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磁光盘道间距的相对周期测量法 被引量:3
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作者 程裕霞 裴先登 刘本喜 《华中理工大学学报》 CSCD 北大核心 2000年第6期86-88,共3页
论述了研制磁光盘机械特性测试系统时根据相同位移长度内的光栅信号和光道信号周期数以及光栅信号每mm周期数测量道间距的方法、原理及实现 ,提出了相对基线过零求周期数的方法 ,给出了测量结果 .
关键词 磁光盘 道间距 相对周期测量法 信道 机械特性
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非线性条件下编队卫星周期性相对运动条件 被引量:3
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作者 杏建军 李海阳 +1 位作者 唐国金 郗晓宁 《宇航学报》 EI CAS CSCD 北大核心 2006年第3期359-362,389,共5页
利用编队卫星机械能守恒原理,提出了非线性条件下求解编队卫星周期性相对运动条件的新方法,给出了非线性周期相对运动的初始条件。编队卫星相对距离较近时,利用非线性周期运动条件,可修正Hill方程的初始条件,抑制编队卫星的长期漂移。... 利用编队卫星机械能守恒原理,提出了非线性条件下求解编队卫星周期性相对运动条件的新方法,给出了非线性周期相对运动的初始条件。编队卫星相对距离较近时,利用非线性周期运动条件,可修正Hill方程的初始条件,抑制编队卫星的长期漂移。编队卫星相对距离较大,非线性因素不可忽略时,利用非线性周期运动条件,可找到不需消耗任何燃料的周期性相对运动轨道。最后的数值仿真结果验证了该方法的正确性。 展开更多
关键词 卫星编队 周期相对运动 初始条件 机械能守恒
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航天器相对运动建模及周期性相对运动求解 被引量:5
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作者 刘柔妮 陈杰 +1 位作者 孔祥龙 周世宏 《上海航天》 CSCD 2019年第1期101-108,共8页
面向航天器编队飞行的需求,对椭圆参考轨道航天器非线性周期相对运动条件进行研究,提出了确定椭圆参考轨道编队航天器非线性周期性相对运动条件的新方法。首先,考虑非线性、椭圆轨道等因素,通过哈密尔顿-雅可比(HJ)方程和正则摄动理论,... 面向航天器编队飞行的需求,对椭圆参考轨道航天器非线性周期相对运动条件进行研究,提出了确定椭圆参考轨道编队航天器非线性周期性相对运动条件的新方法。首先,考虑非线性、椭圆轨道等因素,通过哈密尔顿-雅可比(HJ)方程和正则摄动理论,推导了在任意非线性摄动下相对运动的模型和获得不需消耗任何燃料的周期性相对运动轨道的条件;然后,采用时域配点法,结合改进的列文伯格-马夸尔特(LM)法对周期性相对运动的初值进行求解;最后,设计数值仿真算例,利用上述条件,得到不消耗任何燃料的周期性绕飞轨道,由此验证了本文所提模型和方法的正确性。 展开更多
关键词 哈密尔顿-雅可比方程 正则摄动 周期相对运动 初始条件 非线性摄动
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振荡函数一致连续性研究 被引量:6
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作者 杨小远 王玮彬 +2 位作者 张立文 马建华 沈诚浩 《河南科学》 2010年第8期899-901,共3页
在研究判断函数的一致连续性时,发现当复合函数是振荡性函数时,它在定义域内的一致连续性很难通过传统的判别法进行判断.因此提出了振荡性函数的相对周期概念,并得出新的判别函数一致连续性的方法.
关键词 一致连续 振荡型周期函数 相对周期 相对周期判别法
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多元振荡函数一致连续性研究 被引量:3
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作者 杨小远 王玮彬 马建华 《河南科学》 2010年第9期1061-1064,共4页
通过引入刻画震荡函数频率的相对周期定义,提出一类多元振荡函数的一致连续性的判别方法,通过实际的例子说明该判别方法的有效性.丰富了多元函数一致连续问题的结论.
