Evidence that far-infrared radiation promotes growth of Xenopus laevis

In most ectotherms, environmental temperature has differential effects on growth and differentiation. For example, amphibian size at maturity decreases with increasing temperature. To address how radiant heat in the form of far-infrared radiation (FIR) may affect development of the aquatic ectotherm Xenopus laevis, we continuously irradiated swimming larvae as they developed into young adults. Here we report evidence that FIR promotes growth of these organisms in an aqueous environment.     

FIR数字滤波器的优化设计

针对常系数FIR数字滤波器,采用CSD编码和简化加法器图技术来减少FIR实现过程中乘累运算的加减次数,从而降低了其对硬件资源的消耗;在结构上采用分布式算法和流水线技术进行优化,显著的提高了FIR数字滤波器的工作速度。通过实例对每一种改进方法进行了对比验证,说明达到了节省芯片资源或提高实现频率的目的。     

遥感图像数据压缩新技术研究

研究了遥感图像数据压缩新技术。利用半正交小波基和对偶系设计了具有严格线性相位和精确重建特性的ＦＩＲ滤波器组，将其应用于遥感图像的数据压缩，取得了良好的成果。     

小型CPT原子钟的数字电路优化研究

CPT原子钟是一种体积小、功耗低、指标优的新型原子钟。本文对小型CPT原子钟数字滤波算法开展优化研究,采用CIC滤波器前端滤波,低阶FIR滤波器后端滤波。新滤波模块在保证相同的噪声抑制比的情况下,节约逻辑资源,降低整钟功耗。基于以上方案实现的滤波模块,获得了55dB的滤波效果,同时节省了约42%的FPGA逻辑资源。     

InfraRed Astronomy Satellite Swarm Interferometry (IRASSI): Overview and study results

The far-infrared (FIR) regime is one of the few wavelength ranges where no astronomical data with sub-arcsecond spatial resolution exist yet. Neither of the medium-term satellite projects like SPICA, Millimetron or OST will resolve this malady. For many research areas, however, information at high spatial and spectral resolution in the FIR, taken from atomic fine-structure lines, from highly excited carbon monoxide (CO) and especially from water lines would open the door for transformative science. These demands call for interferometric concepts. We present here first results of our feasibility study IRASSI (Infrared Astronomy Satellite Swarm Interferometry) for an FIR space interferometer. Extending on the principal concept of the previous study ESPRIT, it features heterodyne interferometry within a swarm of five satellite elements. The satellites can drift in and out within a range of several hundred meters, thereby achieving spatial resolutions of <0.1 arcsec over the whole wavelength range of 1–6 THz. Precise knowledge on the baselines will be ensured by metrology methods employing laser-based optical frequency combs, for which preliminary ground-based tests have been designed by members of our study team. We first give a motivation on how the science requirements translate into operational and design parameters for IRASSI. Our consortium has put much emphasis on the navigational aspects of such a free-flying swarm of satellites operating in relatively close vicinity. We hence present work on the formation geometry, the relative dynamics of the swarm, and aspects of our investigation towards attitude estimation. Furthermore, we discuss issues regarding the real-time capability of the autonomous relative positioning system, which is an important aspect for IRASSI where, due to the large raw data rates expected, the interferometric correlation has to be done onboard, in quasi-real-time. We also address questions regarding the spacecraft architecture and how a first thermomechanical model is used to study the effect of thermal perturbations on the spacecraft. This will have implications for the necessary internal calibration of the local tie between the laser metrology and the phase centres of the science signals and will ultimately affect the accuracy of the baseline estimations.     

IIR滤波器在芯片原子钟中的应用

芯片原子钟是具有小体积,低功耗特点的原子钟。本文采用了IIR滤波器方案对芯片原子钟物理系统输出信号进行处理,该方案有利于减小芯片原子钟的体积、提高芯片原子钟短期频率稳定度。实验结果表明,与FIR滤波方案相比,IIR滤波器使用的FPGA资源减小了约58%;与现有模拟滤波方案相比,使用IIR滤波器方案的芯片原子钟频率稳定度提高了1.4×10~(-10)τ~(-1/2)(τ=1s-100s),电路面积减小了10%。     

Strong magnetic field effect on the dissolution process of tetragonal lysozyme crystals.

