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Assessment of the Contrast to Noise Ratio in PET Scanners with Monte Carlo Methods

Journal of Physics: Conference Series 2015年第1期637卷

作者： C M Michail G E Karpetas G P Fountos I G Valais D Nikolopoulos I S Kandarakis G S Panayiotakis Radiation Physics Materials Technology and Biomedical Imaging Laboratory Department of Biomedical Engineering Technological Educational Institute of Athens Egaleo 122 10 Athens Greece Department of Medical Physics Faculty of Medicine University of Patras 265 00 Patras Greece Department of Computer Electronic Engineering Technological Education Institute of Piraeus Greece Petrou Ralli & Thivon 250 122 44 Aigaleo Athens Greece

The aim of the present study was to assess the contrast to noise ratio (CNR) of PET scanners through a thin layer chromatography (TLC) plane source. The source was simulated using a previously validated Monte Carlo model. The model was developed by using the GATE MC package and reconstructed images obtained with the STIR software for tomographic image reconstruction. The PET scanner simulated was the GE DiscoveryST. A plane source consisted of a TLC plate, was simulated by a layer of silica gel on aluminum (Al) foil substrates, immersed in 18F-FDG bath solution. Image quality was assessed in terms of the CNR. CNR was estimated from coronal reconstructed images of the plane source. Images were reconstructed by the maximum likelihood estimation (MLE)-OSMAPOSL. OSMAPOSL reconstruction was assessed by using various subsets (3, 15 and 21) and various iterations (2 to 20). CNR values were found to decrease when both iterations and subsets increase. Two (2) iterations were found to be optimal. The simulated PET evaluation method, based on the TLC plane source, can be useful in image quality assessment of PET scanners.

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Influence of Iterative Reconstruction Algorithms on PET Image Resolution

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Journal of Physics: Conference Series 2015年第1期637卷

作者： G E Karpetas C M Michail G P Fountos I G Valais D Nikolopoulos I S Kandarakis G S Panayiotakis Department of Medical Physics Faculty of Medicine University of Patras 265 00 Patras Greece Radiation Physics Materials Technology and Biomedical Imaging Laboratory Department of Biomedical Engineering Technological Educational Institute of Athens Egaleo 122 10 Athens Greece Department of Computer Electronic Engineering Technological Education Institute of Piraeus Greece Petrou Ralli & Thivon 250 122 44 Aigaleo Athens Greece

The aim of the present study was to assess image quality of PET scanners through a thin layer chromatography (TLC) plane source. The source was simulated using a previously validated Monte Carlo model. The model was developed by using the GATE MC package and reconstructed images obtained with the STIR software for tomographic image reconstruction. The simulated PET scanner was the GE DiscoveryST. A plane source consisted of a TLC plate, was simulated by a layer of silica gel on aluminum (Al) foil substrates, immersed in 18F-FDG bath solution (1MBq). Image quality was assessed in terms of the modulation transfer function (MTF). MTF curves were estimated from transverse reconstructed images of the plane source. Images were reconstructed by the maximum likelihood estimation (MLE)-OSMAPOSL, the ordered subsets separable paraboloidal surrogate (OSSPS), the median root prior (MRP) and OSMAPOSL with quadratic prior, algorithms. OSMAPOSL reconstruction was assessed by using fixed subsets and various iterations, as well as by using various beta (hyper) parameter values. MTF values were found to increase with increasing iterations. MTF also improves by using lower beta values. The simulated PET evaluation method, based on the TLC plane source, can be useful in the resolution assessment of PET scanners.

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A Fully Homomorphic Encryption Scheme with Better Key Size

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China Communications 2014年第9期11卷 82-92页

作者： CHEN Zhigang WANG Jian ZHANG ZengNian SONG Xinxia College of Computer Science and Technology Nanjing University of Aeronautics and Astronautics Nanjing 210016 P.R. China College of Computer and Information Zhejiang Wanli University Zhejiang NingBo 315100 P.R. China Faculty of Electronic and Information Engineering Zhejiang Wanli University Zhejiang NingBo 315100 RR. China. College of Junior. Zhejiang Wanli University Zhejiang Ningbo 31510 P.R.China Information Security Group Royal Holloway University of LondonUK.

