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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.
241

Geomagnetic Compensation for Low-Cost Crash Avoidance Project

Torres, John C 01 April 2011 (has links)
The goal of this work was to compensate for the effects of the Earth’s magnetic field in a vector field magnetic sensor. The magnetic sensor is a part of a low-cost crash avoidance system by Stephane Roussel where the magnetic sensor was used to detect cars passing when it was mounted to a test vehicle. However, the magnetic sensor’s output voltage varied when it changed orientation with respect to the Earth’s magnetic field. This limited the previous work to only analyze detection rates when the test vehicle travelled a single heading. Since one of the goals of this system is to be low-cost, the proposed solution for geomagnetic compensation will only use a single magnetic sensor and a consumer-grade GPS. Other solutions exist for geomagnetic compensation but use extra sensors and can become costly. In order to progress the development of this project into a commercial project, three separate geomagnetic compensation algorithms and a calibration procedure were developed. The calibration procedure compensated for the local magnetic field when the magnetic sensor was mounted to the test vehicle and allowed for consistent magnetic sensor voltage output regardless of the type of test vehicle. The first algorithm, Compensation Scheme 1 (CS1), characterized the local geomagnetic field with a mathematical function from field calibration data. The GPS heading was used as the input and the output is the voltage level of the Earth’s magnetic field. The second algorithm, Compensation Scheme 1.5, used a mathematical model of the Earth’s magnetic field using the International Geomagnetic Reference Field. An algorithm was developed to take GPS coordinates as an input and output the voltage contributed by the mathematical representation of the Earth’s magnetic field. The output voltages from CS1 and CS1.5 were subtracted from the calibrated magnetic sensor data. The third algorithm, Compensation Scheme 2 (CS2), used a high pass filter to compensate for changes of orientation of the magnetic sensor. All three algorithms were successful in compensating for the geomagnetic field and vehicle detection in multiple car headings was possible. Since the goal of the magnetic sensor is to detect vehicles, vehicle detection rates were used to evaluate the effectiveness of the algorithms. The individual algorithms had limitations when used to detect passing cars. Through testing, it was found that CS1 and CS1.5 algorithms were suitable to detect vehicles while stopped in traffic while the CS2 algorithm was suitable vehicle detection while the test vehicle is moving. In order to compensate for the limitations of the individual algorithms, a fused algorithm was developed that used a combination of CS1 and CS2 or CS1.5 and CS2. The vehicle speed was used in order to determine which algorithm to use in order to detect cars. Although the goal of this project is not vehicle detection, the rate of successful vehicle detection was used in order to evaluate the algorithms. The evaluation of the fused algorithm demonstrated the value of using CS1 and CS1.5 to detect vehicles when stopped in traffic, which CS2 algorithm cannot do. For a study conducted in traffic, using the fused algorithm increased vehicle detection rates by 51%-62% from using the CS2 algorithm alone. Since this work successfully compensated for geomagnetic effects of the magnetic sensor, the low-cost crash avoidance system can be further developed since it is no longer limited to driving in a single direction. Other projects that experience unwanted geomagnetic effects in their projects can also implement the knowledge and solutions used in this work.
242

Implementation of a Low Cost Reconfigurable Transform Architecture for Multiple Video Codecs

2012 June 1900 (has links)
Currently different types of transform techniques are used by different video codecs to achieve data compression during video frame transmission. Among them, Discrete Cosine Transform (DCT) is supported by most of modern video standards. The integer DCT (Int-DCT) is an integer approximation of DCT. It can be implemented exclusively with integer arithmetic. Int-DCT proves to be highly advantageous in cost and speed for hardware implementations. In particular, the 4x4 and 8x8 block size Int-DCTs have the increased applicability at the current multimedia industry because of their simpler implementation and better de-correlation performance for high definition (HD) video signals. In this thesis, we present a fast and cost-shared reconfigurable architecture to compute variable block size Int-DCT for four modern video codecs – AVS, H.264/AVC, VC-1 and HEVC (under development). Based on the symmetric structure of the transform matrices and the similarity in matrix operations, we have developed a generalized “decompose and share” algorithm to compute the 4x4 and 8x8 block size Int-DCT. The algorithm is later applied to those four video codecs. Our shared hardware approach ensures the maximum circuit reuse during the computation. The entire architecture is multiplier free and designed with only adders and shifters to minimize hardware cost and improve working frequency. Finally, the design is implemented on a FPGA and later synthesized in CMOS 0.18um technology to compare the cost and performance with existing designs. The results show significant reduction in hardware cost and meet the requirements of real time video coding applications.
243