Either a homogeneous or inhomogeneous magnetic field has been known to dampen the protein crystal growth. To date the mechanism is not clear. However, it was generally proposed that the magnetic field may dampen the convection in the solution, resulting in a reduced crystal growth rate and possibly a good crystal quality, similar to the case of protein crystal growth in space. To understand the mechanism of the magnetic field effect on protein crystal growth, further explorations on the magnetic field effect on protein solution, on the processes of crystal growth and dissolution, and on different crystallization (solution) systems, should be valuable. In this paper we present our recent efforts to study magnetic field effects on the dissolution processes of tetragonal lysozyme crystals under a strong magnetic field. A layer of oriented tetragonal lysozyme crystals was prepared under a temperature gradient and magnetic field, after that the crystals were dissolved by increasing the temperature of the solution. The lysozyme molecules will diffuse upwards due to the steep concentration gradient at the lower side of the cell caused by the dissolution. The evolution of the concentration in the solution was measured in-situ using a Mach-Zehnder interferometer. The results confirmed that the dissolution process of the crystals was slowed by the magnetic field. Judging from the concentration evolution versus time at different positions in the solution, we concluded that the apparent diffusion coefficient of lysozyme molecules was decreased by the magnetic field. The results were discussed using a suspended crystal model in the initial dissolution stage.     

时频重叠复用系统的低复杂度序列检测算法

利用时频重叠信号(Overlapped Hybrid-Division Multiplexing, OVHDM)实现高频谱效率数据传输,性能优于多电平调制方案.介绍了OVHDM信号模型以及最佳检测算法.为了降低检测的复杂度,提出了联合软干扰消除的序列检测算法--SIC-SE:软干扰消除后的各子载波数据流,在序列检测前首先通过基于快速矩阵逆的有限冲激响应滤波器.该算法的检测复杂度远低于最大似然检测算法,性能优于传统的软干扰消除算法.仿真表明,基于该检测算法的编码OVHDM系统性能优于使用相同信道编码的QAM-OFDM系统.     

Spaceflight hardware for conducting plant growth experiments in space: the early years 1960-2000.

The best strategy for supporting long-duration space missions is believed to be bioregenerative life support systems (BLSS). An integral part of a BLSS is a chamber supporting the growth of higher plants that would provide food, water, and atmosphere regeneration for the human crew. Such a chamber will have to be a complete plant growth system, capable of providing lighting, water, and nutrients to plants in microgravity. Other capabilities include temperature, humidity, and atmospheric gas composition controls. Many spaceflight experiments to date have utilized incomplete growth systems (typically having a hydration system but lacking lighting) to study tropic and metabolic changes in germinating seedlings and young plants. American, European, and Russian scientists have also developed a number of small complete plant growth systems for use in spaceflight research. Currently we are entering a new era of experimentation and hardware development as a result of long-term spaceflight opportunities available on the International Space Station. This is already impacting development of plant growth hardware. To take full advantage of these new opportunities and construct innovative systems, we must understand the results of past spaceflight experiments and the basic capabilities of the diverse plant growth systems that were used to conduct these experiments. The objective of this paper is to describe the most influential pieces of plant growth hardware that have been used for the purpose of conducting scientific experiments during the first 40 years of research.     

空间低温溶液晶体生长的地基实验

首次使用疏水型聚四氟乙烯微孔滤膜,利用其透气不透水的特性,密封晶体生长容器,采用恒温蒸发法进行晶体生长.溶剂通过蒸发离开生长容器后,被生长容器外的吸附剂吸附,使得溶液维持一定过饱和度,以实现单晶的连续生长.在此基础上研制出一套空间低温溶液晶体生长地基模拟装置.利用此装置进行了一系列地基模拟实验,获得一批高质量α-LiIO₃单晶,证实了该生长装置的溶剂蒸发量和容器密封性能够满足空间低温溶液晶体生长需要,为未来空间低温溶液晶体生长实验奠定了基础.      

