散射对高温气体-碳黑颗粒混合物辐射传输的影响

基于全光谱k分布(Full spectrum k distribution,FSK)模型、MIE理论和有限体积法(Finite volume method,FVM),构建了均温、均质辐射参与性气体-碳黑颗粒混合物介质热辐射传输模型,并分析了碳黑不同尺寸、不同体积浓度以及介质不同路径长度和不同温度条件下,因忽略碳黑颗粒散射所导致的介质热辐射传输特性(如辐射热流、辐射源项)的计算误差。研究结果表明:体积分数不变,增大粒径,计算误差呈现出先增大后减小的趋势;数密度不变,增大粒径,或者粒径不变,增大体积分数,均将使得计算误差相应增大;粒径、体积分数不变,增大路径长度,或者升高介质温度,均将增大计算误差。通常对于含有大颗粒、高碳黑浓度的辐射参与性气体-碳黑颗粒混合物介质,碳黑颗粒散射不能忽略。     

Impact of rain on wave retrieval from Sentinel-1 synthetic aperture radar images in tropical cyclones

The main objective of our work was to investigate the impact of rain on wave observations from C-band (~5.3 GHz) synthetic aperture radar (SAR) in tropical cyclones. In this study, 10 Sentinel-1 SAR images were available from the Satellite Hurricane Observation Campaign, which were taken under cyclonic conditions during the 2016 hurricane season. The third-generation wave model, known as Simulating WAves Nearshore (SWAN) (version 41.31), was used to simulate the wave fields corresponding to these Sentinel-1 SAR images. In addition, rainfall data from the Tropical Rainfall Measuring Mission satellite passing over the spatial coverage of the Sentinel-1 SAR images were collected. The simulated results were validated against significant wave heights (SWHs) from the Jason-2 altimeter and European Centre for Medium-Range Weather Forecasts data, revealing a root mean square error (RMSE) of ~0.5 m with a 0.25 scatter index. Winds retrieved from the VH-polarized Sentinel-1 SAR images using the Sentinel-1 Extra Wide-swath Mode Wind Speed Retrieval Model after Noise Removal were taken as prior information for wave retrieval. It was discovered that rain did indeed affect the SAR wave retrieval, as evidenced by the 3.21-m RMSE of SWHs between the SAR images and the SWAN model, which was obtained for the ~1000 match-ups with raindrops. The raindrops dampened the wave retrieval when the rain rate was < ~5 mm/hr; however, they enhanced wave retrieval for higher rain rates. It was also found that the portion of the rain-induced ring wave with a wave number > 0.05 rad/m (~125 m wavelength) was clearly observed in the SAR-derived wave spectra.     

The role of DNA repair on cell killing by charged particles.

It can be noted that it is not simple double strand breaks (dsb) but the non-reparable breaks that are associated with high biological effectiveness in the cell killing effect for high LET radiation. Here, we have examined the effectiveness of fast neutrons and low (initial energy = 12 MeV/u) or high (135 MeV/u) energy charged particles on cell death in 19 mammalian cell lines including radiosensitive mutants. Some of the radiosensitive lines were deficient in DNA dsb repair such as LX830, M10, V3, and L5178Y-S cells and showed lower values of relative biological effectiveness (RBE) for fast neutrons if compared with their parent cell lines. The other lines of human ataxia-telangiectasia fibroblasts, irs 1, irs 2, irs 3 and irs1SF cells, which were also radiosensitive but known as proficient in dsb repair, showed moderated RBEs. Dsb repair deficient mutants showed low RBE values for heavy ions. These experimental findings suggest that the DNA repair system does not play a major role against the attack of high linear energy transfer (LET) radiations. Therefore, we hypothesize that a main cause of cell death induced by high LET radiations is due to non-reparable dsb, which are produced at a higher rate compared to low LET radiations.     

Austrian dose measurements onboard space station MIR and the International Space Station--overview and comparison.

