Elsayed Elsayed

• Rutgers, The State University of New Jersey

In a general high-dimensional process, a large number of process parameters or quality characteristics is found to be featured through their dependencies and relevance. The features that have similar characteristics or behaviors in the process operation can be categorized into multiple groups. Thus, when a few quality characteristics in the process...

Anomaly detection of three-dimensional (3D) topographic data is a challenging problem in spatial data analysis. In this paper, we investigate spatial patterns of 3D surface data that exhibit multiple in-control modes. In complex manufacturing processes, surfaces of final products could contain different topographic features from one in-control surf...

Critical systems, such as telecommunication networks, power grids, transportation networks, and supply chains, have been dramatically expanded over the past decades. To avoid significant interruptions of their services, failure-prevention technologies and strategies have been explored extensively. However, in addition to inherent faults and expecte...

The recent development of optical measuring instruments has increased the use of surface topographic data for monitoring the quality of the engineered surface. Due to the complexities of modern industrial processes, however, surfaces of final products under the normal manufacturing process may have multiple modes, such that the surface consists of...

Digital transformation driven by artificial intelligence (AI) allows Industry 4.0 and the internet of things (IIoT) to make significant advancements in automating, controlling, and improving the quality of numerous manufacturing processes. Three-dimensional (3D) surface topography of manufactured products holds important information about the quali...

The past several decades have witnessed an increasing number of natural and manmade hazards with a dramatic impact on the normal operations of the society. The occurrences of these hazards manifest a growing trend of uncertainty. Assessing the performance of systems under such hazards is a salient concern of researchers and practitioners. The notio...

Monitoring topographic variations in the engineered surface is crucial for quality engineers since the change in the surface finish is closely related to the performance of products. However, several challenging issues such as the existence of spatial autocorrelation within the surface, and changes of topographic features such as position and shape...

Three-dimensional (3D) optical systems have been recently deployed for the assessment of 3D topography of finished products during manufacturing processes. Although the 3D topographic data contain rich information about the product and manufacturing processes, existing monitoring approaches are incapable of capturing the complex characteristics bet...

Surface topography is a critical quality characteristic of many products and manufacturing processes. Various defects commonly appear on the topography of finished products in spatial patterns after or during manufacturing. These defects are difficult to be identified using traditional monitoring approaches because of the complex structure of topog...

One-shot units are produced in batches and stored in dormant or standby environment until retrieved or activated to perform their functions when needed. In this paper, we propose hybrid reliability testing approaches to utilize the advantages of non-destructive test (NDT) and destructive test (DT) for one-shot units’ reliability metrics assessment....

Corrosion is a major threat to the structural integrity and safe operation of infrastructures throughout the world. Corrosion growth modeling is important in structure maintenance planning. Existing models focus on the maximum corrosion pit depth growth which may lead to inaccurate life predictions since the corrosion volume growth may result in fa...

Technological advances have resulted in the introduction of new products and manufacturing processes that have a large number of characteristics and variables to be monitored to ensure the product quality. Simultaneous monitoring of variables under such a high-dimensional environment is quite challenging. Traditional approaches are less sensitive t...

Degradation branching is a common phenomenon in many real-life applications. The degradation of a location not only increases with time, but also propagates to other locations in the same system. While the degradation of an individual location has been studied extensively, research on degradation branching is sparse. In this paper, we develop a gen...

Traditional anomaly detection procedures assume that normal observations are obtained from a single distribution. However, due to the complexities of modern industrial processes, the observations may belong to multiple operating modes with different distributions. In such cases, traditional anomaly detection procedures may trigger false alarms whil...

Numerous color images are digitally reproduced today, mainly using the cyan, magenta, yellow and black ink set. The information in a printed image, however, may be distorted or lost due to the image's gradual color degradation as the result of ink fading and diffusion on the substrate. The degradation behavior of the inks can be difficult to predic...

