Quantitative structure-pharmacokinetic relationship modelling.

This article presents the current methods in quantitative structure-pharmacokinetic relationship (QSPkR) modelling along with examples using chemicals of toxicological significance. The common method involves: (i) collecting pharmacokinetic data or determining pharmacokinetic parameters (e.g. elimination half-life, volume of distribution) by fitting to experimental data; and (ii) associating them with the structural features of chemicals using a Free-Wilson model. Such QSPkRs have been developed for a few series of chemicals but their usefulness is limited to the exposure scenario and conditions under which the experimental data were originally collected. The alternative approach involves the development of quantitative structure-property relationship (QSPR) models for parameters, blood:air partition coefficient, tissue:blood partition coefficient, maximal velocity for metabolism and Michaelis affinity constant, of physiologically-based pharmacokinetic (PBPK) models which are useful for conducting species, route, dose and scenario extrapolations of the tissue dose of chemicals. Mechanistic QSPRs are available for predicting tissue:blood and blood:air partition coefficients from molecular structure information of chemicals, whereas such approaches are not currently available for hepatic metabolism parameters. However, at the present time, the pharmacokinetics of inhaled volatile organic chemicals can be simulated adequately by considering the physiological limits of the hepatic extraction ratio (0-1) and molecular structure-based estimates of partition coefficients in the PBPK model. This current state-of-the-art of structure-based modelling of pharmacokinetics will advance with the development of QSPRs for other chemical-specific parameters of PBPK models. Integrated QSPR-PBPK modelling should facilitate the identification of chemicals of a family that possess desired properties of bioaccumulation and blood concentration profile in both test animals and humans.     

Simplified thermal and hygric building models: A literature review

This paper provides a systematic literature review on simplified building models. Questions are answered like: What kind of modelling approaches are applied? What are their (dis)advantages? What are important modelling aspects? The review showed that simplified building models can be classified into neural network models (black box), linear parametric models (black box or grey box) and lumped capacitance models (white box). Research has mainly dealt with network topology, but more research is needed on the influence of input parameters. The review showed that particularly the modelling of the influence of sun irradiation and thermal capacitance is not performed consistently amongst researchers. Furthermore, a model with physical meaning, dealing with both temperature and relative humidity, is still lacking. Inverse modelling has been widely applied to determine models parameters. Different optimization algorithms have been used, but mainly the conventional Gaus–Newton and the newer genetic algorithms. However, the combination of algorithms to combine their strengths has not been researched. Despite all the attention for state of the art building performance simulation tools, simplified building models should not be forgotten since they have many useful applications. Further research is needed to develop a simplified hygric and thermal building model with physical meaning.     

Three and more dimensional modelling in geo-engineering

Full three-dimensional modelling has been developed and is implemented for many sites where engineering structures are built. Such computer models of the subsurface allow for a more sophisticated handling of subsurface data leading to, for example, better dimensioning of geotechnical units, the evaluation of hazard and risk, foundation design, tunnel routing, planning and building, etc. Other applications are the back-analysis for completed civil engineering projects to verify the correctness of assumed and estimated ground models and parameters, the verification of the correctness of constitutive models for ground behaviour and the use of back analysis to improve building methodologies or equipment. The paper illustrates some of these advantages with a number of state-of-the-art applications of three-dimensional modelling in engineering geology and geotechnical engineering, highlighting a number of key issues when computer-aided 3D modelling is used: the definition of geotechnical (homogeneous) zones, scale and detail, uncertainty and likelihood of the developed model.     

Dynamic Process Modelling of Activated-Sludge Plants

This paper reviews the developments in process modelling, and outlines the benefits of dynamic modelling compared to steady-state modelling. The alternative uses of modelling, for design, operation and training, are included. The models covered are the COD-based models from the IAWQ models #1 and #2 and WRc's BOD-based model. The relevance of BOD modelling for practitioners, rather than academics, is discussed, and likely routes for the future development are presented.
The authors'practical experience using these models, principally under WRc's STOAT software, is also presented in the form of case studies - highlighting the experience of sampling programmes, calibration, validation and the continuing importance of the engineer's role.     

Continuous simulation of CSO emissions

Modelling is an essential method to predict the behaviour of various water systems in urban areas. A common problem of modelling these systems is that it is hardly possible to model them fully in a detailed way. The applications of existing hydrodynamic models are very data-intensive and time-consuming, particularly for continuous simulation using a long rainfall record. It is thus necessary to develop a new modelling approach which is correct in representing and efficient in dealing with the processes involved in urban water systems. SewSim is such a conceptual combined sewer overflow (CSO) emission model. SewSim has been developed using a dynamic programming package MATLAB and its toolbox SIMULINK. This paper presents some case studies using this model for continuous simulation.     

