Textural controls on induced polarization and permeability in granular media

The spatial resolution visualized with hydrological models and the conceptualized images of subsurface hydrological processes often exceed resolution of the data collected with classical instrumentation at the field scale. In recent years it was possible to increasingly diminish the inherent gap to information from point like field data through the application of hydrogeophysical methods at field-scale. With regards to all common geophysical exploration techniques, electric and electromagnetic methods have arguably to greatest sensitivity to hydrologically relevant parameters. Of particular interest in this context are induced polarisation (IP) measurements, which essentially constrain the capacity of a probed subsurface region to store an electrical charge. In the absence of metallic conductors the IP- response is largely driven by current conduction along the grain surfaces. This offers the perspective to link such measurements to the characteristics of the solid-fluid-interface and thus, at least in unconsolidated sediments, should allow for first-order estimates of the permeability structure.¦While the IP-effect is well explored through laboratory experiments and in part verified through field data for clay-rich environments, the applicability of IP-based characterizations to clay-poor aquifers is not clear. For example, polarization mechanisms like membrane polarization are not applicable in the rather wide pore-systems of clay free sands, and the direct transposition of Schwarz' theory relating polarization of spheres to the relaxation mechanism of polarized cells to complex natural sediments yields ambiguous results.¦In order to improve our understanding of the structural origins of IP-signals in such environments as well as their correlation with pertinent hydrological parameters, various laboratory measurements have been conducted. We consider saturated quartz samples with a grain size spectrum varying from fine sand to fine gravel, that is grain diameters between 0,09 and 5,6 mm, as well as corresponding pertinent mixtures which can be regarded as proxies for widespread alluvial deposits. The pore space characteristics are altered by changing (i) the grain size spectra, (ii) the degree of compaction, and (iii) the level of sorting. We then examined how these changes affect the SIP response, the hydraulic conductivity, and the specific surface area of the considered samples, while keeping any electrochemical variability during the measurements as small as possible. The results do not follow simple assumptions on relationships to single parameters such as grain size. It was found that the complexity of natural occurring media is not yet sufficiently represented when modelling IP. At the same time simple correlation to permeability was found to be strong and consistent. Hence, adaptations with the aim of better representing the geo-structure of natural porous media were applied to the simplified model space used in Schwarz' IP-effect-theory. The resulting semi- empiric relationship was found to more accurately predict the IP-effect and its relation to the parameters grain size and permeability. If combined with recent findings about the effect of pore fluid electrochemistry together with advanced complex resistivity tomography, these results will allow us to picture diverse aspects of the subsurface with relative certainty. Within the framework of single measurement campaigns, hydrologiste can than collect data with information about the geo-structure and geo-chemistry of the subsurface. However, additional research efforts will be necessary to further improve the understanding of the physical origins of IP-effect and minimize the potential for false interpretations.¦-¦Dans l'étude des processus et caractéristiques hydrologiques des subsurfaces, la résolution spatiale donnée par les modèles hydrologiques dépasse souvent la résolution des données du terrain récoltées avec des méthodes classiques d'hydrologie. Récemment il est possible de réduire de plus en plus cet divergence spatiale entre modèles numériques et données du terrain par l'utilisation de méthodes géophysiques, notamment celles géoélectriques. Parmi les méthodes électriques, la polarisation provoquée (PP) permet de représenter la capacité des roches poreuses et des sols à stocker une charge électrique. En l'absence des métaux dans le sous-sol, cet effet est largement influencé par des caractéristiques de surface des matériaux. En conséquence les mesures PP offrent une information des interfaces entre solides et fluides dans les matériaux poreux que nous pouvons lier à la perméabilité également dirigée par ces mêmes paramètres. L'effet de la polarisation provoquée à été étudié dans différentes études de laboratoire, ainsi que sur le terrain. A cause d'une faible capacité de polarisation des matériaux sableux, comparé aux argiles, leur caractérisation par l'effet-PP reste difficile a interpréter d'une manière cohérente pour les environnements hétérogènes.¦Pour améliorer les connaissances sur l'importance de la structure du sous-sol sableux envers l'effet PP et des paramètres hydrologiques, nous avons fait des mesures de laboratoire variées. En détail, nous avons considéré des échantillons sableux de quartz avec des distributions de taille de grain entre sables fins et graviers fins, en diamètre cela fait entre 0,09 et 5,6 mm. Les caractéristiques de l'espace poreux sont changées en modifiant (i) la distribution de taille des grains, (ii) le degré de compaction, et (iii) le niveau d'hétérogénéité dans la distribution de taille de grains. En suite nous étudions comment ces changements influencent l'effet-PP, la perméabilité et la surface spécifique des échantillons. Les paramètres électrochimiques sont gardés à un minimum pendant les mesures. Les résultats ne montrent pas de relation simple entre les paramètres pétro-physiques comme par exemples la taille des grains. La complexité des media naturels n'est pas encore suffisamment représenté par les modèles des processus PP. Néanmoins, la simple corrélation entre effet PP et perméabilité est fort et consistant. En conséquence la théorie de Schwarz sur l'effet-PP a été adapté de manière semi-empirique pour mieux pouvoir estimer la relation entre les résultats de l'effet-PP et les paramètres taille de graines et perméabilité. Nos résultats concernant l'influence de la texture des matériaux et celles de l'effet de l'électrochimie des fluides dans les pores, permettront de visualiser des divers aspects du sous-sol. Avec des telles mesures géo-électriques, les hydrologues peuvent collectionner des données contenant des informations sur la structure et la chimie des fluides des sous-sols. Néanmoins, plus de recherches sur les origines physiques de l'effet-PP sont nécessaires afin de minimiser le risque potentiel d'une mauvaise interprétation des données.

