The concept of construction productivity began in the early 20th century with a series of time and motion studies to improve bricklaying operations. A substantial number of subsequent studies focused on repetitive tasks and automation of the manufacturing operations and subsequently benefited manufacturing more than the construction industry. There has been a lack of studies for productivity improvement in the construction industry. Building upon the available body of knowledge as it related to productivity of manufacturing and construction industries, this study focused on developing a project improvement system for effective management of construction projects. Development of the system included a review of literature, where an inventory of productivity related factors was found and interpolated into a primary productivity evaluation checklist. A survey of construction practitioners was conducted to rank and determine the degree of influence of various factors on construction productivity. A field study gathered information for the refinement of the primary productivity evaluation checklist. The review of literature, together with the findings of survey and field study, led to the development of the Project Improvement System (PIS). Finally, the PIS was tested and evaluated in a case study of a construction project to ensure its workability, suitability, and influence. Out of 36 productivity factors gathered from the literature, the survey identified 30 factors as high, 4 factors as moderate, and 2 factors as low with respect to their degree of influence on productivity. This information provided guidance for the field study to refine the primary productivity evaluation checklist. The survey revealed that executives, project managers, and superintendents of general contracting firms have similar perceptions of the degree of influence of productivity factors in construction and view productivity as a concept within their reach and control. Application of the system to a case study resulted in improvement of the rates of productivity of various construction tasks after application of PIS and a projected savings of 4.27% in the labor cost. The findings of this study imply that PIS is an effective tool for project managers to improve productivity and increase the bottom-line of construction projects.

The electrodeposition of nickel-rhenium alloys from Ni(II) and Re(VII) solution was studies in an aqueous acidic solution. Different plating current density and pH have been carried out, and the effect of them on the composition of the deposited Ni-Re alloy was studied. Wavelength-dispersive spectrometer (WDS) was used to measure the composition of Ni-Re alloy. The thermal stability of nickel-rhenium alloy system has been investigated. Differential scanning calorimetry (DSC) tests have been conducted for the electroplated Ni-Re samples in order to find the possible heating initiated interactions at elevated temperatures. To investigate the thermal stability of Ni-Re alloys, the samples were annealed under nitrogen environment for 90 minutes at 280°C, 350°C, 600°C and 900°C. Transmission electron microscopy (TEM) was used to exam the microstructures of Ni-Re alloy samples as-deposited and heat-treated. The results show that the as-deposited Ni-Re material grain size for this plating condition is around 380nm. The results also show that after heating at 600°C for 90 minutes, there was no significant grain growth observed. The microhardness and nanohardness of Ni-Re alloy were also studied with as-deposited and heat-treated samples. Tensile strength was carried out by dynamic mechanical analyzer (DMA) at room temperature and elevated temperature of 400°C. This research demonstrated a well developed, thermally stable and mechanically sound material system for LIGA/MEMS high temperature robust applications.

The objective of this research was to develop and validate a generalized team task-complexity model and framework by drawing on the literature from various team and task factors grouped into three task-dimensions, which compose task-complexity space and how these affect the task-performance. A number of task typologies have been presented in the teams' literature to better define and understand the critical role of the tasks and the associated team processes. In addition, most of the research work has defined team measures as highly abstract concepts not capable of providing the quantitative comparison of team performances from various domains. This research proposed a model of task-complexity based on different task-characteristics including task-scope, task-coordination and task-uncertainty that provide the capability to quantify different attributes that impact team performance. A multiple linear regression analysis was used to validate the contribution of each task-complexity dimension towards complexity and performance. Analysis of variance was also used to account variance in measurement scales and not to force linear relationship. The results indicate a significant three-way interaction of task-scope, task-coordination and task-uncertainty. Since three-way interaction was significant, all the three task-complexity dimensions were significant and not equally contributing towards team task-performance. Two-way interaction of task-scope and task-coordination was significant when task-uncertainty was negligible. Thus both were not equally contributing towards team task-performance. From effect tests, task-coordination and task-uncertainty were found to be highly significant with relation to task-performance. Though task-scope was not significant, further analysis reveals that it had significant impact on task-performance at its highest level and when task-uncertainty was negligible. Thus explains its inclusion in the three-way interaction. Workload, a subjective team performance measure in team literature, was used for model cross-validation. Results found a significant negative correlation between perceived task-workload and task-performance, thereby validating the model from workload perspective. This study summarizes the different task-characteristics affecting the team task-performance. This study has practical implications in the design and evaluation of collaborative tools and team training. Further research would develop a synthetic collaborative system that would emulate certain complex work environments and enable the collection of team performance data for assessing hypotheses about collaboration.

