Analysis of a microwave backscattering mechanism from a small urban area imaged with SIR-C     

Fujita  M. Miho  Y. 《Geoscience and Remote Sensing Letters, IEEE》2006,3(1):10-14

We analyzed the Spaceborne Imaging Radar C (SIR-C) imagery of a small urban area to characterize backscattering mechanisms. The results were compared with the building density so that we could relate the polarimetric backscattering characteristics with urban structures. Relative contributions of odd-bounce, double-bounce, and cross-polarized scatterings were evaluated as a function of the building density for small and large incidence angles. Their behaviors were characterized with respect to urban structures at small and large incidence angles.  相似文献   

Temperature variation of elastic constants of quartz across the α - β transition     

Ichiro Ohno  Kazumi Harada  Chihiro Yoshitomi 《Physics and Chemistry of Minerals》2006,33(1):1-9

The α − β transition of quartz was successfully observed with using a single sample by means of the rectangular parallelepiped resonance (RPR) method. An oriented rectangular parallelepiped of α-quartz single crystal was prepared and the resonant frequencies of 30–11 vibrational modes were measured from room temperature to 700°C. The softening of quartz crystal was observed as the significant reduction of resonant frequencies near the α–β transition. The present study is the first application of the RPR method to the study of phase transition. The complete set of elastic constants of α- and β-quartz were determined as a function of temperature by the least-squares inversion of the measured frequency data obtained by a single run. This is a merit yielded by the RPR method. It is shown near the α − β transition in both α- and β-quartz that the elastic parameters decrease proportionally to |T−T ₀|⁻ⁿ , where T is temperature and T ₀ is the transition temperature, 573.0°C for α-quartz and 574.3°C for β-quartz. It was also seen that linear incompressibilities K ₁ = (C ₁₁ +C ₁₂ +C ₁₃)/3 and K ₃ = (C ₃₃ +2C ₁₃)/3 decrease rapidly toward the transition, whereas, shear moduli C ₄₄, C _S1 = (C ₁₁ +C ₃₃ -2C ₁₃)/4 and C _S3 = (C ₁₁ -C ₁₂)/2 = C ₆₆ decrease only slightly. The shear modulus C _S3 = C ₆₆ increased slightly in α-quartz. The elastic properties of isotropic aggregate of quartz were calculated, and it is shown that the longitudinal wave velocity significantly decreases at the α − β transition, whereas, the shear wave velocity decreases only slightly.  相似文献   

Strontium incorporation into calcite generated by bacterial ureolysis     

Yoshiko Fujita  George D Redden  Marnie M Cortez  Robert W Smith 《Geochimica et cosmochimica acta》2004,68(15):3261-3270

Strontium incorporation into calcite generated by bacterial ureolysis was investigated as part of an assessment of a proposed remediation approach for ⁹⁰Sr contamination in groundwater. Urea hydrolysis produces ammonium and carbonate and elevates pH, resulting in the promotion of calcium carbonate precipitation. Urea hydrolysis by the bacterium Bacillus pasteurii in a medium designed to mimic the chemistry of the Snake River Plain Aquifer in Idaho resulted in a pH rise from 7.5 to 9.1. Measured average distribution coefficients (D_EX) for Sr in the calcite produced by ureolysis (0.5) were up to an order of magnitude higher than values reported in the literature for natural and synthetic calcites (0.02-0.4). They were also higher than values for calcite produced abiotically by ammonium carbonate addition (0.3). The precipitation of calcite in these experiments was verified by X-ray diffraction. Time-of-flight secondary ion mass spectrometry (ToF SIMS) depth profiling (up to 350 nm) suggested that the Sr was not merely sorbed on the surface, but was present at depth within the particles. X-ray absorption near edge spectra showed that Sr was present in the calcite samples as a solid solution. The extent of Sr incorporation appeared to be driven primarily by the overall rate of calcite precipitation, where faster precipitation was associated with greater Sr uptake into the solid. The presence of bacterial surfaces as potential nucleation sites in the ammonium carbonate precipitation treatment did not enhance overall precipitation or the Sr distribution coefficient. Because bacterial ureolysis can generate high rates of calcite precipitation, the application of this approach is promising for remediation of ⁹⁰Sr contamination in environments where calcite is stable over the long term.  相似文献   

Polychlorinated biphenyl (PCB) concentrations and congener composition in masu salmon from Japan: A study of all 209 PCB congeners by high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS)     

Reiko Matsumoto  Nguyen Phuc Cam Tu  Shinsuke Haruta  Masahide Kawano  Ichiro Takeuchi 《Marine pollution bulletin》2014

We collected two subspecies of masu salmon: Oncorhynchus masou masou from four localities (southern Sea of Japan northward to Hokkaido) and O. masou ishikawae from upstream from Ise Bay close to a heavy industrial area. All 209 PCB congeners were analyzed using HRGC/HRMS. PCA ordination of congener concentrations divided data into three groups: (i) ssp. masou from Hokkaido, (ii) ssp. masou from the other regions and (iii) ssp. ishikawae. The highest ∑ PCB concentration (40.39 ng/wet wt) was in ssp. ishikawae followed by ssp. masou from southern waters; however the TEQ_{dioxin-like PCBs} was highest in ssp. masou from southern water (1.96 pg-TEQ_{dioxin-like PCBs}/g wet wt.) due to the high proportion of congener #126 in its complement (#126 has the highest toxic equivalency factor among congeners). There is likely a contamination source offshore in the southern Sea of Japan and/or along the migratory route of ssp. masou.  相似文献   

Trace element concentrations in barramundi (Lates calcarifer) collected along the coast of Vietnam     

Nguyen Phuc Cam Tu  Nguyen Ngoc Ha  Shinsuke Haruta  Ichiro Takeuchi 《Marine pollution bulletin》2014

