Canada’s workforce, as well as many other countries, is continuing to age as the baby boomer generation (those born between 1946 and 1964) ages and are remaining in the workforce longer. The number of older workers is estimated to double within the next 10 years (Perry 2010). With increased age, there are a number of factors that could influence worker performance and risk of injury. For example, aging is associated with decreased strength and cardiovascular fitness. However, it is unknown whether a worker’s estimates of how much they can safely lift (based on an approach called psychophysics, which is often used in the design of manual materials handling tasks) is lower for older compared to younger workers. The primary goal of this thesis was to test the hypothesis that psychophysical estimates of maximum acceptable forces would be lower for older workers than younger workers during selected lifting tasks. The secondary goal was to measure a host of variables to provide insights into what factors (e.g. kinematic, strength, cardiovascular) might be influencing potential age-related differences. The experimental testing protocol used a psychophysical approach to identify the maximum acceptable mass of an object during several lifting tasks. Participants comprised a total of 24 female workers (12 older (50+ years old) and 12 younger (20-30 years old)). The primary outcome of interest was the maximum acceptable weight of lift (MAWL) for an 8 hour work day that would allow each participant to ‘work as hard as they can without straining themselves, or becoming unusually tired, weakened, overheated, or out of breath’ (Snook and Ciriello 1991). The participants completed four lifting tasks: floor-to-knuckle height (1 lift/9s and 1 lift/2 min) and knuckle-to-shoulder height (1 lift/2 min and 1 lift/8 hr) by adding or removing lead shot to a lifting box. Tasks were 30 minute in duration; participants could adjust the load mass at any time during the trial. The dependent variables collected were the MAWL (the load mass at the end of the trial), maximum sagittal plane joint angles of the shoulder, hip and knee, overall and body part specific ratings of perceived exertion, and heart rate. Older workers selected MAWL values that were significantly lower (by approximately 24%) than their younger counterparts. These age-related differences were more prevalent for tasks which were constrained by strength (i.e. low frequency) compared to those with large cardiovascular requirements (i.e. high frequency). The only significant difference in the sagittal plane joint flexion angle was for the right hip during the 1 lift/2 min from floor-to-knuckle height lifting task, characterized by 34.4 degree decrease hip angle (more flexed) for the older workers. There were also no significant age-related differences in overall ratings of perceived exertion. The only body part-specific rating of perceived exertion with a significant age-related difference was for the knees, with the younger workers reporting the tasks more taxing on this joint than the older workers. Although there were no age-related differences in absolute heart rate values, the older workers were at a significantly higher percentage of their maximum heart rate. The results of this work suggest there is value in continued research probing whether current ergonomic and work design guidelines need to be updated to accommodate the aging working population. According to the results presented in this study, the current approaches often employed during the design of manual materials handling tasks (i.e. incorporating the loads that 75% of females could perform based on the Snook and Ciriello tables (1991) may not be sufficiently protective for older female workers in the workplace.

This thesis presents the development of a model for analyzing the design of an automated live-bird transfer system (LBTS) developed at Georgia Tech. One of the most fundamental tasks in the automated transferring is to design and control a grasping system that is capable of accommodating a specified range of objects without causing damage. However, unlike grasping in robotic research that focuses on dexterous manipulation of a single object, repetitive transfer of live objects in a production line requires continuous grasping at high-speed. This thesis research investigates the use of rotating fingers (capable of undergoing large deflections) to cradle live birds on a moving conveyor for subsequent handling. As compared to fingers with multiple active joints, flexible fingers have many merits, for they are lightweight and have no relative individually moving parts. Their ability to accommodate a limited range of varying sizes, shapes, and the natural reactions of some objects makes rubber fingers an attractive candidate for use as graspers in a high-speed production setting. However, the advantages of flexible fingers are seldom exploited for grasping because of the complex analysis involved in the design. In order to reduce the number of birds and hardware/software design configurations to be tested, a good understanding of the object dynamics throughout the grasping process is necessary. In this thesis, a quasi-static model has been developed for predicting the contact force between a moving object and a rotating finger. The model has been validated with the experimentally measured data and the computed results using finite element (FE) methods. Finally, an illustrative application of the validated model has been demonstrated in the design of a rotating hand used in the automated LBTS. As illustrated in the simulation results, the computed contact forces can be used as a basis for predicting potential bruises on the bird that may be caused by the rotating fingers. The analytical model presented in this paper provides a rational basis for optimizing the design of the grasping system and developing a controller for a high-speed transfer system. It is expected that the analysis presented here can be readily extended to other dynamic systems involving the use of flexible beams.