Musculoskeletal disorders account for 32 percent of work related injuries and illnesses. Extensive studies have been conducted to understand and explore the factors that affect the development of musculoskeletal disorders to provide effective control strategies. One of the most important factors that allow effective control strategies is the biomechanical factors. Among the biomechanical risk factors, exposures to repetitive static and vibratory activities are known to result in musculoskeletal disorders. A ligamentomuscular reflex activity exists in humans and animals to stabilize the knee, shoulder, elbow, ankle joints, and spine. This reflex activity decreases over time when static loading is applied, which leads to joint instability and decreased safety of the spine. However, the recovery process of this reflexive muscle activity to its original state is a complicated phenomenon and the research efforts in this area are limited to a few animal based experiments. Although the recovery process is modeled and known for animals, the process for human muscle recovery is still unknown. This study concentrates on the behavior and recovery of the human lumbar muscle when subjected to static loading. Ten males participated in this study where the electrical activity of their erector-spinae muscle for two different lumbar levels was recorded for twenty minutes of loading and three hours of recovery period to observe and model the muscle behavior. The behavior of recovery was modeled using a bi-exponential structure previously developed for animal experiments. However, the analysis of the EMG showed that the sitting task during rest periods created additional static loading on the lower back. The effects of this task were introduced to the model by adding a third exponential component referred to as the daily activity factor. Overall, the results support the previous findings about the behavior of the lower back muscles that were developed by animal experiments. However, the mathematical description of the phenomenon is modified by taking the daily activity factor into account. Understanding the time periods and phases for the recovery is essential, since a better understanding of the phenomenon can lead to optimal design of work/rest periods in occupational as well as sports activities.

UV lithography of thick photoresist is widely used in microelectromechanical systems (MEMS) and micro-optoelectromechanical systems (MOEMS). SU-8 is a typical negative tone thick photoresist for micro systems, and can be used for both structural material and pattern transfer. This dissertation presents an effort to comprehensively study these important subjects. The first part, and the most fundamental part of this dissertation concentrated on the numerical analysis and experimental study of the wavelength dependent absorbance of SU-8 and the diffraction effects on the sidewall profiles of the microstructures made using UV lithography of SU-8. This study has laid the foundation for all the designs and analysis for the BioMEMS and Micro-optic components and systems using UV lithography of SU-8 in the following chapters of the dissertation. After a full discussion of UV lithography of SU-8, the applications of SU-8 in BioMEMS and micro optics were presented in the following areas: 1) design, analysis, and molding fabrication of biodegradable PLGA microstructures for implanted drug delivery application; 2) design, fabrication, and test of a novel three-dimensional micro mixer/reactor based on arrays of spatially impinging micro-jets; 3) design, analysis, fabrication, and test of a novel new type of truly three-dimensional hydro-focusing unit for flow cytometry applications based on SU-8; 4) Study on a new technology to fabricate out-of-plane pre-aligned microlens and microlens array, and the application of the microlens in a fiber bundle coupler. Finally, a new negative tone thick photoresist based on the composition of EPON resins 165 and 154 were introduced. The synthesis, physical properties, and UV-lithography properties of this new photoresist have been completed. The experimental results have proved it can be a better alternative to SU-8 and can be used in various MEMS and MOEMS applications. Most of the contents have been published or accepted for publications in technical journals or international conferences. Two US patent applications are pending and two more disclosures have been filed for the new technologies presented in this dissertation. There are obviously more work to be done in this promising area and these are presented in the section for future work.

