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Precipitation of α Phase in the Massive and Feathery Structures in TiAl Alloys during Aging in the Single α Field

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Journal of Materials Science & Technology 1999年第5期15卷 469-472页

作者： Weijun ZHANG and Glloliang CHEN(state key laboratory for Advanced Metals and Materials, University of Science and Technology {3., {3. 100083. china To whom correspondence should be addressed ) Univ Sci & Technol beijing State Key Lab Adv Met & Mat Beijing 100083 Peoples R China

Precipitation of α-phase in massive and feathery microstructures was studied during aging in the single α field. It was found that the α-phase mainly precipitated along the γ-plate interfaces as laths in the feathery structure, while it nucleated at various sites in the massive structure in the form of particles and dominantly as plates. Precipitation of α-plates in the massive structure occurred by the difFusional ledge mechanism. The γm→α reaction proceeded by the growth of previously nucleated α-precipitates, and chiefly by the development of new α-plates

关键词： TiAl Precipitation of Field Phase in the Massive and Feathery Structures in TiAl Alloys during Aging in the Single

A five-fold pig bacterial artificial chromosome library:a resource for positional cloning and physical mapping

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Progress in Natural Science:Materials International 2006年第08期16卷 889-892页

作者： LIU Wei, ZHANG Ying, LIU Zhaoliang, GUO Li, WANG Xiaobo, FEI Jing, FENG Jidong, ZHAO Rui, HU Xiaoxiang and LI Ning (The state key laboratory for Agro-Biotechnology, College of Biology,{3. Agricultural University, beijing 100094,{3. College of Animal Science and Technology,{3. Agricultural University, beijing 100094,{3.) [a]The state key laboratory for Agno-Biotechnology College of Biology China Agricultural University Beijing China [b]College of Animal Science and Technology China Agricultural University Beijing China

A pig BAC library was constructed with genomic DNA from a male Erhualian pig. After partial digestion with HindⅢor BamHⅠthe fragments obtained were cloned into the pBeloBAC11 vector. The library consists of 1843.0 clones which stored in 480 pieces 3.4-well plates (20 plates per superpool). A two-step 4-dimension PCR screening system was established to screen the positive clones. An average insert size of 128 kb was estimated from 105 randomly isolated clones, which indicates that the library is more than five times of genomic coverage. For the demonstration of the probability to pick out any unique genes or DNA markers from the library, 10 single-copy genes were screened out and the positive clones were yielded between 1 and 8 with an average of 3.6. Positive superpools were obtained for 3. microsatellite markers selected from different regions of pig genome. The number of positive superpools for each marker varies from 1 to 9 with an average of 4.78. This BAC library provides an additional resource for pig physical mapping and gene identifica-

关键词： pig BAC library PCR screening system.

Optimization of gasoline hydrocarbon compositions for reducing exhaust emissions

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Journal of Environmental Sciences 2009年第9期21卷 1208-1213页

作者： SHEN Yitao,SHUAI Shijin,WANG Jianxin,XIAO Jianhua state key laboratory of Automotive Safety and Energy,Tsinghua University,{3. 100084,china [a]state key laboratory of Automotive Safety and Energy Tsinghua University Beijing 100084 China

Effects of hydrocarbon compositions on raw exhaust emissions and combustion processes were studied on an engine test bench. The optimization of gasoline hydrocarbon composition was discussed. As olefins content increased from 10.0% to 25.0% in volume, the combustion duration was shortened by about 2 degree crank angle （°CA）, and the engine-out THC emission was reduced by about 15%. On the other hand, as aromatics content changed from 3..0% to 45.0%, the engine-out NOx emissions increased by 4%. An increment in olefins content resulted in a slight increase in engine-out CO emission, while the aromatics content had little effect on engine-out total hydrocarbon （THC） and CO emissions. Over the new European driving cycle （NEDC）, the THC, NOx and CO emissions of fuel with 25.0% olefins and 3..0% aromatics were about 45%, 21% and 19% lower than those of fuel with 10.0% olefins and 40.0% aromatics, respectively. The optimized gasoline compositions for new engines and new vehicles have low aromatics and high olefins contents.

关键词： optimization hydrocarbon composition exhaust emissions olefins aromatics

Soluble expression and characterization of a GFP-fused pea actin isoform (PEAc1)

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Cell Research 2004年第5期14卷 407-414页

作者： Ai Xiao LIU*, Shao Bin ZHANG*, Xiao Jing XU, Dong Tao REN, Guo Qin LIU** state key laboratory of Plant Physiology and Biochemistry, College of Biological Science,{3. Agricultural University, beijing 100094,{3.. state key laboratory of Plant Physiology and Biochemistry College of Biological Science China Agricultural University Beijing 100094 China.

