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Measuring quality of experience for 360-degree videos in virtual reality

Science China(Information Sciences) 2020年第10期63卷 108-122页

作者： Muhammad Shahid ANWAR Jing WANG Asad ULLAH Wahab KHAN Sadique AHMAD Zesong FEI School of Information and Electronics Beijing Institute of Technology Faculty of engineering Sciences and Technology Iqra University

In recent years, we witness dramatic growing attention in immersive media technologies like 360-degree videos and virtual reality(VR). However, measuring the quality-of-experience(QoE) for 360-degree VR videos is not a trivial task. Streaming such videos to head mounted displays(HMDs) is extremely bandwidth-demanding when compared to traditional 2D videos. In HTTP adaptive streaming, QoE tends to deteriorate significantly during fluctuating network conditions, which results in various bitrate changes and causes multiple stalling events during playback. Thus, understanding how the human visual system perceives 360-degree video with the effect of stalling and different bitrate levels becomes inevitable. In this paper, we investigate the impact of stalling on users QoE under different bitrate levels and the interaction between stalling event and bitrate level for 360-degree videos in VR. To aim this, we first build a 360-degree videos database by encoding videos in three different bitrate levels(1, 5, and 15 Mbps) with 4 K resolutions(3840×1920 pixels). We then simulate various stalling events in the videos and conduct a subjective experiment in a virtual reality environment to investigate the human responses. Finally, we use a Bayesian method to estimate and predict the QoE while measuring the quality drop owing to various stalling events and bitrate changes. Proposed solution and prediction results show a strong dependency between playback stalling and bitrate of 360-degree video in VR. Stalling always impacts the QoE of 360-degree videos, but the strength of this negative impact depends on the video bitrate level. The adverse effect of stalling events is more profound when bitrate level approaches to the high and low end, which is in close agreement with subjective opinion.

关键词： quality of experience stalling virtual reality 360-degree video

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Signal decomposition of HF radar maneuvering targets by using S^2-method with clutter rejection

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Journal of Systems engineering and Electronics 2012年第2期23卷 167-172页

作者： Yinsheng Wei Shanshan Tan Department of Electronics engineering Harbin Institute of TechnologyHarbin 150001P.R.China

Multiple maneuvedng targets signal processing in high frequency radar is challenging due to the following difficulties： the interference between signals is severe because of significant spread of the target Doppler spectrum, the low signal to clutter ratio （SCR） environment degrades the performance of signal process- ing algorithms. This paper addresses this challenging problem by using an S2-method and an adaptive clutter rejection scheme. The proposed S2-method improves the S-method by eliminating inter- ference between signals, and thus it enables multi-target signals to be reconstructed individually. The proposed adaptive clutter rejec- tion scheme is based on an adaptive notch filter, which is designed according to the envelop of the clutter spectrum. Experiments with simulated targets added into radar sea clutter echo and real air target data illustrate the effectiveness of the proposed method.

关键词： multiple maneuvering target high frequency (HF)radar time-frequency analysis adaptive clutter rejection.

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Amyloid fibril-supported Pd nanoparticles as electrocatalyst for hydrogen peroxide reduction

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Nuclear Science and Techniques 2016年第4期27卷 152-157页

作者： Li-Xia Kong Lan-Jie Wang Lan-Lan Su Zhi-Jie Zhao Zhong-Dan Yan Gong-Jun Zhang Xing-Fei Zhou Faculty of Science Ningbo University Ningbo institute of Material Technology and engineering Chinese Academy of Sciences

Palladium nanoparticles(Pd NPs) were fabricated by using insulin amyloid fibrils(INSAFs) as *** force microscopy measurements showed that ultrasmall Pd NPs were well adsorbed and dispersed on surfaces of INSAFs. X-ray photoelectron spectroscopy confirmed the partial reduction of Pd ion into metallic Pd(0) probably due to the presence of Cys groups on surface of the insulin fibrils. The electrochemical performance of Pd/INSAFs to reduction of H_2O_2 was further evaluated by cyclic voltammetry. The remarkably high electrocatalytic activity, low detection limitation and excellent stability make the Pd/INSAFs a promising bio-nanoelectrocatalyst.

关键词： Pd纳米粒子纤维表面过氧化氢还原催化剂粉样钯纳米粒子 X射线光电子能谱负载

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A fully solid-state cold thermal energy storage device for car seats using shape-memory alloys

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Frontiers in Energy 2023年第4期17卷 504-515页

作者： Yian LU Suxin QIAN Jun SHEN Department of Refrigeration and Cryogenic engineering Xi’an Jiaotong UniversityXi’an710049China Key Laboratory of Cryogenics Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing100190China Department of Energy and Power engineering School of Mechanical EngineeringBeijing Institute of TechnologyBeijing100081China

Thermal energy storage has been a pivotal technology to fill the gap between energy demands and energy *** a solid-solid phase change material,shape-memory alloys(SMAs)have the inherent advantages of leakage free,no encapsulation,negligible volume variation,as well as superior energy storage properties such as high thermal conductivity(compared with ice and paraffin)and volumetric energy density,making them excellent thermal energy storage *** these characteristics,the design of the shape-memory alloy based the cold thermal energy storage system for precooling car seat application is introduced in this paper based on the proposed shape-memory alloy-based cold thermal energy storage *** simulation results show that the minimum temperature of the metal boss under the seat reaches 26.2°C at 9.85 s,which is reduced by 9.8°C,and the energy storage efficiency of the device is 66%.The influence of initial temperature,elastocaloric materials,and the shape-memory alloy geometry scheme on the performance of car seat cold thermal energy storage devices is also *** SMAs are both solid-state refrigerants and thermal energy storage materials,hopefully the proposed concept can promote the development of more promising shape-memory alloy-based cold and hot thermal energy storage devices.