Soil diffuse degassing and thermal energy fluxes from the southern Lakki plain, Nisyros (Greece)

Two diffuse soil CO2 flux surveys from the southern Lakki plain show that CO2 is mainly released from the hydrothermal explosion craters. The correspondence between high CO2 fluxes and elevated soil temperatures suggests that a flux of hot hydrothermal fluids ascends towards the surface. Steam mostly condenses near the surface and the heat given off is conductively transferred to the atmosphere through the soil, accompanied by a large CO2 flux. Tt was calculated, that 68 t d(-1) of hydrothermal CO2 are released through the total surveyed area of similar to1.3 km(2) Admitting that a steam flux of 2200 t d(-1) accompanies this CO2 flux, the thermal energy released through steam condensation amounts to 58 MW.

In conspectu prope totius urbis: an application of different visual methods at the ager Tarraconensis landscape

We present in this paper the results of the application of several visual methods on a group of locations, dated between VI and I centuries BC, of the ager Tarraconensis (Tarragona, Spain) a Hinterland of the roman colony of Tarraco. The difficulty in interpreting the diverse results in a combined way has been resolved by means of the use of statistical methods, such as Principal Components Analysis (PCA) and K-means clustering analysis. These methods have allowed us to carry out site classifications in function of the landscape's visual structure that contains them and of the visual relationships that could be given among them.

Linear and nonlinear terrain deformation maps from a reduced set of interferometric SAR images

In this paper, an advanced technique for the generation of deformation maps using synthetic aperture radar (SAR) data is presented. The algorithm estimates the linear and nonlinear components of the displacement, the error of the digital elevation model (DEM) used to cancel the topographic terms, and the atmospheric artifacts from a reduced set of low spatial resolution interferograms. The pixel candidates are selected from those presenting a good coherence level in the whole set of interferograms and the resulting nonuniform mesh tessellated with the Delauney triangulation to establish connections among them. The linear component of movement and DEM error are estimated adjusting a linear model to the data only on the connections. Later on, this information, once unwrapped to retrieve the absolute values, is used to calculate the nonlinear component of movement and atmospheric artifacts with alternate filtering techniques in both the temporal and spatial domains. The method presents high flexibility with respect to the required number of images and the baselines length. However, better results are obtained with large datasets of short baseline interferograms. The technique has been tested with European Remote Sensing SAR data from an area of Catalonia (Spain) and validated with on-field precise leveling measurements.