Efficient Production Testing of High-Performance RF Modules and Systems using Low-Cost ATE

Srinivasan, Ganesh Parasuram 27 November 2006 (has links)
The proliferation of wireless communication devices in the recent past has increased the pressure on semiconductor manufacturers to produce quality radio frequency (RF) modules and systems at a low cost. This entails reducing their test cost as well, since the cost of testing modern RF devices can be up to 40% of their manufacturing cost. The high test cost of these devices can be mainly attributed to (a) the expensive nature of the RF automated test equipment (ATE) used to perform wafer-level and fully packaged RF functionality tests, (b) limited test point access for the application and capture of test signals, (c) the long test development and application times, and (d) the lack of diagnostic tools to evaluate and improve the performance of loadboards and test resources in high-volume tests. In this thesis, a framework for the efficient production testing of high-performance RF modules and systems using low-cost ATE is presented. This framework uses low-speed, low-resolution test resources to generate reliable tests for complex RF systems. Also, the test resources will be evaluated and improved ahead of high-volume tests to improve test yield and throughput. The components of the proposed framework are: (1) Genetic ATPG for reliable test stimulus generation using low-resolution test resources: A genetic algorithm (GA) based automatic test pattern generator (ATPG) to optimize the alternate test stimulus for reliable testing of complex RF systems using low-resolution, low-cost test resources. These test resources may be on-chip or off-chip. (2) Concurrent voltage/current alternate test methodology: A testing framework for efficiently testing the high-frequency specifications of RF systems using low-frequency spectral and/or transient current signatures. Suitable on-chip and/or off-chip design-for-test (DfT) resources are used to enable the source and capture operations at lower frequencies. (3) Loadboard checker: A checker tool to accurately characterize/diagnose the DfT resources on the RF loadboards used to enable test of RF devices/systems using low-cost ATE. (4) Advanced test signal processing algorithms: The performance of the low-cost ATE resources, in terms of their linearity/resolution, will be evaluated and improved to enable the accurate capture of the test response signals.
244

Research of the relationship between management control systems with different strategies and business performance- An example of Taiwan Synthetic Resin Industry

Wang, Yi-Ling 02 September 2011 (has links)
This research aims to discuss the influences of strategy choices on the management control systems. There is no absolute definition, range and classification of management control system which mainly includes management accounting and other controls. Moreover, management strategy is produced by the business after a series of evaluation and analysis of the internal and external environment. It is the business choice while proceeding resource operation and distribution and also the guidelines of business management activities. Management strategy makes the business achieve the goals, create competitive advantages and get more markets and chances in the intensely competitive environment. This research is explorative and uses business strategy as the variable and chooses the synthetic resin industry as the interview object. With Porter¡¦s general business strategy as the strategy classification standard, we differentiate the interviewed businesses into variation strategy and low-cost strategy and interview the outstanding persons separately. This research analyzes and induces the interview results as the following, 1. The group of cost-leading strategy emphasizes standards and is partial to centralization. In the application of management control system, they emphasize formal control and traditional cost control. However, the variation strategy emphasizes conformability and effective business strategy control. 2. The management control system of variation strategy company is partial to interactive control system and the management control system of low-cost strategy company prefers the diagnostic control system. 3. The degree of budget participation in variation strategy company is higher and it is lower in low-cost strategy company. 4. The degree of formalization in variation strategy company is higher and it is lower in low-cost strategy company. 5. The degree of participation and communication of interactive control system in variation strategy company is higher, and it is lower in low-cost strategy company. 6. Complete management control system helps the strategy performance.
245

