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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.

3-D Positioning in Large Warehouses using Radio-frequency identification

Karhu, Jonas January 2014 (has links)
In large warehouses, there are a lot of articles that needs do be kept track of. As the number of articles grows larger, the administrative complexity increases. Thus, a solution that automatically keeps track of the position of each article in real-time is of interest. That is, if an item in the warehouse is moved, no manual administration should be needed to know the new position of the item. Radio detection and ranging (RADAR) is a ranging technique that doesn’t need to communicate with an object to find the distance to it, instead signals are sent and when they are reflected off the object and returned to the sender, the distance to the object may be calculated. However, you cannot tell two equally shaped objects apart purely based on RADAR techniques. There are many other techniques for ranging, sound navigation and ranging (SONAR) is another example, but they all lack the possibility of detecting the identity of the object. So, in order to find a specific item’s position, some kind of  communication with the item is necessary. Radiofrequency identification (RFID) is a neat technology with which this is possible. An RFID reader can send radio signals out in the air, and objects that are in the vicinity of the reader and are tagged with an RFID tag can receive that signal and respond with it’s unique identification number. This way, the RFID reader can identify the RFID tagged object from a distance. There are also a variety of ways to approximate the distance between reader and tag. Unfortunately this is a rather difficult task, especially in indoor  environments. There are already some existing products on the market that uses RFID for different kinds of positioning. In this thesis, the theory behind positioning, the fundamentals of RFID and different positioning solutions will be analysed and presented. A number of tests were carried out with an RFID system within the ultra-high frequency (UHF) band, which is around 866 MHz. The test system only supported range estimation based on the received signal strength indicator (RSSI) and the test results showed that narrowband RSSI measurements are highly disturbed by multipath propagation which make the overall positioning performance insufficient. Further analysis of time based range estimation techniques, such as time of arrival (TOA), time of flight (TOF) and time difference of arrival (TDOA), revealed that better positioning accuracy is possible, especially if ultra-wide bandwidth (UWB) is used.

Securing GNSS Receivers with a Density-based Clustering Algorithm

Tuhin, RASHEDUL AMIN January 2015 (has links)
Global Navigation Satellite Systems (GNSS) is in widespread use around the world for numerous purposes. Even though it was first developed for military purposes, nowadays, the civilian use has surpassed it by far. It has evolved to its finest state in recent days and still being developed further towards pinpoint accuracy. With all the improvements, several vulnerabilities have been discovered by researchers and exploited by the attackers. Several countermeasures have been and still being implemented to secure the GNSS. Studies show that GNSS-based receivers are still vulnerable to a very fundamentally simple, yet effective, attack; known as the replay attack. The replay attack is particularly harmful since the attacker could make the receiver calculate an inaccurate position, without even breaking the encryption or without employing any sophisticated technique. The Multiple Combinations of Satellites and Systems (MCSS) test is a powerful test against replay attacks on GNSS. However, detecting and identifying multiple attacking signals and determining the correct position of the receiver simultaneously remain as a challenge. In this study, after the implementation of MCSS test, a mechanism to detect the attacker controlled signals has been demonstrated. Furthermore, applying a clustering algorithm on the product of MCSS test, a method of correctly determining the position, nullifying the adversarial effects has also been presented in this report.

Strategická pozice značky a její definování v konkurenčním prostředí / Strategic Position of a Trademark and its Definition in the Competitive Environment

Froňková, Tereza January 2008 (has links)
The thesis focuses on defining the strategic brand positioning, its long term building possibilities in a competitive market environment and assesment methods. The thesis includes case study on international cosmetic brand Dove and how the communication influences the brand.

Post WTO Competitive Strategy & Positioning in Steel Trade ¡V In the Case of China Steel Global Trading Corp.

Chen, Kuen-Mu 30 June 2002 (has links)
Since Taiwan and China have become the members of the World Trade Organization in the year of 2002, many companies are gaining various opportunities while meeting the challenges of unpredictable and fast-paced markets. China Steel Global Trading Corporation (CSGT), which is responsible for the international business of China Steel Corporation (CSC) Group, should take these opportunities to broaden the overseas market, especially in China. As the international trading brain and strong arm of the CSC Group as well as the export exclusive agent of China Steel Corporation and China Steel Aluminum Corporation, CSGT has built its international marketing network after 5 years¡¦ efforts. CSGT take the advantages of image, technique, marketing and finance of CSC Group and has been deeply trusted by the foreign customers and suppliers. Through the strength and resource advantages of CSC Group and steel industry, CSGT is going to diversify to other industry materials, consumer goods or others in the coming future. CSGT also has the vision to turn into a worldwide and whole-wise trading company by cooperating with other company in different fields. The thesis is about how to fully utilize the resource of CSC group to rebuild the competitive strategies while environmental challenge and structured chaos, to set up the sustainable competitive advantages and core competence, to reach the vision of CSGT. With the intersectional brain storming we reviewed the strength, weakness, opportunity, and threat of CSGT, found out the core competence, adopted the strategy alliance , rebuilt the value chain and new competitive positioning. Finally we come to the vision of Great Trading Firm ¡Xthe Eternal CSGT Builds the Last.