二维静电孤立波的粒子模拟研究

利用二维粒子模拟程序研究了双流不稳定性激发静电波并演化为静电孤立波的物理过程.计算结果表明,在线性增长阶段,主要激发的是沿磁场传播的静电波;在非线性演化阶段,相邻的静电波会互相合并,直至形成静电孤立波,并可激发静电哨声波.还研究了磁场强度和离子温度对此过程的影响.当磁场强度比较小时,无法形成静电孤立波,只有磁场强度达到一定程度后静电孤立波才能形成;同时,离子温度会影响静电孤立波的稳定性,当离子温度比较小时,静电孤立波的稳定性减弱,在演化一段时间后会逐渐瓦解.      

温场可编程控制的小型空间晶体炉设计与测试

详细介绍了一台温场可编程控制的小型空间晶体炉。其工作原理是,在计算机控制下,炉膛温场发生有序地变化,完成晶体生长过程。由于没有机械运动部件,从而彻底消除了机械振动对微重力环境的干扰。此炉是为返回式卫星搭载试验而设计,配备以Ｉｎｔｅｌ８０ｃ３１为核心的计算机温度控制及数据采集系统。该系统采用数字ＰＩＤ方式独立调节加热器中７个结构相同的加热单元的温度,可以编程实现多种温场变化模式。     

Generation mechanism of the whistler-mode waves in the plasma sheet prior to magnetic reconnection

The whistler-mode waves and electron temperature anisotropy play a key role prior to and during magnetic reconnection. On August 21, 2002, the Cluster spacecrafts encountered a quasi-collisionless magnetic reconnection event when they crossed the plasma sheet. Prior to the southward turning of magnetospheric magnetic field and high speed ion flow, the whistler-mode waves and positive electron temperature anisotropy are simultaneously observed. Theoretic analysis shows that the electrons with positive temperature anisotropy can excite the whistler-mode waves via cyclotron resonances. Using the data of particles and magnetic field, we estimated the whistler-mode wave growth rate and the ratio of whistler-mode growth rate to wave frequency. They are 0.0016f_ce (Electron cyclotron frequency) and 0.0086f_ce, respectively. Therefore the whistler-mode waves can grow quickly in the current sheet. The combined observations of energetic electron beams and waves show that after the southward turning of magnetic field, energetic electrons in the reconnection process are accelerated by the whistler-mode waves.     

Development of a plant growth unit for growing plants over a long-term life cycle under microgravity conditions.

To study the effect of the space environment on plant growth including the reproductive growth and genetic aberration for a long-term plant life cycle, we have initiated development of a new type of facility for growing plants under microgravity conditions. The facility is constructed with subsystems for controlling environmental elements. In this paper, the concept of the facility design is outlined. Subsystems controlling air temperature, humidity, CO2 concentration, light and air circulation around plants and delivering recycled water and nutrients to roots are the major concerns. Plant experiments for developing the facility and future plant experiments with the completed facility are also overviewed. We intend to install this facility in the Japan Experiment Facility (JEM) boarded on the International Space Station.     

Characterization of a halotolerant-psychroloterant bacterium from dry valley Antarctic soil.

The saline soils of the ice free dry valleys of Victoria Land, Antarctica may provide the closest analog on Earth to Martian conditions. We have initiated a study aimed at examining microbial adaptations to the harsh environment of these dry valley soils. In this report we describe the characterization of one bacterium, strain A4a, isolated from Taylor Valley soil. Strain A4a was an obligately aerobic, orange-pigmented, Gram-positive coccus that grew over wide ranges of both temperature (0 degrees C-40 degrees C) and sodium chloride concentration (0-2.0M). The optimal temperature for growth at all NaCl concentrations was 25 degrees C. Phospholipid composition and guanine plus cytosine content of the DNA of the isolate indicate a close relation to the genus Planococcus.     

