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Joint video adaptation and erasure code for video broadcast in wireless networks

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Science China(Information Sciences) 2013年第10期56卷 102-116页

作者： HE NengQiang ZHANG Xuedan LI YiPeng CAO JianNong LI Zhu ren Yong department of Electronic Engineering Tsinghua University department of Automation Tsinghua University department of Computing Hong Kong Polytechnic University

Advances in wireless access technologies such as WiMax and LTE have accelerated the development of wireless video *** existing erasure codes are designed for wireless data broadcasting,their potential can only be realized for wireless video broadcasting if the distortions associated with video packets and their complex decoding dependency are taken into *** this paper,we propose the greedy video erasure code(GVEC)to minimize average video distortion by accounting for the temporal scalable decoding dependency among video frames e.g.I,P and B frames in *** is a greedy algorithm and sufers from high computational *** practical implementation,we have designed the joint video adaptation and erasure code(JVEC)with lower complexity,which can generate erasure codes on the fly to guarantee the decoding of important video *** results show that the performance of JVEC is very close to that of GVEC,and is superior to that of existing erasure *** results also show the existence of a performance tradeof between video distortion and video packet throughput.

关键词： wireless video broadcast erasure code video analysis

Maneuvering charge polarization and transport in 2HMoS2 for enhanced electrocatalytic hydrogen evolution reaction

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Nano Research 2016年第9期9卷 2662-2671页

作者： Wei Ye Chenhao ren daobin Liu Chengming Wang Ning Zhang Wensheng Yan Li Song Hefei National Laboratory for Physical Sciences at the Microscale iChEM(Collaborative Innovation Center of Chemistry for Energy Materials)Hefei Science Center(CAS)School of Chemistry and Materials Scienceand National Synchrotron Radiation LaboratoryUniversity of Science and Technology of ChinaHefei 230026China

Semiconducting 2H-MoS2with high chemical stability is a promising alternative to the existing electrocatalysts for the hydrogen evolution reaction (HER); however, the HER performance largely suffers from the limited number of active S sites and low mobility for charge transport. In this work, we demonstrate that the limitations of 2H-MoS2for the HER can be overcome by forming hybrid structures with metallic nanowires. Taking the integration with Pd as a proofof- concept, we show with solid experimental evidence that the one-dimensional structure of metallic nanowires facilitates electron transport to active S sites, while the interfacial charge polarization between MoS2and Pd increases the electron density of the S sites for improved activity. As a result, the hybrid structure exhibits a current density of 122 mA·cm-2at -300 mV versus RHE and a Tafel slope of 44 mV·decade-1with excellent durability, well exceeding the performances of bare 2H-MoS2and metallic 1T-MoS2. This work provides insights into electrocatalyst design based on charge transport and polarization, which can be extended to other hybrid structures. [Figure not available: see fulltext.] © 2016, Tsinghua University Press and Springer-Verlag Berlin Heidelberg.

关键词： hydrogen evolution molybdenum disulfide charge transport charge polarization nanowire

Synthesis and Purple-Blue Emission of Antimony Trioxide Single-Crystalline Nanobelts with Elliptical Cross Section

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Nano Research 2009年第2期2卷 151-160页

作者： Zhengtao deng dong Chen Fangqiong Tang Jun ren Anthony J.Muscat Laboratory of Controllable Preparation and Application of Nanomaterials Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100080China department of Chemical and Environmental Engineering The University of ArizonaTucsonArizona 85721USA College of Optical Science The University of ArizonaTucsonArizona 85721USA

Single-crystalline orthorhombic antimony trioxide(Sb_(2)O_(3))nanobelts with unique elliptical cross sections and purple-blue photoluminescence have been *** uniform Sb2O3 nanobelts are 400600 nm in width,2040 nm in thickness at the center and gradually become thinner to form sharp edges sub-5 nm in size,tens of micrometers in length,and with[001]as the preferential growth ***-assembly of tens of nanobelts into three-dimensional(3-d)flower-like nanostructures has been *** was performed by X-ray diffraction,energy-dispersive X-ray spectroscopy,X-ray photoelectron spectroscopy,scanning electron microscopy,high-resolution transmission electron microscopy,selected area electron diffraction,Raman spectroscopy,Fourier transform infrared spectroscopy,and photoluminescence *** Sb_(2)O_(3) nanobelts display intense purple-blue photoluminescence centred at 425 nm(~2.92 eV).The successful synthesis of nanobelts with elliptical cross sections may cast new light on the investigation of the property differences between nanobelts with rectangular cross sections and those with other cross section *** Sb2O3 nanobelts can be used as effective purple-blue light emitters and may also be valuable for future nanodevice design.

