Microphysics: Equation of State

The equation of state is one of the three fundamental ingredients used to construct stellar models. The plasma of the interiors of stars such as the Sun is only slightly non-ideal. However, the extraordinary accuracy of the helioseismological data requires refined equations of state. It turned out to be necessary to include a Coulomb correction, commonly evaluated in the Debye-Hückel approximation. Higher-order non-ideal effects have implications as well, both for plasma physics and for solar physics. As a typical example, the recently studied thermodynamic consequence of excited states in compound particles is discussed. This effect is of considerable relevance in the helioseismic determination of the helium abundance in the solar convection zone. This revised version was published online in June 2006 with corrections to the Cover Date.     

Columbia: point of departure

The author provides a brief update of NASA safety management after the Columbia accident and the development of space transport systems after the Shuttle.     

汉堡之家:隐藏的能量

在2010年上海世博会上,汉堡将兴建一栋体现最高环保技术水平、融居住与工作功能于一身的示范性建筑——汉堡之家,其建筑设计风格融合了传统和现代的汉堡元素,堪称符合汉堡港口新城环保金奖标准的可持     

Energetics of reconnection: A reply

In this article we address several criticisms of Petschek-type reconnection models which have recently been raised by Heikkila. We discuss features of the time-dependent Petschek-type models in the context of the solar wind-magnetosphere interaction, and point out that such models can incorporate and reproduce observed features at the magnetopause, such as plasma jets and erosion of the current sheet. We argue that some of Heikkila's criticisms can be attributed to weaknesses in the analysis due to incomplete experimental information, rather than to flaws in the concept of reconnection per se; in this category we include the question of which instability leads to the localised breakup of the magnetopause current sheet. Other criticisms are based on an adherence to steady-state models, and cannot be sustained within the extended time-dependent theory. We discuss, for example, how the time-dependent model can provide a consistent picture of how energy from the incoming solar wind is transferred and converted as it enters the magnetosphere.     

VII: CLOSING SESSION: GOCE: ESA's First Earth Explorer Core Mission

This paper introduces the first ESA Core Earth Explorer mission, GOCE, in the context of ESA's Living Planet programme. GOCE will measure highly accurate, high spatial resolution differential accelerations in three dimensions along a well characterised orbit: the mission is planned for launch in early 2006. The mission objectives are to obtain gravity gradient data such that new global and regional models of the static Earth's gravity field and of the geoid can be deduced at length scales down to 100 km. These products will have broad application in the fields of geodesy, oceanography, solid-earth physics and glaciology. This revised version was published online in August 2006 with corrections to the Cover Date.     

Prefiltering: cascaded stages of decimation-by-two

A very efficient method of reducing the bandwidth of a sampled signal is presented. The method is implemented as a sequence of filtering and decimation stages, where the data rate is halved in each stage. Part of the efficiency is gained through the use of symmetrical linear-phase finite-duration impulse response filters, which have the added benefit that the operation is free of any phase distortion     

V: SEA LEVEL: Benefits of GRACE and GOCE to sea level studies

The recently published Third Assessment Reports of the Intergovernmental Panel on Climate Change have underlined the scientific interest in, and practical importance of past and potential future sea level changes. Space gravity missions will provide major benefits to the understanding of the past, and, thereby, in the prediction of future, sea level changes in many ways. The proposal for the GOCE mission described well the improvements to be expected from improved gravity field and geoid models in oceanography (for example, in the measurement of the time-averaged, or ‘steady state’, ocean surface circulation and better estimation of ocean transports), in geophysics (in the improvement of geodynamic models for vertical land movements), in geodesy (in positioning of tide gauge data into the same reference frame as altimeter data, and in improvement of altimeter satellite orbits), and possibly in glaciology (in improved knowledge of bedrock topography and ice sheet mass fluxes). GRACE will make many important steps towards these ‘steady state’ aims. However, its main purpose is the provision of oceanographic (and hydrological and meteorological) temporally-varying gravity information, and should in effect function as a global ‘bottom pressure recorder’, providing further insight into the 3-D temporal variation of the ocean circulation, and of the global water budget in general. This paper summaries several of these issues, pointing the way towards improved accuracy of prediction of future sea level change. This revised version was published online in August 2006 with corrections to the Cover Date.     

