Vehicle location and tracking has a variety of commercial applications and none of the techniques currently used can provide accurate results in all situations. This thesis details a preliminary investigation into a new location estimation method which uses optical environmental data, gathered by the vehicle during motion, to locate and track vehicle positions by comparing said data to pre-recorded optical maps of the intended location space. The design and implementation of an optical data recorder is presented. The map creation process is detailed and the location algorithm, based on a particle filter, is described in full. System tests were performed offline on a desktop PC using real world data collected by the data recorder and their results are presented. These tests show good performance for the system tracking the vehicle once its approximate location is determined. However locating a vehicle from scratch appears to be infeasible in a realistically large location space.

by Wong Ching-man. / Thesis (M.Ph.)--Chinese University of Hong Kong, 1984 / Bibliography: leaves 160-165.

Largely driven by advances in communication and information technology, such as the increasing availability and accuracy of GPS technology and the miniaturization of wireless communication devices, Location–Based Services (LBS) are continuously gaining popularity. Innovative LBSes integrate knowledge about the users into the service. Such knowledge can be derived by analyzing the location data of users. Such data contain two unique dimensions, space and time, which need to be analyzed. The objectives of this thesis are three–fold. First, to extend popular data mining methods to the spatio–temporal domain. Second, to demonstrate the usefulness of the extended methods and the derived knowledge in two promising LBS examples. Finally, to eliminate privacy concerns in connection with spatio–temporal data mining by devising systems for privacy–preserving location data collection and mining.   To this extent, Chapter 2 presents a general methodology, pivoting, to extend a popular data mining method, namely rule mining, to the spatio–temporal domain. By considering the characteristics of a number of real–world data sources, Chapter 2 also derives a taxonomy of spatio–temporal data, and demonstrates the usefulness of the rules that the extended spatio–temporal rule mining method can discover. In Chapter 4 the proposed spatio–temporal extension is applied to find long, sharable patterns in trajectories of moving objects. Empirical evaluations show that the extended method and its variants, using high–level SQL implementations, are effective tools for analyzing trajectories of moving objects. Real–world trajectory data about a large population of objects moving over extended periods within a limited geographical space is difficult to obtain. To aid the development in spatio–temporal data management and data mining, Chapter 3 develops a Spatio–Temporal ACTivity Simulator (ST–ACTS). ST–ACTS uses a number of real–world geo–statistical data sources and intuitive principles to effectively generate realistic spatio–temporal activities of mobile users.   Chapter 5 proposes an LBS in the transportation domain, namely cab–sharing. To deliver an effective service, a unique spatio–temporal grouping algorithm is presented and implemented as a sequence of SQL statements. Chapter 6 identifies ascalability bottleneck in the grouping algorithm. To eliminate the bottleneck, the chapter expresses the grouping algorithm as a continuous stream query in a data stream management system, and then devises simple but effective spatio–temporal partitioning methods for streams to parallelize the computation. Experimental results show that parallelization through adaptive partitioning methods leads to speed–ups of orders of magnitude without significantly effecting the quality of the grouping. Spatio–temporal stream partitioning is expected to be an effective method to scale computation–intensive spatial queries and spatial analysis methods for streams.   Location–Based Advertising (LBA), the delivery of relevant commercial information to mobile consumers, is considered to be one of the most promising business opportunities amongst LBSes. To this extent, Chapter 7 describes an LBA framework and an LBA database that can be used for the management of mobile ads. Using a simulated but realistic mobile consumer population and a set of mobile ads, the LBA database is used to estimate the capacity of the mobile advertising channel. The estimates show that the channel capacity is extremely large, which is evidence for a strong business case, but it also necessitates adequate user controls.   When data about users is collected and analyzed, privacy naturally becomes a concern. To eliminate the concerns, Chapter 8 first presents a grid–based framework in which location data is anonymized through spatio–temporal generalization, and then proposes a system for collecting and mining anonymous location data. Experimental results show that the privacy–preserving data mining component discovers patterns that, while probabilistic, are accurate enough to be useful for many LBSes.   To eliminate any uncertainty in the mining results, Chapter 9 proposes a system for collecting exact trajectories of moving objects in a privacy–preserving manner. In the proposed system there are no trusted components and anonymization is performed by the clients in a P2P network via data cloaking and data swapping. Realistic simulations show that under reasonable conditions and privacy/anonymity settings the proposed system is effective. / QC 20120215