A Low-cost Uncooled Infrared Detector Array And Its Camera Electronics

Akcoren, Dincay 01 February 2011 (has links) (PDF)
This thesis presents the development of integrated readout electronics for diode type microbolometers and development of external camera electronics for microbolometers. The developed readout electronics are fabricated with its integrated 160x120 resolution FPA (Focal Plane Array) in the XFAB SOI-CMOS 1.0 &mu / m process. The pixels in the FPA have 70 &mu / m pixel pitch, and they are sensitive in the 8&ndash / 12 &mu / m band of the infrared spectrum. Each pixel has 4 serially connected diodes, and diode turn on voltage changes as the temperature of the suspended and thermally isolated pixel increases due to the absorbed infrared power. Suspension of the pixels is obtained with a post-CMOS MEMS etching process, but this process requires no critical litography and/or deposition steps. This dramatically reduces the detector process cost, which makes this microbolometer FPA suitable for ultra low-cost applications such as automobile, security, and commercial applications. The readout electronics of the FPA include digital blocks such as timing and programming blocks as well as analog blocks such as a differential trans-conductance amplifier, a switched capacitor integrator, a sampleand- hold, and current DACs. This new readout design has reduced number of pins to simplify the external electronics and allows wafer-level vacuum packaging compared to the 128x128 FPA developed in a previous study at METU with the same approach. Both of these features further decrease the cost. Two kinds of external camera electronics are developed for two SOI type microbolometers. The first one is for the 128x128 SOI microbolometer previously designed in METU. The developed external camera electronics have 1.5mVrms noise, which is much less than the microbolometer noise. The overall system has an average NETD of 465 mK and a peak NETD of 320mK. The second developed external camera electronics are for the 160x120 SOI microbolometers that developed in the scope of this thesis. The developed external camera electronics has 0.55mVrms noise which is much less than the bolometer noise which is 5mVrms. The overall system has an average NETD of 820 mK and a peak NETD of 350 mK. Each of these external camera electronics include a custom designed PCB, an FPGA board with appropiate configurion and a software working on a PC. The custom designed PCB holds the external components for the microbolometer, an FPGA takes and processes the bolometer data and it sends to a PC, and a PC processes these data and forms a streaming video. These two external camera electronics allow to obtain human images verifying that the developed microbolometers can be used for security and automotive applications.
246

Remote plasma chemical vapor deposition for high efficiency heterojunction solar cells on low cost, ultra-thin, semiconductor-on-metal substrates

Onyegam, Emmanuel U. 01 September 2015 (has links)
