Evaluation of the control performance of hydronic radiant heating systems based on the emulation using hardware-in-the-loop simulation

This study presents an emulation method to evaluate the control performance of a hydronic radiant heating system. Since heat output in the system is dependent on the pressure loss and flow rate in the hydronic network, the interaction between thermal and hydronic models needs to be considered in the evaluation of the control performance. For this reason, many studies apply an integrated simulation to the evaluation; however, the analysis of the hydronic network sometimes leads to unreliable results due to the improper initial values for algebraic loops or the lack of modeling information on the hydronic components. In order to deal with this problem, this study suggests an emulation method, where the hydronic network is replaced by real hardware and the building physics is analyzed by a simulation. In the emulation, the pressure loss and flow rate in the hydronic network were represented by replacing the real pipe with equivalent hydraulic resistance. In addition, by using real control systems that connect the hydronic network and building simulation, the interaction between building physics and hydronic network could be considered in the evaluation. Based on the proposed emulation method, the performance of several control strategies was evaluated in terms of the accuracy and the rise time. The result shows that the individual control needs to be combined with hydronic balancing for more accurate control. Hydronic control devices such as a flow limit valve and a pressure differential control valve also proved to be helpful to the improvement of the control performance.     

A consistent modelling methodology for secondary settling tanks in wastewater treatment

The aim of this contribution is partly to build consensus on a consistent modelling methodology (CMM) of complex real processes in wastewater treatment by combining classical concepts with results from applied mathematics, and partly to apply it to the clarification-thickening process in the secondary settling tank. In the CMM, the real process should be approximated by a mathematical model (process model; ordinary or partial differential equation (ODE or PDE)), which in turn is approximated by a simulation model (numerical method) implemented on a computer. These steps have often not been carried out in a correct way. The secondary settling tank was chosen as a case since this is one of the most complex processes in a wastewater treatment plant and simulation models developed decades ago have no guarantee of satisfying fundamental mathematical and physical properties. Nevertheless, such methods are still used in commercial tools to date. This particularly becomes of interest as the state-of-the-art practice is moving towards plant-wide modelling. Then all submodels interact and errors propagate through the model and severely hamper any calibration effort and, hence, the predictive purpose of the model. The CMM is described by applying it first to a simple conversion process in the biological reactor yielding an ODE solver, and then to the solid-liquid separation in the secondary settling tank, yielding a PDE solver. Time has come to incorporate established mathematical techniques into environmental engineering, and wastewater treatment modelling in particular, and to use proven reliable and consistent simulation models.     

改善仿真混凝土塑性的两种方法

针对仿真混凝土材料脆性过大的特点,通过一系列的试验研究,提出了在原料中添加黏土或细橡胶颗粒来改善其脆性的2种方法.结果表明：与普通仿真混凝土相比,添加黏土可以改善仿真混凝土的脆性,增强其变形能力;依据黏土仿真混凝土的各力学参量随黏土含量变化规律的理论拟合曲线,可以确定符合某仿真试验模型所需要的黏土仿真混凝土的配合比;橡胶仿真混凝土在破坏过程中表现出良好的变形协调性,在承受最大荷载时未产生脆性断裂,而是呈现出经过较大塑性变形后的延性破坏现象.     

石油化工真火模拟训练装置池火模拟效果评价

真火模拟训练系统已在全球多个国家投入使用,是一套较为成熟且训练效果较好的实战训练设施,是当前消防部队推行实战化练兵的主要手段,也是未来消防员实战训练的发展趋势。真火模拟训练装置燃烧系统对实际火灾场景的重构效果直接影响着消防训练效果。本文基于理论模型、数值模拟、层次分析法等方法建立了石油化工真火模拟训练装置池火模拟效果评价方法。该评价方法不仅可以对真火模拟效果进行评价,还可以指导现有或拟建的真火模拟装置提高火灾事故模拟的还原度。     

Effect of thermostat and window opening occupant behavior models on energy use in homes

