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International Conference on Signal Processing Proceedings (ICSP)

作者： Xiaoping Zhou Yong Fang Min Wang School of Communication and Information Engineering Key Laboratory of Specialty Fiber Optics and Optical Access Network Shanghai University Shanghai China Key Laboratory of Advanced Display and System Applications Ministry of Education Shanghai China

To improve the performance of time-varying distributed multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems, a subblock-wise channel estimation scheme based on discrete prolate spheroidal basis expansion model (DPS-BEM) is proposed. The time-varying channel is well captured by the DPS-BEM, exploiting the unknown channel slepian correlation. The time-variations of the subblock DPS-BEM coefficients are likely much slower than that of the channel. Thus, the DPS-BEM is more convenient to track in time-varying environments. The DPS-BEM coefficients are estimated via subblock-wise, based on time-multiplexed periodically transmitted training symbols. Simulation results show that the proposed algorithm can effectively improve the channel estimation performance.

关键词： Channel estimation OFDM Transmitting antennas Receiving antennas MIMO Antenna arrays Fading

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Nanofiber based composites for thermal management

Nanofiber based composites for thermal management

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International Microsystems, Packaging, Assembly and Circuits Technology (IMPACT)

作者： Johan Liu Bjorn Carlberg Department of Microtechnology and Nanoscience (MC2) Chalmers University of Technology Goteborg Sweden Key Laboratory of Advanced Display and System Applications & SMIT Center Shanghai University Shanghai China

Since the invention of the integrated circuit increasing transistor integration density has been the main path to increased performance of microelectronic devices. With traditional transistor scaling approaching fundamental limitations, the field of electronic packaging has seen increasing effort towards increased integration density, e.g. three-dimensional packaging. Overall, this has led to tremendous power densities in the order of 100 W/cm 2 . Consequently, thermal management of electronic packages has attracted increasing research interest and has been identified as a research priority by industry consortia iNEMI and ITRS. There is a wide consensus within the microelectronics industry that current thermal interface materials constitute a bottleneck hindering a reduction of junction to ambient thermal resistances to future required levels (2/W. The thermal conductivity is found to be 28 W/mK, approximately 1/3 of the inherent thermal conductivity of the indium metal phase (83.7 W/mK). This clearly indicates the potential of the material in thermal management applications.

关键词： Thermal conductivity Conductivity Metals Polyimides Thermal management

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Channel Properties of indoor part for high-speed train based on wideband channel measurement

Channel Properties of indoor part for high-speed train based...

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International Conference on Communications and Networking in China (CHINACOM)

作者： Weihui Dong Guangyi Liu Li Yu Haiyu Ding Jianhua Zhang China Mobile Research Institute China Mobile Research Institute China Key Laboratory of Advanced Display and System Applications Ministry of Education Shanghai University China Key Laboratory of Universal Wireless Communication Ministry of Education

In this paper, the statistical channel properties and channel modeling of indoor part for high-speed train communication system is presented based on wideband channel measurement at 2.35 GHz. Two configurations of base station (BS) antennas, the omni-directional ceiling antenna and the planar antenna on the wall, are used in the measurement, in order to compare different channel characteristics and facilitate the future wideband system deployment. Channel properties, such as Path Loss (PL), Delay Spread (DS) and Ricean K-factor, are analyzed and modeled. The empirical log-distance PL models are derived. It is found that PL with planar antenna at BS is 10 dB bigger than that with omni-directional antenna. The latter is even smaller than the PL of the free space. The distributions of DS under these two configurations are both well fitted with the lognormal distribution, and the mean values of them are similar. However, K-factors in decibel are quite different, although both follow well with the normal distribution. The mean values of K-factor with the omni-directional antenna and the planar antenna at BS are 10.41 dB and 4.09 dB, respectively.

关键词： Antenna measurements Antennas

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MDS study on the adhesive heat transfer in micro-channel cooler

MDS study on the adhesive heat transfer in micro-channel coo...

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2010 11th International Conference on Electronic Packaging Technology & High Density Packaging(2010 电子封装技术与高密度封装国际会议)

作者： Shun Wang Yan Zhang Zhili Hu Johan Liu Key Laboratory of Advanced Display and System Applications Ministry of Education & SMIT Center School of Mechatronics Engineering and Automation Shanghai University P.O.B. 282 Shanghai 200072 China

