Controlling sewer systems – a critical review based on systems in three EU cities

The term Real Time Control (RTC) is widely used to describe all types of control systems in sewer systems. Today the term covers everything from the simplest to the most advanced types of control systems, making it difficult to communicate about sewer system control in a precise manner, as well as search and find specific types of control systems for comparison. Through a survey of implemented control systems in three EU cities today and with the perspectives of current research within the field of sewer system control, the needs for a new control system design framework is identified. With the basis of existing frameworks for control system design, a new time-scale dependent framework is proposed. We believe this comprehensive time-scale dependent framework can help water utilities to retrofit and design new control solutions and facilitate knowledge sharing about existing designs.     

Sizing of residential μCHP systems

Combined heat and power (CHP) is a well-known technique for producing heat and power simultaneously onsite. However, the micro level of this technology has just been recently introduced around the world, and expected to widely spread. Therefore, identifying the optimal size of such systems would give them the potential for being more beneficial.In this paper, a generic deterministic linear programming model, which aims to minimize expected annual cost of the system, has been developed. This model is capable of optimally determining the optimal size (electrical rating) of a micro CHP (μCHP) unit and the optimal size (thermal rating) of a back-up heater for any given residential demand regardless of the type of μCHP technology.An investigation has been conducted to identify economically the optimal μCHP investment for three typical residential dwellings in England. The four candidate μCHP technologies that have been considered in this paper are: internal combustion engine (ICE), Stirling engine (SE), solid oxide fuel cell (SOFC), and proton exchange membrane fuel cell (PEMFC). Sensitivity analyses have been conducted to understand the influence of some important key parameters on decision making regarding the deployment of residential μCHP systems.     

Do sustainable community rating systems address resilience?

Extensive damages and numerous casualties are produced by natural disasters and hazards in urban areas. Hence, the absorption, recovery and adaptation to them through resilience are highly necessary to ensure operation and enhancement of urban systems. The significance of urbanization led to launch some tools such as BREEAM Communities, CASBEE for Urban Development, DNGB Urban Districts, Green Star Communities, LEED for Neighbourhood Development or STAR Community to promote sustainable development in communities and cities. After selecting the most relevant community rating systems, this research determined their adequacy to handle urban challenges by benchmarking them against the major international efforts and some relevant resilience assessment tools extracted from the study of eight global frameworks. Thus, the Sendai Framework and the 2030 Agenda represented the former, whilst the latter considered the City Resilience Index and the City Resilience Profiling Tool. The findings of this investigation revealed that the indicators of STAR Community and BREEAM Communities reflected the highest level of correspondence with the resilience assessment frameworks. However, the existence of prominent gaps in all the screened community rating systems suggests the need for developing a new tool involving both resilience and sustainability.     

Numerical analyses in the design of umbrella arch systems

Due to advances in numerical modelling, it is possible to capture complex support-ground interaction intwo dimensions and three dimensions for mechanical analysis of complex tunnel support systems,although such analysis may still be too complex for routine design calculations. One such system is theforepole element, installed within the umbrella arch temporary support system for tunnels, whichwarrants such support measures. A review of engineering literature illustrates that a lack of designstandards exists regarding the use of forepole elements. Therefore, when designing such support, designersmust employ complex numerical models combined with engineering judgement. With referenceto past developments by others and new investigations conducted by the authors on the Driskos tunnelin Greece and the Istanbul metro, this paper illustrates how advanced numerical modelling tools canfacilitate understanding of the influences of design parameters associated with the use of forepole elements.In addition, this paper highlights the complexity of the ground-support interaction whensimulated with two-dimensional （2D） finite element software using a homogenous reinforced region,and three-dimensional （3D） finite difference software using structural elements. This paper further illustratessequential optimisation of two design parameters （spacing and overlap） using numericalmodelling. With regard to capturing system behaviour in the region between forepoles for the purpose ofdimensioning spacing, this paper employs three distinctive advanced numerical models： particle codes,continuous finite element models with joint set and Voronoi blocks. Finally, to capture the behaviour/failure ahead of the tunnel face （overlap parameter）, 2D axisymmetric models are employed. Finally,conclusions of 2D and 3D numerical assessment on the Driskos tunnel are drawn. The data enriched casestudy is examined to determine an optimum design, based on the proposed optimisation of designparameters, of forepole elements related to the si     

