期刊文献+
共找到48篇文章
< 1 2 3 >
每页显示 20 50 100
大阵列数光阵列发生器研究
1
作者 聂守平 魏晓燕 陈伯荣 《激光杂志》 CAS CSCD 北大核心 2001年第5期36-37,共2页
研究了产生大阵列数的光阵列发生器的设计与加工 ,设计并加工了产生一维 6 4点阵和二维 40 96点阵的光阵列发生器。
关键词 阵列发生器 阵列 光栅
下载PDF
小F数衍射微透镜阵列光学性能研究
2
作者 陈四海 易新建 +2 位作者 刘鲁勤 何苗 孔令斌 《光子学报》 EI CAS CSCD 北大核心 2001年第5期608-613,共6页
本文基于小光点扫描 ,在国内首次提出了一种测试小 F数衍射微透镜阵列光学性能的方法 .利用光通信用半导体激光器和探测器建立了一套测试系统 ,并对所研制的大阵列 ,小单元尺寸的多相位菲涅耳衍射微透镜阵列的衍射效率和点扩散函数进行... 本文基于小光点扫描 ,在国内首次提出了一种测试小 F数衍射微透镜阵列光学性能的方法 .利用光通信用半导体激光器和探测器建立了一套测试系统 ,并对所研制的大阵列 ,小单元尺寸的多相位菲涅耳衍射微透镜阵列的衍射效率和点扩散函数进行了测试 .结果表明 ,衍射微透镜实际衍射光斑比理论衍射受限光斑扩展不大 ,8相位和 1 6相位石英微透镜的衍射效率分别高达 80 .2 %和 87.5 % ,说明本实验室对多相位的设计理论和制作工艺已基本掌握 。 展开更多
关键词 小F衍射微透镜阵列 衍射效率 点扩散函 小光点扫描 二元光学 微小光学 红外焦平面阵列 微光学传感器阵列
下载PDF
采用液晶空间光调制器的可控性阵列菲涅耳波带片 被引量:25
3
作者 陈怀新 魏宏刚 +1 位作者 陈祯培 吴科 《光子学报》 EI CAS CSCD 北大核心 2001年第5期562-566,共5页
利用液晶空间光调制器的光学调制特性 ,实现阵列数与焦长可调控的阵列菲涅耳波带片 ,并给出了理论分析和实验结果 ,该方法操作简单。
关键词 液晶空间光调制器 实时可控性 阵列菲涅耳波带片 衍射光学组件 阵列 焦长
下载PDF
Ex⁃situ Measurement of Internal Deformation in Ball Grid Array Package with Digital Volume Correlation
4
作者 WANG Long GAO Zizhan +3 位作者 ZHANG Xuanhao LIU Qiaoyu HOU Chuantao XING Ruisi 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2024年第5期609-620,共12页
In spacecraft electronic devices,the deformation of solder balls within ball grid array(BGA)packages poses a significant risk of system failure.Therefore,accurately measuring the mechanical behavior of solder balls is... In spacecraft electronic devices,the deformation of solder balls within ball grid array(BGA)packages poses a significant risk of system failure.Therefore,accurately measuring the mechanical behavior of solder balls is crucial for ensuring the safety and reliability of spacecraft.Although finite element simulations have been extensively used to study solder ball deformation,there is a significant lack of experimental validation,particularly under thermal cycling conditions.This is due to the challenges in accurately measuring the internal deformations of solder balls and eliminating the rigid body displacement introduced during ex-situ thermal cycling tests.In this work,an ex-situ three-dimensional deformation measurement method using X-ray computed tomography(CT)and digital volume correlation(DVC)is proposed to overcome these obstacles.By incorporating the layer-wise reliability-guided displacement tracking(LW-RGDT)DVC with a singular value decomposition(SVD)method,this method enables accurate assessment of solder ball mechanical behavior in BGA packages without the influence of rigid body displacement.Experimental results reveal that BGA structures exhibit progressive convex deformation with increased thermal cycling,particularly in peripheral solder balls.This method provides a reliable and effective tool for assessing internal deformations in electronic packages under ex-situ conditions,which is crucial for their design optimization and lifespan predictions. 展开更多
关键词 ball grid array(BGA)packages digital volume correlation ex-situ rigid body displacement thermal cycling test
下载PDF
微热管阵列热回收在空调系统中的应用研究 被引量:1
5
作者 何天宇 吕广 +3 位作者 王伟迪 刘峰兵 塞莱克·努尔别克 张晶莹 《建材与装饰》 2019年第33期216-217,共2页
热回收技术对于空调系统节能具有重要意义。本文以微热管阵列热回收装置为对象,研究了平板微热管阵列排数、室内外空气温差和空气流量对热回收效率的影响程度。结果表明热回收效率会随着室内外空气温差和微热管阵列排数的增加而增加,然... 热回收技术对于空调系统节能具有重要意义。本文以微热管阵列热回收装置为对象,研究了平板微热管阵列排数、室内外空气温差和空气流量对热回收效率的影响程度。结果表明热回收效率会随着室内外空气温差和微热管阵列排数的增加而增加,然而热回收效率增长率会逐渐将小。随着空气流量的增加,热回收效率呈现出不断减小的趋势。在实际应用中,对于该装置,选择合适的风量对于空调系统节能尤为重要。 展开更多
关键词 微热管阵列 热回收 温度效率 室内外温差 空气流量 阵列
下载PDF
Stochastic resonance based on correlation coefficient in parallel array of threshold devices 被引量:2
6
作者 王友国 吴乐南 《Journal of Southeast University(English Edition)》 EI CAS 2006年第4期479-483,共5页
