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视场角限制下的攻击时间和角度三维矢量制导律设计
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作者 熊天昊 王长元 +2 位作者 张科 苏雨 郭正玉 《航空兵器》 CSCD 北大核心 2024年第4期49-56,共8页
为了提高导弹精确打击目标的能力,控制攻击时间和攻击角度三维制导问题在实际应用中具有重要的意义。针对这一问题,本文基于三维矢量制导模型提出了一种视场角约束下的攻击时间和攻击角度控制律。首先,通过将平面矢量制导律扩展至三维空... 为了提高导弹精确打击目标的能力,控制攻击时间和攻击角度三维制导问题在实际应用中具有重要的意义。针对这一问题,本文基于三维矢量制导模型提出了一种视场角约束下的攻击时间和攻击角度控制律。首先,通过将平面矢量制导律扩展至三维空间,提出了一种三维矢量攻击角度约束制导律;其次,在上述制导指令的拦截分量中引入剩余时间偏置项,设计了一种在视场角约束下的三维矢量制导律,并进行了稳定性分析。保证导弹能在视场角约束的条件下,以期望的攻击时间和角度击中目标,并且误差均小于0.01;最后,通过数值模拟验证了所设计制导律的正确性和有效性。 展开更多
关键词 导弹 矢量制导律 限制 攻击时间约束 攻击角度约束 耦合非线性
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带导引头视场限制的多约束导引律及剩余时间估计 被引量:11
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作者 马国欣 张友安 李君 《系统工程与电子技术》 EI CSCD 北大核心 2014年第8期1609-1613,共5页
具有攻击角度约束的导引律能够使导弹按指定方向打击目标,具有攻击时间约束的导引律能够使导弹按指定时间打击目标。相比于传统的导引方法(如比例导引律),此类导引律均带来额外的机动,从而可能导致目标超出导引头视场(即使对于静止目标... 具有攻击角度约束的导引律能够使导弹按指定方向打击目标,具有攻击时间约束的导引律能够使导弹按指定时间打击目标。相比于传统的导引方法(如比例导引律),此类导引律均带来额外的机动,从而可能导致目标超出导引头视场(即使对于静止目标)。针对该问题,利用余弦函数的非线性特性,首先构造了一种带有导引头视场限制及攻击角度约束偏置项的比例导引律,并推导了该导引律的剩余时间估计。然后通过附加剩余时间误差反馈项,得到了一种带导引头视场限制并同时具有攻击角度约束与攻击时间约束的导引律。仿真结果验证了所提方法的有效性。 展开更多
关键词 导引 导弹 攻击时间 攻击角度 限制
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具有高模场限制的异质纳米棒结构波导(英文) 被引量:3
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作者 杨鹏飞 姚建铨 +2 位作者 刘晓波 邴丕彬 邸志刚 《红外与激光工程》 EI CSCD 北大核心 2012年第6期1477-1480,共4页
现代光学及纳米光学的一个主要发展趋势是从理论和实验两方面探究用于突破传统衍射极限的亚波长级别的电磁波波导结构。表面等离子激源提供了解决此问题的有效突破口。文中根据异质波导结构的耦合以及锲型波导的表面等离子激发理论,提... 现代光学及纳米光学的一个主要发展趋势是从理论和实验两方面探究用于突破传统衍射极限的亚波长级别的电磁波波导结构。表面等离子激源提供了解决此问题的有效突破口。文中根据异质波导结构的耦合以及锲型波导的表面等离子激发理论,提出了异质纳米棒结构波导,该结构具有非常高的模场限制能力,对其传输的模式理论上可实现亚波长级别的限制能力。文中主要对此结构进行了数值仿真,分析了该波导结构的能量以及传输损耗,其结果表明该结构的模场限制能力可达到衍射极限的1/500,而且通过调整结构参数,将模场的传输距离延长到毫米级别。 展开更多
关键词 表面等离子激元 异质 亚波长 限制 波导
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具有场板和限制环的P^+N二极管击穿特性的研究
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作者 王荣 尚士奇 吴非 《微处理机》 1995年第1期61-64,共4页
本文从实验的角度研究了具有场板和场限制环的P+N二极管的击穿特性,给出了场环至主结的最佳间距与衬底浓度和结深的关系曲线。并从物理机制上对此进行了较深入的讨论。
关键词 限制 半导体二板管 P^+N结 击穿特性
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场限制环的安全环距设计原理 被引量:1
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作者 季超仁 陆景唐 +1 位作者 宋汉斌 董鸣 《固体电子学研究与进展》 CAS CSCD 北大核心 1996年第3期216-220,共5页
场限制环作为一种可与许多器件工艺相容的PN结终端得到了广泛应用。存在的一个问题是其效果随结构参数有过分敏感的变化。文中认为:作为设计指导思想的最佳环距原则是加重这一敏感性的重要原因。作为改进,提出了新的安全环距设计原... 场限制环作为一种可与许多器件工艺相容的PN结终端得到了广泛应用。存在的一个问题是其效果随结构参数有过分敏感的变化。文中认为:作为设计指导思想的最佳环距原则是加重这一敏感性的重要原因。作为改进,提出了新的安全环距设计原则。按安全环距原则设计,除可明显缓解终端效果随结构参数敏感变化的问题外,还可有效地提高在同样结构和工艺条件下所制成器件的额定电压。 展开更多
关键词 限制 安全环距 PN结 半导体物理
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有多个场限制环的平面器件的设计方法
