Observability of Airborne Passive Location System with Phase Difference Measurements

With a pair of antennas spaced apart, an airborne passive location system measures phase differences of emitting signals. Regarded as cyclic ambiguities, the moduli of the measurements traditionally are resolved by adding more antenna elements. This paper models the cyclic ambiguity as a component of the system state, of which the observability is analyzed and compared to that of the bear- ings-only passive location system. It is shown that the necessary and sufficient observability condition for the bearings-only passive location system is only the necessary observability condition for the passive location system with phase difference measurements, and that when the system state is observable, the cyclic ambiguities can be estimated by accumulating the phase difference measurements, thereby making the observer able to locate the emitter with high-precision.

New multi-layer data correlation algorithm for multi-passive-sensor location system

Under the scenario of dense targets in clutter, a multi-layer optimal data correlation algorithm is proposed. This algorithm eliminates a large number of false location points from the assignment process by rough correlations before we calculate the correlation cost, so it avoids the operations for the target state estimate and the calculation of the correlation cost for the false correlation sets. In the meantime, with the elimination of these points in the rough correlation, the disturbance from the false correlations in the assignment process is decreased, so the data correlation accuracy is improved correspondingly. Complexity analyses of the new multi-layer optimal algorithm and the traditional optimal assignment algorithm are given. Simulation results show that the new algorithm is feasible and effective.

Multilayer ANN indoor location system with area division in WLAN environment

An indoor location system based on multilayer artificial neural network（ANN） with area division is proposed.The characteristics of recorded signal strength（RSS）,or signal to noise ratio（SNR） from each available access points（APs）,are utilized to establish the radio map in the off-line phase.And in the on-line phase,the two or three dimensional coordinates of mobile terminals（MTs） are estimated according to the similarity between the new recorded RSS or SNR and fingerprints pre-stored in radio map.Although the feed-forward ANN with three layers is sufficient to describe any nonlinear mapping relationship between inputs and outputs with finite discontinuous points,the efficient inputs for better training performances are difficult to be determined because of complex and dynamic indoor environment.Then,the discussion of distance relativity for different signal characteristics and optimal strategies for multi-mode phenomenon avoidance is presented.And also,the feasibility and effectiveness of this method are verified based on the experimental comparison with normal ANN without area division,K-nearest neighbor（KNN） and probability methods in typical office environment.

Power Network Lightning Accident Quick Inquiry with the Lightning Location System

At present, lightning is one of the 10 natural disasters, and it is also the top environmental factor of power interruption. It often causes huge losses to the electric system. The Wuhan High Voltage Institute of the State Grid Corporation of China and Huazhong University of Science and Technology have been researching and developing lightning location systems （LLSs） since the late 1980s. In the mid-1990s, a lightning detection network was created in 29 provinces and cities in China. It is primarily applied to rapidly find lightning accidents, which greatly reduces power interruption. Also, it ensures high efficiency and safe operation of the electricity system. Remarkable benefit is achieved. China＇s LLS went through an ＂orientation positioning - time difference positioning - integrated positioning＂ development process. The positioning precision, detection efficiency, degree of automation, practicability and applied range are improved. Also, a lightning information system plan of the national network has been implemented, which services the whole society.

ACCURACY ANALYSIS OF PASSIVE LOCATION SYSTEM WITH PHASE DIFFERENCE RATE MEASUREMENT

The conventional mono-station passive location techniques of direction finding are low in speed and accuracy, due to the little information available. In this paper, a novel measurement-rate (derivative) of phase difference from a two-element antenna array (interferometer) is introduced, accuracy of a passive location system with this measurement and directions of arrival (DOA) is analyzed, and the Cramer-Rao bound of location error of this system for 3D location is examined by simulations.

Application of Data from a Lightning Location System in Huai'an Region

Based on data of cloud-to-ground lightning detected by a lightning location system in Jiangsu Province from 2007 to 2012and data of thunderstorm days from seven meteorological observation stations in Huai'an during 1961-2012,the spatial and temporal distribution characteristics of cloud-to-ground lightning in Huai'an were analyzed.The results show that the total frequency of cloud-to-ground lightning in one day was closely related to the intensity and frequency of thunder and lightning.The seasonal variations in the total frequency of cloud-to-ground lightning in Huai'an.The total frequency was shown in unimodal distribution,and the extreme values always appeared in July or August.Most cloud-to-ground lightning was negative,and its frequency accounted for about95.3% of the total frequency.Cloud-to-ground lightning density was high in the south of Huai'an and low in the north,and the serious and very serious ground flash zones concentrated in the south of Hongze County,and most parts of Xuyi and Jinhu County,so lightning protection should be an important task particularly in these regions.

High Performance of a TOA-TDOA Hybrid GSM Location System for Intelligent Transportation Systems

This paper illustrates the performance of a mobile positioning technique applicable to a GSM network.An experimental system of a network-based GSM positioning for ITS has been proposed, and the hybrid TOA-TDOA method based on GSM signaling has been analyzed and used. The performance of the proposed system is showed through simulations in urban and suburban environments. The accuracy for 67% mobile stations is 70 m in urban and 120 m in suburban. The accuracy, coverage and network load of positioning system are also analyzed.

