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释“成” 被引量:1
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作者 李艳 《宁夏大学学报(人文社会科学版)》 2001年第6期32-34,共3页
许慎认为“成”的本义为“就”。然从“成”字的古文字字形结构、“成”字古义所透露出来的信息及“成”的词义引中线索等方面来考察,“成”的本义当为“城”,即用兵器守卫着的、能容纳民众的聚居地。另外,经过对“成”在其基本义基... 许慎认为“成”的本义为“就”。然从“成”字的古文字字形结构、“成”字古义所透露出来的信息及“成”的词义引中线索等方面来考察,“成”的本义当为“城”,即用兵器守卫着的、能容纳民众的聚居地。另外,经过对“成”在其基本义基础上 乳形成的一族同族字的考察,也发现这些同族字的意义都与“城邑”义有关,这又进一步证明“成”之本义非“城邑”义莫属。 展开更多
关键词 '成'字 '' 训沽 源流 同族
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Imaging simulation and analysis of attitude jitter effect on topographic mapping for lunar orbiter stereo optical cameras
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作者 CHEN Chen TONG Xiao-Hua +4 位作者 LIU Shi-Jie YE Zhen HUANG Chao-Wei WU Hao ZHANG Han 《红外与毫米波学报》 SCIE EI CAS CSCD 北大核心 2024年第5期722-730,共9页
The geometric accuracy of topographic mapping with high-resolution remote sensing images is inevita-bly affected by the orbiter attitude jitter.Therefore,it is necessary to conduct preliminary research on the stereo m... The geometric accuracy of topographic mapping with high-resolution remote sensing images is inevita-bly affected by the orbiter attitude jitter.Therefore,it is necessary to conduct preliminary research on the stereo mapping camera equipped on lunar orbiter before launching.In this work,an imaging simulation method consid-ering the attitude jitter is presented.The impact analysis of different attitude jitter on terrain undulation is conduct-ed by simulating jitter at three attitude angles,respectively.The proposed simulation method is based on the rigor-ous sensor model,using the lunar digital elevation model(DEM)and orthoimage as reference data.The orbit and attitude of the lunar stereo mapping camera are simulated while considering the attitude jitter.Two-dimensional simulated stereo images are generated according to the position and attitude of the orbiter in a given orbit.Experi-mental analyses were conducted by the DEM with the simulated stereo image.The simulation imaging results demonstrate that the proposed method can ensure imaging efficiency without losing the accuracy of topographic mapping.The effect of attitude jitter on the stereo mapping accuracy of the simulated images was analyzed through a DEM comparison. 展开更多
关键词 topographic mapping lunar orbiter stereo camera attitude jitter imaging simulation digital elevation model
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A Compact Direct Digital Frequency Synthesizer for the Rubidium Atomic Frequency Standard 被引量:1
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作者 曹晓东 倪卫宁 +2 位作者 袁凌 郝志坤 石寅 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2008年第9期1723-1728,共6页
A compact direct digital frequency synthesizer (DDFS) for system-on-chip implementation of the high precision rubidium atomic frequency standard is developed. For small chip size and low power consumption, the phase... A compact direct digital frequency synthesizer (DDFS) for system-on-chip implementation of the high precision rubidium atomic frequency standard is developed. For small chip size and low power consumption, the phase to sine mapping data is compressed using sine symmetry technique, sine-phase difference technique, quad line approximation technique,and quantization and error read only memory (QE-ROM) technique. The ROM size is reduced by 98% using these techniques. A compact DDFS chip with 32bit phase storage depth and a 10bit on-chip digital to analog converter has been successfully implemented using a standard 0.35μm CMOS process. The core area of the DDFS is 1.6mm^2. It consumes 167mW at 3.3V,and its spurious free dynamic range is 61dB. 展开更多
关键词 CMOS integrated circuit DDFS rubidium atomic frequency standard SOC
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A 1×4 Polymeric Digital Optical Switch Based on the Thermo-Optic Effect 被引量:1
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作者 唐奕 张昊 +2 位作者 杨建义 王明华 江晓清 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2006年第4期692-695,共4页
We present a 1 × 4 Y-branch digital optical switch in which S-bend variable optical attenuators are integrated. The S-bend waveguides, which are always introduced to connect the switch and the standard fiber arra... We present a 1 × 4 Y-branch digital optical switch in which S-bend variable optical attenuators are integrated. The S-bend waveguides, which are always introduced to connect the switch and the standard fiber array, are made use of and designed as variable optical attenuators. A compact device with low crosstalk and larger branching-angle is obtained. The device is fabricated on the thermo-optic polymer materials,and the performance of the device is measured. With an applied driving power of less than 200mW, the device has a low crosstalk of less than - 35dB at a wavelength of 1.55 μm. 展开更多
关键词 bend waveguide variable optical attenuator thermo-optic effect digital optical switch integrated optics
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10 Gbit/s PRBS tester implemented in FPGA 被引量:1