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作者 丁辰 《上海半导体》 1992年第2期1-4,8,共5页
关键词 半导体器件 限制 平面器件
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用于脑部核磁共振图像分割的具有抗噪能力的BCFCM算法 被引量:3
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作者 栾方军 周佳鹏 曾子铭 《计算机科学》 CSCD 北大核心 2015年第10期311-315,320,共6页
脑部核磁共振成像(MRI)是脑疾病临床诊断的重要手段,而脑组织的准确分割则是其中一个重要的环节。然而MRI图像中普遍存在的噪声和偏移场给脑组织的准确分割造成了很大的困难。在MRI图像分割算法中,偏移场矫正模糊C-均值算法(BCFCM)在模... 脑部核磁共振成像(MRI)是脑疾病临床诊断的重要手段,而脑组织的准确分割则是其中一个重要的环节。然而MRI图像中普遍存在的噪声和偏移场给脑组织的准确分割造成了很大的困难。在MRI图像分割算法中,偏移场矫正模糊C-均值算法(BCFCM)在模糊C-均值聚类算法(FCM)的基础上增加了对偏移场的估计和空间信息的使用,可以很好地消除图像偏移场对分割造成的影响。但是BCFCM算法由于没有考虑到噪声对偏移场估计的影响,因此对高噪声图像的分割效果欠佳。针对MRI脑组织分割,在图像预处理过程中提出一种快速的分割方法来去除颅骨及其附属物。此外,提出基于BCFCM的改进算法,该改进算法在迭代过程中可以通过对噪声强度的估计来自适应地改变目标函数窗口的大小。同时,该算法引入高斯核函数对偏移场进行平滑处理,并通过阈值限制偏移场的估计值,以有效地避免偏移场的错误估计对分割结果的影响。实验结果表明,改进后的算法不仅可以有效准确地分割脑组织,而且具有较强的抗噪声和处理偏移场的能力。 展开更多
关键词 磁共振成像 偏移矫正模糊C-均值聚类 噪声估计 自适应 偏移限制
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韩国语连接词尾“-■”的多义性分析 被引量:3
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作者 赵新建 《解放军外国语学院学报》 CSSCI 北大核心 2012年第2期38-41,共4页
原子观、原型观、图式观和单义观这4种有关语法多义性的观点在韩国语多义语法形态研究中都有体现。本文运用用法公约和语法场限制相结合的方法,考察韩国语连接词尾"-"的多义性。首先分析"-"所有用法的可公约性,然... 原子观、原型观、图式观和单义观这4种有关语法多义性的观点在韩国语多义语法形态研究中都有体现。本文运用用法公约和语法场限制相结合的方法,考察韩国语连接词尾"-"的多义性。首先分析"-"所有用法的可公约性,然后通过语法场内部的对比限制,提取"-"的语义公约值。分析结果显示,"-"的用法可以公约为用于通用语体的转折义,表现出一种相对单义性。 展开更多
关键词 韩国语连接词尾 语法多义 语法限制 语义公约 相对单义性
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A Novel Polysilicon and Oxide Sandwich Deep Trench with Field Limiting Ring for RF Power Transistors
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作者 齐臣杰 傅军 +1 位作者 王军军 刘理天 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2004年第11期1398-1402,共5页
A vertical sandwich deep trench with a field limiting ring is proposed to improve the breakdown voltage of power devices and high voltage devices.Simulation result shows that nearly 100% breakdown voltage of the plane... A vertical sandwich deep trench with a field limiting ring is proposed to improve the breakdown voltage of power devices and high voltage devices.Simulation result shows that nearly 100% breakdown voltage of the plane junction can be realized. 展开更多
关键词 deep trench field limiting ring breakdown voltage
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基于可见光通信精确定位中接收端转动角度的二维研究
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作者 王巍 梁绣滟 王宁 《电工技术学报》 EI CSCD 北大核心 2015年第S1期30-34,共5页
提出可见光精确定位时视场角限制和灵敏度限制对定位精度的影响。结合移动设备的加速度传感器测得接收端在实际使用过程中的倾斜角度,使用二维定位算法计算进行精确定位。仿真结果证明提出的系统模型不仅使得定位精度不依赖于接收端的... 提出可见光精确定位时视场角限制和灵敏度限制对定位精度的影响。结合移动设备的加速度传感器测得接收端在实际使用过程中的倾斜角度,使用二维定位算法计算进行精确定位。仿真结果证明提出的系统模型不仅使得定位精度不依赖于接收端的指向且定位精度在特定的仿真环境下能达到厘米级。相较于传统的精确定位方法,提出的算法考虑了接收端转动角度,具有实用价值。 展开更多
