OF THE DISSERTATION ........................................................................... ii ACKNOWLEDGEMENTS ............................................................................................... iv 1 CHAPTER
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Degradation models are normally used to predict the system's failure under condition-based predictive maintenance policies. Repairs or replacements of the system are performed once the degradation level reaches a predetermined... more
Degradation models are normally used to predict the system's failure under condition-based predictive maintenance policies. Repairs or replacements of the system are performed once the degradation level reaches a predetermined threshold level. This results in a significant ...
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Furnaces used in petrochemical industry are usually subject to extreme conditions owing to the constraint of the processes involved. The tubes of such furnaces, re-ferred to as reformer tubes, are arranged vertically in a reduction... more
Furnaces used in petrochemical industry are usually subject to extreme conditions owing to the constraint of the processes involved. The tubes of such furnaces, re-ferred to as reformer tubes, are arranged vertically in a reduction chamber and re-ceive a mixture of ...
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Condition based maintenance (CBM) is a powerful tool for improvement of system reliabil- ity and reduction of system downtime. This research considers CBM under which the system state is peri- odically observed with or without... more
Condition based maintenance (CBM) is a powerful tool for improvement of system reliabil- ity and reduction of system downtime. This research considers CBM under which the system state is peri- odically observed with or without observational error, and maintenance is imperfect. System availability is maximized by determining the optimal maintenance threshold and the time interval between consecutive inspections of the state of the system. The optimal solution can be obtained numerically using a sequen- tial uniform design algorithm.
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Fatigue failures caused by cyclic stresses are commonly modeled by Birnbaum-Saunders (B-S) and Weibull distributions. Sometimes, materials with high cycle fatigue exhibit bimodal failure rates which are difficult to model with Weibull... more
Fatigue failures caused by cyclic stresses are commonly modeled by Birnbaum-Saunders (B-S) and Weibull distributions. Sometimes, materials with high cycle fatigue exhibit bimodal failure rates which are difficult to model with Weibull distribution. The objective of this paper is to investigate a general Birnbaum-Saunders (GB-S) distribution which covers diverse hazard rates such as increasing, upside down, multimodal and others. This paper also utilizes GB-S distribution to model fatigue failure data and validate its performance under different conditions. GB-S-based-ALT model is also developed to provide accurate reliability and lifetime prediction at operating conditions using data from accelerated life testing experiments.
Multiple sensors are commonly used for degradation monitoring of critical components. The degradation indicators derived from these sensors are significantly different in terms of scale and interpretation. Since these indicators reflect... more
Multiple sensors are commonly used for degradation monitoring of critical components. The degradation indicators derived from these sensors are significantly different in terms of scale and interpretation. Since these indicators reflect the same degradation path but have different scales and noise, the fusion of the data corresponding to these indicators is important for the condition monitoring and accurate reliability estimation of the components. In this paper, we develop a unified degradation path that considers statistics-based degradation and physics-based degradation models. We also estimate the reliability of such components. Simulation results show that the unified degradation model approximates the actual degradation path effectively. Additionally, more accurate estimates of reliability are obtained when compared with individual degradation paths.
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In this paper, we present an external pipeline inspection robotic system capable of detecting the surface defects on above-ground pipelines and modeling their degradation. This system consists of two subsystems, the main base and the... more
In this paper, we present an external pipeline inspection robotic system capable of detecting the surface defects on above-ground pipelines and modeling their degradation. This system consists of two subsystems, the main base and the sensing system. The main base is a self-driving autonomous ground vehicle (AGV) equipped with Lidar, acoustic sensors and motor encoders, which can track the pipeline on uneven terrains. The sensing system includes two cameras attached to a C-arm, which rotates around the pipe. The two cameras are placed 180° from each other and can take pictures at 90° intervals, allowing the system to analyze the full 360° of the pipe with only half of the rotation as compared to a single camera system. When the C-arm encounters a flange or support, it retracts off the pipe, moves past the obstacle, and extends back to continue taking images. These images are used for defect detection. The detected defect data is then used for modeling the defect degradation and predi...