关键词： shape-memory alloy(SMA) elastocaloric effect(eCE) cooled seat cold thermal energy storage

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Design and fabrication of button-style beam position monitors for the HEPS synchrotron light facility

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Nuclear Science and Techniques 2022年第11期33卷 61-78页

作者： Jun He Yan-Feng Sui Yong Li Xu-Hui Tang Lin Wang Fang Liu Zhi Liu Ling-Da Yu Xiao-Yu Liu Tao-Guang Xu Jian-She Cao Jun-Hui Yue Key Laboratory of Particle Acceleration Physics and Technology Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China University of Chinese Academy of Sciences Beijing 100049China

At the high Energy Photon Source (HEPS),a high orbital stability of typically 10% of the beam size and angular divergence must be *** beam size at the insertion devices is 10μm horizontally and 1μm vertically,which implies that the beam orbit must be stabilized to the sub-micrometer *** results in stringent tolerance and quality control requirements for the series production of beam position monitor (BPM) *** this study,analytical formulas were used and CST simulations were performed to analyze the effects of the mechanical tolerances of BPM pickups on beam position *** results of electromagnetic?eld simulations revealed how various mechanical errors,such as button size and location accuracy,as well as the related button capacitance,exert different in?uences on the beam position *** performance of an actual BPM pickup was measured,along with an assessment of the error on the beam position ***,a wake?eld analysis,including an investigation of trapped resonant modes and related thermal deformation,was conducted.

关键词： high energy photon source BPM Error CST Tolerances

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Zr-MOFs loaded on polyurethane foam by polydopamine for enhanced dye adsorption

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Journal of Environmental Sciences 2021年第3期33卷 177-188页

作者： Jingjing Zhao Linqiong Xu Yaozhuo Su Hongwei Yu Hui Liu Shaoping Qian Wenge Zheng Yongqing Zhao School of Materials Science and Chemical engineering Ningbo UniversityNingbo 315211China Ningbo Key Lab of Polymer Materials Ningbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo 315201China School of Materials Science and engineering Wuhan Institute of TechnologyWuhan 430205China

Zirconium-based metal-organic frameworks(Zr-MOFs)have attracted widespread attention due to their high specific surface area,high porosity,abundant metal active sites and excellent hydrothermal ***,Zr-MOFs materials are mostly powdery in nature and thus difficult to separate from aqueous media,which limits their application in wastewater *** this study,PDA/Zr-MOFs/PU foam was constructed by growing Zr-MOFs nanoparticles on a dopamine-modified polyurethane foam substrate by in-situ hydrothermal synthesis as an adsorbent for removing dyes from *** results demonstrated that the polydopamine coating improves the dispersion of the Zr-MOFs nanoparticles on the substrate and enhances the interaction between the Zr-MOFs nanoparticles and the PU foam *** a result,compared with Zr-MOFs/PU foam,the prepared PDA/ZrMOFs/PU foam exhibits higher adsorption capacity for crystal violet(CV)(63.38 mg/g)and rhodamine B(RB)(67.73 mg/g),with maximum adsorption efficiencies of CV and RB of 98.4%(pH=11)and 93.5%(pH=7),respectively,at a concentration of 10 mg/*** PDA/Zr-MOFs/PU foam can simultaneously remove CV and RB from the mixed ***,the PDA/ZrMOFs/PU foam still exhibits high stability and reusability after five cycles.

关键词： Metal-organic framework Polydopamine Polyurethane foam Dye

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Synthesis,characterization,and thermostability of bis(2,2,6,6-tetramethyl-3,5-heptanedionato)copper(Ⅱ)

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Rare Metals 2012年第4期31卷 343-349页

作者： ZHANG Teng,GU Hongwei,DING Fazhu,QU Fei,and DAI Shaotao Key Laboratory of Applied Superconductivity,institute of Electrical engineering,Chinese Academy of Sciences,Beijing 100190,China Key Laboratory of Applied Superconductivity Institute of Electrical Engineering Chinese Academy of Sciences Beijing China

Owing to the adaptability to large scale processing,excellent composition control and film uniformity,the metal-organic chemical vapor deposition（MOCVD） technique is a promising process for high-temperature superconductor YBa;Cu;O;（YBCO） *** this technique,the evaporation characteristics and thermostability of adopted precursors in whole process will decide the quality and reproducible results of YBCO *** the present report,bis（2,2,6,6-tetramethyl-3,5-heptanedionato）copper（II）(Cu（TMHD）;) was synthesized by the interaction of copper acetate hydrate with TMHD in methanol solution,and its structure was identified by FTIR,1 H NMR,and EI-MS ***,thermal property and the kinetics of decomposition were systematically investigated by nonisothermal thermogravimetric analysis methods（TGA） at different heating rates in streams of N;,and the average apparent activation energy of evaporation process was evaluated by the Ozawa,Kissinger,and Friedman *** possible conversion function was estimated through the Coats-Redfern method to characterize the evaporation patterns and followed a phase boundary reaction mechanism by the contracting area equation with average activation energy of 85.1 kJ·mol;.