关键词 一致连续 多元振荡函数 相对周期 广义相对周期定理
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衍射光学元件设计参数对杂散光的影响(英文) 被引量:2
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作者 殷可为 黄智强 +1 位作者 林妩媚 邢廷文 《红外与激光工程》 EI CSCD 北大核心 2013年第11期3059-3064,共6页
衍射光学元件被广泛应用于激光光束整形领域中。然而,在实际测量中常常发现衍射效率实际的测量值与设计值存在较大的偏差,原因之一在于输出的焦斑主瓣以外会产生高级次衍射杂散光。文中从理论上推导了高级次衍射杂散光产生的原因并对具... 衍射光学元件被广泛应用于激光光束整形领域中。然而,在实际测量中常常发现衍射效率实际的测量值与设计值存在较大的偏差,原因之一在于输出的焦斑主瓣以外会产生高级次衍射杂散光。文中从理论上推导了高级次衍射杂散光产生的原因并对具有不同设计参数的衍射光学元件进行了仿真分析。通过研究,定义了一个新的参数,相对周期。它与光波波长成正比,与衍射光学元件的采样单元尺寸以及远场衍射角成反比。结果表明,衍射光学元件的衍射效率只是关于相对周期的函数,而与焦斑主瓣的具体形状无关。随着相对周期的增加,衍射效率随之增大。所以可通过适当选取远场衍射角和采样单元尺寸的参数以调整相对周期的大小,有效抑制高级次衍射杂散光。该参数在衍射元件的设计中具有重要的指导意义。 展开更多
关键词 衍射光学元件 光束整形 衍射效率 相对周期
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向量函数一致连续的判别方法研究
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作者 王玮彬 马建华 杨小远 《理论数学》 2012年第1期45-52,共8页
本文研究了向量函数的一致连续问题。提出了向量函数相对周期的概念,在此基础上,给出了向量函数一致收敛的判别方法,最后给出实际应用的例子,说明本文提出方法的有效性。
关键词 向量函数 一致连续 相对周期 比较判别法
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中美两国汇率波动与相对经济周期的联动性——基于频谱分析的研究 被引量:4
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作者 刘尧成 丁剑平 《上海经济研究》 CSSCI 北大核心 2012年第3期74-83,共10页
本文指出人民币兑美元实际汇率波动可能与中美两国间相对经济周期具有紧密的联动性,为此,本文首先构造了一个理论模型对两国间实际汇率波动与相对经济周期关联的存在性进行了论证,随后应用频谱分析技术对1994:Q1至2011:Q4人民币兑美元... 本文指出人民币兑美元实际汇率波动可能与中美两国间相对经济周期具有紧密的联动性,为此,本文首先构造了一个理论模型对两国间实际汇率波动与相对经济周期关联的存在性进行了论证,随后应用频谱分析技术对1994:Q1至2011:Q4人民币兑美元实际汇率波动与中美相对经济周期的联动性进行了实证检验。主要的结论有两个,一是在样本时段内中美相对经济周期领先于人民币兑美元实际汇率的波动,二是在4年左右一个波动周期的频域内二者的联动性最高。以上结论说明中美相对经济周期是人民币兑美元汇率波动的决定因素,而调整人民币兑美元汇率并不能改变中美两国经济的失衡关系。 展开更多
关键词 人民币兑美元汇率 相对经济周期 频谱分析
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椭圆参考轨道编队卫星非线性周期性相对运动条件 被引量:2
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作者 杏建军 唐国金 +2 位作者 郗晓宁 张翼 李海阳 《清华大学学报(自然科学版)》 EI CAS CSCD 北大核心 2006年第8期1462-1465,共4页
利用编队卫星机械能之差守恒,提出了确定椭圆参考轨道编队卫星非线性周期性相对运动条件的新方法。该方法不用求解非线性相对运动微分方程,只需解一个一元二次代数方程,就可给出任意偏心率和非线性条件下,两个具有明显物理意义的周期性... 利用编队卫星机械能之差守恒,提出了确定椭圆参考轨道编队卫星非线性周期性相对运动条件的新方法。该方法不用求解非线性相对运动微分方程,只需解一个一元二次代数方程,就可给出任意偏心率和非线性条件下,两个具有明显物理意义的周期性相对运动初始条件。利用这些条件,可找到不需消耗任何燃料的周期性相对运动轨道。最后的数值仿真结果验证了该方法和结论的正确性。 展开更多
关键词 卫星编队 周期相对运动 初始条件 机械能之差 非线性 椭圆参考轨道
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Asymmetry in the Strong-field Photodetachment of H- by Linearly Polarized Few-cycle Pulses
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作者 白丽华 刘宇恒 +2 位作者 崔婷婷 王燕 张惠芳 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2011年第2期141-144,I0003,共5页
