Roshanak Nilchiani

Measuring the Resilience of the Trans-Oceanic Telecommunication Cable System

Resilience is the ability of the system to both absorb shock as well as to recover rapidly from a disruption so that it can return back to its original service delivery levels or close to it. The trans-oceanic telecommunication fiber-optics cable network that serves as the backbone of the internet is a particularly critical infrastructure system that is vulnerable to both natural and man-made disasters. In this paper, we propose a model to measure the base resiliency of this network, and explore the node to node and the overall resiliency of the network using existing data for demand, capacity and flow information. The submarine cable system is represented by a network model to which hypothetical disruptions can be introduced. The base resiliency of the system can be measured as the ratio of the value delivery of the system after a disruption to the value deliver of the system before a disruption. We further demonstrate how the resiliency of the trans-oceanic telecommunication cable infrastructure is enhanced through vulnerability reduction.

A framework for assessing resiliency of maritime transportation systems

Resiliency can be defined as the ability of the system to bounce back after a shock and return to its normal value delivery levels. In maritime transportation systems (MTS), manmade and natural disruptions reduce the capacity of ports to send and receive goods, which can result in significant negative socio-economic impacts. Implementing resiliency in these systems improves their ability to cope with disruptions hence minimising losses. This paper proposes several schemes that improve resiliency by reducing the systems vulnerability and increasing its adaptive capacity. The impact of the schemes on the systems resiliency metrics are evaluated by applying the methodology of the Networked Infrastructure Resiliency Assessment framework. The framework consists of three stages in which a network model is extracted from the physical network, the resiliency metrics are identified and the system is modelled using network optimisation techniques and a system dynamics model. The disruptions are modelled by reducing the capacity of a port to send and receive goods. Three MTS resiliency metrics are identified, namely tonnage resiliency, time resiliency and cost resiliency. The presented case study assesses resiliency schemes, such as Diversity, Collaboration and Resource Allocation on the three resiliency metrics.

Measuring the resilience of the global internet infrastructure system

Resilience is the ability of the system to both absorb shock as well to recover rapidly from a disruption so that it can return back to its original service delivery levels or close to it. In the aftermath of 9/11 and Hurricane Katrina, there has been an increasing interest in infrastructure resilience. The global submarine fiber optics cable network that serves as the backbone of the internet is a particularly critical infrastructure system that is vulnerable to both natural and man-made disasters. In this paper, we propose a model to measure the base resiliency of this global network, and explore the node to node and global resiliency of the network using existing data demand, capacity and flow information. The base resiliency of the system can be measured as the value delivery of the system after a disruption to the value deliver of the system before a disruption. We further demonstrate how the resiliency of the global internet infrastructure is enhanced through reducing the network vulnerability and increasing its adaptive capacity.

Defining a Set of Metrics to Evaluate the Potential Disruptiveness of a Technology

Abstract: Disruptive technology can be defined as an emerging technology whose arrival in the marketplace signifies the eventual displacement of the dominant technology in that sector. Defining and assessing a set of key metrics for a disruptive technology at its early stages can substantially aid an enterprise to develop requirements, identify, and in turn increase the possibility of the successful launch of a disruptive technology. This article aims at defining a set of key metrics for evaluation of a possible disruptive technology. A case study is subsequently used for demonstrating the metrics identified. The article concludes with its relevance to the engineering management domain and directions for future research.

A Risk Management-based Decision Analysis Framework for resilience in Maritime Infrastructure and Transportation Systems

This research is an effort to develop a Risk Management-based Decision Analysis (RMDA) Framework based on the common fundamental elements that define the nature of resilience in Maritime Infrastructure and Transportation Systems (MITS). While developing a systematic process for making strategic and investment decisions, RMDA enables the decision-makers to identify, analyze, and prioritize risks involved in MITS operations; to define ways for risk mitigation, plan for contingencies, and devise mechanisms for continuously monitoring and controlling risk factors and threats to the system. Our suggested RMDA framework utilizes a Decision Tree Analysis (DTA) methodology for assessing the cost-effectiveness of the devised strategies.

