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Full-Text Articles in Operations Research, Systems Engineering and Industrial Engineering

Modelling Vessel Traffic Service To Understand Resilience In Everyday Operations, Gesa Praetorius, Erik Hollnagel, Joakim Dahlman Aug 2015

Modelling Vessel Traffic Service To Understand Resilience In Everyday Operations, Gesa Praetorius, Erik Hollnagel, Joakim Dahlman

Gesa Praetorius

Vessel Traffic Service (VTS) is a service to promote traffic fluency and safety in the entrance to ports. This article׳s purpose has been to explore everyday operations of the VTS system to gain insights in how it contributes to safe and efficient traffic movements. Interviews, focus groups and an observation have been conducted to collect data about everyday operations, as well as to grasp how the VTS system adapts to changing operational conditions. The results show that work within the VTS domain is highly complex and that the two systems modelled realise their services vastly differently, which in turn ...


The Viking Biological Investigation: Preliminary Results, Harold Klein, Norman Horowitz, Gilbert Levin, Vance Oyama, Joshua Lederberg, Alexander Rich, Jerry Hubbard, George Lobby, Patricia Straat, Bonnie Berdahl, Glenn Carle, Frederick Brown, Richard Johnson Jun 2014

The Viking Biological Investigation: Preliminary Results, Harold Klein, Norman Horowitz, Gilbert Levin, Vance Oyama, Joshua Lederberg, Alexander Rich, Jerry Hubbard, George Lobby, Patricia Straat, Bonnie Berdahl, Glenn Carle, Frederick Brown, Richard Johnson

Frederick S. Brown

Three different types of biological experiments on samples of martian surface material ("soil") were conducted inside the Viking lander. In the carbon assimilation or pyrolytic release experiment, $^{14}$CO$_{2}$ and $^{14}$CO were exposed to soil in the presence of light. A small amount of gas was found to be converted into organic material. Heat treatment of a duplicate sample prevented such conversion. In the gas exchange experiment, soil was first humidified (exposed to water vapor) for 6 sols and then wet with a complex aqueous solution of metabolites. The gas above the soil was monitored by gas ...


Chloroperoxidase: Ii. Utilization Of Halogen Anions, Lowell Hagar, David Morris, Frederick Brown, Horst Eberwein Jun 2014

Chloroperoxidase: Ii. Utilization Of Halogen Anions, Lowell Hagar, David Morris, Frederick Brown, Horst Eberwein

Frederick S. Brown

Chloroperoxidase can utilize chloride, bromide, and iodide ions and catalyze the formation of a carbon-halogen bond in the presence of suitable acceptor molecules. Suitable halogen acceptor molecules are β-keto acids, cyclic β-diketones, and substituted phenols.

An optical assay has been developed to measure the halogenating activity of chloroperoxidase. The assay is based on the conversion of monochlorodimedon to the corresponding gem-dihalo derivative. The optical assay is based on the loss of absorbance at 278 mµ associated with the formation of the dihalo derivative from the monohalo compound.

In the optical assay, crystalline chloroperoxidase preparations catalyze the formation of the ...


Seed Meal Constituents, Oxazolidinethiones And Volatile Isothiocyanates In Enzyme-Treated Seed Meals From 65 Species Of Cruciferae, Frederick Brown, M. E Daxenbichler, C. H Vanetten, Q. Jones Jun 2014

Seed Meal Constituents, Oxazolidinethiones And Volatile Isothiocyanates In Enzyme-Treated Seed Meals From 65 Species Of Cruciferae, Frederick Brown, M. E Daxenbichler, C. H Vanetten, Q. Jones

Frederick S. Brown

Information is unavailable concerning the amounts and types of isothiocyanate-yielding glucosides in many species of Cruciferae seeds. Because such compounds have nutritional significance, a number of unreported species were investigated. Information about the parent thioglucosides was obtained by estimation of the oxazolidinethione and steam-volatile isothiocyanate contents of enzymatic hydrolyzates of the seed meals. Significant amounts of oxazolidinethione were found in hydrolyzates from 11 species not previously known to contain such glucosidic precursors. Oxazolidinethione (calculated as vinyl oxazolidinethione) measurements ranged from 0 to 19.3 mg. per gram of pentane- hexane-extracted meal. Total volatile isothiocyanate measurements (calculated as butenyl isothiocyanate) ranged ...