To the surface of Mars via Titan: : Reuse of Huygens software components on Beagle 2

‘Beagle 2’ is a Mars lander, which will be flown in 2003 as part of ESA's Mars Express mission. Like the Huygens probe to Titan, it is critically dependent on the correct functioning of on-board software to control its descent. Beagle 2 is a much lower cost mission and cannot afford to develop all of its software from scratch. How has the Huygens software been given a new lease of life on-board Beagle 2?     

Flares of August 1972: Analysis of dynamics

The optical observations and analyses of the flares of August 1972 are reviewed with emphasis on their dynamics. In particular, various assessments are made of possible quantitative interpretation of observed data. Specific topics considered are the storage and release of magnetic energy, triggering mechanisms, particle acceleration and magnetic field reconnection, and coronal and solar wind responses. Supplemental discussions on possible future direction of research are presented, illustrating the need for examination of the storage and release of flare energy in the lower solar atmosphere.On leave from the High Altitude Observatory.The National Center for Atmospheric Research is sponsored by the National Science Foundation.     

IV: GEODESY: Remarks on the Role of Height Datum in Altimetry-Gravimetry Boundary-Value Problems

The problem of global geoid determination is usually solved using satellite altimetry data on the oceans, together with an oceanographic model of sea surface topography, and gravity anomaly data on the continents. Such data, however, enable to obtain only potential differences with respect to a reference surface whose absolute potential is unknown. This situation suggests to modify the classical mixed boundary-value problem of physical geodesy by inserting into the boundary conditions an unknown additive constant, that must be determined by imposing a suitable additional constraint. Yet, such formulation of the boundary-value problem, from the point of view of its mathematical properties, is not unconditionally well-posed, and, furthermore, does not reflect faithfully the available physical model, as the present knowledge of ocean circulation does not allow to connect along coastlines the reference surfaces defined on the oceans and on the continents. The introduction of two different unknown additive constants, one for the oceans and one for the earth, to be determined by imposing two additional constraints, gives rise to a more faithful picture of the present physical knowledge, and, at the same time, to a new well-posed formulation of the boundary-value problem. This revised version was published online in August 2006 with corrections to the Cover Date.     

V-22后继者:四倾转旋翼机

在美国陆军"联合重型旋翼机"(JHL)项目的资助下,贝尔/波音直升机公司目前正在开展一种被称为四倾转旋翼机(QTR)的未来重型垂直起降运输机的研制工作。四倾转旋翼机的运载能力强于现在的 C-130运输机,并具有短距垂直起降能力,如果研制成功,将大大增强美军的战术运输能力。     

Origin of the Solar Wind: Theory

A theory is presented for the origin of the solar wind, which is based on the behavior of the magnetic field of the Sun. The magnetic field of the Sun can be considered as having two distinct components: Open magnetic flux in which the field lines remain attached to the Sun and are dragged outward into the heliosphere with the solar wind. Closed magnetic flux in which the field remains entirely attached to the Sun, and forms loops and active regions in the solar corona. It is argued that the total open flux should tend to be constant in time, since it can be destroyed only if open flux of opposite polarity reconnect, a process that may be unlikely since the open flux is ordered into large-scale regions of uniform polarity. The behavior of open flux is thus governed by its motion on the solar surface. The motion may be due primarily to a diffusive process that results from open field lines reconnecting with randomly oriented closed loops, and also due to the usual convective motions on the solar surface such as differential rotation. The diffusion process needs to be described by a diffusion equation appropriate for transport by an external medium, which is different from the usual diffusion coefficient used in energetic particle transport. The loops required for the diffusion have been identified in recent observations of the Sun, and have properties, both in size and composition, consistent with their use in the model. The diffusive process, in which reconnection occurs between open field lines and loops, is responsible for the input of mass and energy into the solar wind. This revised version was published online in August 2006 with corrections to the Cover Date.     