This thesis proposes a computationally effective analytical approach to automated material handling system (AMHS) performance modeling for a simple closed loop AMHS, such as is typical in supporting a 300mm wafer fab bay. Discrete-event simulation can produce accurate assessments of the production performance, including the contribution by the AMHS. However, the corresponding simulation models are both expensive and time-consuming to construct, and require long execution times to produce statistically valid estimates. These attributes render simulation ineffective as a decision support tool in the early phase of system design, where requirements and configurations are likely to change often. We propose an alternative model that estimates the AMHS performance considering the possibility of vehicle-blocking. A probabilistic model is developed, based on a detailed description of AMHS operations, and the system is analyzed as an extended Markov chain. The model tracks the operations of all the vehicles on the closed-loop considering the possibility of vehicle-blocking. The resulting large-scale model provided reasonably accurate performance estimates; however, it presented some computational challenges. These computational challenges motivated the development of a second model that also analyzes the system as an extended Markov chain but with a much reduced state space because the model tracks the movement of a single vehicle in the system with additional assumptions on vehicle-blocking. Neither model is a conventional Markov Chain because they combine the conventional Markov Chain analysis of the AMHS operations with additional constraints on AMHS stability and vehicle-blocking that are necessary to provide a unique solution to the steady-state behavior of the AMHS. Based on the throughput capacity model, an approach is developed to approximate the expected response time of the AMHS to move requests. The expected response times are important to measure the performance of the AMHS and for estimating the required queue capacity at each pick-up station. The derivation is not straightforward and especially complicated for multi-vehicle systems. The approximation relies on the assumption that the response time is a function of the distribution of the vehicles along the tracks and the expected length of the path from every possible location to the move request location.

<p>Packaging has a major impact on the activities performed in a logistical value chain. Packaging can improve or decrease the efficiency of the outbound logistics process. It is therefore important to consider the activities and the value that they add to the overall process. ROL International is a Swedish store interior manufacturer that design, produce and distribute their products on a global basis. One of their basic products is the shelf concept. ROL wants to improve their efficiency and consider a change in the packaging method for the shelf concept. Two alternative packaging methods have been suggested and ROL want to know if either of the two alternatives would result in increased efficiency.</p><p>The purpose of this report is to evaluate the two packaging alternatives and their impact on the activities connected to the outbound logistics at ROL International.</p><p>Since the study was conducted at request from ROL International, it is considered as a qualitative single case study. Observations, mainly at ROL’s warehouse but also through an observation at one customer’s premises, were used for determination of the activities included throughout the studied process. In addition to the observations, interviews were conducted with key persons concerned with the effects of a change in packaging method. Secondary data in form of order and shelf statistics were important for the study due to its impact on the frequency in which the studied activities are performed.</p><p>The study found that neither of the two suggested packaging alternatives are suitable for implementation in the present situation. This is mainly because of the increase in activities needed to perform the packaging of shelves, which would result in increased cost that cannot be justified through enhanced customer service and higher quality. More-over, the study also found that the current process for picking customer orders are ineffi-cient and might require a restructuring of the warehouse operation in order to become more efficient.</p>

Thesis--Universität Ulm, 2006. / Includes bibliographical references.

