Enhancing mobile applications by combination of GNSS and W-CDMA

The location requirements for emergency callers outside urban areas can hardly be fulfilled without global navigation satellite systems (GNSS). Consequently, interest in positioning techniques based on use of a GNSS such as GPS or on the cellular network infrastructure itself is growing rapidly in the mobile-telephone community. Moreover, the increasing demand for commercial location-based services (LBS) has driven cellular-phone and network manufacturers to focus on positioning solutions which are even more accurate than the regulatory mandates for positioning of emergency callers. One example of these upcoming LBS is our PARAMOUNT project, which aims at improving user-friendly info-mobility services for hikers and mountaineers by combining wireless communications (GMTS), satellite navigation (GNSS) and geographic information systems (GIS), based on a mobile client/server architecture. The availability of mobile phones or PDAs with combined GNSS and cellular network-based wireless communication on a high integration level is one primary demand of such LBS applications. Based on this, we will give some initial answers to the question of whether mobile handset architecture synergies exist for the combination of GNSS with wireless location in CDMA cellular wireless networks. In order to identify synergies, we will outline similarities and differences between wireless communication and satellite navigation. In this respect, we pay particular attention to the so-called RAKE receiver architecture employed in mobile CDMA cellular handsets. Our initial investigations will show that the RAKE receiver architecture, on which mobile CDMA cellular handsets are based, will most likely be the one most suitable for achieving synergies between the two positioning techniques within the same mobile handset architecture. Consequently, several receiver components could be used to handle both types of signals (navigation and communications), resulting in a reduction of manufacturing costs and in a decrease in energy consumption. Electronic Publication     

Anatomically preserved plants in siderite concretions in the shale split of the Foord Seam: mineralogy, geochemistry, genesis (Upper Carboniferous, Canada)

A shale split in the well-studied Foord Seam (Upper Carboniferous), Stellarton Basin, Nova Scotia, provides a rare opportunity to study little known siderite concretions with anatomically preserved plants from a limnic basin. Siderite concretions occur throughout the split, commonly as sheet-like, inter-connected lepidodendrid logs, or less frequently as spherical masses; they are typically vuggy. A sample of 14 stratigraphically oriented concretions in the split shows that primary siderite varies from 45% to 80% (wt.%) due to selective replacement by 5% to 40% ferroan dolomite or ankerite in plant tissues. These two minerals show large Mg/Fe and Mg/Ca variability and are Fezoned. Clay content ranges from trace to 20%, and quartz from 5% to 10%. Partial cell-wall destruction by erosion and changeable oxic/anoxic conditions, prior to siderite permineralization, resulted in preservation mainly of the more resistant plant tissues. On average, carbon from siderite is isotopically heavier (+4.8±1.9 0/00) than that from ‘dolomite' (−7.2±1.1 0/00). The distribution of and the positive correlation between δ¹³C and δ¹⁸O probably reflects the two fractionation processes associated with methanogenesis and ‘dolomitization', respectively, in the genetic history of the siderite concretions in the split. Siderite concretions formed diagenetically early from bicarbonate under reducing conditions in a slightly alkaline freshwater environment that precluded calcite deposition.     

Mg---NH4 exchange on humic acid: A radiotracer technique for conditional exchange constants in a seawater medium

A radiotracer technique, employing ²⁷Mg, is used to determine the Mg released by ammonium exchange on undis-solved humic acid in a seawater medium. This new method allows for the measurement of exchangeable Mg on the solid phase surface, which eliminates the problem caused by the high-Mg background in the seawater matrix. The precision calculated from the counting statistics is better than ±2%; the reproducibility among repeated counts ranged from ±1% to ±3%. The higher sensitivity of the method allows for monitoring the Mg---NH₄ exchange at concentrations as low as 30 mM NH₄. This is a major improvement relative to the data obtained with the analytical methods used so far, which allow detection of exchangeable Mg only at NH₄ concentrations higher than 1 M. The lower experimental concentrations are more in accordance with the natural ammonium levels found in anoxic marine sediments. For the undissolved humic acid used in this experiment, the amount of exchangeable Mg in apparent equilibrium with an ammonium-free seawater matrix was found to be 96.6 ± 0.4 meq/100g. The Mg---NH₄ exchange on humic acid in seawater comes to a steady-state value in < 18 min. The conditional equilibrium constant obtained for this reaction, K_cond = 0.039 ± 0.001 M⁻¹. The technique can be expanded to other geochemical solid phases in seawater and it can be modified to study the behavior of the major cations by using ²⁴Na, ⁴²K and ⁴⁹Ca.     

Sulfurous acid (H2SO3) on Io?

Sulfurous acid (H₂SO₃) has never been characterized or isolated on Earth. This is caused by the unfavorable conditions for H₂SO₃ within Earth's atmosphere due to the high temperatures, the high water content and the oxidizing environment. Kinetic investigations by means of transition state theory showed that the half-life of H₂SO₃ at 300 K is 1 day but at 100 K it is increased to 2.7 billion years. Natural conditions to form H₂SO₃ presumably require cryogenic SO₂ or SO₂/H₂O mixtures and high energy proton irradiation at temperatures around 100 K. Such conditions can be found on the Jupiter moons Io and Europa. Therefore, we calculated IR-spectra of H₂SO₃ which we compared with Galileo's spectra of Io and Europa. From the available data we surmise that H₂SO₃ is present on Io and probably but to a smaller extent on Europa.     