The Atominstitute of the Austrian Universities has conducted various space research missions in the last 12 years in cooperation with the Institute for Biomedical Problems in Moscow. They dealt with the exact determination of the radiation hazards for cosmonauts and the development of precise measurement devices. Special emphasis will be laid on the last experiment on space station MIR the goal of which was the determination of the depth distribution of absorbed dose and dose equivalent in a water filled Phantom. The first results from dose measurements onboard the International Space Station (ISS) will also be discussed. The spherical Phantom with a diameter of 35 cm was developed at the Institute for Biomedical Problems and had 4 channels where dosimeters can be exposed in different depths. The exposure period covered the timeframe from May 1997 to February 1999. Thermoluminescent dosimeters (TLDs) were exposed inside the Phantom, either parallel or perpendicular to the hull of the spacecraft. For the evaluation of the linear energy transfer (LET), the high temperature ratio (HTR) method was applied. Based on this method a mean quality factor and, subsequently, the dose equivalent is calculated according to the Q(LET infinity) relationship proposed in ICRP 26. An increased contribution of neutrons could be detected inside the Phantom. However the total dose equivalent did not increase over the depth of the Phantom. As the first Austrian measurements on the ISS dosimeter packages were exposed for 248 days, starting in February 2001 at six different locations onboard the ISS. The Austrian dosimeter sets for this first exposure on the ISS contained five different kinds of passive thermoluminescent dosimeters. First results showed a position dependent absorbed dose rate at the ISS.     

任意波发生器静态特性的评价

介绍了任意波发生器的主要静态特性指标、校准方法及实现过程。通过一组实验．获得了实际校准结果，并对校准中需要注意的问题进行了讨论。所述方法涉及的静态特性内容比较全面。具有足够的测量准确度、分辨力和稳定性。可用于任意波发生器的静态指标评价和计量。     

稠密颗粒增强复合材料应变分布规律和刚度张量

针对高体积份数、随机分布、等轴状颗粒增强复合材料 ,研究了材料的应变分布规律 ,给出了基体和增强体应变平均值与材料微观结构参数之间的定量关系。结果表明 ,除应变平均值外 ,应变涨落是影响刚度张量的另一个重要因素 ,研究了应变涨落与材料微观结构参数之间的关系 ,并推导出了复合材料的刚度张量。与实验结果和以往的理论比较 ,预测结果与实验结果吻合良好     

Carbon dioxide and oxygen budgets of a plant cultural system in a CELSS--a case of cultivation of lettuce and turnips.

In order to collect basic data about CO2 and O2 budgets of a plant cultural system in a CELSS, the variation of the CO2 absorption rates of lettuce and turnips were observed during the growing period, under different conditions. The O2 release rates were deduced from the CO2 absorption rates multiplied by 32/44. As a result, when the light intensity, the photoperiod and the atmospheric CO2 concentration increased, the rates also increased. The effects on the turnips were more significant than those on the lettuce. Turnips at 310 micromoles/m2/s of PPFD, 24 hours of photoperiod and 1100 ppm of CO2 concentration grew most actively in the present experimental conditions. One turnip absorbed 32.3 g CO2 and released 23.5 g O2 for 6 days between 24 days and 30 days after sowing.     

How Operational Oceanography Can Benefit from Dynamic Topography Estimates as Derived from Altimetry and Improved Geoid

With a precise geoid, GOCE will allow an estimation of absolute dynamic topography from altimetry. The projected benefits to operational oceanography and its applications are analyzed herein. After a brief overview of operational oceanography, we explain how the new geoids will be used in the future to improve real time altimeter products and to better constrain modelling and data assimilation systems. A significant impact is expected both for mesoscale (e.g. better estimations and forecasts of currents for pollution monitoring, marine safety, offshore industry) and climate (better initialization of coupled ocean/atmosphere models) applications. This revised version was published online in August 2006 with corrections to the Cover Date.     

Real-Time Specifications of the Geospace Environment

We report the recent progress in our joint program of real-time mapping of ionospheric electric fields and currents and field-aligned currents through the Geospace Environment Data Analysis System (GEDAS) at the Solar-Terrestrial Environment Laboratory and similar computer systems in the world. Data from individual ground magnetometers as well as from the solar wind are collected by these systems and are used as input for the KRM and AMIE magnetogram-inversion algorithms, which calculate the two-dimensional distribution of the ionospheric parameters. One of the goals of this program is to specify the solar-terrestrial environment in terms of ionospheric processes, providing the scientific community with more than what geomagnetic activity indices and statistical models provide. This revised version was published online in August 2006 with corrections to the Cover Date.