Asphalt mixtures are particulate composite materials consisting of uniformly distributed mineral aggregates, asphalt binder and air voids. Mixtures of asphalt binder and filler, also called mastics, are often assumed to behave as simple viscoelastic materials, where the binders are stiffened by the filler. Because the workability and performance of bituminous mixes are known to be affected by the filler-asphalt mixture (or mastic) properties, this study is intended for performing rheological tests on asphalt binder and mastics and use the results in order to estimate performance parameters of asphalt mixture. The present work uses the PG64-22 asphalt binder test data initially to predict mastics' performance parameters - shear modulus (G*) and accumulated permanent shear strain (γ_acc) and then same properties for asphalt mixtures, in order to find a correlation between the three materials. Mastics were obtained by mixing the PG64-22 asphalt with three types of filler - donna fill, limestone, and granite - in five different percentages by volume - 5, 10, 15, 20, and 30%. The asphalt mixtures contained granite aggregate, 6% air voids content and five asphalt contents - 3% through 7%. Binder and mastics were tested at three temperatures (46°, 55°, and 64°C) using a dynamic shear rheometer (DSR), while the mixtures were tested at two temperatures (55° and 64°C) using the Superpave shear tester. Newly developed Hirsch model was used for estimating the shear moduli of asphalt mastics and mixtures, while for estimating the accumulated permanent shear strain a semi-empirical equation developed by Shenoy was used. Both estimations have been performed by using the shear modulus of the binder obtained from the DSR. The binder, mastics, and mixtures rheological data were generated using the appropriate equipment for each material, under identical conditions of measurement, thus making it possible to identify a correlation between the materials. There was a good agreement between the measured and estimated values using the two methods (Hirsch and Shenoy), with Pearson correlation parameters (R²) being over 0.90 or better.

Polymer based micro-transducers have many advantages over the traditional silicon based micro-transducers, such as easy integration with metal structures, design flexibility, and low fabrication costs. The characteristics of micro-transducers include converting electrical signals to/from mechanical response, the ability to sustain loading, sensitivity to external excitation, and etc. Some of the difficulties in realizing these characteristics include: characterizing material mechanical properties, techniques for producing electrically conductive polymer structures, and reliable fabrication procedures. In this dissertation, research addressing these difficulties is presented. The developed techniques are demonstrated in the design and fabrication of a SU-8 polymer based comb-drive micro-actuator. The micro-actuator used SU-8 polymer as the main structural material and gold coating film for realizing electrical conduction. It was fabricated with multi-layer, multi-step UV-lithography technology and metallized with titled E-beam deposition and selectively electroless plating techniques. The adhesion properties between metallic surface and SU-8 polymer were measured firstly. After comparing different metals, Au was chosen as the base material for electroplating for its good adhesion to SU-8. Customized micro-fracture toughness measurement procedure was then designed based on ASTM standards to measure the fracture toughness of Ni micro-structures. The difficulties in micro-fabrication were then addressed. Two different approaches were evaluated for fabricating the SU-8 micro-structure: (1) multilayer processing using modified SU-8 with reduced PAG; (2) multilayer processing using normal SU-8 with copper as sacrificial layer. The second method was shown more reliable. The polymer structures were surface metallized using two methods: (1) titled E-beam deposition; (2) selectively electroless plating. The latter was proven to be more suitable for high aspect ratio sidewalls. The proper UV exposure dosage, duration, and other parameters were also established. A novel structural design of comb drive micro-actuator was studied using analytical and finite element analysis. The design was realized with the developed fabrication technologies. Finally, the resulted micro-actuators were tested to prove the feasibility of the design and fabrication.