SPRI: simulator of polarimetric radar images

Simulator of polarimetric radar images (SPRI) consists of a suite of image processing programs for producing realistic millimeter-wave (MMW) radar images artificially on a workstation. The heart of the simulation approach is a polarimetric Rayleigh clutter simulator coupled to a clutter database. The simulator produces high resolution single-look polarimetric images. Hard targets can then be embedded into this clutter map, and the resultant image can be degraded in resolution, number of looks, polarization, etc. to match that which would be observed by a real sensor. Examples of simulated images, and comparisons of these simulations to actual images, are presented. The MMW Clutter Database is the most comprehensive to-date database of over 3500 Mueller matrices for many kinds of terrestrial clutter measured at 35 and 95 GHz, many of which are at incidence angles close to grazing. The database can be accessed via a World Wide Web flexible interface that enables data to be combined in new and unique ways specified by the user, and displayed in either tabular or graphical format. The structure and access procedure to the database are described     

Observations of interplanetary shocks: Recent progress

Interplanetary shock observations since the prior Solar Terrestrial Physics Symposium in 1978 are reviewed. Since the interval coincides with the recent solar maximum, emphasis is placed on shocks associated with transient solar phenomena, including coronal transients and eruptive prominences as well as flares. A good correlation between shocks and Storm Sudden Commencements has persisted into the recent maximum. Shocks have been identified that are associated with disappearing filaments and coronal transients rather than with flares. Significant progress has been made in the indirect observation of shocks near the Sun as a result of radio wave measurements in interplanetary space and measurement of the scintillation and spectral broadening of spacecraft radio transmissions. Preliminary results regarding the thickness of interplanetary shocks have appeared. Several quasi-parallel shocks propagating more nearly along, rather than across, the magnetic field have been identified. The plasma drivers accompanying interplanetary shocks have received increased attention and distinctive features have been found in electron, ion and magnetic field data.     

还管理学以本来面目

现代管理学的科学性并非是管理学固有的特征，管理的实践性、伦理性和艺术性才是管理理论所固有的本质特征。管理学最早的学术形式是一种与伦理学相联系的艺术学。现代管理学的科学性特征是近代科学的发展与应用而促成的，其“科学性”有余而“艺术性”不足的现状，已不能满足复杂、多变的现代社会发展的需要。要使管理学健康地发展，就必须促成其科学性与艺术性的统一、真善美的统一，培育“爱”的管理:“爱”即“责任”。     

ETW: simulations of true flight behaviour

The capabilities of the European Transonic Windtunnel ETW to simulate flight conditions by testing at cryogenic temperatures are presented. The achieved flow quality and tunnel control form the basis for an excellent data repeatability and a high confidence level in the deliverables. Unique instrumentation has been developed to provide additional information about the test object and the surrounding flow field during tunnel entries. Typical samples of Reynolds number effects are shown. Productivity aspects are considered on the basis of recently performed test scenarios.     

Modelling of grinding mechanics: A review

Grinding is one of the most widely used material removal methods at the end of many process chains. Grinding force is related to almost all grinding parameters, which has a great influence on material removal rate, dimensional and shape accuracy, surface and subsurface integrity, thermodynamics, dynamics, wheel durability, and machining system deformation. Considering that grinding force is related to almost all grinding parameters, grinding force can be used to detect grinding wheel wear, energy calculation, chatter suppression, force control and grinding process simulation. Accurate prediction of grinding forces is important for optimizing grinding parameters and the structure of grinding machines and fixtures. Although there are substantial research papers on grinding mechanics, a comprehensive review on the modeling of grinding mechanics is still absent from the literature. To fill this gap, this work reviews and introduces theoretical methods and applications of mechanics in grinding from the aspects of modeling principles, limitations and possible future trendencies.     

机上违规旅客问题:国际民航组织的新关注点

2011年5月2日至3日,新组建的"机上违规旅客专家组"在国际民航组织总部召开了第一次会议,机上违规旅客的法律问题再度引起关注。我国作为旅客运输量高居世界第二位的民航大国,此类事件也是日益凸显,亟需认真研究与分析。笔者将围绕该问题的形成、涉及的主要问题、我国的立法现状以及今后的发展趋势进行介绍与分析。