振动流化床冷渣器试验研究

本文提出了冷却高温炉渣的振动流化床技术，研制了集连续可控排放和冷却于一体的新型冷渣器工业装置．采用物理性质相异法较系统地研究了冷渣器内宽筛分物料的停留时间分布．对气固两相流的空气动力学特性和热态运行工况进行了试验研究和理论分析．结果表明，在风渣比为1．5～2．5Nm3／kg时，冷渣器的热回收率达到85％以上．     

模式转换弯曲振动超声换能器的研究

本文研制了一种由纵向振动夹心式压电换能器和弯曲振动细棒组成的纵一弯模式转换弯曲振动超声换能器，从理论上分析了此类换能器的两种振动模式，井推出了其共振条件．实验表明，换能器共振频率的测量值与理论值符合很好，弯曲振动换能器的能量转换效率较高，性能稳定，在实际生产中具有广泛的应用．     

沸腾床宽筛分物料平均粒径的确定

临界流化风速是沸腾床一个很重要的流体动力特性参数,目前它的计算公式很多,这些公式的实验依据绝大部分是用粒度小,较均匀的料层所得,对于沸腾燃烧锅炉中宽筛分混合物料的沸腾床不一定适用. 在沸腾燃烧锅炉中,为了计算宽筛分料层的临界流化风速,必须应用平均颗粒直径.当前应用最普遍的是颗粒重量百分比平均直径与颗粒比表面积平均直径,但是对于同一     

声化学反应器研究进展

自八十年代后期以来，超声应用于有机合成、金属有机化学、电化学、聚合物化学等领域，取得了大量研究成果，引起了越来越多的化学工作者的兴趣[1-4]．利用超声波获取化学效应时，有许多实验参数需要加以控制，诸如超声频率、声强、处理时间、体系温度、外部压力、溶剂以及反应物浓度等．因此，为了适应声化学研究的需要，必须设计合适的反应器．国际上在这方面的研究十分活跃[5-11]，近年来研制和发展了许多新型的声化学反应器．本文拟对近年来国际上出现的实验室用声化学反应器作一简要介绍，以期对我国这方面的工作有所促进．一、液哨式…     

流化床中颗粒最小悬浮速度的确定

一、前言 沸腾炉的沸腾速度通常是按临界流化速度为基准选取的,但是对于宽筛分物料,在临界流化速度下大颗粒并没有流化。随着风速增加,料层中流化的物料量增加,即由小颗粒沸腾逐渐过渡到大颗粒沸腾,直至整个料层达到沸腾状态,颗粒完全悬浮时的最小风速称为最小悬浮速度W_(fs)。(见图1)。     

宽筛分燃煤沸腾炉的扬析和夹带

一、前言 国内几台典型燃用劣质煤沸腾炉试验数据表明,沸腾炉固体不完全燃烧损失最大的是飞灰损失,严重影响沸腾燃烧技术的发展。其原因是宽筛分燃煤沸腾炉在正常运行情况下不可避免地有大量细颗粒被带走。至今已有很多学者对流化床的扬析和夹带这个流态化技术的重要课题作过研究,但多数研究是在单一粒径或窄筛分物料的化工流化床中进行。因此研究宽筛分沸腾炉床料的夹带和扬析规律,对于探索减少扬析损失的途径是十分有意义的。本文仅介绍浙江大学二个沸腾床试验台的冷态试验研究结果,提出了经验公式。     

声屏障和有源噪声控制声屏障

概述了声屏障降低噪声的原理和常用方法，提出了存在的不足，介绍了有源声屏障的降噪性能与发展动态，提出了进一步研究的设想。     

线膨胀仪的改进

线膨胀仪的改进王景阳（哈尔滨电工学院物理实验室）在测金属棒线膨胀系数时，部分院校一直使用５０年代产的线膨胀仪．它的测量是靠旋转螺杆接触，借助小灯的明暗观察接触情况，很不准确，测量误差较大．并且学生也观察不到受热伸长现象．改进后的仪器克服了上面的缺点，...     

热声热机场方程的改进计算

本文讨论热声热机于二种热力学媒质组成的热声变换堆内外，温度、速度和压力场所应满足的改进的场方程．以PI和dP_1／dx等作为待定参数时，速度u_1和温度T_1的解式．并讨论了解式的含意与实验结果的对照．     

关于声子的定义及性质

本文通过求解简谐近似的哈密顿量Ｈ０的本征值方程，得出晶格振动能量量子化的结论，引出声子概念．然后对声子的性质进行讨论，并与光子、经典气体的性质作比较，以便揭示声子的基本特性．     

Confederated Miniature Sieves as an Alternative to Nest Sieving

Miniaturized sieves (1/2 inch diameter) can be mounted in a spinning riffler system to obtain small representative powder samples which eventually can be sieved in situ without removing the miniature sieves from the riffler system. By mounting several different aperture sieves around the riffler a confederation of miniature sieves could replace nest sieving. The sieving surface for these new sieves is so small compared to that of the traditional eight inch sieve that one could consider using the more expensive electroformed sieving surfaces for all test sieves in the quality control laboratory.     

Sieving of H2 and D2 Through End-to-End Nanotubes

We study the quantum molecular sieving of H₂ and D₂ through two nanotubes placed end-to-end. An analytic treatment, assuming that the particles have classical motion along the axis of the nanotube and are confined in a potential well in the radial direction, is considered. Using this idealistic model, and under certain conditions, it is found that this device can act as a complete sieve, allowing chemically pure deuterium to be isolated from an isotope mixture. We also consider a more realistic model of two carbon nanotubes and carry out molecular dynamics simulations using a Feynman-Hibbs potential to model the quantum effects on the dynamics of H₂ and D₂. Sieving is also observed in this case, but is caused by a different process.     