关键词： Cu(TMHD)_2 metal-organic chemical vapor deposition(MOCVD) synthesis thermostability

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Investigation of the Effect of Pilot Burner on Lean Blow Out Performance of A Staged Injector

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Journal of Thermal Science 2014年第6期23卷 600-608页

作者： YANG Jinhu ZHANG Kaiyu LIU Cunxi RUAN Changlong LIU Fuqiang XU Gang Key Laboratory of Light-duty Gas-turbine Institute of Engineering ThermophysicsChinese Academy of Sciences

The staged injector has exhibited great potential to achieve low emissions and is becoming the preferable choice of many civil airplanes. Moreover, it is promising to employ this injector design in military engine, which requires most of the combustion air enters the combustor through injector to reduce smoke emission. However, lean staged injector is prone to combustion instability and extinction in low load operation, so techniques for broadening its stable operation ranges are crucial for its application in real *** this work, the LBO performance of a staged injector is assessed and analyzed on a single sector test *** experiment was done in atmospheric environment with optical access. Kerosene-PLIF technique was used to visualize the spray distribution and common camera was used to record the flame patterns. Emphasis is put on the influence of pilot burner on LBO performance. The fuel to air ratios at LBO of six injectors with different pilot swirler vane angle were evaluated and the obtained LBO data was converted into data at idle condition. Results show that the increase of pilot swirler vane angle could promote the air assisted atomization, which in turn improves the LBO performance slightly. Flame patterns typical in the process of LBO are analyzed and attempts are made to find out the main factors which govern the extinction process with the assistance of spray distribution and numerical flow field results. It can be learned that the flame patterns are mainly influenced by structure of the flow field just behind the pilot burner when the fuel mass flow rate is high; with the reduction of fuel, atomization quality become more and more important and is the main contributing factor of LBO. In the end of the paper,conclusions are drawn and suggestions are made for the optimization of the present staged injector.

关键词： Staged injector LBO Spray distribution Flame pattern

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Feature-based Image Sequence Compression Coding

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high Technology Letters 2001年第2期7卷 31-33页

作者：周志权 Jia Shilou Department of Electronics and Communications engineering Harbin Institute of Technology

A novel compressing method for video teleconference applications is presented. Semantic-based coding based on human image feature is realized, where human features are adopted as parameters. Model-based coding and the... 详细信息

关键词： Compression coding Model-based Feature-based

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Mutagenesis and selection of high efficiency hydrogen-producing mutants by ultraviolet radiation

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Journal of Harbin institute of Technology(New Series) 2006年第6期13卷 635-639页

作者：任南琪郑国香李永峰林海龙李建政 School of Municipal and Environmental engineering Harbin Institute of Technology

Hydrogen is an ideal, clean and sustainable energy source for the future because of its high conversion and nonpolluting nature. Biohydrogen production by dark-fermentation appears to have a great potential to be developed for practical application. However, one limiting factor affecting the development of hydrogen-production industrialization is that the hydrogen-producing capacity of bacteria is lower, so how to increase bacteria＇ s hydrogen-producing ability will be an urgent issue. In this experiment, 2 mutants, namely UV3 and UV7, were obtained by ultra-violet radiation. They grew and produced hydrogen efficiently on iron-containing medium. The hydrogen evolution of UV3 and UV7 were 2 356. 68 ml/L and 2 219. 62 ml/L at a glucose concentration of 10 g/L, respectively. With wild parent strain Ethanoligenens sp. ZGX4, the hydrogen evolution was 1 806. 02 ml/L under the same conditions. Mutants＇ hydrogen-producing capacities were about 29. 71% and 22.22% higher than that of wild parent strain ZGX4. The maximum H2 production rate by mutants UV3 and UV7 were estimated to be 32.57 mmol H2/g cell h and 31.19 mmol H2/g cell h, respectively, which were 38. 18% and 34. 78% higher than the control （23.57 mmol H：/g cell h）. The abundant products of UV3 and UV7 were ethanol and acetic, which accounted for 95% - 98% of total soluble microbial products. In each case, mutant strains UV3 and UV7 evolved hydrogen at a higher rate than the wild type, showing a possible potential for commercial hydrogen production. Another mutant named UV20＇ was also gained whose main end metabolites were butyric acid and acetic acid. This would provide researched material for a discussion of metabolic pathways of hydrogen-producing bacteria.

关键词： biohydrogen UV-mutagenesis mutants

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