A BaF2 crystal array for high energy γ-ray measurements

We shall discuss about the scientific motivation and construction of a 7×7 BaF₂ crystal array at Variable Energy Cyclotron Centre, Calcutta. This detector would be used to measure high energy γ-ray photons from GDR decay and proton-neutron bremsstrahlung reactions at the present 88″ cyclotron and upcoming superconducting cyclotron at VECC, Calcutta. This detector can also be used to measure photons from quark-gluon plasma at the relativistic heavy ion collider (RHIC) in USA.     

储粮害虫声信号的检测和应用

与传统的储粮害虫检测方法相比,害虫的声测报技术作为一种快速、实用的新方法,正日益受到重视,近年来,这一领域在微电子设备及计算机技术的推动下,取得了很大进展,已由最初在小容器谷物样品中钻蛀为害粮粒害虫声音的技术,发展到目前实仓多点监测储糖害虫声音的微机监控系统,实现了对储糖害虫侵害程度的量化,通过声信号识别害虫种类方面的工作也在进一步的研究中,文章综述了储糖害虫声测报领域的发展历程,最新进展及存在问题。     

The First Principle Formula of the Relativistic Heat Conductivity of Coulomb Electronic Plasmas

Making use of the relativistic BBGKY technique,the relativistic generalization of Landau collision integral is botained.Furthermore,we calculate the relativistic hydrodynamic modes up to the second order in the hydrodynamic wave number.Combining Resibois‘ method,we present the first principle formula of the relativistic heat conductivity of Coulumb electronic plasmas for low-order corrections.     

加性噪声对激光一级相变类比的影响

从单模激光场的增益－噪声模型出发,导出了激光场定态强度分布函数,研究了定态分布函数的极值点随加性噪声、乘性噪声和注入信号的变化情况。结果表明,乘性噪声是使激光系统出现一级相变类比的关键因素,注入信号使相变行为减弱,而加性噪声却使得定态分布中极值点的数量和位置出现来回跳跃式变化。     

含有注入信号的双向环形激光场中的驱动效应

用含有背散射和饱和效应的双模激光场的理论模型讨论了背散射和外加注入信号对环形激光场的统计性质的影响。结果表明,背散射可以抑制系统的涨落。对于均匀展宽的双向环形激光场,注入信号可以将其中的弱模光场由非相干光驱动成为相干光,而对于非均匀展宽的环形激光场则没有这种驱动效应。进一步研究发现,这种驱动效应与注入信号的强弱及两模式光场的抽运参量差异△α有关。     

Non-reciprocal transmission via phase conjugation in multimode optical fibres

We demonstrate phase conjugate correction of modal distortion of a single mode beam on double-passing a passive highly multimode fibre. Phase conjugation is achieved in a self-pumped photorefractive BaTiO₃ crystal which conjugates only the e-polarised input component. We show that only a small fraction of the multimode fibre output is required to faithfully conjugate the single mode input beam. This technique enables the demonstration of a novel non-reciprocal transmission device, which for example has immediate application in gain-grating holographic resonator designs with multimode fibres as the active gain medium.     

The DFS-heuristic for orthogonal graph drawing

In this paper, we present a new heuristic for orthogonal graph drawings, which creates drawings by performing a depth-first search and placing the nodes in the order they are encountered. This DFS-heuristic works for graphs with arbitrarily high degrees, and particularly well for graphs with maximum degree 3. It yields drawings with at most one bend per edge, and a total number of m−n+1 bends for a graph with n nodes and m edges; this improves significantly on the best previous bound of m−2 bends.     

The Bifurcation of the Equatorial Periodic Orbit of the Planar Polynomial Vector Fields

In this paper, we have obtained the necessary and sufficient condition for the set of points at infinity on the plane R ² to be a periodic orbit which is called an equatorial periodic orbit of a planar vector field X(x), and the formulae about the multiplicity of the equatorial periodic orbit of X(x). We have also proved that the main result of [9] is erroneous with regard to the formulae. This work is supported by the NSF of China     

The Study of Full Light Speech Signal Collection System

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EDFA增益谱的精确测量

本文设计一种精确测量EDFA增益谱方法,按照这种方法,不需要考虑EDFA的内部结构,使用较小功率的宽光谱光源和任意波长的激光器,能够较简便精确测量EDFA小信号增益.