Due to the availability of the cellular phone, PCS (Personal Communication Service) has become wildly popular world-wide [1], and the number of the PCS users has quickly grown beyond what anyone had imagined. As its name indicates, mobility is the most remarkable feature of a cellular phone. On the other hand, that means it is difficult to determine the location of the PCS users. The proficiency to determine the geographical position of a cellular phone users have become increasingly important. One main reason for this service is the use of mobile phones for emergency calls, which is expected to grow quickly in the near future. For emergency assistance via 911 (Emergency 911, E-911), the FCC (Federal Communications Commission) has now required that system operators of mobile communications networks be able to accurately locate mobile callers before year 2001. There has been a lot of ongoing research examining cellular positioning options among cellular and PCS providers. Most location approaches require measurements at multiple receiving stations or need supports from base stations. Our main proposal in this paper is a new approach to enhance the performance of wireless position location through a single cellular phone. This method has the following two features: First, it does not require any modification to the current GSM (Global System for Mobile Communication) architecture, that is, it does not increase network traffic. Second, the location identifications is performed on the mobile end, which does not increase computation load of the network system. Hence, the quantity of self-location cellular phones which can be supported by GSM system has no upper limit. In this sense, we would say that Cell Base Automatic Location Identification System is a method worthy of further exploration. Meanwhile, this technique could be applied on the other domains, such as electron-map, local resource detected, newfangled chat room, controlling caller¡¦s location, etc. The intention of this paper is to introduce innovation uses single cellular phone to implement ALI (Automatic Location Identification) system. The whole issue determining the TA (Timing Advance) between the MS (Mobile Station) and the BTS (Base Transference Station) as well as coupling the calculated distance with the determined direction of the BTS signal so as to calculate the location of the MS. To counter the inaccuracies of the ALI system, we offer a force-handover subfunction. Even though one or more force-handovers increase the accuracy, the cost is extra time overhead. In our location system, we implement two applications to determine the reliability of any ALI system information. They are Wireless Signed System and Resources Information Searching System.

Thesis (M.A.)--University of Hong Kong, 1974.

published_or_final_version / Urban Studies / Master / Master of Social Sciences

No description available.

No description available.

No description available.

The current technology used for location of permanent faults in high voltage direct current (HVDC) transmission lines and cables is based on the travelling-wave principle. This technology has served well for the conventional point-to-point HVDC systems, but is inadequate to handle emerging HVDC transmission configurations such as schemes with very long overhead lines or cables, schemes with a combination of cable and overhead line segments, and multi-terminal HVDC (MTHVDC) schemes. This research investigated accurate and economical ways to locate the faults on dc transmission lines in the aforementioned emerging HVDC transmission configurations. The accuracy of travelling-wave based fault location methods is highly dependent on the accuracy of measuring the time of arrival of the fault generated travelling waves. Investigations showed that post-processing of detection signals such as the line terminal voltages or surge capacitor currents with continuous wavelet transform yields consistent and accurate fault location results. This method was applied for fault location in HVDC systems with extra-long overhead lines and cables using only the terminal measurements. Simulation results verified the effectiveness of this method in locating the faults in a 2400 km long overhead line and a 300 km long underground cable. A new algorithm was proposed to locate the faults in a two-terminal HVDC system consisting of multiple segments of overhead lines and cables, using only the terminal measurements. Application of the proposed algorithm was analysed through detailed simulations. Correct performance was verified under various scenarios. A new algorithm was developed for locating the faults in a star-connected MTHVDC network. This algorithm is also required only the terminal measurements. Its effectiveness was verified through detailed simulations. Finally, a novel measurement scheme for detection of travelling-wave arrival times was proposed. A prototype of this measurement scheme which uses a Rogowski coil to measure the transient currents through the surge capacitors at the line terminals was implemented. Its effectiveness was validated through field tests in a real HVDC transmission system. The proposed measurement scheme could capture significantly clean signals in an actual substation environment, confirming the practicability of implementing the proposed new algorithms.