Complex Systems Design & Management Asia

Energy consumption is one of the primary non-functional properties to be addressed early in software system development. Model-based analysis methods are introduced in order to supplement the current practice of runtime profiler techniques. In the present paper, the energy consumption analysis is classified as a duration bounded cost constraint problem. Specifically, behavioral contracts based on Power Consumption Automata and properties written in terms of weighted linear temporal logic with freeze quantifiers are proposed. In addition, the problem is solved by model-checking of such logic formulas with respect to the automaton.

In this paper, we propose UNISENSE, a unified and sustainable sensing and transport architecture for large scale and heterogeneous sensor networks. The proposed architecture incorporates seven principal components, namely, application profiling, node architecture, intelligent network design, network management, deep sensing, generalized participatory sensing, and security.We describe the design and implementation for each component. We also present the deployment and performance of the UNISENSE architecture in four practical applications.

Safety and security are two key properties of Cyber-Physical Systems (CPS). Safety is aimed at protecting the systems from accidental failures in order to avoid hazards, while security is focused on protecting the systems from intentional attacks. They share identical goals - protecting CPS from failing. When aligned within a CPS, safety and security work well together in providing a solid foundation of an invincible CPS, while weak alignment may produce inefficient development and partially-protected systems. The need of such alignment has been recognized by the research community, the industry, as well as the International Society of Automation (ISA), which identified a need of alignment between safety and security standards ISA84 (IEC 61511) and ISA99 (IEC 62443). We propose an approach for aligning CPS safety and security at early development phases by synchronizing safety and security lifecycles based on ISA84 and ISA99 standards. The alignment is achieved by merging safety and security lifecycle phases, and developing an unified model - Failure-Attack-CounTermeasure (FACT) Graph. The FACT graph incorporates safety artefacts (fault trees and safety countermeasures) and security artefacts (attack trees and security countermeasures), and can be used during safety and security alignment analysis, as well as in later CPS development and operation phases, such as verification, validation, monitoring, and periodic safety and security assessment.

Vehicle fleet modeling is a useful tool to analyze the dynamics of motor vehicles and their environmental impact at a macroscopic level, and has been applied in the USA and Europe. In this article, a road fleet model is constructed for the city-state Singapore. Policies that control vehicle ownership and congestion road pricing employed since 1998 differentiate Singapore’s vehicle market from other markets, making it a particularly interesting case to investigate. The fleet model is constructed using spreadsheets that track vehicle age, vehicle population, vehicle kilometers travelled, fleet fuel use and greenhouse gas (GHG) emissions. The authors hope that the model can be used as a tool to help stakeholders assess the social and environmental impact of relevant policies like capping vehicle growth, scrappage policy, reducing vehicle mileage and adopting green vehicles.

This paper presents a flexibility analysis as a practical procedure to evaluate large-scale capital-intensive projects considering market uncertainty. It considers the combined effects of the time value of money, economies of scale, and learning, and demonstrates the additional benefits stemming from considerations of uncertainty and flexibility in the early stages of design and project evaluation. This study focuses on the long-term deployment of liquefied natural gas (LNG) technology in a target market to supply the transportation sectors. Two design alternatives are considered: 1) fixed design, a big centralized production facility; 2) flexible modular designs, either using phasing approach at the big plant site or the same flexible approach with an option to move modular plants at distance. To compare the design alternatives, a structured flexibility methodology is applied based on several economic lifecycle performance indicators (e.g. Net Present Value, Initial CAPEX, etc.). Results indicate that a flexible modular deployment strategy improves the economic performance as compared to optimum fixed designs. They also indicate that factoring flexibility to locate modules at a distance further improves system performance. Such improvement enhances as learning rate increases. Overall, the study shows that flexibility in engineering design has multiple, supporting advantages due to uncertainty, location and learning.

With the Singapore Armed Forces (SAF) building up network-centric warfare capabilities, the reliance on the multiplier effects from inter-connectivity and collaborative operations among forces becomes increasingly critical. Availability has been applied typically at the system level, as a means to analyse the readiness and logistics effectiveness of the fighting force. Such a standalone system level Measure of Effectiveness (MOE) is no longer adequate to capture complex interdependency and ensure the readiness of networked systems in a holistic manner.

Today, the Optimised Decisions in Networks (ODIN) tool equips DSTA and the SAF with the ability to quantify networked system architecture and provide the means to identify critical links/bottle-necks that enhance design decision of the architecture. It provides us the means to examine network robustness and survivability under complex threat environment. ODIN seeks to perform resource (spares, manpower, equipment) optimisation at the network or System-of-Systems (SoS) level to ensure they are considered holistically to meet stringent demands. This paper aims to describe the methodologies and capabilities of ODIN. Such Systems Engineering approach could be similarly applied to the design of our smart cities to provide resiliency in design and best allocation of resource to meet the inter-dependencies and high degree of connectivity needed for utilities, transport and communications of today cities.

There is a wide array of public transportation in Singapore. Travelling from one part of Singapore to another is a breeze thanks to a highly penetrative public transport system. The three main modes of public transport in Singapore are the Mass Rapid Transit (MRT), buses and taxis. Buses are, by far, the most common form of public transportation in Singapore, followed by the MRT and taxis respectively. Public buses serve almost every part of Singapore, making it the most extensive form of public transportation, while the MRT provides speed and efficiency, especially during peak hours.

This case examines the public transportation of Singapore from a large scale system engineering perspective and aim to help the reader to understand the complexities of such a system: its mission, vision and goals, boundaries, and promoting public transport through a systems approach.

Technical products are facing different changes during their lifecycle. These changes can have drastic impacts to the product, either towards its structure or the effort for the implementation. If platform elements used in various products within a product family, the change impact can be capital. Based on existing methods, we developed an approach to propagate changes, triggered by a specific cause, in technical systems. The approach consists of matrix-based methods and allows the propagation via different domains, for example components, functions and variation attributes. Change causes can be linked more easily to the product architecture and the change impact can be traced via different relevant product domains. The approach is illustrated by an industrial case study shown in this contribution.

The long lifetime of technological systems increases the importance of understanding those technologies that are experiencing rapid improvements. Ideally we would like to design our systems around these technologies so that we can benefit from the future benefits that these rapid improvements in component performance and cost can provide at a system level. This paper provides data on technologies that are experiencing rapid improvements and it uses transportation systems to demonstrate the impact of rates of improvement on system design issues.