Assessing the implementation of BIM – an information systems approach

Much attention has been paid to measuring the perceived benefits of Building Information Modelling (BIM). Yet despite an increase its adoption throughout the construction industry, important links between implementation, support and benefits are yet to be explored. We examine the constitutive elements of the BIM implementation process of two case studies implementing and using BIM: the first is a large urban regeneration project, and the second is a healthcare project. A well-recognised model of system success is mobilized from the field of information systems (ISs) to reveal that irrespective of project size and type, BIM benefits are confined to technically discrete productivity and efficiency gains when there is limited focus on the organizational aspects of BIM adoption. This paper focuses on the disconnections between organizational and project level BIM implementation using the DeLone and McLean Model as an analytical framework to systematically examine the benefits of BIM to each project in relation to the implementation approach employed. This study highlights the significance of these interdependencies and argues for a more comprehensive approach to BIM benefits capture that recognises this to usefully inform implementation strategy development.     

Come back sociotechnical systems theory,all is forgiven …

Why, despite all the effort and expense, do engineering systems sometimes show an abject lack of resilience, with the smallest of human failures being the difference between normality and a calamitous disaster? If people made the kind of rational choices tacitly designed into our Civil Engineering endeavours, then a fair slice of humanity's grand challenges would probably disappear. Sociotechnical systems (STS) theory was an approach developed to address these matters. Several large firms embraced the principles to give rise to organisations that were highly adaptable, flexible, responsive, and above all resilient. What we have in STS theory is a powerful demonstration of how to harness the emergent edge-of-chaos properties of humans, jointly optimised with engineering, which could offer a radical new approach to resilience.     

Ecological Networks: Connecting environmental,economic and social systems?

Ecological networks for different spatial scales (international to sub-regional) are being defined and realized throughout Europe. Historically they have been focused on nature conservation, but they may offer a mechanism whereby a holistic, integrated and long-term approach to regional and sub-regional sustainable development can be promoted. Economic, social and environmental factors operate at different spatial and temporal scales, presenting challenges to those wishing to develop an ecological network. A case study based on the development of an ecological network for Cheshire, a sub-region of the European Region-North West (UK), demonstrates how environmental issues might be integrated with social and economic drivers of change. A framework for an ecological network is proposed by combining an outline model of the socio-ecological system within Cheshire with a checklist that can be used to assess the sustainable management of a landscape.     

Analysis of seismically-isolated two-block systems using a multi–rocking-body dynamic model

A novel multibody rocking model is developed to investigate the dynamic response of two stacked rigid blocks placed on a linear base isolation device. The model is used to investigate the dynamic response of a realistic statue-pedestal system subject to pulse-like ground motions. The analysis shows that, in general, base isolation increases the safety level of the rocking system. However, for large period pulses or small size blocks, the isolator can amplify the ground motion, resulting in a lower minimum overturning acceleration than for the nonisolated system. Further, the amplification or shock spectrum of a linear mass-dashpot-spring oscillator, was found to be the reciprocal of the minimum nondimensional overturning acceleration of the investigated rocking system. Novel rocking spectra are obtained by normalizing the frequency of the pulse by the frequency of the isolator. The analysis also demonstrates how the dynamic response of the two stacked blocks is equivalent to that of a single-block configuration coincident with the whole system assumed monolithic or the upper block alone, whichever is more slender.     

