Department: Industrial and Human Factors Engineering ![[clear]](close-x.png "Remove this limiter")
20 matches in the database.
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1.
Crawford, Elizabeth A.
An Evaluation of Discharge Policies at a Generic Acute Care Hospital.
Degree: MS, Industrial and Human Factors Engineering, 2012, Wright State University
► One of the main issues faced within the U.S. healthcare continuum is…
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▼ One of the main issues faced within the U.S. healthcare continuum is ineffective care transition. Ineffective transitions from one area of care to the next can lead to a reduction in quality of care, an increased risk of readmission, and an increase in healthcare costs. According to the National Transitions of Care Coalition (NTOCC), as many as 42% of the hospitals surveyed reported that care transitions during coordinated care delivery do not go as planned. One of the primary reasons for ineffective care transition is poor discharge planning. The purpose of this research is to analyze the effect of various policies for determining the time to discharge a patient on a variety of performance measures at a generic acute care hospital using discrete-event simulation. Three discharge policies are compared: a static policy and two dynamic discharge policies. First, a baseline simulation was created to model the static policy in which a patient is discharged when his/her estimated risk of readmission is acceptable as determined by his/her current health status. To validate the simulation model multiple data sources were utilized, which include the U.S. national statistics on readmission rates and patient pathways, and patient arrival data and bed capacities from an 800+ bed acute care hospital in the U.S. Once the model was validated, we designed and modeled two dynamic discharge policies that account for both the patient's medical condition and the current resource utilization of the emergency department (ED) in determining patient discharges. The performance measures of interest include the following: average time a patient spends waiting and boarding in the ED, the annual hours spent on ambulance diversion, fraction of patients in the ED leaving without treatment, and the total number of readmissions per year. Results showed that the dynamic policies have substantial merit in reducing ED crowding and boarding. The results also suggested a tradeoff between reducing ED measures and the number of 30-day readmissions. The insights from this research could pave path for further research that considers other patient pathways, resource planning and flexibility, and integration with the discharge location decisions.
Advisors/Committee Members: Parikh, Pratik.
Subjects: Engineering; Health Care; Health Care Management; Industrial Engineering
Keywords: Discrete-Event Simulation; Discharge Planning; Readmission
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2.
Fu, Tingting.
Use of Exploratory Data-Mining Techniques to Analyze Associations between Bone-Mineral Density and Relevant Clinical Parameters of Gaucher Disease.
Degree: MS, Industrial and Human Factors Engineering, 2012, Wright State University
► Gaucher disease (GD) is a monogenic disorder with autosomal recessive inheritance, which…
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▼ Gaucher disease (GD) is a monogenic disorder with autosomal recessive inheritance, which results from an acid lysosomal hydrolase, the beta-glucocerebrosidase deficiency. Clinical manifestations of the disease include anemia, thrombocytopenia, hepatosplenomegaly, and skeletal complications. Enzyme replacement therapy (ERT) has been used to treat type 1 GD for more than a decade, and many patients have shown remarkable clinical responses to the treatment, with normalization of blood counts, reduction in liver and spleen size, and improvement in bone symptoms. Many researchers have tried to study the effectiveness of ERT, but previous research has been mainly based on some predetermined hypotheses and traditional analysis methods, which assumed some statistical distributions of the underlying data. In addition, studies have suggested significant individual differences in patients' bone mineral density (BMD) responses to ERT. In this project, we used non-parametric regression tree methods to analyze the BMD data of patients with type 1 GD, in combination with other potentially relevant parameters, including patients' demographics, hematological, visceral, and bone manifestations, to define a parameter subspace that explains the patients' BMD response. Models have been derived for the patient's initial dual-energy X-ray absorptiometry (DXA) Z-score, the rate of change of the patient's DXA Z-scores from his/her first infusion to the current DXA assessment visit, and the rate of change of the patient's DXA Z-scores between two consecutive DXA assessment visits. Modeling results suggest that the patient's initial DXA Z-score is affected by his/her region, treatment with bisphosphonates, gender, and the period between the patient's first infusion and first DXA visit date. The rate of change of the patient's DXA Z-scores from his/her first infusion to the current DXA assessment visit is mostly related to the patient's region, initial DXA Z-score, and ethnicity. In addition, the most predictive covariate of the rate of change of the patient's DXA Z-scores between two consecutive DXA assessment visits is the patient's immediately previous DXA Z-score.
