Atmospheric entry profiles from the Mars Exploration Rovers Spirit and Opportunity

Accelerometer measurements made by Spirit and Opportunity during their entries through the martian atmosphere are reported. Vertical profiles of atmospheric density, pressure, and temperature with sub-km vertical resolution were obtained using these data between 10 and 100 km. Spirit's temperature profile is ∼10 K warmer than Opportunity's between 20 and 80 km. Unlike all other martian entry profiles, Spirit's temperature profile does not contain any large amplitude, long wavelength oscillations and is nearly isothermal below 30 km. Opportunity's temperature profile contains a strong inversion between 8 and 12 km. A moderate dust storm, which occurred on Mars shortly before these two atmospheric entries, may account for some of the differences between the two profiles. The poorly known angle of attack and unknown wind velocity may cause the temperature profiles to contain errors of tens of Kelvin at 10 km, but these errors would be an order of magnitude smaller above 30 km. On broad scales, the two profiles are consistent with Mars Global Surveyor Thermal Emission Spectrometer (TES) pressure/temperature profiles. Differences exist on smaller scales, particularly associated with the near-isothermal portion of Spirit's profile and the temperature inversion in Opportunity's profile.     

协调决策表的规则提取

对数据的性质、数据之间的关系进行了讨论，并由此对决策表进行了分类。研究了协调决策表所需要的必要的数据个数，这对数据采集有着实际的指导意义和经济意义。讨论了协调决策表的数据约简，并证明其不影响进一步的属性约简和规则提取。基于数据的协调性，对协调决策表的属性约简进行了研究，并提出了一种规则提取方法。最后，用实例验证了该方法的有效性。     

Partial Reduction in the N-Body Planetary Problem using the Angular Momentum Integral

We present a new set of variables for the reduction of the planetary n-body problem, associated to the angular momentum integral, which can be of any use for perturbation theory. The construction of these variables is performed in two steps. A first reduction, called partial is based only on the fixed direction of the angular momentum. The reduction can then be completed using the norm of the angular momentum. In fact, the partial reduction presents many advantages. In particular, we keep some symmetries in the equations of motion (d'Alembert relations). Moreover, in the reduced secular system, we can construct a Birkhoff normal form at any order. Finally, the topology of this problem remains the same as for the non-reduced system, contrarily to Jacobi's reduction where a singularity is present for zero inclinations. For three bodies, these reductions can be done in a very simple way in Poincaré's rectangular variables. In the general n-body case, the reduction can be performed up to a fixed degree in eccentricities and inclinations, using computer algebra expansions. As an example, we provide the truncated expressions for the change of variable in the 4-body case, obtained using the computer algebra system TRIP.     

Radon reduction in homes constructed on saprolite in the Central Appalachians

 A 3-year study of indoor radon in more than 1000 homes in northern Virginia and southern Maryland was conducted using 3-month exposure alpha-track monitors. In a study set of 200 homes, first-floor indoor radon concentrations, which most closely approximates home exposure levels, averaged slightly more than 3 pCi/l. In a study set of 100 homes, sub-slab ventilation was used to reduce indoor radon concentrations. Interest in remediation was related to public perception of the hazardous nature of radon; people living in homes with indoor radon measurements of more than 4 pCi/l were more likely to participate in the remediation phase of the project. Sub-slab ventilation was successful in more than 90% of the homes in reducing indoor radon from concentrations as high as 30 pCi/ to less than 4 pCi/l, at least for the entire year of post-remediation radon measurements. Received: 29 February 1996 · Accepted: 29 May 1996     

光子计数资料处理方法的比较

本文通过对天体测量仪器光子计数模拟资料的处理,比较了13种不同的平滑模型和两种定心算法对最终精度的影响;提出了利用频率域滤波和修正矩方法相结合的最佳处理方法;并对比较结果进行了多方面的讨论。     

AIPS对综合孔径展源的图象处理

本文介绍了用美国国立射电天文台图象处理软件系统—AIPS对综合孔径VLA观测数据的处理方法,特别是对展源,要得到高质量的图象,在编辑及成图中要注意的事项。作者根据自己的实际工作,总结了用AIPS进行图象处理的经验。     

The U.S. National Tsunami Hazard Mitigation Program: A Successful State–Federal Partnership

