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基于光流平衡法的无人直升机视觉障碍回避 被引量:2
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作者 杨文凤 宋攀 谢强 《中国科技信息》 2014年第1期47-49,共3页
自主障碍检测与回避是无人直升机贴地飞行时保障其生存性的一项关键技术。鉴于此,研究利用机器视觉的原理,采用仿生学的光流避障方法,通过单目前视摄像机获取图像,解算出光流速度场,进而利用光流平衡法对无人直升机在虚拟三维场景下贴... 自主障碍检测与回避是无人直升机贴地飞行时保障其生存性的一项关键技术。鉴于此,研究利用机器视觉的原理,采用仿生学的光流避障方法,通过单目前视摄像机获取图像,解算出光流速度场,进而利用光流平衡法对无人直升机在虚拟三维场景下贴地飞行时的障碍回避进行了实时仿真。仿真结果表明基于光流平衡法的无人直升机障碍回避方法具有一定的可行性。 展开更多
关键词 贴地飞行 视觉制导 平衡 障碍回避
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基于平衡式阵列的光电传感太阳跟踪系统 被引量:2
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作者 黄彦智 何宁 赵佳庆 《桂林电子科技大学学报》 2015年第5期377-381,共5页
为了提高太阳能电池的能量转化效率,依据太阳运行规律和季节的变化特点,设计了一种光电跟踪和太阳轨道跟踪相结合的实时太阳跟踪系统。采用平衡式阵列光电传感与时钟计算组合方法,分析太阳运动轨迹与方位控制对阳光跟踪与能量转换效率... 为了提高太阳能电池的能量转化效率,依据太阳运行规律和季节的变化特点,设计了一种光电跟踪和太阳轨道跟踪相结合的实时太阳跟踪系统。采用平衡式阵列光电传感与时钟计算组合方法,分析太阳运动轨迹与方位控制对阳光跟踪与能量转换效率的影响,基于四元阵光电传感对太阳运动轨迹与方向变化的阳光跟踪光电控制系统原理,通过光照强弱与时钟计算太阳历史位置进行快速跟踪。实验结果表明,该系统能实现太阳位置的二维实时跟踪和太阳能电池姿态控制,在光强大范围变化条件下也可精确地跟踪,大大提高了太阳光的利用率。 展开更多
关键词 平衡电传感 太阳能 电池 跟踪 方位控制
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土壤-植物系统中光照与氮素的相互关系研究 被引量:33
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作者 曾希柏 侯光炯 +1 位作者 青长乐 谢德体 《生态学报》 CAS CSCD 北大核心 2000年第1期103-108,共6页
运用盆栽试验,以莴笋为材料,在人工气候箱内进行研究,其结果表明:光照强度的变化,不仅会引起莴笋生物量和养分吸收量的改变,而且也将导致土壤养分状况的差异。不同肥力的3种紫色土,其养分含量受光照强度变化影响的状况是,NH+4-N和NO-3-... 运用盆栽试验,以莴笋为材料,在人工气候箱内进行研究,其结果表明:光照强度的变化,不仅会引起莴笋生物量和养分吸收量的改变,而且也将导致土壤养分状况的差异。不同肥力的3种紫色土,其养分含量受光照强度变化影响的状况是,NH+4-N和NO-3-N的含量均以大眼泥土>沙土>石骨子土,而碱解氮含量的变化则以沙土>石骨子土>大眼泥土。光照强度的变化亦影响氮肥的施用效果,在试验光强(80~320μmol/m2·s)范围内,光照愈强时莴笋产量愈高、且其同时对氮肥的需要量也相应由0.213g/pot增加到0.38g/pot。本试验的结果,较为完整地阐述了光照强度的变化与土壤养分、作物营养以及施肥之间的相互关系。 展开更多
关键词 氮素 相互关系 土壤--植物系统 平衡
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光照对鄂东南2种落叶阔叶树种幼苗生长、光合特性和生物量分配的影响 被引量:29
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作者 杨莹 王传华 刘艳红 《生态学报》 CAS CSCD 北大核心 2010年第22期6082-6090,共9页
通过设置4个光照梯度(25%、12%、6%和3%自然光)模拟鄂东南低山丘陵地区落叶阔叶林林下的光环境,研究了2种耐荫性不同的树种幼苗--麻栎(Quercus acutissima)和化香(Platycarya strobilacea)不同光强下的存活率、光合特性、生长和生物量分... 通过设置4个光照梯度(25%、12%、6%和3%自然光)模拟鄂东南低山丘陵地区落叶阔叶林林下的光环境,研究了2种耐荫性不同的树种幼苗--麻栎(Quercus acutissima)和化香(Platycarya strobilacea)不同光强下的存活率、光合特性、生长和生物量分配,探讨了低光环境中耐荫性不同的树种幼苗维持自身碳平衡的机制和权衡"存活-生长"选择的生活史策略。结果表明:(1)低光下的2个树种幼苗的生长、光合特性和生物量分配具有显著性差异。(2)各个光照梯度下麻栎幼苗都生长良好,存活率保持在35%以上,而化香幼苗遭遇高的死亡率,80d后3%和6%自然光下的幼苗全部死亡;低光环境中麻栎幼苗比化香幼苗具有更大的表观光量子(AQY)和最大净光合效率(Pmax),更低的光补偿点(LCP)和暗呼吸效率(Rd),即耐荫性较强的麻栎幼苗比耐荫性较弱的化香幼苗具有更高的低光碳同化率和碳捕获能力。(3)2个树种幼苗的成活率与RGR呈负相关关系,各个光照梯度下耐荫性较弱的化香幼苗的相对生长率(RGR)显著高于耐荫性较强的麻栎幼苗,而两个树种幼苗的净同化率(NAR)无明显差异。相对于麻栎幼苗较高的根生物量比(RMR),化香幼苗将更多的生物量分配给叶部,因而具有较高的叶生物量比(LMR)、叶面积比(LAR)和比叶面积(SLA)。不同耐荫性的幼苗生长及生物量分配方式的差异是植物"存活-生长"权衡后的结果,耐荫性弱的化香幼苗具有较高的生长潜力和较弱的自我保护能力,而耐荫性强的麻栎幼苗具有更高的低光碳储量,能够维持更好的低光碳平衡,具有竞争优势。 展开更多
关键词 幼苗存活率 合特性 相对生长率 生物量分配 平衡
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影响飞机驾驶舱显示器背光源LED的效率和输出量的因素——LED为LCD屏幕在驾驶舱的应用带来了新的维度 被引量:3
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作者 Francis Nguyen 赵立晴 《现代显示》 2009年第7期10-14,共5页
飞机座舱内的信息显示需要更高的安全性和可靠性,如今LED为LCD背光源和航空驾驶舱指示器带来了新的光维度,随着技术进步,将继续增加LED的效率,使得LED在驾驶舱显示和发光中的作用继续扩张,帮助飞机安全飞行。
关键词 LED背 飞机座舱 光平衡
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光刻物镜光瞳极平衡性标定方法 被引量:8
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作者 芮大为 史振广 +1 位作者 袁文全 张巍 《中国激光》 EI CAS CSCD 北大核心 2014年第9期276-283,共8页