The 3D surface topography of finished products is a key characteristic for monitoring the quality of products and manufacturing processes. The topography has unique properties in which the topographic values are spatially autocorrelated with their neighbours and the locations of topographic values randomly change from one surface to another under t...

This paper presents reliability modeling and estimation of multi-level balanced Unmanned Aerial Vehicles (UAV). This type of UAVs includes n pairs and m levels of rotors and is modeled as a (k1,k2)-out − of−(n, m) Pairs: G balanced system. In many cases, reallocating thrust force or changing rotors’ rotational directions when a failure occurs are i...

One‐shot units such as auto airbags and fire extinguishers are widely used in our daily lives. They perform their desired function only once and typically experience long‐term storage or standby status before use. Another example of one‐shot units is missiles, which could be stored for decades until there is a military need. When one‐shot units are...

In high-dimensional processes, monitoring process variability is considerably difficult due to the large number of variables and the limited number of samples. Monitoring changes in the covariance matrix of a multivariate process is often used for monitoring process variability under the assumption that only a few elements in the covariance matrix...

In most manufacturing processes, identifying the faulty process variables that may lead to process changes is crucial for quality engineers and practitioners. There are several parametric procedures for identifying faulty variables with the assumption that they follow multivariate normal distributions. However, in practice, the normality assumption...

One-shot units are produced in batches and stored until use. While in storage, they are subjected to random non-destructive tests (NDTs) throughout their life horizon to determine their reliability metrics. Some of the one-shot units (with nonhomogeneous characteristics) are retrieved from storage and launched for operational use when needed. Refer...

The applications of k-out-of-n pairs:G Balanced systems such as Unmanned Aerial Vehicle (UAV) have been widely used in industries. The reliability estimation for such systems is difficult to obtain due to the complexity of the problem: the operation of the systems depends on not only the number of operating pairs but also their spatial configuratio...

A great number of images are produced by color printers. Many factors lead to the degradation of printed images and its accurate prediction modeling is of a great interest. Previous research that addresses image degradation usually measures ink density or color of the prints. In this paper, we predict image degradation by the area coverage of inks....

This paper describes the design and analysis of an energy-absorption-system container made of chevron-pattern folded paper for the purpose of encasing supplies to be dropped from moving aircraft without using a parachute. A mathematical model of the energy absorption system is developed. The constitutive properties of the system are ascertained exp...

Reliability optimization is an important and challenging topic both in engineering and industrial situations as its objective is to design a highly reliable system that operates more safely and efficiently under constraints. Redundancy allocation problem (RAP), as one of the most well-known problems in reliability optimization, has been the subject...

In this paper, we investigate a system composed of mixtures of one-shot units with nonhomogeneous and time-dependent characteristics. We propose analytical expressions to predict system reliability metrics and consider a physics-statistics-based lifetime model to demonstrate the units’ failure mechanism as well as its failure process uncertainty. W...

Multiple sensors are commonly used for degradation monitoring. Since different sensors may be sensitive at different stages of the degradation process and each sensor data contain only partial information of the degraded unit, data fusion approaches that integrate degradation data from multiple sensors can effectively improve degradation modeling a...

Multistage statistical process control (SPC) is an effective procedure for ensuring quality of products in multistage manufacturing processes. Effective SPC approaches for monitoring and controlling quality in multistage processes are limited. Beta distributed data explained by process input variables are generally prevalent in multistage process i...

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 sensor...

Modeling components’ thermal fatigue life due to cyclic temperature fluctuation based on Coffin-Mason principle has been extensively investigated. However, sparse research assesses the thermal fatigue life by providing the reliability metrics of components/systems under thermal fatigue. The Birnbaum-Saunders (BS) distribution is developed to model...

In multistage manufacturing processes, autocorrelations within stages over time are prevalent and the classical control charts are often ineffective in monitoring such processes. In this paper, we derive a linear state space model of an autocorrelated multistage process as a vector autoregressive process, and construct novel multivariate control ch...