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作者 苗澎 王志功 《Journal of Southeast University(English Edition)》 EI CAS 2007年第4期516-519,共4页
The design of an FPGA( field programmable gate array) based programmable SONET (synchronous optical network) OC-192 10 Gbit/s PRBS (pseudo-random binary sequence) generator and a bit interleaved polarity 8 (BI... The design of an FPGA( field programmable gate array) based programmable SONET (synchronous optical network) OC-192 10 Gbit/s PRBS (pseudo-random binary sequence) generator and a bit interleaved polarity 8 (BIP-8) error detector is presented. Implemented in a parallel feedback configuration, this tester features PRBS generation of sequences with bit lengths of 2^7 - 1,2^10- 1,2^15 - 1,2^23 - land 2^31 - 1 for up to 10 Gbit/s applications with a 10 Gbit/s optical transceiver, via the SFI-4 (OC-192 serdes-framer interface). In the OC-192 frame alignment circuit, a dichotomy search algorithm logic which performs the functions of word alignment and STM-64/OC192 de-frame speeds up the frame sync logic and reduces circuit complexity greatly. The system can be used as a low cost tester to evaluate the performance of OC-192 devices and components, taking the replacement of precious commercial PRBS testers. 展开更多
关键词 bit interleaved polarity 8 BIP-8 synchronous digital hierarchy SDH FRAMER field programmable gate array (FPGA) pseudo-random binary sequence (PRBS)
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NOISE EFFECT ON CHARACTERISTICS OF FLIP FLOP SENSOR
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作者 姚素英 毛赣如 +1 位作者 曲宏伟 张维新 《Transactions of Tianjin University》 EI CAS 1998年第1期84-87,共4页
This paper presents a new class of semiconductor integrated sensor which consists of sensitive components and flip flop circuit. The sensors have high sensitivity and digital output. This paper describes the operatin... This paper presents a new class of semiconductor integrated sensor which consists of sensitive components and flip flop circuit. The sensors have high sensitivity and digital output. This paper describes the operating principle and structure of the sensor. And noise effect on characteristics of the sensor is analysed in detail. The modulated effect of the triangular wave voltage is quantified. As an example, an integrated pressure sensor is introduced and the experimental results agree with the theoretical analyses. 展开更多
关键词 flip flop sensor semiconductor integrated noise digital output
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Ordered and Ordered Hamilton Digraphs 被引量:1
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作者 WANGMU Jiang-shan YUAN Jun +1 位作者 LIN Shang-wei WANG Shi-ying 《Chinese Quarterly Journal of Mathematics》 CSCD 2010年第3期317-326,共10页
A digraph D is k-ordered if for every sequence S:v 1,v 2,…,v k of k distinct vertices,there exists a cycle C such that C encounters the vertices of S in the specified order.In particular,we say that D is k-ordered h... A digraph D is k-ordered if for every sequence S:v 1,v 2,…,v k of k distinct vertices,there exists a cycle C such that C encounters the vertices of S in the specified order.In particular,we say that D is k-ordered hamiltonian if for every sequence S:v 1,v 2,…,v k of k distinct vertices,there exists a hamiltonian cycle C such that the vertices of S are encountered on C in the specified order.In this paper,sufficient conditions for digraphs to be ordered and ordered hamiltonian have been given. 展开更多
关键词 DIGRAPHS k-ordered digraphs k-ordered hamiltonian digraphs
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Ultimate Composition of Main Chinese Power Coals 被引量:1
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作者 Wang Shichang 《Electricity》 2012年第3期30-33,共4页
Calculations and analyses are made for the ultimate composition of 158 Chinese power coals. The results reveal that the carbon content on as received basis, Cr, increases linearly with the increase of the low heating ... Calculations and analyses are made for the ultimate composition of 158 Chinese power coals. The results reveal that the carbon content on as received basis, Cr, increases linearly with the increase of the low heating value Qnot,a, on as received basis; the hydrogen content on as received basis, Hr, first increases with the increase of the volatile content on dry ash free basis Vdaf (Vdaf 〈 33.0%) and then decreases (Vdaf 〉 33.0%); the oxygen content on as received basis, Oar, increases linearly with the increase of Vau, ranging between 2.0% and 12.5%. By comparison, the nitrogen content on as received basis N of bituminous and lean coal is higher, while the sulfur content on as received basis Sar Of anthracite is higher than bituminous coal, lean coal and lignite. The hydrogen on as received basis Hr is important for the conversion between low heating value and high heating value on as received basis for Chinese power coals, and Sr is important for the calculation of high heating value from the oxygen bomb heat value for Chinese power coals. 展开更多