Advisors/Committee Members: Liu, Yan.
Subjects: Engineering
Keywords: Gaucher disease; Enzyme replacement therapy
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3.
Harper, Tiffany Jill.
Implementation of Simulation for Network Service Delivery Point Capacity Analysis.
Degree: MS, Industrial and Human Factors Engineering, 2008, Wright State University
► As businesses consolidate and modernize their operations, the impact on their network…
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▼ As businesses consolidate and modernize their operations, the impact on their network and computing infrastructure is a major consideration. In this thesis, discrete event simulation is used to show how implementation of an Enterprise Resource Planning (ERP) system can impact network performance and ultimately affect end-users. More specifically, the model simulates the flow of data packets across a network, through a Service Delivery Point (SDP), which is comprised of routers, switches, and firewalls that connect a Local Area Network to a Wide Area Network. The model was used to run to determine the affect of more network traffic and additional SDP bandwidth capacity on end-user response time, which is the time for a transaction to be processed and returned to the user. Analysis of model output concluded that a 10%, 20%, and 30% increase in network traffic results in a 98%, 209%, and 352% increase in end-user response time, relative to the current workload. Further experimentation with the model concluded that a 42.5% increase in SDP bandwidth capacity reduced the average response time by 75%. By estimating end-user response time, proper SDP capacity can be planned prior to ERP deployment, to ensure timely completion of end-user transactions that inevitably affects bottom line cost.
Advisors/Committee Members: Ciarallo, Frank.
Subjects: Industrial engineering
Keywords: ERP, simulation
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4.
Hoepf, Michael Raymond.
Domain-specific Core Self-evaluations and Stressors as Predictors of Strains.
Degree: MS, Industrial and Human Factors Engineering, 2010, Wright State University
► The current study examines the use of a frame-of-reference (FOR) in the…
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▼ The current study examines the use of a frame-of-reference (FOR) in the evaluation of core self-evaluations, stressors and strains. The study investigates the prediction that using a FOR that matches predictors and outcomes will result in a stronger relationship between the constructs being measured, specifically CSE, stressors, and strains. In addition, the study examines the extent to which following this procedure will add incremental validity after non-contextualized predictors are controlled. The hypotheses in this study were generally supported, although the hypotheses related to the school domain were not supported as strongly as those related to general and work domain. The author discusses potential implications, limitations and ideas for future research.
Advisors/Committee Members: Bowling, Nathan.
Subjects: Psychology
Keywords: frame-of-reference, stress, strain, core self-evaluations
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5.
Kaliyakuwawala, Kutbi Nuruddin.
Using Two Channel Communication To Study Selective Auditory Attention Using Air And Bone Conducted Interfaces.
Degree: MS, Industrial and Human Factors Engineering, 2009, Wright State University
► The purpose of this study was to evaluate the human capability to…
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▼ The purpose of this study was to evaluate the human capability to use selective auditory attention across the two different hearing pathways, air conduction and bone conduction. Four two channel communication systems were used as a basis for comparison: (1) both channels presented via headphones (left ear and right ear each represent a different channel), (2) two channels presented via loudspeakers placed at 135° and 225°, (3) one channel presented via headphones (both ears) and one channel to bone vibrator (placed at the condoyle), and (4) one channel presented via bone vibrator and one channel via loud speakers (placed at 135° and 225°). The SATASK sentence database was used as auditory stimuli. For the four systems chosen, each channel presented a different sentence, in a different voice, simultaneously. Listeners were assigned a target sentence and asked to record various elements of the SATASK sentence for the target presentation.The results showed that when bone conduction is used as a channel in the communication systems chosen, the speech intelligibility scores were slightly decreased, but the differences were not statistically significant. The only systems where the differences in the scores were significant were the loudspeakers and the system that combined bone conduction and air conduction.
Advisors/Committee Members: Blue, Misty.
Subjects: Armed forces; Biomedical research; Communication; Engineering; Industrial engineering
Keywords: conduction and bone; different; Bone; conduction; vibrator; Auditory; bone vibrator
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6.
Khambhampati, Surya Sudha.
A Tabu Search Heuristic for Multi-Period Clustering to Rationalize Delivery Operations.