极平衡作为光刻物镜的一项重要指标,受到多种误差因素综合调制,因此有必要准确区分各种误差源的独立贡献量。提出了一种标定方法,将远心度误差所引入的调制效果进行了解耦,对极平衡指标进行了标定,并与质心标定方法进行对比研究。实现... 极平衡作为光刻物镜的一项重要指标,受到多种误差因素综合调制,因此有必要准确区分各种误差源的独立贡献量。提出了一种标定方法,将远心度误差所引入的调制效果进行了解耦,对极平衡指标进行了标定,并与质心标定方法进行对比研究。实现途径是以Matlab程序作为载体,调用Code V进行远心度运算,对LightTools的光瞳强度仿真结果进行重新定位,从而获取远心分离后的极平衡性指标。此外,设计了一个光刻物镜方案作为研究对象,对标定程序进行了仿真验证。结果表明,该标定方法可有效分离远心误差对极平衡的调制作用,程序执行效率较高。 展开更多
关键词 学设计 刻物镜 瞳极平衡 远心度
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Effects of N,P and K Fertilizers on Photosynthetic Characteristics of Mulberry 被引量:2
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作者 黄盖群 危玲 +6 位作者 佟万红 高辉 殷浩 刘刚 张烈 孔繁慧 罗春燕 《Agricultural Science & Technology》 CAS 2012年第12期2562-2568,共7页
[Objective] The aim was to research the effects of N, P and K fertilizers on photosynthetic characteristics of mulberry. [Method] In the test, Chuan 826, a va- riety of mulberry, was taken as an example to explore the... [Objective] The aim was to research the effects of N, P and K fertilizers on photosynthetic characteristics of mulberry. [Method] In the test, Chuan 826, a va- riety of mulberry, was taken as an example to explore the relationships of chloro- phyll content, leaf area index, net photosynthetic rate, stomatal conductance of leaf, CO2 concentration of cells in leaves and transpiration rate with N, P and K fertilizers at different quantities. [Result] N, P and K fertilizers at different quantities have ef- fects on photosynthetic indices. In detail, N, P and K fertilizer at appropriate quanti- ties enhanced LAI, Chla+b, Pn, Cond and Tr, Ci of mulberry leaves in control group without fertilizers was significantly higher than that in treatment groups. N, P and K at proper quantities (N at 600 kg/hm2, P at 210 kg/hm2 and K at 300 kg/hm2) would keep functional leaves well and higher photosynthetic period for a long term. [Conclusion] The research explored adjustment of photosynthetic characteristics and differ- ent treatments on photosynthesis of mulberry, providing reference for construction of excellent and highly-qualified mulberry garden. 展开更多
关键词 MULBERRY Balanced fertilization Photosynthetic characteristics
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高温超导晶界结型红外探测器工作原理 被引量:5
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作者 周方桥 郝建华 +3 位作者 易新建 赵兴荣 孙汉东 李再光 《红外与毫米波学报》 SCIE EI CAS CSCD 北大核心 1993年第6期447-451,共5页
提出了高温超导晶界结型红外探测器在液氮温区可能同时存在测辐射热和光致非平衡两种效应的工作原理,给出了两种效应的响应率计算式,并在实验上研制了性能指标较高的YBa_2Cu_3O_(7-x)红外探测器。
关键词 高温超导体 测辐射热 致非平衡 超导红外探测器 晶界结构 YBa2Cu3O7-x超导薄膜红外探测器
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Functional Equilibrium Between Photosynthetic and Above-ground Nonphotosynthetic Structures of Plants: Evidence from a Pruning Experiment with Three Subtropical Tree Species 被引量:4
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作者 曾波 《Acta Botanica Sinica》 CSCD 2003年第2期152-157,共6页
It is well known that plants have functional equilibrium between their above-ground parts (shoots) and below-ground parts (roots), but whether the above-ground parts of plants have functional equilibrium between their... It is well known that plants have functional equilibrium between their above-ground parts (shoots) and below-ground parts (roots), but whether the above-ground parts of plants have functional equilibrium between their photosynthetic structures (leaves) and non-photosynthetic structures (branches and stem) is unknown. The purpose of this study is to test the hypotheses that: (1) the above-ground parts of plants have functional equilibriums between their photosynthetic structures and non-photosynthetic structures; (2) the maintenance of the equilibriums