Industrial & Manufacturing Engineering Masters Theses

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Adaptive Production Planning and Scheduling for the Make-to-order DNA Manufacturing System
(North Dakota State University, 2010) Song, Dan
This thesis develops an adaptive production planning and scheduling system for the make-to-order plasmid (DNA) manufacturing system. The system, which has stochastic nature and random demand, was represented by a mathematical programming model first. Then in order to solve it, discrete-event simulation models were developed to generate a feasible schedule that maximizes the production throughput in the planning horizon in a mix-product type environment. A special heuristic order selecting and splitting procedure was designed to aid the production planning and scheduling process. Experiments were conducted to evaluate the algorithm and results are compared with those obtained by using four classic dispatching rules, such as first come first served (FCFS) and shortest processing time (SPT). To take advantage of simulation results, a rule-based expert system was created with pre-defined scheduling rules. Rules regarding production planning and scheduling can be used by human schedulers easily and the system is very flexible in further extension.
CFD Heat Transfer Simulation of the Human Upper Respiratory Tract for Oronasal Breathing Condition
(North Dakota State University, 2011) Srinivasan, Raghavan
In this thesis. a three dimensional heat transfer model of heated airflow through the upper human respiratory tract consisting of nasal, oral, trachea, and the first two generations of bronchi is developed using computational fluid dynamics simulation software. Various studies have been carried out in the literature investigating the heat and mass transfer characteristics in the upper human respiratory tract, and the study focuses on assessing the injury taking place in the upper human respiratory tract and identifying acute tissue damage based on level of exposure. The model considered is for the simultaneous oronasal breathing during the inspiration phase with high volumetric flow rate of 90/liters minute and a surrounding air temperature of 100 degrees centigrade. The study of the heat and mass transfer, aerosol deposition and flow characteristics in the upper human respiratory tract using computational fluid mechanics simulation requires access to a two dimensional or three dimensional model for the human respiratory tract. Depicting an exact model is a complex task since it involves the prolonged use of imaging devices on the human body. Hence a three dimensional geometric representation of the human upper respiratory tract is developed consisting of nasal cavity, oral cavity, nasopharynx, pharynx, oropharynx, trachea and first two generations of the bronchi. The respiratory tract is modeled circular in cross-section and varying diameter for various portions as identified in this study. The dimensions are referenced from the literature herein. Based on the dimensions, a simplified model representing the human upper respiratory tract is generated.This model will be useful in studying the flow characteristics and could assist in treatment of injuries to the human respiratory tract as well as help optimize drug delivery mechanism and dosages. Also a methodology is proposed to measure the characteristic dimension of the human nasal and oral cavity at the inlet/outlet points which are classified as internal measurements.
A Domain-Knowledge Modeling of Hospital-Acquired Infection Risk in Healthcare Personnel From Retrospective Observational Data: A Case Study for Covid-19
(North Dakota State University, 2022) Huynh, Phat
Healthcare personnel (HCP) is facing a consistent risk of viral infections. We proposed a domain-knowledge-driven infection risk model to quantify the individual HCP and the population-level risks. For individual-level risk estimation, a time-variant model was proposed to capture the disease transmission dynamics. At the population-level, the infection risk was estimated using a Bayesian network model constructed from three feature sets. For model validation, we investigated the case study of the Coronavirus disease. The variance-based sensitivity analysis indicated that the uncertainty in the estimated risk was attributed to two variables: the number of close contacts and the viral transmission probability. We further validated the individual risk model by considering six occupations in the U.S. O*Net database. For the population-level risk model validation, the infection risk in Texas and California was estimated. The accurate estimation of infection risk will significantly enhance the PPE allocation, safety plans for HCP, and hospital staffing strategies.
Dynamic Pricing in Supply Chains Bringing the Perishable Approach to Dynamic Car Market
(North Dakota State University, 2014) Tripathi, Prateek
In a business environment, using dynamic pricing is a standard practice, especially in the management of revenue. Given the availability of online information concerning inventory and pricing, customers are in a position to understand pricing strategies that sellers employ, and at the same time to be able to develop a possible response strategy. In this thesis, Dynamic Pricing in the Supply Chain: Bringing the Perishable Approach to Dynamic Car Market is investigated and evaluated. This study incorporates strategic consumer response to dynamic prices, particularly for perishable goods, using a number of variables, such as income, demand and price. The main factors that influence stochastic behavior of prices in car market supply chains are the focus of the analysis. It also includes the appropriate parameters to include in a dynamic optimization-pricing supply chain problem and a discussion of how businesses can efficiently optimize the pricing problem in a stochastic market situation.