Analytical assessment of the structural performance of composite floors subject to compartment fires

The behaviour of composite steel–concrete building floors exposed to fire conditions is examined in this paper. The work represents part of a large project dealing with the numerical modelling and assessment of structural behaviour based on the fire experiments undertaken on a full-scale multi-storey steel-framed building at Cardington, UK. After providing brief details on the analytical tools and modelling approaches adopted in this investigation, the structural models constructed to simulate the fire tests are described and salient findings are highlighted. Although the detailed models provide some insight into key behavioural aspects such as the paramount influence of restraint to thermal expansion, the complex structural interactions that occur under fire conditions may not be readily demonstrated. In order to illustrate a number of underlying response mechanisms, the analytical results obtained from an idealised structural system, in which a single compartment is subjected to fire, are summarised. Assessment of the structural response using such simplified models provides a clear interpretation of the behaviour and, with further refinements, may be employed for undertaking detailed studies aimed at developing improved design recommendations.     

Integration of chaos theory and mathematical models in building simulation: Part I: Literature review

Current mathematical models in building research have been limited in most studies to linear dynamics systems. A literature review of past studies investigating chaos theory approaches in building simulation models suggests that as a basis chaos model is valid and can handle the increasingly complexity of building systems that have dynamic interactions among all the distributed and hierarchical systems on the one hand, and the environment and occupants on the other. The review also identifies the paucity of literature and the need for a suitable methodology of linking chaos theory to mathematical models in building design and management studies. This study is broadly divided into two parts and presented in two companion papers. Part (I) reviews the current state of the chaos theory models as a starting point for establishing theories that can be effectively applied to building simulation models. Part (II) develops conceptual frameworks that approach current model methodologies from the theoretical perspective provided by chaos theory, with a focus on the key concepts and their potential to help to better understand the nonlinear dynamic nature of built environment systems. Case studies are also presented which demonstrate the potential usefulness of chaos theory driven models in a wide variety of leading areas of building research. This study distills the fundamental properties and the most relevant characteristics of chaos theory essential to building simulation scientists, initiates a dialogue and builds bridges between scientists and engineers, and stimulates future research about a wide range of issues on building environmental systems.     

Numerical estimation of pillar strength in coal mines

Results of numerical modelling of failed and stable cases of pillars from Indian coal mines are reported in this paper. The complete procedure for modelling using FLAC^3D in the strain-softening mode is given. It is shown that estimation of pillar strength is possible using numerical modelling and it may provide a viable, and perhaps better, alternative to earlier conventional pillar strength approaches. Methods are given to estimate the large number of input parameters required in the models. Because of the paucity of rock characterisation and in situ stress data, some approximations and assumptions were made in all the cases based on earlier experience. The modelling work leads to the conclusion that such data are necessary for the success of this method. Areas for further research related to this subject are given in the end.     

Integration of chaos theory and mathematical models in building simulation: Part II: Conceptual frameworks

Current mathematical models in building research have been limited in most studies to linear dynamics systems. A literature review of past studies investigating chaos theory approaches in building simulation models suggests that as a basis chaos model is valid and can handle the increasing complexity of building systems that have dynamic interactions among all the distributed and hierarchical systems on the one hand, and the environment and occupants on the other. The review also identifies the paucity of literature and the need for a suitable methodology of linking chaos theory to mathematical models in building design and management studies. This study is broadly divided into two parts and presented in two companion papers. Part (I), published in the previous issue, reviews the current state of the chaos theory models as a starting point for establishing theories that can be effectively applied to building simulation models. Part (II) develop conceptual frameworks that approach current model methodologies from the theoretical perspective provided by chaos theory, with a focus on the key concepts and their potential to help to better understand the nonlinear dynamic nature of built environment systems. Case studies are also presented which demonstrate the potential usefulness of chaos theory driven models in a wide variety of leading areas of building research. This study distills the fundamental properties and the most relevant characteristics of chaos theory essential to (1) building simulation scientists and designers (2) initiating a dialogue between scientists and engineers, and (3) stimulating future research on a wide range of issues involved in designing and managing building environmental systems.     

Modelling multiple views on buildings

The building practice is characterized by its loose organization of the different participants, that each perform a specific role in a building project and have a specific view on the building project data. When modelling building information, it is useful to base the structure of a building model on these views. This can be done by the use of aspect models. This paper presents an approach in which aspect models are used to store view specific information. The approach is illustrated with an outline of a building reference model. The building reference model consists of a general kernel and view dependent aspect models. This model is first worked out for one decomposition level, the space unit level. After that the model is extended with other decomposition levels.     

A systems theoretic approach to second moment modelling of probabilistic engineering systems∗

A new approach to modelling probabilistic and stochastic engineering systems using graph theory is outlined. This approach emphasizes the introduction of probabilistic and stochastic concepts at the very beginning of the model building process. This is in marked contrast to past tendencies to add probabilistic concepts to the end of an otherwise deterministic model building process. The development of topological models founded on oriented probabilistic measurements is given. which leads to the identification of some useful statistical properties of the’ random interconnection equations’. The development of probabilistic component models is given, where a component can be characterized independently of other components. Methods for automatically building the second moment representation of the Mixed Nodal Tableau are discussed. The application of the above theory to the probabilistic analysis of a pipe network problem is briefly described.     