A pea actin isoform PEAc1 with green fluorescent protein (GFP) fusion to its C-terminus and His-tag to its N- terminus, was expressed in prokaryotic cells in soluble form, and highly purified with Ni-Chelating SepharoseTM Fast Flow column. The purified fusion protein (PEAc1-GFP) efficiently inhibited DNase I activities before polymerization, and activated the myosin Mg-ATPase activities after polymerization. The PEAc1-GFP also polymerized into green fluorescent filamentous structures with a critical concentration of 0.75 μM. These filamentous structures were labeled by TRITC-phalloidin, a specific agent for staining actin microfilaments, and identified as having 9 nm diameters by negative staining. These results indicated that PEAc1 preserved the essential characteristics of actin even with His-tag and GFP fusion, suggesting a promising potential to use GFP fusion protein in obtainning soluble plant actin isoform to analyze its physical and biochemical properties in vitro. The PEAc1-GFP was also expressed in tobacco BY2 cells, which offers a new pathway for further studying its distribution and function in vivo.

关键词： actin isoform polymerization DNase I inhibition myosin Mg-ATPase activation expression.

Stratigraphic thermohistory and its implications for regional geoevolution in the Tarim Basin,NW china

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Science china Earth Sciences 2010年第10期53卷 1495-1505页

作者： WANG TieGuan1,DAI ShiFeng2,LI MeiJun1,ZHANG WeiBiao1,3.Qiu NanSheng1 & WANG GuangLi1 1 state key laboratory of Petroleum Resources and Prospecting,{3. University of Petroleum,beijing 102249,{3. 2 state key laboratory of Coal Resources & Safe Mining,{3. University of Mining & Technology,beijing 100083.{3. 3.Exploration Research Center,Exploration & Development Institute,{3. Petrochemical Corporation,beijing 100083.{3. 1. state key laboratory of Petroleum Resources and Prospecting China University of Petroleum Beijing 102249 China2. State Key Laboratory of Coal Resources & Safe Mining China University of Mining & Technology Beijing 100083 China3. Exploration Research Center Exploration & Development Institute China Petrochemical Corporation Beijing 100083 China

Fourteen vitrinite reflectance profiles from the Tarim Basin,NW china,show that the vitrinite reflectance profiles of individual wells follow a faulted and dislocated dual-stage pattern in the eastern section of the Tazhong Uplift and in the Tabei *** reflectance values in these profiles change sharply at the unconformity beneath the Lower Carboniferous Bachu or Upper Devonian Donghetang Formations,where the overlying Triassic to Carboniferous strata are still in a mature phase within the "liquid oil window".However,the underlying Lower Paleozoic reached the overmature phase beyond the "liquid oil window" towards the end of the Silurian,or in the Early Devonian at the *** the vitrinite reflectance profiles are attributed to a continuous,single-stage pattern in the western section of the Tazhong Uplift,in which the Lower Paleozoic is also in an overmature phase,their overmaturity would have been achieved relatively late in geological *** stratigraphic thermohistory has the following implications to regional geoevolution:(1) The overmature Lower Ordovician to Cambrian strata in the eastern section of the Tazhong Uplift and in the Tabei Uplift,as well as in the Manjiaer Depression,could not have acted as the source kitchen for normal oil(so-called black oil);(2) The dissimilarity in vitrinite reflectance profiles between the eastern and western sections of the Tazhong Uplift reveals Early Paleozoic paleotectonic features,i.e.,lower at the east and higher at the west,whereas recent tectonic features formed since the Late Paleozoic are in reverse,i.e.,higher in the east and lower at the west;(3. Reconstruction of the denuded thickness of sediments overlying the Lower Ordovician strata suggests reconsideration on the paleotectonic features in the Tarim Basin;(4) Based on the sustained duration of the "liquid oil window" for overmature source beds,it is predicted that the Suntuoguole Lower Uplift between the Awati and Manjiaer Depressions is a

关键词： vitrinite reflectance profile faulted and dislocated dual-stage pattern paleotectonic features sustained "liquid oil window" period source kitchen

Decoding algorithms for shortened-extended turbo product codes in WiMAX systems

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Science in china(Series F) 2009年第12期52卷 2415-2423页