Design and Implementation of Lightning Analysis Software Based on Lightning Location System Data

This paper discusses the steps about how to design and implement software based on lightning location system data and its localization map.The system contains four major modules such as real-time lightning monitoring,historical query,lightning intensity zoning,lightning disaster statistics,etc.The system is able to automatically generate real-time lightning monitoring image,lightning animation,and lightning intensity zoning image,which contributes to the high accuracy of the calculation results and the efficiency of data analysis.The paper also points out the deficiencies of software life cycle management and proposes actionable solutions.

FAULT LOCATION AND RECORDING SYSTEM OF TRANSMISSION LINES BASED ON COMPUTER NETWORK

In this paper a fault location and recording system based on a computer network is presented. A brief description of the system structure and main features are given. Emphasis is placed on the accurate fault location method for extra high voltage and long distance transmission lines.

A PARAMETRIC METHOD OF SITE ERROR ESTIMATION FOR A LIGHTNING LOCATION SYSTEM

In this paper,a parametric method of site error estimation is developed for a lightning location system (LLS) which consists of three or more direction finders (DFs) and one position analyzer (PA). The site error for each DF is a function of bearings measured by the DF, and is assumed to be limited-term harmonics. The problem of site error estimation is reduced to a non-linear unconstrained minimization problem by employing the eigen technique (Orville Jr., 1987). The site error can be found directly by minimizing the objective function. By using the data set obtained with the LLS of three DFs in Beijing area during the summer of 1988, the site error correction curves for all DFs were found. About 4900 lightning flashes detected by the three DFs were used. The results showed that about 95% of the flash residuals of the sample were within ± 1 degree after corrections. The lightning locations with site error corrections were more consistent with the corresponding radar echoes than those without corrections.

New optimal algorithm of data association for multi-passive-sensor location system

In dense target and false detection scenario of four time difference of arrival （TDOA） for multi-passive-sensor location system, the global optimal data association algorithm has to be adopted. In view of the heavy calculation burden of the traditional optimal assignment algorithm, this paper proposes a new global optimal assignment algorithm and a 2-stage association algorithm based on a statistic test. Compared with the traditional optimal algorithm, the new optimal algorithm avoids the complicated operations for finding the target position before we calculate association cost; hence, much of the procedure time is saved. In the 2-stage association algorithm, a large number of false location points are eliminated from candidate associations in advance. Therefore, the operation is further decreased, and the correct data association probability is improved in varying degrees. Both the complexity analyses and simulation results can verify the effectiveness of the new algorithms.

TLP bonding of dissimilar FSX-414/IN738 system with MBF80 interlayer: Prediction of solid/liquid interface location

Isothermal solidification process of a dissimilar transient liquid phase （TLP） bonding of FSX-414/MBF80/IN738 system was simulated by finite difference method. The TLP joint model was divided into two parts and a moving liquid /solid interface model was used for the parts. Diffusion equations were solved for each half of the joints simultaneously up to the end of isothermal solidification. The completion time of isothermal solidification, concentration profiles and position of the solid/liquid interface for each half were calculated. The intersection of the solid/liquid interfaces of two halves was considered the end of isothermal solidification. To obtain some required diffusion data, TLP bonding of FSX-414/MBF80/IN738 was performed at different temperature and time under vacuum atmosphere. The calculated results show good agreement with the experimental results.

Design and performance analysis of wireless sensor network location node system for underground mine

Aiming at the application of a wireless sensor network to locating miners in underground mine,we design a wireless sensor network location node system,considering the communication performance and the intrinsic safety. The location node system consists of a mobile node,several fixed nodes,and a sink node,all of whose circuits were designed based on CC2430. A varistor and a RC circuit were used in the reset circuit of a sensor node to guarantee the intrinsic safety by reducing discharge energy,the theoretical analysis of the discharge energy shows that the reset circuit is an intrinsic safety one. The analysis and simulation about the performance of the location node system are discussed,such as network communication delay and packet loss rate,the results show that the highest network communication delay of the system is about 0.11 seconds,and the highest packet loss rate is about 0.13,which assures the location node system has a high reliability,and can locate miners in the underground mine.

Online location of seismic damage to a water distribution system

As one of the most important urban lifeline systems,a water distribution system can be damaged under a strong earthquake,and the damage cannot easily be located,especially immediately after the event.This often causes tremendous difficulties to post-earthquake emergency response and recovery activities.This paper proposes a methodology to locate seismic damage to a water distribution system by monitoring water head online at some nodes in the water distribution system.An artificial neural network-based inverse analysis method is developed to estimate the water head variations at all nodes that are not monitored based on the water head variations at the nodes that are monitored.The methodology provides a quick,effective,and practical way to locate seismic damage to a water distribution system.