Modelling the Performance of Combined-Sewer Overflow Chambers

This paper reviews some of the physical model studies which have been carried out in the UK to determine the performance of combined-sewer overflow chambers. The topic of computational fluid dynamics is introduced and identified as a viable alternative to physical modelling. The limitations of both modelling approaches are discussed. It is concluded that the future of chamber modelling will be a combination of computational fluid dynamics and physical techniques.     

Ecological reflections in unbounded architecture

For many years, the environmental effort in Scandinavian residential building has taken the form of construction-related improvements and technical renewal. For example, the standard in insulation has been improved and, to an increasing extent, the supply of energy is being covered by alternative energy sources. However, 'green' accounts reveal that the building and its environmental standards are not the most important factors in the residence's consumption of resources. The most crucial factors are the residents and their behaviour.

Resource consumption in the residence is thus entirely dependent on the residents' habits, on their behaviour and life style. In the final analysis, it is our culture that becomes the topic for debate, as a direct consequence of environmental problems. Question marks are being placed alongside the consumption society and concomitantly alongside the entire occidental culture.

The upshot of this is that, sooner or later, environmental problems will eventually come to influence the architectonic design, which reflects the culture and the societal values from which such modelling originates. The environmentally oriented work can, in this way, be discussed in an architectonic context. This is the aim of the present paper: to describe urban ecological endeavours in a wide cultural perspective. This ought to make it possible to look at this work in conjunction with current tendencies in contemporary design. In order to understand the present day, however, it is necessary to start at some distance from it - with the Renaissance.     

Ecological reflections in unbounded architecture

For many years, the environmental effort in Scandinavian residential building has taken the form of construction-related improvements and technical renewal. For example, the standard in insulation has been improved and, to an increasing extent, the supply of energy is being covered by alternative energy sources. However, 'green' accounts reveal that the building and its environmental standards are not the most important factors in the residence's consumption of resources. The most crucial factors are the residents and their behaviour. Resource consumption in the residence is thus entirely dependent on the residents' habits, on their behaviour and life style. In the final analysis, it is our culture that becomes the topic for debate, as a direct consequence of environmental problems. Question marks are being placed alongside the consumption society and concomitantly alongside the entire occidental culture. The upshot of this is that, sooner or later, environmental problems will eventually come to influence the architectonic design, which reflects the culture and the societal values from which such modelling originates. The environmentally oriented work can, in this way, be discussed in an architectonic context. This is the aim of the present paper: to describe urban ecological endeavours in a wide cultural perspective. This ought to make it possible to look at this work in conjunction with current tendencies in contemporary design. In order to understand the present day, however, it is necessary to start at some distance from it - with the Renaissance.     

A Decision Support Tool for the Railway Industry Based on Computer Graphics and Intuitive Modelling Techniques

Abstract: The application of many operational research techniques employed by the railway industry requires as input a data model representing the geometrical, structural and operational characteristics of the railway network in question. However, constructing network models with the conventional methods requires a considerable amount of manual work that involves handling large amounts of both qualitative and predominantly, quantitative information. This paper presents an alternative approach for prototyping, constructing and querying railway models, incorporating interactive computer graphics. The presented approach allows the model builder to carry out the modelling task more quickly and accurately. After reviewing the transportation model building trends of the last decades, the authors present the characteristics of the proposed system, demonstrate its main functions and assess its impact on the efficiency of the modelling task.     

英国排水管网建模技术实例分析

基于排水管网水力模型软件(InfoWorks CS),介绍了一个英国小城镇排水管网建模过程.在实例中详述了英国管网建模规范、数据管理、模型构建以及模型检验等方面内容,最后针对我国现阶段的排水管网建模提出了值得借鉴的地方.     

State Space Analysis of Dynamic Closed Loop Environmental Systems

Structured, generalised, digital modelling and simulation software tools that enable engineers to more easily produce formalised, documented and transferable software for prediction of thermal performance and energy use in buildings are described. The basis for these tools is modern state-space analysis techniques that cast modelling equations into a vector-matrix form ideally suited for digital computation. An automated building modelling capability generates detailed and simplified models directly from building plans through use of a library of construction element models (walls, floors, etc.). A user-oriented program interface enables interconnection of the building model with other component models selected from a library of HVAC equipment. controls, internal load schedules, and weather data to construct a closed-loop system simulation. Theoretical considerations for the modelling methodologies implemented in these tools are discussed, along with techniques to systematically reduce the modelling complexity and simulation costs without loss of accuracy. Plans to implement the simulation tools on a minicomputer with an array processor are overviewed.     

A review of the application of SimuLink S-functions to multi domain modelling and building simulation

Multi domain modelling provides great opportunities for possible synergy between the building simulation domain and other scientific and technological domains. Although domains may have quite different models, they often use common mathematical representations, based on differential algebraic equations (DAEs) and/or ordinary differential equations (ODEs). This paper reviews the use of S-Functions in SimuLink for DAEs and ODEs modelling regarding building simulation and its potential for multi domain applications. It is concluded that ODEs are directly implementable using S-Functions in SimuLink. DAEs are indirectly implementable by a manual process of integrating Dymola/Modelica models. Examples from the literature confirm the great opportunities for the combined building thermal, geothermal, electrical and grid performance simulation.