Photodetachment of H- irradiated by linearly polarized few-cycle laser field is investigated by time-dependent SchrSdinger equation numerically. The photo-electron left-right asymmetry parameter as a function of carri... Photodetachment of H- irradiated by linearly polarized few-cycle laser field is investigated by time-dependent SchrSdinger equation numerically. The photo-electron left-right asymmetry parameter as a function of carrier-envelop (CE) phase of few-cycle pulses is attained. We confirm the asymmetry of photoelectron distribution in H- photodetachment and find that the maximal asymmetry parameter of H- is equal to that of H atom under the same conditions but the corresponding CE phases are quite different. Thus a CE phase shift appears. Compared to that of H atom and field free electron, the zero asymmetry CE phase shift is sensitively affected by Coulomb field. The Coulomb effect on the asymmetry of H- photodetachment mainly behaves in the CE phase shift of H- instead of the amplitude of asymmetry parameter curve. 展开更多
关键词 Asymmetry parameter PHOTODETACHMENT Carrier-envelop phase Few-cycle pulse H-
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基于构型控制的多平台协同轨迹规划
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作者 符俊 丁洪波 蔡洪 《飞行器测控学报》 2010年第6期13-19,共7页
编队卫星的整体机动需要充分考虑各成员之间的协同运动关系,同时到达和不分散/不碰撞是其应满足的约束条件。首先基于C-W方程和Lawden方程得出了参考轨道为圆轨道/椭圆轨道下的周期性相对运动条件,针对不同飞行任务要求(对应中心航天器... 编队卫星的整体机动需要充分考虑各成员之间的协同运动关系,同时到达和不分散/不碰撞是其应满足的约束条件。首先基于C-W方程和Lawden方程得出了参考轨道为圆轨道/椭圆轨道下的周期性相对运动条件,针对不同飞行任务要求(对应中心航天器不同转移轨道),提出了一种整星编队机动的规划策略。仿真结果表明,该规划方法实现简单,且能满足编队协同运动的约束条件。 展开更多
关键词 C-W方程 Lawden方程 协同运动 规划策略 周期相对运动
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欧元走低无伤大雅
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作者 王星桥 《中外经贸信息》 2000年第5期48-48,共1页
关键词 欧元 美元心理关口 相对周期前景 国际金融充机
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Laboratory Investigation of Disintegration Characteristics of Purple Mudstone under Different Hydrothermal Conditions 被引量:17
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作者 ZHANG Dan CHEN Anqiang LIU Gangcai 《Journal of Mountain Science》 SCIE CSCD 2012年第1期127-136,共10页
Disintegration of rock is one of the primary processes of soil formation and geomorphology and is affected considerably by water and heat.This study focused on the disintegration characteristics under laboratory condi... Disintegration of rock is one of the primary processes of soil formation and geomorphology and is affected considerably by water and heat.This study focused on the disintegration characteristics under laboratory conditions of typical purple mudstone from the Tuodian group of Jurassic red beds(J3t) in Tuodian Town,Shuangbai county,Yunnan Province of southern China.The fresh mudstone was subjected to alternating applications of water,heat and hydrothermal interaction during five treatments:wetting-drying(WD),saturation(ST),refrigeration-heating(RH),a combination of wetting-drying and refrigeration-heating(WDRH),and a combination of saturation and refrigeration-heating(STRH).Each treatment was run in twenty-four cycles.The results showed that there are three types of disintegration:collapsing disintegration,exfoliation disintegration and imperceptible disintegration.The cumulative