无机水合盐相变储能材料的过冷及相分离研究进展

无机水合盐是一类重要的相变储能材料,具有使用范围广、导热系数大、相变潜热大、毒性小、价格便宜等优点。但这类材料在使用过程中易出现"过冷"及"相分离"现象,严重制约了其在实际中的应用。介绍了通过添加成核剂和增稠剂等几种解决无机水合盐相变储能材料使用过程中"过冷"及"相分离"的新方法,并对今后的研究提出了几点建议。     

盐水体系热力学平衡态和非平衡态相图

在对海水Ｎａ＋、Ｋ＋、Ｍｇ（２＋）／／ＣＩ－、ＳＯ４（２－）－Ｈ２Ｏ体系在２５℃时或室温条件下采用合成复体法得到的平衡溶解度相图，蒸发结晶方式得到的蒸发相和采用过饱和溶液封闭静置结晶法得到的过饱和区相图进行对比分析，把它们划分成两种类型，热力学平衡态和非平衡态相图。对这两类相图关系进行探讨基础上认为，热力学非平衡相图主要是由于同一种盐在水溶液中是双粒子形式共存而引起过饱和溶解度现象所致。     

A post-Calumet shoreline along southern Lake Michigan

The southern shore of Lake Michigan is the type area for many of ancestral Lake Michigan’s late Pleistocene lake phases, but coastal deposits and features of the Algonquin phase of northern Lake Michigan, Lake Huron, and Lake Superior are not recognized in the area. Isostatic rebound models suggest that Algonquin phase deposits should be 100 m or more below modern lake level. A relict shoreline, however, exists along the lakeward margin of the Calumet Beach that was erosional west of Deep River and depositional east of the river. For this post-Calumet shoreline, the elevation of basal foreshore deposits east of Deep River and the base of the scarp west of Deep River indicate a slightly westward dipping water plane that is centered at ∼184 m above mean sea level. Basal foreshore elevations also indicate that lake level fell ∼2 m during the development of the shoreline. The pooled mean of radiocarbon dates from the surface of the peat below post-Calumet shoreline foreshore deposits indicate that the lake transgressed over the peat at 10,560 ± 70 years B.P. Pollen assemblages from the peat are consistent with this age. The elevation and age of the post-Calumet shoreline are similar to the Main Algonquin phase of Lake Huron. Recent isostatic rebound models do not adequately address a high-elevation Algonquin-age shoreline along the southern shore of Lake Michigan, but the Goldthwait (1908) hinge-line model does.     

沙源供给条件对风沙流结构的影响

 针对风沙运动的气固两相流特点,利用FLUNET 软件,对不同沙源供给条件下各种床面的风沙积蚀平衡进行了数值模拟,给出了风速分布和沙粒体积分数随沙源供给条件和下垫面变化的线图,比较了流动边界条件对流场的影响。计算结果揭示了风沙运动中沙粒的体积浓度分布在风速变化和床面形态变化下的变化规律,为沙漠化的防治和理论研究提供了基础。     

ScS wave splitting of deep earthquakes around Japan

ScS wave splitting of five deep earthquakes in subduction zones near Japan is investigated using horizontal seismograms recorded al JMA stations. For each earthquake, we clearly observe uniform ScS wave splitting in all stations over Japan, especially for the events located south of Honshu in 1982, 1984 and 1993. However, the directions of fast-polarized waves of these events differed by a maximum of about 50° from one another. The orientation of fast-polarized waves in the 1982 event was NNW-SSE; those in the two later events WNW-ESE. We also recognize this discrepancy in the results of the analysis of the 1971 Sea of Okhotsk event reported by Fukao (1984). The Sakhalin Islands event in 1990 reveals a linear particle motion without such a change in direction of the second arrivals, implying no anisotropy. These observations are interpreted as indicating an anisotropic region within the slab near the earthquake sources but not beneath the receivers, since the orientations of fast-polarized waves recorded at each station are not common to all the earthquakes. Furthermore, we consider that anisotropy exists non-uniformly within the slab. The event in 1982, which occurred in almost the same area as those in 1984 and 1993, showed a fast direction different from the events in 1984 and 1993. The 1982 event was 179 km deep, but the two later events were at 398 km and 360 km, respectively. The fast direction observed from the 1982 event is parallel to the fossil plate motion, whereas those from the events in 1984 and 1993 are parallel to the compression axis within the subducting slab. The depth of 400 km is a phase boundary, where olivine changes to β spinel. We consider that the most likely cause of the change in anisotropy direction is the re-orientation of crystals associated with the phase change of olivine to β spinel due to subduction of the slab.     