关键词 Chinese power coals ultimate composition DISTRIBUTION
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IMPROVING THE FREQUENCY RESOLUTION OF DIGITALLY SYNTHESIZED PERIODIC SIGNALS BY A SEQUENTIAL ADDRESSING SCHEME 被引量:2
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作者 Tian Xinguang Duan Miyi +1 位作者 Sun Chunlai Chen Hong 《Journal of Electronics(China)》 2008年第5期661-666,共6页
In the digital synthesis of wideband periodic signals using an Arbitrary Waveform Gen-erator(AWG),the frequency resolution and spectral complexity of the synthesized signals are com-monly limited by the memory capacit... In the digital synthesis of wideband periodic signals using an Arbitrary Waveform Gen-erator(AWG),the frequency resolution and spectral complexity of the synthesized signals are com-monly limited by the memory capacity and clock frequency of the AWG.This paper proposes a novel sequential addressing scheme and then presents several sequences to improve the frequency resolution of the synthesized periodic signals without changing their spectral envelopes and basic time-domain characteristics under the condition of a fixed memory capacity and a fixed clock fre-quency.The main idea of the scheme is using the address generator in an AWG to program and produce addresses to read fixed waveform data in variable order,and thus to generate waveforms of various periods and profiles.The scheme is applied in simulating signal scenarios for military com-munication countermeasure experiments,and achieves high performance. 展开更多
关键词 Digital synthesis Frequency resolution Spectral envelope Sequential addressing
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Influence of dehydrating agents on the oxidative carbonylation of methanol for dimethyl carbonate synthesis over a Cu/Y-zeolite catalyst 被引量:1
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作者 Dong-Ho Lee Jiin You +6 位作者 Je-Min Woo Jung Yoon Seo Young Cheol Park Jong-Seop Lee Hyunuk Kim Jong-Ho Moon Seung Bin Park 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2018年第5期1059-1063,共5页
The influence of the dehydration by metal oxides on the synthesis of dimethyl carbonate (DMC) via oxidative carbonylation of methanol was studied. A Cu/Y-zeolite catalyst was prepared by the ion exchange method from... The influence of the dehydration by metal oxides on the synthesis of dimethyl carbonate (DMC) via oxidative carbonylation of methanol was studied. A Cu/Y-zeolite catalyst was prepared by the ion exchange method from CuCl2.2H2O and the commercial NH4-form of the Y type zeolite, The catalyst was characterized by X-ray fluorescence (XRF), N2 adsorption (BET method), X-ray diffraction (XRD), and temperature-programmed de- sorption of ammonia (NH3-TPD) to evaluate its Cu and Cl content, surface area, structure, and acidity. Reaction tests were carried out using an autoclave (batch reactor) for 18 h at 403 K and 5.5 MPa (2CH3OH + 1/2O2 + CO (CH3O)2CO + H2O). The influence of various dehydrating agents (ZnO, MgO, and CaO) was examined with the aim of increasing the methanol conversion (XMeOH, MeOH conversion). The MeOH conversion increased upon addition of metal oxides in the order CaO 〉〉 MgO 〉 ZnO, with the DMC selectivity (SDMC) following the order MgO 〉 CaO 〉 ZnO. The catalysts and dehydrating agents were characterized before and after the oxidative carbonylation of methanol by thermogravimetric and differential thermogravimetric (TG/DTG), and XRD to con- firm that the dehydration reaction occurred via the metal oxide (MO + H2O →M(OH)2). The MeOH conversion increased from 8.7% to 14.6% and DMC selectivity increased from 39.0% to 53.1%, when using the dehydrating azent CaO. 展开更多
关键词 Carbon monoxide ZEOLITE CATALYST Dimethyl carbonate Oxidative carbonylation Dehydrating agent
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Numerical simulation of wrinkle phenomenon during multi-point forming process of shallow rectangle cup 被引量:3
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作者 裴永生 李明哲 +1 位作者 李雪 隋振 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2004年第3期300-304,共5页
In this paper, the principle of multi-point forming (MPF) technique is presented. One of the most serious defects, wrinkling, during the multi-point forming process of a shallow rectangle cup is discussed by means of ... In this paper, the principle of multi-point forming (MPF) technique is presented. One of the most serious defects, wrinkling, during the multi-point forming process of a shallow rectangle cup is discussed by means of numerical simulation on the shallow rectangle cup forming process. The effects of thickness, material of sheet metal and the pressure of the blank holder are investigated. Based on the simulation results, the reasons and control methods of wrinkling are pointed out. Moreover, the experiment on the multi-point die forming of the shallow rectangle cup by the MPF machine is done to validate the efficiency of the numerical simulation, and the result proves that the application of an elastic cushion in the forming can restrain wrinkling efficiently. 展开更多