This research deals with a supply chain system where the production or manufacturing facility operates under a just-in-time (JIT) environment, and the facility consists of raw material suppliers, manufacturers, and retailers where inventory of raw materials, work-in-process, and finished goods are involved, respectively. This work considers that the production of finished goods in one cycle starts just after the production or uptime in preceding cycle to minimize the idle time of the facility. Considering this scenario, inventory models are developed for different delivery situations: (a) perfect matching condition where no finished good remains after the shipments and (b) imperfect matching condition where some finished goods remain after the shipments. In this research, the problems are categorized as integer and mixed integer non-linear programming problems which are solved to find optimum number of orders and shipments, optimum production quantity, and minimum system cost. Moreover, multi-supplier and multi-buyer operations, where raw materials are ordered from different suppliers and finished goods are delivered to different customers, are considered. In addition to these problems, a single facility lot-sizing model is applied in perfect and imperfect matching cases, and, multi-supplier and multi-buyer case, to concentrate on more practical supply chain environments. All the problems described in this research are non-convex functions for which the closed form solutions are cumbersome. Therefore, the heuristic solutions are developed to find the optimal lot-sizing techniques. Additionally, the multi-supplier and multi-buyer problem is solved with the help of integer approximation and the divide and conquer rule. The solutions are tested through numerical examples. Furthermore, the sensitivity analyses are performed to observe the variations of the different cost functions. Also, this research proposes an alternate delivery schedule of finished product supply, for which both manufacturers and buyers will be benefited economically. The production and supply chain management play a significant role for the necessary amounts of materials and parts arrive at the proper time and place. With the models obtained in this research, managers can quickly respond to consumers' demand by determining the right policies to order raw materials, to manage their production schedule efficiently and to deliver finished goods just-in-time.

This dissertation can be divided into four parts. In part I (Chapter 2), the diffusion controlled growth of multiple compound phases is studied with the nonlinear Kirkendall effect included. This part analyzes the growth of N compound phases. The method of finding intrinsic diffusion coefficients from only the positions of interfaces is found for two layers. In addition, the asymptotic analysis valid for small concentration gradients is applied to the multi-foil method of measuring intrinsic diffusion coefficients and yields an analytic solution for the displacement curve. A bounded solid film on a substrate can breakup from the edge into islands to reduce the surface energy. Part II (Chapter 3) studies the three-dimensional linear stability of a retracting film profile. An unstable mode of perturbation is found. The perturbed film profile is wavy along the film edge which can initiate the formation of fingers seen in experiments. The wavelength of the fastest growing perturbation agrees with the distance between two adjacent islands observed in experiments. Part III (Chapter 4) studies the linear stability of square or triangular wires with azimuthal surface energy anisotropy. The growth rate of a normal mode is governed by an eigenvalue problem, which is solved numerically by a pseudospectral method. The fundamental and first modes, which correspond to varicose(sausage) and helical modes, are unstable for long wavelengths. The varicose mode has the highest growth rate for the range of parameters investigated. The maximum growth rate increases with anisotropy, implying that the anisotropy is destabilizing. An asymptotic solution is derived in the limit of zero anisotropy, and it agrees with the numerical solutions. The results obtained here for wires also apply to channels. Part IV (Chapter 5) investigates Rayleighs instability of nano wires by classic molecular dynamic simulations. The melting point of nanowires with different radii is found by calculating the caloric curve and mean square displacement curve. Liquid and solid nano-wires with different radii are simulated. It shows that liquid wires breakup following Rayleighs instability criterion, whereas solid wires dont.

Software testing is a process to detect faults in the completeness and quality of developed computer software. Testing is a key process in assuring quality by identifying defects in software, and possibly fixing them, before it is delivered to end-users. A major decision to make during this software testing is, to determine whether to continue testing and eventually releasing the software, or when to stop the test and crash it. Such a decision needs to be made to optimally balance the tradeoff between the cost of development and the reliability of the software. In this paper, a new optimal strategy is developed based on a conditional non-homogeneous Poisson process (Conditional-NHPP) on a continuous time horizon to determine when the optimal time is to release or crash the software.