Was a dacite dome implicated in the 9,500 <Emphasis Type="SmallCaps">b.p.</Emphasis> collapse of Mt Ruapehu? A palaeomagnetic investigation

Constraining the process by which volcanoes become unstable is difficult. Several models have been proposed to explain the driving forces which cause volcanic edifices to catastrophically collapse. These include models for destabilisation of volcanic flanks by wedging due to dyke intrusion and the weakening of mechanical properties by pressurisation of pore fluids. It is not known which, if any, of the models are relevant to particular sector collapse events. Recent developments in the palaeomagnetic estimation of emplacement temperatures of volcaniclastic rocks have shown that even relatively low emplacement temperatures can be recorded by volcaniclastics with high fidelity. We have carried out a palaeomagnetic study of emplacement temperatures to investigate the role of igneous activity in the initiation of the 9,500 b.p. Murimotu sector collapse of Mt Ruapehu, New Zealand. This debris avalanche deposit has three fades which are stratigraphically superimposed, and the lowermost fades contains three lithological assemblages representing different segments of the edifice which were transported with little internal mixing within the flow. We have determined that some of the dacite-bearing assemblage 1, fades 1 was hot (∼350 °C) during transport and emplacement, whereas none of the other lithological assemblages of fades contained hot material. Our interpretation is that a dacite dome was active on the ancient Ruapehu edifice immediately prior to the Murimotu sector collapse. The partially cooled carapace of the dome and material shed from this part was incorporated into the avalanche deposit, along with cold lavas and volcaniclastics. We have not found evidence for incorporation of material at or close to magmatic temperatures, at least in the sampled locations. Our palaeomagnetic work allows us to develop a comprehensive, new palaeomagnetic classification of volcaniclastics. Published online: 25 January 2003 Editorial responsibility: D. Dingwell     

Fidelity and time resolution of the magnetostratigraphic record in Siwalik sediments: high-resolution study of a complete polarity transition and evidence for cryptochrons in a Miocene fluviatile section

The Surai Khola section in southwest Nepal, a 5000 m continuously exposed record of fluvial sedimentation since Middle Miocene, was revisited for high-resolution magnetostratigraphy in sequences with expected cryptochrons and reversals of the geomagnetic field. Polarity intervals with durations of a few tens of thousands of years are recorded as zones of stable palaeomagnetic directions. Polarity transitions are recorded as zones with complex demagnetization behaviour of specimens in the sedimentary column. Almost antiparallel palaeoremanence directions, residing in different haematite phases in the same specimens, could generally not be separated properly by thermal demagnetization. Differing demagnetization paths for neighbouring specimens during a reversal suggest that measured transitional directions are not true geomagnetic field directions, but rather are generated by the superposition of variable amounts of at least two almost antiparallel components of magnetization. Accompanying studies of recent river sand deposits demonstrate that these sediments acquire a true depositional remanent magnetization (DRM) with considerable inclination errors and scattered directions for individual specimens.     

Propagation of MHD body and surface waves in magnetically structured regions of the solar atmosphere

The fact that magnetically structured regions exist in the solar atmosphere has been known for a number of years. It has been suggested that different kinds of magnetohydrodynamic (MHD) waves can be efficiently damped in these regions and that the dissipated wave energy may be responsible for the observed enhancement in radiative losses. From a theoretical point of view, an important task would be to investigate the propagation and dissipation of MHD waves in these highly structured regions of the solar atmosphere. In this paper, we study the behavior of MHD body and surface waves in a medium with either a single or double (slab) magnetic interface by use of a nonlinear, two-dimensional, time-dependent, ideal MHD numerical model constructed on the basis of a Lagrangean grid and semi-implicit scheme. The processes of wave confinement and wave energy leakage are discussed in detail. It is shown that the obtained results depend strongly on the type of perturbations imposed on the interface or slab and on the plasma parameter, . The relevance of the obtained results to the heating problem of the upper parts of the solar atmosphere is also discussed.     

南海东北部海底沉积物波的形态、粒度特征及物源、成因分析

在南海东北部广泛发育沉积物波。通过高分辨率多波束数据、地震剖面以及重力柱状样,对沉积物波的形态特征、粒度特征、物源以及形成机制进行了分析。研究表明大致以台湾浅滩南海底峡谷为界,北侧为近北东向展布,南侧为近南北向展布。对其分布规律、地貌和形态特征及重力柱状样粒度分析表明这些沉积物波为浊流成因。沉积物波的发育与新生代晚期研究区的构造活动密切相关,自距今6.5 Ma以来台湾造山运动使台湾岛强烈抬升剥蚀,这些剥蚀物为研究区提供了大量的陆源物质,而在南海东北部陆坡区大量发育的峡谷-冲沟系统为陆缘物质向下陆坡的输送提供了良好的通道。研究区西侧的东沙隆起长期处于抬升剥蚀状态,这种抬升剥蚀也为研究区沉积物波的发育提供了部分物源。随着坡度的减缓,浊流沉积物开始堆积,在台湾浅滩南海底峡谷的北侧形成了展布方向与冲沟垂直的沉积物波,而在南侧由于台湾浅滩南海底峡谷发生转向,浊流从水道中漫溢出来,沉积物堆积下来,形成了与原先水道近于垂直的近南北向的沉积物波。     

Low‐cost monitoring of snow height and thermal properties with inexpensive temperature sensors

Small, self‐recording temperature sensors were installed at several heights along a metal rod at five locations in a case study catchment. For each sensor, the presence or absence of snow cover was determined on the basis of its insulating effect and the resulting reduction of the diurnal temperature oscillations. Sensor coverage was then converted into a time series of snow height for each location. Additionally, cold content was calculated. Snow height and cold content provide valuable information for spring flood prediction. Good agreement of estimated snow heights with reference measurements was achieved and increased discharge in the study catchment coincided with low cold content of the snow cover. The results of the proposed distributed assessment of snow cover and snow state show great potential for (i) flood warning, (ii) assimilation of snow state data and (iii) modelling snowmelt process. Copyright © 2010 John Wiley & Sons, Ltd.