Canada’s workforce, as well as many other countries, is continuing to age as the baby boomer generation (those born between 1946 and 1964) ages and are remaining in the workforce longer. The number of older workers is estimated to double within the next 10 years (Perry 2010). With increased age, there are a number of factors that could influence worker performance and risk of injury. For example, aging is associated with decreased strength and cardiovascular fitness. However, it is unknown whether a worker’s estimates of how much they can safely lift (based on an approach called psychophysics, which is often used in the design of manual materials handling tasks) is lower for older compared to younger workers. The primary goal of this thesis was to test the hypothesis that psychophysical estimates of maximum acceptable forces would be lower for older workers than younger workers during selected lifting tasks. The secondary goal was to measure a host of variables to provide insights into what factors (e.g. kinematic, strength, cardiovascular) might be influencing potential age-related differences. The experimental testing protocol used a psychophysical approach to identify the maximum acceptable mass of an object during several lifting tasks. Participants comprised a total of 24 female workers (12 older (50+ years old) and 12 younger (20-30 years old)). The primary outcome of interest was the maximum acceptable weight of lift (MAWL) for an 8 hour work day that would allow each participant to ‘work as hard as they can without straining themselves, or becoming unusually tired, weakened, overheated, or out of breath’ (Snook and Ciriello 1991). The participants completed four lifting tasks: floor-to-knuckle height (1 lift/9s and 1 lift/2 min) and knuckle-to-shoulder height (1 lift/2 min and 1 lift/8 hr) by adding or removing lead shot to a lifting box. Tasks were 30 minute in duration; participants could adjust the load mass at any time during the trial. The dependent variables collected were the MAWL (the load mass at the end of the trial), maximum sagittal plane joint angles of the shoulder, hip and knee, overall and body part specific ratings of perceived exertion, and heart rate. Older workers selected MAWL values that were significantly lower (by approximately 24%) than their younger counterparts. These age-related differences were more prevalent for tasks which were constrained by strength (i.e. low frequency) compared to those with large cardiovascular requirements (i.e. high frequency). The only significant difference in the sagittal plane joint flexion angle was for the right hip during the 1 lift/2 min from floor-to-knuckle height lifting task, characterized by 34.4 degree decrease hip angle (more flexed) for the older workers. There were also no significant age-related differences in overall ratings of perceived exertion. The only body part-specific rating of perceived exertion with a significant age-related difference was for the knees, with the younger workers reporting the tasks more taxing on this joint than the older workers. Although there were no age-related differences in absolute heart rate values, the older workers were at a significantly higher percentage of their maximum heart rate. The results of this work suggest there is value in continued research probing whether current ergonomic and work design guidelines need to be updated to accommodate the aging working population. According to the results presented in this study, the current approaches often employed during the design of manual materials handling tasks (i.e. incorporating the loads that 75% of females could perform based on the Snook and Ciriello tables (1991) may not be sufficiently protective for older female workers in the workplace.

Thesis (Ph. D.)--Rutgers University, 2007. / Graduate Program in Industrial and Systems Engineering. Includes bibliographical references (p. 132-138).

Thesis (Ph. D.)--Ohio State University, 2007. / Full text release at OhioLINK's ETD Center delayed at author's request

