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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

A need for systems architecture approach for next generation mine warfare capability

Hibbert, Kirk R. 09 1900 (has links)
When operating in a sea borne environment, sea mines can prevent U.S. Navy vessels from meeting operational objectives. Sea mines have the potential of damaging, or destroying ships at sea. The U.S. Navy conducts mine warfare (MIW) operations to meet this threat. Although effective against mining, our countermining operations are currently employing 1960â s technology in an attempt to keep pace with new Concepts of Operations (CONOPS). Todayâ s legacy MIW processes currently employed by the warfighter, although capable of countering the mining threat, are a reactive process that is slow to engage and employ assets that are cumbersome to operate. With the advent of new technologies, a transformation of MIW capability is on the horizon and has the potential of influencing how the U.S. Navy maintains maritime dominance in the openoceans and littoral environments. The influence that technologies bring to MIW includes multi-spectral sensors, laser imagery, compact modular systems, unmanned and semi-autonomous weapons, as well as new communications architecture and tactics. Although these technical innovations present a level of capability superior to the existing legacy systems, developmental barriers and the lack of an overarching systems architecture will hinder or prevent these systems from being effectively integrated into tomorrowâ s CONOPS.
52

Aerially deployed real-time targeting sensor net

Diamond, Scott M. 06 1900 (has links)
This thesis focuses on developing and analyzing a model for an aerially deployed real-time targeting sensor net to close the current gap that exists between the potential technological-doctrinal capability within society and that of the military. It outlines current real-time targeting need due to the decomposition of warfare after the fall of the Soviet Union, and portrays the targeting discrepancies in the Global War on Terror. From end-user surveys requirements are layed out for a system of systems to meet targeting needs. A feasible solution consisting of a system architecture anchored in existing commercial off the shelf technology is proposed to meet the discrete deliverables necessary to accomplish targeting goals to deal with asymmetric threats in opaque environments. / US Navy (USN) author.
53

Synchronisation of communication systems

Ramsay, Robert Duncan. January 1971 (has links) (PDF)
No description available.
54

Automotive Sensor Fusion for Situation Awareness

Lundquist, Christian January 2009 (has links)
<p>The use of radar and camera for situation awareness is gaining popularity in automotivesafety applications. In this thesis situation awareness consists of accurate estimates of theego vehicle’s motion, the position of the other vehicles and the road geometry. By fusinginformation from different types of sensors, such as radar, camera and inertial sensor, theaccuracy and robustness of those estimates can be increased.</p><p>Sensor fusion is the process of using information from several different sensors tocompute an estimate of the state of a dynamic system, that in some sense is better thanit would be if the sensors were used individually. Furthermore, the resulting estimate isin some cases only obtainable through the use of data from different types of sensors. Asystematic approach to handle sensor fusion problems is provided by model based stateestimation theory. The systems discussed in this thesis are primarily dynamic and they aremodeled using state space models. A measurement model is used to describe the relationbetween the state variables and the measurements from the different sensors. Within thestate estimation framework a process model is used to describe how the state variablespropagate in time. These two models are of major importance for the resulting stateestimate and are therefore given much attention in this thesis. One example of a processmodel is the single track vehicle model, which is used to model the ego vehicle’s motion.In this thesis it is shown how the estimate of the road geometry obtained directly from thecamera information can be improved by fusing it with the estimates of the other vehicles’positions on the road and the estimate of the radius of the ego vehicle’s currently drivenpath.</p><p>The positions of stationary objects, such as guardrails, lampposts and delineators aremeasured by the radar. These measurements can be used to estimate the border of theroad. Three conceptually different methods to represent and derive the road borders arepresented in this thesis. Occupancy grid mapping discretizes the map surrounding theego vehicle and the probability of occupancy is estimated for each grid cell. The secondmethod applies a constrained quadratic program in order to estimate the road borders,which are represented by two polynomials. The third method associates the radar measurementsto extended stationary objects and tracks them as extended targets.</p><p>The approaches presented in this thesis have all been evaluated on real data from bothfreeways and rural roads in Sweden.</p> / IVSS - SEFS
55

Visco-Elastic Creep in the Lumbar Spine Associated with Static Flexion: A Feline Model

Hatipkarasulu, Guntulu Selen 18 April 2002 (has links)
Musculoskeletal disorders (MSDs) have become a major health concern with the industrial revolution and technological advances. The National Institute for Occupational Safety and Health (NIOSH) recently estimated the cost of MSDs at $13 to $20 billion annually. Back, spine, and spinal cord disorders add up to 60% of the total MSD injuries. Based on pervious studies, it is known that lumbar ligaments play a limited or little role in stabilizing the spine; where as the musculature around the spine is the major stabilizing structure. However, repetitive or prolonged static displacement or load induces creep in passive tissues of the spine including ligaments, disc, and joint capsule. The resulting creep in the ligaments or the laxity developed in the viscoelastic structure causes instability of the spine associated with pain, leaving the spine without protection. This study concentrates on the response of the lumbar spine when subjected to static loading. Twenty-two in vivo feline preparations were subjected to four different intensities of load, and electrical activity of the multifidus muscles for six lumbar levels and creep behavior of the supraspinous ligament were observed for twenty minutes of loading and seven hours of rest period. Results show that seven hours of rest period was not enough for the multifidus activity and creep developed in the viscoelastic tissue to return to normal. Larger loads elicited larger initial vertical displacement in the lumbar spine as well as higher creep values. Based on the observed data, four exponential and time dependant models were developed in the mathematical description of the electrical activity and the vertical displacement in the supraspinous ligament for both loading and recovery periods.
56