Degree: MS, Industrial and Human Factors Engineering, 2008, Wright State University
► Delivery operations use centralized warehouses to serve geographically distributed customers. Resources (e.g.…
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▼ Delivery operations use centralized warehouses to serve geographically distributed customers. Resources (e.g. personnel, trucks, stock, and equipment) are scheduled from the warehouses to distributed locations with the aim of: (a) meeting customer demands and, (b) rationalizing delivery operation costs. My thesis investigates the problem of clustering customers based on their geographical vicinity and their multi-period demands, while optimally scheduling resources. The problem addresses with-and-without capacity constraints of vehicles at the warehouse. This problem is proven to be NP-Hard. Hence, solutions using state-of-the-art exact methods such as branch and bound are not pertinent due to the computation complexity involved. We develop a K-means clustering algorithm for the initial solution and a tabu search heuristic that combines three advanced neighborhood search algorithms: (i) shift move, (ii) shift move with supernodes, and (iii) ejection chain with supernodes, to accelerate convergence.
Advisors/Committee Members: Zhang, Xinhui.
Subjects: Operations research
Keywords: Tabu Search, Clustering
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7.
Kilincli Taskiran, Gamze.
An Improved Genetic Algorithm for Knapsack Problems.
Degree: MS, Industrial and Human Factors Engineering, 2010, Wright State University
► In this study, an improved genetic algorithm (GA) is presented to solve…
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▼ In this study, an improved genetic algorithm (GA) is presented to solve the multidimensional 0-1 knapsack problem (MKP). The MKP is a well-known combinatorial optimization problem and has received wide attention from the operations research community for decades. Although recent advances in computing and optimization technologies have made the solution of small and medium size instances possible, this NP-hard problem, in general, still remains one of the challenging problems yet to be solved.Of the various algorithms developed to solve the MKP, GA seems to be one of the best methods pointed out in the literature. A GA is an iterative search procedure that simulates the evolution process of a population of individuals based on natural selection and genetics. A GA typically starts with a random initial population and uses genetic operators such as crossover and mutation to yield new offspring to replace individuals of current population. GAs, though have been successful in solving MKPs, could be slow in converging to an optimal or near optimal solution. An improved GA is proposed in this study that aims at exploring the use of greedy heuristics and methods to generate multiple diverse solutions to speed GA convergence. Path re-linking (PR), a method to generate new solutions by exploring trajectories that connect high quality solutions, is used to combine elite solutions to further improve the quality of solutions. The combination of uniform crossover and PR allows the integration of randomization and elite solutions analysis to achieve a balance of intensification and diversification to further improve the quality of solutions. Computational studies of benchmark problems suggest that the proposed algorithm was able to quickly achieve good solutions while avoiding being trapped in premature convergence and is on par with some of the state-of-the-art algorithms in the literature. This study demonstrates a systematic method to explore heuristics to generate population generation with diversity, which could significantly influence the convergence of a GA to best solutions. Nevertheless, as our computational results suggest, randomization in crossover is critical for a GA in its overall performance to achieve better quality solutions.
Advisors/Committee Members: Zhang, Xinhui.
Subjects: Engineering; Operations research
Keywords: genetic algorithms; knapsack problem
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8.
Mahadevan, Sriram.
Visualization Methods and User Interface Design Guidelines for Rapid Decision Making in Complex Multi-Task Time-Critical Environments.
