneumatic stiffness is important for virtually all air-supported structures.The relative importance of pneumatic stiffness and damping and of acoustic damping can easily be estimated for a specific structure by using information presented in the paper. The differential equation governing pneumatic effects could easily be incorporated into the dynamic analysis of an air-supported structure.     

Assessing the control systems available

This paper from the US Army Corps of Engineers’ Construction Engineering Research Laboratory (CERL) reports on the measured performance of pneumatic controls used for heating and air conditioning, giving the advantages and drawbacks of pneumatic, electronic and digital control. Simulating the effect of different control strategies on energy comsumption reveals greater variations than normally assumed. The report finally recommends the use of high quality electronic controllers coupled through transducers to pneumatic valve and damper actuators. For this, CERL has devised a reliable control panel which gives quick diagnosis of performance; it can be retrofitted as part of a simple control for variable air volume systems.     

Assessing the control systems available

This paper from the US Army Corps of Engineers' Construction Engineering Research Laboratory (CERL) reports on the measured performance of pneumatic controls used for heating and air conditioning, giving the advantages and drawbacks of pneumatic, electronic and digital control. Simulating the effect of different control strategies on energy comsumption reveals greater variations than normally assumed. The report finally recommends the use of high quality electronic controllers coupled through transducers to pneumatic valve and damper actuators. For this, CERL has devised a reliable control panel which gives quick diagnosis of performance; it can be retrofitted as part of a simple control for variable air volume systems.     

Automobile gross emitter screening with remote sensing data using objective-oriented neural network

One of the costs of Taiwan's massive economic development has been severe air pollution problems in many parts of the island. Since vehicle emissions are the major source of air pollution in most of Taiwan's urban areas, Taiwan's government has implemented policies to rectify the degrading air quality, especially in areas with high population density. To reduce vehicle pollution emissions an on-road remote sensing and monitoring system is used to check the exhaust emissions from gasoline engine automobiles. By identifying individual vehicles with excessive emissions for follow-up inspection and testing, air quality in the urban environment is expected to improve greatly. Because remote sensing is capable of measuring a large number of moving vehicles in a short period, it has been considered as an assessment technique in place of the stationary emission-sampling techniques. However, inherent measurement uncertainty of remote sensing instrumentation, compounded by the indeterminacy of monitoring site selection, plus the vagaries of weather, causes large errors in pollution discrimination and limits the application of the remote sensing. Many governments are still waiting for a novel data analysis methodology to clamp down on heavily emitting vehicles by using remote sensing data. This paper proposes an artificial neural network (ANN), with vehicle attributes embedded, that can be trained by genetic algorithm (GA) based on different strategies to predict vehicle emission violation. Results show that the accuracy of predicting emission violation is as high as 92%. False determinations tend to occur for vehicles aged 7-13 years, peaking at 10 years of age.     

PSO-based Elman neural network model for predictive control of air chamber pressure in slurry shield tunneling under Yangtze River

The excavation face stability is crucial for safety and risk management in slurry shield tunneling, especially for the river-crossing tunnel. To avoid face collapse or blow-out, shield operators need to keep air chamber pressure balanced using their own experience, which would be difficult, discontinuous and less reliable in the process of construction. Considering the disadvantage of the manual control process, this paper presents a predictive control system for air chamber pressure in slurry shield tunneling using Elman neural network (ENN) model. It mainly contains a theoretical model, an ENN predictor and an ENN controller to set optimal control parameters automatically tracking the desired air chamber pressure. Moreover, to improve the learning capability of ENN model, a particle swarm optimization (PSO) algorithm is implemented. This system has been tested with collected data of slurry shield operation parameters in the Yangtze riverbed metro tunnel project in Wuhan, China. Analysis revealed that the predictive control system using PSO-based Elman neural network model in this paper has the potential for enhancing face stability in slurry shield tunneling.     