Field measurements of sonic boom penetration into the ocean

Six sonic booms, generated by F-4 aircraft under steady flight at a range of altitudes (610-6100 m) and Mach numbers (1.07-1.26), were measured just above the air/sea interface, and at five depths in the water column. The measurements were made with a vertical hydrophone array suspended from a small spar buoy at the sea surface, and telemetered to a nearby research vessel. The sonic boom pressure amplitude decays exponentially with depth, and the signal fades into the ambient noise field by 30-50 m, depending on the strength of the boom at the sea surface. Low-frequency components of the boom waveform penetrate significantly deeper than high frequencies. Frequencies greater than 20 Hz are difficult to observe at depths greater than about 10 m. Underwater sonic boom pressure measurements exhibit excellent agreement with predictions from analytical theory, despite the assumption of a flat air/sea interface. Significant scattering of the sonic boom signal by the rough ocean surface is not detected. Real ocean conditions appear to exert a negligible effect on the penetration of sonic booms into the ocean unless steady vehicle speeds exceed Mach 3, when the boom incidence angle is sufficient to cause scattering on realistic open ocean surfaces.     

Design and application of phase photon sieve

The imaging principle of Fresnel zone plate and photon sieve were analyzed in this paper. The design and fabrication of phase photon sieve were discussed. The feasibility of using phase photon sieve to realize nano-lithography was analyzed, a novel lithography experiment system based on phase photon sieve was presented, which not only has higher resolution and image contrast than the Fresnel zone plate lithography but also have higher diffractive efficiency than the amplitude photon sieve lithography.     

Membranes and films of zeolite and zeolite-like materials

An ideal structure of zeolite membrane should be a slice of a perfect zeolite crystal attached on a porous metal or ceramic support. To maximize the throughput, the zeolite layer must be very thin, limited only by the cell dimension of zeolite. Separation of a mixture may then be achieved based on the molecular sieving ability of zeolite, which allows only molecules smaller than a critical size to pass through. A variety of methods have been reported for the preparation of zeolite membranes, but so far a perfect epitaxial zeolite layer is still out of reach and only a polycrystalline zeolite membrane can be obtained. The first part of this review focuses on the permeation of gases and vapors through a polycrystalline zeolite membrane as a separation means. The effect of microstructure on permeance will also be discussed, as well as the preparation methods leading to different microstructures. In addition to the usage as a shape-selective membrane, thin films of zeolite and zeolite-like molecular sieves can also serve as hosts for the encapsulation and orientation of guest atoms and molecules and their clusters. In the second part of this review, the production of layers of aligned microporous molecular sieve crystals on supports and the fabrication of supported thin zeolite-like nanoporous silica films as well as their potential applications on the preparation of advanced materials are discussed.     

非链式重复频率HF激光器激光介质净化技术

开展了分子筛对非链式电激励重频HF激光器中基态HF分子吸附技术研究,设计了新型的分子筛吸附装置,进行了大量的吸附实验,结果表明: 3A分子筛为有效的吸附剂,实现了HF激光器在50 Hz/20 s条件下运行时平均激光能量下降率小于5%,大大提高了激光能量的稳定性,延长了激光介质的使用寿命。开展了激光器工作于不同频率条件下使用3A型分子筛吸附装置时的激光能量情况研究,并通过实验方法获得了3A型分子筛的再生活化方法。     

Burgers方程的声速点故障问题

研究了在Burgers方程跨声速稀疏波计算中遇到的sonic point glitch问题,对它产生的原因及其与数值格式熵条件的关系进行了分析.对若干著名格式,按照是否满足熵条件进行了分类.为了消除sonic point glitch现象,提出了一种新的两步分裂方法,并用这种方法改进了一系列典型格式.数值试验表明这是一种很好的消除sonic point glitch的方法.     

Quantum effect induced reverse kinetic molecular sieving in microporous materials

We report kinetic molecular sieving of hydrogen and deuterium in zeolite rho at low temperatures, using atomistic molecular dynamics simulations incorporating quantum effects via the Feynman-Hibbs approach. We find that diffusivities of confined molecules decrease when quantum effects are considered, in contrast with bulk fluids which show an increase. Indeed, at low temperatures, a reverse kinetic sieving effect is demonstrated in which the heavier isotope, deuterium, diffuses faster than hydrogen. At 65 K, the flux selectivity is as high as 46, indicating a good potential for isotope separation.     

Broadband resonant cavity inside a two-dimensional sonic crystal

A rectangular cavity inside a two-dimensional sonic crystal was theoretically and experimentally characterized by examining its response to a cylindrical source emitting narrow-band filtered noise bursts with central frequencies ranging from 2 to 12 kHz. A broadband intensity resonance was observed for frequencies within the full band-gap region of the sonic crystal (5.5–6.5 kHz). Unlike ordinary resonances, this broadband resonance depends on the reflection properties of the sonic crystal forming the surrounding walls rather than on the geometry of the cavity.     

Enhancing transmission efficiency of bending waveguide based on graded sonic crystals using antireflection structures

The conventional antireflection coating (ARC) structure for sonic crystal devices is to place the cylinders at the interface between a sonic crystal device and a background medium. The radius of ARC cylinders and the distance between the ARC and the sonic crystal device are adjusted to obtain an optimal antireflection effect. We propose that ARC structures are directly designed by using the conventional ARC theory instead of scanning the geometric and spatial parameters of the conventional ARC structures. According to the concept of the effective refractive index of sonic crystals, the exact ARC structures can be implemented by sonic crystals. The transmission efficiency of a bending waveguide designed by graded sonic crystals can be enhanced by introducing the ARC structures based on sonic crystals. The performances of different ARC structure designs are compared and discussed.