Low Energy Transfer to the Moon

In 1991, the Japanese Hiten mission used a low energy transfer with a ballistic capture at the Moon which required less Vthan a standard Hohmann transfer. In this paper, we apply the dynamical systems techniques developed in our earlier work to reproduce systematically a Hiten-like mission. We approximate the Sun–Earth–Moon-spacecraft 4-body system as two 3-body systems. Using the invariant manifold structures of the Lagrange points of the 3-body systems, we are able to construct low energy transfer trajectories from the Earth which execute ballistic capture at the Moon. The techniques used in the design and construction of this trajectory may be applied in many situations.     

The geography of the elderly in a modernizing society: the Hong Kong case

The characteristics of the elderly population of Hong Kong are first described. Recent changes in the spatial distribution of the elderly are also detailed. The spatial distribution and internal migration patterns of the elderly are shown to be very similar to those of the population as a whole. The problems posed by the fact that many of the elderly are poorly educated and lowly paid are considered.     

The measurement of soil gases and shallow temperature for determination of active faults in a geothermal area: a case study from Ömer–Gecek,Afyonkarahisar (West Anatolia)

Afyonkarahisar is a very important geothermal province of western Anatolia and has low and medium enthalpy geothermal areas. This study has been carried out for the preparation of distribution maps of soil gases (radon and carbon dioxide) and shallow soil temperature and the exploration of permeable tectonic regions associated with geothermal systems and reveal the origins of radon and carbon dioxide gases. The western district of the study area is characterized by the high radon concentration (168.30 kBq/m³), carbon dioxide ratio (0.30%), and soil temperature (21.0 °C) values. Fethibey and Demirçevre faults, which allow the circulation of geothermal fluids, have been detected in the distribution maps of radon, carbon dioxide, and shallow depth temperature and the directions of the curves in these maps correspond to the strikes of Demirçevre faults. The effect of the fault plays an important role in the change of carbon dioxide concentration along the W-E directional geological section prepared to determine the change of soil gas and shallow depth temperature values depending on lithological differences, fault existence, and geothermal reservoir depth. On the other hand, it was determined that Rn²²² concentration and soil temperature changed as a function of geothermal reservoir depth or lithological difference. Tuffs in Köprülü volcano-sedimentary units are the main source of radon due to their higher uranium contents. Besides, the carbon dioxide in Ömer–Gecek soils has geothermal origin because of the highest carbon dioxide content (99.3%) in non-condense gas. The similarities in patterns of soil temperature, radon, and carbon dioxide indicate that the variation in soil temperatures is related to radon and carbon dioxide emissions. It is concluded that soil gas and temperature measurements can be used to determine the active faults in the initial stage of geothermal exploration successfully.     

A site evaluation campaign for a ground based atmospheric Cherenkov telescope in Romania

Around the world, several scientific projects share the interest of a global network of small Cherenkov telescopes for monitoring observations of the brightest blazars??the DWARF network. A small, ground based, imaging atmospheric Cherenkov telescope of last generation is intended to be installed and operated in Romania as a component of the DWARF network. To prepare the construction of the observatory, two support projects have been initiated. Within the framework of these projects, we have assessed a number of possible sites where to settle the observatory. In this paper we submit a brief report on the general characteristics of the best four sites selected after the local infrastructure, the nearby facilities and the social impact criteria have been applied.     

40Ar/39Ar dating of the Jiali and Gaoligong shear zones: Implications for crustal deformation around the Eastern Himalayan Syntaxis

We conducted a comprehensive ⁴⁰Ar/³⁹Ar geochronological study of the Jiali and Gaoligong shear zones to obtain a better understanding of crustal deformation and tectonic evolution around the Eastern Himalayan Syntaxis (EHS). The new age data reveal that the main phase of deformation in the Jiali and Gaoligong shear zones occurred from 22 to 11 Ma and from 18 to 13 Ma, respectively. Structural data collected during this study indicate that the Jiali shear zone underwent a change in shear sense from sinistral to dextral during its movement history. Based on a comparison with the deformation histories of other major shear zones in the region, we argue that the initial sinistral motion recorded by the Jiali shear zone was coincident with that of the Ailao Shan–Red River shear zone, which marked the northern boundary of the southeastward extrusion of the Indochina block during the Early Miocene. From the Middle Miocene (～18 Ma), the Jiali shear zone changed to dextral displacement, becoming linked with the dextral Gaoligong shear zone that developed as a consequence of continued northward indentation of the Indian continent into Asia. Since this time, the Jiali and Gaoligong shear zones have been united, defining the southwestern boundary of the EHS during clockwise rotation of the eastward-extruding Tibetan block, as revealed by recent GPS data. The temporal change in regional deformation pattern from southeastward block extrusion to clockwise rotation of crustal fragments may have played an important role in the development of the eastern Himalayan drainage system around the EHS.     

