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ABSTRACT: Recent interest in applications of games and gaming methods has stimulated discussion of their use in engineering systems research. Simulation games or gaming simulations are interactive environments which simultaneously model a technical system through simulation and a social system with role‐play participants. Their boundary‐spanning nature aligns with challenges in engineering systems to consider both technical and social factors in design. This paper outlines a class of gaming methods for research in engineering systems. Key contributions synthesize diverse bodies of literature to classify gaming applications as generating generalizable and contextual knowledge to benefit participants and principals, identify intellectual foundations in related social sciences, and describe the dual purpose of games as a research method for analytical or design science objectives. Conclusions highlight opportunities and challenges for gaming research methods to accommodate social science research in design‐centric activities. [ABSTRACT FROM AUTHOR]

In developed countries, expansion of communication technology has resulted in continual increase in the construction of data centers with high-density cooling loads. Throughout a year, IT equipment installed in a data center generates large and constant cooling load. As a result, data centers may be consuming an ever-growing amount of energy. The cooling system utilizing the energy of outside air is applied universally to reduce data center energy consumption. The application of the cooling system to the outdoor air cooling system of a data center considers that temperature efficiency and ventilation performance vary depending on the type of ventilation system. The displacement and mixed ventilation method can be applied generally to a data center. The efficiency of a ventilation system depends on inside temperature or contaminant concentrations in room and outlets. This study thus aims to evaluate the ventilation performance that varies according to type of ventilation system installed in the data center. Ventilation efficiency is assessed by applying the concept of total air age and considers the fresh air ratio and age of return air. Further, temperature efficiency gained by utilizing temperature difference is used to assess causes for changes in ventilation performance. [ABSTRACT FROM AUTHOR]

The attachment of microbial biomass on solid surfaces is a universal phenomenon that occurs in natural and engineering systems and is responsible for various types of biofouling. Biological fouling, also referred to as biofouling, remains one of the most critical problems toward the durable application of materials. The eradication of this problem using sustainable and environmentally friendly techniques is still of critical importance and is therefore receiving significant interest from researchers worldwide. The authors start with a definition of processes that lead to biofouling and their relevance to various industrial applications. The most relevant findings from past research are presented and particular emphasis is focused on present research, where recent developments in surface modification receive specific attention. [ABSTRACT FROM PUBLISHER]

With a great capability of dealing with epistemic uncertainty, evidence theory has been utilised to conduct reliability analysis for engineering systems recently. Unfortunately, the discontinuous nature of uncertainty quantification using evidence theory incurs a huge computational cost. This paper proposes an efficient method to improve the computational efficiency of evidence theory for reliability analysis. In this method, evidence variables are transformed into random variables. Support vector regression is used to construct the approximation model of the limit-state function. The most probable point (MPP) of the approximate reliability problem with only random variables is searched out. Based on the MPP, the most probable focal element (MPFE) of the original problem with evidence variables is identified. According to the MPFE and the monotonicity of the limit-state function, contributions of some focal elements to belief and plausibility in evidence theory can be judged directly. Hence, the number of focal elements involved in the calculation of extreme values of the limit-state function is reduced. Four numerical examples are utilised to test the performance of the proposed method. Results indicate that the proposed method can reduce the computational cost on reliability analysis under epistemic uncertainty while ensuring the high accuracy of reliability analysis results. [ABSTRACT FROM AUTHOR]

There are a significant number of methods and approaches in design theory to support designers of mechanical engineering systems in everyday challenges. The applicability of these methods and approaches to industry appears limited, since influences on the product design process are only accounted marginally. This article presents a model that is based on theoretical approaches but is focused on extending system boundaries to factor in the modern work environment of mechanical engineering designers. Three areas of operation highly relevant to the development of economic products are included in the model: the classification of products according to the designated market, the decision-making process and the creation sequence. The areas are interlinked and are described using common as well as novel methods and approaches. An example design process is used to apply and evaluate the model. [ABSTRACT FROM AUTHOR]