is guaranteed by the alteration of biomass partitioning to photosynthetic and non-photosynthetic structures. To test these hypotheses, a pruning experiment with four pruning intensities (0%, 20%, 50%, and 70%) were carried out with three subtropical Chinese tree species ( Ficus microcarpa, Ficus virens, Cinnamomum camphora). Pruning treatments were conducted in two successive years. The results were in conformity with the hypothesis, i.e. above-ground parts of trees had functional equilibriums between photosynthetic and non-photosynthetic structures. Pruning decreased instantaneously the mass ratios of photosynthetic structures to non-photosynthetic structures (P/NP) of all three tree species, the reduction in P/NP was strengthened with pruning intensity. However, one year after pruning, the P/NP of all pruned trees increased and were not smaller than those of unpruned trees. In agreement with the expectation, the biomass partitioning of pruned trees was altered, more newly produced above-ground biomass was partitioned to leaf growth and less to branch and stem growth, thus enabled the damaged trees to restore their functional equilibrium between photosynthetic and non-photosynthetic structures. It is clear that the maintenance of functional equilibrium between photosynthetic and non-photosynthetic structures guaranteed by the alteration of biomass partitioning provides plants a good strategy to resist external disturbance and damage. 展开更多
关键词 biomass partitioning functional equilibrium non-photosynthetic structures photosynthetic structures tree
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Theoretical analysis of ultra-short pulsed laser ablation of SiO_2 material based on a Coulomb explosion model
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作者 林晓辉 任维松 《Journal of Southeast University(English Edition)》 EI CAS 2011年第3期261-265,共5页
Based on the kinetic theoretical Vlasov-Poisson equation, a surface Coulomb explosion model of SiO2 material induced by ultra-short pulsed laser radiation is established. The non-equilibrium free electron distribution... Based on the kinetic theoretical Vlasov-Poisson equation, a surface Coulomb explosion model of SiO2 material induced by ultra-short pulsed laser radiation is established. The non-equilibrium free electron distribution resulting from the two mechanisms of multi-photon ionization and avalanche ionization is computed. A quantitative analysis is given to describe the Coulomb explosion induced by the self-consistent electric field, and the impact of the parameters of laser pulses on the surface ablation is also discussed. The results show that the electron relaxation time is not constant, but it is related to the microscopic state of the electrons, so the relaxation time approximation is not available on the femtosecond time scale. The ablation depths computed by the theoretical model are in good agreement with the experimental results in the range of pulse durations from 0 to 1 ps. 展开更多
关键词 ultra-short pulsed laser Coulomb explosion nonequilibrium distribution material ablation
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水田半旱式自然免耕是稻区农业腾飞的重要措施
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作者 李映强 《南方农村》 1999年第3期45-48,共4页
自然免耕是著名土壤学家侯光炯教授运用土壤肥力的生物热力学观点,模拟自然土高肥力机制而获得的能普遍高产的特殊耕作技术,是“土生万物,地力常新”的奥妙所在,近年来已在我国南方稻区得到了较大面积的推广应用。 众所周知,当生长繁茂... 自然免耕是著名土壤学家侯光炯教授运用土壤肥力的生物热力学观点,模拟自然土高肥力机制而获得的能普遍高产的特殊耕作技术,是“土生万物,地力常新”的奥妙所在,近年来已在我国南方稻区得到了较大面积的推广应用。 众所周知,当生长繁茂的自然植被一旦遭到破坏,使自然土开垦为农业土时,地面覆盖率大大下降,土壤水热条件发生明显变化,有机物质迅速矿化分解,水土流失加剧,土壤水分蒸发损失严重,致使土壤由湿变干,由干变硬,由硬变板,由板生裂,于是精耕细作、灌溉、施肥就成为人们维持土壤肥力所必须采取的手段。 展开更多