作者： XU ChangLong1,3.4, YANG Wei1,2 & YE WeiChen4 1 state key laboratory of Networking and Switching Technology, {3. University of Posts and Telecommunications, {3. 100044, china 2 state key laboratory of Rail Traffic Control and Safety, {3. Jiaotong University, {3. 100044, china 3.National Mobile Communications Research laboratory, Southeast University, Nanjing 210096, china 4 Intel Corporation, {3. Kerry Center, Guanghua Road 1, {3. 100020, china state key laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications Beijing 100044 China state key laboratory of Rail Traffic Control and Safety Beijing Jiaotong University Beijing 100044 China National Mobile Communications Research laboratory Southeast University Nanjing 210096 China Intel Corporation Beijing Kerry Center Guanghua Road 1 Beijing 100020 China

The component codes of turbo product codes in WiMAX systems are extended Hamming codes and single parity check codes as well as their shortened forms, In this paper, three novel iterative decoding algorithms based on Chase, MAP algorithms and their combination are proposed for shortened-extended turbo product codes. The iterative decoding algorithm based on Chase algorithm is proposed to reduce the decoding complexity without any performance loss. An efficient MAP algorithm is then proposed to decode the component codes of shortened single parity check codes and shortened-extended Hamming codes. A comprehensive performance comparison of the proposed decoding schemes is conducted for three typical classes of turbo product codes in WiMAX OFDMA systems. The suitable decoding algorithms are recommended for different classes based on the simulation results.

关键词： block code product code iterative decoding

Research and development on transonic compressor of high pressure ratio turbocharger for vehicle internal combustion engines

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Science china(Technological Sciences) 2010年第7期53卷 1817-1823页

作者： ZHENG XinQian, ZHANG YangJun & YANG MingYang state key laboratory of Automotive Safety and Energy, Tsinghua University, {3. 100084, china 1. state key laboratory of Automotive Safety and Energy Tsinghua University Beijing 100084 China

The pressure ratio required for a turbocharger centrifugal compressor increases with internal combustion engine power density. High pressure ratio causes a transonic flow field at the impeller inducer. Transonic flow narrows the stable flow range and de-teriorates stage efficiency. In this work, an advanced high pressure ratio transonic compressor was designed. The experimental results show that the maximum pressure ratio of this turbocharger is about 4.2, the maximum efficiency is above 80% and the stable flow range at the designed rotating speed is up to 3.%. A turbocharger with this transonic compressor has been applied to some vehicle research actually, and improved power density by 40%.

关键词： turbocharger internal combustion (IC) engine compressor high pressure ratio transonic

Fusion tracking in color and infrared images using joint sparse representation

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Science china(Information Sciences) 2012年第3期55卷 590-599页

作者： LIU HuaPing1,2,3.& SUN FuChun1,2,3.1Department of Computer Science and Technology, Tsinghua University, beijing 100084, china 2state {3. laboratory of Intelligent Technology and Systems, beijing 100084, china 3.singhua National laboratory for Information Science and Technology, beijing 100084, china 1. Department of Computer Science and Technology Tsinghua University Beijing 100084 China2. State Key Laboratory of Intelligent Technology and Systems Beijing 100084 China3. Tsinghua National Laboratory for Information Science and Technology Beijing 100084 China

Currently sparse signal reconstruction gains considerable interest and is applied in many fields. In this paper, a similarity induced by joint sparse representation is designed to construct the likelihood function of particle filter tracker so that the color visual spectrum and thermal spectrum images can be fused for object tracking. The proposed fusion scheme performs joint sparse representation calculation on both modalities and the resultant tracking results are fused using min operation on the sparse representation coefficients. In addition, a co-learning approach is proposed to update the reference templates of both modality and enhance the tracking robustness. The proposed fusion scheme outperforms state-of-the-art approaches, and its effectiveness is verified using OTCBVS database.

关键词： joint sparse representation fusion tracking color image infrared image

A tetrahedral data model for unstructured data management

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Science china(Information Sciences) 2010年第8期53卷 1497-1510页

作者： LI Wei & LANG Bo state key laboratory of Software Development Environment, Beihang University, {3. 100191, china 1. state key laboratory of Software Development Environment Beihang University Beijing 100191 China

This paper proposes a tetrahedral data model for unstructured data management. The model defines the four components of unstructured data including: basic attributes, semantic characteristics, low-level features and raw data on its four facets, and the relations between these components. The internal implementation structure of the model and the data query language are designed and briefly introduced. This model provides a unified, integrated and associated description for different kinds of unstructured data, and supports intelligent data services such as associated retrieval and data mining. An example is given to demonstrate how to use the model for describing and manipulating data from a sample video base.

关键词： unstructured data data model query language associated retrieval intelligent services