A two-dimensional doppler-radiometer for earth observation

Compared to synthetic aperture radars (SARs), the angular resolution of microwave radiometers is quite poor. Traditionally, it has been limited by the physical size of the antenna. However, the angular resolution can be improved by means of aperture synthesis interferometric techniques. A narrow beam is synthesized during the image formation processing of the cross-correlations measured at zero-lag between pairs of signals collected by an array of antennas. The angular resolution is then determined by the maximum antenna spacing normalized to the wavelength (baseline). The next step in improving the angular resolution is the Doppler-Radiometer, somehow related to the super-synthesis radiometers and the Radiometer-SAR. This paper presents the concept of a three-antenna Doppler-Radiometer for 2D imaging. The performance of this instrument is evaluated in terms of angular/spatial resolution and radiometric sensitivity, and an L-band illustrative example is presented.

Polarimetric radar interferometry for improved mine detection and surface clutter rejection

A recently developed technique, polarimetric radar interferometry, is applied to tackle the problem of the detection of buried objects embedded in surface clutter. An experiment with a fully polarimetric radar in an anechoic chamber has been carried out using different frequency bands and baselines. The processed results show the ability of this technique to detect buried plastic mines and to measure their depth. This technique enables the detection of plastic mines even if their backscatter response is much lower than that of the surface clutter.

SAR Interferometric phase noise reduction using wavelet transform

The problem of synthetic aperture radar interferometric phase noise reduction is addressed. A new technique based on discrete wavelet transforms is presented. This technique guarantees high resolution phase estimation without using phase image segmentation. Areas containing only noise are hardly processed. Tests with synthetic and real interferograms are reported.

Enzymes musculaires et exercice physique [Muscle enzyme activity and exercise]

Exercise is classically associated with muscular soreness, presenting one to two days later, delayed onset muscular soreness. Blood muscle enzymes and protein elevations are characteristic, and may cause renal failure. Creatin phosphokinase peak appears on the fourth day and depends on exercise type and individual parameters. This effect is attenuated with repeated bouts, by habituation. Metabolic complications are rare. The knowledge of this reaction, even with common exercises, allows to postpone investigations for a complex metabolic disorder, or to avoid stopping a medication for fear of a side effect, as with statins. Indeed, it is necessary to wait for seven days without any exercise before interpreting an elevated CK result.

Tietoturvainformaation ja -tapahtumien hallinta PCI DSS -standardissa

Työn keskeisimpänä tavoitteena on tutkia SIEM-järjestelmien (Security Information and Event Management) käyttömahdollisuuksia PCI DSS -standardissa (Payment Card IndustryData Security Standard) lähtökohtaisesti ratkaisutoimittajan näkökulmasta. Työ on tehty Cygate Oy:ssä. SIEM on uusi tietoturvan ratkaisualue, jonka käyttöönottoa vauhdittavat erilaiset viralliset sääntelyt kuten luottokorttiyhtiöiden asettama PCI DSS -standardi. SIEM-järjestelmien avulla organisaatiot pystyvät keräämään valmistajariippumattomasti verkon systeemikomponenteista tapahtumatietoja, joiden avulla pystytään näkemään keskitetysti, mitä verkossa on tapahtunut. SIEM:ssa käsitellään sekä historiapohjaisia että reaaliaikaisia tapahtumia ja se toimii organisaatioiden keskitettynä tietoturvaprosessia tukevana hallintatyökaluna. PCI DSS -standardi on hyvin yksityiskohtainen ja sen vaatimusten täyttäminen ei ole yksinkertaista. Vaatimuksenmukaisuutta ei saavuteta hetkessä, vaan siihen liittyvä projekti voi kestää viikoista kuukausiin. Standardin yksi haasteellisimmista asioista on keskitetty lokien hallinta. Maksukorttitietoja käsittelevien ja välittävien organisaatioiden on kerättävä kaikki audit-lokit eri järjestelmistä, jotta maksukorttitietojen käyttöä pystytään luottamuksellisesti seuraamaan. Standardin mukaan organisaatioiden tulee käyttää myös tunkeutumisen ja haavoittuvuuksien havainnointijärjestelmiä mahdollisten tietomurtojen havaitsemiseksi ja estämiseksi. SIEM-järjestelmän avulla saadaan täytettyä PCI DSS -standardin vaativimpia lokien hallintaan liittyviä vaatimuksia ja se tuo samallamonia yksityiskohtaisia parannuksia tukemaan muita standardin vaatimuskohtia. Siitä voi olla hyötyä mm. tunkeutumisen ja haavoittuvuuksien havainnoinnissa. SIEM-järjestelmän hyödyntäminen standardin apuna on kuitenkin erittäin haasteellista. Käyttöönotto vaatii tarkkaa etukäteissuunnittelua ja kokonaisuuksien ymmärtämistä niin ratkaisutoimittajan kuin ratkaisun käyttöönottajan puolelta.