The possibility of the remote monitoring of the functional state of a human operator using data-measuring systems is estimated. The signs indicating the normal state of the human operator are indicated. [ABSTRACT FROM AUTHOR]

Small spacecraft can now perform trajectory maneuvers resulting in significant orbit changes that were once only feasible with larger spacecraft due to the development of miniaturized propulsion technology. This paper addresses the feasibility of using CubeSat Ambipolar Thruster, a large ΔT miniaturized propulsion system for constellation control, Earth escape, and planetary flybys, to enable Earth-escape maneuvers on a CubeSat form factor. Operational and trajectory variables include the power setting during thrust maneuvers, when to thrust, and the attitude control inputs. The dynamic energy available through the maneuvers, which is constrained by the power available from the sun depending on the orbit and is consumed in propulsion, is modeled as well as attitude control maneuvers and realistic battery degradation. To explore the design space of this capability, the sensitivity of solutions to spacecraft mass, fuel quantity, initial orbit, solar power collection, and battery size is demonstrated. Optimal orbit-raising techniques are compared and the optimal approach depending on the goals is discussed (i.e., minimize time, minimize fuel, minimize batteries, minimize propulsion system volume, and minimize accumulated radiation). The models and results presented lay the groundwork for future work in integrated vehicle and operational design optimization problems with both interplanetary and constellation architectures. [ABSTRACT FROM AUTHOR]

Robust design optimization (RDO) is a popular framework for addressing uncertainties in the design of engineering systems by considering different statistical measures, typically the mean and standard deviation of the system response. RDO can lead to a wide range of different candidate designs, establishing a different compromise between these competing objectives. This work introduces a new robustness measure, termed probability of dominance, for assessing the appropriateness of each candidate design. This measure is defined as the likelihood that a particular design will outperform the rival designs within a candidate set. Furthermore, a multi-stage implementation is introduced to facilitate increased versatility/confidence in the decision-making process by considering the comparison among smaller subsets within the initial larger set of candidate designs. For enhancing the robustness in these comparisons the impact of prediction errors, introduced to address potential differences between the real (i.e. as built) system and the numerical model adopted for it, is also addressed. This extends to proper modeling of the influence of the prediction error, including selection of its probability model, as well as evaluation of its impact on the probability of dominance and on the RDO formulation itself. Two illustrative examples are presented, the first considering the design of a tuned mass damper (TMD) for vibration mitigation of harmonic excitations and the second a topology optimization problem for minimum compliance. Extensive comparisons are presented in these two examples and the discussions demonstrate the power of the proposed approach for assessing the designs' robustness. [ABSTRACT FROM AUTHOR]

We propose a simple payoff-based learning rule that is completely decentralized and that leads to an efficient configuration of actions in any n-person finite strategic-form game with generic payoffs. The algorithm follows the theme of exploration versus exploitation and is hence stochastic in nature. We prove that if all agents adhere to this algorithm, then the agents will select the action profile that maximizes the sum of the agents' payoffs a high percentage of time. The algorithm requires no communication. Agents respond solely to changes in their own realized payoffs, which are affected by the actions of other agents in the system in ways that they do not necessarily understand. The method can be applied to the optimization of complex systems with many distributed components, such as the routing of information in networks and the design and control of wind farms. The proof of the proposed learning algorithm relies on the theory of large deviations for perturbed Markov chains. [ABSTRACT FROM AUTHOR]

This paper presents a method for incorporating the expressivity of human performance into real-time computational audio generation for games and other immersive environments. In film, Foley artistry is widely recognised to enrich the viewer's experience, but the creativity of the Foley artist cannot be easily transferred to interactive environments where sound cannot be recorded in advance. We present new methods for human performers to control computational audio models, using a model of a squeaky door as a case study. We focus on the process of selecting control parameters and on the mapping layer between gesture and sound, referring to results from a separate user evaluation study. By recording high-level control parameters rather than audio samples, performances can be later varied to suit the details of the interactive environment. [ABSTRACT FROM AUTHOR]