Economic Analysis of Packaging Systems
(North Dakota State University, 2011) Biradar, Vaibhav Mahadev
Packaging has a significant impact on the efficiency and effectiveness of the supply chain, where improvement can be achieved through the development and selection of an appropriate packaging system. One way to explore this is through the development and use of mathematical models that facilitate economic analysis of packaging systems. Recently, one of the most remarkable trends in logistics is the extensive use of returnable or reusable containers. Returnable container systems have increasingly been introduced in various industries to take advantages of cost savings, but it is very crucial to ensure that a reusable packaging system is an economical packaging choice. In this thesis, an extensive study of an economic analysis of disposable, recyclable, and reusable packaging systems is conducted. This includes identification of significant cost factors and variables involved in the management of disposable, recyclable and reusable packaging systems, and formulation of a mathematical model to compare total cost of packaging systems. The developed mathematical model can be used to choose the most economical packaging system for industries. The linear programming (LP) method is used to develop the mathematical model. The various new factors such as the collapsible ratio of recyclable, disposable and reusable packages have been introduced for the first time in the economic analysis of the packaging systems. The developed mathematical model can be used for a range of industries and for different industry scenarios. The packaging system information of Toyota assembly plant is used for the validation of a mathematical model. The obtained results are compared with previous research based on the same data set and results found in concert with the finding of previous research which validate the model.
Impact of Integrating Zone Bypass Conveyor on the Performance of a Pick-To-Light Order Picking System
(North Dakota State University, 2012) Xu, Xia
This thesis investigates the impact of integrating Zone Bypass (ZBP) conveyor to a Pick-To-Light (PTL) order picking system. This integration results in a new system (PTL+Z), which could be helpful to achieve higher levels of productivity in warehousing operations. Two options have been proposed to improve the current PTL system productivity. One is to adapt the ZBP conveyor, which will help each order to bypass unnecessary zones with nothing to pick. Another one is to better plan stock keeping units (SKU) assignment by applying level loading assignment. Mathematical models are developed to evaluate system throughput of PTL system with random assignment (PTL/R), PTL system with level loading assignment (PTL/L), PTL+Z system with random assignment (PTL+Z/R), and PTL+Z system with level loading assignment (PTL+Z/L). Simulation models are validated to test the reliability of mathematical models. Also, economic analysis is developed in term of payback period for decision purpose.
Integration of Simulation and DEA to Determine the Most Efficient Patient Appointment Scheduling Model for a Specific Clinic Setting
(North Dakota State University, 2011) Aslani, Nazanin
This study develops a method to determine the most efficient scheduling model for a specific clinic setting. The appointment scheduling system assigns clinics' timeslots to incoming requests. There are three major scheduling models: centralized scheduling model (CSM), decentralized scheduling model (DSM) and hybrid scheduling model (HSM). In order to schedule multiple appointments, CSM involves one scheduler, DSM involves all the schedulers of individual clinics and HSM combines CSM and DSM. Clinic settings are different in terms of important factors such as randomness of appointment arrival and proportion of multiple appointments. Scheduling systems operate inefficiently if there is not an appropriate match between scheduling models and clinic settings to provide balance between indicators of efficiency. A procedure is developed to determine the most efficient scheduling model by the integrated contribution of simulation and Data Envelopment Analysis (DEA). A case study serves as a guide to use and as proof for the validity of the developed procedure.
Moisture Sensitivity of PLA/PBS Blends During Ultrasonic Welding and Fused Deposition Modeling
(North Dakota State University, 2021) Quader, Raihan
Moisture absorption into hygroscopic/hydrophilic materials used in fused deposition modeling (FDM) and ultrasonic welding (USW) can diminish desired mechanical properties. Sensitivity to moisture is dependent on material properties and environmental factors and needs characterization. In this thesis, moisture sensitivity of PLA filaments and PLA/PBS blended filaments was characterized in FDM printed ASTM test samples post-conditioning the filaments at different relative humidity levels. Tensile strength decreased with increase in moisture content. Parts made with PLA 4043D, PLA/PBS 75/25 filaments were most sensitive to moisture. Investigation of tensile properties of parts made with PLA filaments exposed to room temperature and humidity conditions for three months showed a more significant decrease. Moisture sensitivity of PLA, PBS, and PLA/PBS 25/75 blend characterized for USW using injection-molded industrial standard test parts (ISTeP) showed a downward trend in weld strength for 100% PLA and PLA/PBS 25/75 while 100% PBS was significantly affected at high moisture conditions.