Fully homomorphic encryption is faced with two problems now. One is candidate fully homomorphic encryption schemes are few. Another is that the efficiency of fully homomorphic encryption is a big question. In this paper, we propose a fully homomorphic encryption scheme based on LWE, which has better key size. Our main contributions are：（1） According to the binary-LWE recently, we choose secret key from binary set and modify the basic encryption scheme proposed in Linder and Peikert in 2010. We propose a fully homomorphic encryption scheme based on the new basic encryption scheme. We analyze the correctness and give the proof of the security of our scheme. The public key, evaluation keys and tensored ciphertext have better size in our scheme. （2） Estimating parameters for fully homomorphic encryption scheme is an important work. We estimate the concert parameters for our scheme. We compare these parameters between our scheme and Bral2 scheme. Our scheme have public key and private key that smaller by a factor of about logq than in Bral2 scheme. Tensored ciphertext in our scheme is smaller by a factor of about log2q than in Bral2 scheme. Key switching matrix in our scheme is smaller by a factor of about log3q than in Bra12 scheme.

关键词： fully homomorphic encryption public key encryption learning with error concert parameters

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Local Topological Linear Discriminant analysis

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Journal of Information and Computational Science 2013年第18期10卷 5859-5866页

作者： Zhao, Hongwei Feng, Lin Liu, Shenglan Wang, Huibing School of Computer Science and Technology Faculty of Electronic Information and Electrical Engineering Dalian University of Technology Dalian 116024 China School of Innovation Experiment Dalian University of Technology Dalian 116024 China Information and Engineering College Dalian University Dalian 116622 China

Subspace learning has been widely applied to face recognition, data clustering and pattern analysis. It is particularly important to supervised learning methods. To deal with the problem of lacking local features in many supervised dimensionality reduction methods, we propose a new supervised dimensionality reduction method called Local Topological Linear Discriminant Analysis (LTLDA) We apply the local topological structure of within-class to the original LDA method. The experimental results show that our method is more efficient to LDA and Maximum Margin Criterion. © 2013 Binary Information Press.

关键词： Face recognition

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DWDM bidirectional wavelength reuse optical wireless transmission in 2×80 Gbit/s capacity

DWDM bidirectional wavelength reuse optical wireless transmi...

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2013 2nd International Workshop on Optical Wireless Communications, IWOW 2013

作者： Hsu, H.Y. Lu, W.C. Minh, H. Le Ghassemlooy, Z. Yu, Y.L. Liaw, S.K. Department of Electronic and Computer Engineering National Taiwan University of Science and Technology Taipei Taiwan Faculty of Engineering and Environment Northumbria University Newcastle-upon Tyne United Kingdom

ISBN: (纸本)9781479911882

We demonstrate a practical 2×80 Gbit/s dense wavelength division multiplexing (DWDM) bidirectional short-range optical wireless link. The measured power penalty for the bidirectional transmission is less than 0.8 dB compared to the back-to-back link and is only 0.2 dB compared to the unidirectional transmission system. This technology may find potential applications for building-to-building and/or indoor communications. © 2013 IEEE.

关键词： Dense wavelength division multiplexing

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A new switching design to finite-time stabilization of nonlinear systems with applications to neural networks

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Neural networks : the official journal of the International Neural Network Society 2014年 57卷 94-102页

作者： Xiaoyang Liu Daniel W C Ho Wenwu Yu Jinde Cao School of Computer Science & Technology Jiangsu Normal University Xuzhou 221116 China Department of Mathematics City University of Hong Kong Hong Kong. Electronic address: liuxiaoyang1979@***. Department of Mathematics City University of Hong Kong Hong Kong School of Automation Nanjing University of Science & Technology Nanjing 210096 China. Department of Mathematics Southeast University Nanjing 210096 China Faculty of Engineering King Abdulaziz University Jeddah 21589 Saudi Arabia. Department of Mathematics Faculty of Science King Abdulaziz University Jeddah 21589 Saudi Arabia.