The phenomenon of stochastic resonance (SR) based on the correlation coefficient in a parallel array of threshold devices is discussed. For four representative noises: the Gaussian noise, the uniform noise, the Lap... The phenomenon of stochastic resonance (SR) based on the correlation coefficient in a parallel array of threshold devices is discussed. For four representative noises: the Gaussian noise, the uniform noise, the Laplace noise and the Cauchy noise, when the signal is subthreshold, noise can improve the correlation coefficient and SR exists. The efficacy of SR can be significantly enhanced and the maximum of the correlation coefficient can dramatically approach to one as the number of the threshold devices in the parallel array increases. Two theorems are presented to prove that SR has some robustness to noises in the parallel array. These results further extend the applicability of SR in signal processing. 展开更多
关键词 stochastic resonance correlation coefficient threshold array
下载PDF
Reservoir information extraction using a fractional Fourier transform and a smooth pseudo Wigner-Ville distribution 被引量:5
7
作者 王祝文 王晓丽 +3 位作者 向旻 刘菁华 张雪昂 杨闯 《Applied Geophysics》 SCIE CSCD 2012年第4期391-400,494,495,共12页
Currently, it is difficult for people to express signal information simultaneously in the time and frequency domains when analyzing acoustic logging signals using a simple-time or frequency-domain method. It is diffic... Currently, it is difficult for people to express signal information simultaneously in the time and frequency domains when analyzing acoustic logging signals using a simple-time or frequency-domain method. It is difficult to use a single type of time-frequency analysis method, which affects the feasibility of acoustic logging signal analysis. In order to solve these problems, in this paper, a fractional Fourier transform and smooth pseudo Wigner Ville distribution (SPWD) were combined and used to analyze array acoustic logging signals. The time-frequency distribution of signals with the variation of orders of fractional Fourier transform was obtained, and the characteristics of the time-frequency distribution of different reservoirs under different orders were summarized. Because of the rotational characteristics of the fractional Fourier transform, the rotation speed of the cross terms was faster than those of primary waves, shear waves, Stoneley waves, and pseudo Rayleigh waves. By choosing different orders for different reservoirs according to the actual circumstances, the cross terms were separated from the four kinds of waves. In this manner, we could extract reservoir information by studying the characteristics of partial waves. Actual logging data showed that the method outlined in this paper greatly weakened cross-term interference and enhanced the ability to identify partial wave signals. 展开更多
关键词 Fractional Fourier transform smooth pseudo Wigner-Ville distribution arrayacoustic logging signal processing RESERVOIRS
下载PDF
浅析一道高考题
8
作者 李永珊 《科技资讯》 2006年第28期129-129,共1页
本文通过分析解决本题,从而导出一个更一般的结论,即用数字1,2,3,4,…,n形成数阵时,S=b1+b2+…+的一般通式,以供同行们商榷。
关键词 数阵列
下载PDF
Design of a 4.224GHz Quadrature LC-VCO 被引量:1
9
作者 李志升 李巍 李宁 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2008年第2期251-255,共5页