In the crystalline Si solar cell industry, there is a push to reduce module cost through a combination of thinner substrates and increased cell efficiency. Achieving solar cells with sub-100 µm substrates cost-effectively is a formidable task because such thin substrates impose stringent handling requirements and thermal budget due to their flexibility, ease of breakage, and low yield. Moreover, as the substrate thickness decreases the surface passivation quality dictates the performance of the cells. Crystalline Si heterojunction (HJ) solar cells based on hydrogenated amorphous silicon (a-Si:H) have attracted significant interest in recent years due to their excellent surface passivation properties, potential for high efficiency, low thermal budget and low cost. HJ cells with ultra-passivated surfaces showing > 700 mV open-circuit voltages (Voc) and > 20% conversion efficiency have been demonstrated. In these cells, it has been identified that high-quality a-Si:H films deposited by a low-damage plasma process is key to achieving such high cell performance. However, the options for low-damage plasma deposition process are limited. The main objectives of this work are to develop a low-plasma damage a-Si:H thin film deposition process based on remote plasma chemical vapor deposition (RPCVD) and to demonstrate high efficiency HJ solar cells on bulk substrates as well as on ultra-thin silicon and germanium substrates obtained by a novel, low-cost semiconductor-on-metal (SOM) technology. This manuscript presents a detailed description of the RPCVD system and the process leading to the realization of high quality a-Si:H thin films and high efficiency HJ solar cells. First, p-type a-Si:H thin films are developed and optimized, then HJ solar cells are subsequently fabricated on bulk and ultra-thin Si and Ge SOM substrates without intrinsic a-Si:H passivation. Single HJ cells on ~ 500 µm bulk Si and ~25 µm ultra-thin substrates exhibited conversion efficiencies of η = 16% (Voc = 615 mV, Jsc = 34 mA/cm2, and FF = 77%) and η = 11.2% (Voc = 605 mV, Jsc = 29.6 mA/cm2, and FF = 62.8%), respectively. The performance of the ~25 µm cell was further improved to η = 13.4% (Voc = 645 mV, Jsc = 31.4 mA/cm2, and FF = 66.2%) by implementing the dual HJ architecture without front side i-layer passivation. For single HJ cells based on Ge substrates, the results were η = 1.78 % (Voc = 148 mV, Jsc = 35.1 mA/cm2, and FF = 1.78%) on ~500 µm bulk Ge, compared to η =5.3% (Voc = 203 mV, Jsc = 44.7 mA/cm2, and FF = 5.28%) on ~ 50 µm Ge SOM substrates. Respectively, the results obtained on ultra-thin SOM substrates are among the highest reported in literature for based on comparable architecture and substrate thickness. In order to achieve improved cell performance, dual HJ cells with i-layer passivation of both surfaces were fabricated. First, optimized RPCVD-based i-layer films were developed by varying the deposition temperature and H2 dilution ratio (R). It was found that excellent surface passivation on planar substrates with as-deposited minority carrier lifetimes > 1 ms is achievable by using deposition temperature of 200 ºC and moderate dilution ratio 0.5 ≤ R ≤ 1, even without the more rigorous RCA pre-cleaning process typically used in literature for achieving comparable results. Subsequently, dual HJ solar cells with i-layer films were demonstrated on planar and textured bulk Si substrates showing improved conversion efficiencies of η = 17.3% (Voc = 664 mV, Jsc = 34.34 mA/cm2 and FF = 76%) and η = 19.4% (Voc = 643 mV, Jsc = 38.99 mA/cm2, and FF = 77.5%), respectively. / text
247