Degree: PhD, Industrial and Human Factors Engineering, 2009, Wright State University
► Real-world scenarios are complex dynamic systems that are often overloaded with information.…
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▼ Real-world scenarios are complex dynamic systems that are often overloaded with information. Effective performance of these dynamic systems depends on the objects in such systems and the relationship among them. The control of many of these systems is semi-automated. Human operators constantly monitor and control these systems, assess the situation and often make decisions under time pressure. However, this supervisory control paradigm in a dual-task environment can be a very challenging task. Existing interface design methodologies and techniques have not delved deeply enough into defining information displays for complex, dynamic, time-critical, dual-task environments with capabilities for rapid task change awareness and task resumption while continuously maintaining situation awareness. This research focuses on designing user displays with advanced cueing techniques to support performance in complex dynamic dual-task environments. A primary question addressed in this study is whether visualization methods such as status-at-a-glance displays, interruption recovery tools, and course of action planning tools would assist in maintaining situation awareness, resuming tasks quickly, and effectively perform decision making tasks. The research examines interface design methods to support supervisory awareness in primary and secondary task situations, rapid assimilation when switching to a secondary task, rapid re-assessment upon return to the primary task or secondary task, a course of action solution explorer for successful mission planning/re-planning, and notification systems such as alerts to inform operators about interrupting tasks. This research provides a means to realize an “at-a-glance” decision making environment. The methodology adopted in this research effort used a three-stage process. In stage one, the effect of interruptions on trust and coordination among team members was studied. For stages two and three, the operator tasks and the interface protocols for accomplishing the tasks were designed based on the operator function model. Visual display components were designed to maintain situation awareness, resume the interrupted task scenario quickly, and plan/re-plan course of action for missions and anticipate system status. Multi-modal alert techniques are designed to notify the operator about the interrupting task scenario. The hypotheses related to each stage and the designed components were empirically evaluated using human participants. Results showed that providing an user interface with status-at-a-glance display and interruption recovery tool and other task resumption cues assists the user in maintaining situation awareness and gain change awareness quickly. It was also found that course of action solution exploration tool assists users in quickly designing a feasible course of action and also allows users to re-plan the course of action based on requirements. The use of alerts helps to inform users about a secondary task that would need their attention. A primary contribution from this research is defining a set of user interface design guidelines for use on small screen displays for dual-task supervisory monitoring and control scenarios. Other significant contributions include the design of the status-at-a-glance display, along with the interruption recovery tool, mission planning tool, and the evaluation of alert techniques in such complex, dynamic, time-critical environments.
Advisors/Committee Members: Hill, Raymond.
Subjects: Design; Engineering; Industrial engineering; Information Systems; Systems design
Keywords: Interruptions; dual-task; multi-task; time-critical; supervisory control; rapid decision making; visualization methods; decision support systems; trust; virtual teams
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9.
Mowrey, Corinne H.
An exploratory study of mixed-width aisle layouts for order picking in distribution centers.
Degree: MS, Industrial and Human Factors Engineering, 2011, Wright State University
► Order picking is arguably the most expensive operational activity for a distribution…
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▼ Order picking is arguably the most expensive operational activity for a distribution center (DC), constituting upwards of 50% of total operating costs. Designing an optimum order picking system (OPS) for a DC depends on several system parameters, such as aisle layout, storage system configuration, storage policy, picking method, and picking strategy. From an aisle layout standpoint, traditional DCs utilize either entirely wide or entirely narrow aisles in their picking systems. Wide aisles allow pickers to pass each other, reducing blocking and requiring fewer pickers. However, the space required for wide-aisle systems is high. Narrow aisles utilize less space than wide aisles, but are less efficient because of the high likelihood of congestion experienced by pickers. Space required for the picking area and labor required to perform picking are two significant costs for a DC's OPS. Traditional approaches focus on minimizing either space or minimizing labor rather than integrating the two objectives. We propose a variation to the traditional orthogonal aisle designs where both wide and narrow aisles are mixed within the system, anticipating that the mixed-width aisles may provide a compromise between space and labor. We develop analytical models for space and travel time for systems that employ randomized storage and traversal routing policies. We illustrate the use of these models by developing a cost-based optimization model to determine the optimal aisle configuration for specific OPSs. The objective of this model is to minimize the total system cost which was divided into two components, space and labor. Results indicate that mixed-aisles appear to be optimal for certain OPSs with randomized storage and traversal routing, with the resulting savings in total cost being as high as $48,000 over pure wide aisle systems. Additional benefits may be realized by using mixed-width aisles for other storage policies, such as class-based, and for semi-automated systems, both of which need further research.
Advisors/Committee Members: Parikh, Pratik.
Subjects: Industrial Engineering
Keywords: Industrial Engineering
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10.
Noble, Gregory Daniel.
Application of Modern Principles to Demand Forecasting for Electronics, Domestic Appliances and Accessories.