For smart electricity meter with multiple performance characteristics (PCs) with coupling relationships because of amounts of components experiencing multiple deteriorating processes, we develop a multivariate degradation modeling method via vine copulas to estimate the reliability of products with multiple PCs reflecting degradation states. In the...

High-dimensional applications pose a significant challenge to the capability of conventional statistical process control techniques in detecting abnormal changes in process parameters. These techniques fail to recognize out-of-control signals and locate the root causes of faults especially when small shifts occur in high-dimensional variables under...

The Multivariate Exponentially Weighted Moving Average (MEWMA) control chart is effective in detecting a small process mean shift. Its simplicity and generality stemfromthe assumption that the smoothing parameters of the variables are given constants and equally distributed on the diagonal of the smoothing matrix. Recently, the MEWMA model with the...

The applications of k-out-of- n pairs:G Balanced systems with spatially distributed units are emerging in aerospace and military industries. A k -out-of- n pairs:G Balanced system has n pairs of units distributed evenly in a circular configuration. The system operates when at least k pairs of units operate in a balanced arrangement. The reliability...

Many systems are composed of spatially distributed units which are subject to different operating conditions. The reliability of such systems depends not only on the reliability of individual units but also on their configurations. In this paper, we develop a degradation model for systems where units are spatially distributed and balanced. More spe...

In many cases, systems are required to provide a specified capacity such as the case of power distribution system. A system fails when its capacity does not meet the required minimum capacity. In this paper, we investigate reliability estimation of capacity-c-out-of-n pairs:G Balanced systems which consist of units in a balanced spatial configurati...

In a process with a large number of process variables (high-dimensional process), identifying which variables cause an out-of-control signal is a challenging issue for quality engineers. In this paper, we propose an adaptive step-down procedure using conditional T2 statistic for fault variable identification. While existing procedures focus on sele...

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...

Multistage statistical process control (SPC) is crucial to ensure the quality of the final product in multistage manufacturing processes. The output variables of a stage are input to the following stage and are considered to follow a parametric distribution. Beta distributed output variables explained by input variables are generally prevalent in r...

Distributed generation system integrating wind and solar energy emerged as a new paradigm for power supply. The goal of distributed generation planning is to determine the generation capacity, placement, and maintenance such that the system performance is optimized. In prior studies, the decision is often made assuming a deterministic operating con...

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...

Multistage statistical process control (SPC) is crucial to ensure the quality of the final product in multistage manufacturing processes. The output variables of a stage are input to the following stage and are considered to follow a parametric distribution. Beta distributed output variables explained by input variables are generally prevalent in r...

Each and every day, certain air route traffic control centers receive a large number of requested flight plans, each detailing the level, track, and entry time for the flight to enter the oceanic airspace. Because each airline independently optimizes its own flight plans, it is common that the requested flight plans result in an unbalanced usage of...

The reliability of k-out-of-n:G system has received attention due to its importance as a redundant configuration. The k-out-of-n pairs:G balanced system, which requires balancing the arrangement of units, is an emerging area for investigation due to its applicability in aerospace and military industries and unmanned aerial systems. In this paper, w...

The reliability of k-out-of-n:G system has received attention due to its importance as a redundant configuration. The k-out-of-n pairs:G balanced system, which requires balancing the arrangement of units, is an emerging area for investigation due to its applicability in aerospace and military industries and unmanned aerial systems. In this paper, w...

Failures of engineering structures and equipment are often attributed to the failure of a single component. Hence, it is important to identify critical components in a system and understand how a component's criticality changes over time under dynamic environments. This article investigates the criticality analysis for components with multiple comp...

In reliability analysis, the models used to aggregate the effect of time-varying stresses are generally invariant to the order of stress application, or stress sequence. A model is referred to as being insensitive to the stress sequence if the application of stress for units of time followed by stress for units of time is equivalent to applying str...

