Integrated micro-electro-mechanical sensor development for inertialapplications

Electronic sensing circuitry and micro-electro-mechanical sense elements can be integrated to produce inertial instruments for applications unheard of a few years ago. This paper describes the Sandia M³EMS fabrication process, inertial instruments that have been fabricated, and the results of initial characterization tests of micro-machined accelerometers     

The prospects for enhanced international polar-orbiting satellite cooperation

With robust polar satellite missions demonstrated and/or operational in the USA, Europe, Japan, China, Russia, India, and Brazil, and with other nations also likely to develop such capability, this paper examines the prospects for as well as the potential challenges to closer and perhaps more formal international polar satellite cooperation. In suggesting that now is the time to explore the development of a coordinated polar observing system, the present paper identifies potential contributors, assesses the relevance of existing space-based Earth observation international coordination mechanisms, and considers three potential models for a future system.     

A strategy to study regional hydrology and terrestrial ecosystem processes using satellite remote sensing, ground-based data and computer modeling

This paper describes a multidisciplinary research project which seeks to characterize the terrestrial water cycle and use this characterization to derive simulations of carbon dioxide and methane flux. The water cycle work links interpolated climate fields, macrohydrologic models and Scanning Multichannel Microwave Radiometer datasets. The aim of the analysis is to use output from calibrated water balance models to develop relationships with SMMR datasets. SMMR estimates of surface hydrology can then be evaluated. Both modeled and SMMR datasets will be tested as inputs to regional biogeochemical models. All determinations will be made under climatically-averaged conditions and for 1979–1985, the years for which SMMR data is available.     

Further studies of waves accompanying the solar wind pick-up of interstellar hydrogen

Data collected by the magnetometer onboard the Ulysses spacecraft are surveyed for the occurrence of waves generated during the pick-up of interstellar hydrogen. Thirty one wave events were found during a 640 day study period, between March 21, 1992 and December 20, 1993 (after the Ulysses encounter with Jupiter). It is found that observation of the waves does not depend on the magnitude of the background magnetic field, but is a strong function of the angle between the magnetic field and the solar wind flow direction, with small angles being favored.     

Moving Emitter Classification

One of the problems that plague emitter location systems is the presence of data from emitters that are in motion. If this motion is not detected, erroneous location estimates and filled data files result. An algorithm to classify an emitter as moving or stationary is presented along with extensive illustrations and results based upon simulated data.     

A satellite interference location system using differential timeand phase measurement techniques

The design and development of a system for inferring the position of terrestrial satellite uplink stations using existing domestic satellites with minimal disruption to normal satellite operation are described. Two methods are presented by which a quantity measured at a terrestrial receiving site is mapped into a curve of possible uplink locations on the Earth's surface. One method involves measuring differential time delays of a single uplink signal observed through two adjacent spacecraft. The other uses a short baseline interferometer composed of the two cross-polarized and spatially separated antenna feeds aboard an affected satellite. A unique location is obtained by using an appropriate combination of the two methods. A system for measurement of the required differential delays and phases and experimental work performed to demonstrate the feasibility of the location methods are described     

An Algorithm Providing All-Attitude Capability for Three-Gimballed Inertial Systems

This paper describes an algorithm which protects a three-gimballed inertial system against gimbal lock while preserving the inertial reference. One sample of the gimbal angles and gimbal angle rates for a torque-free dynamic vehicle provides the information needed to determine whether or not gimbal lock will occur at some later time. When gimbal lock is imminent, the inertial platform is commanded to a new "safe" orientation, and knowledge of the inertial reference is updated accordingly. By iterating this process gimbal lock protection is extended to a vehicle subjected to torques. The results of digital simulations using the Apollo Primary Guidance, Navigation and Control System as a model are presented for various dynamic situations.     