关键词 可见光精确定位 限制 灵敏度限制 加速度传感器
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三种基因检测分型方法在耐碳青霉烯抗生素肺炎克雷伯菌基因分型中的应用对比观察 被引量:3
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作者 王凤平 朱梓年 +1 位作者 张霆 张拔山 《山东医药》 CAS 2018年第31期90-92,共3页
目的比较限制性内切酶联合脉冲场凝胶电泳(PFGE)、多位点可变数目串联重复序列分析(MLVA)和肠杆菌基因间重复序列PCR(ERIC-PCR)在耐碳青霉烯抗生素肺炎克雷伯菌基因分型中的应用情况。方法 20株耐碳青霉烯类抗生素的肺炎克雷伯菌,分别采... 目的比较限制性内切酶联合脉冲场凝胶电泳(PFGE)、多位点可变数目串联重复序列分析(MLVA)和肠杆菌基因间重复序列PCR(ERIC-PCR)在耐碳青霉烯抗生素肺炎克雷伯菌基因分型中的应用情况。方法 20株耐碳青霉烯类抗生素的肺炎克雷伯菌,分别采用PFGE、MLVA和ERIC-PCR法,对肺炎克雷伯菌基因进行扩增并分型,并用Bio Numerics软件测算各方法 Simpson差异指数(D值,D值越趋于1表示该方法分辨力越好)。结果20株菌株共分为18个PFGE型,其中2个带型包含2株菌,其余16个带型分别只包含1株菌,分别有两组两株菌具有相同的PFGE型别;17个MLVA型,其中3个型别分别包含2株菌,其余16个型别只包含1株菌,以差异位点≤2个位点作为构建MLVA群的标准,20株菌中构建出4个MLVA克隆群;14个ERIC型,其中中优势型、次优势型分别为5、3株,其余12个型别分别只包含1株菌。PFGE、MLVA和ERIC-PCR法对耐碳青霉烯抗生素的肺炎克雷伯菌的D值分别为0.989 5、0.984 2、0.931 6。结论 PFGE、MLVA和ERIC-PCR对耐碳青霉烯抗生素的肺炎克雷伯菌的分型效果均较好。 展开更多
关键词 肺炎克雷伯菌 耐碳青霉烯抗生素的肺炎克雷伯菌 限制性内切酶联合脉冲凝胶电泳 多位点可变数目串联重复序列分析 肠杆菌基因间重复序列
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控制还是放纵:自由诗的“十三不靠”和“戴着镣铐跳舞”
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作者 薛世昌 《西部文艺研究》 2022年第1期29-38,共10页
自由诗创作中普遍存在着措词随意、意象混搭的语言暴力现象,严重误解着“自由”之精神,肆意扩张着“自由”的边界,其语言反常而不合理,其诗歌形象互相之间缺乏“勾魂摄魄”的内在联系,其行文漠视“须就上方体势而行之”的上下文场域限制... 自由诗创作中普遍存在着措词随意、意象混搭的语言暴力现象,严重误解着“自由”之精神,肆意扩张着“自由”的边界,其语言反常而不合理,其诗歌形象互相之间缺乏“勾魂摄魄”的内在联系,其行文漠视“须就上方体势而行之”的上下文场域限制,这样的诗写违背着艺术表达的准确性原则,违背着诗歌创作意象组合的和谐性原则,也违背着言语表述的语境限制原则,而导致表达涣散、语言向心力缺乏、圆融贯通之美缺失。优秀的诗人往往会对普遍的律令明知故犯、绝地逆袭,这种尽显诗人胆识、勇于履险、诗思放逸的撼人诗作不绝于史,而诗歌的控制学也须“为中才立规矩,为天才留余地”,在约束那些放纵之语的同时,也要呵护那些“越轨”之作的锐气。 展开更多
关键词 自由诗 准确性 限制 向心力 控制论
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Predicting the Dielectric Strength of c-C_4F_8 and SF_6 Gas Mixtures by Monte Carlo Method 被引量:3
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作者 吴变桃 肖登明 《Journal of Shanghai Jiaotong university(Science)》 EI 2007年第1期121-124,共4页
An improved Monte Carlo method was used to simulate the motion of electrons in c-C4F8 and SF6 gas mixtures for pulsed townsend discharge. The electron swarm parameters such as effective ionization coefficient, -↑α a... An improved Monte Carlo method was used to simulate the motion of electrons in c-C4F8 and SF6 gas mixtures for pulsed townsend discharge. The electron swarm parameters such as effective ionization coefficient, -↑α and drift velocity over the E/N range from 280~700 Td(1Td=10^-21 V·m^2) were calculated by employing a set of cross sections available in literature. From the variation cure of -↑α with SF6 partial pressure p, the limiting field (E/N)lim of gas mixture at different gas content was determined. It is found that the limiting field of c-C4F8 and SF6 gas mixture is higher than that of pure SF6 at any SF6 mixture ratio. Simulation results show excellent agreement with experiment data available in previous literature. 展开更多