Indirect evaporative cooling potential in air–water systems in temperate climates

Recent developments have prompted a review of evaporative cooling technology as an effective means of cooling modern deep plan buildings. Prominent among these developments is the success of high temperature sensible cooling systems, particularly, chilled ceilings, which require a supply of cooling water at 14–18 °C. Crucial to the success of evaporative cooling technology, as a significant means of cooling in modern applications, is the ability to generate cooling water, in an indirect circuit, at a temperature which closely approaches the ambient adiabatic saturation temperature (AST) or wet bulb temperature (WBT). Recent experimental research has demonstrated that it is technically viable to generate such cooling water at a temperature of 3 K above the ambient AST.While the frequency of ambient AST occurrence can be obtained from meteorological sources, there is little in-depth analysis of the potential for this form of cooling water generation, based on the approach temperatures which have now been shown to be viable. The decision to use an evaporative cooling system depends largely on an assessment, in-depth, of net energy saved against capital expended. Such an assessment requires detailed data on the availability of cooling water, generated by evaporation, for each location. This paper quantifies evaporative cooling availability in-depth for a northern and southern European city, Dublin and Milan and suggests a method of analysing such data for any world wide location, for which suitable meteorological records are available. The paper, incorporates recent experimental research findings and bases the availability analysis on meteorological test reference weather year data.The results of this research confirm a major potential for the generation of cooling water by evaporative means, which can be used to provide effective cooling of deep plan buildings by means of contemporary water based sensible cooling systems, such as fan coil systems, radiant chilled ceiling panels and ceiling cooling convectors (chilled beams). While the technique offers most potential in locations with a northern European temperate climate, it has significant potential to contribute to cooling in some southern European cities, during the non-summer months and also at other times, particularly where load shaving techniques are incorporated.     

Embedding built environments in social–ecological systems: resilience-based design principles

Globalization, the process by which local settlements and ecosystems are becoming linked in a global network, presents policy scientists and planners with difficult design challenges. Coping with either natural or built environments in isolation is extremely challenging in its own right (e.g. built environments at different scales: a single building, a collection of buildings, a neighbourhood or a city are in themselves very complex). In the Anthropocene era, where human activities shape the planetary system in which built and natural environments are becoming more tightly linked across scales, these complex systems need to be considered as elements in a global network, i.e. as a coupled social–ecological system (SES) at the global scale. In the context of this spiralling complexity, multi-scale and multilevel processes become more important and design/management problems become extraordinarily difficult. Preliminary ideas are explored for how research on this multilevel design problem might proceed. Specifically, based on combining insights from a collection of theories and models based on resilience and robustness concepts, the basic elements of a new approach are presented that recognizes the importance of self-organizing processes at multiple scales and emphasizes the use of feedbacks to link these processes across scales.     

How does industry specialization affect the efficiency of regional innovation systems?

This study analyzes the relationship between the specialization of a region in certain industries and the efficiency of the region in generating new knowledge. The efficiency measure is constructed by relating regional R&D input and output. An inversely u-shaped relationship is found between regional specialization and R&D efficiency, indicating the presence of externalities of both Marshall and Jacobs’ type. Further factors influencing efficiency are externalities resulting from high R&D intensity of the local private sector as well as knowledge from local public research institutions. The impact of both the specialization and the additional factors is, however, different for regions at different efficiency levels.     

Cost–benefit analysis for optimal distributed generation placement in distribution systems

This paper presents an optimisation method to determine optimal allocations of distributed generation (DGs) and capacitors based on maximisation of a profit/worth analysis approach. The optimal locations and sizes of DGs and capacitors have been determined by minimising the power distribution loss. This method considers various technical and economic factors such as line losses, sizes of DGs and capacitors at optimal locations, investment costs, operating costs and maintenance costs of DG and capacitor to achieve the objective for a predetermined number. The electricity market price of grid power has been considered to recover initial investment in a specified time period. The improvement in the voltage profile of the system has also been considered in this work. The particle swarm optimisation technique has been used to solve the optimal placement of DGs and capacitors to maximise the profit. The proposed technique is tested on 33-bus and 69-bus test systems.     

Calibration of a lumped simulation model for double-skin façade systems

The paper describes the calibration of a simulation model of double-skin façade systems with controlled rotating louvers and ventilation openings. The approach is based on a parameter estimation technique and in situ monitoring of a full-scale element mounted on the south facing façade of an existing building. Contrary to similar work that attempts to derive the behavior from detailed modeling of the physical transport phenomena, the new approach is based on a postulated “minimalistic” lumped model, which is calibrated on in-situ measurements. It is found that the calibrated model is surprisingly accurate and ideally suited for use in the ensuing optimal control and performance studies.     

