求和生成器的相关性分析

J.Dj,Golic运用线性序列电路逼进的方法来分析具有任意个输入的求和生成器,他猜想可以通过这种方法来获得所有具有最大相关系数的输入和输出线性函数对,但是他未给出证明。利用Walsh变换技术证明了当n是偶数的时候这个猜想成立。另外,还研究了求和生成器的相关系数总和,发现它与带1比特组合器的相关系数总和非常类似。

钟控密钥流生成器及其密码性能

提出了一种新的钟控密钥流生成器,由3个移位寄存器组成:两个被钟控的线性反馈移位寄存器A和B,一个提供钟控信息的非线性反馈移位寄存器C。设A、B和C的长度分别为l1、l2和l3。移位寄存器A和B的钟控信息由从移位寄存器C选取的两个比特串提供,移位的次数分别是两个比特串的汉明重量。研究了该生成器的周期、线性复杂度和k错线性复杂度,分析了这种密钥流生成器的安全性。

一类密钥流生成器的相关分析

多输出逻辑函数是构造密码系统的重要工具,相关免疫性是设计安全逻辑函数的重要准则.该文利用一种较为简单的方法证明了多输出逻辑函数相关免疫性两种刻划的等价性.还对一类利用多输出逻辑函数相关免疫函数构造的密钥流生成器进行了相关性分析,证明了这种构造方法是不成立的,并不能达到构造者期望的相关免疫性,并且分别利用Walsh变换技术和线性序列电路逼近方法找出了这类密钥流生成器的漏洞,从而说明这类生成器在相关攻击下是脆弱的.

A new prototype of self-pressurizing fuel tank for micro and nano-satellites

To increase effective load, light-weight micro-propulsion system is necessary for micro-satellites. Traditional propulsion systems including large and heavy high-pressure vessels are difficult to be scaled down to fulfill the demand of micro-satellites. In this article, a novel self-pressurizing fuel tank without high-pressure gas vessel is proposed. When some liquid propellant is consumed, pressure is compensated with CO2 released by heating NH4HCO3 powder in the fuel tank. Comparing with other types of self-pressurizing liquid fuel tank, a gas generator with special and simple structure was designed to stop or continue the NH4HCO3 decomposition reaction easily, and consumed a small amount of energy to heat the powder effectively. Performance tests showed that this new prototype is very suitable for micro-thrusters.

CLIGEN非降水要素在黄土塬区的适用性评估

许多基于物理机制的水文和作物模型需要日序列气象数据来驱动,CLIGEN是为WEPP等模型产生气候输入文件的天气发生器,可以产生10个日序列气象变量来满足这种需要,但是其在中国的适用性需要进行评估。研究的目标是利用黄土高原陕西长武1957~2001年的气象数据评估CLIGEN产生非降水要素(最高温度、最低温度、露点温度、太阳辐射和风速)的能力。结果表明,CLIGEN对最高温度、最低温度和露点温度的模拟效果较好,对太阳辐射和极端气候事件的模拟效果较差,对风速的模拟效果最差。相关性检验表明CLIGEN很好地保持了气象要素的季节性,这对模拟农业生产是非常重要的;但是没有保留气象要素逐日的自相关和互相关性,进而导致产生的温度变化不符合连续渐变的规律。

A double wavelength DFB laser with an identical active area for CWDM

A novel distribute feedback (DFB) laser which gave two different wavelengths under two distinct work conditions was fabricated. The laser consists of two Bragg gratings with different periods corresponding to wavelength spacing of 20 nm in an identical active area. When driving current was injected into one of the different sections separately, two different wavelengths at 1542.4 and 1562.5 nm were realized. The side mode suppression ratio (SMSR) of 45 dB or more both for the two Bragg wavelengths were achieved. The fabricating process of the laser was just the same as that of traditional DFB laser diode. This device can be potentially used in coarse wavelength division multiplexer (CWDM) as a promising light source and the technology idea can be used to enlarge the transmission capacity in metro area network (MAN).

Strained MQW electro-absorption modulators with high extinction ratio and low capacitance

We fabricate an electro-absorption modulator for optical network system using a new strategy, the improved modulation properties of the strained InGaAs/InAlAs MQW show it's polarization independent, high extinction ratio (> 40dB) and low capacitance (C <0.6pF) which can achieve an ultra-high frequency(> 10GHz). The device is be used in 10Gbps optical time division multiplex (OTDM) system as a signal generator.

