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Development of a compact DOI-TOF detector module for high-performance PET systems

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Nuclear Science and Techniques 2017年第4期28卷 1-7页

作者： Qing-Yang Wei tian-Peng Xu tian-tian Dai Shi Wang Ya-Qiang Liu yu Gu tian-yu Ma School of Automatic and Electrical Engineering University of Science and Technology Beijing Beijing 100083 China Department of Engineering Physics Tsinghua UniversityBeijing 100084 China Key Laboratory of Particle and Radiation Imaging (Tsinghua University) Ministry of Education Beijing 100084 China Department of Radiation Oncology China-Japan Friendship Hospital Beijing 100029 China

To increase spatial resolution and signal-to-noise ratio in PET imaging,we present in this paper the design and performance evaluation of a PET detector module combining both depth-of-interaction(DOI) and time-offlight(TOF) *** detector module consists of a staggered dual-layer LYSO block with2 mm × 2 mm × 7 mm ***-compatible SiPM sensors(MicroFJ-30035-TSV,SensL) are assembled into an 8× 8 *** signals from both fast and slow outputs are read out by a 128-channel ASIC *** test its performance,a flood histogram is acquired with a ^(22)Na point source on top of the detector,and the energy resolution and the coincidence resolving time(CRT) value for each individual crystal are *** flood histogram shows excellent crystal separation in both *** average energy resolution at 511 keV is 14.0 and 12.7%at the bottom and top layers,*** average CRT of a single crystal is 635 and 565 ps at the bottom and top layers,*** conclusion,the compact DOI-TOF PET detector module is of excellent crystal identification capability,good energy resolution and reasonable time resolution and has promising application prospective in clinical TOF PET,PET/MRI,and brain PET systems.

关键词： Positron emission tomography SiPM Depth of interaction (DOI) Time-of-flight (TOF)

Prediction of ball-on-plate friction and wear by ANN with data-driven optimization

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Friction 2024年第6期12卷 1235-1249页

作者： Alexander KOVALEV yu tian Yonggang MENG State Key Laboratory of Tribology in Advanced Equipment Tsinghua UniversityBeijing 100084China

For training artificial neural network(ANN),big data either generated by machine or measured from experiments are used as input to"learn"the unspecified functions defining the *** experimental data are fed directly into the optimizer allowing training to be performed according to a predefined loss *** predict sliding friction and wear at mixed lubrication conditions,in this study a specific ANN structure was so designed that deep learning algorithms and data-driven optimization models can be *** ball-on-plate friction and wear data were analyzed using the specific training procedure to optimize the weights and biases incorporated into the neural layers of the ANN,and only two independent experimental data sets were used during the ANN optimization *** the training procedure,the ANN is capable to predict the contact and hydrodynamic pressure by adapting the output data according to the tribological condition implemented in the optimization algorithm.

关键词： machine learning deep learning artificial neural network mixed lubrication

Attitude Tracking Control for Rigid Spacecraft with Arbitrary Convergence Time

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Journal of Systems Science & Complexity 2024年第6期37卷 2579-2594页

作者： XU yu-tian WU Ai-Guo Guangdong Provincial Key Laboratory of Intelligent Morphing Mechanisms and Adaptive Robotics Harbin Institute of Technology(Shenzhen)Shenzhen 518055China Key University Laboratory of Mechanism&Machine Theory and Intelligent Unmanned Systems of Guangdong Harbin Institute of Technology(Shenzhen)Shenzhen 518055China Department of Automation Harbin Institute of Technology(Shenzhen)Shenzhen 518055China HIT Wuhu Robot Technology Research Institute Wuhu 241060China

In this paper,attitude tracking control with arbitrary convergence time for rigid spacecraft is ***,a novel time-varying sliding function is proposed to achieve free-will arbitrary time convergence when the system states reside on the sliding *** such a sliding function,an attitude tracking controller is designed to guarantee that the states of the closed-loop system converge to the sliding surface within a predetermined time in the presence of external *** free-will arbitrary time convergences of the closed-loop system and sliding function are illustrated by numerical simulations.

关键词： Attitude tracking free-will arbitrary time stability rigid spacecraft sliding mode control

Subspace dual super wavelet and Gabor frames

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Science China Mathematics 2017年第12期60卷 2429-2446页

作者： tian yu LI yunZhang College of Applied Sciences Beijing University of Technology Beijing 100124 China

Due to its potential applications in multiplexing techniques, the study of superframes has interested some researchers. This paper addresses dual super wavelet and Gabor frames in the subspace setting. We obtain a basic-equation characterization for subspace dual super wavelet and Gabor frames. In addition, applying this characterization, we derive a procedure that allows for constructing subspace dual super wavelet frames based on certain subspace dual super Gabor frames, and vice versa. Our results are new even in L^2(R, CL) setting.

关键词： frame superframe dual super wavelet frame dual super Gabor frame

Non-spherical particle mixing behaviors by spherical inert particles assisted in a fluidized bed

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Petroleum Science 2020年第2期17卷 509-524页

作者： An-Xing Ren tian-yu Wang tian-Qi Tang yu-Rong He School of Energy Science and Engineering Harbin Institute of TechnologyHarbin 150001China Heilongjiang Key Laboratory of New Energy Storage Materials and Processes School of Energy Science and EngineeringHarbin Institute of TechnologyHarbin 150001China

Fluidized beds are widely used in many industrial fields such as petroleum,chemical and *** actual industrial processes,spherical inert particles are typically added to the fluidized bed to promote fluidization of non-spherical *** mixing behaviors of binary mixtures in a fluidized bed has specific significance for the design and optimization of related industrial *** this study,the computational fluid dynamic-discrete element method with the consideration of rolling friction was applied to evaluate the mixing behaviors of binary mixtures comprising spherocylindrical particles and spherical particles in a fluidized *** simulation results indicate that the differences between rotational particle velocities were higher than those of translational particle velocities for spherical and non-spherical particles when well ***,as the volume fraction of the spherocylindrical particles increases,translational and rotational granular temperatures gradually *** addition,the addition of the spherical particles makes the spherocylindrical particles preferably distributed in a vertical orientation.