A 4. 224GHz quadrature voltage-controlled oscillator (QVCO) applied in MB-OFDM UWB synthesizers is implemented in 0.18μm RF-CMOS technology. An improved structure of the QVCO is presented for better phase noise. A ... A 4. 224GHz quadrature voltage-controlled oscillator (QVCO) applied in MB-OFDM UWB synthesizers is implemented in 0.18μm RF-CMOS technology. An improved structure of the QVCO is presented for better phase noise. A novel configuration of a MOS varactor is designed for good linearity of K as well as a new digital capacitor controlled array topology with lower parasitic capacitance and lower Ron. Measurement results show a phase noise of - 90.4dBc/Hz at 100kHz offset and - 116.7dBc/Hz at 1MHz offset from a carrier close to 4. 224GHz. The power dissipation is 10. 55mW from a 1.8V supply. 展开更多
关键词 UWB quadrature VCO phase noise VARACTOR DCCA quadrature performance
下载PDF
Computer Simulation of Compensation Method for Infrared Focal Plane Array
10
作者 康长赓 《Journal of Beijing Institute of Technology》 EI CAS 2000年第3期330-334,共5页
A major motivation for this work is to investigate a method of computer simulation for compensating fixed pattern noise of the infrared focal plane arrays. A mathematical model of the output signal of focal plane arra... A major motivation for this work is to investigate a method of computer simulation for compensating fixed pattern noise of the infrared focal plane arrays. A mathematical model of the output signal of focal plane array was established; a compensating algorithm utilizing reference source was derived and simulating programs were designed. The images of compensating process verify the influence of nonuniformity of responsibility and offset on fixed pattern noise. The result show that simulating method of investigating compensation technology for focal plane arrays is feasible, the generated images and methods can be used to the study of image recognition. 展开更多
关键词 computer simulation mathematical model infrared focal plane array fixed pattern noise NONUNIFORMITY COMPENSATION
下载PDF
NON-UNIFORM LINEAR ARRAY CONFIGURATION FOR MIMO RADAR
11
作者 彭珍妮 贲德 +1 位作者 张弓 顾海光 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2011年第2期152-156,共5页
Array configuration of multiple-input multiple-output (MIMO) radar with non-uniform linear array (NLA) is proposed. Unlike a standard phased-array radar where NLA is used to generate thinner beam patterns, in MIMO... Array configuration of multiple-input multiple-output (MIMO) radar with non-uniform linear array (NLA) is proposed. Unlike a standard phased-array radar where NLA is used to generate thinner beam patterns, in MIMO radar the property of NLA is exploited to get more distinct virtual array elements so as to improve pa- rameter identifiability, which means the maximum number of targets that can be uniquely identified by the radar. A class of NLA called minimum redundancy linear array (MRLA) is employed and a new method to construct large MRLAs is descrihed. The numerical results verify that compared to uniform linear array (ULA) MIMO radars, NLA MIMO radars can retain the same parameter identifiability with fewer physical antennas and achieve larger aperture length and lower Cramer-Rao bound with the same number of the physical antennas. 展开更多
关键词 MIMO radar parameter identifiability non-uniform linear array virtual array element array con-figuration
下载PDF
SS-SERA:An improved framework for architectural level soft error reliability analysis 被引量:2
12
作者 成玉 马安国 +2 位作者 王永文 唐遇星 张民选 《Journal of Central South University》 SCIE EI CAS 2012年第11期3129-3146,共18页
