Modeling Strategies to Improve the Dependability of Cloud Infrastructures

Cloud computing presents some challenges that need to be overcome, such as planning infrastructures that maintain availability when failure events and repair activities occur. Cloud infrastructure planning that addresses the dependability aspects is an essential activity because it ensures business continuity and client satisfaction. Redundancy mechanisms cold standby, warm standby and hot standby can be allocated to components of the cloud infrastructure to maintain the availability levels agreed in service level agreement (SLAs). Mathematical formalisms based on state space such as stochastic Petri nets and based on combinatorial as reliability block diagrams can be adopted to evaluate the dependability of cloud infrastructures considering the allocation of different redundancy mechanisms to its components. This chapter shows the adoption of the mathematical formalisms stochastic Petri nets and reliability block diagrams to dependability evaluation of cloud infrastructures with different redundancy mechanisms

Modeling, design and scheduling of computer integrated manufacturing and demanufacturing systems

This doctoral dissertation work aims to provide a discrete-event system-based methodology for design, implementation, and operation of flexible and agile manufacturing and demanufacturing systems. After a review of the current academic and industrial activities in these fields, a Virtual Production Lines (VPLs) design methodology is proposed to facilitate a Manufacturing Execution System integrated with a shop floor system. A case study on a back-end semiconductor line is performed to demonstrate that the proposed methodology is effective to increase system throughput and decrease tardiness. An adaptive algorithm is proposed to deal with the machine failure and maintenance. To minimize the environmental impacts caused by end-of-life or faulty products, this research addresses the fundamental design and implementation issues of an integrated flexible demanufacturing system (IFDS). In virtue of the success of the VPL design and differences between disassembly and assembly, a systematic approach is developed for disassembly line design. This thesis presents a novel disassembly planning and demanufacturing scheduling method for such a system. Case studies on the disassembly of personal computers are performed illustrating how the proposed approaches work

Hibrit artık robot kolu kullanarak yüksek performanslı taşlama işlemi geliştirmesi.

Automatic grinding using robot manipulators, requires simultaneous control of the robot endpoint and force interaction between the robot and the constraint surface. In robotic grinding, surface quality can be increased by accurate estimation of grinding forces where significant tool and workpiece deflection occurs. Tool deflection during robotic grinding operation causes geometrical errors in the workpiece cross-section. Also, it makes controlling the grinding cutting depth difficult. Moreover small diameter of the tool in robotic grinding causes different behavior in the grinding process in comparison with the tools that are used by universal grinding machines. In this study, a robotic surface grinding force model is developed in order to predict the normal and tangential grinding forces. A physical model is used based on chip formation energy and sliding energy. To improve the model for robotic grinding operations, a refining term is added. In order to include the stiffness of the tool and setup in the force model, penetration tests are implemented and their results are used in refining term of the force model. The model coefficients are estimated using a linear regression technique. The proposed model is validated by comparing model outputs with experimentally obtained data. Evaluation of the test results demonstrates the effectiveness of the proposed model in predicting surface grinding forces. In this thesis, a method is proposed for calculation of the tool deflection in normal and tangential directions based on grinding force feedback in these directions. Based on calculated values, a real-time tool deflection compensation algorithm is developed and implemented. Implementing surface grinding with constant normal force is a well-known approach for improving surface quality. Tool deflection in the robotic grinding causes orientation between the force sensor reference frame and tool reference frame. This means that the measured normal and tangential forces by the sensor are not actual normal and tangential interaction forces between the tool and workpiece. In order to eliminate this problem, a resultant grinding force control strategy is designed and implemented for a parallel hexapod-robotic light abrasive surface grinding operation. Due to the nonlinear nature of the grinding operation, a supervised fuzzy controller is designed where the reference input is identified by the proposed grinding force model. Evaluation of the experimental results demonstrates significant improvement in grinding operation accuracy using the proposed resultant force control strategy in parallel with a real-time tool deflection compensation algorithm. The final aim of this thesis is to develop a posture optimization strategy for robotic grinding operation using 12 DOF hybrid redundant manipulator. The 12 DOF redundant hybrid manipulator of present study is composed of a 6 DOF serial ABB IRB2000 robot and a 6 DOF PI H-824 hexapod where the parallel hexapod is connected to the end of the serial ABB manipulator. Here the fifth joint (wrist) of the ABB serial manipulator is the weakest joint in the robot, so the computed torque of this joint is selected as the cost function. The aim is to minimize this factor by finding the best configuration of the hybrid manipulator using genetic algorithm approach. For such a purpose, a complete kinematic and dynamic model of the 12 DOF manipulator is developed where the output of the grinding force model is fed into the dynamic model as external reaction forces. The computed torque of the wrist joint is given to the optimization module and new configuration is generated by the module and is given to the dynamic model. This process continues until converge to the minimum computed torque value. Then the optimal configuration is chosen for the grinding operation. The evaluation of this posture optimization approach shows its great ability to decrease the necessary actuating torques of the redundant manipulator joints.Ph.D. - Doctoral Progra