Nappe geometry in the Western Swiss Alps

Detailed geological mapping during the last 20 years in the Western Swiss Alps has shown clearly that most of the lower basement nappes are fold nappes possessing normal and inverted limbs. Moreover their cores are made of strongly deformed gneisses indicating that important ductile strain took place during the formation of the fold nappes. It is therefore probably wrong to imagine deep basement nappes as rigid slices as often actually claimed, especially when interpreting seismic profiles. True `brittle type' thrust nappes involving basement rocks only occur in the internal and upper parts of the belt. Cover nappes, on the contrary, are in most parts of the Alpine belt thrust sheets following more or less the rules of thin-skinned tectonics. Many basement fold nappes lost part of their sedimentary cover during or just before their formation, by decollement along ductile horizons. The result is that many cover thrust nappes in the external part of the Alps are directly related to their original basement fold nappes.

European climate variations over the past half-millennium reconstructed from groundwater

Temperature reconstructions for recent centuries are the basis of estimations of the natural variability in the climate system before and during the onset of anthropogenic perturbation. Here we present, for the first time, an independent and physically based reconstruction of mean annual temperature over the past half millennium obtained from groundwater in France. The reconstructed noble gas temperature (NGT) record suggests cooler than present climate conditions throughout the 16th-19th centuries. Periods of warming occur in the 17th-18th and 20th century, while cooling is reconstructed in the 19th century. A noticeable coincidence with other temperature records is demonstrated. Deuterium excess varies in parallel with the NGT, and indicates variation in the seasonality of the aquifer recharge; whereas high excess air in groundwater indicates periods with high oscillations of the water table.

Tukkilajittelun röntgenmittauksen hyödyntäminen, tapaus Korkeakosken saha

Diplomityön tavoitteena oli selvittää työn toimeksiantajan UPM, Korkeakosken sahan röntgenmittauslaitteen oksaindeksilajitteluparametrille lukuarvo, jolla päästään A-tukkien osalta tavoiteltuun sydänsahatavaralaatujakaumaan eli saadaan siirrettyä VI- sydänsahatavaralaatu B-tukkien joukkoon. Lisäksi työssä tutkittiin sahan tukkilajittelun röntgenmittauslaitteen mittauksen toimivuutta ja sen tehokkaampaa hyödyntämistä. Korkeakosken sahan käyttämä röntgenmittauslaite on Bintec Oy:n kehittämä ja on tyypiltään Wood-X-4D. Laitteen mittaus perustuu tukin kuvaamiseen viipaleinaeli tomografiamittaukseen. Laite mittaa tukista useita ominaisuuksia ja antaa niiden perusteella lajitteluparametreille lukuarvoja. Lajitteluparametriarvojen muuttaminen vaikuttaa syntyvään sydänsahatavaralaatujakaumaan. Työ suoritettiin röntgenmittauslaitteella tekemällä tukeille toistomittauksia ja lajittelukokeita. Kokeissa käytettävät tukit olivat halkaisijaltaan 230 mm - tukkiluokasta. Tukkeja lajiteltiin eri tukkilaatulajitteluasetuksilla, jolloin seurattiin niistä sahattavia sahatavaralaatuja. Sahatavaralaatujen määrityksessä käytettiin sahaosastolla olevaa Finscan Oy:n kehittämää BoardMaster-NT-lajittelumittalaitetta. Tutkimus osoitti, että oksaindeksin pudottamisella, ei päästy työnantajan asettamaan sydänsahatavaran laatulajittelutavoitteeseen sallituissa oksaindeksirajoissa. Tavoitteen saavuttaminen olisi edellyttänyt oksaindeksin arvon pudottamista selkeästi alle asetetun 28 rajan. Tutkimustulokset osoittivat, että röntgenmittalaitteen lajitteluparametrien toiminnan varmuus vaihteli merkittävästi riippuen käytettävästä parametrista ja että laitteen mittaustarkkuus kärsi laitteen yleiseksi viaksi todetun detektorivian myötä. Täten tarkka laatulajittelu edellyttää röntgenmittalaitteen kaikkia neljää toimivaa detektoria. Tämä pystytään varmistamaanvaradetektorilla.