关键词 c-C4F8 and SF6 gas mixture Monte Carlo limiting field dielectric strength
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Controlling Quantum State Transfer in Spin Chain with Confined Field 被引量:1
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作者 CHEN Bing SONG Zhi 《Communications in Theoretical Physics》 SCIE CAS CSCD 2006年第4X期749-754,共6页
As a demonstration of the spectrum-parity matching condition (SPMC) for quantum state transfer, we investigate the propagation of single-magnon state in the Heisenberg chain in the confined external tangent magnetic... As a demonstration of the spectrum-parity matching condition (SPMC) for quantum state transfer, we investigate the propagation of single-magnon state in the Heisenberg chain in the confined external tangent magnetic field analytically and numerically. It shows that the initial Gaussian wave packet can be retrieved at the counterpart location near-perfectly over a longer distance if the dispersion relation of the system meets the SPMC approximately. 展开更多
关键词 quantum state transfer spin chain confined field
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论刑法教义学的立法批判功能 被引量:9
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作者 吴亚可 《南大法学》 CSSCI 2021年第1期49-63,共15页
关于“刑法教义学是否具有对刑法立法进行批判的功能”这一问题,当前刑法学界存在肯定说和否定说。其中,否定说建立在这一前提上:作为刑法教义学基本逻辑起点的刑法规范是合理正当的刑法规范。然而,该前提因不符合立法事实,从而导致否... 关于“刑法教义学是否具有对刑法立法进行批判的功能”这一问题,当前刑法学界存在肯定说和否定说。其中,否定说建立在这一前提上:作为刑法教义学基本逻辑起点的刑法规范是合理正当的刑法规范。然而,该前提因不符合立法事实,从而导致否定说不具有合理性。刑法教义学作为刑法的规范意义的发现方法,对刑法立法进行的批判主要表现在模糊性刑法规范、滞后性刑法规范和“漏洞”型刑法规范的意义发现过程中,即根据社会生活事实对三者的通常规范意义进行扬弃,从而实现其规范意义的明确化、发展性和填补。但是,刑法教义学的立法批判功能也是有场域限制的,即刑法教义学的司法面向性和实践导向性决定了刑法教义学批判不能否定现行有效的刑法规定,同时,刑法规范语言的文义边界框定了面向司法的刑法教义学批判的基本限度。 展开更多
关键词 刑法教义学 规范意义发现 刑法教义学批判 限制
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Continuous Quantum Nondemolition Measurements of a Particle in Electromagnetic and Gravitational Fields
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作者 ZHU Chun-Hua ZHA Chao-Zheng 《Communications in Theoretical Physics》 SCIE CAS CSCD 2005年第3X期455-458,共4页
The detection of a particle in electromagnetic plus gravitational fields is investigated. We obtain a set of quantum nondemolition variables. The continuous measurements of these nondemolition parameters are analyzed ... The detection of a particle in electromagnetic plus gravitational fields is investigated. We obtain a set of quantum nondemolition variables. The continuous measurements of these nondemolition parameters are analyzed in the framework of restricted path integral formalism. We manipulate the corresponding propagators, and deduce the probabilities associated with the possible measurement outputs. 展开更多
