Adopting HLA standard for interdependency study

In recent decades, modern Critical Infrastructure (CI) has become increasingly automated and interlinked as more and more resources and information are required to maintain its day-to-day operation. A system failure, or even just a service debilitation, of any CI may have significant adverse effects on other infrastructures it is connected/interconnected with. It is vital to study the interdependencies within and between CIs and provide advanced modeling and simulation techniques in order to prevent or at least minimize these adverse effects. The key limitation of traditional mathematical models such as complex network theory is their lacking the capabilities of providing sufficient insights into interrelationships between CIs due to the complexities of these systems. A comprehensive method, a hybrid approach combining various modeling/simulation techniques in a distributed simulation environment, is presented in this paper. High Level Architecture (HLA) is an open standard (IEEE standard 1516) supporting simulations composed of different simulation components, which can be regarded as the framework for implementing such a hybrid approach. The concept of adopting HLA standard for the interdependency study is still under discussion by many researchers. Whether or not this HLA standard, or even the distributed simulation environment, is able to meet desired model/simulation requirements needs to be carefully examined.This paper presents the results from our experimental test-bed, which recreates the architecture of a typical Electricity Power Supply System (EPSS) with its own Supervisory Control and Data Acquisition (SCADA) system, for the purpose of investigating the capabilities of the HLA technique as a standard to perform interdependency studies.     

Distributed simulation of virtual workshops for the multi-site scheduling feasibility evaluation

In this article, a distributed simulation tool for the feasibility evaluation of multi-site scheduling is proposed. The application areas concern supply chains (SCs) or networks of distributed workshops. The distributed simulation of workshops, called virtual workshops, generates various problems of causality and of tasks execution coordination. These problems are addressed in the proposed distributed architecture by the use of High Level Architecture protocol guaranteeing the synchronisation and the chronology of events occurring in the distributed simulations. An application to a simple case of the SC organising the flow between three workshops shows the effectiveness of the distributed simulation tool.     

Investigation into the use of solid nitrogen to create a “Thermal Battery” for cooling a portable high-temperature superconducting magnet

The design of a portable, “stand-alone” cooling system, for use with a high-temperature superconducting (HTS) magnet, is discussed. The HTS magnet is used to propel a magnetohydrodynamically powered model boat (approximately 120 cm × 60 cm). The aim of this investigation was to establish the suitability of solid nitrogen for use in the stand-alone cooling system, and determine the optimum method for exploiting its cooling power. It was found that obtaining good thermal contact between solid nitrogen and its container is very difficult if the nitrogen is frozen under vacuum, due to the formation of a thermal barrier between the nitrogen and its container. This problem is overcome if the nitrogen is frozen via conduction cooling from cold helium gas (at ∼4.2 K); and the design for a near isothermal “thermal battery” based on this principle is presented. This thermal battery has been constructed and integrated into the HTS magnet system onboard the model boat, and the results from the first trials of this system are presented here.     

Bridging the critical interface: Ambidextrous innovation for water provision in Nairobi's informal settlements

This article examines innovation activities in water infrastructure in Nairobi, Kenya. The focus is on efforts by Nairobi City Water and Sewerage Corporation (NCWSC) to provide water services to the inhabitants in the informal areas of the city using an automated vending machine, or Pre-Paid Dispenser (PPD). In this study, we investigate what happens when a regime actor like NCWSC tries to implement an ambidextrous (two-handed) strategy: managing the existing system according to conventional practice and at the same time innovate in new technical solutions and business models to cater for unconnected users.Besides presenting our results, our aim in this article is also to introduce a research strategy for innovation studies in infrastructural systems in low-income urban areas. Three interconnected parts stand out as our contribution:First, we present a novel conceptual framework, by adding ideas from innovation studies to the Large Technical Systems approach. We investigate how regime actors can innovate to provide water to unconnected users, without expanding the system in a traditional way.Second, we propose a novel method for analysing and understanding innovation on the margins of the infrastructural system, or in our terms, innovation in the critical interface. Central to our method is, through empirical observation, to identify misalignment between the innovation (PPD) and contextual factors at the local level, where the innovation is implemented (interface misalignment), and misalignment between the innovation and the existing water regime (internal misalignment). We use a qualitative method and results forms as a basis for further research and starting point for regime actors in search of an improved ambidextrous strategy.Third, we analyse the innovation process per se. In the Nairobi case, we assess the ambidextrous innovation strategy, and claim that the PPD functions as an adapter in the critical interface, enabling the regime actors to operate in an environment of misalignment.     