INTERFACIAL MASS TRANSPORT IN OXIDE CRYSTAL GROWTH

A space high temperature in situobservation instrument (SHITISOI) is dedicated to visualize and record the whole growth process of oxide crystal in high temperature melts and solutions. Model experiments using transparent liquids such as KNbO3,Li2B4O7+KNbO3 were chosen to investigate effects of interracial mass transport in oxide crystal growth. For the scaling of the coupled velocity, heat and concentration fields in KNbO3 crystal growth, a rotating crystal growth process was performed and the widths of interfacial concentration, heat and momentum transition zones (The "boundary layers") are obtained, which are 7.5×10-a, 8.6×10-2 and 4.4×10-1 cm,respectively. Hence one can expect that interfacial concentration gradient will be confined to a narrow layer and in region of major concentration change at the in terface. In order to study a mechanism based on the interfacial mass transport resulting from hydrodynamics, the growth of KNbO3 grain in high temperature Li2B4O7 and KNbO3 solutin was studied. The result shows that the pivotal feature in the KNbO3 crystal growth is the initiated by KNbO3 solute surface tension gra dient which is caused by the slow diffusion of KNbO3 solutes. Direct comparison of the model predictions and experimental observed phenomena demonstrate the predictive capability of this model.     

Electron temperature anisotropy effects on tearing mode in ion-scale current sheets

Recent two-dimensional (2-D) particle-in-cell (PIC) simulations have shown that there is a critical thickness of a current sheet, above which no significant saturation amplitude of the 2-D tearing (TI) mode can be expected. Here, we have introduced the initial electron temperature anisotropy (α_e0 = T_e⊥/T_e|| > 1), which is known to raise significantly the linear growth rates, and inspected if α_e0 > 1 can change the saturation level of the TI in a super-critical current sheet. Varying α_e0 and D (D: the current sheet half-thickness) systematically, we have found that while α_e0 boosts up the linear growth rate in both sub- and super-critical current sheets, macroscopic effects are obtained only in sub-critical current sheets, that is, energy transfer from the fastest growing short wavelength modes to longer wavelength modes are available only in the sub-critical regime. Since the critical thickness is a fraction of the ion inertial length, the tearing mode assisted by the electron temperature anisotropy alone, despite its significant boost in the linear growth rate, cannot be the agent for reconnection triggering in a current sheet of ion-scale thickness.     

汽车动态称重中的一种信号处理方法

为了提高汽车动态称重(WIM, Weigh-In-Motion)系统的称重精度,基于"逆模型"的思想,使用了自适应逆滤波器来充分抑制混叠在重量信号频带内的噪声信号.在有限长冲激响应滤波器的框架下,通过最小均方自适应算法,离线构建了WIM系统的逆系统,并用此逆系统作为一个新型的滤波器使用.而且,为了进一步提高称重精度,同时又采用了低通滤波器,来滤除分布在重量信号频带以外的噪声干扰.经过由自适应逆滤波器和低通滤波器构成的复合滤波器处理后, 称重结果较经参数估计方法处理后得到的结果,在称重精度上有了很大提高.      

TSK模糊神经网络及其约束优化学习算法

针对非线性动态系统特点,提出了一种基于TSK(Takagi-Sugeno-Kang)模糊模型的动态回归模糊神经网络DRFNN(Dynamic Recurrent Fuzzy Neural Network),该模糊神经网络由静态网络和动态网络两部分组成,其中静态网络用来实现规则的条件部分和解模糊部分的计算,由FIR动态滤波器实现的内反馈回归网络用来实现规则的结论部分,为了加快网络收敛速度,给出了基于约束优化算法的网络参数迭代算法,把网络结构优化和参数学习作为一个约束优化问题来解决.应用于非线性系统的辨识和控制仿真试验说明了DRFNN网络及其算法对解决非线性系统问题的有效性.