Racemization Of Amino Acids In Sediments From Saanich Inlet, British Columbia, Keith Kvenvolden, Etta Peterson, Frederick Brown Jun 2014

Racemization Of Amino Acids In Sediments From Saanich Inlet, British Columbia, Keith Kvenvolden, Etta Peterson, Frederick Brown

Frederick S. Brown

In sediments spanning the last 9000 years from Saanich Inlet L enantiomers of amino acids are most abundant, but the percentages of D enantiomers increase with age, apparently because of partial racemization. Of the amino acids measured, glutamic acid and alanine show the greatest degree of racemization; leucine, isoleucine, and valine show the least.


Maritime Traffic Management: A Need For Central Coordination?, Fulko Van Westrenen, Gesa Praetorius Jan 2014

Maritime Traffic Management: A Need For Central Coordination?, Fulko Van Westrenen, Gesa Praetorius

Gesa Praetorius

Traffic management is not formally organised in the maritime domain. Ships are autonomous and find their own way. Traffic is organised through rules, regulations, and “good seamanship”; it is a distributed system. In areas of high traffic-density support is proved by vessel traffic service (VTS) to promote traffic safety and fluency. VTS does not take control. This organisational structure has proven itself in situations with sufficient resources. When resources become insufficient (e.g. not enough sailing space), the traffic needs an organising mechanism. In this article, the authors argue that the most promising way to do this is by organising ...


Mle+: A Tool For Integrated Design And Deployment Of Energy Efficient Building Controls, Willy Bernal, Madhur Behl, Truong Nghiem, Rahul Mangharam Jan 2013

Mle+: A Tool For Integrated Design And Deployment Of Energy Efficient Building Controls, Willy Bernal, Madhur Behl, Truong Nghiem, Rahul Mangharam

Truong X Nghiem

We present MLE+, a tool for energy-efficient building automation design, co-simulation and analysis. The tool leverages the high-fidelity building simulation capabilities of EnergyPlus and the scientific computation and design capabilities of Matlab for controller design. MLE+ facilitates integrated building simulation and controller formulation with integrated support for system identification, control design, optimization, simulation analysis and communication between software applications and building equipment. It provides streamlined workflows, a graphical front-end, and debugging support to help control engineers eliminate design and programming errors and take informed decisions early in the design stage, leading to fewer iterations in the building automation development cycle ...


A Decision Support Model For The Location Of Hand Sanitizer Dispensers In Hospitals, Laila Cure Dec 2012

A Decision Support Model For The Location Of Hand Sanitizer Dispensers In Hospitals, Laila Cure

Laila Cure

Compliance with hand hygiene practices is directly affected by the accessibility and availability of cleaning agents. Nevertheless, the decision of where to locate these dispensers is often not explicitly or fully addressed in the literature. In this paper, we study the problem of selecting the locations to install alcohol-based hand sanitizer dispensers throughout a hospital unit. We investigate the relevant criteria in selecting dispenser locations that promote compliance with hand hygiene practices, propose metrics for the evaluation of various location configurations, and formulate a dispenser location optimization model that incorporates such criteria. A complete methodology to collect data and obtain ...


Designing Intelligent Agents To Support Long-Term Partnership In Two Echelon E-Supply Networks, Shima Mohebbi, Xueping Li Dec 2012

Designing Intelligent Agents To Support Long-Term Partnership In Two Echelon E-Supply Networks, Shima Mohebbi, Xueping Li

Xueping Li

No abstract provided.


Conversations Around Design Sketches: Use Of Communication Channels For Sharing Mental Models During Concept Generation, Nik Shahman Nik Ahmad Ariff, Petra Badke-Schaub, Ozgur Eris Oct 2012

Conversations Around Design Sketches: Use Of Communication Channels For Sharing Mental Models During Concept Generation, Nik Shahman Nik Ahmad Ariff, Petra Badke-Schaub, Ozgur Eris

Ozgur Eris

In this paper, we present an exploratory protocol study on the use of different communication channels during design sketching. We focus on how individual designers share their mental models with other designers in a group, and analyse their use of graphical, textual, and verbal communications during concept generation.

Our findings suggest that verbal communication plays a role in the sharing of individual mental models during sketching, and complements graphical and textual communication channels. However, design teams can still function without verbal communication in that respect, and address design problems. They seem to compensate for the absence of the verbal communication ...


