In this paper, we reconstruct the finite energy force-free magnetic field of the active region NOAA 8100 on 4 November 1997
above the photosphere. In particular, the 3-D magnetic field structures before and after a 2B/X2 flare at 05:58 UT in this
region are analyzed. The magnetic field lines were extrapolated in close coincidence with the Yohkoh soft X-ray (SXR) loops accordingly. It is found that the active region is composed of an emerging flux loop, a complex loop
system with differential magnetic field shear, and large-scale, or open field lines. Similar magnetic connectivity has been
obtained for both instants but apparent changes of the twisting situations of the calculated magnetic field lines can be observed
that properly align with the corresponding SXR coronal loops. We conclude that this flare was triggered by the interaction
of an emerging flux loop and a large loop system with differential magnetic field shear, as well as large-scale, or open field
lines. The onset of the flare was at the common footpoints of several interacting magnetic loops and confined near the footpoints
of the emerging flux loop. The sheared configuration remained even after the energetic flare, as demonstrated by calculated
values of the twist for the loop system, which means that the active region was relaxed to a lower energy state but not completely
to the minimum energy state (two days later another X-class flare occurred in this region). 相似文献
A model based on that of Kishi et al. (2001) has been extended to 15 compartments including silicon and carbon cycles. This model was applied to Station A7 off
Hokkaido, Japan, in the Northwestern Pacific. The model successfully simulated the observations of: 1. a spring bloom of diatoms;
2. large seasonal variations of nitrate and silicate concentrations in the surface water; and 3. large inter-annual variations
in chlorophyll-a. It also reproduced the observed features of the seasonal variations of carbon dioxide partial pressure (pCO2)—a peak in pCO2 in winter resulting from deep winter convection, a rapid decrease in pCO2 as a result of the spring bloom, and an almost constant pCO2 from summer through fall (when the effect of increasing temperature cancels the effect of biological production). A comparison
of cases with and without silicate limitation shows that including silicate limitation in the model results in: 1. decreased
production by diatoms during summer; and 2. a transition in the dominant phytoplankton species, from diatoms to other species
that do not take up silicate. Both of these phenomena are observed at Station A7, and our results support the hypothesis that
they are caused by silicate limitation of diatom growth.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
Rebuilding of victims' livelihoods was a crucial issue in the restoration process in the1995 Hanshin-Awaji Earthquake Disaster. Housing damage assessment influencedmost of the rebuilding of the livelihood in the long term, because the Victim Certificatesissued by the local governments based on the results of the Housing damage assessmentwas required to receive most of the individual assistance measures. In the process ofHousing damage assessment, many complex problems arose, leading to extensivework on the part of the disaster responders. Consequently, a considerable number ofvictims were dissatisfied with the assessment and applied for a resurvey. Due to a floodof requests for resurvey, disaster responders had to work on damage assessment, leavingrelief activities aside.In order to facilitate Housing damage assessment, this paper discusses thefollowing five points: (1) the processes and the problems of assessments performedin the Hanshin-Awaji Earthquake Disaster, (2) the changes in the nature of informationneeded by the victims, (3) the improvements over the present damage assessment, (4)the housing situation in Japan, and (5) the international situation on damage assessment.It is obvious from the results that a poor damage assessment system and the size ofthe disaster produced a very large work load. Differences in appreciation among theinvestigators also contributed to unfair assessments and led to the victims beingincreasingly dissatisfied by the survey results. Finally, a design concept for acomprehensive damage assessment system, which has been derived from theabove five points, is proposed for post-disaster management. 相似文献
Lateritic Ni ore mined in the Rio Tuba Mine, Philippines, derived from ultramafic rock by tropical intense weathering, is generally composed of two accumulated zones, an upper laterite zone and a lower saprolite zone. These two zones are very different in appearance, mineral assemblage, chemical composition, and in other ways. A transitional zone may be seen between the upper and lower zones, but it does not develop to any appreciable thickness. Although serpentine and goethite are still predominant in the constituent minerals, other clay minerals are increasing.
