基于光纤振动安全预警系统的振源识别算法研究

光纤振动预警系统可自动采集周边振动信号,面对大量复杂的振动信号,如何准确识别目标振源是系统研究的难点。针对光纤振动安全预警系统采集到的振动信号进行属性特征分析,建立相应的特征模型,并建立振源属性特征模型,包括识别下雨振源的能量信息熵模型,以及区分机械施工和车辆经过振源的基频稳定性模型等。通过振源识别算法,提高了振源类型识别的准确性。测试结果表明,特征模型的设计和选择合理,识别准确率高。     

35MeV/u 40 Ar+197 Au反应中热核的碎裂密度

许多提取核反应过程中熵产生的方法只适用于高能核反应过程 ,而约化d的产额方法可以用于较低能量的重离子核反应中 .对于 3 5MeV/u40 Ar+ 197Au的核反应过程 ,利用这种方法所得的熵和约化带电粒子多重性提取的熵结果一致 .对于后角热核发射体系 ,实验提取的核温度为 ( 4.7± 1 .2 )MeV ,熵为S/A =2 .5± 0 .5,根据实验提取的熵和核温度可以确定其碎裂密度小于 0 .1 ρ0     

35MeV/u~(40)Ar ~(197)Au中的熵产生

根据量子统计模型 (QSM )的计算分析 ,找到了一个提取核反应过程中熵产生的新的可观测量 .核反应过程中约化d的产额d/ (d t 3 He 4 He)和熵有单调的函数关系 ,并且和体系的碎裂密度 (ρ/ ρ0 )及体系的N/Z都无关 ,可以作为提取核反应过程中熵产生的一个观测量 .和目前已经有的其他方法相比 ,约化d产额这一提取熵方法可以用于较低能量的重离子核反应中 ,并且数据处理分析简单 .对于 35MeV/u4 0 Ar 197Au的核反应过程所提取的熵和利用约化带电粒子多重性提取的熵结果一致 .结合后角类靶热核发射体系实验提取的同位素核温度为 4 7±1 2MeV及S/A =2 5± 0 5 ,根据熵和核温度的关联关系 ,可以确定其Breakup密度接近但小于 0 1(ρ/ ρ0 )     

STATISTICAL ENTROPIES OF THE TAUB－NUT/BOLT AdS SPACES FROM THE HORIZON CONFORMAL FIELD THEORY

The covariant phase technique is used to compute the constraint algebra of the four-dimensional space-times which are asymptotic to anti-de Sitter (AdS), such as the planar Taub－NUT AdS and Taub－bolt AdS spaces, and the hyperbolic Taub－bolt AdS space. The standard Virasoro subalgebrae with corresponding central charges for these objects are constructed and the resulting densities of states yield the expected Bekenstein－Hawking entropies.     

LARGE MAGNETIC ENTROPY CHANGE NEAR CHARGE-ORDERED TRANSITION TEMPERATURE IN PEROVSKITE-TYPE MANGANITE

The magnetocaloric effect in polycrystalline of Pr_1-xSr_xMnO₃ (x=0.33, 0.43, 0.50) has been investigated. A large magnetic entropy change (7.1J/kgK) was discovered in Pr_0.5Sr_0.5MnO₃ under a low magnetic field of 1T at charge-ordered state transition temperature (161K). The physical mechanism is related to a drastic magnetization change at a temperature where the field-induced magnetic, electron and structural phase transitions occur (from the antiferromagnetic charge-ordered state to the ferromagnetic charge-disordered state).     

Magnetic entropy change in GdCo13−xSix intermetallic compounds

The magnetic entropy change in GdCo_13−xSi_x (x=3.8, 4, 4.1, and 4.2) intermetallic compounds has been investigated by means of magnetic measurements in the vicinity of their Curie temperature. It was found that the magnetic ordering temperatures decrease from 60 K at x=3.8 to 28 K for x=4.2. The magnetic entropy change is calculated from isothermal magnetization versus magnetic field at various temperatures using the Maxwell relation. As a result, the maximum magnetic entropy changes of the investigated compounds, at their Curie temperatures, decrease from 11.5 J/kg K for x=4.2 to 6.86 J/kg K for x=3.8 in a field change of 0-3 T, whereas it decreases from 5.13 J/kg K for x=4.2 to 2.60 J/kg K for x=3.8 in a field change of 0-1 T. Moreover, the maximum value of the magnetic entropy change obtained at a higher field for GdCo_13−xSi_x with x=4 (23.75 J/kg K at 5 T) is comparable to that of various types of compounds with a cubic NaZn₁₃-type structure. Finally, the maximum of the magnetic entropy change is found to decrease with increasing Si content.     

The Tunneling Radiation Characteristics of Kerr-Newman de Sitter Black Hole

The strictly thermal spectrum in dragging coordinate system and the tunneling radiation characteristics of stationary axisymmetry Kerr-Newman de Sitter black hole is studied. The result shows that the tunneling rates at the event and cosmological horizon are related to the change of Bekenstein-Hawking entropy and that the factual radiation spectrum is not strictly pure thermal. Thus an exact correction to the Hawking thermal spectrum is present.     

Quantum Mutual Entropy for a Multilevel Atom Interacting with a Cavity Field

We derive an explicit formula for the quantum mutual entropy as a measure of the total correlations in a multi-level atom interacting with a cavity field. We describe its theoretical basis and discuss its practical relevance. The effect of the number of levels involved on the quantum mutual entropy is demonstrated via examples of three-, four- and five-level atom. Numerical calculations under current experimental conditions are performed and it is found that the number of levels present changes the general features of the correlations dramatically. PACS numbers: 32.80.−t, 42.50.Ct, 03.65.Ud, 03.65.Yz.     

Nonuniform sampling and maximum entropy reconstruction applied to the accurate measurement of residual dipolar couplings

Residual dipolar couplings (RDC) provide important global restraints for accurate structure determination by NMR. We show that nonuniform sampling in combination with maximum entropy reconstruction (MaxEnt) is a promising strategy for accelerating and potentially enhancing the acquisition of RDC spectra. Using MaxEnt-processed spectra of nonuniformly sampled data sets that are reduced up to one fifth relative to uniform sampling, accurate 13C'-13Calpha RDCs can be obtained that agree with an RMS of 0.67 Hz with those derived from uniformly sampled, Fourier transformed spectra. While confirming that frequency errors in MaxEnt spectra are very slight, an unexpected class of systematic errors was found to occur in the 6th significant figure of 13C' chemical shifts of doublets obtained by MaxEnt reconstruction. We show that this error stems from slight line shape perturbations and predict it should be encountered in other nonlinear spectral estimation algorithms. In the case of MaxEnt reconstruction, the error can easily be rendered systematic by straightforward optimization of MaxEnt reconstruction parameters and self-cancels in obtaining RDCs from nonuniformly sampled, MaxEnt reconstructed spectra.