The Fabrication of Two Dimension Photonic Crystal and Positioning System

Hsu, Hung-hui 17 July 2008 (has links)
In this thesis, we use E-Beam lithography to finish the process of positioning system and 2D photonic crystal. We use the new E-Beam system to define some array patterns. By this test, we obtain the minimum linewidth is 55nm, and the maximum writable range is 250£gm*250£gm. First, we fabricated the 2D photonic crystal microcavity and positioning system on the InGaAs/InAlAs which grown by molecular beam epitaxy (MBE) on InP substrate at 1564nm emission wavelength by E-beam lithography. For the positioning system, we set up a origin point first. And then we design many rectangles whose length is 1£gm, width is 10£gm and gap is 1£gm along X axis and Y axis from the origin point. All of the patterns are regarded as the ruler. Finally, we design a big rectangle whose length is 250£gm and width is 10£gm to adjust the positioning angle above the ruler. The maximum error of the positioning system is 20nm. For the 2D photonic crystal (2D PhC) microcavity, a triangular array of air columns is adopted. The lattice constant and air columns radius are 1150nm and 460nm, respectively. The TE modes photonic band gap of this structure are corresponding to wavelength range in 1535nm~1635nm. We remove signal defect and seven defects in the 2D PhC to form 2D PhC microcavities and the PhC microcavities have many defect modes. The Micro-PL measurement shows when the etching depth was deep enough, the PhC microcavities which have 1-defect and 7-defect appeared defect mode at 1622nm (a/£f=0.74) both. The intensity of 7-defect PhC is 7 times than 1-defect PhC. Both of them cooperate with our simulation and design. And the maximum Q value is about 324 at the defect mode.

Ionospheric scintillation effects on global positioning system receivers

Knight, Mark Frederick. January 2000 (has links) (PDF)
Bibliography: p. 297-304. Uses a widely accepted stochastic model of scintillation activity to investigate the effects of scintillations on GPS receivers and systems.

Development and Testing of Augmentations of Continuously-Operating GPS Networks to Improve Their Spatial and Temporal Resolution

Ge, Linlin, School of Geomatic Engineering, UNSW January 2000 (has links)
Continuously-operating networks of GPS receivers (CGPS) are not capable of determining the characteristics of crustal deformation at the fine temporal or spatial scales required. Four ???temporal densification schemes??? and two 'spatial densification schemes' to augment the CGPS networks have been developed and tested. The four ???temporal densification schemes??? are based on the high rate Real-Time Kinematic (RTK) GPS technique, GPS multipath effects, Very Long Baseline Interferometry (VLBI) and Satellite Laser Ranging (SLR). The 'serial scheme' based on using GPS as a seismometer has been proposed. Simulated seismic signals have been extracted from the very noisy high rate RTK-GPS results using an adaptive filter based on the least-mean-square algorithm. They are in very good agreement with those of the collocated seismometers. This scheme can improve the CGPS temporal resolution to 0.1 second. The 'retro-active scheme' takes advantage of the fact that the GPS multipath disturbance is repeated between consecutive days. It can therefore provide a means of correcting multipath errors in the observation data themselves. A reduction of the standard deviations of the pseudo-range and carrier phase multipath time series to about one fourth and one half the original values respectively, has been demonstrated. The 'all-GPS parallel scheme' uses the multipath effects as a signal to monitor the antenna environment. Models relating the changes of multipath and antenna environment have been derived. The 'cross-technique parallel scheme' integrates the collocated CGPS, VLBI and SLR results, taking advantage of the decorrelation among their biases and errors. Crustal displacement signature has been extracted as a common-mode signal using data from two stations: Matera in Italy and Wettzell in Germany. Two 'spatial densification schemes' which can verify with each other have been developed and tested. The 'soft' scheme integrates CGPS with radar interferometry (InSAR). The Double Interpolation and Double Prediction (DIDP) approach combines the strengths of the high temporal resolution of CGPS and the high spatial resolution possible with the InSAR technique. This scheme can improve the spatial resolution to about 25m. The 'hard' scheme requires the deployment of single-frequency receivers to in-fill the present CGPS arrays. Alternatively some receivers may be installed at some geophysically strategic sites outside existing CGPS arrays. The former has been tested within Japan's GEONET, while the latter has been tested using a five-station array.

