Er^3＋掺杂玻璃的1．5μm发射光谱及其带宽

用高温熔融法制备了Er^3 掺杂的氧化物玻璃，研究了Er^3 在11～300K温度范围内对应于^4I13/2→^4I15/2跃迁的1．5μm发射光谱，将^4I13/2多重态中的高能态和最低能态向基态跃迁发射的光谱成分从测量的发射光谱中分离开来，讨论了光谱成分对1．5μm发射带宽的影响。提出了等效四能级模型，并用此模型解释了Er^3 ^4I13/2→^4I15/2辐射跃迁的线形及其变温特性。分析表明，提高^4I13/2多重态中高能态的辐射跃迁几率是获得室温下宽带1．5μm发射的关键。最后，根据Mc Cumber理论，利用吸收光谱变换得到了与测量一致的发射光谱形状及相应的受激发射截面。     

Processing and characterisation of low cost Balistid fish Sufflamen capistratus liver oil for edible purpose

The physico-chemical properties of liver oil from low cost Balistid fish Sufflamen capistratus extracted by Soxhlet, Bligh and Dyer, direct steaming, solar extraction and Mc Gill and Moffat methods were assessed. The oil yield was high (70.3%) in Soxhlet method when compared with other methods. The physical properties such as solidification point, melting point, refractive index and moisture content of the extracted oil samples were differed between methods. The chemical properties like the acid value, free fatty acid (FFA) level and carotenoid content of the individual oil samples were showed extraction methods dependant variation. Fatty acid content was also showed variation between methods; polyunsaturated fatty acid (PUFA) content was high (23.07%) in Bligh and Dyer method. In all the oil samples, fat soluble vitamin K was more when compared with the other tested vitamins. Irrespective of methods of extraction, permissible level of heavy metals and minerals were recorded in the oil samples.     

Performance of a cryogenic vacuum system (COLDEX) with an LHC type beam

The cold bore experiment installed in the super proton synchrotron has been used to study the performance of a vacuum system operating at cryogenic temperatures in the presence of a large hadron collider (LHC) type proton beam. The ∼2 m long cryostat, which can be cooled below 3 K, is fitted with an actively cooled beam screen which can be temperature controlled between 5 and 100 K. Molecular desorption and deposited heat load measurements, with or without gas pre-condensation, have been performed. Implications to the LHC design and operation will be discussed.     

Application of the SUSAN filter to wavelet video-coding artifact removal

This paper proposes the application of the Single Univalve Segment Assimilating Nucleus (SUSAN) algorithm for the reduction of coding artifacts in wavelet video-coding schemes. The SUSAN filter is as an image-structure preserving non-linear filter with low computational complexity. The filter adapts its bandwidth and stop-band attenuation based on a simple pixel classification procedure. In addition to this initial proposition, the paper provides two extensions of the original 2-D filter to the temporal domain: a two-stage 2-D+T SUSAN filter and a pure 3-D SUSAN filter. Experimental results provided in the paper provide substantial evidence of the effectiveness of the proposed approaches in terms suppression of artifacts that are typical in wavelet coding. Comparative tests show that SUSAN and its proposed extensions outperform state-of-the-art post-processing algorithms both in terms of objective (PSNR) and perceptual (PQS) quality comparisons.     

He leaks in the CERN LHC beam vacuum chambers operating at cryogenic temperatures

The 27 km long large hadron collider (LHC), currently under construction at CERN, will collide protons beam at 14 TeV in the centre of mass. In the 8 arcs, the superconducting dipoles and quadrupoles of the FODO cells operate with superfluid He at 1.9 K. In the 8 long straight sections, the cold bores of the superconducting magnets are held at 1.9 or 4.5 K. Thus, in the LHC, ∼75% of the beam tube vacuum chamber is cooled with He.In many areas of the machine, He leaks could appear in the beam tube. At cryogenic temperature, the gas condenses onto the cold bores or beam screens, and interacts with the circulating beam. He leaks creates a He front propagating along the vacuum chambers, which might cause magnet quench.We discuss the consequences of He leaks, the possible means of detections, the strategies to localise them and the methods to measure their size.     