关键词： Antimony trioxide nanobelts elliptical cross section purple-blue photoluminescence

Experimental Investigation of Multi-Mode Vortex-Induced Vibration of Flexible Risers with different Mass Ratios

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China Ocean Engineering 2023年第1期37卷 1-15页

作者： WANG Yu LOU Min ren Xiao-hui LIANG Wei-xing LI Xiang dANG Peng-bo School of Petroleum Engineering China University of Petroleum(East China)Qingdao 266580China Key Laboratory of Unconventional Oil&Gas development(China University of Petroleum(East China)) Ministry of EducationQingdao 266580China College of Civil Engineering and Architecture Shandong University of Science and TechnologyQingdao 266590China

Experiments were conducted on risers with different mass ratios to study the effect of mode conversion and spanwise correlation. The slenderness ratio of the riser model was set as 169, and the Reynolds numbers are 1600-14400. The dynamic responses of riser models versus reduced velocity were analyzed, and the spanwise displacement, frequency,and trajectory of the mode conversion from the lower to the higher mode were explored. The results revealed that the riser model with a higher mass ratio excites a higher number of modes. The conversion region of multi-mode competition exists and narrows with the increasing mass ratio. Mode conversion is continuous and manifests as the transmission of peaks and troughs in mode shape: the peaks and troughs of mode shape move up in the mode stable development region and move down in the mode conversion region. The single-mode dominating vibration exhibits a standing wave feature, and the traveling wave feature is significant in the mode conversion region. Furthermore, the frequency jump is always transmitted from the trough to the peak of the mode shape, and finally, all the axial positions vibrate at the same frequency. The trajectory in the mode conversion region deviates from the 8-shape and recovers the standard8-shape at the middle and late stages of the mode stable development region.

关键词： vortex-induced vibration dynamic response mode conversion mass ratio mode weight

Effect of seepage on soil arching effect in deep shield tunnel

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Underground Space 2023年第5期12卷 218-233页

作者： Xu Song Fan-Yan Meng ren-Peng Chen Han-Lin Wang Huai-Na Wu Research Center for Advanced Underground Space Technologies of Hunan University Changsha 410082China Key Laboratory of Building Safety and Energy Efficiency of the Ministry of Education Hunan UniversityChangsha 410082China College of Civil Engineering Hunan UniversityChangsha 410082China

Shield tunneling and post-tunneling steady seepage are accompanied by stress and displacement variations,which could induce and influence the soil arching *** there are many studies on the tunneling-induced soil arching effect,the research about the effect of seepage on soil arching effect is extremely *** this study,a numerical model is firstly established and verified by field ***,a series of numerical models,whose simulation method of steady seepage is verified by adopting the conformal mapping technique,are established to study the soil arching evolution of deep-buried tunneling and post-construction steady *** results indicate that seepage leads to an increase in effective vertical stress,which is consistent with the existing *** seepage weakens the soil arching effect resulting in the height of the arch zone reducing from 2.38d(d is the tunnel diameter)to *** seepage leads to the further development of ground consolidation settlement,but the differential displacement in the soil mass *** ground reaction curve in the steady seepage condition shows a bigger value than that after *** is reasonable to control the ground loss ratio in the range of 0.5–1.0%,which can minimize overburden pressure with moderate ground deformation.

关键词： Soil arching effect Steady seepage Numerical simulation deep shield tunnel Stress change

Giant Stress-Impedance Effect in Co_(71.8)Fe_( 4.9)Nb_(0.8)Si_(7.5)B_(15) Glass-Covered Amorphous Wires

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Journal of Iron and Steel Research International 2006年第4期13卷 49-50,74页

作者： CHEN Zheng LI de-ren LU Zhi-chao ZHOU Shao-xiong Nanomaterials Engineering and Research Center Central Iron and Steel Research Institute Beijing 100081 China Research and development Center Advanced Technology and Materials Co Ltd Beijing 100081 China

The giant stress-impedance （GSI） effect in as-cast and dC current annealed Co71.8Fe4.9 Nb0.8Si7.5 B15 amorphous glass-covered wires is presented. The SI ratio of the as-cast sample exhibits negative GSI effect. For the sample annealed by 60 mA dC current, the SI ratio first increases with applied tensile stress, then decreases. The maximum ΔZ/Z ratio of 304% is obtained. Frequency dependence in the range from 1 to 110 MHz of the GSI effect is investigated. Experimental results show that the real part R and the imaginary part X of impedance play an important role at high frequency and low frequency, respectively. At 1 MHz, the maximum AX/X ratio of 1448% is obtained. At 110 MHz, the maximum AR/R ratio of 648% is obtained.