Existing dynamic energy simulation tools exceed the static dimension of the simplified methods through a better and more accurate prediction of energy use; however, their ability to predict real energy consumption is undermined by a weak representation of human interactions with the control of the indoor environment. The traditional approach to building dynamic simulation considers energy consumption as fully deterministic, taking into account standardized input parameters and using fixed and unrealistic schedules (lighting level, occupancy, ventilation rate, thermostat set-point). In contrast, in everyday practice occupants interact with the building plant system and building envelope in order to achieve desired indoor environmental conditions. In this study, occupant behavior in residential building was modelled accordingly to a probabilistic approach. A new methodology was developed to combine probabilistic user profiles for both window opening and thermostat set-point adjustments into one building energy model implemented in the dynamic simulation tool IDA Ice. The aim of the study was to compare mean values of the probabilistic distribution of the obtained results with a singular heating energy consumption value obtained by means of standard deterministic simulations. Major findings of this research demonstrated the weakness of standardized occupant behavior profile in energy simulation tools and the strengths of energy models based on measurements in fields and probabilistic modelling providing scenarios of occupant behavior in buildings.     

Cyber‐physical approach to the optimization of semiactive structural control under multiple earthquake ground motions

This paper presents a cyber‐physical approach to optimize the semiactive control of a base‐isolated structure under a suite of earthquakes. The approach uses numerical search algorithms to guide the exploration of the design space and real‐time hybrid simulation (RTHS) to evaluate candidate designs, creating a framework for real‐time hybrid optimization (RHTO). By supplanting traditional numerical analysis (i.e., finite element methods) with RTHS, structural components that are difficult to model can be represented accurately while still capturing global structural performance. The efficiency of RTHO is improved for multiple design excitations with the creation of a multiinterval particle swarm optimization (MI‐PSO) algorithm. As a proof‐of‐concept, RTHO is applied to improve the seismic performance of a base‐isolated structure with supplemental control. The proposed RTHO framework with MI‐PSO is a versatile technique for multivariate optimization under multiple excitations. It is well suited for the accurate and rapid evaluation of structures with nonlinear experimental substructures, in particular, those that do not undergo permanent damage such as structural control devices. The RTHO framework integrates popular optimization algorithms with advanced experimental methods, creating an exciting new cyber‐physical approach to design.     

Improving direct solar shading calculations within building energy simulation tools

The calculation of the shadows that building environment, building elements or shading devices may cast on the building envelope, plays a key role in load calculations and building energy simulation. Algorithms for solar shading calculations have direct repercussions on the accuracy of the results and the computational times of building simulation tools. This paper presents an improved method for direct solar shading calculations based on the projection of every polygon on a unique receiving surface and incorporates recent and high efficient algorithms to solve polygon intersections. Firstly, the method is shortly described. Secondly, it is validated by comparisons with other methods, experimental results and European standards. Then, a comparison test between the proposed and conventional methods is presented to assess computational speed improvement. Finally, the main advantages of the proposed method are discussed.     

Swelling rock behaviour in a tunnel: NATM-support vs. Q-support – A comparison

The Q-system is one of the most applied classification tool in modern tunnelling. After an exact evaluation of the parameters the rock support can be determined via the “Q-support chart”. In an already finished tunnel, mainly driven through limestone, the Q-system was tested under difficult geological conditions (shale–marl). Scope of the appraisal was a comparison of the support suggested by the “Q-support chart” with the real performed support after the NATM, regarding partly massive damages. This article is a contribution referring to the last publication on the topic “fitness of various engineering design tools” from [Palmstrom, A., Stille, H., 2007. Ground behaviour and rock engineering tools for underground excavations. Tunnelling and Underground Space Technology 22, 363–376].     