disintegration rate(percentage of cumulative disintegrated mass to the initiative sample mass passed through a 2 mm sieve) produced a 'S'-shape function when related to treatment cycle time and closely fit a logistic model(R2 > 0.99).The rank order of the cumulative disintegration rate resulting from the five treatments was as the following:WDRH > STRH > ST > WD > RH.Because of alternating periods of moisture and dryness,WD caused the most disintegration,while RH alone resulted in imperceptible disintegration.Additionally,there was a negative correlation between the disintegration rate of each treatment cycle(percentage of disintegrated mass to the treated sample mass) and treatment cycle number.There was a positive correlation between this rate and temperature change under moist conditions,indicating that a change in temperature greatly accelerates the disintegration of parent rock when water was supplied. 展开更多
关键词 Physical weathering Mudstone Rock disintegration Hydrothermal interaction Water alternation Heat alternation
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Investigation Food Diet of Cobitis taenia in Talar River (Mazandaran Province)
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作者 Soheil Bahrebar 《Journal of Food Science and Engineering》 2012年第12期697-704,共8页
Perch sweeper fish with scientific name Cobitis taenia is one of the Cobitidae family. Since this kind of fish lives in clean waters and in the high areas of Talar River, it can be an index on water implution. This su... Perch sweeper fish with scientific name Cobitis taenia is one of the Cobitidae family. Since this kind of fish lives in clean waters and in the high areas of Talar River, it can be an index on water implution. This survey on the diet of this specimen is done on two stations (Kaselian and Tajoon) and shallow and high areas of Talar River in Mazandaran (Southern part of Caspian sea) and the duration of this survey is from October 2008 till September 2009. We should mention that fishing was just done by electro-shocker with voltage 300 V. And this fish after fishing is fixation in 10% formalin solution. So 410 perch sweeper fish were examined and the average of relatively length of gut (RLG) was 17.35 cm. The index of vacated intestine (VI) was calculated 43.35% for all samples. From intense of diet points of view (GSI), the most frequency of full intestines was considered in summer and spring. On the other hand, the smallness of relatively length of gut index (RLG 〈 1) shows that perch sweeper fish's diet manner is inclined to herbivority. In the examination of containing of digestive track, overally 10 kinds of foodstuff were known. Based on amount of this index, 2.67% Chironomidae is known as main bait in all sampling period. 展开更多
关键词 Perch sweeper fish (Cobitis taenia) DIET Mazandaran Talar River.