Dynamic engineering systems are playing an increasingly important role in society, especially as active and autonomous dynamic systems become more mature and prevalent across a variety of domains. Successful design of complex dynamic systems requires multidisciplinary analysis and design techniques. While multidisciplinary design optimization has been used successfully for the development of many dynamic systems, the established multidisciplinary design optimization formulations were developed around fundamentally static system models. General multidisciplinary design optimization approaches that address the specific needs of dynamic system design are still lacking. In this article, the use of multidisciplinary design optimization for dynamic system design is reviewed, associated challenges are identified, related efforts such as optimal control are discussed, and a vision for fully integrated design approaches is presented. Finally, a set of exciting new directions that provide an opportunity for fundamental work in multidisciplinary design optimization is laid out. [ABSTRACT FROM AUTHOR]

Control of systems that have had their passive input-output map partially violated is the motivation of this study. The hybrid passivity/finite-gain systems framework is specifically well suited to systems that have experienced a passivity violation. The focus of this study is the extension and application of the hybrid passivity/finite-gain systems framework to a multi-input multi-output (MIMO) control problem. Calculation of the hybrid passivity/finite-gain parameters in a linear time-invariant (LTI) MIMO context is considered. Additionally, we show that a set of hybrid very strictly passive/finite-gain (VSP/finitegain) controllers gain-scheduled in a particular way also possesses hybrid VSP/finite-gain properties. To synthesise hybrid VSP/finite-gain controllers a frequency-weighted optimal control scheme is used to parameterise controllers that are then constrained and optimised within a numerical optimisation framework. The theoretical contributions of this work are validated experimentally using a two-link flexible manipulator apparatus. Results highlight the utility of the hybrid passivity/finite-gain framework, the scheduling scheme and controller design method. [ABSTRACT FROM AUTHOR]

This paper surveys the current state of research related to the modeling and prediction of failures of engineering systems. It is argued that while greater understanding of the physics of failure has led to significant progress at the component level, there are significant challenges remaining at the system level. System reliability, a field of applied mathematics that addresses the latter challenges, is at a juncture where fundamental changes are likely. On the one hand, the traditional part of the field entered a phase of diminishing returns, largely having followed the trajectory of the Cold- War era technology development: golden years of rapid growth in the 1950s and 1960s, followed by maturation and slowing down in the ensuing decades. On the other hand, the convergence of several technologies related to data collection and processing, combinedwith important changes in engineering business and government priorities, has created the potential for a perfect storm that can revive and fundamentally transform the field; however, for this transformation to occur, some serious obstacles need to be overcome. The paper examines these obstacles along with several key areas of research that can provide enabling tools for this transformation. [ABSTRACT FROM AUTHOR]

As an important tool for performance assessment in multi-state systems, the universal generating function approach is introduced and developed aiming at strength reliability analysis of structural systems. Static reliability models of statically determinate and statically indeterminate systems are built by constructing special generating functions, which are used to describe probability distributions of the resistance and the load. Composition operators and performance structure functions thereof are defined to composite different universal generating functions. When composition operators are executed, computational costs can be reduced by means of collecting like terms. The results of theoretical analysis and numerical simulation show that the generating function approach can be widely used for probability modeling of large complex systems with the failure dependence. [ABSTRACT FROM AUTHOR]

Light-weight flexible arms will most likely constitute the next generation robots due to their large payload carrying capacities at high speeds and less power demand. Control problem of robots with flexible members is more complex compared to rigid robots due to vibrations during the motion. This paper presents the optimization technique inspired by social behavior of bird flocking to optimize hybrid Fuzzy Precompensated Proportional – Derivative (PD) controller in trajectory control of two link rigid-flexible manipulator. Numerical simulation using the dynamic model of two link rigid-flexible manipulator shows the effectiveness of the approach in trajectory tracking problems and the use of fuzzy precompensation has superior performance in terms of improvement in transient and steady state response, robustness to variations in loading conditions and ease to use in practice. Comparative evaluation with respect to genetic algorithm based optimization is presented to validate the controller design. The results presented emphasize that a satisfactory tracking precision could be achieved using hybrid Fuzzy Precompensated Proportional – Derivative controller with particle swarm optimization. [ABSTRACT FROM AUTHOR]