关键词 自然免耕 半旱式 维持土壤肥力 重要措施 冬水田 连续免耕 平衡 自然土 水稻 西南农业大学学报
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三星AnyCall G80E拍照手机挑战相机
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《数字生活》 2008年第3期46-46,共1页
搭载顶级摄影性能的三星AnyCall G808E来了!这部使用3倍光学变焦镜头的500万像素旗舰,具备先进的脸部追踪对焦、动态测光平衡和13种智慧场景,由内而外,G808E都有挑战数码相机的实力。
关键词 手机 数码相机 光平衡 拍照 变焦镜头 自动对焦 挑战 学镜头 像素 追踪
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Spectral Shift of π→π^* Transition for p-Nitroaniline Based on a New Expression of Nonequilibrium Solvation Energy
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作者 季健 任海生 +1 位作者 马建毅 李象远 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2014年第2期181-188,I0003,I0004,共10页
According to the nonequilibrium solvation theory studies, a constrained equilibrium principle is introduced and applied to the derivations of the nonequilibrium solvation energy, and a reasonable expression of the spe... According to the nonequilibrium solvation theory studies, a constrained equilibrium principle is introduced and applied to the derivations of the nonequilibrium solvation energy, and a reasonable expression of the spectral shift of the electronic absorption spectra is deduced. Furthermore, the lowest transition of p-nitroaniline (pNA) in water is investigated by time-dependent density functional theory method. In addition, the details of excited state properties of pNA are discussed. Using our novel expression of the spectral shift, the value of -0.99 eV is obtained for π→π^* transition in water, which is in good agreement with the available experimental result of -0.98 eV. 展开更多
关键词 Nonequilibrium solvation theory Spectral shift Solvent reorganization energy Constrained equilibrium
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A MICROPAYMENT SCHEME BASED ON WEIGHTED MULTI-DIMENSIONAL HASH CHAIN 被引量:2
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作者 Liu Yining Hu Lei Liu Heguo 《Journal of Electronics(China)》 2006年第5期791-794,共4页
Hash chain and its generalization—Multi-Dimensional Hash Chain (MDHC) have been widely used in the design of micropayment due to its simplicity and efficiency. In this letter, a more efficient variant of MDHC, called... Hash chain and its generalization—Multi-Dimensional Hash Chain (MDHC) have been widely used in the design of micropayment due to its simplicity and efficiency. In this letter, a more efficient variant of MDHC, called WMDHC, which endows in the structure of MDHC a weight value for each hash value through a well-defined mapping, is proposed. The average hash operation number of WMDHC is log(2 m / t ),which is better than log( m )of MDHC when the parameter t is typically suggested as t = 7. 展开更多
关键词 Micropayment Multi-Dimensional flash Chain (MDHC) Hamming weight
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The Equilibrium Range of Wind Wave Spectra: an Explanation Based on White Noise 被引量:1
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作者 DAI Dejun WANG Wei +1 位作者 QIAO Fangli YUAN Yeli 《Journal of Ocean University of China》 SCIE CAS 2007年第4期345-348,共4页