Development of a multiple objective planning theory and system for sustainable air quality monitoring networks

Air quality monitoring data are important bases for air quality management strategies planning and performance assessment. Therefore, the environmental protection authorities need to plan the air quality monitoring network effectively. However, in Taiwan, the national Environmental Protection Administration (EPA) and some county environmental protection bureaus (EPB) separately installed their own monitoring stations. This study developed an integrated methodology and computer system for planning air quality monitoring networks. The environmental, social, and economic objectives and sub-objectives, and their weights were identified using system analysis and multiple objective planning, based on the principles of sustainable development. A multiple objective optimization model and procedure for sustainable air quality monitoring networks planning are developed in this study. According to the procedure, a multiple objective planning system for sustainable air quality monitoring networks (MOPSSAQMN) is developed using computer software based on the modified bounded implicit enumeration algorithm with the constraint arrangement method. The air quality monitoring network of Taoyuan County, in northern Taiwan, was used as a case study to demonstrate the proposed method. Two satisfactory alternatives based on different conditions were generated using MOPSSAQMN. The compared results show that this study generated better alternatives than the current monitoring network. An installation schedule for the alternative was proposed, and its first step is now being implemented by the EPB of Taoyuan County Government. The procedure and computer system developed in this study can be used to assist the competent authorities to devise good and different alternatives for air quality monitoring networks planning.     

汽车空调压缩机耐久性试验台运行稳定性试验研究

就系统匹配对汽车空调压缩机耐久性试验台运行工况稳定性的影响进行了试验研究.结果表明,压缩机连续运行时,制冷剂采用手动阀调节后工况的稳定性明显好于采用热力膨胀阀时的情况,此时调节冷却水量用的电动调节阀和气动调节阀对工况稳定性影响相差无几;间歇运行时,无论是热力膨胀阀还是手动阀,即便压缩机通电时间最长,仍达不到设定工况,特别是低速的断续尤为明显,而使用气动阀就能很好地解决这一问题.     

多台空压机联动控制系统的设计

建筑用空压机功率大、能耗高,如何尽可能降低空压机能耗是很多建筑施工单位极为关注的技术改造内容。为降低空压机能耗并节约建筑成本,设计出多台空压机联动控制方案,通过控制器实时检测储气罐气压,分析当前工作风镐的数量,动态调整工作空压机的数量,实现以最少空压机工作维持所需工作气压。运行结果表明,该控制系统显著降低了能耗,并提高了建筑用空压机自动化管理水平。     

空调系统在线辨识算法的研究

空调系统可以看成是具有时变特性的一阶惯性加延迟的对象,针对递推最小二乘法只能辨识对象的过程参数而无法辨识延迟时间的问题,提出了一种基于最速下降法的在线辨识算法,可以同时辨识出时变情况下空调系统对象的过程参数和延迟时间。以空气焓差法试验台测试室的温度控制系统作为仿真对象对该算法进行了验证,结果表明,该算法具有较高的辨识精度,而且性能稳定。     

新型气动PCM控制系统的试验研究

本对采用三个气源的新型气动控制系统，进行了详细地试验研究，针对试验中出现的问题，提出了一些解决措施，试验结果表明：新型气动ＰＣＭ控制系统能获得±０．３ｍｍ的定位精度，并具有较好的跟踪性能。     

Real climate experimental study of two double window systems with preheating of ventilation air

This paper aims to characterize the thermal performance of a window system that consists in doubling an existing window, converting it into a ventilated double window. The air coming from the outside circulates upwards through the channel between windows and enters the building through a vent on the top of the window's case. A series of experimental measurements was conducted in a test cell exposed to real outdoor weather conditions located in a mountain region at Centre of Portugal, during heating season in order to determine how this window system can act as a heat exchanger. It was found that such window system act as an efficient heat exchanger using transmission heat losses and solar radiation to preheat ventilation air, thus reducing the building's operational energy costs. An average of about 19 m³/h of air flow rate was found with an air temperature increment within the air gap of about 6 °C, during night-time, for an indoor/outdoor temperature difference of about 16 °C. Air temperature increment reached up to 12 °C using a plastic shutter. With solar radiation, the average of that increment was about 10 °C. This is a simple and cheap building technology which can be implemented both in new and existing buildings.     