关键词 multi-point forming WRINKLE numerical simulation shallow rectangle cup
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Determining Topographic Shielding from Digital Elevation Models for Cosmogenic Nuclide Analysis:a GIS Approach and Field Validation 被引量:8
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作者 LI Ying-kui 《Journal of Mountain Science》 SCIE CSCD 2013年第3期355-362,共8页
Topographic shielding of cosmic radiation flux is a key parameter in using cosmogenic nuclides to determine surface exposure ages or erosion rates. Traditionally, this parameter is measured in the field and uncertaint... Topographic shielding of cosmic radiation flux is a key parameter in using cosmogenic nuclides to determine surface exposure ages or erosion rates. Traditionally, this parameter is measured in the field and uncertainty and/or inconsistency may exist among different investigators. This paper provides an ArcGIS python code to determine topographic shielding factors using digital elevation models (DEMs). This code can be imported into ArcGIS as a geoprocessing tool with a user-friendly graphical interface. The DEM-derived parameters using this method were validated with field measurements in central Tian Shan. Results indicate that DEM-derived shielding factors are consistent with field-measured values. It provides a valuable tool to save fieldwork efforts and has the potential to provide consistent results for different regions in the world to facilitate the comparison of cosmogenie nuclide results. 展开更多
关键词 Cosmogenic nuclides Topographicshielding ARCGIS PYTHON Digital elevation models(DEMs)
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An Improved Method for Modeling Spatial Distribution of δD in Surface Snow over Antarctic Ice Sheet
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作者 WANG Yetang HOU Shugui +1 位作者 Bjom GRIGHOLM SONG Linlin 《Chinese Geographical Science》 SCIE CSCD 2009年第2期120-125,共6页
Using the recent compilation of the isotopic composition data of surface snow of Antarctic ice sheet, we proposed an improved interpolation method of δD, which utilizes geographical factors (i.e., latitude and altit... Using the recent compilation of the isotopic composition data of surface snow of Antarctic ice sheet, we proposed an improved interpolation method of δD, which utilizes geographical factors (i.e., latitude and altitude) as the primary predictors and incorporates inverse distance weighting (IDW) technique. The method was applied to a high-resolution digital elevation model (DEM) to produce a grid map of multi-year mean δD values with lkm spatial resolution for Antarctica. The mean absolute deviation between observed and estimated data in the map is about 5.4‰, and the standard deviation is 9‰. The resulting δD pattern resembles well known characteristics such as the depletion of the heavy isotopes with increasing latitude and distance from coast line, but also reveals the complex topographic effects. 展开更多
关键词 δD surface snow ice sheet ANTARCTICA
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Numbers in English and Chinese language use
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作者 ZHANG Wu-ping 《Sino-US English Teaching》 2007年第6期41-44,共4页
The cultural connotations of numbers in English and Chinese languages are demonstrated to discuss the grammatical functions of the numbers and their rhetoric usages. For a foreign language learner, it is essential tha... The cultural connotations of numbers in English and Chinese languages are demonstrated to discuss the grammatical functions of the numbers and their rhetoric usages. For a foreign language learner, it is essential that they know not. only the denotation of the numbers, but also the connotation of the numbers. Numbers frequently play an important role in dally communication. 展开更多
关键词 NUMBERS IDIOMS RHETORIC HYPERBOLE
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COMPARISON STUDY ON THE INTRASEASONAL VARIATIONS IN CIRCULATIONS AND PRECIPITATION MODULATED BY THE TROPICAL CYCLOGENESIS OVER SOUTH CHINA SEA-WESTERN PACIFIC DURING GUANGDONG FLOODING PERIOD
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作者 李春晖 万齐林 +2 位作者 郑彬 谷德军 林爱兰 《Journal of Tropical Meteorology》 SCIE 2011年第4期363-374,共12页