Magnetic-field angle dependent critical current densities and flux pinning in commercial YBCO tapes at liquid nitrogen temperatures

The magnetic-field angle dependence of critical current densities J_c(H,θ) in commercial YBCO tapes grown by MOCVD and MOD was examined at liquid nitrogen temperatures. We first measured J_c(H,θ) in MOCVD-YBCO tapes at 70 and 77.3 K in fields up to 2 T using both transport and inductive (the third harmonic voltage) methods and compared the results. It was observed that, in low magnetic fields, the transport measurements gave higher J_c than the inductive ones; however, in high fields they agreed well, which is well explained by the effects of weak links due to low-angle grain boundaries. We then investigated J_c(H,θ) in MOCVD- and MOD-YBCO tapes at 77.3 K in fields up to 2 T. All the tapes exhibited peaks at H//ab in the shape of Mount Fuji, which shows that small random pinning plays a major role. However, an anisotropic scaling analysis showed that the flux pinning mechanisms in those tapes were different, resulting in distinctive angular behaviors of J_c(H,θ). It is suggested that the difference in the flux pinning mechanisms of the two types of tapes came from the different sizes of point defects originating from the growing processes.     

Multiaxial fatigue damage parameter and life prediction for medium-carbon steel based on the critical plane approach

The tension–torsion fatigue characteristics were investigated under proportional and non-proportional loading in this paper. The fatigue cracks on the surface of multiaxial fatigue specimens were observed and analyzed by a scan electron microscope. On the basis of the investigation on the Kindil–Brown–Miller and Fatemi–Socie’s critical plane approaches, a shear strain based multiaxial fatigue damage parameter was proposed by von Mises criterion based on combining the maximum shear strain and the normal strain excursion between adjacent turning points of the maximum shear strain on the critical plane. The proposed multiaxial fatigue damage parameter does not include the weight constants. According to the proposed multiaxial fatigue damage parameter, the multiaxial fatigue life prediction model was established with the Coffin–Manson equation, which is used to predict the multiaxial fatigue life of medium-carbon steel. The results showed that the proposed multiaxial fatigue damage parameter could be used under either multiaxial proportional or non-proportional loading.     

分布仿真系统HLA联邦快速开发包的设计与实现

为提高高层体系结构(HLA)联邦开发的快捷性、易用性、可重用性及节约成本,对其运行支撑环境(RTI)接口进行了封装,结合数据公布订购自定义配置文件和MAP容器,设计并实现了封装的仿真接口包(SPI).首先,给出了SPI包的框架设计、功能分解结构、时序逻辑及函数接口定义,然后设计了仿真应用数据类的具体规范、联邦可执行文件XML和邦元公布订购数据的初始化配置文件,阐述了基于SPI的联邦快速开发步骤,最后用一个简单实例验证SPI.实验表明:相比现有的联邦编程开发软件,SPI简单高效,用户可自行设计并轻松上手,降低了开发成本,满足了特定的仿真需求.     

A framework for determining MIMO process parameters by a neuro-DM&ACO approach

A framework combining artificial neural network (ANN) modelling technique, data mining and ant colony optimisation (ACO) algorithm is proposed for determining multiple-input multiple-output (MIMO) process parameters from the initial chemical-mechanical planarisation (CMP) processes used in semiconductor manufacturing. Owing to the invisibility of the ANN in the solution procedures, the decision tree approach of data mining is adopted to provide the necessary information for a real-valued ACO. The simulation result demonstrates that the proposed method can be an efficient tool for selecting properly defined parameter combination with the CMP process.     

A critical review of ultra-accelerated tests for alkali-silica reactivity

A large number of ultra-accelerated test procedures, for determining the potential alkali reactivity of aggregates, have been developed, particularly in the past 15 years. An ultra-accelerated test method is defined as one which yields results within a few days or, at most, a few weeks. A number of ultra-accelerated test methods have been adopted as ‘standard tests’, but few have been adequately evaluated. The rapid globalization of the construction industry will require the harmonization of National Standard Test Methods. The major requirement of ultra-accelerated test methods is that they should correctly predict the potential reactivity of aggregates in greater than 95% of the cases. Due to the complexity and variability in the composition and grain size of aggregates, it is improbable that a single test method will be developed which would be appropriate for evaluating all types of aggregates. Another major requirement for ultra-accelerated test methods is that the interlaboratory coefficient of variation should be low, preferably less than 12%. At present, only the NBRI accelerated mortar bar method has been subject to adequate inter-laboratory evaluation. However, a more limited inter-laboratory investigation showed that the autoclave mortar bar test also shows considerable potential, as a satisfactory ultra-accelerated test method. Further refinement of the NBRI and autoclave methods is required to improve their performance with a wide variety of aggregates.     