Correlation of macro and micro cardiovascular function during weightlessness and simulated weightlessness

The investigation of cardiovascular function necessarily involves a consideration of the exchange of substances at the capillary. If cardiovascular function is compromised or in any way altered during exposure to zero gravity in space, then it stands to reason that microvascular function is also modified. We have shown that an increase in cardiac output similar to that reported during simulated weightlessness is associated with a doubling of the number of post-capillary venules and a reduction in the number of arterioles by 35%. If the weightlessness of space travel produces similar changes in cardiopulmonary volume and cardiac output, a reasonable expectation is that astronauts will undergo venous neovascularization. We have developed an animal model in which to correlate microvascular and systemic cardiovascular function. The microcirculatory preparation consists of a lightweight, thermo-neutral chamber implanted around intact skeletal muscle on the back of a rat. Using this technique, the performed microvasculature of the cutaneous maximus muscle may be observed in the conscious, unanesthetized animal. Microcirculatory variables which may be obtained include venular and arteriolar numbers, lengths and diameters, single vessel flow velocities, vasomotion, capillary hematocrit anastomoses and orders of branching. Systemic hemodynamic monitoring of cardiac output by electromagnetic flowmetry, and arterial and venous pressures allows correlation of macro- and microcirculatory changes at the same time, in the same animal. Observed and calculated hemodynamic variables also include pulse pressure, heart rate, stroke volume, total peripheral resistance, aortic compliance, minute work, peak aortic flow velocity and systolic time interval. In this manner, an integrated assessment of total cardiovascular function may be obtained in the same animal without the complicating influence of anesthetics.     

Solar wind low-energy energetic ion enhancements: A tool to forecast large geomagnetic storms

Predicting the occurrence of large geomagnetic storms more than an hour in advance is an important, yet difficult task. Energetic ion data show enhancements in flux that herald the approach of interplanetary shocks, usually for many hours before the shock arrival. We present a technique for predicting large geomagnetic storms (Kp  7) following the arrival of interplanetary shocks at 1 AU, using low-energy energetic ions (47–65 keV) and solar wind data measured at the L1 libration point. It is based on a study of the relationship between energetic ion enhancements (EIEs) and large geomagnetic storms by Smith et al. [Smith, Z., Murtagh, W., Smithtro, C. Relationship between solar wind low-energy energetic ion enhancements and large geomagnetic storms. J. Geophys. Res. 109, A01110, 2004. doi:10.1029/ 2003JA010044] using data in the rise and maximum of solar cycle 23 (February 1998–December 2000). An excellent correlation was found between storms with Kp  7 and the peak flux of large energetic ion enhancements that almost always (93% of time in our time period) accompany the arrival of interplanetary shocks at L1. However, as there are many more large EIEs than large geomagnetic storms, other characteristics were investigated to help determine which EIEs are likely to be followed by large storms. An additional parameter, the magnitude of the post-shock total magnetic field at the L1 Lagrangian point, is introduced here. This improves the identification of the EIEs that are likely to be followed by large storms. A forecasting technique is developed and tested on the time period of the original study (the training data set). The lead times, defined as the times from the arrival of the shock to the start of the 3-h interval of maximum Kp, are also presented. They range from minutes to more than a day; the average for large storms is 7 h. These times do not include the extra warning time given when the EI flux cross the high thresholds ahead of the shock. Because the data-stream used in the original study is no longer available, we extended the original study (1998–2000) to 2001, in order to: (a) investigate EIEs in 2001; (b) present a validation of the technique on an independent data set; (c) compare the results based on the original (P1) energy channel to those of the replacement (P1′) and (d), determine new EIE thresholds for forecasting geomagnetic storms using P1′ data. The verification of this P1′ training data set is also presented, together with lead times.     

芬兰,通往2010年世博会之路

世博会中的芬兰:建筑、设计和创造力芬兰一直是世界博览会积极的参与者。从第一届1851年伦敦世博会开始就已开始崭露头角,虽然当时作为俄国的一部分(芬兰