An Alternative Characterization Of Robust Stability And Stability Radius For Linear Time Delay Systems, Bahram Shafai, Hanai Sadaka, Rifat Sipahi, Jie Chen Apr 2012

An Alternative Characterization Of Robust Stability And Stability Radius For Linear Time Delay Systems, Bahram Shafai, Hanai Sadaka, Rifat Sipahi, Jie Chen

Hanai Sadaka

No abstract provided.


Reinforcement Learning For Joint Pricing, Lead-Time And Scheduling Decisions In Make-To-Order Systems, Xueping Li, Jiao Wang, Rapinder Sawhney Dec 2011

Reinforcement Learning For Joint Pricing, Lead-Time And Scheduling Decisions In Make-To-Order Systems, Xueping Li, Jiao Wang, Rapinder Sawhney

Xueping Li

No abstract provided.


Covering Models And Optimization Techniques For Emergency Response Facility Location And Planning: A Review, Xueping Li, Zhaoxia Zhao, Xiaoyan Zhu, Tami Wyatt Dec 2010

Covering Models And Optimization Techniques For Emergency Response Facility Location And Planning: A Review, Xueping Li, Zhaoxia Zhao, Xiaoyan Zhu, Tami Wyatt

Tami H Wyatt

No abstract provided.


Evaluating The Impact Of Patient Arrival Patterns In The Performance Of Appointment Scheduling Rules, Alcides Santander-Mercado, Jose Zayas-Castro, Laila Cure, Ali Yalcin Dec 2010

Evaluating The Impact Of Patient Arrival Patterns In The Performance Of Appointment Scheduling Rules, Alcides Santander-Mercado, Jose Zayas-Castro, Laila Cure, Ali Yalcin

Laila Cure

This paper evaluates the ability of commonly used Appointment Scheduling Rules (ASRs) in smoothing the effect of environmental factors in the performance of an outpatient scheduling system. ASRs have been widely implemented in outpatient clinics to improve performance measures such as staff idle time, patient waiting time, and facility congestion. However, the successful implementation of an ASR depends on its ability in dealing with the environmental factors affecting the system. Factors such as no-shows, variability of consultation times, patient unpunctuality, walk-in patient arrivals and the number of admitted patients per session affect the performance of the clinics in terms of ...


Challenges And Models In Supporting Logistics System Design For Biomass-To-Bioenergy Industry, Xiaoyan Zhu, Xueping Li, Qingzhu Yang, Yuerong Chen Dec 2010

Challenges And Models In Supporting Logistics System Design For Biomass-To-Bioenergy Industry, Xiaoyan Zhu, Xueping Li, Qingzhu Yang, Yuerong Chen

Xueping Li

No abstract provided.


Intelligent Dynamic Control Of Stochastic Economic Lot Scheduling By Agent-Based Reinforcement Learning, Jiao Wang, Xueping Li, Xiaoyan Zhu Dec 2010

Intelligent Dynamic Control Of Stochastic Economic Lot Scheduling By Agent-Based Reinforcement Learning, Jiao Wang, Xueping Li, Xiaoyan Zhu

Xueping Li

No abstract provided.


Transportation Delays In Supply Networks: Stability Analysis & System Design, Rifat Sipahi, Stefan Lanmer, Silvia-Julian Niculescu, Dirk Helbing Sep 2010

Transportation Delays In Supply Networks: Stability Analysis & System Design, Rifat Sipahi, Stefan Lanmer, Silvia-Julian Niculescu, Dirk Helbing

Rifat Sipahi

No abstract provided.


Key Establishment For Layered Group-Based Wireless Sensor Networks, Xueping Li, Dengfeng Yang, Rapinder Sawhney Dec 2009

Key Establishment For Layered Group-Based Wireless Sensor Networks, Xueping Li, Dengfeng Yang, Rapinder Sawhney

Xueping Li

Establishing pairwise keys for sensors is crucial to secure communications in Wireless Sensor Networks (WSNs). Several key pre-distribution schemes have been proposed to establish pairwise keys, but they are not scalable and suffer from a dramatic degradation of security when the number of compromised sensor exceeds a threshold. In this paper, we propose a Layered Group-based Key Establishment (LGKE) scheme, in which a logic top layer ensures the scalability through an Exclusion Basic System (EBS) technique while a logic low layer adopts a group-based key preload scheme to ensure the security. The security analysis and quantitative evaluation show the superiority ...