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Oscillating Flat FRW Dark Energy Dominated Cosmology from Periodic Functional Approach
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作者 EL-NABULSI Ahmad Rami 《Communications in Theoretical Physics》 SCIE CAS CSCD 2010年第7期16-20,共5页
I discuss the modification of Einstein's Theory of General Relativity based on a periodic functional approach. In this new approach, a corrected periodic gravitational coupling constant arises and plays the role of p... I discuss the modification of Einstein's Theory of General Relativity based on a periodic functional approach. In this new approach, a corrected periodic gravitational coupling constant arises and plays the role of periodic damping term acting on the theory. It is found that it is achievable to have an oscillating universe dominated by dark energy and expanding aceeleratedly in time. 展开更多
关键词 corrected gravitational coupling constant dark energy cosmological constant oscillating universe accelerated expansion
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Flank gland-secreted putative chemosignals pertaining to photoperiod,endocrine states,and sociosexual behavior in golden hamsters
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作者 Ying-Juan LIU Da-Wei WANG +2 位作者 Lixing SUN Jin-Hua ZHANG Jian-Xu ZHANG 《Current Zoology》 SCIE CAS CSCD 北大核心 2010年第6期800-812,共13页
Behavioral studies have shown that flank glands are involved in chemical communication in golden hamsters Mesocricetus auratus but little chemical analysis has been conducted on volatiles arising from these glands. Us... Behavioral studies have shown that flank glands are involved in chemical communication in golden hamsters Mesocricetus auratus but little chemical analysis has been conducted on volatiles arising from these glands. Using gas chromatography-mass spectrometry, we detected compounds from the flank glands of males, only eight of which were also produced in females. Based on these chemical data we performed a number of further experiments. By manipulating light we found that males exposed to short-photoperiods developed smaller flank glands than those exposed to long-photoperiods. Six flank gland volatiles reduced in relative abundance, which possibly coded for reproductive status of males of this seasonally breeding hamster species. Through dyadic encounters, we were able to induce the formation of dominant-subordinate relationships and show that two glandular compounds became high in relative abundance and may function as dominance pheromones. Castration eliminated all male-specific compounds resulting from flank glands, but bilateral ovariectomies only affected one compound in females. Once these ovariectomized females were treated with testosterone, their glandular compounds resembled those of males, suggesting these compounds are under the main control of androgen. Two female putative pheromones, tetradeeanoic acid and hexadecanoic acid, were used in binary choice tests and were both found to attract males over females. Applying a solution of these pheromone compounds to adult males also suppressed their agonistic behavior [Current Zoology 56 (6): 800-812, 2010]. 展开更多
关键词 Dominance Flank gland GONADECTOMY PHOTOPERIOD Putative pheromone Testosterone
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Life History of the Lenkoran Capoeta Capoeta Gracilis (Keyserling, 1981) in the Atrak River, Northern Iran
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作者 Rahman Patimar Abdol-Jalil Hajili Davaji Aisoltan Jorjani 《Journal of Life Sciences》 2011年第5期369-375,共7页
Within the wide distribution of Lenkoran in Iran, populations of the species inhabit variety of habitats. The authors hypothesized that each river may contribute to habitat-specific variation in life history of the fi... Within the wide distribution of Lenkoran in Iran, populations of the species inhabit variety of habitats. The authors hypothesized that each river may contribute to habitat-specific variation in life history of the fish. To test this, a total of 378 specimens of Capoeta capoeta gracilis caught in the Atrak river (northern Iran) from Dec. 2007 to Nov. 2008 were examined for life history attributes. The population has a 5-year life cycle. Weight-length relationship (WLR) was estimated as W = 0.0127TL28981 for males, W = 0.0083TL3998 for females and W = 0.0084TL3942 for the population, being allometric negative for males and positive for females and the population. The VBGF fit to back-calculated size at age data were: Lt = 22.11 (1-e-0.19(t+135)), Lt = 25.37 (1-e-0.18(t+125)) and Lt = 24.92 (1-e-018(1+122)) for males, females and sexes combined respectively. Sex ratio was significant from the parity, females dominated. The reproductive season, evaluated from GSI, extended from Apr. to July, with the highest peak in May for males and in Apr. for females. The absolute fecundity ranged between 458-5,743 eggs with a mean of 1,375.06 eggs. Fecundity relative to total weight fluctuated from 14.90 to 132.58, with a mean value of 48.79 eggs·g-1. The diameter of oocytes ranged from 0.53 to 2.40 mm with a mean value of 1.46. The life history patterns of C. c. gracilis in the considered population imply that the many population characteristics of this species in the river differ markedly from those of other rivers of its range distribution in northern Iran. Probably, respond to environmental characteristics to improve fitness locally is the more suitable choice for differentiated life history strategies of the species in the river. 展开更多
关键词 Capoeta capoeta gracilis age GROWTH REPRODUCTION Atrak river Iran.
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