Integrated with an improved architectural vulnerability factor (AVF) computing model, a new architectural level soft error reliability analysis framework, SS-SERA (soft error reliability analysis based on SimpleSca... Integrated with an improved architectural vulnerability factor (AVF) computing model, a new architectural level soft error reliability analysis framework, SS-SERA (soft error reliability analysis based on SimpleScalar), was developed. SS-SERA was used to estimate the AVFs for various on-chip structures accurately. Experimental results show that the AVFs of issue queue (IQ), register update units (RUU), load store queue (LSQ) and functional unit (FU) are 38.11%, 22.17%, 23.05% and 24.43%, respectively. For address-based structures, i.e., levell data cache (LID), DTLB, level2 unified cache (L2U), levell instruction cache (LII) and ITLB, AVFs of their data arrays are 22.86%, 27.57%, 14.80%, 8.25% and 12.58%, lower than their tag arrays' AVFs which are 30.01%, 28.89%, 17.69%, 10.26% and 13.84%, respectively. Furthermore, using the AVF values obtained with SS-SERA, a qualitative and quantitative analysis of the AVF variation and predictability was performed for the structures studied. Experimental results show that the AVF exhibits significant variations across different structures and workloads, and is influenced by multiple microarchitectural metrics and their interactions. Besides, AVFs of SPEC2K floating point programs exhibit better predictability than SPEC2K integer programs. 展开更多
关键词 soft error architectural vulnerability factor (AVF) AVF estimation model
下载PDF
Classification analysis of microarray data based on ontological engineering 被引量:2
13
作者 LI Guo-qi SHENG Huan-ye 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2007年第4期638-643,共6页
Background knowledge is important for data mining, especially in complicated situation. Ontological engineering is the successor of knowledge engineering. The sharable knowledge bases built on ontology can be used to ... Background knowledge is important for data mining, especially in complicated situation. Ontological engineering is the successor of knowledge engineering. The sharable knowledge bases built on ontology can be used to provide background knowledge to direct the process of data mining. This paper gives a common introduction to the method and presents a practical analysis example using SVM (support vector machine) as the classifier. Gene Ontology and the accompanying annotations compose a big knowledge base, on which many researches have been carried out. Microarray dataset is the output of DNA chip. With the help of Gene Ontology we present a more elaborate analysis on microarray data than former researchers. The method can also be used in other fields with similar scenario. 展开更多
关键词 Ontological engineering Data mining MICROARRAY Support vector machine (SVM)
下载PDF
The Sequential Continuity of Multiplication on a Class of Infinite Matrix Algebras
14
作者 赵玟亨 刘金霞 《Chinese Quarterly Journal of Mathematics》 CSCD 2002年第2期49-52,共4页
Let λ and μ are sequence spaces and have both the signed_weak gliding hump property, (λ,μ) be the algebra of the infinite matrix operators which transform λ into μ, in this paper, we study the strong? Mackey... Let λ and μ are sequence spaces and have both the signed_weak gliding hump property, (λ,μ) be the algebra of the infinite matrix operators which transform λ into μ, in this paper, we study the strong? Mackey? weak multiplier sequentially continuous problem of infinite matrix algebras (λ,μ). 展开更多
关键词 sequence spaecs infinite matrix MULTIPLIER sequential continuity
下载PDF
Bounds for Determinants of Quaternion Matrices
15
作者 黄礼平 蔡永裕 《Chinese Quarterly Journal of Mathematics》 CSCD 1996年第2期13-16,共4页
This paper improves and generalizes famous Fischer's inequality and Hadamard's inequality,gets precise estimation of bounds for the determinant of quaternion matrix.