This paper is concerned with the optimal finite-time stabilization problem for nonlinear systems. For the given stabilization strength, a new switching protocol is designed to stabilize the system with a fast speed. The obtained protocol covers both continuous control and discontinuous one under the framework of Filippov solutions. Some criteria are discussed in detail on how to choose an optimal protocol such that the finite stabilization time can be shortened. Finally, the main theory results are applied to the general neural networks by one numerical example to illustrate the effectiveness of the proposed design method.

关键词： Finite-time stabilization Neural networks Switching scheme

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Effect of the Concentration on the X-ray Luminescence Efficiency of a Cadmium Selenide/Zinc Sulfide (CdSe/ZnS) Quantum Dot Nanoparticle Solution

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Journal of Physics: Conference Series 2015年第1期637卷

作者： I Valais C Michail D Nikolopoulos C Fountzoula A Bakas P Yannakopoulos G Fountos G Panayiotakis I Kandarakis Radiation Physics Materials Technology and Biomedical Imaging Laboratory Department of Biomedical Engineering Technological Educational Institute of Athens Egaleo 122 10 Athens Greece Department of Computer Electronic Engineering Piraeus University of Applied Sciences (Technological Education Institute of Piraeus) Greece Petrou Ralli & Thivon 250 GR122 44 Aigaleo Athens Greece Department of Medical Laboratories Technological Educational Institute of Athens Egaleo Athens Greece Medical Radiological Technology Faculty of Health and Caring Professions Technological Educational Institute of Athens Athens Greece Department of Medical Physics School of Medicine University of Patras 15310 Rion Greece

In the current study preliminary results on the luminescence efficiency (LE) of toluene dissolved Cadmium Selenide/Zinc Sulfide (CdSe/ZnS, Sigma-Aldrich, Lumidot 694622) quantum dot samples (QDs) after exposure to X-rays of variable radiation flux are shown. The distinctive influence of the weight over volume (w/v) concentration of the samples in LE was investigated. The light emission of the QDs was additionally measured after UV irradiation. The distribution of the emitted light was symmetrical with a maximum at 590 nm. The w/v concentration of the QDs varied between 7.1×10-5 mg/mL to 28.4×10-5 mg/mL. The samples were handled in a cubic 12.5×12.5×45mm3 quartz cuvette. Each sample was excited under X-ray irradiation, in the energy range from 50 to 130 kVp using a BMI General Medical Merate tube with rotating Tungsten anode and inherent filtration equivalent to 2 mm Al. The X-ray LE, induced by the 28.4×10-5 mg/mL QDs found higher, however, the distinction was vague in the highly concentrated samples. The maximum efficiency was obtained at the 90 kVp for QDs with 21.3×10-5 mg/mL w/v concentration. In the high energy range (120-130 kVp) all concentration levels exhibited comparable X-ray induced LE. The luminescence properties of the investigated QDs appear promising for X-ray detection applications.

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Comparision of multi-carrier techniques in seven-level asymmetric cascade multilevel inverter

Comparision of multi-carrier techniques in seven-level asymm...

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2013 4th International Conference on Power engineering, Energy and Electrical Drives, POWERENG 2013

作者： Colak, Ilhami Kabalci, Ersan Keven, Gokhan Faculty of Technology Department of Electric and Electronic Engineering Gazi University Ankara Turkey Faculty of Engineering and Architecture Dep. of Electrical and Electronic Eng. Nevsehir University Nevsehir Turkey Vocational College of Haci Bektaş Veli Dep. of Computer Programming Nevsehir University Nevsehir Turkey

ISBN: (纸本)9781467363921

The multilevel inverters (MLIs) are classified into three topologies such as Diode Clamped, Flying Capacitor and Cascade Multilevel Inverter (CMLI). CMLI topologies include two kind of structure that is named symmetric and asymmetric topologies. Asymmetric Cascade MLI (ACMLI) topologies consist of unequal DC sources. Many modulation techniques have been used in ACMLI topology such as Multi-Carrier PWM (MC-PWM), Space Vector PWM and Selective Harmonic PWM. The MC-PWM technique is achieved by four different types. In this study, MC-PWM techniques which are named Phase Disposition PWM, Phase Opposition Disposition PWM, Alternate Phase Opposition Disposition PWM and Phase Shifted PWM have been compared. It is uncovered that Phase Opposition Disposition PWM technique is more convenient in terms of Total Harmonic Distortion of output voltage and current signals and in terms of the quality of power factor in ACMLI which is performed in this study. © 2013 IEEE.