Low cost low energy embedded processors for on-line biotechnology monitoring applications / Χαμηλού κόστους χαμηλής κατανάλωσης ενσωματωμένοι επεξεργαστές για βιοτεχνολογικές on-line monitoring εφαρμογές

Κρητικάκου, Αγγελική 03 August 2009 (has links)
On-line monitoring is an important challenge in future biotechnology applications, for instance in the domain of precision livestock farming, there is need for low-cost intelligent sensors to monitor animal welfare. The common way of observing a living organism is usually done by audio-visual ways performed by a human being, who is present on the scene. This method is, however, subjective, expensive, error prone and time consuming. Instead of performing an animal observation by a human being, automated objective surveillance, by means of low cost intelligent image sensors, can be used. With the use of cheap image sensors and with the help of image analysis techniques, an automated, objective, contact-less monitoring method of the behavior of the living organisms can be provided. Much knowledge has been obtained in the development and use of image analysis algorithms to automatically quantify body features of animals, their activity rate and their behavior. Such an automatic image analysis algorithm is combined with on-line modeling techniques in order to develop an application for the recognition of several behavioral phenotypes of laying hens. The procedure is divided in two phases, where an automatic computer vision algorithm detects the monitoring object from images captured by a video camera, and then another algorithm tracks the detected object through successive frames. Further work is required to integrate these algorithms into low-cost low-energy processing platforms, including embedded systems or even wearable devices. Only then, this important biotechnology development will lead to economically applicable solutions. The challenge of the present thesis especially includes the exploration of ultra-low energy implementation platforms of this biotechnology application. The initial application is developed in the MATLAB environment and is converted to C programming language. Dynamic range and precision analysis are performed to efficiently determine the required fixed-point word-lengths of the application’s variables. Finally, platform-independent and platform-dependent code transformations and integration of the algorithm to different ASIPs (Application Specific Instruction Processors) architectures are applied in order to achieve ultimate low energy consumption. / Η On-line παρακολούθηση αποτελεί μια σημαντική πρόκληση στις μελλοντικές βιοτεχνολογικές εφαρμογές, όπως παραδείγματος χάριν στον τομέα της κτηνοτροφίας, όπου είναι επιτακτική η ανάγκη χρήσης χαμηλού κόστους έξυπνων αισθητήρων στην παρακολούθηση της ευημερίας των ζωντανών οργανισμών. Ο συνήθης τρόπος παρακο-λούθησης ενός ζωντανού οργανισμού συνίσταται στη χρήση οπτικοακουστικών μέσων, τα οποία χειρίζεται ο ανθρώπινος παράγοντας που είναι παρόν. Η μέθοδος αυτή είναι κατά κύριο λόγο υποκειμενική, ακριβή, επιρρεπής σε σφάλματα και επιπροσθέτως χρονοβόρα. Αντ’ αυτού είναι δυνατό να εφαρμοσθεί μια αυτοματοποιημένη αντι-κειμενική επιτήρηση, η οποία λαμβάνει χώρα μέσω χαμηλού κόστους έξυπνων αισθητήρων εικόνας. Η χρήση των αισθητήρων, σε συνδυασμό με τη βοήθεια τεχνικών ανάλυσης εικόνας, παράγει μια αυτόματη αντικειμενική και εξ’ αποστάσεως μέθοδο πα-ρακολούθησης της συμπεριφοράς των ζωντανών οργανισμών. Τα τελευταία χρόνια η τεχνογνωσία στην ανάπτυξη και τη χρήση αλγορίθμων επεξεργασίας εικόνας, οι οποίοι εντοπίζουν αυτόματα τα χαρακτηριστικά των σωμάτων των ζωντανών οργανισμών, το ποσοστό δραστηριότητάς τους, καθώς και την συμπε-ριφορά τους, αναπτύσσεται ραγδαία. Ένας τέτοιος αλγόριθμος συνδυάζεται με on-line τεχνικές μοντελοποίησης αποσκοπώντας στην αναγνώριση διαφόρων φαινοτύπων συ-μπεριφοράς των ορνίθων. Η διαδικασία χωρίζεται σε δύο φάσεις, όπου κατά την πρώτη ένας αλγόριθμος με υπολογιστική όραση ανιχνεύει το αντικέιμενο παρακολούθησης από εικόνες που προέρχονται από μια κάμερα παρακολούθησης, και κατά τη δεύτερη ένας αλγόριθμος εντοπισμού αναλαμβάνει την παρακολούθηση του αντικειμένου σε δια-δοχικές εικόνες. Ακολούθως, είναι επιτακτική η υλοποίηση των αλγορίθμων σε χαμηλού κόστους χαμηλής κατανάλωσης πλατφόρμες επεξεργασίας, οι οποίες μπορούν να περιλαμβάνουν ενσωματωμένα ή ακόμα και ασύρματα συστήματα, ούτως ώστε η σημαντική αυτή βιοτεχνολογική ανάπτυξη να οδηγήσει σε οικονομικά εφικτές λύσεις. Η παρούσα μελέτη ανταπεξέρχεται στην πρόκληση της εξερεύνησης χαμηλής κατανάλωσης υλοποίησεων της βιοτεχνολογικής αυτής εφαρμογής. Η εφαρμογή έχει αναπτυχθεί σε υπολογιστικό περιβάλλον Matlab και εν συνεχεία ακολουθεί η μετάφρασή της σε C προγραμματιστική γλώσσα. Επιπρόσθετα, εφαρ-μόσθηκε δυναμική ανάλυση του εύρους και ανάλυση της ακρίβειας των μεταβλητών, με στόχο τον προσδιορισμό των μηκών των fixed point λέξεων. Εν κατακλείδι, πραγμα-τοποιήθηκαν platform-independent και platform-dependent μετασχηματισμοί της εφαρμογής και υλοποιείται σε διαφορετικές ASIP αρχιτεκτονικές αποσκοπώντας στην επίτευξη χαμηλής κατανάλωσης ενέργειας.
248

