制冰方式的研究

文中提出一种新型的浸润式动态制冰方式,并利用数值模拟的方法对新型制冰方式和传统滑落式制冰方式进行了对比研究。结果表明,在制冰时间相等的条件下,新型制冰方式的制冰量提高了约19%。在制冰量相等的条件下,制冰周期平均缩短了10分钟,蓄冰周期平均缩短了约2.3小时。此外,新型制冰机组采用的脱冰方式可以减小冷凝器的换热面积。     

氰化给体中分子间相互作用促进的全小分子光伏混合物的超快电子转移

氰基取代被认为是优化全小分子有机太阳能电池性能的可行方法. 然而,氰基取代对太阳能电池中电荷产生动力学的影响仍未得到探索. 本文光谱研究表明,在全小分子太阳能电池中,氰化给体中增强的分子间电荷转移相互作用会显著促进共混物中的电子转移. 实验发现,在氰基取代给体中,分子间相互作用引起的离域激发,在混合物中会进行超快电子转移. 相比之下,在没有氰基取代的给体中剩余的局域激发态,并没有积极参与电荷分离. 此发现很好地解释了为何氰化取代给体的共混物器件的性能会得到提升,表明可以通过调控分子间相互作用、来优化全小分子器件性能.     

消荧光现象与表面谐波产生

消荧光现象是激光与物质表面非线性相互作用的结果，这是一种普遍现象。在表面谐波产生的研究中，它常常被忽略。大量研究表明：表面谐波产生与消荧光现象，有着密切的内在联系。本文以消荧光观点详细讨论了表面谐波产生的机制，提出了表面谐波产生的消荧光模型。新机制可归纳为：（ａ）多光子受激吸收产生消荧光光斑，（ｂ）激光热效应等促进自发辐射转向准受激辐射，（ｃ）伴随荧光消失，部分产生荧光的激光能量转换为产生表面谐波     

谈教学中的绝对化倾向——教材中两道练习题引起的困惑

1两道练习题的疑问 北京教育出版社出版,物理通报杂志社编,九年义务教育教科书<物理>(新版)有两道题引起任课教师议论,不时有电话向笔者询问.     

Spectrum analysis of all parameter noises in repetition-rate laser pulse train

The theoretical investigation of all parameter noises in repetition-rate laser pulse train was presented. The expression of power spectrum of laser pulse trains with all parameter noises was derived, and the power spectra of pulse trains with different noise parameters were numerically simulated. By comparing the power spectra with and without pulse-width jitter, we noted that pulse-width jitter could not be neglected compared with amplitude noise and timing jitter and contributed a great amount of noise into the power spectrum under the condition that the product of pulse width and angular frequency was larger than 1.     

Variational iteration method for solving perturbed mechanism of western boundary undercurrents in the Pacific

A class of perturbed mechanisms for the western boundary undercurrents in the Pacific is considered. The model of generalized governing equations is studied. Employing the method of variational iteration, an approximate solution of corresponding model is obtained. It is proved from the results that the solution for the variational iteration method can be used for analysing operation of the perturbed mechanism of western boundary undercurrents in the Pacific.     

Load optimal design for a primary test stand facility based on a zero-dimensional load model

In order to couple the numerical simulation of a primary test stand driver with an optimal load design, a zero-dimensional wire array load model is designed based on the Saturn load model using PSPICE, which is an upgraded version of the Simulation Program with Integrated Circuit Emphasis (SPICE) designed by the ORCAD Corporation to perform circuit simulations. This paper calculates different load parameters and discusses factors influencing the driving current curve. With appropriate driving current curves chosen, further magneto-hydrodynamic calculations are carried out and discussed to provide the best results for experiments. The suggested optimal load parameters play an important role in experimental load design.     

Security analysis of a spatiotemporal-chaos-based cryptosystem

An S-box modified one-way coupled map lattice is applied as a chaotic cryptograph. The security of the system is evaluated from various attacks currently used, including those based on error function analysis, statistical property analysis, and known-plaintext and chosen-ciphertext analytical computations. It is found that none of the above attacks can be better than the brute force attack of which the cost is exhaustively quantitated by the key number in the key space. Also, the system has fairly fast encryption (decryption) speed, and has extremely long period for finite-precision computer realization of chaos. It is thus argued that this chaotic cryptosystem can be a hopeful candidate for realistic service of secure communications.     

Synthesis and characterization of Sr3Al2O6：Eu2＋, Dy3＋ phosphors prepared by sol-gel-combustion processing

A type of red luminescent Sr3Al2O6:Eu2+, Dy3+ phosphor powder is synthesised by sol-gel-combustion processing, with metal nitrates used as the source of metal ions and citric acid as a chelating agent of metal ions. By tracing the formation process of the sol-gel, it is found that it is necessary to reduce the amount of NO3- by dropping ethanol into the solution for forming a stable and homogeneous sol-gel. Thermogravimetric and Differential Scanning Calorimeter Analysis, x-ray diffractionmeter, scanning electron microscopy and photoluminescence spectroscopy are used to investigate the luminescent properties of the as-synthesised Sr3Al2O6:Eu2+, Dy3+. The results reveal that the Sr3Al2O6 crystallises completely when the combustion ash is sintered at 1250 C. The excitation and the emission spectra indicate that the excitation broadband lies mainly in a visible range and the phosphors emit a strong light at 618 nm under the excitation of 472 nm. The afterglow of (Sr0.94Eu0.03Dy0.03)3Al2O6 phosphors sintered at 1250 ℃ lasts for over 1000 s when the excited source is cut off.     

互感系数M12=M21的证明

从定义、磁能、磁矢势、磁偶极子、自由能5个方面出发分别证明了互感系数M12=M21,并对几种证明方法进行了分析对比,提出了自己的看法.