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Impact of event positioning algorithm on performance of a whole-body PET scanner using one-to-one coupled detectors

PHYSICS IN MEDICINE AND BIOLOGY 2018年第5期63卷 055008-055008页

作者： Surti, S. Karp, J. S. Univ Penn Dept Radiol Philadelphia PA 19104 USA Univ Penn Dept Phys & Astron Philadelphia PA 19104 USA

The advent of silicon photomultipliers (SiPMs) has introduced the possibility of increased detector performance in commercial whole-body PET scanners. The primary advantage of these photodetectors is the ability to couple a single SiPM channel directly to a single pixel of PET scintillator that is typically 4 mm wide (one-to-one coupled detector design). We performed simulation studies to evaluate the impact of three different event positioning algorithms in such detectors: (i) a weighted energy centroid positioning (Anger logic), (ii) identifying the crystal with maximum energy deposition (1st max crystal), and (iii) identifying the crystal with the second highest energy deposition (2nd max crystal). Detector simulations performed with LSO crystals indicate reduced positioning errors when using the 2nd max crystal positioning algorithm. These studies are performed over a range of crystal cross-sections varying from 1 x 1 mm2 to 4 x 4 mm(2) as well as crystal thickness of 1 cm to 3 cm. System simulations were performed for a whole-body PET scanner (85 cm ring diameter) with a long axial FOV (70 cm long) and show an improvement in reconstructed spatial resolution for a point source when using the 2nd max crystal positioning algorithm. Finally, we observe a 30-40% gain in contrast recovery coefficient values for 1 and 0.5 cm diameter spheres when using the 2nd max crystal positioning algorithm compared to the 1st max crystal positioning algorithm. These results show that there is an advantage to implementing the 2nd max crystal positioning algorithm in a new generation of PET scanners using one-to-one coupled detector design with lutetium based crystals, including LSO, LYSO or scintillators that have similar density and effective atomic number as LSO.

关键词： PET positioning algorithm spatial resolution contrast one-to-one coupled detector

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positioning algorithm For Wireless Capsule Endoscopy Based on RSS 16

Positioning Algorithm For Wireless Capsule Endoscopy Based o...

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16th IEEE International Conference on Ubiquitous Wireless Broadband (ICUWB)

作者： Wang, Hao Zhang, Yerong Yu, Xiaojie Wang, Guanyun Nanjing Univ Posts & Telecommun Nanjing Jiangsu Peoples R China

ISBN: (纸本)9781509013173

A large quantity of disorders that occur in the gastrointestinal tract have always been challenging to be diagnosed in a complex environment inside the human body, but with the invention and development of wireless capsule endoscope. Many patients that experienced traditional treatment will perceive stupendous convenience. Such wireless capsule endoscope requires a highly accurate localization system. The paper presents a positioning algorithm of internal the human body's capsule endoscope. The idea is to measure electromagnetic power by the capsule emitted that through the human body, and positioning the exact location of the capsule endoscope. The algorithm has been developed and simulated on MATLAB. Simulation results demonstrate it's highly accurateness.

关键词： Wireless Capsule Endoscopy positioning algorithm Simulation

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Research on Location Fingerprint Based WiFi positioning algorithm