The Concept of Order of Conflict in Requirements Engineering

Conventional approaches to system design use requirements as boundary conditions against which the design activity occurs. Decisions at a given level of the architecture decomposition can result in the flowing down of conflicting requirements, which are easy to fulfill in isolation but extremely difficult when dealt with simultaneously. Designing against such sets of requirements considerably limits system affordability. Existing research on the evaluation of such conflicts primarily seek to determine the level of conflicts between pairs of requirements. We assert in this paper that these methods are incomplete and using traditional methodologies can result in missing significant conflicts between groups of requirements. We provide a mathematical proof for this assertion and present two case studies that support the mathematical proof. We present the concept of “order of conflict.” The objective of this paper is to prove why pairwise-based conflicting requirements identification and analysis methods based on pairwise comparisons are flawed.

A Categorization Model of Requirements Based on Max-Neef's Model of Human Needs

Requirements categorization is an inherent part of the requirements engineering activity. Conventional approaches use a designer perspective requirements organized according to design needs or attributes, a contractual perspective requirements organized according to procurement or acquisition needs, or a combination of both. Such models present several inconveniences that result in limitation of system affordability: facilitate the generation of overlapping requirements, of design-dependent requirements, and of a mix of requirements applicable to different levels of the architecture decomposition or to different products. The present research proposes a Need-based Categorization NbC model that is system-centric: Requirements are organized around the system. Inspired by Max-Neefs model of human needs, the proposed model supports requirement elicitation by defining only what the system does, how well, where, and what it uses to accomplish it. The model facilitates the identification of constraints that limit the solution tradespace without supporting the satisfaction of new needs, of overlapping requirements, and of requirements that are not applicable to the system. Finally, the proposed model defines requirements in subsets that are associated with value to stakeholders, thus reflecting the actual dependency nature of requirements at a given level of an architecture decomposition, which promotes holistic decisions instead of local optimizations.

Assessing resilience in a regional road-based transportation network

Resilience deals with the response of the system in the face of shock and its ability to continue to provide the expected service delivery levels. In the transportation infrastructure, system shocks due to man-made and natural causes occur frequently and result in substantial economic losses; it is therefore crucial to enhance the resilience of this infrastructure. Improving the resilience of systems creates a need for developing metrics that measure the current resilience of the system and provides a benchmark for evaluating different strategies for improving resilience. In this paper, we propose a framework for assessing the resilience of a regional road network. The methodology introduced in this paper is the Networked Infrastructure Resilience Assessment (NIRA) framework, which allows decision-makers to assess the resilience of networked infrastructures from a multi-metric perspective. The resilience metrics measure the impact of disruptions on the system performance measures. The three identified metrics for road networks are the travel time resilience, environmental resilience and cost resilience. The resilience values are measured by introducing hypothetical disruptions to a network model of a regional transportation network. The NIRA framework is applied to the transportation corridor between Boston and New York City. We also investigate the impact of disruptions on the travellers mode choice.

Using Maslow's hierarchy of needs to define elegance in system architecture☆

Abstract Despite the rising interest in developing elegant systems an integral definition of elegance in system architecture and design is lacking. Current attempts have only been able to describe emergent properties of an elegant design or system. This descriptive approach has resulted in evolving definitions and in an inability to use elegance as criteria to evaluate various design candidates. The present research proposes a need-based definition of elegance that aims at being complete yet adaptable, quantifiable, and that allows comparison between different designs or systems. Using Maslows hierarchy of needs as a paradigm the present research proposes a structural definition that is grounded on the known and unknown needs an elegant system satisfies, rather than on its emergent properties. Specific emergent properties can then be categorized within the structural definition. The benefits of using such type of definition for elegance in system design are two-fold: it ensures completeness because the specific attributes can always be expanded without actually affecting the definition; and it is integral because it provides the necessary flexibility so that designers can tailor the attributes according to their specific environment.

Contextual- and Behavioral-Centric Stakeholder Identification

Proper identification of stakeholders is the first step to bound the system of interest and ultimately to correctly define the problem of concern. Research has traditionally addressed the process of identifying stakeholders using stakeholder-centric methods such as brainstorming (unstructured or with discipline-specific taxonomies). These approaches are grounded on the idea of listing entities that have a relation to the system and then analyze their mutual relationships so that their relative importance with respect to the system can be assessed. Yet, these methods do not provide any mechanism to ensure completeness and thus introduce a high level of uncertainty in the definition of the problem at the beginning of the system life-cycle. The present research proposes instead a contextual- and behavioral-centric approach for stakeholder identification. Using systems thinking the focus is put on understanding all the underlying relationships, be them complex or simple, of the system within its environment and during its existence by comprehensively modeling its socio-technical context and behavior. As a result stakeholders no longer need to be sought, but they comprehensively emerge out of the holistic understanding of the system.