关键词 continuous quantum nondemolition measurements restricted path integral
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Rapid and Sensitive Identification of Horse and Donkey Meat in Iraqi Markets Using SSR and PCR-RFLP Based on Mitochondrial DNA Cytochrome B Gene 被引量:3
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作者 Talib Ahmed Jaayid 《Journal of Agricultural Science and Technology(A)》 2013年第11期896-903,共8页
This study was carried out at the Genetic Engineering Lab, College of Agriculture, University of Basrah. DNA was extracted from samples containing meat of commercial products in the Basrah markets. The products subjec... This study was carried out at the Genetic Engineering Lab, College of Agriculture, University of Basrah. DNA was extracted from samples containing meat of commercial products in the Basrah markets. The products subjected to analysis using polymerase chain reaction (PCR) with species specific repeat (SSR) and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) techniques based on the sequence of the mitochondrial DNA cytochrome b gene (mtDNA cyt b gene). Then digestion with the Alu l restriction enzyme to establish a differential diagnosis detects and discriminates between meat species and adulteration in the products. SSR primers were applied, has been detected amplification of the encoded gene product, generated 221 bp in some imported minced and canned meat samples. The results show that SSR analysis produced a pattern that allowed a direct identification of horse and donkey meats in some imported minced and canned meat samples (Hana, Monde and Bavaria). The amplified 359 bp gene of mtDNA cyt b gene from samples in different product was cut using Alu 1 restriction enzyme resulting in restriction fragment length polymorphism (RFLP). Alu 1 was used to distinguish between the animals meat that belong to the family or one species. The digestion of the PCR product showed differences between products. Where the fragment length generated were 74, 76 and 189 bp. It belonged to horse meat. The fraud was detected in Hana, Monde and Bavaria products available in Basrah markets showing the presence of horse meat in these products that labeled as beef meats 100%. This revealed mtDNA cyt b gene as highly conserved and consequently a good molecular marker for diagnostic studies. Thus, this technique can be applied to food authentication for the identification of different species of animals in food products. 展开更多
关键词 Polymerase chain reaction SSR RFLP farm animal meats identification adulteration.