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... [11] Simsek D., Cinar C., Yalcinkaya I., On the recursive sequence xn+1 = xn−3 1 + xn−1 , Int. J. Contemp. Math. Sci., 1(10)(2006), 475-480. Elsayed Mohammed Elsayed Mathematics Department Faculty of Science Mansoura University... more
... [11] Simsek D., Cinar C., Yalcinkaya I., On the recursive sequence xn+1 = xn−3 1 + xn−1 , Int. J. Contemp. Math. Sci., 1(10)(2006), 475-480. Elsayed Mohammed Elsayed Mathematics Department Faculty of Science Mansoura University Mansoura 35516, Egypt e-mail ...
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ABSTRACT Abnormal driving behaviors have been used as cues to identify Driving While Intoxicated (DWI) drivers and prevent DWI-related accidents. Currently law enforcement officials rely on visual observation for detecting such behaviors... more
ABSTRACT Abnormal driving behaviors have been used as cues to identify Driving While Intoxicated (DWI) drivers and prevent DWI-related accidents. Currently law enforcement officials rely on visual observation for detecting such behaviors and identify potentially DWI drivers. This approach however, is subject to human error and limited to vehicles in a very small region. To overcome these limitations, we propose to use an Unmanned Aircraft System (UAS) for driving-behavior monitoring to prevent accidents and promote highway safety. A high-resolution optical camera on the UAS is used to capture the movement of vehicles on the road. The vehicle trajectories are tracked from the captured videos to identify the misbehaviors. This allows for a quicker response time from law enforcement. A risk model is also developed for analyzing the severity of misbehaviors while providing a basis to take appropriate action to reduce dangerous activity. We developed a UAS prototype to showcase the practicality and effectiveness of the proposed system. It was demonstrated that dangerous driving activity on highways can be effectively and timely detected and analyzed.
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Reliability is one of the most important quality characteristics of components, products, and large and complex systems—but it takes a significant amount of time and resources to bring reliability to fruition. Thoroughly classroom- and... more
Reliability is one of the most important quality characteristics of components, products, and large and complex systems—but it takes a significant amount of time and resources to bring reliability to fruition. Thoroughly classroom- and industry-tested, this book helps ensure that engineers see reliability success with every product they design, test, and manufacture. Divided into three parts, Reliability Engineering, Second Edition handily describes the theories and their practical uses while presenting readers with real-world examples and problems to solve. Part I focuses on system reliability estimation for time independent and failure dependent models, helping engineers create a reliable design. Part II aids the reader in assembling necessary components and configuring them to achieve desired reliability objectives, conducting reliability tests on components, and using field data from similar components. Part III follows what happens once a product is produced and sold, how the m...
Research Interests: Computer Science, Medicine, Humans, Movement, Male, and 5 moreArm, Posture, Adult, Time Factors, and Task Performance and Analysis
Na2O-CaO-B2O3-P2O5 glasses have been prepared by the melt-quenching method. B2O3 content was systematically increased from 5 to 30mol%, at the expense of P2O5, in the chemical composition of these glasses. Density, Vickers microhardness... more
Na2O-CaO-B2O3-P2O5 glasses have been prepared by the melt-quenching method. B2O3 content was systematically increased from 5 to 30mol%, at the expense of P2O5, in the chemical composition of these glasses. Density, Vickers microhardness and fracture toughness of the prepared glasses were measured. In vitro bioactivity of the glasses was assessed by soaking in the simulated body fluid (SBF) at 37±0.5°C for 3, 7, 14 and 30days. The glasses were tested in the form of glass grains as well as bulk slabs. The structure and composition of the solid reaction products were analyzed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS). The kinetics of degradation of the glass particles were monitored by measuring the weight loss of the particles and the ionic concentration of Ca, P and B in the SBF solution using inductive coupled plasma-atomic emission spectroscopy (ICP-AES). The obtained results revealed the formation of a bioactive hydroxyapatite (HA) layer, composed of nano-crystallites, on the surface of glass grains after the in vitro assays. The results have been used to understand the formation of HA as a function of glass composition and soaking time in the SBF. It can be pointed out that increasing B2O3 content in glass composition enhances the bioactivity of glasses. The nanometric particle size of the formed HA and in vitro bioactivity of the studied glasses make them possible candidates for tissue engineering application.
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Life cycle cost (LCC) is the total cost of a system or product over its entire life span. It includes the cost of design, production, operation, maintenance, warranty, and decommission or disposal. This cost is extremely critical as it is... more
Life cycle cost (LCC) is the total cost of a system or product over its entire life span. It includes the cost of design, production, operation, maintenance, warranty, and decommission or disposal. This cost is extremely critical as it is one of the most critical ...