A fuzzy ANP-based approach to R&D project selection: A case study

Research and development (R&D) project selection is a complex decision-making process. It involves a search of the environment of opportunities, the generation of project options, and the evaluation by different stakeholders of multiple attributes, both qualitative and quantitative. Qualitative attributes are often accompanied by certain ambiguities and vagueness because of the dissimilar perceptions of organizational goals among pluralistic stakeholders, bureaucracy and the functional specialization of organizational members. Such differences in perceptions often hinder the attainment of consensus and coordination. Therefore, failures are frequent in R&D investment planning. To perceive the preferences of the various stakeholders and to map them into an analytical decision-making framework are challenging tasks. Further, risks and uncertainties are also associated with the investments and returns of R&D projects. This paper illustrates an application of fuzzy ANP (analytic network process) along with fuzzy cost analysis in selecting R&D projects. Fuzzy set theory is incorporated to overcome the vagueness in the preferences. The method adopted uses triangular fuzzy numbers for pair-wise comparison and applies extent analysis followed by defuzzification to determine the weights for various attributes.     

Determination of the critical conditions for the initiation of dynamic recrystallization in boron microalloyed steels

From the present research, the critical conditions associated with the onset of dynamic recrystallization (DRX) of hot deformed boron microalloyed steels were precisely determined based on changes in the strain hardening rate (θ) as a function of the flow stress. For this purpose, a low carbon steel microalloyed with four different amounts of boron (29, 49, 62 and 105 ppm) was deformed by uniaxial hot-compression tests at high temperature (950, 1000, 1050 and 1100 °C) and constant true strain rate (10⁻³, 10⁻² and 10⁻¹ s⁻¹). Results indicate that the critical conditions for the initiation of dynamic recrystallization depend on the temperature and strain rate. In addition, both critical stress σ_c, and critical strain ?_c, were noticed to decrease as boron content increased. Such a behavior is attributed to a solute drag effect by boron atoms on the austenitic grain boundaries and also to a solid solution softening effect. The critical ratios σ_c/σ_p and ?_c/?_p for all boron microalloyed steels remain fairly constant (≈0.82 and ≈0.53, respectively), such values are in agreement with those commonly reported for Al-killed, C-Mn, Nb, Nb-Ti, high carbon and stainless steels.     

Sensitivity analyses of FORM‐based and DRM‐based performance measure approach (PMA) for reliability‐based design optimization (RBDO)

In gradient‐based design optimization, the sensitivities of the constraint with respect to the design variables are required. In reliability‐based design optimization (RBDO), the probabilistic constraint is evaluated at the most probable point (MPP), and thus the sensitivities of the probabilistic constraints at MPP are required. This paper presents the rigorous analytic derivation of the sensitivities of the probabilistic constraint at MPP for both first‐order reliability method (FORM)‐based performance measure approach (PMA) and dimension reduction method (DRM)‐based PMA. Numerical examples are used to demonstrate that the analytic sensitivities agree very well with the sensitivities obtained from the finite difference method (FDM). However, as the sensitivity calculation at the true DRM‐based MPP requires the second‐order derivatives and additional MPP search, the sensitivity derivation at the approximated DRM‐based MPP, which does not require the second‐order derivatives and additional MPP search to find the DRM‐based MPP, is proposed in this paper. A convergence study illustrates that the sensitivity at the approximated DRM‐based MPP converges to the sensitivity at the true DRM‐based MPP as the design approaches the optimum design. Hence, the sensitivity at the approximated DRM‐based MPP is proposed to be used for the DRM‐based RBDO to enhance the efficiency of the optimization. Copyright © 2009 John Wiley & Sons, Ltd.     

Efficient texture analysis for industrial inspection

This paper describes a convolution-based approach to the analysis of images containing few texture classes. Segmentation of foreground and background textures, or detection of boundaries between similarly textured objects, is demonstrated. The application to industrial inspection applications is demonstrated. Near frame-rate performance on low-cost hardware is possible, since only convolution with small kernels is used. A new algorithm to optimize convolution kernels for the required texture analysis task is presented. A key feature of the paper is the industrial readiness of the techniques described.     

Assessing impacts on people's relationships to place and community in health impact assessment: an anthropological approach

This paper explores a way in which health impact assessment (HIA) practitioners can improve their evaluation of the effects of infrastructure developments on people's intangible connections and emotional attachments to places and communities, and their health impacts. This assessment poses conceptual and methodological challenges. It is argued that social anthropology and the social sciences offer HIA a conceptual vocabulary and a methodology for exploring these relationships. These relationships are defined then positioned in HIA as an outcome of the health determinant, social capital. The paper offers a critique of their treatment in an HIA case study from the United Kingdom. Its shortcomings are used to propose a predominantly qualitative, anthropological methodology. The overall approach offers benefits. Practitioners gain clarification, new tools, a more holistic HIA, and links between these relationships, well-being, and sustainability and resilience. Developers are shown how to sensitise their approach, potentially enhancing community support.     