Rationalisation and reliability improvement of fire-fighting systems – the Novi Sad case study

Water supply systems are commonly used to supply fire-fighting water in most EU countries. To provide fast access to water, the standard practice is to install a huge number of hydrants along the entire water supply network. Pipe diameters and working pressures in the network are designed for a combination of the maximum hourly water demand and fire-fighting needs. However, in poorly managed water supply systems most of the hydrants are out of order. Although hundreds of hydrants exist in the network, the reality is that fire water tankers are usually refilled at just a few locations that are equipped with reliable hydrants maintained by the fire brigades. This paper presents a somewhat different approach for the provision of fire-fighting water. The approach discussed in the paper is based on the concept being introduced in the city of Novi Sad, Serbia, by cooperative efforts of the municipal Water Supply and Sewerage Company and the fire-fighting service. In addition to presenting the experience gained in the case study, some generic conclusions are drawn. As an alternative to having a number of unreliable and small hydrants distributed throughout the network, the new concept proposes the construction of several strategically positioned filling stations, with high-flow-rate pillar hydrants and good access roads for the manoeuvering of fire water tankers. If properly designed and distributed around the city, such filling stations would increase the reliability of fire-fighting operations. The filling stations' design methodology presented in this paper is composed of a fire-risk spatial assessment, a hydraulic check of water supply network operations and a worst-case traffic load analysis. By employing the proposed methodology, not only can the reliability of fire-fighting operations be increased, but if accepted and implemented the methodology can lead to leakage reduction and improvements in water quality and the system's energy efficiency. In the test case of Novi Sad, a large number of hydrants were replaced by 14 filling stations that have been designed and constructed. A hydraulic model of the water supply network was calibrated using pressure-drop tests and flow capacity measurements of the existing hydrants. The model was used to examine the performance of the designed filling stations during their parallel operation. The paper presents the results of the test application and recommendations for the possible implementation of the concept.     

Two oil spills—interrelation between the socioeconomic structure and impact on seafood marketing systems

Little research has been done, to date, on the socioeconomic effects of oil spills. The socioeconomic investigations which were carried out in connection with the “Saint Peter” oil spill off the Colombian/Ecuadorian coast, and the “Urquiola” oil spill at La Coroña harbor in north‐western Spain have provided an opportunity to document different effects on the seafood marketing systems in the two communities. The differences of the impact of the oil spills permitted an insight into the interrelation between socioeconomic factors both with respect to the effects produced and the degree of success of the corrective measures where such were implemented.     

Information,rational expectations and network equilibria — an analytical perspective for route guidance systems

This paper tries to provide with a unified framework for understanding how drivers act in response to exogenously provided route guidance information; and how they form subjective expectations on traffic conditions from repeated learning. The learning problems are placed in the context of iterative adjustment processes which achieve equilibrium if drivers have rational expectations. Route choice models with rational expectations find a new justification since the models appear as the limits of drivers' learning procedures. This paper is also devoted to the question of whether route guidance information can convey substantial information to drivers even if drivers behave with rational expectations of their environment. The author also tries to propose a framework for designing the optimal route guidance systems.This paper was presented in draft form at an International Workshop on Trade, Knowledge and the Network Economy, held in December 1992 at Mallacoota, Australia.     

Transitioning to sustainable urban water management systems: how to define expected service functions?

Sustainable water management is a worldwide challenge for the twenty-first century. It involves replacing traditional management approaches with a new concept, often referred to as sustainable urban water management (SUWM). This paradigm shift means that SUWM systems must include new services, some of which have already emerged. However, no publications have presented the expected SUWM system in terms of the full range of services it would need to include, and no publications have proposed a method for identifying the services the system must provide. This paper proposes a method for identifying these services and presents a generic petal diagram to represent the service functions of the SUWM system. Moreover, this paper presents a new method for defining these services in a specific territory. This method is based on the confrontation between a general representation and the objectives of the stakeholders in a given system in a given territory. The method is illustrated with a full-scale case study on the Doua eco-campus (Lyon University). This method is intended to aid practitioners to manage its system and to transition to SUWM. It is designed to improve the transparency of decision formulation and to involve stakeholders in the process.     