关键词： Pulse width modulation

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SLA (service level agreement) driven orchestration based new methodology for cloud computing services

SLA (service level agreement) driven orchestration based new...

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2012 International Conference on Future Optical Materials and Circuit Design, FOMCD 2012

作者： Irfan, Muhammad Hong, Zhu Aimaier, Nueraimaiti Zhuguo, Li Collage of Computer Science and Technology Huazhong University of Science and Technology Wuhan China Department of Electrical and Electronic Engineering Faculty of Engineering University Putra Malaysia 43400 UPM Serdang Selangor Malaysia Department of control science and technology Huzhong University of Science and Technology Wuhan China

ISBN: (纸本)9783037856413

Cloud Computing is not a revolution;it's an evolution of computer science and technology emerging by leaps and bounds, in order to merge all computer science tools and technologies. Cloud Computing technology is hottest to do research and explore new horizons of next generations of computer Science. There are number of cloud services providers (Amazon EC2), Rackspace Cloud, Terremark and Google Compute Engine) but still enterprises and common users have a number of concerns over cloud service providers. Still there is lot of weakness, challenges and issues are barrier for cloud service providers in order to provide cloud services according to SLA (Service Level agreement). Especially, service provisioning according to SLAs is core objective of each cloud service provider with maximum performance as per SLA. We have identified those challenges issues, as well as proposed new methodology as "SLA (Service Level Agreement) Driven Orchestration Based New Methodology for Cloud Computing Services". Currently, cloud service providers are using "orchestrations" fully or partially to automate service provisioning but we are trying to integrate and drive orchestration flows from SLAs. It would be new approach to provision cloud service and deliver cloud service as per SLA, satisfying QoS standards. © (2013) Trans Tech Publications, Switzerland.

关键词： Quality of service

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An optimal relaying scheme for delay-tolerant networks with heterogeneous mobile nodes

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IEEE Transactions on Vehicular technology 2013年第5期62卷 2239-2252页

作者： Li, Yong Wang, Zhaocheng Su, Li Jin, Depeng Chen, Sheng Tsinghua National Laboratory for Information Science and Technology Department of Electronic Engineering Tsinghua University Beijing 100084 China Department of Electronics and Computer Science University of Southampton Southampton SO17 1BJ United Kingdom Faculty of Engineering King Abdulaziz University Jeddah 21589 Saudi Arabia

To provide communication services in delay-tolerant networks (DTNs) where there may exist no end-to-end paths between mobile node pairs, a variety of relaying and routing algorithms have been proposed under the assumption that the mobile nodes are homogeneously distributed in the network with the same contact rate and delivery cost. However, experimental data have revealed the heterogeneous contact rates between node pairs, and various applications of DTNs have shown that the mobile nodes often belong to different types in terms of energy consumption, communication ability, and other properties. Following the philosophy of exploiting the heterogeneous features of nodes to enhance the routing performance, we design an optimal relaying scheme for DTNs, which takes into account the nodes' heterogeneous contact rates and delivery costs when selecting relays to minimize the delivery cost while satisfying the required message delivery probability. We use the trace-driven simulations to demonstrate the effectiveness of our optimal relaying scheme in various distributions of nodes' delivery costs and mobility environments. Simulation results show that our proposed optimal relaying scheme requires the least delivery cost and achieves the largest maximum delivery probability, compared with the schemes that neglect or do not fully take into account nodes' heterogeneity. © 1967-2012 IEEE.

关键词： Delay tolerant networks

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