Based on tropical cyclone datasets from Shanghai Typhoon Institute of China Meteorological Administration,the National Centers for Environmental Prediction (NCEP,USA) reanalysis data and the rainfall records from 743 ... Based on tropical cyclone datasets from Shanghai Typhoon Institute of China Meteorological Administration,the National Centers for Environmental Prediction (NCEP,USA) reanalysis data and the rainfall records from 743 stations in China,the impacts of cyclogenesis number over the South China Sea and the western Pacific are studied on the 30-60-day oscillations in the precipitation of Guangdong during the flooding period.The year with more-than-normal (less-than-normal) tropical cyclogenesis is defined as a 'high year' ('low year').In light of the irregular periodic oscillations,the method used to construct the composite life cycle is based on nine consecutive phases in each of the cycles.Phases 1,3,5,and 7 correspond to,respectively,the time when precipitation anomalies reach theminimum,a positive transition (negative-turning-to-positive) phase,the maximum,and a negative transition phase.The results showed that the precipitation of the 30-60-day oscillations is associated with the interaction between a well-organized eastward propagation system from the Arabian Sea/Bay of Bengal and a westward-propagating system (with cyclonic and anticyclonic anomalies in the northwest-southeast direction) from the South China Sea to western Pacific during the high years,whereas the precipitation is affected during a low year by the circulation over the South China Sea and western Pacific (with cyclonic and anticyclonic anomalies in the northeast-southwest direction).During the high year,the warm and wet air mass from the ocean to the west and south are transported to Guangdong by westerly anomalies and an enclosed latitudinal cell,which ascends in the Northern Hemisphere low latitudes and descends in the Southern Hemisphere low latitudes.During the low year,the warm and wet air mass from the ocean to the south is transported to Guangdong by southwesterly wind anomalies and local ascending movements.Because the kinetic energy,westerly,easterly shift,vertical velocity and vapor transportation averaged over (109-119° E,10-20° N) is stronger in high years than those in low years,the precipitation of the 30-60-day oscillations in Guangdong is higher in high years than that in low years. 展开更多
关键词 cyclogenesis number over the South China Sea and western Pacific precipitation in Guangdong province 30-60-day oscillation
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Numerical Simulation on the Interaction of an Internal Solitary Wave with a Step-Type Topography
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作者 XU Zhaoting LI Qun CHEN Xu YU Jia 《Journal of Ocean University of China》 SCIE CAS 2008年第2期119-123,共5页
Based on a nonhydrostatic numerical ocean model developed by one of the authors, the interaction of an intemal solitary wave with a step-type topography was investigated. Over the step topography, the flow pattern cou... Based on a nonhydrostatic numerical ocean model developed by one of the authors, the interaction of an intemal solitary wave with a step-type topography was investigated. Over the step topography, the flow pattern could be classified into three categories: 1) the propagation and spatial structure of the internal solitary wave was little influenced by the bottom topography, 2) the internal solitary wave was significantly distorted by the blocking effect of the topography without the occurrence of wave breaking and 3) the internal solitary wave was broken as it encountered and passed over the bottom topography. A detailed description of the processes leading to wave breaking is given in this paper together with energy budget analysis. The results revealed that the maximum of the energy dissipation rate is no more than 40%, which is consistent with available experimental data. 展开更多
关键词 stratified flow intemal solitary wave energy dissipation
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Key technologies for the novel distributed numerical control integrated system 被引量:1
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作者 TAOGuibao LIUFei WANGShilong 《Journal of Chongqing University》 CAS 2004年第1期1-5,共5页
A novel distributed numerical control (DNC) integrated system based on plug-in software technology is proposed. It connects new or old numerical control (NC) machine tools which have inhomogeneous numerical control sy... A novel distributed numerical control (DNC) integrated system based on plug-in software technology is proposed. It connects new or old numerical control (NC) machine tools which have inhomogeneous numerical control systems with CAD/CAM system by CANbus network. A DNC computer is able to control 15 sets of NC machine tools reliably at the same time. The novel DNC system increases the efficiency of machine tools and improve the production management level by realizing non-paper production, agile manufacturing, networked manufacturing and so on in the near future. Key technologies to construct the novel DNC integrated system include the integration of inhomogeneous numerical control systems, NC program restart, and algorithm for communication competition. Such system has demonstrated successful applications in some corporations that have acquired good economic benefits and social effects. 展开更多
关键词 COMMUNICATION distributed numerical control CANBUS plug-in software program restart integrated system
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Quasi-Static Energy Recovery Logic with Single Power-Clock Supply