We determined concentrations of 23 trace elements (TEs), and stable carbon and nitrogen isotope (δ¹³C and δ¹⁵N) signatures in barramundi (Lates calcarifer) specimens collected along the coast of Vietnam in the Northern (NCZ), Central (CCZ) and Southern (SCZ) zones in the period 2007–2010. A combination of δ¹³C and δ¹⁵N signatures provided insight into ontogenetic shifts in barramundi foraging choices. There were clear zone-dependent differences in Mn, As, Sr and Tl concentrations; levels of Tl were highest in the NCZ, As in the CCZ, and Mn and Sr in the SCZ. Lowest concentrations of Rb occurred in the NCZ, Bi was lowest in the CCZ, and Cd and Cs were lowest in the SCZ. δ¹⁵N values significantly increased with increasing Zn, Se, Sn and Cs. Concentrations of TEs in barramundi from Vietnam were below worldwide guidelines for human consumption.  相似文献   

Subsurface hydrographic structures and the temporal variations of Aleutian eddies     

Rui Saito  Ichiro Yasuda  Kosei Komatsu  Hiromu Ishiyama  Hiromichi Ueno  Hiroji Onishi  Takeshi Setou  Manabu Shimizu 《Ocean Dynamics》2016,66(5):605-621

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Experiment and validation of numerical simulation of coupled thermal,hydraulic and mechanical behaviour in the engineered buffer materials     

Masakazu Chijimatsu  Tomoo Fujita  Akira Kobayashi  Masashi Nakano 《国际地质力学数值与分析法杂志》2000,24(4):403-424

Evaluation of the coupled heat transfer, water flow and stress changes in the engineered clay barrier is an important issue in the performance assessment of the high‐level radioactive waste disposal. To demonstrate the function of the engineered barrier system, the large‐scale experiment is conducted, which is called Big Bentonite facility (BIG‐BEN). The facility consists of an electric heater surrounded by glass beads, carbon steel overpack, buffer material and man‐made rock. The buffer is a mixture of bentonite and sand. The heater is operated at 0·8 kW. Water is injected from the interface between the buffer and the man‐made rocks at the pressure of 0·05 MPa. The duration of the experiment is 20 months. The change in temperature and swelling pressure are continuously monitored and gravimetric water content is measured by sampling. The coupled thermal, hydraulic and mechanical processes are simulated with a finite element code THAMES, which can simulate the fully coupled phenomena in the saturated and unsaturated clay under anisothermal condition. To examine the validity of the code, all the parameters used in the model are evaluated from the other laboratory tests. The simulated results are compared with the measured ones without calibration of the parameter values using the results from the BIG‐BEN experiment. It can be concluded that the changes in temperature and gravimetric water content within the buffer can be simulated reasonably well and that the mechanical effect such as swelling pressure is difficult to realize. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

白鱀豚哨叫声的研究   总被引：1，自引：0，他引：1  

王丁  王克雄  赤松友成  藤田薰 《海洋与湖沼》1999,30(4):349-354

于1996年1月,在中国科学院水生生物研究所白暨豚馆人工饲养池和湖北省石首市天鹅洲长江故道,使用频响范围分别为0－100kHz和0－16kHz的磁带记录系统,记录了一头成年雄性和一头成年雌性白暨豚的哨叫声。采用计算机信号分析系统详细分析了哨叫声的结构和声谱图,并与其它鲸类哨叫声进行比较。结果表明,白暨豚哨叫声的最大和最小频率平均值分别为5841Hz和4975Hz,频率变化幅度一般小于1000Hz。哨叫声平均持续时间为907ms。频率随时间变化不连续,且较平缓,起伏很少,有部分重叠现象。白暨豚哨叫声的结构与另一种淡水豚─—亚河豚相近,但相对于一些海洋性种类（如宽吻海豚）则呈现较大的差异,表现出对环境的高度适应性。  相似文献   

Thematic Section: Geological anatomy of East and South Asia: Paleogeography and paleoenvironments in Eastern Tethys (IGCP 516) Part 1     

Ken‐Ichiro Hisada  Graciano P. Yumul Jr 《Island Arc》2008,17(4):419-420

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Laboratory based continuous bedload monitoring in a model retention basin: Application of time domain reflectometry          下载免费PDF全文

Shusuke Miyata  Masaharu Fujita 《地球表面变化过程与地形》2018,43(9):2022-2030

In this study, we applied time domain reflectometry (TDR) to determine the deposition height and porosity of sediment at a fine spatiotemporal resolution, and developed a continuous bedload monitoring method that can be applied to pools in steep mountain rivers. The TDR monitoring system consisted of sensor probes, a cable tester, multiplexers and coaxial cables. When the embedded probes penetrated both water and sediment, the boundaries of the sediment and water were consistent with the transition points in the observed waveforms of each TDR measurement. A semi‐automatic analysis of the recorded TDR waveforms, which did not require calibration or parameter fitting, was conducted to establish continuous monitoring. In addition, a flume experiment was performed to test the monitoring system in a model retention basin connected to a flume, with sand of uniform grain size (1.4 mm diameter) supplied for 30 min. The sediment volume in the container representing the model basin was monitored using a load cell underlying the container and eight sensor probes, with a length of almost 0.27 m. The sediment thickness determined by the TDR indicated a gradual deposition, and was consistent with manual measurements. Despite a marginal overestimation of 13% for a sand feed of 30 kg, the sediment volume in the model retention basin and the bedload transport rate were successfully estimated. A combination of our monitoring system and other indirect methods, such as geophones, can potentially serve as useful tools for better understanding bedload transport processes in steep mountain streams. Copyright © 2018 John Wiley & Sons, Ltd.  相似文献