Carbon nanotube (CNT) can be used in micro-channel cooler construction due to its excellent thermal conductivity. When fabricating CNTs directly onto the chip, the chip could be damaged because of the high temperature required for CNT growth (about 750℃). As a solution, a transfer technique is developed where the desired carbon nanotube pattern can be obtained by taking off a pre-fabricated CNT forest with a designed adhesive, and the transfer process could make the chip or other components immune from the high temperature required for the CNT growth process. This process can also improve the bonding/adhesive strength. Nevertheless, the use of adhesive in the CNT-based microchannel structure might affect the thermal conduction of the cooling system. In particular, the heat transfer between the heat generator and the CNT fin in the micro-channel cooler shall be evaluated. In this paper the thermal conductivity of the adhesive is studied by molecular dynamics simulation (MDS). The adhesive considered in the present MDS model consists of the epoxy and the curing agent. After the curing process, the epoxy molecules construct a network, which is established in the epoxy matrix generation before the simulation. Nonequilibrium Molecular Dynamics Method (NEMD) is adopted in the modeling and periodic boundary conditions are applied. Furthermore, the heat transfer through CNT and adhesive interface is simulated in this work based on the adhesive results, which can provide information for future macro-analysis of the thermal performance of the CNT microchannel cooler.

关键词： Carbon nanotubes Polymers Thermal resistance Heat transfer Curing

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A Highly Conductive Bimodal Isotropic Conductive Adhesive and Its Reliability

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ECS Transactions 2011年第1期34卷

作者： Dongsheng Li Huiwang Cui Si Chen Qiong Fan Zhichao Yuan Lilei Ye Johan Liu Key Laboratory of Advanced Display and System Applications Ministry of Education and SMIT Center Shanghai University No.149 Yanchang Road Shanghai Shanghai 200072 China Ministry of Education and SMIT Center Shanghai University Shang Da Rui Hu Microsystem Integration Technology Co.Ltd Shanghai University SHT Smart High Tech AB Shanghai University SE-412 96 Gothenburg Gothenburg 41296 Sweden

In this paper, micro silver flakes and micro spherical particles were incorporated into the matrix resin of isotropic conductive adhesives (ICAs). Their electrical properties were investigated. The total weight ratio of silver fillers was kept at 75 wt% for all samples. When the content of micro spherical particles was 8 wt%, the bulk resistivity of the bimodal ICAs reduced dramatically to as low as 1.26×10-4 Ω•cm and its viscosity was 24,289 cP under 5rpm at 25°. Scanning electronic microscopy (SEM) images of the bimodal ICAs showed silver fillers well distributed in the matrix resin. In addition, the lap shear strength of different metal surfaces, and the bulk resistivity shifts during aging time under85°/85% RH for more than 500 hours were also measured. The results showed that bulk resistivity shifts of bimodal ICAs remained stable after further cured and the bond strength on the copper surface was the greatest among the three metal surfaces tested.

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Estimation of electron mobility of n-doped 4,7-diphenyl-1,10-phenanthroline using space-charge-limited currents

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Journal of Semiconductors 2009年第11期30卷 63-66页

作者：希扎尔.乌尔.哈克鲁富翰蒋雪茵张志林张小文张良李俊 School of Materials Science and Engineering Shanghai University Key Laboratories of Advanced Display and System Applications Ministry of EducationShanghai University

The electron mobilities of 4, 7-diphenyl-1, 10-phenanthroline （BPhen） doped 8-hydroxyquinolinatolithium （Liq） at various thicknesses （50-300 nm） have been estimated by using space-charge-limited current measurements. It is observed that the electron mobility of 33 wt% Liq doped BPhen approaches its true value when the thickness is more than 200 rim. The electron mobility of 33 wt% Liq doped BPhen at 300 nm is found to be -5.2 × 10^-3 cm^2/（V.s）（at 0.3 MV/cm） with weak dependence on electric field, which is about one order of magnitude higher than that of pristine BPhen （3.4 × 10^-4 cm^2/（V.s）） measured by SCLC. For the typical thickness of organic light-emitting devices, the electron mobility of doped BPhen is also investigated.

关键词： doping electron mobility SCLC 8-hydroxyquinolinonate-lithium （Liq）

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3D computational fluid dynamics simulation of carbon nanotube based microchannel on-chip cooler

3D computational fluid dynamics simulation of carbon nanotub...

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IMAPS Nordic Annual Conference 2010

作者： Nabiollahi, Nabi Fu, Yifeng Liu, Johan Bionano Systems Laboratory Department of Microtechnology MC2 Chalmers University of Technology Göteborg Sweden FOAB Elektronik Hisings Backa Sweden Key Laboratory of Advanced Display and System Applications Ministry of Education School of Mechatronics Engineering and Automation Shanghai University Shanghai China SHT Smart High-Tech AB Kemivägen 9 412 58 Göteborg Sweden

ISBN: (纸本)9781617821905

Cooling of microsystem electronic device is of great importance, according to increased heat dissipation based on Moore's law. Different solutions are proposed to overcome this issue. On-chip microchannel cooler implements micro-fabrication techniques to achieve large areas in small volume size by introducing micro channel CNT fins with smaller fin pitch. In this paper, a 3D model of this structure is simulated using computational fluid dynamics (CFD) in ANSYS® software, and effect of various parameters such as channel width and height is discussed to achieve an optimized cooling for this system.