How effective is intermittent chlorination to control adult mussel fouling in cooling water systems?

Mussel control in cooling water systems is generally achieved by means of chlorination. Chlorine is applied continuously or intermittently, depending on cost and discharge criteria. In this paper, we examined whether mussels will be able to survive intermittent chlorination because of their ability to close their valves during periods of chlorination. Experiments were carried out using three common species of mussels: a freshwater mussel, Dreissena polymorpha, a brackish water mussel, Mytilopsis leucophaeata and a marine mussel, Mytilus edulis. The mussels were subjected to continuous or intermittent (4 h chlorination followed by 4 h no chlorination) chlorination at concentrations varying from 1 to 3 mg l(-1) and their responses (lethal and sublethal) were compared to those of control mussels. In addition, shell valve activity of mussels was monitored using a Mussel-monitor. Data clearly indicate that mussels shut their valves as soon as chlorine is detected in the environment and open only after chlorine dosing is stopped. However, under continuous chlorination mussels are constrained to keep the shell valves shut continuously. The mussels subjected to continuous chlorination at 1 mg l(-1) showed 100% mortality after 588 h (D. polymorpha), 966 h (Mytilus edulis) and 1104 h (Mytilopsis leucophaeata), while those subjected to intermittent chlorination at 1 mg l(-1) showed very little or no mortality during the same periods. Filtration rate, foot activity index and shell valve movement of D. polymorpha, Mytilopsis leucophaeata and Mytilus edulis decreased more than 90% at 1 mg l(-1) chlorine residual when compared to control. However, mussels subjected to intermittent chlorination showed a similar reduction (about 90%) in filtration rate, foot activity index and shell valve movement during chlorination and 3% during breaks in chlorination. The data indicate that intermittent chlorination between 1 and 3 mg l(-1) applied at 4 h on and 4 h off cycle is unlikely to control biofouling if mussels are the dominant fouling organisms.     

Impacts of climate change on urban drainage systems – a case study in Fredrikstad,Norway

Norway has frequently encountered flood damage in urban areas during recent years. In this paper the authors, taking Veumdalen catchment in Fredrikstad as an example, simulated the possible consequences in the sewer system, in the present, predicted and artificial climate scenarios. Indicators that describe (1) surface flooding, (2) surcharging sewers, (3) basement flooding and (4) combined sewer overflow (CSO) are defined to represent the adverse effects of climate change. It is concluded from the annual-based simulation that the total volume of water spilling from the flooding manholes will increase 2–4-times the increase in precipitation, and the total CSO will increase 1.5–3-times as much as the increase in precipitation. The simulation results also show that the number of flooding manholes and number of surcharging sewers may change dramatically and irregularly with a slight change of precipitation, and vary with events and durations.     

Work–life fit: identification of demand and resource typologies within a systems framework*

Work–life fit occurs when people have the resources required to meet demands such that role performance (both at work and in non-work life domains) is effective. Interviews were conducted with 59 construction workers based in Melbourne, Australia to explore how demands and resources were experienced. Using a systems framework, data were analysed using thematic analysis. Results identified two demand typologies associated with demand-to-demand interaction. Demands operating as ‘influencers’ have a major impact on the conditions of the interdependent demand, while demands operating as ‘creators’ generate a new demand and shape the conditions of that demand. One resource typology related to resource–demand interaction was identified. ‘Enabling resources’ enable an individual to manage multiple demands across multiple domains, and may also enable an individual to manage multiple demands within a single domain. A new conceptual contribution is made to an area in which theory is under-developed, by adopting a systems approach to understanding the dynamic interactions between demands and resources. A lack of fit is damaging for the individual; therefore, it is useful to know that demands and resources are interdependent and these interdependencies will vary according to individuals. Using a systems approach to understanding demands and resources will be helpful to organizations seeking to support workers to achieve optimal work–life fit.