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This paper develops a simulation approach to the solution of closed-loop conveyor systems for which analytical solutions are infeasible or too compli cated. In addition, the paper considers cases involving more than one type of input to... more
This paper develops a simulation approach to the solution of closed-loop conveyor systems for which analytical solutions are infeasible or too compli cated. In addition, the paper considers cases involving more than one type of input to the conveyor systems. The arrival distribution patterns of re circulated units are also studied. The systems' measures of performance are evaluated. GPSS III/360 is utilized as the simulation language.
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ABSTRACT The concepts of system reliability are applied to optimum replacement policies for a container spreader subsystem. Actual failure data of the spreader components are analyzed; and the probability distributions of these failures... more
ABSTRACT The concepts of system reliability are applied to optimum replacement policies for a container spreader subsystem. Actual failure data of the spreader components are analyzed; and the probability distributions of these failures are determined. Models for optimum replacement policies for the spreader components are presented.
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In general, bench marking is understood as the pro-cess in which companies target key improvement areas within their firms, identify and study best practices by others in the same areas, and implement new processes and systems to enhance... more
In general, bench marking is understood as the pro-cess in which companies target key improvement areas within their firms, identify and study best practices by others in the same areas, and implement new processes and systems to enhance their own productivity and qual-ity. Though no ...
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Abstract This paper presents a methodology for analyzing large scale engineering problems with uncertain parameters. The coefficients of the objective function, the coefficients of the decision variables and the right hand side of the... more
Abstract This paper presents a methodology for analyzing large scale engineering problems with uncertain parameters. The coefficients of the objective function, the coefficients of the decision variables and the right hand side of the constraints are functions of random variables. The optimization problem is solved using the traditional simplex method. The uncertain parameters in the equations are expanded in the Taylor series. It is shown that the resulting equations are actually a set of linear programming recursive equations. Upon solving these equations, the required probabilistic statements can be easily established. An engineering example is provided to demonstrate the use of this methodology.
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The 2-year overall survival rates for 3D CRT versus IMRT were 51% and 65%, respectively (P = .5). Four locoregional failures occurred each in the 3D CRT (15%) and the IMRT (13%) patients. Grade ≥2 acute gastrointestinal toxicity was found... more
The 2-year overall survival rates for 3D CRT versus IMRT were 51% and 65%, respectively (P = .5). Four locoregional failures occurred each in the 3D CRT (15%) and the IMRT (13%) patients. Grade ≥2 acute gastrointestinal toxicity was found to be similar between the 3D ...
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ABSTRACT Computer Integrated Manufacturing requires integration of production processes, information systems, and cost information. This Project surveyed available computer software for automated production planning and inventory control... more
ABSTRACT Computer Integrated Manufacturing requires integration of production processes, information systems, and cost information. This Project surveyed available computer software for automated production planning and inventory control as well as computer software and hardware for data logging and monitoring shop floor activities. A baseline of vendor software/hardware applicable to Combat Ration Advanced Manufacturing Technology Demonstration (CRAMTD) was established. Working with other CRAMTD project teams, the computer network for the Demonstration Plant was defined. Two levels of networking are required: a low level network including PLCs and computers that run process control software, and a high level network for computers communicating with the database and planning/management functions. The process control computers link the networks. Commercially available software was recommended for process control. A customized database using a commercial database management system was selected for planning and management functions. Implementation of the selected software/hardware is underway. Production planning, Inventory control, Process control, Data logging, Shop floor monitoring
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We develop a generalized Extended Linear Hazard Regression (ELHR) model with linear time-varying coefficients to estimate reliability under normal operating conditions using failure time data obtained from accelerated conditions. The... more
We develop a generalized Extended Linear Hazard Regression (ELHR) model with linear time-varying coefficients to estimate reliability under normal operating conditions using failure time data obtained from accelerated conditions. The model considers the effect of ...
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General purpose centralized whole Web indexes have become increasingly harder to set up and maintain with the scaling problem of Web size. In this article, we present a novel approach to information indexing and searching based on... more
General purpose centralized whole Web indexes have become increasingly harder to set up and maintain with the scaling problem of Web size. In this article, we present a novel approach to information indexing and searching based on partitioning the Web according ...