Improving the GPS Data Processing Algorithm for Precise Static Relative Positioning

Satirapod, Chalermchon, Surveying & Spatial Information Systems, Faculty of Engineering, UNSW January 2002 (has links)
Since its introduction in the early 1980????s, the Global Positioning System (GPS) has become an important tool for high-precision surveying and geodetic applications. Carrier phase measurements are the key to achieving high accuracy positioning results. This research addresses one of the most challenging aspects in the GPS data processing algorithm, especially for precise GPS static positioning, namely the definition of a realistic stochastic model. Major contributions of this research are: (a) A comparison of the two data quality indicators, which are widely used to assist in the definition of the stochastic model for GPS observations, has been carried out. Based on the results obtained from a series of tests, both the satellite elevation angle and the signal-to-noise ratio information do not always reflect the reality. (b) A simplified MINQUE procedure for the estimation of the variance-covariance components of GPS observations has been proposed. The proposed procedure has been shown to produce similar results to those from the standard MINQUE procedure. However, the computational load and time are significantly reduced, and in addition the effect of a changing number of satellites on the computations is effectively dealt with. (c) An iterative stochastic modelling procedure has been developed in which all error features in the GPS observations are taken into account. Experimental results show that by applying the proposed procedure, both the certainty and the accuracy of the positioning results are improved. In addition, the quality of ambiguity resolution can be more realistically evaluated. (d) A segmented stochastic modelling procedure has been developed to effectively deal with long observation period data sets, and to reduce the computational load. This procedure will also take into account the temporal correlations in the GPS measurements. Test results obtained from both simulated and real data sets indicate that the proposed procedure can improve the accuracy of the positioning results to the millimetre level. (e) A novel approach to GPS analysis based on a combination of the wavelet decomposition technique and the simplified MINQUE procedure has been proposed. With this new approach, the certainty of ambiguity resolution and the accuracy of the positioning results are improved.