Degree: MS, Industrial and Human Factors Engineering, 2009, Wright State University
► Royal Philips is a large scale producer of consumer electronics, personal appliances,…
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▼ Royal Philips is a large scale producer of consumer electronics, personal appliances, lighting, and healthcare appliances. Demand data from 12 Business Units (BU) of Royal Philips was examined in the study; four business units from each of three divisions: DAP, PA, and CE. From the data supplied, different forecast techniques were evaluated to determine which procedure produces the highest quality forecasts. Three forecasting techniques were evaluated using the provided data. The three forecasting techniques evaluated are the exponential smoothing forecasting method, the exponential smoothing with a linear trend forecasting method, and the Winters forecasting method. The Visual Basic for Applications (VBA) language was used to implement the functionality of the exponential smoothing, exponential smoothing with linear trend, and the winters forecasting methods forecasting models into Microsoft Excel for this study. Additionally, VBA was used to compute the Mean Absolute Error, which was used to compare each of the models. Overall, the exponential smoothing with a linear trend forecasting method is the best forecasting model for the examined business units. The exponential smoothing with a linear trend model should be used in most cases where the coefficient of variance of the demand data is small. The exponential smoothing model should be used in most cases where the coefficient of variance is of the demand data is large. The Winters method forecasting models had much higher variability in the resulting forecasts of the examined business units. This higher variability may have been due to the complexity in the estimation of the model parameters. Thus, the Winters method, while good in theory, isn’t necessarily the best choice for forecasting in practice with the examined business units and similar products.
Advisors/Committee Members: Ciarallo, Frank.
Subjects: Engineering; Industrial engineering; Operations research
Keywords: Demand Forecasting; Application of Forecasting; Application of Demand Forecasting; Forecasting for Electronics; Forecasting for Domestic Appliances; Forecasting for Accessories; Exponential Smoothing; Exponential Smoothing with a Linear Trend
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11.
Pillala, Lavanya.
Use Of Web-Based Lessons Of Statistical Concepts With Graphics And Animation To Enhance The Effectiveness Of Learning.
Degree: MS, Industrial and Human Factors Engineering, 2010, Wright State University
► Statistics is of critical importance to engineers. However, many engineering students struggle…
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▼ Statistics is of critical importance to engineers. However, many engineering students struggle to grasp the meaning of statistical concepts and the idiosyncrasies of statistical methodologies. Because of this problem, instructors of statistics are constantly searching for better ways to help students understand statistical concepts. The goal of this project is to design and develop web-based lessons that use graphics and animations to enhance the effectiveness of students’ learning of statistical concepts. Lessons of three important statistical concepts have been developed for this thesis - normal distribution, central limit theorem and confidence & tolerance intervals - following well-recognized instructional design development processes and principles. A between-subject experiment was conducted with 20 freshmen engineering students as research participants. The experimental results suggest that compared to the traditional instruction method, the web-based lessons can significantly enhance students’ learning outcomes (by 29.8%) and their satisfaction with the learning process (by 19.2%).
Advisors/Committee Members: Liu, Dr. Yan.
Subjects: Education; Mathematics education; Statistics; Teaching
Keywords: Teaching statistics; Central limit theorem; Normal distribution; Confidence interval; web-based instruction; statistical conepts
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12.
Ponangi, Preethi Vinayak.
Cognitive Cyber Weapon Selection Tool Empirical Evaluation.
Degree: MS, Industrial and Human Factors Engineering, 2011, Wright State University
► Keeping in pace with the latest technological innovations in the cyber world,…
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▼ Keeping in pace with the latest technological innovations in the cyber world, the misuse of this powerful infrastructure has also increased proportionally. Although a lot of recent attacks have been documented in the mainstream media, counter measures for cyber defense mechanism have only received some attention in the recent research literature. Most of the global attacks in the cyber space have proved to be carefully planned premeditated attacks. Considering that most of these attacks are co-coordinated by humans, a new area of psychological weaponry is being investigated by the research community. This study aims to empirically evaluate the effectiveness of the cyber weapon suite of tools to deploy cognitive cyber weapons onto an adversary's computer. The user behavior was assessed based on their performance during the experiment pertaining to each task and measures such as number of repetitions, total time taken to complete each task, total number of emails exchanged by a group and user confidence were considered to evaluate CCWST effectiveness. The results showed that the hypotheses were supported thereby reinforcing the effectiveness of CCWST as a powerful tool to induce cognitive changes in an adversary's thought process.
Advisors/Committee Members: Narayanan, Sundaram.
Subjects: Engineering
Keywords: Cyber warfare, Cognitive weapons, Cognitive Cyber Weapon Selection Tool, Cyber operator, Cognitive weapon selection
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13.
Ponnavolu, Ramya Reddy.
Impact of Culture and Age on the use of Social Networking Websites.