Vacuum performance of a carbon fibre cryosorber for the LHC LSS beam screen

A new carbon fibre material was developed at the Institute of Solid State Chemistry and Mechanochemistry at the Siberian Branch of the Russian Academy of Science (SB RAS) to meet the requirements of a cryosorber for the large hadron collider (LHC) vacuum chamber. The material must have a large sorbing capacity, a certain pumping speed, a working temperature range between 5 and 20 K, a low activation temperature (below room temperature), a certain size in order to fit into the limited space available and it should be easy to mount. The vacuum parameters of the LHC vacuum chamber prototype with a carbon fibre cryosorber mounted onto the beam screen were studied in the beam screen temperature range from 14 to 25 K at the Budker Institute of Nuclear Physics SB RAS. This carbon fibre material has shown sufficient sorption capacity for hydrogen at operational temperatures of the beam screen in the LHC long straight sections. It is also very important that this material does not crumble and makes a convenient fixation onto the beam screen in comparison to the widely used granulated charcoal. The problem of fluff and ways of reducing the quantity of fluff in the beam channel were studied. The results of these studies show that the carbon fibre material is a possible cryosorber-candidate for use in the LHC and other long vacuum system at cryogenic temperatures. The experimental set-up and results of measurements of the H₂ cryosorption capacity of this carbon fibre material are presented in this paper.     

Measurement and calculation of high-energy neutron spectra behind shielding at the CERF 120 GeV/c hadron beam facility

Neutron energy spectra were measured behind the lateral shield of the CERF (CERN-EU High Energy Reference Field) facility at CERN with a 120 GeV/c positive hadron beam (a mixture of mainly protons and pions) on a cylindrical copper target (7-cm diameter by 50-cm long). An NE213 organic liquid scintillator (12.7-cm diameter by 12.7-cm long) was located at various longitudinal positions behind shields of 80- and 160-cm thick concrete and 40-cm thick iron. The measurement locations cover an angular range with respect to the beam axis between 13 and 133°. Neutron energy spectra in the energy range between 32 MeV and 380 MeV were obtained by unfolding the measured pulse height spectra with the detector response functions which have been verified in the neutron energy range up to 380 MeV in separate experiments. Since the source term and experimental geometry in this experiment are well characterized and simple and results are given in the form of energy spectra, these experimental results are very useful as benchmark data to check the accuracies of simulation codes and nuclear data.Monte Carlo simulations of the experimental set up were performed with the FLUKA, MARS and PHITS codes. Simulated spectra for the 80-cm thick concrete often agree within the experimental uncertainties. On the other hand, for the 160-cm thick concrete and iron shield differences are generally larger than the experimental uncertainties, yet within a factor of 2. Based on source term simulations, observed discrepancies among simulations of spectra outside the shield can be partially explained by differences in the high-energy hadron production in the copper target.     

轮式车辆麦弗逊悬架转向梯形断开点位置优化设计

运用多刚体系统动力学中R-W方法,建立了轮式车辆麦弗逊悬架和转向系统运动方程,导出了系统关联矩阵、通路矩阵、体铰矢量矩阵以及系统约束方程。在此基础上建立了麦弗逊悬架转向梯形断开点位置优化模型。在优化模型中,根据转向要求创建出了一种权重函数,从而可以获得最佳的优化效果。     

江苏移动基于Mc口数据的高速铁路专网无线网络质量分析

对于高速铁路移动专网的架构、维护手段进行了全面的论述,并创新性实现了基于GSM移动网Mc口数据,对于高铁用户的各项感知指标全面分析测试,丰富并提高了针对高铁专网的维护手段和效率。这对于提高高铁专网的无线覆盖质量分析将发挥巨大作用,为提高用户满意度做出贡献。     

基于ADAMS的麦弗逊悬架导向机构参数优化

针对传统悬架优化过程求解困难且耗时的问题,提出基于ADAMS的悬架导向机构参数优化方案。通过分析麦弗逊悬架系统的运动学性能,得到与悬架性能相关的优化变量,进而完成悬架导向机构的参数优化。结果表明,该优化方案取得了较为理想的优化效果,在此基础上,归纳出悬架导向机构参数优化的仿真分析方法,对其它类型悬架的优化具有借鉴意义。