The transitional zone may be subdivided into three groups based on chemical composition. The behaviour of the chemical composition in this horizon indicates a complicated process of component transportation under the weathering process.
In the ore, chemical components are closely related in particle size of constituent minerals. In the laterite - transitional - saprolite sequence, a common variation range and tendency in chemical composition for each particle size can be seen. However, taking samples with the same particle size the chemical composition obviously differed, representing the characteristics of the components for each zone.
Concerning the correlation coefficient of the chemical components of each zone, a somewhat different inter-component relationship can be seen in these zones. These differences of correlation suggest the different complicated lateritized conditions under which they are formed. 相似文献
We have constructed a large, mosaic CCD camera called MOA-cam2 which has 4096 × 6144-pixelsto search for gravitational microlensing events. MOA-cam2 has three4096 × 2048-pixel SITe CCD chips, which have a very high quantum efficiency (nearly 80% in the wave region 500 to 800 nm),and three buttable sides. We have placed the threechips side by side with 100 m dead space. MOA-cam2 has been installed on the 61 cm Boller and Chivens telescope of the MOA collaboration at the Mt. John University Observatory (MJUO) in NewZealand since July 1998. The field coverage is 0.92° × 1.38° per exposure. The technical details of MOA-cam2 and the first images obtained with the Boller and Chivens telescope are presented. MOA-cam2 introduces a second phase of research on gravitational microlensing by the MOA collaboration. 相似文献
Bodies located in outdoor environments are radiatively heated in the daytime and cooled at night. Convective heat transfer is subsequently activated between the body surface and the surrounding air. To investigate these heat-exchange processes, we developed a new apparatus, referred to as a “polyethylene chamber”, for use in physical model experiments. The chamber is a 1.51-m-long tube with the ends serving as the air inlet and outlet, and is ventilated in the longitudinal direction by using an exhaust fan. The measurement section of the chamber is open but otherwise the device is covered with 0.02-mm-thick polyethylene film. Because such thin polyethylene film transmits approximately 85 % of both shortwave and longwave radiation, the model surface in the chamber is exposed to a radiation level almost equivalent to the outdoor radiation level. For example, at night the surface of the model is cooled by radiation, and subsequently, the air inside the chamber is cooled by the surface. Consequently, the outlet air temperature becomes lower than the inlet air temperature. The use of this temperature difference between the air inlet and outlet, together with other heat balance components, is a unique approach to the chamber technique for evaluating the heat exchange rate at a model’s surface. This report describes the design and heat balance of the chamber, and compares the heat-balance-based approach with another approach based on the radiation–convection balance on the model surface. To demonstrate the performance of the polyethylene chamber, two chambers were exposed to outdoor radiation on a clear night; one contained a leaf model. Air and surface temperatures were measured and the convective heat flux at the surfaces of the model and floor surface were calculated from the heat balance components of the chambers by assuming steady-state heat transfer. The fluxes agreed closely with those obtained from the radiation–convection balance at the model or floor surface. The results also clearly showed that the air flowing in the polyethylene chamber was cooled more efficiently when the model surface was installed in the chamber, even though the model surface temperature was high. 相似文献
Simultaneous spaced measurements of medium-latitude VLF/ELF emissions were carried out during the three northern winters from 1976 to 1979. The experiment was making use of two different kinds of direction-finding systems (a field-analysis method and a goniometer network) at two stations in Europe, namely Brorfelde in Denmark (L = 2.9) and Chambron-la-Foret in France (L = 1.9); this enabled us to locate the ionospheric exit regions of emissions over a wide range of L-values up to and beyond 4.0, the average plasmapause location. In order to study the time delay in the temporal evolution of VLF emissions or the longitudinal drift of the emissions, observations from the Moshiri Observatory in Japan, widely separated in longitude, are also used. The overall system of the VLF equipment installed at the three stations is described. Then we present the VLF/ELF data of good quality obtained during the final year's campaign (Nov. 1978–Feb. 1979). By making use of the direction-finding data, we were able to classify the observed emissions into several categories, and some early results for some of the emissions are presented. 相似文献