The U.S. National Tsunami Hazard Mitigation Program (NTHMP) is a State/Federal partnership created to reduce tsunami hazards along U.S. coastlines. Established in 1996, NTHMP coordinates the efforts of five Pacific States: Alaska, California, Hawaii, Oregon, and Washington with the three Federal agencies responsible for tsunami hazard mitigation: the National Oceanic and Atmospheric Administration (NOAA), the Federal Emergency Management Agency (FEMA), and the U.S. Geological Survey (USGS). In the 7 years of the program it has, 1. established a tsunami forecasting capability for the two tsunami warning centers through the combined use of deep ocean tsunami data and numerical models; 2. upgraded the seismic network enabling the tsunami warning centers to locate and size earthquakes faster and more accurately; 3. produced 22 tsunami inundation maps covering 113 coastal communities with a population at risk of over a million people; 4. initiated a program to develop tsunami-resilient communities through awareness, education, warning dissemination, mitigation incentives, coastal planning, and construction guidelines; 5. conducted surveys that indicate a positive impact of the programs activities in raising tsunami awareness. A 17-member Steering Group consisting of representatives from the five Pacific States, NOAA, FEMA, USGS, and the National Science Foundation (NSF) guides NTHMP. The success of the program has been the result of a personal commitment by steering group members that has leveraged the total Federal funding by contributions from the States and Federal Agencies at a ratio of over six matching dollars to every NTHMP dollar. Twice yearly meetings of the steering group promote communication between scientists and emergency managers, and among the State and Federal agencies. From its initiation NTHMP has been based on the needs of coastal communities and emergency managers and has been results driven because of the cycle of year-to-year funding for the first 5 years. A major impact of the program occurred on 17 November 2003, when an Alaskan tsunami warning was canceled because real-time, deep ocean tsunami data indicated the tsunami would be non-damaging. Canceling this warning averted an evacuation in Hawaii, avoiding a loss in productivity valued at $68M.     

Isotopic evidence of TSR origin for natural gas bearing high H<Subscript>2</Subscript>S contents within the Feixianguan Formation of the northeastern Sichuan Basin,southwestern China

The northeastern area of Sichuan Basin, southwestern China, is the area with the maximal reserve of natural gas containing higher hydrogen sulphide (H₂S) that has been found among the petroliferous basins of China, with the proven and controlled gas reserve of more than 200 billion cubic meters. These gas pools, with higher H₂S contents averaging 9%, some 17%, are mainly distributed on structural belts of Dukouhe, Tieshanpo, Luojiazhai, Puguang, etc., while the oolitic-shoal dolomite of the Triassic Feixianguan Fm. (T₁f) is the reservoir. Although many scholars regard the plentiful accumulation of H₂S within the deep carbonate reservoir as the result of Thermochemical Sulfate Reduction (TSR), however, the process of TSR as well as its residual geological and geochemical evidence is still not quite clear. Based on the carbon isotopic analysis of carbonate strata and secondary calcite, etc., together with the analysis of sulfur isotopes within H₂S, sulphur, gypsum, iron pyrites, etc., as well as other aspects including the natural gas composition, carbon isotopes of hydrocarbons reservoir petrology, etc., it has been proved that the above natural gas is a product of TSR. The H₂S, sulphur and calcite result from the participation of TSR reactions by hydrocarbon gas. During the process for hydrocarbons being consumed due to TSR, the carbons within the hydrocarbon gas participate in the reactions and finally are transferred into the secondary calcite, and become the carbon source of secondary calcite, consequently causing the carbon isotopes of the secondary calcite to be lower (−18.2‰). As for both the intermediate product of TSR, i.e. sulfur, and its final products, i.e. H₂S and iron pyrites, their sulfur elements are all sourced from the sulfate within the Feixianguan Fm. During the fractional processes of sulfur isotopes, the bond energy leads to the ³²S being released firstly, and the earlier it is released, the lower δ ³⁴S values for the generated sulphide (H₂S) or sulfur will be. However, for the anhydrite that participates in reactions, the higher the reaction degree, the more ³²S is released, while the less ³²S remains and the more δ ³⁴S is increased. The testing results have proved the process of the dynamic fractionation of sulfur isotopes.     

中国气象频道广西本地发展策略探讨

通过对中国气象频道本地发展现状和全国各地气象频道发展现状进行分析,提出中国气象频道本地发展策略:通过积极争取政府及相关部门支持广西应急气象频道的建设,建立部门联动的合作机制;推进业务服务体系建设,提升频道综合业务能力;完善广西应急气象频道节目体系,切实提升服务水平;建立健全系统业务流程,大力推进人才体系建设,从而把广西应急频道打造成为综合防灾减灾频道。