干涉SAR的二维相位解缠算法研究

相位解缠是干涉合成孔径雷达 (INSAR)应用的重要步骤之一。本文通过一定的实验研究 ,对比分析了现有的几种主要的相位解缠算法的原理和特点。路径积分算法的局域算子和最小二乘算法的全局算子是这两类解缠算法的本质特征。而各种不同的算法对不同的数据也各自有其特定的适宜性 ,算法的选择应该视实际数据的特点而定。     

基于瞬时相位的BPSK信噪比估计算法

通过对加性高斯白噪声条件下正弦型信号瞬时相位分布情况进行研究,提出了一种新的BPSK（Binary Phase Shift Keying）信噪比估计方法．含噪信号瞬时相位的方差与信噪比之间存在近似线性的一一对应关系,以此为基础通过将含噪信号的估计方差与理论值相比较获得信噪比估计值．该方法直接对基带过采样信号进行处理,不需要事先进行符号定时与同步．使用计算机仿真测试了算法的估计性能,并与高阶累积量方法和子空间分解方法进行了比较,结果表明该算法具有更高的估计精度．     

美国工业化阶段的历史评估

工业化是通向现代化社会的基本途径。美国是人类历史上最大的工业化国家,曾拥有最为完整的工业体系和最为规范的工业化路径,其工业化经验对同为大国的中国具有一定的借鉴意义。本文依据发展经济学结构学派的工业化阶段理论,主要采用部门结构和人均收入的动态指标,对美国工业化过程的起讫时间进行了界定,然后将该过程划分为轻工业化、重工业化和技术集约化三个基本阶段,并根据产业重心不同将重工业化阶段分解为前后两个半段,并给出了每一阶段的具体时间范围。这种研究有助于从整体上把握美国工业化的全貌,并展现出美国经济崛起的历史轨迹。     

On Phase Shifts In Periodic Well Fluctuations

Summary. For the case of a well completely penetrating a confined aquifer of infinite extent, an analysis is made of the flow processes in the well-aquifer system due to periodic pressure variations like earth tides and barometric tides. It is shown that the earth tides lead to well fluctuations with a negative phase difference (phase lag), while the barometric tides cause well fluctuations with a positive phase difference (phase advance).
In both cases the amplitudes and phases of the well fluctuations depend on frequency and are therefore different for the individual components of the tidal spectra. These frequency characteristics need to be studied more carefully than is the case now. A schematic model of a device is described that could not only be used for this purpose, but also for the determination of the specific storage S _s and the conductivity k. the method would be closely related to the well-known slug or bail tests.     

Na~ /Cl~-,B_4O_7~(2-)-H_2O体系在28℃与35℃时介稳相平衡研究

采用等温蒸发法研究了Na /Cl-,B4O72--H2O体系28℃与35℃介稳相平衡及溶液的物化性质(密度、折光率),绘制了相应的介稳相图。该介稳体系属简单共饱和型,相图由两条溶解度曲线构成,分别对应于Na2B4O7.10H2O和NaCl相区。用经验公式计算了该体系在相应温度下的密度、折光率,与实验测定结果吻合较好。     

Na~ /Cl~-,B_4O_7~(2-)-H_2O体系在28℃与35℃时介稳相平衡研究

采用等温蒸发法研究了Na+/Cl-,B4O2-7-H2O体系28 ℃与35 ℃介稳相平衡及溶液的物化性质(密度、折光率),绘制了相应的介稳相图.该介稳体系属简单共饱和型,相图由两条溶解度曲线构成,分别对应于Na2B4O7·10H2O和NaCl相区.用经验公式计算了该体系在相应温度下的密度、折光率,与实验测定结果吻合较好.     

Material versus isobaric internal boundaries in the Earth and their influence on postglacial rebound

Most previous earth models used to calculate viscoelastic relaxation after the removal of the Late Pleistocene ice loads implicitly assume that there is no exchange of mass across the mantle density discontinuities on periods of tens of thousands of years (the material boundary formulation). In the present study, simple incompressible models are used to determine the Earth's behaviour in the case where the density discontinuity remains at a constant pressure rather than deforming with the material (the isobaric boundary formulation). The calculation of the movement of the boundary is more rigorous than in earlier studies and uses the local incremental pressure calculated at the depth of the boundary and allows for the vertical deformation caused by the change in volume as material changes phase. It is shown that the buoyancy modes associated with the density discontinuities decrease in strength and increase in relaxation time analogous to what results when the density contrast is reduced. Also, two viscoelastic modes arise from an isobaric boundary, which is also predicted when there is a contrast in rigidity or viscosity across a material boundary. The difference in predicted radial deformation between the isobaric boundary model and the material boundary model is largest for long-wavelength loads for which the material incremental pressure at depth is largest. If the isobaric boundary model is appropriate for the treatment of the mineral phase changes in the mantle on glacial rebound timescales, then previous inferences of the deep-mantle to shallow-mantle viscosity ratio based on large-scale deformation (spherical harmonic degree < 10) of the Earth and including data from the early part of the glacio-isostatic uplift are too small.