关键词： Carbon nanotubes

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Reduced resolution depth compression for multiview video plus depth coding

Reduced resolution depth compression for multiview video plu...

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International Conference on Signal Processing Proceedings (ICSP)

作者： Qiuwen Zhang Ping An Yan Zhang Qian Zhang Zhaoyang Zhang School of Communication and Information Engineering Shanghai University Shanghai China Key Laboratory of Advanced Display and System Applications Ministry of Education Shanghai China School of Information Engineering Anhui University of Finance and Economics Bengbu China

Multiview video plus depth (MVD) is a new 3D video format that would support 3D video applications. The primary goals are the high-quality reconstruction of an arbitrary number of views for 3D television (3DTV) and free viewpoint television (FTV). Its quality depends highly on the quality of depth image, a depth compression base B-spline interpolation is proposed for MVD to improve the 3D video coding (3DVC). The depth map is down sampling prior to multiview video coding (MVC) encoding and up sampling after decoding. The results investigated by objective as well as subjective evaluations over several multi-view test sequences imply that the proposed methods reduce the bit-rate for depth coding and achieve better rendering quality.

关键词： Encoding Three dimensional displays Rendering (computer graphics) Low pass filters Nonlinear filters Maximum likelihood detection Bit rate

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MDS investigation on the heat transfer properties of CNT micro-channel cooler

MDS investigation on the heat transfer properties of CNT mic...

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3rd Electronics system Integration Technology Conference, ESTC 2010

作者： Zhang, Yan Wang, Shun Fan, Jing-Yu Liu, Johan Key Laboratory of Advanced Display and System Applications School of Mechatronics Engineering and Automation Shanghai University Shanghai 200072 China Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China SMIT Center and Bionano Systems Laboratory Department of Microtechnology and Nanoscience Chalmers University of Technology SE-412 96 Gothenburg Sweden SHT Smart High Tech AB Fysikgränd 3 Se 412 96 Gothenburg Sweden

ISBN: (纸本)9781424485536

With the continuously increasing packaging density, the corresponding techniques for heat dissipation are vital to high performance components. During the system operation, the heat generated by components must be efficiently transferred outside of the electronic package. To meet the heat removal requirement of the electronic devices with a high power, several liquid cooling schemes have been suggested, among which the micro-channel cooler have gained the most attention. Simultaneously, the carbon nanotube (CNT) has attracted a significant interest in the material properties and exploratory application. Some studies have been recently conducted to evaluate the thermal performance of the CNTs and their applicability for heat removal in integrated circuit (IC) devices. By utilizing the adhesive transfer process to form the CNT bundles as the fins during the micro-channel development, the devices can be immune from the high temperature required by the CNT growth process. In the present paper, the interface heat transfer in the CNT-based micro-channel cooler has been investigated. The thermal resistances introduced by the interface between the CNT and the epoxy due to adhesive transfer and the interface between the CNT and water have been simulated by molecular dynamics simulation (MDS) method. And the thermal resistance at the interface between the CNT and the epoxy is about 1.0-1.5 × 10-8Km2/W. The obtained MDS results are likely to provide the microscopic understanding of the thermal performance of the CNT micro-channel cooler as well as provide references to the macroscopic evaluation of the thermal efficiency for the micro-channel cooler design and optimization.

关键词： Carbon nanotubes

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Polymer nanofiber based continuous metal phase composite for thermal management applications

Polymer nanofiber based continuous metal phase composite for...

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Electronics system-Integration Technology Conference, ESTC

作者： Björn Carlberg Johan Liu Li-Lei Ye Department of Microtechnology and Nanoscience (MC2) Chalmers University of Technology Gothenburg Sweden Key Laboratory of Advanced Display and System Applications & SMIT Center Shanghai University Shanghai China SHT Smart High-Tech AB Gothenburg Sweden

A new composite design approach for thermal interface materials is presented. A porous electrospun nanofiber network composed of temperature stable polyimide was infiltrated with liquid phase indium at a pressure of 30 MPa. The polymer phase defines composition and geometry, while the continuous metal phase gives binding to surfaces and high thermal conductivity. The composite was characterized by assembly of tri-layer copper/TIM/copper sandwich structures and subsequent xenon flash measurements extracting the thermal properties of the intermediate TIM layer. The interfacial contact resistance was found to be 8 Kmm 2 /W and the thermal conductivity was 28 W/mK, indicating the potential for use in thermal management applications.

关键词： Thickness measurement Copper Materials reliability Detectors Thermal conductivity Phase measurement Polymers

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