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电脑学刊 2017年第5期28卷 162-177页

作者： Maoyuan Huang Shaobo Wu Yinglei Li

Existing WiFi signals are utilized to carry out indoor positioning, and received signal strength RSSI is usually selected as a positioning feature parameter. An RSSI positioning algorithm is divided into a range-based positioning algorithm and a range-free positioning algorithm. The range-based positioning algorithm calculates a distance by utilizing an indoor transmission loss model and is lager in dependency on an indoor model; and the range-free positioning algorithm adopts a location fingerprint algorithm, a fingerprint database is established by only needing to measure RSSI values, each fingerprint is in only correspondence to one location information, information of an unknown location can be estimated by matching the unknown location fingerprint and the fingerprint database, and realization is simple. This article studies the positioning principle of the location fingerprint algorithm, indicates influence factors which may generate errors in the positioning process, comprehensively and deeply analyzes sources of the errors and also indicates the limitation of the existing location estimation algorithm. This article presents a k-means and WKNN based location fingerprint algorithm. According to the location fingerprint algorithm, the fingerprint database is preliminarily established by measuring collected RSSI values for many times and solving a mean and then is trained by utilizing k-means clustering analysis, and some fingerprints with very small similarity are removed; and actually measured fingerprints are matched with the fingerprint database after being trained, so that the accuracy of the fingerprint database is improved, the search space of matching is reduced, and the influence of the fingerprint database on a positioning result is reduced. In the location estimation stage, a new weight coefficient calculation method is introduced, the location accuracy of WKNN is improved.

关键词： clustering fingerprint k-means positioning algorithm RSSI WiFi WKNN WLAN

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An Improved positioning algorithm in a Long-Range Asymmetric Perimeter Security System

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JOURNAL OF LIGHTWAVE TECHNOLOGY 2016年第22期34卷 5278-5283页

作者： Liu, Kun Tian, Miao Jiang, Junfeng An, Jianchang Xu, Tianhua Ma, Chunyu Pan, Liang Wang, Tao Li, Zhichen Zheng, Wenjie Xue, Meng Wu, Fan Liu, Tiegen Tianjin Univ Minist Educ Coll Precis Instrument & Optoelect Engn Tianjin 300072 Peoples R China Tianjin Univ Minist Educ Key Lab Optoelect Informat Technol Tianjin 300072 Peoples R China UCL Dept Elect & Elect Engn London WC1E 6BT England

In this paper, an improved positioning algorithm is proposed for a long-range asymmetric perimeter security system. This algorithm employs zero-crossing rate to detect the disturbance starting point, and then utilizes an improved empirical mode decomposition to obtain the effective time-frequency distribution of the extracted signal. In the end, a cross-correlation is used to estimate the time delay of the effective extracted signal. The scheme is also verified and analyzed experimentally. The field test results demonstrate that the proposed scheme can achieve a detection of 96.60% of positioning errors distributed within the range of 0- +/- 20 m at the sensing length of 75 km, which significantly improves the positioning accuracy for the long-range asymmetric fence perimeter application.

关键词： Asymmetric dual Mach-Zehnder interferometer (ADMZI) empirical mode decomposition (EMD) fiber optic distributed sensor positioning algorithm signal analysis

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A High-precision TOA-based positioning algorithm Without the Restriction of Strict Time Synchronization for Wireless Systems 13

A High-precision TOA-based Positioning Algorithm Without the...

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13th IEEE International Conference on Signal Processing (ICSP)

作者： Kang Yimei Wang Jiawei Beihang Univ Coll Software Beijing Peoples R China

ISBN: (纸本)9781509013456

Time-of-arrival (TOA) is a range-based positioning method with high positioning precision. However, TOA-based methods require strict time synchronization between nodes, which puts forward high requirements on the hardware and power consumption of sensor nodes. For the high cost hardware problem of TOA-based methods, we propose a TOA-based iterative algorithm (iTOA) that can be applied to the wireless system under the condition of low time synchronization precision to achieve high positioning precision. Without the restriction of strict time synchronization, iTOA can reduce the difficulty of hardware implementation. iTOA eliminates the time synchronization error via iteration and minimizes the non-line-of-sight propagation error by using the weighted least square method at the same time. Moreover, iTOA can be applied to the network with changing beacons. The simulation results show that the average positioning precision improves at least 27.2% and 38.3% compared to CCTG and LOP, respectively. As the time synchronization precision decreases, the positioning precision improvement is more obvious compared to CCTG and LOP. For a low time synchronization precision system, the positioning error of iTOA is almost 99.99% less than both CCTG and LOP.