Molecular Dynamics Simulation of Nano-Indentation Process of Silicon: Effects of Initial Temperature and Grain Size
(North Dakota State University, 2014) Wang, Yachao
In this study, a comprehensive investigation on nano-scale indentation of monocrystal and polycrystalline silicon is carried out by adopting molecular dynamic (MD) simulation. Five levels of initial temperature (30K, 100K, 300K, 500K and 700K) are configured in this study and the simulation results reveal the amount of bct-5 silicon atoms at the maximum indentation position is not significantly affected by the initial temperature, substantially less ß-silicon atoms are observed with higher temperatures. The temperature effect on the unloading process is also discussed. Meanwhile, indentation force curves for polycrystalline silicon (grain size ranging from 6.45 nm to 20.48 nm) and single crystalline silicon is compared. The result shows that the normal Hall-Petch effect is not seen in the nano-indentation process of silicon. The grain boundary increases local stress during the indentation process and results in less formation of ß-silicon phase, but it hardly affects the formation of bct-5 silicon.
Multiresponse Optimization Methodology Considering Related Quality Characteristics
(North Dakota State University, 2011) Thambidorai, Ganesh
Engineering problems often involve many conflicting quality characteristics that must be optimized simultaneously. Engineers are required to select suitable design parameter values which provide better trade-off among all quality characteristics. Multiresponse optimization is one of the most essential tools for solving engineering problems involving multiple quality characteristics. Optimizing several quality characteristics when the quality characteristics are correlated makes the optimization process more complex. The aim of this research is to evaluate the performance of several existing multiresponse optimization methods and investigate their capabilities in dealing with correlated quality characteristics. This study also investigates the impact of uncertainty in terms of input parameter selection. A new multi-response optimization approach has been proposed for solving correlated quality characteristics. The proposed approach is compared with the existing methods and found more robust in terms dealing with uncertainty in target selection. The comparative study and application of the proposed approach is demonstrated by considering two examples from the literature having correlated quality characteristics.
Reliability Estimation Considering Customer Usage Rate Profile and Warranty Claims
(North Dakota State University, 2014) Limon, Shah Mohammad
Providing more realistic reliability prediction based on small proportion of failed population or test data has always been a challenging task. Manufacturers rely heavily on reliability prediction for designing warranty plan. Further, to predict warranty claims for the remaining warranty period, it is important to have more realistic reliability assessment by considering a larger proportion of the population or the maximum possible information on the remaining population. However, generally this information is not readily available and is very difficult to gather on the scattered population. In this work, we propose to use customer usage rate profile to generate censored usage data on the remaining population that do not have any failure and warranty claim yet. We intend to use field data available such as warranty claims, field failures, recall data, and maintenance data to develop usage rate profile and subsequently estimate censored usage time. Finally, reliability estimation methodology is developed considering both censored data and field failure data to provide more reasonable reliability prediction for the remaining warranty period. The proposed methodology is demonstrated considering real life data from a big manufacturing company.
Solder Joint Reliability: A Unified Thermo-Mechanical Model Approach
(North Dakota State University, 2014) Advani, Gurmukh Hiro
Due to an unprecedented pervasiveness of electronics in high performance applications, the dependability of mission critical equipment and systems, often solely depends on the reliability of underlying embedded electronic sub-systems. This includes reliability of the solder joints which are subject to fatigue failure over time in harsh operating environments replete with thermo-mechanical stresses. Fatigue behavior of the solder joints has been previously studied under the separate domains of microstructure evolution and non-linear plastic deformations. The proposed study captures the underlying physics of failure mechanisms to model the failure initiation and degradation phases to obtain a unified model characterizing the overall fatigue behavior over the two phases. The model development is followed by reliability analysis which takes into account the individual phases to establish the conditional relationship for a unified reliability model. The reliability analysis has been attempted using both the failure time and the damage accumulation approaches.
Study and Analysis of Automated Order Picking Systems
(North Dakota State University, 2012) Ambati, Akhilesh Chandra
Order picking is an essential part of order processing in warehousing and distribution operations and can be performed using manual, automated, or semi-automated systems. This thesis analyzes two automated systems, which include carousel and AS/RS (automated storage and retrieval system). The main goal of this research is to develop mathematical models to compare the performance of both systems under random and class-based storage assignments. Simulation models are used to validate the reliability of mathematical models. The outputs of mathematical and simulation models are consistent indicating carousel system with class-based assignment has the highest throughput. Economic analysis is used to estimate the payback periods required to convert from manual to AS/RS and carousel systems. The economic analysis shows that converting from manual to AS/RS with class-based assignment has the shortest payback period.
