Simulated Annealing and Threshold Accepting are two stochastic search algorithms that have been successfully used on a variety of complex and difficult problem sets. Due to their stochastic nature they are not guaranteed to produce the same result for each run. This means that these techniques actually produce a distribution...
The performance of transit networks must be measured on a regular basis to understand how well these complex systems fulfill their intended purpose and to identify potential opportunities for improvement. Measuring transit network performance is only achievable by defining a specific set of transit network performance indicators (TNPIs). Different schemes...
Qualitative data analysis (QDA) is a time consuming and, potentially unreliable research activity. In qualitative research, a number of tasks must be repeated for every new research case, even if each case is closely related or is in the same area of study.
Existing QDA applications provide users with a...
Since the introduction of lean manufacturing by Toyota and publication by Womack and Jones, organizations have realized sizeable gains through lean process improvement. The spread of lean practices across organizations and industries – from manufacturing to healthcare and construction – requires adjustments of the lean process and, in the case...
Since the Industrial Revolution, automated systems have increasingly become a part of everyday life. Automated systems range in scale and scope from simple assists to complete robotic replacements. Inexpensive integrated circuits, sensors and microprocessors have allowed automated systems to become smaller, cheaper and more prevalent. Identifying appropriate opportunities for automation,...
As modern systems continue to increase in size and complexity, they pose significant safety and risk management challenges. System engineers and much of the government research efforts are focused on understanding the attributes and characteristics that emerge from the interactions of components and subsystems. As a result, the objective of...
Improving the understanding the relations of sustainability behaviors in manufacturing systems and actively engaging with manufacturers (especially SMEs) in sustainability efforts is key to the long-term success of U.S. industry and the natural environment. This study addresses this urgent need by establishing a systemic approach for the design of costing...
An open area of research in complex systems is to move reliability and failure assessments earlier in the engineering design process. When compared to later design, early decisions are cost effective and have a large impact on the system. Standard methods are limited by the availability of data and often...
Chain saws are a common tool used by large logging corporations and family homesteads to manage forests, limb trees and buck lumber. A significant cost of operation is the continuous required supply of bar and chain oil. Consumers and logging corporations desire a lubricant with a high performance to cost...
Both researchers and practitioners in fields related to emergency management (EM) use a variety of frameworks for different purposes including analysis, learning, and operations. Despite existing approaches in EM, such as comprehensive emergency management (CEM), the research community has been urged to construct a general normative theory for emergency management...
Heating, ventilation, and air conditioning systems represent nearly half of building energy usage in the United States. Recent building regulations requiring increased air turnover within buildings will result in even greater air conditioning usage. To alleviate these concerns, membrane-based heat-and-moisture exchangers known as energy recovery ventilators have been developed to...
Organizations are constantly looking for innovative strategies to face more stringent competitive environments and the ever increasing market globalization. An alternative these organizations can pursue to respond to these challenges is to optimize their supply chain network (SCN). Important considerations when optimizing a SCN involve determining locations for plants and...
The myriad of problems facing the world today are increasingly complex, dynamic, and transcend multiple domains necessitating the need for an equally complex and trans-disciplinary approach to solve these problems. Systems thinking promises to provide the skills necessary for all citizens of the world, not just the experts, to handle...
A flexible flowshop, comprised of one or more stages having unrelated parallel machines, is investigated in this research. Unrelated parallel machines can perform the same function but have different capacity or capability. Since this problem is motivated by industry research, dynamic job release times and dynamic machine availability times have...
Hydrogen has been shown to be a promising replacement for fossil fuels for use in light duty vehicles because it is a clean, renewable and plentiful resource with a high gravimetric energy density. However, in order to obtain an acceptable volumetric energy density, densification of the hydrogen is required. Adsorptive...
Given the current abundant supply and cheap price of natural gas (NG) in the United States, there is a significant opportunity to use this fuel for transportation. However, there are few fueling stations for consumers. To address this need, a dual-mode engine has been developed where in one mode all...
The competitiveness level of Formula Student is consistently increasing. Teams must allocate resources to develop new innovative designs to gain a competitive edge. Managing team resources effectively is critical to a team’s success. Reducing the resources required to manufacture specific components can be used to allocate resources to other beneficial...
Innovation is a key element for a product to achieve market success, but identifying it within product or even defining the term is a difficult task. Identifying innovation has been approached in many different ways. Experts in design engineering may identify innovative designs based on an analysis of a product's...
Recent work has shown humanoid robots with spinal columns, instead of rigid torsos, benefit from both better balance and an increased ability to absorb external impact. Similarly, snake robots have shown promise as a viable option for exploration in confined spaces with limited human access, such as during power plant...
In this work, flow through synthetic arrangements of contacting spheres is studied
as a model problem for porous media and packed bed type flows. Direct numerical
simulations are performed for moderate pore Reynolds numbers in the range,
10 ≤ Re ≤ 600, where non-linear porescale flow features are known to...