Degree: MS, Industrial and Human Factors Engineering, 2010, Wright State University
► Social networking websites have become very popular amongst people of all ages…
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▼ Social networking websites have become very popular amongst people of all ages in recent times. These websites have brought into existence a new form of data - 'User generated content'. Companies everywhere have begun to identify the potential of these sites and have commenced efforts to take advantage of the profitable opportunities available. In spite of all this, it is reasonable to say that the latent possibilities in social networking sites are yet to be fully explored. This is due to the fact that the technology is still young and research on its potential is still ongoing. The current research is also an effort in this direction. The present study examines the impact of culture and age on the use of social networking websites by analyzing the user generated content on the most popular social networking website in USA - Facebook. Five hypotheses were derived and tested using a two-factorial between-subject quasi experiment. Instead of studying all cultural dimensions, this study focuses on the most studied cultural dimension in the literature - collectivism vs. individualism. Eight groups of American subjects were used to represent the individualistic culture and eight groups of Indian subjects were used to represent the collectivist culture. Two age groups were analyzed in both cultures - young group (25 years and below) and old group (35 years and above). ANOVA of the experiment showed that participants from the American groups displayed a tendency to be unique and hence did not have a significant influencer within the groups, while the participants from the Indian groups chose more to be in harmony together and follow rather than lead thus having a more significant individual leader. Testing age, the results indicated that the younger subjects in both cultures were more active than the older group. In addition, the experiment indicated significant interaction effect between age and culture on the activity levels of the participants. Culture and age were also significant in the participants' preferences of topics of discussions in Facebook.
Advisors/Committee Members: Narayanan, Sundaram.
Subjects: Information Systems
Keywords: Social Networking Websites; age; culture
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14.
PRAJAPATI, MEENAKSHI.
A Stochastic Production Planning Model Under Uncertain Demand.
Degree: MS, Industrial and Human Factors Engineering, 2008, Wright State University
► Production planning plays a vital role in the management of manufacturingfacilities. The…
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▼ Production planning plays a vital role in the management of manufacturingfacilities. The problem is to determine the production loading plan consisting of the quantity of production and the workforce level - to fulfill a future demand. Although the deterministic version of the problem has been widely studied in the literature, the stochastic production planning problem has not. The application of production planning models could be limited if the stochastic nature of the problem, for example, uncertainty in future demand, is not addressed. This study addresses such a stochastic production planning problem under uncertain demand and its application in an enclosure manufacturing facility. The thesis first addresses the forecast of the demand where seasonal fluctuation is present. A decomposition model is utilized in the forecast and compared with other forecasting methods. Although forecast models could be used to improve the accuracy of forecast, error and uncertainty still exists. To deal with this uncertainty, a two stage stochastic scenario based production planning model is developed to minimize the total cost consisting of production cost, labor cost, inventory cost and overtime cost under uncertain demand. The model is solved with data from a local manufacturing facility and the results are compared with various deterministic production models to show the effectiveness of the developed stochastic model. Parametric analysis are performed to derive managerial insights related to issues such as overtime usage and inventory holding cost and the proper selection of scenarios under pessimist, neutral and optimist forecasts. An extension of the stochastic model, i.e., a robust model is also solved in an effort to minimize changes in the solutions under various scenarios. The stochastic production planning model has been implemented in the manufacturing facility, provided guidance for material acquisition and production plans and has dramatically increased the company’s bottom line. As a result, it’s estimated an approximately annual savings of $340,000 in inventory cost can be achieved for the company in the next few years.
Advisors/Committee Members: Zhang, Xinhui.
Subjects: Industrial engineering
Keywords: optimization; production planning; stochastic programming; uncertain demand
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15.
Reis, George Angelo.
The Effects of Depth and Eccentricity on Visual Search in a Depth Display.
Degree: MS, Industrial and Human Factors Engineering, 2009, Wright State University
► The attribute of depth has been shown to provide saliency or conspicuity…
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▼ The attribute of depth has been shown to provide saliency or conspicuity for items in a visual search task. Novel displays that present information in real physical depth offer potential benefits. Previous research has studied depth in visual search but depth was mostly realized without real physical separation of display elements. This study aimed to better understand the effects of real physical depth and eccentricity on visual search in a depth display. Through this understanding, we can appropriately utilize this new technology. An experiment was conducted to test four hypotheses regarding how depth, eccentricity, target feature, and screen location would affect target acquisition speed. An ANOVA of the experiment's data suggests that physical depth can enhance the target search speed, especially when combined with other attributes for guiding attention. Visual search performance can be hampered when eccentricity increases for the target item. In addition, there seem to be interactions between target attributes and eccentricity.