关键词： Non-spherical particle Fluidized bed Discrete element method Binary mixtures

Doubled conformal compactification

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Science China(Physics,Mechanics & Astronomy) 2014年第9期57卷 1630-1636页

作者： SUN ZhaoYong tian yu School of Physics University of Chinese Academy of Sciences State Key Laboratory of Theoretical Physics Institute of Theoretical Physics Chinese Academy of Sciences

We use Weyl transformations between the Minkowski spacetime and dS/AdS spacetime to show that one cannot well define the electrodynamics globally on the ordinary conformal compactification of the Minkowski spacetime(or dS/AdS spacetime),where the electromagnetic field has a sign factor(and thus is discountinuous)at the light *** problem is intuitively and clearly shown by the Penrose diagrams,from which one may find the remedy without too much *** use the Minkowski and dS spacetimes together to cover the compactified space,which in fact leads to the doubled conformal *** this doubled conformal compactification,we obtain the globally well-defined electrodynamics.

关键词： conformal transformations electrodynamics doubled Penrose diagrams conformal compactification

Quantum Private Comparison via Cavity QED

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Communications in Theoretical Physics 2017年第2期67卷 147-156页

作者： tian-yu Ye College of Information and Electronic Engineering Zhejiang Gongshang University Hangzhou 310018 China

The first quantum private comparison(QPC) protocol via cavity quantum electrodynamics(QED) is proposed in this paper by making full use of the evolution law of atom via cavity QED, where the third party(TP) is allowed to misbehave on his own but cannot conspire with either of the two users. The proposed protocol adopts two-atom product states rather than entangled states as the initial quantum resource, and only needs single-atom measurements for two users. Both the unitary operations and the quantum entanglement swapping operation are not necessary for the proposed protocol. The proposed protocol can compare the equality of one bit from each user in each round comparison with one two-atom product state. The proposed protocol can resist both the outside attack and the participant ***, it can prevent TP from knowing two users' secrets. Furthermore, the qubit efficiency of the proposed protocol is as high as 50%.

关键词： quantum private comparison(QPC) third party(TP) cavity quantum electrodynamics(QED) product state participant attack

The Analysis of Impact of Brexit on the Post-Brexit EU Using Intervented Multivariate Time Series

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Acta Mathematicae Applicatae Sinica 2021年第3期37卷 441-458页

作者： yu tian Shao-pei MA Rong-xiang RUI Zhen yu Mao-zai tian Institute for Diplomacy and International Governance Loughborough University LondonE203BSUK Center for Applied Statistics School of StatisticsRenmin University of ChinaBeijing 100872China College of Medical Engineering and Technology Xinjiang Medical UniversityUrumqi 830011China School of Statistics and Data Science Xinjiang University of Finance and EconomicsUrumqi 830012China School of Statistics Lanzhou University of Finance and EconomicsLanzhou 730101China

The UK is the most important partner of the EU in terms of economic and other fields due to the geographical *** was one of the largest economies in the EU and its per capita income is higher than the EU average,so it is a net contributor to the *** UKs membership of the EU ended on 31 January 2019,there are concerns that the Brexit may have a significant impact on the EU,resulting in social,economic,political,and institutional changes,*** *** the impact of Brexit on the UK has always been the subject of considerable scholarly interest in recent years,there is relatively little literature on the impact of Brexit on the *** paper focuses on the evaluation of the impact of Brexit on the EU economy and other relevant aspects along three dimensions:GDP,PPP,Quarterly GDP *** powerful quantitative analysis technology that includes vector autoregression model,multivariate time series model with intervention variables,and autoregression integrated moving average,this paper obtains the important and novel evidence about the potential impact of Brexit on the EU economy,pointing out that Brexit is of far-reaching significance to the *** analysis uses several statistical models to screen out several key influencing factors,which can be used to predict the total GDP of EU in the next five *** results show that EU economy will react negatively to"no-deal"Brexit,and its growth rate of economy will slow down significantly in next 5 ***,we put forward relevant policy suggestions on how to deal with the negative impact of Brexit on EU.

关键词： intervention multivariate time series model Brexit economy gaping Brexit hole no-deal Brexit post-Brexit EU

In memoriam:Shizhu Wen(1932-2023)

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Friction 2024年第7期12卷 1341-1346页

作者： Jianbin LUO Yonggang MENG yu tian State Key Laboratory of Tribology in Advanced Equipment Tsinghua UniversityBeijing 100084China

Professor Shizhu Wen,the winner of the 2015 Tribology Gold Medal,passed away due to illness on November 3,2023,at the age of *** was a professor of Tsinghua University,an academician of the Chinese Academy of Sciences,and the Honorary President of the Chinese Tribology Institute(CTI)from 1997 to *** Wen was born in 1932 in Jiangxi Province of China and graduated from Tsinghua University in 1955,where he was awarded the Outstanding Graduate Gold Medal and then remained as an assistant professor at the *** Wen was promoted to full professor in *** had undertaken tribology research at the Imperial College London in 1979 and *** 1985,he presided over the establishment of the State Key Laboratory of Tribology(SKLT)of Tsinghua University and served as the first director of the SKLT.

关键词： sided professor zhu