Impacts Of Supply Disruptions And Customer Differentiation In A Partial-Backordering Inventory System, Xueping Li, Yuerong Chen Dec 2009

Impacts Of Supply Disruptions And Customer Differentiation In A Partial-Backordering Inventory System, Xueping Li, Yuerong Chen

Xueping Li

In this paper, we study a single-product inventory system which involves a supplier, a retailer, and differentiated customers. The supplier provides products to the retailer which in turn sells products to its customers. The supplier is unreliable and is subject to random disruptions. The retailer adopts a periodic-review inventory policy, under which the retailer reviews its inventory position every a fixed period of time and decides whether a replenishment is needed or not. Partial backordering is applied when a stockout occurs. That is, under the situations of stockouts, customers can choose either to backorder products or to abandon the purchase ...


Mac Pgp Encryption, Elizabeth Scheyder Dec 2008

Mac Pgp Encryption, Elizabeth Scheyder

Elizabeth C Scheyder

No abstract provided.


Effective Precedence Constrained Scheduling In A Make-To-Order Environment, Xueping Li, Jiao Wang, Rapinder Sawhney Dec 2008

Effective Precedence Constrained Scheduling In A Make-To-Order Environment, Xueping Li, Jiao Wang, Rapinder Sawhney

Xueping Li

The make-to-order assembly lines have gradually replaced the traditional mass production assembly lines. These assembly lines follow a 'make-to-order' production policy, which are featured with a short production lead time, small number of working stations and highly skilled workers. In order to maximise the throughput under the resource (machine, labour and time) constraints, the problem of minimising makespan with general precedence constraints is addressed in this paper. A mathematical model of the problem is presented and a new heuristic, genetic job-oriented list scheduling (GJLS) is developed. Computational experiments indicate that the proposed algorithm outperforms the existing Graham's list scheduling ...


A Comparative Analysis Of Predictive Data-Mining Techniques, Xueping Li Dec 2008

A Comparative Analysis Of Predictive Data-Mining Techniques, Xueping Li

Xueping Li

It is non-trivial to select the appropriate prediction technique from a variety of existing techniques for a datasets, since the competitive evaluation of techniques (bagging, boosting, stacking and meta-learning) can be time consuming. This paper compares five predictive data mining techniques on four unique datasets that have a combination of the following characteristics: few predictor variables, many predictor variables, highly collinear variables, very redundant variables and the presence of outliers. Different data mining techniques, including multiple linear regression (MLR), principal component regression (PCR), ridge regression, partial least squares (PLS) and non-linear partial least squares (NLPLS), are applied to each of ...


Enhancing Design Learning Using Groupware, Andrew Wodehouse, Ozgur Eris, Hillary Grierson, Ade Mabogunje Dec 2006

Enhancing Design Learning Using Groupware, Andrew Wodehouse, Ozgur Eris, Hillary Grierson, Ade Mabogunje

Ozgur Eris

Project work is increasingly used to help engineering students integrate, apply and expand on knowledge gained from theoretical classes in their curriculum and expose students to `real world' tasks. To help facilitate this process, the department of Design, Manufacture and Engineering Management at the University of Strathclyde has developed a web-based groupware product called LauLima to help students store, share, structure and apply information when they are working in design teams. This paper describes a distributed design project class in which LauLima has been deployed in accordance with a Design Knowledge Framework that describes how design knowledge is generated and ...


Insisting On Truth At The Expense Of Conceptualization: Can Engineering Portfolios Help?, Ozgur Eris Dec 2005

Insisting On Truth At The Expense Of Conceptualization: Can Engineering Portfolios Help?, Ozgur Eris

Ozgur Eris

Teaching and promoting conceptual thinking in engineering education is challenging. Two recently introduced design thinking models are compared in order to explore the reasons behind this challenge. The comparison results in key distinctions between divergent and convergent thinking, and between concept and knowledge domains. The differentiating principle is shown to be a common principle of the two models, truth-value, or logical status, of the propositions that engineers make. Building on this insight, divergent thinking by inquiry is identified as a mechanism for promoting conceptual thinking, and a specific implementation of engineering portfolios is proposed as a pedagogical tool.