Fundamentals of performance-based building design

The paper formulates some fundamental principles of performance-based design (PBD), suggesting a conceptual framework and systematic approach suitable for application in most areas of building design, and in the development of simulation tools and performance test methods required in the design and assessment processes. A schematic algorithm, which has been developed for the common engineering approach, was helpful in identifying the inter-relation with the required knowledge-based databases and tools that are needed for proper implementation of PBD. It is also shown that this schematic algorithm can serve not only as a conceptual model but also as the basic framework for developing or adapting simulation tools that are intended for PBD and assessment. The last part of the paper demonstrates the application of the fundamental approach in several areas of building performance (fire safety, acoustics, moisture safety, indoor air quality, and durability), outlining in each area the main user needs, ensuing performance requirements, and the most significant capabilities required of adequate simulation tools, with an emphasis on input/output.     

Comparison between lighting performance of a virtual natural lighting solutions prototype and a real window based on computer simulation

This article discusses the measurement and simulation of a first generation prototype of Virtual Natural Lighting Solutions (VNLS), which are systems that can artificially provide natural lighting as well as a realistic outside view, with properties comparable to those of real windows and skylights. Examples of employing Radiance as a simulation tool to predict the lighting performance of such solutions are shown, for a particular case study of a VNLS prototype displaying variations of a simplified view of overcast, clear, and partly cloudy skies. Measurement and simulation were conducted to evaluate the illuminance distribution on workplane level. The key point of this study is to show that simulations can be used to compare an actual VNLS prototype with a hypothetical real window under the same sky scenes, which was physically not possible, since the test room was not located at the building׳s façade. It is found that the investigated prototype yields a less rapidly drop illuminance distribution and a larger average illuminance than the corresponding real window, under the overcast (52 lx compared to 28 lx) and partly cloudy (102 lx compared to 80 lx) sky scenes. Under the clear sky scene, the real window yields a larger average illuminance (97 lx) compared to the prototype (71 lx), due to the influence of direct sunlight.     

Real options in project coalitions in Dutch health care: two case studies of construction projects

Uncertainties affecting health organizations inevitably influence real estate decisions since real estate is required to facilitate the primary process in cure and care. Decisions have to be taken when there is little knowledge about the future. Therefore, flexibility is needed in the process of designing, constructing and operating real estate. Real options provide an approach to gain greater insight into flexibility. The aim is to analyse whether real options can be recognized in the real estate strategies of health organizations and what real options are provided by various forms of project coalition. Two case studies reveal that real options thinking can indeed be recognized in specific real estate strategies. The choice of certain real options is partly a result of the type of project coalition applied. Further development of real options thinking in real estate management in cure and care creates opportunities to deal with future uncertainties.     

Land-use aspects of air-quality management

This paper describes relationships between land-use and air quality. Until very recently, strategies directed toward improved air quality relied almost exclusively upon fuel switching and employment of emission control devices. However, air quality can also be influenced through alteration of land-use patterns. Engineers during their education are generally not exposed to land-use and other socio-economic aspects of air-quality management, although federal and state policy maker are increasingly recognizing that exclusive reliance upon emission control devices is not a very satisfactory long range approach. Alteration of land use as it affects the living, working, and transportation patterns must be considered as well.The first two sections of this paper attempt to provide guidelines within which land-use alternatives can be meaningfully evaluated. Air-quality standars and other aspects of air-quality management are described and interpreted within a quantitative cost-benefit framework.The rudiments of urban geography are also provided in order to introduce the readers to the economics and social forces which shape cities. The fundamental purpose is to make technologists aware of the conflict between these forces and plans for arbitrary changes in spatial patterns. Next, energy variables are proposed as a way to meaningfully relate land-use and environmental pollution with society's quest for affluence. The section on meteorology and dispersion models describes and criticizes the modeling tools and simulations currently available for the prediction of pollution dispersion. Finally, an urban simulation is used to integrate the foregoing material. The air-pollution propensities of various land-use alternatives are assessed.Thus a diversity of topics—all with the common thread of relating urban air quality to urban land use—is addressed. Rather than providing ready-made answers, this paper describes useful evaluation tools and provides insight into the complex problems and interactions involved.     

Integrating design tools for total building evaluation

To advance the use of expert systems and simulation tools, in fact to make them acceptable and usable to practitioners, a new approach is required in the development of an expert system and simulation tool environment. In this paper we detail the work currently taking place in New Zealand on the development of such an integrated environment for the use of multiple simulation tools and expert systems in the design process and for the analysis and refinement of the design as it progresses to a more concrete form.     