Asunto-osakkeiden kauppa korjausrakentamisen näkökulmasta

Tutkielman pääaiheena on asunto-osakkeiden kauppa. Keskeisimpänä tutkimusaiheena on myyjän asemesta korjausrakentamiseen painottuva näkökulma. Tutkielman tarkoituksena on analysoida omistuksen, statuksen ja päätöksenteon vaikutusta myyjän vastuisiin. Tutkielmassa pyritään myös selvittämään asunto-osakeyhtiön omistuspohjan merkitystä elinkeinonharjoittajana toimivan osakkaan vastuisiin. Metodina käytetään vertailevaa tutkimusotetta, painottuenosaltaan kausaliteettiin. Teemaa koskevan analyysin avulla pyritään lainsäädännön sisältä tulkitsemaan ja selkeyttämään asuntokauppaan liittyviä ongelmia. Praktisen lähestymistavan avulla pyritään tuottamaan viitekehys, joka palvelee voimassaolevan normatiivisen tiedon kehittämistä. Tutkielma osoittaa, että lainsäädäntö on jakautunut asunto-osakkeiden kaupan näkökulmasta tavalla, jota voidaan kritisoida. Asuntokauppalaissa sääntely ei kohdistu tilanteisiin, joissa huomioitaisiin korjausrakentamisen moniulotteisuus. Pikemminkin käytännön näkökulmasta on nähtävissä suunta, jossa korostetaan tiedon merkitystä osanavaihdantaa jopa sisällön ja validiteetin kustannuksella

Evolution and sedimentology of a channel fill in the sandy braided South Saskatchewan River and its comparison to the deposits of an adjacent compound bar

The depositional stratigraphy of within-channel deposits in sandy braided rivers is dominated by a variety of barforms (both singular `unit' bars and complex `compound' bars), as well as the infill of individual channels (herein termed `channel fills'). The deposits of bars and channel fills define the key components of facies models for braided rivers and their within-channel heterogeneity, knowledge of which is important for reservoir characterization. However, few studies have sought to address the question of whether the deposits of bars and channel fills can be readily differentiated from each other. This paper presents the first quantitative study to achieve this aim, using aerial images of an evolving modern sandy braided river and geophysical imaging of its subsurface deposits. Aerial photographs taken between 2000 and 2004 document the abandonment and fill of a 1 3 km long, 80 m wide anabranch channel in the sandy braided South Saskatchewan River, Canada. Upstream river regulation traps the majority of very fine sediment and there is little clay (<1%) in the bed sediments. Channel abandonment was initiated by a series of unit bars that stalled and progressively blocked the anabranch entrance, together with dune deposition and stacking at the anabranch entrance and exit. Complete channel abandonment and subsequent fill of up to 3 m of sediment took approximately two years. Thirteen kilometres of ground-penetrating radar surveys, coupled with 18 cores, were obtained over the channel fill and an adjacent 750 m long, 400 m wide, compound bar, enabling a quantitative analysis of the channel and bar deposits. Results show that, in terms of grain-size trends, facies proportions and scale of deposits, there are only subtle differences between the channel fill and bar deposits which, therefore, renders them indistinguishable. Thus, it may be inappropriate to assign different geometric and sedimentological attributes to channel fill and bar facies in object-based models of sandy braided river alluvial architecture.