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ABSTRACT In this paper we present new algorithms for processing a set of orders in automated warehousing systems. The proposed algorithms will process the orders by grouping some of them according to criteria developed by the authors. The... more
ABSTRACT In this paper we present new algorithms for processing a set of orders in automated warehousing systems. The proposed algorithms will process the orders by grouping some of them according to criteria developed by the authors. The travelling salesman algorithm is then utilized to determine the optimal distance travelled within the warehouse for every group of orders. Comparisons of the performance of the proposed algorithms are presented
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At the port-of-entry containers are inspected through a specific sequence of sensor stations to detect the presence of nuclear materials, biological and chemical agents, and other illegal cargo. The inspection policy, which includes the... more
At the port-of-entry containers are inspected through a specific sequence of sensor stations to detect the presence of nuclear materials, biological and chemical agents, and other illegal cargo. The inspection policy, which includes the sequence in which sensors are applied and the threshold levels used at the inspection stations, affects the probability of misclassifying a container as well as the cost and time spent in inspection. In this paper we consider a system operating with a Boolean decision function combining station results and present a multi-objective optimization approach to determine the optimal sensor arrangement and threshold levels while considering cost and time. The total cost includes cost incurred by misclassification errors and the total expected cost of inspection, while the time represents the total expected time a container spends in the inspection system. An example which applies the approach in a theoretical inspection system is presented.
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In this paper, an economic cost model is proposed for processes integrating both automatic process control (APC) and statistical process control (SPC) for quality monitoring and control. Both the special cause and common cause variations... more
In this paper, an economic cost model is proposed for processes integrating both automatic process control (APC) and statistical process control (SPC) for quality monitoring and control. Both the special cause and common cause variations are reduced by applying integrated APC and SPC. Traditionally, the integrated processes using APC and SPC are evaluated by the average run length (ARL). However,
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Accelerated Life Testing (ALT) is used to obtain failure time data quickly under high stress levels in order to predict product life and performance under the design stress. Most of the previous work on designing ALT plans is focused on... more
Accelerated Life Testing (ALT) is used to obtain failure time data quickly under high stress levels in order to predict product life and performance under the design stress. Most of the previous work on designing ALT plans is focused on the application of a single stress. ...
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Поиск в библиотеке, Расширенный поиск. ...
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ABSTRACT Similar to the univariate CUSUM chart, a multivariate CUSUM (MCUSUM) chart can be designed to detect a particular size of the mean shift optimally based on the scheme of a sequential likelihood ratio test for the noncentrality... more
ABSTRACT Similar to the univariate CUSUM chart, a multivariate CUSUM (MCUSUM) chart can be designed to detect a particular size of the mean shift optimally based on the scheme of a sequential likelihood ratio test for the noncentrality parameter. However, in multivariate case, the probability ratio of a sequential test is intractable mathematically and the test statistic based on the ratio does not have a closed form expression which makes it impractical for real application. We drive an approximate log-likelihood ratio and propose a multivariate statistical process control chart based on a sequential χ 2 test to detect a change in the noncentrality parameter. The statistical properties of the proposed test statistic are explored. The average runs length (ARL) performance of the proposed charts is compared with other MCUSUM charts for process mean monitoring. The experimental results reveal that the proposed charts achieve superior, both zero-state and steady-state, ARL performance over a wide range of mean shifts, especially when the dimension of measurements is large.
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ABSTRACT Accelerated life testing (ALT) is a widely used approach for reliability demonstration and prediction. Extensive research on ALT models has been focused on Accelerated Failure Time (AFT) models, Proportional Hazards (PH) models... more
ABSTRACT Accelerated life testing (ALT) is a widely used approach for reliability demonstration and prediction. Extensive research on ALT models has been focused on Accelerated Failure Time (AFT) models, Proportional Hazards (PH) models and some extensions of these two models. Mean residual life function provides a more descriptive measure of the aging process than the hazard function; however, it has not been used in modelling ALT. In this paper, we propose an ALT model based on a Proportional Mean Residual Life (PMRL) model and demonstrate its applicability in the reliability field. The model utilizes accelerated conditions data to estimate the reliability measures under normal operating conditions and provides a viable alternative to the accelerated failure time (AFT) model and the proportional hazards (PH) model. Some results concerning aging properties for the PMRL model are also studied.
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To realize the advantages of Computer Integrated Manufacturing (CIM), faster and more effective inspection and control systems are required than can be provided manually.