A practical vapor pressure equation for helium-3 from 0.01 K to the critical point

A saturation vapor pressure equation, p(T), is an essential component in the ³He state equation currently under development. The state equation is valid over the range 0.01-20 K with pressures from 0 to the melting pressure or 15 MPa. The vapor pressure equation consequently must be valid from 0.01 K to the critical temperature. This paper surveys available ³He critical temperature and pressure measurements, leading to new recommended critical values of 3.3157 K and 114603.91 Pa. The ITS-90 temperature scale is defined by the ³He vapor pressure from 0.65 to 3.2 K. A new vapor pressure equation is developed for the interval from the upper end of the T₉₀ scale to this newly defined critical point, employing a mathematical form in which the second derivative d²p/dT² diverges in agreement with scaling laws at the critical point. Below 0.65 K, an empirical vapor pressure expression is adopted, consistent with a theoretical expression valid in the limit T → 0. These two new components are fitted to be piecewise continuous with the EPT-76 p(T) scale rather than the ITS-90 T(p) scale between 0.65 and 3.2 K. Probable deviations between this vapor pressure scale and PLTS-2000 melting pressure-temperature scale are recognized, but not reconciled.     

POD–ISAT: An efficient POD‐based surrogate approach with adaptive tabulation and fidelity regions for parametrized steady‐state PDE discrete solutions

A combination of proper orthogonal decomposition (POD) analysis and in situ adaptive tabulation (ISAT) is proposed for the representation of parameter‐dependent solutions of coupled partial differential equation problems. POD is used for the low‐order representation of the spatial fields and ISAT for the local representation of the solution in the design parameter space. The accuracy of the method is easily controlled by free threshold parameters that can be adjusted according to user needs. The method is tested on a coupled fluid‐thermal problem: the design of a simplified aircraft air control system. It is successfully compared with the standard POD; although the POD is inaccurate in certain areas of the design parameters space, the POD–ISAT method achieves accuracy thanks to trust regions based on residuals of the fluid‐thermal problem. The presented POD–ISAT approach provides flexibility, robustness and tunable accuracy to represent solutions of parametrized partial differential equations.Copyright © 2013 John Wiley & Sons, Ltd.     

A practical density equation for saturated vapor of helium-3 from 0.01 K to the critical point

Based on the ideal gas state equation and the saturated vapor pressure equation of helium-3, a saturated vapor density equation is proposed, which can be applied for calculating the saturated vapor density of helium-3 from 0.01 K to the critical temperature. Above 1.4 K, the average deviation between the results by this equation and experimental data is about 0.66% and the maximum is 2%. Below 1.4 K, the results of this work show a comfortable agreement with those by virial state equation (the deviations are generally within 0.1%). Based on this new vapor density equation, the compressibility factor of saturated vapor is determined and the vaporization heat is calculated.     

An enhanced approach for the progressive mean control charts

To maintain and improve the quality of the processes, control charts play an important role for reduction of variation. To detect large shifts in the process parameters, Shewhart control charts are commonly applied but for small shifts, exponentially weighted moving averages (EWMA), cumulative sum (CUSUM), double exponentially weighted moving average (DEWMA), double CUSUM, moving average (MA), double moving average (DMA), and progressive mean (PM) control charts, are used. This study proposes double progressive mean (DPM) and optimal DPM control charts to enhance the performance of the PM chart. As the proposed DPM control charts use information sequentially, hence their performance is compared with natural competitors EWMA, CUSUM, DEWMA, double CUSUM, MA, DMA, and PM control charts. Run length and its different properties are evaluated to compare the performance of the proposed charts and counterparts. Results reveal that proposed optimal DPM outperforms the other charts. An example related to voltage on fixed capacitance level is also provided to illustrate the proposed charts.     

Investigation of interfacial segregation at antiphase boundaries in a ternary alloy 84.8Ni–12.8Al–2.4Ta

A thin interphase layer (4 nm) between the merging γ′ precipitates in a chosen model alloy 84.8Ni–12.8Al–2.4Ta was investigated. It is demonstrated that interfacial segregation may occur at an antiphase boundary (APB) interface between the thin layer and one of the merging γ′ precipitates. The magnitude of the lattice displacement (about 1/10[010]) caused by interfacial segregation has been measured both by comparing experimental images with computer simulations, and from high resolution electron microscopy (HREM) fringe spacings using linear regressional analysis. These measurements show a consistent lattice spacing reduction across the APB. Image simulations also highlight the way that the contrast of the bounding partial dislocation affects the APB interface image and can be used to obtain the lattice shift across the interface when the segregation effects on -fringe contrast are significant.