Pastoral Neolithic Settlement at Luxmanda, Tanzania

The later Holocene spread of pastoralism throughout eastern Africa profoundly changed socio-economic and natural landscapes. During the Pastoral Neolithic (ca. 5000–1200 B.P.), herders spread through southern Kenya and northern Tanzania—areas previously occupied only by hunter-gatherers—eventually developing the specialized forms of pastoralism that remain vital in this region today. Research on ancient pastoralism has been primarily restricted to rockshelters and special purpose sites. This paper presents results of surveys and excavations at Luxmanda, an open-air habitation site located farther south in Tanzania, and occupied many centuries earlier, than previously expected based upon prior models for the spread of herding. Technological and subsistence patterns demonstrate ties to northerly sites, suggesting that Luxmanda formed part of a network of early herders. The site is thus unlikely to stand alone, and further surveys are recommended to better understand the spread of herding into the region, and ultimately to southern Africa

Team Teaching: An Innovative Pedagogical Model to Radically Restructure the Classroom and Transform Social Work Education

This Banded Dissertation focuses on exploring the concept of team teaching within social work education by restructuring the traditional single teacher classroom structure. The Banded Dissertation comprises three scholarly products examining social work education. Pedagogical innovations introduced in this dissertation aim to address anti-racism, diversity, equity, and inclusion within social work education. The first product explored Master of Social Work (MSW) student perceptions of team teaching efficacy using a descriptive mixed-methods design. Data was collected through pre, and post-test surveys from MSW students (n= 76) enrolled in classes taught by teams of social work instructors. Findings described student perceptions of team teaching as an effective pedagogical model of instruction. Students identified teaching partnerships, knowledge and expertise, and diverse perspectives as factors that contribute to team teaching efficacy.The second product is a conceptual paper that integrates Critical Race Theory (CRT) framework to explore interracial team teaching as an emerging pedagogical model to teach anti-racism within social work education. An exploratory qualitative systematic review shows that CRT tenets identified by Sólorzano et al. (2005)align with anti-racist social work education delivered via an interracial team-taught model. The third scholarly product applies Scholarly Personal Narrative as the research methodology to examine the author’s experiences within academia as a man of color—both as a student and teacher. Findings suggest that ethnic and racial disproportionality in social work education requires academic institutions to hire more Black, Indigenous, and People of Color (BIPOC) faculty, establish mentorship programs, and expand educational and financial support to BIPOC students. The scholarly products presented in this Banded Dissertation contribute to the growth of knowledge on team teaching utility in social work education to enhance student learning. These products add to the discourse on the need for pedagogical innovation in social work education to address anti-racism, diversity, equity, and inclusion and prepare future generations of anti-racist social work practitioners and scholars