Laboratory experiments and field observations show that the equilibrium range of wind wave spectra presents a – 4 power law when it is scaled properly. This feature has been attributed to energy balance in spectral s... Laboratory experiments and field observations show that the equilibrium range of wind wave spectra presents a – 4 power law when it is scaled properly. This feature has been attributed to energy balance in spectral space by many researchers. In this paper we point out that white noise on an oscillation system can also lead to a similar inverse power law in the corresponding displacement spectrum, implying that the – 4 power law for the equilibrium range of wind wave spectra may probably only reflect the randomicity of the wind waves rather than any other dynamical processes in physical space. This explanation may shed light on the mechanism of other physical processes with spectra also showing an inverse power law, such as isotropic turbulence, internal waves, etc. 展开更多
关键词 wind wave spectrum equilibrium range -4 power law white noise
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Direct Observation of Singletππ*and nπ*Equilibrium State in 2-Amino-1,3,5-triazine Solution
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作者 Xiuhua Li Xueli Wang +3 位作者 Meng Lv Zhongneng Zhou Haifeng Pan Jinquan Chen 《Chinese Journal of Chemical Physics》 SCIE EI CAS CSCD 2022年第5期747-753,I0004-I0010,I0011,共15页
1,3,5-Triazine molecules represent a class of molecules that may have been prebiotic information carriers in a primordial soup in early Earth and their excited state dynamics has received attention in recent years.In ... 1,3,5-Triazine molecules represent a class of molecules that may have been prebiotic information carriers in a primordial soup in early Earth and their excited state dynamics has received attention in recent years.In our previous study,one component with lifetime longer than100 ps was discovered in 2-amino-1,3,5-trainzine(2-AT),but its nature has not been revealed.In this study,excited state dynamics of 2-AT is studied in different solvents by using femtosecond time-resolved transient absorption and fluorescence upconversion spectroscopy.Interestingly,an equilibrium state consisting of the brightππ^(*)and dark nπ^(*)states in 2-AT is directly observed in aqueous solution and its dynamics is solvent sensitive.The whole picture of the excited state deactivation mechanism of 2-AT is proposed based on our spectroscopy results. 展开更多
关键词 Ultrafast spectroscopy Equilibrium state Solvent sensitive kinetics 1 3 5-Triazine
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Cavity Ring Down Laser Absorption Spectroscopy of Nil
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作者 Tong-mei Ma Ling Li +2 位作者 Joanne Wing Har Leung Allan Shi Chung Cheung 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2009年第6期611-614,J0002,共5页
The absorption spectrum of NiI between 445 and 510 nm has been investigated using the technique of laser vaporization/reaction with free jet expansion and cavity ring down laser absorption spectroscopy. Two new transi... The absorption spectrum of NiI between 445 and 510 nm has been investigated using the technique of laser vaporization/reaction with free jet expansion and cavity ring down laser absorption spectroscopy. Two new transitions namely,[21.3]^2△5/2-X^2△5/2 and [21.9]^2Ⅱ3/2-X^2△5/2 systems were identified and studied. Spectra of both ^58NiI and ^60NiI isotopic molecules were observed. Equilibrium molecular constants for both electronic states are reported and the equilibrium bond length for the [21.3]^2△5/2 state and the[21.9]^2Ⅱ3/2 state was respectively determined to be 2.431 and 2.481 A. 展开更多