Advisors/Committee Members: Liu, Yan.
Subjects: Engineering; Experiments; Industrial engineering; Information Systems; Psychology
Keywords: depth, visual search, multi-layered display, eccentricity
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16.
Soni, Jasminkumar B.
Determining The Effect Of Speaker's Gender And Speech Synthesis On Callsign Acquisition Test (CAT) Results.
Degree: MS, Industrial and Human Factors Engineering, 2009, Wright State University
► Effective and efficient speech communication is one of the leading factors for…
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▼ Effective and efficient speech communication is one of the leading factors for success of battlefield operation. With the increases in the levels of gender diversity in military services, it is important to assess the effectiveness of voice for both genders in communication systems. The purpose of this research study was to determine the effect of the speaker's voice (male and female) on the speech intelligibility (SI) performance of the Callsign Acquisition Test (CAT). In addition, the effects of synthesized speech were evaluated. The CAT test is a new SI test that has been developed for military use. A group of 21 listeners with normal hearing participated in the study. Each participant listened to four different lists of CAT (male and female natural recorded speech, and male and female synthetic speech) at two signal-to-noise ratios. White noise was used as a masking noise and various speech files were mixed at signal-to-noise ratios -12 dB and -15 dB. Each wordlist was played at 50dB and 53dB mixed with white noise at 65dB. Each listener participated in a total of 8 tests presented in a random fashion. Testing was performed in a sound treated booth with loud speakers. Test results demonstrated that male speech and natural voice have higher SI results than female speech and synthetic voice respectively. Also statistical analysis concluded that female speech, -15 dB SNR, synthetic voice, and combination effect of female speech and synthetic voice all have significant effect on CAT test results in the presence of white noise. All tests used significance levels alpha = 0.5.
Advisors/Committee Members: Blue, Misty.
Subjects: Acoustics; Biomedical research; Education; Engineering; Industrial engineering
Keywords: Callsign Acquisition Test, Speech Intelligibility
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17.
Veeraragavan, Ramanan.
DROP-SHIPPING AT A PROMOTIONAL PRODUCTS DISTRIBUTOR.
Degree: MS, Industrial and Human Factors Engineering, 2011, Wright State University
► During the current economic times, companies are trying to reduce costs by…
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▼ During the current economic times, companies are trying to reduce costs by incorporating new strategies into their business plan. Supply chain, in particular the distribution network is one area where an improvement can bring in a healthy return on investment to a company. Drop-shipping is a distribution strategy whereby customer orders are fulfilled by directly delivering products from manufacturer's facility, instead of storing these products at the warehouse. Drop-shipping helps in reducing inventory and material handling costs at the warehouse, but may increase transportation costs due to frequent shipments. This research was motivated by the current operations at a promotional products distributor in the Midwest US. This distributor wanted to decide which products to drop-ship versus stock in the warehouse. We develop a mixed integer programming (MIP) model to categorize the products as ‘to be drop-shipped' or ‘kept in warehouse' with the objective of minimizing the total distribution cost. This single-period MIP model assumes deterministic demand, all-unit transportation LTL and parcel rates, and warehouse space. To solve larger problem instances, a Ruin and Recreate (RR) based heuristic is proposed. Numerical results indicate that a savings in warehouse space ranging between 28-53% and an additional cost savings of up to 5.2%. A case study involving realistic data obtained from the distributor is presented and avenues for future research in this area are discussed.
Advisors/Committee Members: Parikh, Pratik.
Subjects: Operations Research
Keywords: Drop-shipping; deterministic; mathematical model; heuristic
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18.
Vijayakumar, Bharathwaj.
SCHEDULING SURGICAL CASES IN A CONSTRAINED ENVIRONMENT.