In this paper, we focus on two-level linear programming problems involving random variable coefficients in objective functions and constraints. According to the concept of chance constrained programming, the two-level stochastic linear programming problems are transformed into deterministic ones through the expectation optimization model and the variance minimization model. After introducing fuzzy goals for objective functions, interactive fuzzy programming to derive a satisfactory solution for decision makers is presented as a fusion of stochastic approach and fuzzy one. An illustrative numerical example is provided to demonstrate the feasibility of the proposed method. [ABSTRACT FROM AUTHOR]

An important inspection task in the automated assembly of printed circuit boards (PCBs) is that of detecting if all components have been placed correctly on the board. This paper describes a constrained evolutionary search based inspection technique for simultaneously detecting multiple component objects in a source image. The approach has the advantage that it does not rely on image alignment (registration) as do conventional optical inspection methods such as image subtraction. It is a template based search method which achieves speed and quality requirements by making use of an evolutionary algorithm and a simultaneous search for multiple objects in a source image using a generalised template. The generalised template matching method defines a template model that takes into account the statistical variations between the grey-level appearances of components. The evolutionary search for specific components is constrained to Canny edges making this a fast method for locating multiple targets. Results are presented for locating multiple surface mount resistors on a PCB so that missing components can be reported. [ABSTRACT FROM AUTHOR]

This paper proposes an immunity-based system for detecting masqueraders in UNIX-like systems. The system is based on the specificity and diversity of the immune system. In other words, the immunity-based system has a user-specific agent for every user, and makes use of multiple profiles, not a single profile. The use of multiple profiles can lead to an improvement in masquerader detection accuracy. In fact, the immunity-based method outperforms other two methods which was the best detection performance in the previous works. In addition, we propose an evaluation framework for the immunity-based masquerader detection system. The evaluation framework is capable of evaluating the differences in detection accuracy between internal and external masqueraders. [ABSTRACT FROM AUTHOR]

Considering the disadvantages of using subjective weights in the former studies for the risk assessment of the flood control engineering system, the variable fuzzy pattern recognition model based on the combination of the subjective and objective weights is developed. Projection pursuit (PP) method is employed, to calculate the objective weights in the model, and the information entropy is considered in the PP object function. The model's reliability is improved due to using variable fuzzy sets model for the projection value calculation. The combined weights formulas are obtained based on the minimum discriminating information principle. The case shows that subjective and objective weights can be taken into account comprehensively in the presented model, and the identification result is stable and valid. [ABSTRACT FROM AUTHOR]

Testing techniques of dynamically substructured systems dissects an entire engineering system into parts. Components can be tested via numerical simulation or physical experiments and run synchronously. Additional actuator systems, which interface numerical and physical parts, are required within the physical substructure. A high-quality controller, which is designed to cancel unwanted dynamics introduced by the actuators, is important in order to synchronize the numerical and physical outputs and ensure successful tests. An adaptive forward prediction (AFP) algorithm based on delay compensation concepts has been proposed to deal with substructuring control issues. Although the settling performance and numerical conditions of the AFP controller are improved using new direct-compensation and singular value decomposition methods, the experimental results show that a linear dynamics-based controller still outperforms the AFP controller. Based on experimental observations, the least-squares fitting technique, effectiveness of the AFP compensation and differences between delay and ordinary differential equations are discussed herein, in order to reflect the fundamental issues of actuator modelling in relevant literature and, more specifically, to show that the actuator and numerical substructure are heterogeneous dynamic components and should not be collectively modelled as a homogeneous delay differential equation. [ABSTRACT FROM AUTHOR]