Constraint-Based Synthesis of Shape-Morphing Structures in Virtual Reality

This manuscript outlines a novel approach to the design of compliant shape-morphing structures using constraint-based design method. Development of robust methods for designing shape-morphing structures is the focus of multiple current research projects, since the ability to modify geometric shapes of the individual system components, such as aircraft wings and antenna reflectors, provides the means to affect the performance of the corresponding mechanical systems. Of particular interest is the utilization of compliant mechanisms to achieve the desired adaptive shape change characteristics. Compliant mechanisms, as opposed to the traditional rigid link mechanisms, achieve motion guidance via the compliance and deformation of the mechanism’s members. The goal is to design a single-piece flexible structure capable of morphing a given curve or profile into a target curve or profile while utilizing the minimum number of actuators. The two primary methods prevalent in the design community at this time are the pseudo-rigid body method (PRBM) and the topological synthesis. Unfortunately these methods either tend to suffer from a poor ability to generate potential solutions (being more suitable for the analysis of existing structures) or are susceptible to overly-complex solutions. By utilizing the constraint-based design method (CBDM) we aim to address those shortcomings. The concept of CBDM has generally been confined to the Precision Engineering community and is based on the fundamental premise that all motions of a rigid body are determined by the position and orientation of the constraints (constraint topology) which are placed upon the body. Any mechanism motion path may then be defined by the proper combination of constraints. In order to apply the CBDM concepts to the design and analysis of shape-morphing compliant structures we propose a tiered design method that relies on kinematics, finite element analysis, and optimization. By discretizing the flexible element that comprises the active shape surface at multiple points in both the initial and the target configurations and treating the resulting individual elements as rigid bodies that undergo a planar or general spatial displacement we are able to apply the traditional kinematics theory to rapidly generate sets of potential solutions. The final design is then established via an FEA-augmented optimization sequence. Coupled with a virtual reality interface and a force-feedback device this approach provides the ability to quickly specify and evaluate multiple design problems in order to arrive at the desired solution.</p

The Technological and Socio-Economic Organization of the Elmenteitan Early Herders in Southern Kenya (3000-1200 BP)

Understanding how the modern world has been shaped by the origins and spread of food production deeper in our past is an enduring and fundamental goal of anthropological archaeology. In Africa, mobile pastoralism emerged as a way of life that is economically and ideologically focused on herding livestock, and spread across the continent over the last 8000 years. Despite the potential importance of African pastoralism within global dialogues on the origins of food production, the social and economic systems that sustained its spread through the continent remain poorly understood. A culture-complex known as the Elmenteitan is associated with the spread of stone-tool using herders into southern Kenya, and the development of a long-distance obsidian exchange system stemming from a single quarry site on top of Mt. Eburru from 3000-1400 years ago. This dissertation uses the Elmenteitan case-study to mount the first comprehensive study of how economic needs, environmental conditions, and socio-cultural institutions shaped ancient pastoralist technological strategies. To accomplish this I directed archaeological surveys and excavations at the Elmenteitan Obsidian Quarry on Mt. Eburru to test hypotheses regarding the social systems involved in herder obsidian procurement. I engaged in intensive analysis of stone tool debris at the quarry in order to establish a start point for a larger comparative analysis of 12 lithic assemblages from Elmenteitan sites spread across southwestern Kenya. Based on archaeological and lithic datasets, I demonstrate that Elmenteitan herders deployed a regionally uniform lithic technology that emphasized flexibility in responding to environmental diversity and climatic change. I show that this form of technological organization was supported by a system of obsidian access and distribution that was maintained through investment in social institutions that bound Elmenteitan communities into a system of reciprocity, alliance, and cultural identity. I conclude that the integration of social, economic, and technological systems developed as strategy for ensuring long-term risk mitigation in unpredictable environments

Undergraduate and Graduate Course Descriptions, 2023 Spring

Wright State University undergraduate and graduate course descriptions from Spring 2023