单根热管蓄冰研究

从技术角度研究和探讨了热管做为冰蓄冷装置的适用性,建立了单根热管蓄冰过程的数学模型,提出了蒸发段与冷凝段的长度配比;进行了一系列的实验,得到了不同工况下蓄冰厚度与时间之间的关系;结果表明热管蓄冰装置有着非常良好的蓄冰性能,为热管冰蓄冷装置的推广应用,提供整个装置的最优配置模式参数及强有力的理论依据及实验支撑。     

一种蓄冷式飞机地面空调车系统性能的研究

针对传统的飞机地面空调车存在不能以小功率用电保障大功率需求及冷量损失严重等问题,提出一种相变蓄冷式飞机地面空调车,简要分析了系统组成及其原理,对蓄、释冷系统进行了实验研究。结果表明:蓄冷工况下相变蓄冷材料在-2℃开始相变,蓄冷量达到200 kW时耗时38 min,蓄冷3 h蓄冷量为950 kW;释冷工况下蓄冷箱的释冷时间大于2 h,当进风温度为27℃、湿度为32%左右时出风温度为4℃、湿度为94%左右,出风压力及风量均在设计范围之内,设计合理。     

吸附制冷中的蓄冷研究

本文对一台余热驱动的带有水蓄冷器的单吸附器吸附空调系统进行了实验分析，研究了系统的吸附制冷过程和水蓄冷器的作用与影响，并对该吸附制冷系统中的吸附式蓄冷这种无能量损失的蓄冷方式的放冷过程进行了实验分析，比较了蓄冷式系统和双吸附器连续制冷系统的制冷性能及其优缺点．     

球形堆积床蓄冷空调系统实验性能研究

文中对球形堆积床蓄冷空调系统的蓄冷和放冷特性进行实验研究。在实验过程中,测量堆积床内流体温度、蓄冷时蒸发器进出口温度、放冷时换热器进出口温度以及室内机组进风和出风温度。通过测量的数据,得出蓄冷和放冷过程中的蓄冷、放冷速率和蓄冷、放冷量随时间的变化。在放冷时,出风温度稳定在16℃。因此,该系统可以用于空调系统的蓄冷和放冷过程,既有利于电力负荷"移峰填谷",又能满足室内温度调节的需求。     

不同环境温度下蓄冷式冷藏车温度场的模拟研究

环境温度对蓄冷式冷藏车箱体内部温度场与蓄冷材料释冷过程影响较大。本文以Na Cl水溶液为蓄冷材料,通过Solidworks建立蓄冷式冷藏车的物理模型,利用Gambit对物理模型进行网格划分,并采用Ansys软件对车内温度场和蓄冷材料相变过程进行模拟计算。结果表明:随着环境温度的升高,蓄冷板释冷过程加快,释放潜热时间缩短;车箱温度稳定在较高数值,且时间较短。环境温度为303K时,蓄冷材料完全融化为盐溶液需70.2h,车厢温度稳定在293K,维持时间为73.6h。环境温度与冷板温度温差较大,换热量较大,在计算工况下,热流密度为2.75W/h。     

BP神经网络模拟冰盘管蓄冷过程特性的可行性研究

文中基于BP神经网络方法对冰盘管蓄冷系统的整个蓄冷过程中的蓄冷动态特性参数进行模拟研究,根据实验研究数据对所建的BP神经网络进行网络训练,进而通过预测试验对预测网络进行检验。结果表明:利用BP神经网络方法对整个蓄冷过程中的蓄冷动态特性参数进行模拟的精确度明显高于传统模拟方法,可使研究者更全面、更精确地了解和掌握了蓄冷过程中蓄冷动态特性参数的变化情况,为设计和优化直接蒸发式冰盘管蓄冰系统提供了理论依据。     

复合低温相变蓄冷材料的实验研究

提出自行研制的一种复合低温相变蓄冷材料,通过实验分析了该蓄冷材料的融点、相变潜热和凝固融化过程曲线.该材料由有机物和无机物混合而成,用示差扫描量热仪(DSC)来测定该蓄冷材料的融点、相变潜热;用低温冰箱测试凝固融化过程材料的均匀稳定性.实验结果表明,该材料具有良好的性能,适用于医药、食品、冰箱及冷库等蓄冷装置中.     