Degree: MS, Industrial and Human Factors Engineering, 2011, Wright State University
► This research examines a complex surgical case scheduling problem for a publicly-funded…
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▼ This research examines a complex surgical case scheduling problem for a publicly-funded hospital in the Midwest United States. Publicly-funded hospitals are typically under tight budget constraints and these hospitals strive to maximize the utilization of their resources such as beds, staff, equipment, operating rooms, etc. These resources are relatively fixed for a publically funded hospital. A manual scheduling approach followed by this hospital does not guarantee optimal solutions and consequently has led to large variation in the utilization of resources. This real-world problem is described in this research as a multi-day, multi-resource, and patient-priority-based surgical case scheduling problem with the objective of maximizing the weighted sum of surgical case priorities. The surgical case scheduling problem herein is conceptualized as an unequal-sized multi-dimensional multi-bin dual bin-packing problem. A mixed integer programming model is proposed to generate implementable schedules. For each surgical case, the solution obtained will provide detail information about the start time and day of the surgery, the operating room to perform the surgery, and the surgeon's name. Resource availability, patient priorities, and surgical time of the surgeons are key features included in the model. However, the combinatorial nature of this problem limited the MIP model to solving only small problem instances. Consequently, an efficient First Fit Decreasing based heuristic is proposed and its performance is benchmarked against the MIP model. The benefit of pooling surgical cases over the commonly used First Come First Serve scheduling policy is also demonstrated. Results quantify the extent to which pooling can increase the number of high priority surgeries performed.
Advisors/Committee Members: Parikh, Pratik.
Subjects: Industrial Engineering; Mathematics; Operations Research; Surgery
Keywords: surgical case scheduling, operations research, heuristics, mathematical model, mixed integer programming, first fit decrease
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19.
Wallace-Finney, Sheena R.
Determining the Optimal Aisle-Width for Order Picking in Distribution Centers.
Degree: MS, Industrial and Human Factors Engineering, 2011, Wright State University
► Many companies use distribution centers (DC) as hubs for storing and distributing…
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▼ Many companies use distribution centers (DC) as hubs for storing and distributing products to customers (e.g., wholesalers, retailers, or consumers). Order picking, a critical activity in every DC, refers to retrieving products from the storage locations to fulfill customer orders. It accounts for over 50% of the DC operating cost. Order picking system design involves several decisions, such as layout of the picking area, storage policy, picking method, material handling equipment, and information technology, to name a few. Aisle configuration (number, length, width, and orientation) is a critical layout decision as it directly affects picker productivity and required space. Previous research in picking system layout optimization has focused on number and orientation of picking aisles, but not on the selection of an appropriate aisle-width (wide or narrow). Wide aisles require more space, but experience less congestion; in contrast, narrow aisles require less space, but may induce congestion among pickers. Congestion leads to a reduction in picker productivity, thus increasing labor cost to satisfy required system throughput. Our focus in this research is in determining the optimal aisle-width by evaluating the cost (labor and space) tradeoffs between wide-aisle and narrow-aisle system configurations for both manual and semi-automated systems. We propose a cost-based optimization model and use previously developed travel-time and picker-blocking models in solving the optimization model. We account for several system parameters, such as space and labor costs, throughput, system size, number of aisles, storage levels, and items picked in a tour in our experimentation. Our results indicate a preference for wide-aisle systems when cost of labor and required throughput are high, while they indicate a preference for narrow-aisle systems when cost of space and number of storage locations are high.
Advisors/Committee Members: Parikh, Pratik.
Subjects: Operations Research
Keywords: Warehouse, Distribution Center, Aisle width, layout, aisle configuration
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20.
Yeh, Shea-Tinn.
Integrated Faceted Browser and Direct Search to Enhance Information Retrieval in Text-Based Digital Libraries.
Degree: MS, Industrial and Human Factors Engineering, 2009, Wright State University
► Browsing and searching are two prominent paradigms in information retrieval. In current…
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▼ Browsing and searching are two prominent paradigms in information retrieval. In current digital library implementations, exploratory browsing is sometimes not available as an option. When offered, it is commonly presented as an alphabetical listing of chosen categories depending on the scope of the digital collections. In addition, users have to switch between different information spaces for browsing and searching. This research proposes an information retrieval paradigm of integrated faceted browser and direct search interfaces for text-based digital libraries. Experimental results show that compared to a conventional alphabetical browser, the faceted browser can significantly improve the effectiveness (by 30.8%, p = 0.015) and efficiency (by 11.3%, p = 0.001) of information retrieval. Also, compared to un-integrated alphabetical browser with direct search interfaces, the integrated faceted browser with direct search interfaces can significantly improve the effectiveness of information retrieval (by 35.7%, p = 0.03) and bring users greater satisfaction (by 34.8%, p < 0.03) with the process.
Advisors/Committee Members: Liu, Yan.
Subjects: Information Systems
Keywords: digital library; faceted browsing; electronic information resource searching; information retrieval
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