关键词： positioning algorithm TOA time synchronization precision iteration

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Enhanced positioning algorithm of ARPS for Improving Accuracy and Expanding Service Coverage

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SENSORS 2016年第8期16卷 1284-1284页

作者： Lee, Kyuman Baek, Hoki Lim, Jaesung Ajou Univ Dept Comp Engn 206 World Cup Ro Suwon 16499 South Korea Ajou Univ Dept Mil Digital Convergence 206 World Cup Ro Suwon 16499 South Korea

The airborne relay-based positioning system (ARPS), which employs the relaying of navigation signals, was proposed as an alternative positioning system. However, the ARPS has limitations, such as relatively large vertical error and service restrictions, because firstly, the user position is estimated based on airborne relays that are located in one direction, and secondly, the positioning is processed using only relayed navigation signals. In this paper, we propose an enhanced positioning algorithm to improve the performance of the ARPS. The main idea of the enhanced algorithm is the adaptable use of either virtual or direct measurements of reference stations in the calculation process based on the structural features of the ARPS. Unlike the existing two-step algorithm for airborne relay and user positioning, the enhanced algorithm is divided into two cases based on whether the required number of navigation signals for user positioning is met. In the first case, where the number of signals is greater than four, the user first estimates the positions of the airborne relays and its own initial position. Then, the user position is re-estimated by integrating a virtual measurement of a reference station that is calculated using the initial estimated user position and known reference positions. To prevent performance degradation, the re-estimation is performed after determining its requirement through comparing the expected position errors. If the navigation signals are insufficient, such as when the user is outside of airborne relay coverage, the user position is estimated by additionally using direct signal measurements of the reference stations in place of absent relayed signals. The simulation results demonstrate that a higher accuracy level can be achieved because the user position is estimated based on the measurements of airborne relays and a ground station. Furthermore, the service coverage is expanded by using direct measurements of reference stations for user p

关键词： accuracy enhancement re-estimation positioning algorithm virtual measurement dilution of precision

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An Improved positioning algorithm With High Precision for Dual Mach-Zehnder Interferometry Disturbance Sensing System

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JOURNAL OF LIGHTWAVE TECHNOLOGY 2015年第10期33卷 1954-1960页

作者： Chen, Qinnan Liu, Tiegen Liu, Kun Jiang, Junfeng Shen, Zhe Ding, Zhenyang Hu, Haofeng Huang, Xiangdong Pan, Liang Ma, Chunyu Tianjin Univ Coll Precis Instrument & Optoelect Engn Tianjin 300072 Peoples R China Univ Liverpool Dept Elect Engn & Elect Liverpool L69 3GJ Merseyside England Tianjin Univ Sch Elect Informat Engn Tianjin 300072 Peoples R China

An improved positioning algorithm for dual Mach-Zehnder interferometry (DMZI) disturbance sensing system is proposed. We employ zero-crossing method, which can be computed easily to extract the disturbance signal segment with maximum zero-crossing rate. Meanwhile, we use general cross correlation based on Wiener filtering and G(nn) subtraction weighting function (WG-GCC) to estimate the time delay of the extracted signal, which is robust to the correlated noise. Finally, we experimentally demonstrate that the proposed positioning algorithm can greatly improve the positioning accuracy with positioning error of +/- 20 m. Compared with the traditional positioning algorithm, the positioning error has been reduced by an order of magnitude. This algorithm has a promising potential in real-time fence perimeter applications.

关键词： Distributed fiber-optic sensor fence perimeter application general cross correlation positioning algorithm zero-crossing rate

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A High-precision TOA-based positioning algorithm Without the Restriction of Strict Time Synchronization for Wireless Systems

A High-precision TOA-based Positioning Algorithm Without the...