Reasonable location parameters of pick and nozzle in combined cutting system

The drum shearer and high pressure water jet combined cutting system is an effective technology to cut hard coal-rock, but one problem of the technology is the choice of pick and nozzle location parameters. In order to solve the problem, the process and mechanism of combined cutting arc studied and mining seepage catastrophe theory is used to construct the mathematic and physical model of combined cutting hard coal-rock. Based on the model and detailed analysis of combined cutting mechanism, the single pick and nozzle combined cutting test-bed is built to test the main pick and nozzle location parameters of drum shearer and water jet combined cutting system. Test results show that the best vertical distance between the pick-tip and nozzle center point is the sum of cutting thickness and proper target distance in the Y axial direction; the best horizontal distance is the length between pick-tip point and coal-rock surface bursting crack point in the X axial direction. The best incident angle of water jet should be the same as the bursting crack line＇s angle in theory, but considering other important factors comprehensively, it is more reasonable when the incident angle of water jet is 90°.

Impact of primary tumour location on colorectal liver metastases: A systematic review

BACKGROUND Colorectal cancer(CRC)is the third most common cause of cancer-related death worldwide.Despite significant advances in screening,surgical management and adjuvant therapies,average 5-year survival seldom exceeds 60%in most developed nations.Metastatic disease represents the primary cause of mortality in patients with CRC,and the liver is the most common location for distant tumour spread.Up to 25%of patients are found to have synchronous liver metastases at the time of diagnosis and a further 30%-40%will develop metachronous disease in the course of follow-up.It has been suggested that primary tumour location[right side versus left side,primary tumour location(PTL)]can influence oncological outcomes in this patient group and that this should be considered in prognostic models and therapeutic decision-making algorithms.This suggestion is not universally accepted and there have been conflicting reports in the literature to date.AIM To provide a comprehensive summary of the available evidence regarding the impact of PTL on oncological outcomes in patients with colorectal cancer liver metastases(CRCLM).METHODS MEDLINE,EMBASE and COCHRANE were searched for relevant publications using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses methodology.Data on oncological outcomes was then extracted from full text articles that met the predefined inclusion criteria.RESULTS A total of 41 studies were identified that met predefined inclusion criteria for this review.In 21 out of 38 studies that provided data on overall survival,a statistically significant improvement in overall survival was reported in patients with left sided primary tumours.These studies included a total of 13897 patients compared with 4306 patients in the studies that did not show a significant difference.Eight studies noted a similar trend towards improved disease-free or progression-free survival.Several authors observed distinct patterns of relapse after treatment of hepatic metastases according to PTL;for example hepatic recurrence after treatment of CRCLM appears to occur more aggressively with right-sided CRC.CONCLUSION Taken together,the findings of the present review indicate that PTL may have a role as an independent prognostic factor when determining treatment and disease surveillance strategies in CRC.The mechanisms responsible for this variation remain poorly understood,but are likely to relate to molecular,histological and embryological differences,as well as inherent differences in therapeutic sensitivity.

Wireless Location Determination for Mobile Objects Based on GSM in Intelligent Transportation Systems

The mobile object (MO) location determination technologies which can be used in intelligent transportation system (ITS) are studied in this paper. The principles and characteristics of wireless location determination technologies are introduced and the characteristics of GSM useful for location determination are also summarized. An experimental positioning system based on GSM is proposed, and the architecture is described. TOA method based on GSM signals and TDOA method are used in the experimental system. Moreover, the methods are simulated. The performance of the positioning methods is assessed in the simulation environment, and the accuracy for 67% mobile stations (MS) is 70m in urban areas.

Location Verification Systems in Emerging Wireless Networks

As location-based techniques and applications have become ubiquitous in emerging wireless networks, the verification of location information has become more important. In recent years, there has been an explosion of activity related to lo- cation-verification techniques in wireless networks. In particular, there has been a specific focus on intelligent transport systems because of the mission-critical nature of vehicle location verification. In this paper, we review recent research on wireless location verification related to vehicular networks. We focus on location verification systems that rely on for- mal mathematical classification frameworks and show how many systems are either partially or fully encompassed by such frameworks.

Simulation of distributed optical fiber disturbance detection system based on Sagnac/Mach-Zehnder interferometer and cross-correlation location

A distributed optical fiber disturbance detection system consisted of a Sagnac interferometer and a Mach-Zehnder interferometer is demonstrated. Two interferometers outputs are connected to an electric band-pass filter via a detector respectively. The central frequencies of the two filters are selected adaptively according to the disturbance frequency. The disturbance frequency is obtained by either frequency spectrum of the two interferometers outputs. An alarm is given out only when the Sagnac interferometer output is changed. A disturbance position is determined by calculating a time difference with a cross-correlation method between the filter output connected to the Sagnac interferometer and derivative of the filter output connected to the Mach-Zehnder interferometer. The frequency spectrum, derivative and cross-correlation are obtained by a signal processing system. Theory analysis and simulation results are presented. They show that the system structure and location method are effective, accurate, and immune to environmental variations.

Location Service Information Supporting System Based on Ontology

In order to solve the problem of how to collect and manage large amount of location information and improve the accuracy of location service, interactive information supporting system based on ontology and location service is presented in this paper. It can transmit special information about users＇ location to front-end instantaneously, so it is very convenient for their daily life. It makes full use of the available wireless communication, which is easy to arrange and convenient for users.