Test av kinematisk Precise Point Positioning i realtid

Jonsson, Fredrik, Jäderberg, Rickard January 2015 (has links)
Utvecklingen av satellitbaserad positionsbestämning gör det idag befogat att begära låga osäkerheter med GNSS. Det är idag möjligt att uppnå osäkerheter kring centimetern. Bäst mätosäkerhet ger relativ mätning som sker med stöd av antingen enkelstations- eller nätverks-RTK. I Sverige erbjuder Lantmäteriet med sitt SWEPOS ett tätt referensnätverk som förser användaren med korrektionsdata oavsett position inom Sveriges gränser. Dock är det inte alla länder som kan erbjuda denna positionstjänst. Geografiskt stora länder har mycket svårt att skapa ett referensnät, det skulle betyda flera tusen stationer och gör det till en ekonomisk fråga. Det är bl.a. ur den synpunkten andra metoder har växt fram. En av dessa är Precise Point Positioning (PPP). Enligt G. Hedling (personlig kommunikation, 18 mars 2015) har PPP fått en väl etablering inom jordbruket samt på maritima gruv- och oljeplattformar. Metoden är lämplig vid stora öppna ytor och när avståndet till närmsta referensstation är stor. PPP använder sig av absolut positionering och kan mäta både statiskt och kinematiskt och resultat kan fås i realtid och genom efterberäkning. Det ligger i Lantmäteriets intresse att testa kinematisk PPP i Sverige och den här studien testar kinematisk PPP i realtid med programvaran BNC 2.11 och med korrektioner från International GPS Service (IGS). Enligt Bisnath & Gao (2009) erhålls decimeterosäkerhet med kinematisk PPP och för att bestämma dess tillförlitlighet har i den här studien koordinatavvikelse beräknats mellan BNC och enkelstations-RTK med stöd från SWEPOS. Koordinaterna från enkelstations-RTK har vid testerna angivits som de sanna koordinaterna, genom ett statiskt test har det undersökts om det är motiverat. Utifrån den statiska mätningen har även intialiseringstiden kunnat utredas, alltså den tid det tar för PPP att konvergera. Efterberäkningstjänsten CSRS-PPP har också testats och jämförts mot kända koordinater vid den statiska mätningen.Studien visar att efter närmare en timmes observation avviker PPP under 2 dm i plan mot enkelstations-RTK. Den visar också att 15-30 minuters konvergeringstid är nödvändig för att erhålla osäkerheter på några decimeter. Några av de faktorer som påverkar resultatet är bl.a. jonosfärstörning. högt PDOP-värde och antal processerade satelliter i mjukvarorna, hur mycket är svårt att säga. Vid en tappad signal krävs en ny omintialisering på flera tiotals minuter. Studien visar också att det är lämpligt att använda enkelstations-RTK som sanning. Vid den statiska mätningen avviker enkelstations-RTK kring centimetern mot den kända punktens koordinater, vilket anses godtagbart. CSRS-PPP uppvisar bra resultat och är inte mycket sämre än det resultat enkelstations-RTK redovisar. / Today it´s possible to achieve low uncertainties when surveying with GNSS. You can expect uncertainties around centimeter-level. The best results are achieved when using relative-surveying with corrections from single-station- or network-RTK. The Swedish mapping, cadastral and land registration authority (Lantmäteriet) is providing a well-developed network of reference stations. The network, called SWEPOS, offers corrections for its users independent of position within the Swedish borders. Far from all nations has the ability or the financial resources to create such an expanded network. Instead, other methods for satellite surveying have been developed, including Precise Point Positioning (PPP). According to G. Hedling (personal communication, 18 march 2015) PPP is well-established in the agriculture and in the maritime mining- and oil-industry. The method is suitable in open areas and it is independently of nearby reference stations. PPP is using what’s called absolute-surveying. The surveying is performed either kinematic or static and the results can be obtained thru post-processing or in real-time. “Lantmäteriet” has interest in testing kinematic PPP in Sweden and for this thesis kinematic PPP in real-time is tested with BNC 2.11 software and corrections is given from the International GPS Service (IGS). According to Bisnath & Gao (2009) it is possible to achieve uncertainties in decimeter-level with kinematic PPP. To determine the reliability of PPP the deviation has been calculated against single-station-RTK. The single-station-RTK coordinates have in this study been used as the “truth” and in an additional test using static measurements it has been investigated if that’s correct. From the static test the initialization time for PPP as well as the quality of the post-processing service CSRS-PPP has been studied.The results show that after nearly an hour of observation the deviation between PPP and single-station-RTK are below 2 dm for the level-coordinates. The initialization time of 15-30 minutes is necessary to achieve uncertainties of a few decimeters. Elements that are affecting the results are disturbance in the ionosphere, high PDOP and number of processed satellites in the software. In which extent it’s not possible to determine. When the signal is lost between rover and satellites a re-initialization of 15-30 minutes is needed. It also shows that it is reasonable to use single-station-RTK as the “truth”. Single-station-RTK deviates a proximately one centimeter in relation to known coordinates. The post-processing service CSRS-PPP gives remarkably good results not far from what single-station-RTK offers.

Kungafamiljens sommarparadis, en pärla på Öland : En fallstudie om Sollidens slott och dess image, varumärke och positionering

Rosén, Charlotte, Stenborg, Susanna January 2015 (has links)
This essay is based on a mission from Anna Schibli, Director of Tourism at Solliden Palace. The thesis aims to investigate the image that Solliden Palace has, and the picture that local and regional tourist offices have of the Sollidens Castle brand and what position Solliden include in these markets. A total of six in-depth interviews with tourist offices, at local and regional level, has been carried out and an initial in-depth interview with Anna Schibli of Solliden Palace. The responses of the respondents have since been interpreted and processed based on an inductive approach, in order to interpret the image that Solliden Palace has. Scientific papers have been studied and analyzed in order to generate an explanation and understanding of the research area. The collected empirical data has mainly consisted of a total of six interviews with tourist offices, and represents the image as it appears that Solliden has. The results of the thesis showed that Sollidens castle's image is relatively weak, when it emerged that few tourists know the whole Sollidens brand / concept. This may be due that a sufficiently effective marketing is not conducted by Solliden Palace. The results showed that Sollidens position in the market is seen as unique by tourists because of the royal family, but because of the weak marketing and knowledge of all parts of Sollidens castle, we identified that it is not a strong market position. However does Solliden Palace sees as a special and unique place, so with the right marketing, it can mean a major boost for Solliden.

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