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2016 IEEE 13th International Conference on Signal Processing（ICSP2016）

作者： Kang Yimei Wang Jiawei College of software Beihang University

Time-of-arrival(TOA) is a range-based positioning method with high positioning precision. However, TOA-based methods require strict time synchronization between nodes, which puts forward high requirements on the hardware and power consumption of sensor nodes. For the high cost hardware problem of TOA-based methods, we propose a TOA-based iterative algorithm(i TOA) that can be applied to the wireless system under the condition of low time synchronization precision to achieve high positioning precision. Without the restriction of strict time synchronization, i TOA can reduce the difficulty of hardware implementation. i TOA eliminates the time synchronization error via iteration and minimizes the non-lineof-sight propagation error by using the weighted least square method at the same time. Moreover, iT OA can be applied to the network with changing beacons. The simulation results show that the average positioning precision improves at least 27.2% and 38.3% compared to CCTG and LOP, respectively. As the time synchronization precision decreases, the positioning precision improvement is more obvious compared to CCTG and LOP. For a low time synchronization precision system, the positioning error of i TOA is almost 99.99% less than both CCTG and LOP.

关键词： positioning algorithm TOA time synchronization precision iteration

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A positioning algorithm for two-wavelength dual Mach-Zehnder interferometry vibration sensing system

A positioning algorithm for two-wavelength dual Mach-Zehnder...

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International Conference on Optical Instruments and Technology - Optical Sensors and Applications

作者： Ma, Chunyu Liu, Tiegen Liu, Kun Jiang, Junfeng Chen, Qinnan Pan, Liang Chai, Tianjiao He, Chang Tianjin Univ Key Lab Optoelect Informat Technol Tianjin 300072 Peoples R China

ISBN: (纸本)9781628418019

A positioning algorithm for two-wavelength dual Mach-Zehnder interferometry (TDMZI) vibration sensing system is proposed. We employ the reciprocal of the interval between neighboring zero-crossing (NZC) points to represent the frequency distribution of the interference signal in time domain. Meanwhile, these reciprocal points are used to fit a curve and we use cross correlation to estimate the time delay of the two fitted curves. Finally we analysis the positioning error caused by the proposed positioning algorithm and experimentally demonstrate that the algorithm can be used to locating with positioning error of +/-50m. This algorithm has a promising potential in long distance two-wavelength vibration sensing system.

关键词： Two-Wavelength Dual Mach-Zehnder positioning algorithm error analysis vibration measurement

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Semi-supervised positioning algorithm in Indoor WLAN Environment

Semi-supervised Positioning Algorithm in Indoor WLAN Environ...

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81st IEEE Vehicular Technology Conference (VTC Spring)

作者： Ying, Xia Lin, Ma Zhang Zhongzhao Yao, Wang Harbin Inst Technol Commun Res Ctr Harbin 150006 Peoples R China Qiqihar Univ Sch Commun & Elect Engn Qiqihar Peoples R China Minist Publ Secur Key Lab Police Wireless Digital Commun Harbin Peoples R China

ISBN: (纸本)9781479980888

In Wireless Local Area Network (WLAN) positioning system, the most popular solution for RSS-based positioning is the fingerprinting architecture. In this paper, we present a novel algorithm, known as Semi-supervised Discriminant Embedding (SDE), to reconstruct a radio map by using real-time signal-strength values received at random points. Instead of deploying dense reference points, our approach takes advantage of less labeled data and partial unlabeled data to transform into lower-dimensional feature signals. Through solving the objective functions optimization, with strong discriminative features in Receive Signal Strength (RSS) are retained in the low-dimensional space. We conducted experiments in our office area with a realistic WLAN environment. Compared to the traditional methods, the experimental results show that the proposed algorithm has considerable accuracy improvement in the same positioning environment. Furthermore, the results also show the size of training samples can be greatly reduced in the proposed algorithm in order to achieve the similar accuracy of traditional approaches. That is, the cost of collecting fingerprints in the offline stage and calibrating database in the online stage are thus reduced.

关键词： Wireless local area network (WLAN) Fingerprinting Semi-supervised discriminant embedding (SDE) Dimensional reduction positioning algorithm

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