Traditional reliability analysis and predicting are performed by utilizing observed failure time or degradation data of test units or systems. However, in many cases, the reliability testing is performed during the entire life of the units by testing different samples with different characteristics at different times. This system is referred to as...

This article investigates the design of accelerated life testing plans under progressive censoring when test units experience competing failure modes and are subjected to either single or multiple stress types. The optimal test plan results in failure data at accelerated conditions that can then be used to obtain accurate reliability prediction at...

Accelerated life testing (ALT) using multiple stresses is commonly used in practice to resemble the operating stresses at normal operating conditions and obtain failure observations in a much shorter time. However, to date, there is little research into the theory of planning ALT for reliability estimation with multiple stresses. ALT with multiple...

Adaptive cumulative sum (ACUSUM) charts, which adjust the reference value dynamically based on estimated shift size, provide good performance in detecting a range of mean shifts. However, when the range is wide, ACUSUM may not perform well for small shifts over the range. An adaptive runs rule, which is motivated by the concept of supplementary run...

Reliability prediction of new components, products, and systems is a difficult task due to the lack of well-designed test plans that yield “useful” information during the test and due to the stochastic nature of the normal operating conditions. The accuracy of the reliability prediction has a major effect on the warranty cost and repair and mainten...

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 c...

It is universally accepted that physics-based models provide more accurate estimates of reliability than statistics-based model especially when the physics of failure of the units are well-understood. However, the underlying assumptions of such models regarding the deterministic nature of its parameters limit their applications, implementations and...

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 indi...

Background: Many failures of engineering structures and equipment are attributed to the failure of a single component. It is of great importance to identify those critical components and understand how components' criticality changes over time under dynamic environments. Objective: In this paper, we investigate the criticality analysis for componen...

This paper presents an overview of reliability testing, reliability estimation, and prediction models. It also presents approaches for the design of test plans which result in providing failure data and/or degradation data in a limited test duration. Equivalence of different test plans which result in similar reliability estimates is also discussed...

This paper develops an optimum Condition-Based Maintenance policy for continuously monitored degrading systems with multiple failure modes. The degradation of system state is described by a stochastic process, and a maintenance alarm is used to signal when the degradation reaches a threshold level. Unlike existing CBM models, we consider multiple s...

This paper presents a general framework for planning and optimizing Condition-Based Maintenance scheduling. We assume that the hazard function depends, not only on time, but also on the system state which degrades over time. The optimum threshold value triggering the maintenance is obtained by maximizing the system's availability over its life cycl...

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, tes...

Accelerated Life Testing (ALT) is an efficient approach to obtain failure observations by subjecting the test units to stresses severer than design stresses and utilize the test data to predict reliability at normal operating conditions. ALT is usually conducted under constant-stresses which need a long time at low stress levels to yield sufficient...

Accelerated life testing (ALT) is used to obtain failure time data in short duration under high stress levels in order to predict product life and performance under design conditions. The proportional hazards (PH) model, a widely used reliability prediction model, assumes constant ratio between the failure rate at high stress levels and the failure...

Many photovoltaic (PV) systems are nowadays installed all around the world. However, the reliability and the availability estimation of photovoltaic systems have not been received great attention from researchers. Reliability and availability are important consideration in the life-cycle of such systems. This paper presents a methodology for estima...

The objective of this project is to design and implement a fully automated innovative manufacturing process, based on patents co-authored by the principal investigator, for the development and production of flexible cushioning systems which have been tested in order for loads of supplies to be free-dropped from an aircraft at low altitude with airc...

Containers arriving at a port-of-entry are inspected using sensors and devices to detect drugs, weapons, nuclear materials and other illegal cargo. Measurement errors associated with the inspection process may result in higher misclassification of containers. In this paper, we propose and formulate three inspection policies for containers at port-o...