Thesis (MSc)--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: This study was initiated in October 2004 when Vizier Systems (Pty) Ltd approached the Department of Industrial Engineering at the University of Stellenbosch with a concept. They proposed that a fruit packing line be represented as a series of unit operations and suggested that the concept could be used to create a generic model that can be used to represent any packing line. After further discussions with Vizier about the concept and their reasons for requiring a generic model, a formal client requirement was formulated. It was decided that the generic modelling concept had to be tested in the citrus industry. Modelling theory was investigated and a generic modelling methodology was formulated by adapting an existing modelling methodology. The first few steps of the developed methodology led to industry data being gathered and several role-players in the citrus export industry being visited. An analysis of the data enabled the development of the necessary techniques to do distribution estimation and forecasting of the system input, which is fruit. The various processes were grouped into generic groups and detailed capacity calculations were developed for each process. The fruit parameter estimation techniques and capacity calculations were integrated into a five step modelling procedure. Once the generic model was set up to represent a specific packing line, the modelling procedure provided optimum flow rates, equipment setups and personnel allocations for defined production runs. The modelling procedure was then translated into a computer model. This allowed a complete capacity analysis of a packing line by incrementally varying the characteristics of the fruit input. The developed generic model was validated by comparing its predictions to the results of two production runs at an existing packing line. It was found that the generic model is able to adequately represent the packing line and that the fruit inputs and outputs can be accurately estimated. The concept proposed by Vizier, that a packing line can be generically modelled as a series of unit operations, was shown to be valid. / AFRIKAANSE OPSOMMING: Hierdie studie is in Oktober 2004 geïnisieer toe Vizier Systems (Pty) Ltd die Departement van Bedryfsingenieurswese aan die Universiteit van Stellenbosch met ’n konsep genader het. Hulle het aan die hand gedoen dat ’n vrugtepaklyn voorgestel kan word as ’n reeks eenheidsprosesse en dat die konsep gebruik kan word om ’n generiese model te skep om enige vrugtepaklyn te verteenwoordig. Na verdere samesprekings met Vizier oor die konsep en hul redes vir die noodsaaklikheid van ’n generiese model, is ’n formele kliëntebehoefte geformuleer. Daar is besluit dat die generiese modelleringskonsep in die sitrusbedryf getoets gaan word. Modelleringsteorie is ondersoek en ’n generiese modelleringsmetodologie is geformuleer deur ’n bestaande modelleringsmetodologie aan te pas. Die stappe van die ontwikkelde metodologie het gelei tot die insameling van data vanuit die industrie en verskeie rolspelers in die sitrus-uitvoerindustrie is besoek. ’n Analise van die data het die ontwikkeling van die tegnieke moontlik gemaak wat nodig was om verspreidingsberamings en voorspelling van die stelselinset – die vrugte – te doen. Die onderskeie prosesse is gegroepeer in generiese groepe en gedetailleerde kapasiteitsberekeninge is vir elke proses ontwikkel. Die vrugparameter beramingstegnieke en kapasiteitsberekeninge is geïntegreer in ’n vyf-stapmodelleringsprosedure. Nadat die generiese model opgestel is om ’n spesifieke paklyn voor te stel, het die modelleringsprosedure optimum vloeitempo’s, toerustingopstellings en personeeltoedelings vir die spesifieke produksielopie gegee. Die modelleringsprosedure is toe herlei tot ’n rekenaarmodel. Dit het ’n volledige kapasiteitsanalise van die paklyn moontlik gemaak, deur die eienskappe van die vruginset inkrementeel te varieer. Die ontwikkelde generiese model is gestaaf deur sy voorspellings te vergelyk met die resultate van twee produksielopies van ’n bestaande paklyn. Daar is bevind dat die generiese model in staat is om die paklyn voldoende voor te stel en dat dit die vruginsette en -uitsette akkuraat kon beraam. Die geldigheid van die konsep wat voorgestel is deur Vizier, naamlik dat ’n paklyn generies gemodelleer kan word as ’n reeks eenheidsprosesse, is bevestig.

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / Small and medium toilet manufacturing businesses in Peru face significant problems such as low productivity because of a high rate of production losses. To address this issue, the present study proposes the application of a lean manufacturing technique, such as the Poka-Yoke model, which improves the production flow within the company by implementing a transportation cart with a safety system to help reduce material falls during the manufacturing process. The results showed a 24% increase in productivity and reduction in problems of damaged products that did not meet quality standards, thus preventing their subsequent reprocessing. / Revisión por pares