关键词 Nickel monoiodide Cavity ring down spectrum electronic transition
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Proposal of Realization Restricted Quantum Game with Linear Optic Method
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作者 ZHAO Hai-Jun PANG Xi-Ming 《Communications in Theoretical Physics》 SCIE CAS CSCD 2006年第1期75-78,共4页
We present a quantum game with the restricted strategic space and its realization with linear optical system, which can be played by two players who are separated remotely. This game can also be realized on any other ... We present a quantum game with the restricted strategic space and its realization with linear optical system, which can be played by two players who are separated remotely. This game can also be realized on any other quantum computers. We find that the constraint brings some interesting properties that are useful for making game models. 展开更多
关键词 quantum game RESTRICTION EQUILIBRIUM linear optic
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Load Balancing in WDM Optical Networks with and without Wavelength-Continuity Constraints
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作者 刘逢清 曾庆济 +2 位作者 杨旭东 朱栩 肖石林 《Journal of Shanghai Jiaotong university(Science)》 EI 2003年第1期29-34,共6页
In practical optical networks, there is often the same number of wavelengths in a fiber. But if it is not carefully designed, there will be much difference in link load among different fibers, and unnecessary waveleng... In practical optical networks, there is often the same number of wavelengths in a fiber. But if it is not carefully designed, there will be much difference in link load among different fibers, and unnecessary wavelengths will be needed. This paper investigated this load balancing issues to minimize the wavelength requirements. Both Integer Linear Programming (ILP) and heuristic algorithms were presented to solve such a problem in WDM optical networks with or without wavelength continuity constraints. 展开更多
关键词 load balancing WDM optical networks wavelength continuity constraints
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Basis Set Extrapolation for the High Resolution Spectroscopy
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作者 Kiran Sankar Maiti Christoph Scheurer 《Journal of Chemistry and Chemical Engineering》 2013年第11期1100-1110,共11页
Valence and all electron correlation energies of a large set of atoms and molecules with structural motifs from amino acids and peptides at their equilibrium as well as non-equilibrium geometries are calculated at the... Valence and all electron correlation energies of a large set of atoms and molecules with structural motifs from amino acids and peptides at their equilibrium as well as non-equilibrium geometries are calculated at the levels of MP2, RI-MP2, and CCSD (T) with Dunnings sequential correlation consistent basis sets. A two point basis set extrapolation scheme for correlation energies to the complete basis set limit based on only DZ (double-zeta) and TZ (triple-zeta) results is presented and analyzed. We show that this basis set extrapolation scheme reduces the computational cost by two to three orders of magnitude to obtain the same accuracy as simpler extrapolations from higher order basis set computations. 展开更多
关键词 Basis set extrapolation complete basis set limit correlation energy.
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