用多焦点全息透镜实现多重谱分数傅里叶变换

提出用多焦点全息透镜实现多重谱分数傅里叶变换.利用全息方法通过一次曝光制作出多焦点的全息透镜,分析了用此全息元件实现这种变换的条件,并在实验上实现了多重谱分数傅里叶变换. 实验结果表明这种变换方法简便可行,可广泛应用于多通道光学信息处理系统及多目标图像识别系统中.     

Velocity spectrum for non-Markovian Brownian motion in a periodic potential

Non-Markovian Brownian motion in a periodic potential is studied by means of an electronic analogue simulator. Velocity spectra, the Fourier transforms of velocity autocorrelation functions, are obtained for three types of random force, that is, a white noise, an Ornstein—Uhlenbeck process, and a quasimonochromatic noise. The analogue results are in good agreement both with theoretical ones calculated with the use of a matrix-continued-fraction method, and with the results of digital simulations. An unexpected extra peak in the velocity spectrum is observed for Ornstein-Uhlenbeck noise with large correlation time. The peak is attributed to a slow oscillatory motion of the Brownian particle as it moves back and forth over several lattice spaces. Its relationship to an approximate Langevin equation is discussed.     

偶联剂修饰纳米磁性粒子红外光谱及相关分析

以三氯化铁水溶液作前驱体，采用部分还原沉淀法，通过控制一些影响反应的参数，制备纳米磁性粒子(magnetic nanoparticles，MNes)，并分别用Z-6020，Z-6030和Z-6040硅烷偶联剂对其进行表面修饰．利用红外光谱、古埃磁天平、可见光分光光度计等手段，对MNPs的表面包覆官能团、磁化率、稳定性等进行表征．红外光谱分析表明，选用不同的偶联剂修饰MNPs，可以在其表面包覆各种活性的有机基团，除都含有大量-OH之外，用Z-6020修饰的MNPs还含有-NH2和-NH；用Z-6030修饰的，还含有-C-O和-C-C；用Z-6040修饰的，还含有-C-O，-C-O-C和-C-OH．同时，用Z-6020修饰的MNPs磁化率最高，稳定性较差；用Z-6040的，磁化率次之，稳定性最好；用Z-6030的，磁化率最低，稳定性最差．     

Towards Strong Duality in Integer Programming

We consider in this paper the Lagrangian dual method for solving general integer programming. New properties of Lagrangian duality are derived by a means of perturbation analysis. In particular, a necessary and sufficient condition for a primal optimal solution to be generated by the Lagrangian relaxation is obtained. The solution properties of Lagrangian relaxation problem are studied systematically. To overcome the difficulties caused by duality gap between the primal problem and the dual problem, we introduce an equivalent reformulation for the primal problem via applying a pth power to the constraints. We prove that this reformulation possesses an asymptotic strong duality property. Primal feasibility and primal optimality of the Lagrangian relaxation problems can be achieved in this reformulation when the parameter p is larger than a threshold value, thus ensuring the existence of an optimal primal-dual pair. We further show that duality gap for this partial pth power reformulation is a strictly decreasing function of p in the case of a single constraint. Dedicated to Professor Alex Rubinov on the occasion of his 65th birthday. Research supported by the Research Grants Council of Hong Kong under Grant CUHK 4214/01E, and the National Natural Science Foundation of China under Grants 79970107 and 10571116.     

A 24-GHz Patch Array with a Power Amplifier/Low-Noise Amplifier MMIC

This paper presents an active patch array designed at 24 GHz. It can be used as a front-end component for a phased array. A series resonant array structure is chosen which is compact and easy excite. With 5 elements, the array proved a 12-dB antenna gain. A power amplifier and a low noise amplifier are designed on a single GaAs chip (PALNA). Bias switch is used in the PALNA, which greatly reduces the switch loss in a transceiver and increases the efficiency. 20-dB small signal gain is achieved in both power amplifier and low noise amplifier. The active patch array is built by the combination of the patch array and PALNA. The measured active gain of this antenna is 35-dB for the PA mode and 31-dB for the LNA mode. This active patch array can obtain an EIRP of 34 dBm with a total radiated power of 22dBm and a maximum PAE of 32%. To check the noise performance, we applied sources at both normal temperature and 77K (liquid nitrogen) and extracted the noise figure (3.5 dB) of the active antenna by the Y factor method. The results proved that the active antenna is working efficiently as both a transmitting and receiving antenna.     

Sums of Two Exact Powers

An asymptotic formula is obtained for the number of representations of an element of a finite field as a weighted sum of two prescribed powers of primitive elements. This generalises previous work on sums of primitive elements, including that relating to some conjectures of Golomb.     

磁化合成铁氧体催化机理的探讨

本文用磁化合成法制取了一种新型高效铁氧体催化剂,用高分辨分析电镜,测定了其晶体结构、化学组成和原子级的显微形貌;提出了一种催化机制的新见解和一个研制催化剂的新方法.     

水电工程规划设计方案的自动生成及评价

本文介绍了在水电工程规划设计时，如何利用三次自然样条插值函数在有限个方案的基础上自动生成无限多个方案，然后采用多目标综合决策模型在其中选择最优方案的一种方法．文中还给出了程序流程，并以某水电站正常蓄水位选择作为实例，对方法进行了验证，结果与专家决策完全吻合．     

受激喇曼散射在掺铒光纤放大器中的影响

本文在分析了均匀掺杂分布式光纤放大器（d－EDFA）的基础上，提出了沿传输方向掺杂浓度单调下降（单变），和降升结合（两变）的两种渐变型分布式光纤放大器，并用传输方程研究了透明传输和最佳掺杂浓度下，受激喇曼散射对均匀、单变和两变型三种d－EDFA的各种特性的影响．     

DCS和FCS及其在火电厂中的应用

介绍了集散控制系统和现场总线控制系统，并对它们在火电厂中的应用做了分析。