Model-based optimal supervisory control of chilled ceiling displacement ventilation system

The aim of this paper is to develop an optimized online supervisory control predictive tool for the chilled ceiling displacement ventilation (CC/DV) system to minimize energy consumption while creating the best indoor air quality (IAQ) and thermal comfort. The online controller is designed to operate under an optimized control strategy with five control set points. A dynamic multi-variable objective cost function is formulated for the supervisory control of the CC/DV system performance indices and constraints, and is solved using genetic algorithm. The design of the optimized controller takes into consideration the response time of three-way valves, reheat, and supply fan to employ signaled changes in set points.The developed online controller response to load changes and its ability to change system set points to optimally meet unknown load and constrains are tested and evaluated under the simulated ‘real life’ environment for a case study. It is shown that the implemented online optimized controller is robust, and its development contributes to improved CC/DV system energy efficiency.     

美国的医院标准和手术室设计

美国思路强调以手术室细菌控制的综合措施减少感染风险，不片面强调净化级别；认为净化只是一种手段，无菌程度才是其控制目的和结果的体现；强调以经济有效的方法实施手术室洁净送风系统，既然单向流设施不能证明可以地降低术后感染率，就不宜推广。美国的标准和丰富实践基于其特定的国情，许多地方值得我国医院洁净手术室建设和改造借鉴。     

用机考方式进行一级建造师执业资格考试的探讨

分析了现行一级建造师执业资格考试存在的问题,借鉴以托福为主的各类计算机辅助考试,基于计算机技术的机考流程及特点,论证开展一级建造师执业资格考试机考方式的优势及可行性,并设计机考考试制度。     

Model-based design and experimental validation of active vibration control for a stress ribbon bridge using pneumatic muscle actuators

This paper describes the development of an active vibration control system for a light and flexible stress ribbon footbridge. The 13 m span carbon fiber reinforced plastic (CFRP) stress ribbon bridge was built in the laboratory of the Department of Civil and Structural Engineering, Berlin Institute of Technology. Its lightness and flexibility result in high vibration sensitivity. To reduce pedestrian-induced vibrations, very light pneumatic muscle actuators are placed at handrail level, introducing control forces. First, a reduced discretized analytical model is derived for the stress ribbon bridge. To verify the analytical prediction, experiments without feedback control are conducted. Based on this model, a delayed velocity feedback control strategy is designed. To handle the nonlinearities of the muscle actuator, a subsidiary force control is implemented. Then the control performance from numerical simulation is verified by experiments under free vibration. As a result, analytical analyses agree well with experimental results. It is demonstrated that handrail-introduced forces can efficiently control the first mode response.     

Energy-efficient HVAC systems: Simulation–empirical modelling and gradient optimization

This paper addresses the energy saving problem of air-cooled central cooling plant systems using the model-based gradient projection optimization method. Theoretical–empirical system models including mechanistic relations between components are developed for operating variables of the system. Experimental data are collected to model an actual air-cooled mini chiller equipped with a ducted fan-coil unit of an office building located in hot and dry climate conditions. Both inputs and outputs are known and measured from field monitoring in one summer month. The development and algorithm resulting from the gradient projection, implemented on a transient simulation software package, are incorporated to solve the minimization problem of energy consumption and predict the system's optimal set-points under transient conditions. The chilled water temperature, supply air temperature and refrigerant mass flow rate are calculated based on the cooling load and ambient dry-bulb temperature profiles by using the proposed approach. The integrated simulation tool is validated by using a wide range of experimentally collected data from the chiller in operation. Simulation results are provided to show possibility of significant energy savings and comfort enhancement using the proposed strategy.