数据网络损伤模拟在检验实践中的探索

网络损伤是指在网络部署过程中，网络数据经过物理连接器、传输设备、网络设备传送过程中。必然引入的误差，包括常见的循环冗余码（CRC，Cyclical Redundancy Check）校验错误。也包括报文延时、乱序、丢失等。本文旨在介绍数据网络中损伤的特点。实验室模拟手段以及在检测实践中的意义和若干探索。     

Effects of real-time simulation feedback on design for visual comfort

Building performance simulations and models of human visual comfort allow us to predict daylight-caused glare using digital building models and climate data. Unfortunately, the simulation tools currently available cannot produce results fast enough for interactive use during design ideation. We developed software with the ability to predict visual discomfort in real time. However, we know little about how users react to simulation feedback presented in real time. In our study, 40 subjects with backgrounds in building design and technology completed two shading design exercises to balance glare reduction and annual daylight availability in two open office arrangements using two simulation tools with differing system response times. Subjects with access to real-time simulation feedback tested more design options, reported higher confidence in design performance and increased satisfaction with the design task, and produced better-performing final designs with respect to spatial daylight autonomy and enhanced simplified daylight glare probability.     

Simulation System for Analysis of Specialized Mobile Robots

The aim of this paper is to present the simulation system for analysis of specialized mobile robots, which is equipped with a supporting human operator (on–board or teleoperator) computer system. Simulation is performed in real time, using a computer system and a mobile robot. Visualization of the environment simulation, movements of the vehicle, and behavior of the human operator are done by computer animation and partly by a mobile robot and its physical environment. The performance of the control unit in different environmental conditions, including detection of obstacles using different sensors, can be observed using a mobile robot moving in a simulated environment configured according to experimental requirements.     

Entwicklung einer Toolbox zur zwei‐ und dreidimensionalen instationären thermischen Bauteilsimulation mit KARDOS

Development of a toolbox for the 2D and 3D transient thermal component simulation based on KARDOS. 2D and 3D dynamic thermal simulations of building components in combination with transient climate boundary conditions can approximate the real behaviour of a building component. The usual tools for multidimensional building component simulation are limited in the component geometry and can not be extended for multiphysics problems (e.g. hygrothermal analysis). For this reason, a toolbox for thermal component simulation, based on the FEM‐tool KARDOS, was developed. This toolbox comprises a pre‐processor, which is able to define and to discretise 2D and 3D complex component models. Starting from these models, the input files of KARDOS are generated automatically. Some applications shall illustrate the operating principle of the toolbox.     

Comparison of two simulation methodologies in modeling construction systems: Manufacturing-oriented PROMODEL vs. construction-oriented SDESA

To facilitate the practice improvement by use of simulation tools in construction, the present research generalizes the main characteristics that differentiate a construction system from a manufacturing system in light of simulation modeling. The PROMODEL simulation platform which is influential and popular in manufacturing is chosen for (1) validating the newly developed construction simulation platform called SDESA (the Simplified Discrete-Event Simulation Approach); and (2) identifying the differences between manufacturing and construction simulations by applying PROMODEL alongside SDESA to typical construction systems. In modeling a simple earth-moving operation and a real site operation integrating concreting and waste handling practices, the validity of SDESA is cross checked by the established PROMODEL and SDESA is found to be more flexible and straightforward in addressing construction systems in terms of (1) representing vehicle-loop work flows, (2) modeling resource transit times between various locations on site, (3) deriving resource utilization rates, and (4) learning efforts and application time requirements. The comparisons made can be taken as guidance for helping construction practitioners (1) to distinguish the modeling needs between construction and manufacturing simulations and (2) to select the suitable simulation tools for practice improvement.     

Role of simulation in construction management

Key applications are identified by the authors which include decision support systems for managing real life construction firms and projects as well as tools and devices for teaching theoretical concepts in construction management, training and team building.