In probabilistic reliability analysis, it is common that the models relating time to failure with environmental stresses are insensitive to the sequence of the stress level application. For a step-stress model, this means that the probability of failure is a function of the exposure time at each stress and it is unaffected by the order of stress ap...

A system reliability model is developed and demonstrated when the individual components within the system are each subject to individual degradation processes, and for a series system, the system fails when any of the individual failure processes reaches a component-specific failure threshold. For this system model, the component degradation paths...

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 ev...

Statistical Process Control (SPC) chart is a graphical tool that helps to identify a possible process shift. Though the SPC chart is, in theory, a monitoring tool that reveals only the result of a statistical hypothesis testing, in practice the chart's signaling is often used for making process adjustment. In this paper we develop a robust estimato...

Accelerated life testing (ALT) is widely used to determine the failure time distribution of a product and the associated life-stress relationship in order to predict the product's reliability under normal operating conditions. Many types of stress loadings such as constant-stress, step-stress and cyclic-stress can be utilized when conducting ALT. E...

Accelerated life testing (ALT) is widely used to determine the failure time distribution of a product and the associated life-stress relationship in order to predict the product’s reliability under normal operating conditions. Many types of stress loadings such as constant-stress, step-stress and cyclic-stress can be utilized when conducting ALT. E...

EA Elsayed & Basily B Basily “Technology for Continuous Folding of Sheet Material into a honeycomb-like configuration” U.S. Patent No: 7,758,487 B2 . Date of issue: July 20, 2010

In the present study the chevron pattern of fold structure produced using a recently developed continuous folding technique is considered for the first time in the application of solar air collectors. An experimental study of two types of flat bed solar air collectors, with flat plate and chevron pattern absorbers, is carried out to investigate the...

At the port-of-entry, containers are inspected through a specific sequence of sensor stations to detect the presence of radioactive 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...

This paper considers a competing risk (degradation and sudden failure) maintenance situation. A maintenance model and a repair cost model are presented. The degradation state of the units is continuously monitored. When either the degradation level reaches a predetermined threshold or a sudden failure occurs before the unit reaches the degradation...

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...

This paper considers the problem of container inspection at a port-of-entry. Containers are inspected through a specific sequence to detect the presence of nuclear materials, biological and chemical agents, and other illegal shipments. The threshold levels of sensors at inspection stations of the port-of-entry affect the probabilities of incorrectl...

Accelerated life testing (ALT) is a method for obtaining failure time data of test units quickly under more severe conditions than the normal operating conditions. Typical ALT plans require the determination of stress types, stress levels, allocation of test units to those stress levels, duration of the test and other test parameters. Traditionally...

This paper presents a methodology for the failure probability evaluation of a thrust fluid bearing which plays a significant role in stability of machines rotors, mechatronic systems and high precision metrology systems. The static and dynamic behaviour of a fluid bearing depends on several parameters such as external load, the dimensions of the be...

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. However, as components or products become more reliable due to technological...

Containers and cargos arriving at port-of-entry are inspected using sensors and devices to detect drugs, weapons, nuclear materials and other illegal items. Measurement errors associated with the inspection process may result in higher percentage of misclassification of containers. In this paper, we propose and formulate three inspection policies f...

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. However, as components or products become more reliable due to technological...

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 time and cost savings compared to the situation when the system is repaired...

Abstract We summarize the findings of a recent bench marking study carried out in the pharmaceutical industry to assess and compare the manufacturing productivity of U. S., Japanese, and European manufacturers.

The problem of container inspection at ports-of-entry is formulated in several different ways as an optimization problem. Data generated from different analytical methods, x-ray detectors, gamma-ray detectors and other sensors used for the detection of chemical, biological, radiological, nuclear, explosive, and other illicit agents are often relied...

Accelerated life testing (ALT) is used to obtain failure data of products in a short time period in order to extrapolate the reliability and lifetime of the products under normal conditions. Estimation of the reliability and lifetime is based on models, which can be classified as parametric and non-parametric models. Non-parametric models are commo...