ALP风管系统

介绍了意大利ＡＬＰ风管系统 ，该系统由铝箔聚氨酯夹心板制的复合风管，特种系统，附件，管道连接件及固定件组成。     

Low Loss Sintered Dielectric Resonators with HTS Thick Films

The combination of high-Qdielectric resonators and high-temperature superconducting (HTS) films offer many advantages in the area of cellular and satellite communications. The high cost of single crystal dielectrics and HTS thin films may be unattractive in certain applications. Superconducting thick films and polycrystalline ceramic dielectrics offer a high performance, low-cost alternative to high-Qthin film/single crystal dielectric resonators. The loss of polycrystalline ceramics of A1₂O₃, Ba(Mg_1/3Ta_2/3)O₃ (BMT), and Zr_0.875 Sn_0.25Ti0.875O₄ (ZTS) has been studied. Alumina, A1_2Oin3, has been studied as a model material for dielectric loss. Theory predicts that the loss in single crystal sapphire should follow aT ₅ dependence. However, at low temperatures the loss is dominated by extrinsic losses due to crystal imperfection, residual dopant atoms, dislocations, and other lattice defects and theT ₅ dependence does not hold. In polycrystalline alumina the intrinsic loss is immediately masked by these extrinsic losses, even at room temperature, and a simpleT dependence is observed. Results on polycrystalline alumina show that Q’s well in excess of 105 at 10 GHz and 77 K can be achieved in a design made compact by the use of a HTS thick film shield.     

Thermal fatigue behavior of squeeze cast, discontinuous alumina-silicate fiber-reinforced aluminum alloy (A356) composite

Microstructural damage mechanisms owing to thermal cycling and isothermal exposure at elevated temperature are studied for a short alumina-silicate fiber-reinforced aluminum alloy (A356) composite produced by pressure casting. The tensile strength of the metal matrix composite is found to degrade considerably in each case. An X-ray double-crystal diffraction method is employed to study the mechanisms of recovery in the matrix. The fractal dimension of the X-ray “rocking curves” for individual grains in the composite reflects the substructure formation owing to the rearrangement of dislocations into subdomain walls. Recovery by polygonization is more pronounced in the case of thermal cycling than for equivalent isothermal exposure. The residual stresses in the matrix that provide the fiber clamping force undergo more relaxation in the case of isothermal exposure. The two competing damage mechanisms, thermally activated recovery by polygonization and relaxation of clamping stresses in the matrix, result in identical strength degradation (25%) for both thermal cycling and isothermal exposure.     

自然通风的应用与研究

合理利用自然通风对改善室内空气品质及建筑节能有重要意义。介绍了自然通风应用与研究的几个主要方面及其研究现状，并指出了对其进一步开展研究的方向。     

2001～2010年中国天然气发电发展问题研究

本文在经过一年多的调查基础上,通过大量的定性和定量分析,研究了今后十年天然气发电在中国的发展,为投资者和决策者提出了很好的意见和建议,如天然气发电的优势和劣势、各地电网的项目规划、需要注意和解决的问题。