Multilevel Nanoengineering for Imprint Lithography

Konijn, Mark January 2005 (has links)
The current trend in pushing photo lithography to smaller and smaller resolutions is becoming increasingly difficult and expensive. Extreme ultra-violet lithography is an alternate method that has the potential to provide feature sizes down to 30 nm, however, it will come at an even greater cost. Nanoimprint lithography (NIL) is another lithographic technique which is promising to provide very high resolutions at a relatively low cost. Imprinting works by using a mold with a surface patterned with the required nano structures and pressing it into a substrate coated with a deformable polymer. Due to its direct pattern replication technique, it is very capable of reproducing three-dimensional structures, however limited research has been performed on this to date. In this study, investigations have been performed into developing a reliable process for creating SiN molds with sub-100 nm structures with variable height control. The process relies on a negative tone electron beam resist which can be patterned to various thicknesses by varying the exposure dosage. This allows for the creation of complex multi-layer structures in a single electron beam lithography step. These patterns then have been transferred into the SiN substrate by a single reactive ion etch. From here the mold is ready for use in imprinting. Study has also been performed into imprinting process as well. This includes the development of an imprint press, the manner in which NIL works. Investigations have been performed into the imprinting performance of 3D molds. Thermal expansion issues have been found and addressed, as have adhesion problems. Some other aspects of 3D NIL which have not been addressed in this study have been outlined in future work for further investigation.
249

Assessing women's participation in planning and construction of their houses : a case study of the Piesang River People's Housing Project, Durban.

Khumalo, Phumelele. 28 October 2014 (has links)
African women in the past were not given equal opportunities with men in planning and construction of their houses. As a result there is no clear indicative level of participation of women during the planning and construction of their houses. The People’s Housing Process is one of the approaches adopted by government and community organizations to encourage community participation in their housing projects but; women’s involvement is still not clear. Therefore this research is aiming to understand the activities performed by women, their roles in related activities, and the methods that they used to get involved in the planning and construction of their houses. A Qualitative research has been conducted to identify the level of women’s engagement in planning and construction of their houses in the People’s Housing Process (PHP) project at Piesang River. The findings of the study revealed that the Urban Poor Fund (UPF) savings system, together with the government subsidy for housing, empowered women to participate in planning and construction of their houses at Piesang River. Moreover; the findings indicated that town planning procedures and bylaws were not properly applied during project planning and implementation. In conclusion this dissertation recommends the formation of Municipal Community Partnership (MCP) for Piesang River FedUP community and EThekwini municipality, in which both stakeholders work together to address the way forward for the project in preference to continuing blaming each other for the shortfalls. / M.T.R.P. University of KwaZulu-Natal, Durban 2013.
250

A comparative analysis of the implications of Green Development versus conventional development imperatives : a case study of Lufhereng / Mari Strydom

Strydom, Mari January 2013 (has links)
This research study focuses on providing evidence that indicates that, making use of contemporary green building practices within a low cost subsidised housing project have more social, economical as well as environmental benefits than that of a conventional, non-green approach. Low cost subsidised housing units have become an everyday sight in the light of the global as well as the local economy. The increasing levels of unemployment and subsequent social problems lead to growing needs for this form of housing. As these projects consume a number of resources, steps need be taken to lighten the load – such as the carbon emissions - that is put on the environment. According to the United Nations, the key areas that are influenced by sustainability are environmental, economical as well as social. In South Africa, a number of government as well as local policies exist that regulates the planning and building practices of the low cost subsidised housing projects. These policies have been used as a foundation for this study. This study focuses on the Lufhereng project as a case study, and technology used in the Kuyasa as well as Cosmo City developments furthermore assisted in the groundwork for the comparison between the different construction approaches. The challenges facing the utilisation of a contemporary green building approach were researched, identified, discussed and recommendations were made. SAM (social accounting matrix) multiplier analysis on the Gauteng SAM obtained from the DBSA (Development Bank of South Africa), analysis and comparison of existing data as well as a qualitative questionnaire that was sent to industry stakeholders were utilised to obtain relevant information. The quantitative as well as qualitative data obtained from the primary as well as secondary research indicated that there are a number of aspects which has an influence on method of construction used in subsidised low cost housing units. The findings from literature as well as empirical research were analysed and discussed accordingly. Recommendations and suggestions regarding strategies that may be followed to increase the use of contemporary green approaches in these projects were made. These recommendations were based on the findings from literature as well as the research conducted for this study. The use of contemporary green approaches are vital for the social, economic as well as environmental sustainability of the country, and thus, ultimately of the world as a whole. It is, in this light, imperative that everything in our power should be done to preserve our resources by any means possible. / PhD (Urban and Regional Planning), North-West University, Potchefstroom Campus, 2013

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