复杂阴极保护体系三维有限元建模研究

滨海电厂常以天然海水作冷却水,其碳钢水室和钛管凝汽器在实施阴极保护过程中,要求钢电位应低于-0.85V(vs.SCE),电位过正则碳钢保护不足,而钛的电位则须高于-0.75V(vs.SCE),电位过负则易使钛管发生氢脆损伤.研究牺牲阳极阴极保护,需先得出两种金属在阴极保护过程中的电位分布.本文在设计室建立碳钢水室钛管模型,根据该实验体系阴极保护过程的(稳态极化和恒电流极化)测定获得两种金属有效的边界条件,用有限元(FEM)计算在一个牺牲阳极阴极保护状态得到三维电位分布.计算结果和测量结果基本一致,为优化阴极保护设计提供了理论依据.     

高超声速飞行器热防护材料与结构的研究进展

高超声速飞行器是航空航天的一个重要发展方向,在未来国防安全中起着重要作用．高超声速飞行器热防护材料与结构是高超声速飞行器设计与制造的关键技术之一,它关系到飞行器的安全．高超声速飞行器热防护材料与结构主要有金属TPS热防护系统、超高温陶瓷、C/C复合材料等．从材料制备、抗氧化、力学与物理性能表征等方面综述了热防护材料与结构的研究与应用现状,评述了其发展趋势．     

基于SRLG不相关的共享保护算法的研究

通过对共享保护算法的深入分析,使用K条最短路和迭代思想的方法,提出了两种共享风险链路组不相关的共享保护算法,并在仿真平台上对两种算法的性能进行了仿真.KWFF算法借鉴了传统的K条最短路策略,并且在每一个波长平面上,都对新到业务进行了K条工作路由的计算,极大挖掘了网络中潜在的波长资源.而IFF算法由于引入了迭代的思想,避免了共享风险链路组问题中,所特别有“陷阱”问题的出现,并且利用两套权重计算公式,在计算工作路由和保护路由的时候,充分考虑了网络资源的实时变化情况.通过仿真数据可以看到,与以往算法相比,KWFF和IFF算法大大降低了网络阻塞率,并且提高了网络资源的使用效率.     

环保节水型冷却塔的研究

综合湿式冷却塔有热交换效率高且造价低而空气冷却器无水蒸发等特点,提出了环保节水型冷却塔.对该新型塔进行了理论分析,对塔内换热、气动力性能等进行了数值计算,对塔内空气换热器和填料层间的冷却负荷以及与风机性能等进行了耦合匹配,结合北方气候条件的计算分析表明新型塔确有良好的节水和环保效果.     

Silver Nanowires and Silanes in Hybrid Functionalization of Aramid Fabrics

New functionalization methods of meta- and para-aramid fabrics with silver nanowires (AgNWs) and two silanes (3-aminopropyltriethoxysilane (APTES)) and diethoxydimethylsilane (DEDMS) were developed: a one-step method (mixture) with AgNWs dispersed in the silane mixture and a two-step method (layer-by-layer) in which the silanes mixture was applied to the previously deposited AgNWs layer. The fabrics were pre-treated in a low-pressure air radio frequency (RF) plasma and subsequently coated with polydopamine. The modified fabrics acquired hydrophobic properties (contact angle Θ_W of 112–125°). The surface free energy for both modified fabrics was approximately 29 mJ/m², while for reference, meta- and para-aramid fabrics have a free energy of 53 mJ/m² and 40 mJ/m², respectively. The electrical surface resistance (R_s) was on the order of 10² Ω and 10⁴ Ω for the two-step and one-step method, respectively. The electrical volume resistance (R_v) for both modified fabrics was on the order of 10² Ω. After UV irradiation, the Rs did not change for the two-step method, and for the one-step method, it increased to the order of 10¹⁰ Ω. The specific strength values were higher by 71% and 63% for the meta-aramid fabric and by 102% and 110% for the para-aramid fabric for the two-step and one-step method, respectively, compared to the unmodified fabrics after UV radiation.     

Fabrication of extreme wettability patterns with water-film protection for organic liquids

Selective fabrication of superhydrophilic (S-philic) region on a superhydrophobic (S-phobic) surface requires complex technology and high cost, which has limited applications of extreme wettability patterns. In this paper, a twice-chemical-etching approach without special modification is used to prepare the extreme wettability patterns. Superhydrophobicity and superhydrophilicity can be successfully achieved after twice chemical etching for 20 seconds. The obtained patterns can maintain their extreme wettability for at least 30 days. Functional platforms with single-S-philic and multi-S-philic regions are fabricated to manipulate water and various organic liquids with water-film protection in an air environment.     

对密立根油滴实验的测量方法改进

利用对密立根油滴实验的改进解出了实验操作过程中的各种问题,提高学生的实验兴趣和理论联系实际的能力.     

Noise effect on Grover algorithm

The decoherence effect on Grover algorithm has been studied numerically through a noise modelled by a depolarizing channel. Two types of error are introduced characterizing the qubit time evolution and gate application, so the noise is directly related to the quantum network construction. The numerical simulation concludes an exponential damping law for the successive probability of the maxima as time increases. We have obtained an allowed-error law for the algorithm: the error threshold for the allowed noise behaves as ε_th(N) ∼1/N^1.1 (N being the size of the data set). As the power of N is almost one, we consider the Grover algorithm as robust to a certain extent against decoherence. This law also provides an absolute threshold: if the free evolution error is greater than 0.043, Grover algorithm does not work for any number of qubits affected by the present error model. The improvement in the probability of success, in the case of two qubits has been illustrated by using a fault-tolerant encoding of the initial state by means of the [[7,1,3]] quantum code.     

Study on the optical limiting properties of the mixed liquid of carbon black suspensions and green tea solution by multi-pulse laser

The optical limiting properties of the mixed liquid of carbon black suspensions (CBS) and green tea solution were studied by using an 8 ns laser pulse at 532\,nm. The optical limiting effects of the CBS and mixed liquid have been compared between 5 and 10\,Hz repetition frequencies with nanosecond laser pulse. The experimental results indicate that the optical limiting threshold of the sample with the incidence laser at 10\,Hz repetition frequency is lower than at 5\,Hz repetition frequency. The possible reasons for the influence of the repetition frequency on the samples are discussed. And by observing the optical radiant distributions when the laser pulse passing through different samples, a possible mechanism for the observed effects is suggested. At the same time, the result shows that the optical limiting of CBS is the dominant factor to optical limiting of the mixed liquid.     

Copyright protection in digital museum based on digital holography and discrete wavelet transform

A new method to protect the copyright of digital museum based on digital holography is proposed. The Fresnel hologram of watermark image is embedded in the object to be protected through discrete wavelet transform （DWT）. After the watermark detection, the copyright information appears in the reconstructed hologram. With the higher redundancy feature in the hologram, the proposed technique can actually survive several kinds of image processing. Experimental results prove that the presented method has good robustness in image protection.