DESIGNING FLEXIBLE ENGINEERING SYSTEMS UTILIZING EMBEDDED ARCHITECTURE OPTIONS

Pierce, Jeff G. 13 April 2010 (has links)
This dissertation develops and applies an integrated framework for embedding flexibility in an engineered system architecture. Systems are constantly faced with unpredictability in the operational environment, threats from competing systems, obsolescence of technology, and general uncertainty in future system demands. Current systems engineering and risk management practices have focused almost exclusively on mitigating or preventing the negative consequences of uncertainty. This research recognizes that high uncertainty also presents an opportunity to design systems that can flexibly respond to changing requirements and capture additional value throughout the design life. There does not exist however a formalized approach to designing appropriately flexible systems. <p>This research develops a three stage integrated flexibility framework based on the concept of architecture options embedded in the system design. Stage One defines an eight step systems engineering process to identify candidate architecture options. This process encapsulates the operational uncertainty though scenario development, traces new functional requirements to the affected design variables, and clusters the variables most sensitive to change. The resulting clusters can generate insight into the most promising regions in the architecture to embed flexibility in the form of architecture options. Stage Two develops a quantitative option valuation technique, grounded in real options theory, which is able to value embedded architecture options that exhibit variable expiration behavior. Stage Three proposes a portfolio optimization algorithm, for both discrete and continuous options, to select the optimal subset of architecture options, subject to budget and risk constraints. Finally, the feasibility, extensibility and limitations of the framework are assessed by its application to a reconnaissance satellite system development problem. Detailed technical data, performance models, and cost estimates were compiled for the Tactical Imaging Constellation Architecture Study and leveraged to complete a realistic proof-of-concept.
57

Supply Chain Models for an Assembly System with Preprocessing of Raw Materials

Rahman, Mohammad Anwar Ashek 07 February 2003 (has links)
An assembly line that procures raw materials from outside suppliers and processes the materials into finished products is considered in this research. An ordering policy is proposed for raw materials to meet the requirement of a production facility, which, in turn, must deliver finish products in a fixed quantity at a fixed time interval to the outside buyers. Two different types of raw materials, unfinished and ready-to-use, are procured for the manufacturing system. The unfinished raw materials are turned into processed raw materials after preprocessing. In the assembly line, the processed raw materials and the ready raw materials are assembled to convert into the final products. A cost model is developed to aggregate the total costs of raw materials, Work-in-process, and finished goods inventory. Based on the product design and manufacturing requirement a relationship is established between the raw materials and the finished products at different stages of production. A non-linear integer-programming model is developed to determine the optimal ordering policies for procurement of raw materials, and shipment of assembly product, which ultimately minimize the total costs of the model. Numerical examples are presented to demonstrate the solution technique. Sensitivity analysis is performed to show the effects of the parameters on the total cost model. Future research direction is suggested for further improvement of the existing results.
58

Optimal Batch Quantity Models for A Lean Production System with Rework and Scrap

Biswas, Pablo 10 January 2003 (has links)
In an imperfect manufacturing process, the defective items are produced with finished goods. Rework process is necessary to convert those defectives into finished goods. As the system is not perfect, some scrap is produced during this process of rework. In this research, inventory models for a single-stage production process are developed where defective items are produced and reworked, where scrap is produced, detected and discarded during the rework. Two policies of rework processes are considered (a) First policy: rework is done within the cycle, and (b) Second policy: rework is done after N cycles of normal production. Also, three types of scrap production and detection methods are considered for each policy, such as (i) scrap is detected before rework, (ii) scrap is detected during rework and (iii) scrap is detected after rework. Based on these inventory situations, the total cost functions for a single-stage imperfect manufacturing system are developed to find the optimum operational policy. Some numerical examples are provided to validate the model and a sensitivity analysis is carried out with respect to different parameters used to develop the model.
59

Hydrocone Crusher : A new fast robust design of the hydraulic system

Vestman, Johan, Sjöberg, Patrik January 2008 (has links)
<p>This master thesis has been conducted at Sandvik Svedala. The thesis is the first step towards a new construction of a hydraulic system for a Hydrocone crusher. First we studied how contaminations entered the system of today. Then the work began with designing several concepts to control the crusher. These basic concepts were presented to Sandvik and the one was chosen for further development was fine tuned and a system was built. This system was tested at a test rig to verify that the basic ideas were working. This test pointed out the disadvantages of the system, and the improvements needed to become a future industrial solution.</p>
60

Some observations toward decentralized control under saturation

Malek, Babak. January 2009 (has links) (PDF)
Thesis (M.S. in electrical engineering)--Washington State University, December 2009. / Title from PDF title page (viewed on Feb. 4, 2010). "School of Electrical Engineering and Computer Science." Includes bibliographical references (p. 52-53).

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