排序方式: 共有141条查询结果,搜索用时 14 毫秒
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微弱谐波信号的灵敏检测具有重要的实际应用意义, 本文利用受控Chen系统来实现强噪声背景下的这种检测. 因动力系统可分解为慢变系统与快变系统的叠加, 这里用平均法对检测系统进行处理得到慢变系统, 并获取使系统由周期轨道突变为稳定平衡点的检测参数临界值. 通过调节检测参数, 观测系统状态变量的变化可判断待测信号是否存在. 仿真结果表明, 此方法可以准确检测出强噪声背景下的微弱谐波信号. 与目前其他基于混沌振子的检测方法相比, 该方案对噪声具有更强的免疫性, 而且可通过理论分析得出检测参数阈值的准确范围, 有利于在相关领域推广应用. 相似文献
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应用可调谐半导体激光吸收光谱(TDLAS)技术开放单光路短光程检测西林瓶内氧气浓度,因玻璃瓶壁造成入射光多次反射和透射,形成多光束干涉,严重影响信号波形和检测精度。本文提出了一种改变激光入射角度来抑制瓶壁光学干扰的方法,理论分析了入射角度对透射光强分布的影响,详细推导了使两相干光束叠加部分在接收端探测范围之外的入射角度计算公式,并根据现场参数得到理论最佳入射角度。对氧气浓度1%的样瓶进行多次测量,将二次谐波信号峰值的平均值作为信号,峰值的标准差作为噪声,以信噪比(signal to noise radio, SNR)最大作为系统入射角角度的优化指标,实验获得系统的实际最佳入射角度。与决定系数较高的入射角度进行浓度预测对比,交互验证后的最小二乘拟合结果显示:相关系数分别为0.995 9和0.988 9,前者相比后者提高了0.7%,预测的均方根误差(root mean square errors of prediction, RMSEP)分别是0.003 1和0.005 3,前者相比后者降低了41.5%,说明本文方法所确定的最佳入射角,能有效抑制玻璃瓶壁引起的多光束干涉影响,改善系统检测精度。 相似文献
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Chikun Ding 《International Journal of Theoretical Physics》2014,53(2):694-705
In the frame of Hamilton-Jacobi method, the back-reactions of the radiating particles together with the total entropy change of the whole system are investigated. The emission probability from this process is found to be equivalent to the null geodesic method. However its physical picture is more clear: the negative energy one of a virtual particle pair is absorbed by the black hole, resulting in the temperature, electric potential and angular velocity increase; then the black hole amount of heat, electric charge and angular momentum can spontaneously transfer to the positive energy particle; when obtaining enough energy, it can escape away to infinity, visible to distant observers. And this method can be applied to any sort of horizons and particles without a specific choice of (regular-across-the-horizon) coordinates. 相似文献
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A bipyrazolato-bridged tetra-palladium(II) cyclic complex, {[(dmbpy)Pd]2(μ-L)}·(PF6)4·2(C4H10O)·(H2O) ( μ-L=1,2-bis(3,5-dimethyl-pyrazol-4-yl)benzene), was synthesized and characterized by the 1H NMR, element analysis, and its single crystal structure was determined by X-ray diffraction method. It crystallizes in the Tetragonal space group P4/mbm with unit cell parameters: a=2.020 0(1) nm, b=2.020 0(1) nm, c=1.281 4(1) nm, and V=5.228 5(5) nm3, Z=2, R=0.047 8, wR=0.083 9. The crystal structure revealed that two [(dmbpy)Pd]2 moieties were bridged by two bipyrazolate ligands to form a tetra-palladium(II) cyclic complex. The Pd…Pd separation within the complex is 0.315 5(1) nm, indicat-ing weak interaction. CCDC: 645322. 相似文献
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Copper oxide particles with different morphology (flower-like, peach kernel-like, and dandelion-like) are prepared with hydrothermal method by adjusting chitosan ((C6H11NO4)n) concentration in aqueous mixed solutions of ammonia and Cu(NO3)2. Various morphologies of porous cupric oxide (CuO) particles are formed by agglomerated nanosheet primary particles and lead to different electrochemical performance of electrodes. The peach kernel-shaped CuO exhibits high reversible capacity and rate capability. The reversible capacity is 722.7 mAh g?1 at 0.1 C in the first cycle and 339 mAh g?1 after 50 cycles at 0.2, 0.5, 1.0, and 2.0 C ratio. The higher reversible capacities and good cycling performance are attributed to the larger specific surface area, leading to better contact between CuO and electrolyte. 相似文献
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An organic‐based monolith with long alkyl chain ligands was prepared by UV photo‐initiation using (a) 1‐octadecene as a functional monomer, (b) ethylene glycol dimethacrylate (EDMA) as the cross‐linking agent, (c) 1‐propanol, 1,4‐butanediol and dimethylformamide as triporogenic solvents, and (d) Irgacure 1800 as the initiator. The monoliths containing a high fraction of 1‐octadecene possessed a better total porosity, improved permeability, and result in faster separation. Similar monolithic capillary was quickly fabricated in 3 min by microwave irradiation using azobisisobutyronitrile as the thermal initiator. Conventional polyimide‐coated capillaries were used instead of expensive UV‐transparent capillaries in both methods. 相似文献
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