关键词 quaternion matrices DETERMINANT INEQUALITY
下载PDF
Min-norm spatial spectrum based on acoustic vector-sensor linear array 被引量:2
16
作者 ZHANG Lan-yue YANG De-sen 《Journal of Marine Science and Application》 2006年第3期41-45,共5页
The high resolution of DOA(direction of arrival) estimation could be obtained by using the min-norm algorithm. In this paper, the expression of the min-norm spatial spectrum based on acoustic vector-sensor(AVS) li... The high resolution of DOA(direction of arrival) estimation could be obtained by using the min-norm algorithm. In this paper, the expression of the min-norm spatial spectrum based on acoustic vector-sensor(AVS) linear arrays was presented and simulation study was carried out. Results of simulations indicated that left/right ambiguity could be removed and better performance for DOA estimation was obtainable when dealing with sources close to endfire than using pressure hydrophone linear arrays, and the interelement spacing was allowed to exceed the half-wavelength upper limit. A three-element vector hydrophone linear array with two meters interspace was designed. The AVS experiment was carried out at Songhua Lake in Jinlin Province. Experimental results show a high resolution tracking of targets can be obtained using the rain-norm algorithm. 展开更多
关键词 acoustic vector-sensor linear array min-norm algorithm direction of arrival estimation
下载PDF
3-D NUMERICAL COMPUTATION OF JET ARRAY IMPINGEMENT WITH INITIAL CROSSFLOW 被引量:2
17
作者 LIYong-kang ZHANGJing-zhou TANXiao-ming 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2004年第2期128-133,共6页
The 3-D numerical computation of the flow and temperature fields for jet array impingement with initial crossflow investigates the effects of the jet-to-surface spacing, the impinging hole arrangement and the jet-to-c... The 3-D numerical computation of the flow and temperature fields for jet array impingement with initial crossflow investigates the effects of the jet-to-surface spacing, the impinging hole arrangement and the jet-to-crossflow mass flux ratio on heat transfer characteristics. The study shows that: (1) under the different jet-to-surface spacing, the impingement cooling with inline arrangement is better than that with staggered arrangement for a given jet-to-crossflow mass flux ratio;( 2 ) the value of jet-to-surface spacing impacts a complicated effect on the flow and heat transfer for jet array impingement; (3) as the ratio of crossflow-to-jet mass flux ratio increases, the cooling effectiveness on monotonous decrease for both inline and staggered arrangements at the same jet-to-surface spacing. 展开更多
关键词 jet impingement numerical calculation enhanced heat transfer
下载PDF
CONSTRUCTIONOFACLASSOFPNSEQUENCESWITHPRIMENUMBERPERIODSOF4t+1FORM
18
作者 Yang Fengfan Bi Guangguo Department of Radio Engineering,Southeast UniversityNanjing 210096,P.R.China 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 1996年第1期118-120,共3页
A class of new PN sequence with prime number periods of 4t +1 form (t is an integer)is constructed.The advantage of these PN sequencs over the m(M) sequence is their large number of alternative periods.They hav... A class of new PN sequence with prime number periods of 4t +1 form (t is an integer)is constructed.The advantage of these PN sequencs over the m(M) sequence is their large number of alternative periods.They have good pseudo random characteristics demonstrated by the expression of periodic autocorrelation function found out in this paper. 展开更多
关键词 CODING autocorrelation function MATRIX PN sequences quadratic element finite field
下载PDF
Digitalized Mirror Array and Its Application in Large Telescope:Principle and Case Studies
19
作者 CHEN Ying-Tian ZHANG Yang +5 位作者 HU Sen Ho Tso-Hsiu Boon Ham Lim Chen Sin Lim Kok Keong Chong Boon Kok Tan 《Communications in Theoretical Physics》 SCIE CAS CSCD 2009年第10期750-760,共11页
In this article, we report the principle and conceptual design of a fundamentally different technology in fabricating high precision aberration free optical devices. The tip-tilt of facet in a mirror array is produced... In this article, we report the principle and conceptual design of a fundamentally different technology in fabricating high precision aberration free optical devices. The tip-tilt of facet in a mirror array is produced by digitally controlled line-tilts of rows and columns. It has not only provided a cost-effective designing methodology in optical physics but also led to a much finer precision of 1 mili arc sec or less. As examples of the application of the proposed digitalised optics, two case studies have been given: a 10 m Schmidt telescope (off-axis) and an 8 m Cassegrain telescope (on-axis). 展开更多
关键词 tip-tilting line-tilting Schmidt telescope aberration correction cassegrain telescope
下载PDF
用PCA实现16位PWM
20
作者 Cygnal Inc. 《电子质量》 2002年第6期51-54,共4页
描述了如何使用PCA实现PWM波形,获得16位分辨率。
关键词 PCA 16位PWM 信号 可编程阵列
下载PDF
上一页 1 2 3 下一页 到第
使用帮助 返回顶部