蓄冷球堆积床动态充冷性能模拟

根据蓄冷球和载冷剂之间的能量平衡,建立了蓄冷球堆积床充冷过程的数理模型。该模型考虑了载冷剂与蓄冷球之间的换热系数变化、载冷剂的导热、相变蓄冷材料的过冷度以及蓄冷球堆积床热损失的影响。采用数值计算方法模拟了蓄冷球堆积床的充冷过程,讨论了载冷剂入口温度、初始温度和流速对充冷过程蓄冷材料温度、载冷剂温度和蓄冰率的影响。     

空调蓄冷材料研究现状及其新进展

分析了空调蓄冷材料研究现状及存在的一些问题 ,提出研制一种新型空调复合蓄冷材料 ,通过实验 ,分析该蓄冷材料的融点、融解热等热学性能。并通过实验研究寻找到了一种新型空调蓄冷材料 ,测试结果表明该蓄冷材料具有较高的相变潜热、适宜的相变温度和较好的热稳定性 ,因此可被应用于蓄冷空调系统中。     

冰盘管排列密度对蓄冷速率影响的实验研究

设计了蒸发器盘管排列密度可以改变的直接蒸发冰盘管蓄冷装置,在高、中、低三种盘管排列密度情况下,进行了蓄冷槽内载冷剂在自然对流和强制对流下的静态和动态蓄冷实验,研究了盘管排列密度和蓄冷状态对蓄冷速率的影响。结果显示:高密度系统平均蓄冷速率较低密度系统提高27.9%以上,动态系统平均蓄冷速率较静态系统提高2%左右。     

Hybrid Wavelength and Code Division Multiple Access in Optical Networks

A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Research on beamforming method for dual-line array with space mismatch between the two line arrays

The performance of port/starboard discrimination of dual-line array will be seriously degraded when the space between the two line arrays of the dual-line array is mismatched. The directivity function of the delay-sum and delay-subtract beamforming is deduced and the port/starboard discrimination of the delay-sum and delay-subtract beamforming is also studied both under the ideal status and the status under which the space between the two line arrays of the dual-line array is mismatched. Analysis results show the delay-subtract beamforming has better performance of port/starboard discrimination. At last, the sea trial results demonstrate the theoretical results.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Retrieval of ultraviolet skylight radiances and O3 slant column densities from balloon-borne limb spectrometer

With a novel light-weight and absolutely calibrated ultraviolet （UV） spectrometer, UV skylight radiances and O3 slant column densities are measured by balloon-borne limb measurements in Xinjiang area, China. UV skylight radiances measured at the height of 31 km are compared with the results from Modtran in the wavelength range from 290 to 420 nm. O3 slant column densities are derived from radiance spectra in the Huggins bands （320 - 335 nm） using differential optical absorption spectroscopy method. And the parameter exhibits a good correlation with the same value simulated by radiative transfer model （Tracy）. The O3 profile simultaneously measured by an O3 sonde is used as input in Tracy calculations. The O3 sonde is launched on the same balloon.     

Design optimization of highly sensitive LSPR enhanced surface plasmon resonance biosensors with nanoholes

For breaking through the sensitivity limitation of conventional surface plasmon resonance (SPR) biosensors, novel highly sensitive SPR biosensors with Au nanoparticles and nanogratings enhancement have been proposed recently.But in practice, these structures have obvious disadvantages.In this study, a nanohole based sensitivity enhancement SPR biosensor is proposed and the influence of different structural parameters on the performance is investigated by using rigorous coupled wave analysis (RCWA).Electromagnetic field distributions around the nanohole are also given out to directly explain the performance difference for various structural parameters.The results indicate that significant sensitivity increase is associated with localized surface plasmons (LSPs) excitation mediated by nanoholes.Except to outcome the weakness of other LSP based biosensors, larger resonance angle shift, reflectance amplitude, and sharper SPR curves' width are obtained simultaneously under optimized structural parameters.     

Polymer gratings based on photopolymerization for low-order distributed feedback polymer lasers

Novel polymer distributed feedback(DFB)gratings are fabricated based on photopolymerization to reduce lasing threshold of polymer lasers.A photopolymer formulation sensitive to 355-nm ultraviolet(UV)light is proposed for the fabrication of polymer gratings and it can be used to form polymer films by spin-coating process.A very low surface-relief depth ranging from 12.5 to about 1.0 nm has been demonstrated with a refractive-index modulation of about 0.012.The experimental results indicate that such polymer gratings have promising potentials for the fabrication of low-order DFB organic semiconductor lasers.     

A novel methodology for photometric compensation of projection display on patterned screen

We propose a novel methodology based on the projector-camera (ProCam) system to address the photometric compensation issue for the projection display on the patterned screen.The patterned screen is treated as the combination of a perfect white screen and a color modulator.The perfect white screen is used to automatically and accurately characterize the ProCam system offline using the polynomial model,and the parameters of the color modulator can be efficiently recovered by employing only two gray images based on the linear reflectance model.The experimental results show that the color artifacts of the display image can be greatly improved with this methodology,which demonstrates its feasibility and validity in the photometric compensation.