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Damage, failure and stability control of evolutionary process caused by re-exploitation of the residual resources
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作者 Xiao-Jing FENG Dong DUAN +2 位作者 Qu-Zhen TIAN Kai WANG Li-Bin LIU 《Journal of Coal Science & Engineering(China)》 2013年第4期462-467,共6页
On the basis of considering the heterogeneity and using the finite element numerical simulation, this thesis investi- gates the damage of the roof and coal as well as the failure of evolutionary process during the re-... On the basis of considering the heterogeneity and using the finite element numerical simulation, this thesis investi- gates the damage of the roof and coal as well as the failure of evolutionary process during the re-exploitation of the residual coal. According to the analysis of the damage field, stress field and the failure process, it explores the damage evolution, stress distribution laws and the damage models. Besides, this thesis puts forward the idea of penetrating and establishing drilling steels aimed at solving the problem of wall carving and roof fall, meanwhile this suggestion accomplishes the successful appli- cation effect in the testing ground. This thesis demonstrates that the re-exploitation of the residual coal can be carried out and the safe production can be ensured by adopting some measures. What's more, the research result provides the theoretical and practical experience for the re-exploitation of the residual coal in the similar conditions. 展开更多
关键词 re-exploitation of residual resources fully mechanized exploitation of the long wall damage evolution control ofstability numerical simulation
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Transient response of carbon nanotube integrated circuits 被引量:2
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作者 Panpan Zhang Yingjun Yang Tian Pei Chenguang Qiu Li Ding Shibo Liang Zhiyong Zhang Lianmao Peng 《Nano Research》 SCIE EI CAS CSCD 2015年第3期1005-1016,共12页
The speed of frequency response of all published carbon nanotube (CNT) integrated circuits (ICs) is far from that predicted. The transient response of CNT ICs is explored systematically through the combination of ... The speed of frequency response of all published carbon nanotube (CNT) integrated circuits (ICs) is far from that predicted. The transient response of CNT ICs is explored systematically through the combination of experimental and simulation methods. Complementary field-effect-transistor (FET) based inverters were fabricated on a single semiconducting CNT, and the dynamic response measurement indicates that it can only work at an unexpectedly low speed, i.e. with a large propagation delay of 30 }_ts. Owing to the larger output resistance of CNT FETs, the existence of parasitic capacitances should induce much larger resistive-capacitive (RC) delay than that in Si ICs. Through detailed analysis combining simulation and experimental measurements, several kinds of parasitic capacitances dragging down the actual speed of CNT FET ICs are identified one by one, and each of them limits the speed at different levels through RC delay. It is found that the parasitic capacitance from the measurement system is the dominant one, and the large RC delay lowers the speed of CNT FETs logic circuits to only several kHz which is similar to the experimental results. Various optimized schemes are suggested and demonstrated to minimize the effect of parasitic capacitances, and thus improve the speed of CNT ICs. 展开更多
关键词 type keywordscarbon nanotube field-effect-transistors (CNTFETs) transient response parasitic capacitance propagation delay digital circuits
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Research on the transfers to Halo orbits from the view of invariant manifolds 被引量:4
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作者 XU Ming TAN Tian XU ShiJie 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2012年第4期671-683,共13页
This paper discusses the evolutions of invariant manifolds of Halo orbits by low-thrust and lunar gravity. The possibility of applying all these manifolds in designing low-thrust transfer, and the presence of single-i... This paper discusses the evolutions of invariant manifolds of Halo orbits by low-thrust and lunar gravity. The possibility of applying all these manifolds in designing low-thrust transfer, and the presence of single-impulse trajectories under lunar gravity are also explained. The relationship between invafiant manifolds and the altitude of the perigee is investigated using a Poincare map. Six types of single-impulse transfer trajectories are then attained from the geometry of the invariant manifolds. The evolutions of controlled manifolds are surveyed by the gradient law of Jacobi energy, and the following conclusions are drawn. First, the low thrust (acceleration or deceleration) near the libration point is very inefficient that the spacecraft free-flies along the invariant manifolds. The purpose is to increase its velocity and avoid stagnation near the libration point. Second, all con- trolled manifolds are captured because they lie inside the boundary of Eatlh's gravity trap in the configuration space. The evo- lutions of invariant manifolds under lunar gravity are indicated from the relationship between the lunar phasic angle and the altitude of the perigee. Third and last, most of the manifolds have preserved their topologies in the circular restricted three-body problem. However, the altitudes of the perigee of few manifolds are quite non-continuous, which can be used to generate single-impulse flyby trajectories. 展开更多
关键词 libration point Halo orbit transfer trajectory invariant manifolds low thrust lunar perturbation
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