关键词： giant stress-impedance amorphous wire dC annealing

Influence of Frequency and Bias Current on Asymmetrical GMI Effect in Co_(71.8)Fe_(4.9)Nb_(0.8)Si_(7.5)B_(15) Amorphous Glass-Covered Wires

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Journal of Iron and Steel Research International 2008年第2期15卷 91-94页

The Co71.8Fe4.9Nb0.8Si7.5B15 amorphous glass-covered wires（AGCW）are prepared by the Taylor-Ulitovsky *** frequency dependence of asymmetrical giant magneto-impedance（AGMI）effect in amorphous glass-covered wires annealed by 70 mA dC current is here *** resistance R and the reactance X have been measured,*** real part R and the imaginary part X of impedance play an important role at high frequency and low frequency,*** influence of dC bias current from Ib=0 mA to Ib=5 mA at 30 MHz on the GMI effect in the glass-covered wires annealed by 70 mA dC current is *** asymmetry becomes the largest around Ib=1 mA,and finally decreases for the larger bias current Ib=5 *** maximum ΔZ/Z ratio of 310% is observed at 58 MHz under 1 mA bias current.

关键词： giant magneto-impedance amorphous wire bias current

Influence of Erosion Induced by NaCl on the Mechanical Performances of Alkali-Activated Mineral Admixtures

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Fluid dynamics & Materials Processing 2023年第9期19卷 2385-2398页

作者： Jing Yu Jie ren Guangming Shen Weixiang Sun Hui Wang department of Architectural Engineering Ningbo PolytechnicNingbo315000China Technology and Performance Management department China Construction Infrastructure Corp.Ltd.Beijing10029China Chief Engineer’s Office Jiuzhou Engineering Design Co.Ltd.Zhengzhou451162China School of Civil Engineering and Geographic Environment Ningbo UniversityNingbo315000China

In this paper,the inﬂuence of NaCl freeze-thaw(F-T)cycles and dry-wet(d-W)alternations on theﬂexural,com-pressive and bonding strengths of alkali-activatedﬂy ash(FA)and a blast furnace slag powder(BFS)is *** considered NaCl concentration is 3%.The effect of polypropyleneﬁbers on the mechanical strengths is also *** electron microscopy(SEM),thermogravimetry(TG)and X-ray diffraction(XRd)are selected to discern the mechanisms underpinning the NaCl-induced *** obtained results indicate that the best results in terms of material resistance are obtained with admixtures containing 60%BFS and 40%FA in terms of mass ratio and 3%polypropyleneﬁbers in terms of volume *** maximum rates of decrease of theﬂexural,compressive and bonding strengths after 300 NaCl F-T cycles are 21.5%,20.3%and 22.6%,*** corresponding rates of decrease due to NaCl d-W alternations are 28.1%,26.1%and 31.5%,*** TG curves show that the alkali-activating activity of BFS is higher than that of ***,in theﬁrst case,the microstructure of the hydration products is more *** results also show that NaCl F-T cycles lead to increasing cracks in the alkali-activated BFS.

关键词： Mechanical performances alkali-activated NaCl dry-wet alternations NaCl freeze-thaw cycles microstructure

10 kV nanosecond pulse generator with high voltage gain and reduced switches

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High Voltage 2024年第5期9卷 1059-1067页

作者： Jiuxin Ma Liang Yu Chenguo Yao Shoulong dong Chengxiang Li Lvheng ren Shixin Wang National Key Laboratory of Power Transmission and Transformation Equipment Technology School of Electrical EngineeringChongqing UniversityChongqingChina

In the article,a new type boost high-voltage nanosecond pulse generator is *** distributed inductance of the transmission line is utilised as the energy storage unit and cooperated with the variable impedance transmission line transformer to generate nanosecond pulses with extremely high-voltage ***’s more,the isolation effect caused by the transmission line time delay is applied to achieve modular *** demand for charging power supply can be greatly reduced,and few switches are ***,the topological principle is verified by experiments,and a prototype of the fivestage stacking prototype is *** the charging voltage of 28 V,the generator can output pulse with a voltage amplitude of 10 kV and pulse width of 12 ns whose voltage gain is up to 357 times.

关键词： pulse generator charging