A Study on the Impact of Patient Centered Medical Home (PCMH) Implementation on Nursing Work Practice
(North Dakota State University, 2012) Shinde, Nikhil Vijay
Primary care and nursing are important components of the U.S. healthcare system and are facing challenges of quality, access, cost, time spent and inefficiencies of clinical activities. Patient Centered Medical Home (PCMH) is a newly developed care model which has the potential to overcome these challenges. The present study uses a questionnaire approach to find the impact PCMH implementation may have on nursing practice and subsequently primary care. Analysis of the data collected from the questionnaire revealed some surprising results about the nursing practice. For example nurses spend less time on direct care and more time on indirect care and documentation. The nursing demand in terms of Full Time Equivalent (FTE) for nurses decreases. The future demand for nurses (not in FTE) shows an increase after PCMH implementation. The satisfaction level and overall health of patients, patient readmission, job satisfaction of nurses and department productivity shows improvement after PCMH implementation.
Total Quality Management in Higher Education: A Soft Factor Approach Based on Faculty Satisfaction
(North Dakota State University, 2021) Singh, Samrat
The literature review showed very few organization-wide Total Quality Management (TQM) implementations and mixed opinions regarding its compatibility in Higher Education Institutions (HEIs). Considering the human-centric nature of HEIs this study investigated the interrelationship between the Soft TQM Factors, Faculty Satisfaction, and Student Success. A survey was designed to assess respondents’ perceptions regarding the implementation of Soft TQM Factors and satisfaction among faculty. Analysis of the responses revealed a clear positive relationship between Soft TQM Factors and Faculty Satisfaction. Moreover, Faculty Satisfaction was found to be associated with one of the measures of Student Success, the Graduation Rate. Thus, this study validates the significance of a Soft Factor approach of TQM implementation that concentrates on human-centric factors to enhance Faculty Satisfaction, which may, in turn, foster greater Student Success. The study also yielded a valid survey tool for assessing the implementation of Soft TQM Factors and Faculty Satisfaction in HEIs.
Transparent and Crack-Free Silica Aerogels
(North Dakota State University, 2012) Athmuri, Kalyan Ram
The process of making silica aerogels has been studied in detail over the past two decades due to its usage in a wide range of low end applications such as thermal insulators, supercapacitors etc., as well as high end applications like particle physics, space explorations. These applications call for control over the properties of aerogels, such as their transparency, density, porosity, pore size, and integrity. However, despite all the past research, controlling properties of aerogels is still not a fully developed science, a lot more research needs to be done. The literature on silica aerogels does not cover the study of the relation between transparency and cracks in aerogels – which can be a key factor in making aerogels for many applications. Hence, optimization of the transparency and integrity of the aerogels in order to obtain high transparency and low cracks was attempted in this thesis.
Two-Echelon Vehicle Routing Problems Using Unmanned Autonomous Vehicles
(North Dakota State University, 2017) Rahman, Md Mahbubar
In this thesis, we investigate new multi-echelon vehicle routing problems for logistics operations using unmanned autonomous vehicles. This can provide immediate tangible outcomes, especially in high-demand areas that are otherwise difficult or costly to serve. This type of problem differs from the commonly used multi-echelon supply chain management systems in that here there exist no intermediate facilities that consolidate/separate products for delivery; instead all decisions are made on a per-vehicle basis. We describe here how we can obtain the necessary parameters (data collection) to evaluate the performance of such multi-echelon systems. We also provide three mathematical formulations based on different assumptions and case scenarios. We then study the differences between the three models in practice, as far as routing cost and duration of operations are concerned. We finally show that there are savings to be had by properly employing unmanned vehicles for logistics operations.
Winter Road Maintenance System Design for Snow Plowing
(North Dakota State University, 2010) Kayabas, Poyraz
Winter road maintenance is critical to ensuring safety and mobility of transportation systems in regions with heavy snowfall. Winter road maintenance system design involves several inter-related decision making problems for different operations that are often performed with expensive and limited resources. This study involves developing an integrated solution methodology for depot location selection, district design, and vehicle routing problems for winter road maintenance system design in the context of snow plowing. The methodology allows decision makers to evaluate and compare different system alternatives based on a number of service level related system design criteria. The solution methodology is illustrated using the example of the road network of the Fargo District of North Dakota's transportation system. Results indicate that the methodology can be used as a decision making support tool for planning winter road maintenance operations.

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