Mode theory and analysis of planar array waveguides

Bloch modes can be excited in planar array due to its periodic lateral refractive index. The power coupled into each eigenmode of the array waveguides is calculated through the overlap integrals of the input field with the eigenmode fields of the coupled infinite array waveguides projected onto the x-axis. Low losses can be obtained if the transition from the array to the free propagation region is adiabatic. Due to the finite resolution of lithographic process the gap between the waveguides will stop abruptly, however, when the waveguides come into too close together. Calculation results show that losses will occur at this discontinuity, which are dependent on the ratio of the gap between the waveguides and grating pitch and on the confinement of field in the array waveguides. Tapered waveguides and low index contrast between the core and cladding layers can lower the transmitted losses.

Generation of 10 GHz, 1.9 ps optical pulse train using semiconductor optical amplifier and silica-based highly nonlinear fiber

We propose a simple approach to generate a high quality 10 GHz 1.9 ps optical pulse train using a semiconductor optical amplifier and silica-based highly nonlinear fiber. An optical pulse generator based on our proposed scheme is easy to set up with commercially available optical components. A 10 GHz, 1.9 ps optical pulse train is obtained with timing jitter as low as 60 fs over the frequency range 10 Hz-1 MHz. With a wavelength tunable CW laser, a wide wavelength tunable span can be achieved over the entire C band. The proposed optical pulse generator also can operate at different repetition rates from 3 to 10 GHz.

冷却储存实验环功率源的设计与计算

RF system of HIRFL-CSRe(cooling storage experimental ring)was designed by ourselves and manufactured domestically,which operates in the frequency range of 0.5~2.0 MHz at first and second harmonic modes.Based on detailed engineering calculation,the design of RF generator was completed.It will work not only in CW mode but also in the mode of ramping pulse modulation,and the maximum power is up to 70 kW.It satisfies the requirement of 10 kV maximum deceleration voltage to capture the irradiative beam and decel...中文摘要：对兰州重离子加速器冷却储存环实验环(CSRe)的高频系统功率源的设计作了详细的工程计算,工作频率范围为0.5～2.0MHz,工作于基波及二次谐波模式,发射机不仅能工作于点频连续波模式,而且还可以工作在扫频调制模式,输出最大功率达到70kW。满足最高加速或减速电压10kV的设计要求,能够用于捕获放射性次级束并将束流的能量从400MeV/u减速到30MeV/u。

RF system design and measurement of HIRFL-CSRe

An RF system for the CSRe (cooling storage experimental ring) is designed and manufactured domestically. The present paper mainly describes the RF system design in five main sections: ferrite ring, RF cavity, RF generator, low level system and cavity cooling. The cavity is based on a type of coaxial resonator which is shorted at the end with one gap and loaded with domestic ferrite rings. The RF generator is designed in the push-pull mode and the low level control system is based on a DSP+FGPA+DDS+USB inter...

Experimental results of helicon sources

Helicon plasma source is known as an efficient generator of uniform and high density plasma. A helicon plasma source was developed for the investigation of plasma striping and plasma lens at the Institute of Modern Physics, CAS. In this paper, the characteristics of helicon plasma have been studied by using Langmuir four-probe and a high plasma density up to 3.9×1013 /cm3 has been achieved with the Nagoya type III antenna. In the experiment, several important phenomena have been found: (1) for a given magnetic induction intensity, the plasma density became greater with the increase of RF power; (2) the helicon mode appeared at the RF power between 300 W and 400 W; (3) the plasma density gradually tended to saturation as the RF power increased to the higher power; (4) a higher plasma density can be obtained by a good matching between the RF power and the magnetic field distribution. The key issue is how to optimize the matching between the RF power and the magnetic field. Moreover, some tests on the extraction of ion beam were performed, and the preliminary results were given. The problems which existed in the helicon ion source will be discussed and the increase in beam density will be expected by extraction system optimum.

多路谱仪放大器输出信号的读出与数据采集

A read-out and data acquisition system for the outputs of multi-channel spectroscopy amplifiers is introduced briefly in this paper.The 16-channel gating integrator/multiplexer developed by us and PXI-DAQ card are used to construct this system.A virtual instrument system for displaying,indicating,measuring and recording of output waveform is accomplished by integrating the PC,hardware,software together flexibly based on the Lab Windows/CVI platform in our read-out and data acquisition system.In this system,...中文文摘：简要介绍一个针对多路谱仪放大器的读出与数据采集方法与系统。该系统基于16通道门积分/选通输出电路和通用PXI-DAQ卡构建。利用Lab Windows/CVI平台构建虚拟仪器,灵活地将计算机、硬件、软件结合起来,设计了一个读出与数据采集系统。在该系统中,一个ADC通道可以面对16个谱仪放大器的输出,有效地提高了系统的集成度,降低了数据采集系统的成本。该设计为利用通用型谱仪放大器构建数百参数的信号读出与数据采集系统提供了一种新的方法。通过实验验证,证明该系统具有智能化、可靠性高、实时性强、成本低等优点。