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作者 李舜 周锋 +2 位作者 陈春鸿 陈华 吴一品 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2007年第11期1729-1734,共6页
This paper presents a new quasi-static single-phase energy recovery logic (QSSERL), which unlike any other existing adiabatic logic family,uses a single sinusoidal supply-clock without additional timing control volt... This paper presents a new quasi-static single-phase energy recovery logic (QSSERL), which unlike any other existing adiabatic logic family,uses a single sinusoidal supply-clock without additional timing control volta- ges. This not only ensures lower energy dissipation, but also simplifies the clock design, which would be otherwise more complicated due to the signal synchronization requirement. It is demonstrated that QSSERL circuits operate as fast as conventional two-phase energy recovery logic counterparts. Simulation with an 8bit logarithmic look- ahead adder (LLA) using static CMOS,clocked CMOS adiabatic logic (CAL,an existing typical single-phase ener- gy recovery logic),and QSSERL,under 128 randomly generated input vectors,shows that the power consumption of the QSSERL adder is only 45% of that of the conventional static CMOS counterpart at 10MHz, and the QS- SERL adder achieves better energy efficiency than CAL when the input frequency finput is larger than 2MHz. 展开更多
关键词 energy recovery adiabatic logic low power digital CMOS VLSI
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Measurement of large deformation of nylon cord-rubber composite and effects of perpendicular loads on its stress-strain behaviors
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作者 张丰发 杜星文 于增信 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2003年第1期34-38,共5页
Effects of transverse loads on longitudinal stress strain behaviors and longitudinal constant tensile loads on transverse stress strain behaviors of single ply of nylon cord rubber composite are studied respectively u... Effects of transverse loads on longitudinal stress strain behaviors and longitudinal constant tensile loads on transverse stress strain behaviors of single ply of nylon cord rubber composite are studied respectively under biaxial tensile condition with cruciform specimen. Effects of transverse constant tensile load on longitudinal tensile mechanical properties are indistinctive compared with corresponding uniaxial longitudinal tensile mechanical properties. It can be relative to larger difference between longitudinal and transverse mechanical properties. Its dominating failure mode is typical fiber dominated mode; However, Experiment results indicate that transverse mechanical properties of nylon cord rubber composite with longitudinal constant tensile loads are distinct from its uniaxial transverse tensile mechanical properties. It can be attribute to action of longitudinal tension that makes material rigidify in the direction perpendicular to fiber, Mode of failure is representative of matrix dominated failure. For the measurement of large deformation up to 50 percent, a special CCD imaging method is employed in the experimental investigation that makes measurement of large deformations more precise. 展开更多
关键词 nylon cord rubber composite cruciform specimen large deformation biaxial tensile condition
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Experimental Research on Flash Boiling Spray of Dimethyl Ether
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作者 Peng Zhang 《Journal of Marine Science and Application》 2014年第4期416-421,共6页
The high-speed digital imaging technique is applied to observe the developing process of flash boiling spray of dimethyl ether at low ambient pressure, and the effects of nozzle opening pressure and nozzle hole diamet... The high-speed digital imaging technique is applied to observe the developing process of flash boiling spray of dimethyl ether at low ambient pressure, and the effects of nozzle opening pressure and nozzle hole diameter on the spray shape, spray tip penetration and spray angle during the injection are investigated. The experimental results show that the time when the vortex ring structure of flash boiling spray forms and its developing process are determined by the combined action of the bubble growth and breakup in the spray and the air drag on the leading end of spray; with the enhancement of nozzle opening pressure, the spray tip penetration increases and the spray angle decreases. The influence of nozzle hole diameter on the spray tip penetration is relatively complicated, the spray tip penetration is longer with a smaller nozzle hole diameter at the early stage of injection, while the situation is just opposite at the later stage of injection. This paper establishes that the variation of spray angle is consistent with that of nozzle hole diameter. 展开更多
关键词 dimethyl ether flash boiling spray high-speed digital imaging spray tip penetration spray angle vortex ring structure
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