Die Entstehung einiger tektonischer Grundbegriffe. Ein Beitrag zur Geschichte der Geologie

Zusammenfassung Die ersten tektonischen Vorstellungen legte 1669Nic. Steno in seinem Prodromus nieder. Seine Beobachtungen an horizontalen und geneigten Schichten führten später zu dem Begriffe der orogenetischen Diskordanzen. L.Élie de Beaumont ist sein direkter Nachfolger geworden, während J.Hutton ganz unabhängig von beiden den Diskordanzbegriff entwickelte. Die neptunistische Lehre von A. G.Werner ging von einem primären, von Wasserfluten geschaffenen Relief der Erdoberfläche aus, das überschichtet wurde. Doch auchWerner dachte daneben ebenfalls an große Höhlen, deren Decken einbrechen würden. Die neptunistischen Schwierigkeiten ergaben sich aus der Unmöglichkeit einer vertikalen Sedimentation von primär senkrecht gestellten Schichten. Die Anfänge der Erforschung der Tektonik des Rheingrabens werden dargelegt, und es wird besonders gezeigt, daßÉlie de Beaumont, der 1836 von einem eingebrochenen Gewölbe sprach, schon vorher Kenntnis eines eingebrochenen Gewölbes von Island und eines Schichtgewölbes von Württemberg über Schwarz wald — Vogesen nach Lothringen hatte. Die Zeit des Einbruches legteÉ. de Beaumont irrtümlich in die Zeit des Buntsandsteins.Theorien der Gebirgsbildung wurden mit L. v.Buch's Erhebungstheorie und geognostischen Gebirgssystemen um zwei weitere Ideen 1824–1835 erweitert.Élie de Beaumont baute diese Theorie sehr aus und sprach von Revolutionen der Erdkruste (1829). Die Faltengebirge fanden in J.Thurmann (1832) ihren ersten gründlichen Bearbeiter, der am Beispiel des Faltenjuras nachwies, daß doch nur Horizontalkräfte am Werke gewesen sein können und die Erhebungstheorie L. v.Buch's für diese Gebirgsarten keine Erklärung bringe. Zum Schlusse wird die Geschichte des Geologenkompasses gebracht.

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Nic. Steno was the first who developed tectonic ideas in his Prodromus in 1669. His observations in the surroundings of Firenze (Italy) led him to the notion what nowadays is called a discordance by orogeny. He was followed by the French L.Élie de Beaumont, while the Scotchman J.Hutton developed this term of tectonic discordance quite independently of both.The neptunic theory of A. G.Werner in Freiberg (Saxony) started from the idea that the primary relief of the surface of the earth was formed by floods and covered with sediments. Furtheron he assumed large caves, the tops of them having broken down, explaining in this manner very inclined strata. The difficulties in this neptunic theory resulted from the fact that it was impossible to account for a sedimentation in a vertical line as seen in vertical layers.The author gives a survey of the first researches in the tectonics of the Rhinegraben and shows thatÉlie de Beaumont, who in 1836 mentioned the breakdown of the central ridge of a vault, so forming the rift-valley, had already some information of such a pressure arch in Iceland and of a second one stretching from Würtemberg via Black Forest—Vosges to Lorraine.Élie de Beaumont misdated the collapse of this large vault, stating erroneously the time of Buntsandstein (=New Red Sandstone).Between 1824 and 1835 L. v.Buch developed two further theories on orogenesis, that of the elevation-crater hypothesis and that of the geognostic systems of mountains. É.de Beaumont completedBuch's theory and in 1829 he spoke of revolutions of the earth's crust.The first who thoroughly researched the Swiss Jura was J.Thurmann. Quoting the folded strata of this region as an example he proved that only horizontal stresses could have been responsible for the formation of these mountains and that the elevation-crater hypothesis of L. v.Buch acting only with vertical forces could not give any explanation for it.Finally the author recapitulates the history of the geologist's compass.

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Résumé Les premières conceptions tectoniques ont été exposées en 1669 par N.Steno dans son « Prodrome ». Ses observations sur des strates horizontales ou inclinées ont conduit ultérieurement à la notion de discordances orogéniques. L.Élie de Beaumont fut son successeur direct, cependant que J.Hutton, tout à fait indépendamment des deux premiers développa la notion de discordance. La théorie neptuniste de A. G.Werner se basait sur l'existence préalable d'un relief terrestre créé par les flots et qui aurait été noyé sous les strates des dépôts ultérieurs. Pourtant, dans un autre ordre d'idées,Werner pensait aussi à l'existence d'immenses grottes dont les toits s'effondreraient. Les neptunistes éprouvèrent des difficultés résultant de l'impossibilité d'expliquer des couches redressées par une sédimentation verticale. L'auteur expose les débuts des recherches sur la tectonique du fossé rhénan et montre en particulier qu'Élie de Beaumont, qui parla en 1836 d'une voûte effondrée avait déjà auparavant eu connaissance d'une voûte effondrée en Islande et d'une voûter structurale allant du Wurttemberg en Lorraine par-dessus la Forêt-Noire et les Vosges. Par erreur,É de Beaumont plaça le moment de cet effondrement à l'époque du grès bigarré.Avec la théorie des soulèvements et des orogènes géognostiques L. v.Buch enrichit de 1824–1835 les théories orogéniques de deux concepts supplémentaires.Élie de Beaumont les développa et parla de révolution de la croûte terrestre (1829). Les premières recherches approfondies sur les chaînes plissées sont dues à J.Thurmann (1832) qui, d'après l'exemple du Jura plissé, démontra que seules des forces horizontales ont pu avoir été à l'oeuvre et que la théorie des soulèvements de L.von Buch n'apportait pas d'explication pour les chaînes de ce type.Pour terminer, l'auteur expose l'histoire de la boussole du géologue.

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The use of 3D modeling for the prediction of the seismic demands on the gravity dams

Seismic behavior of gravity dams has long been evaluated using a representative two‐dimensional (2D) system. Formulated for the gravity dams built in wide canyons, the assumption is nevertheless utilized extensively for almost all concrete dams due to the established procedures as well as the expected computational costs of a three‐dimensional model. However, a significant number of roller‐compacted concrete dams, characterized as such systems, do not conform to the basic assumptions of these methods by violating the conditions on canyon dimensions and joint‐spacing/details. Based on the premise that the 2D modeling assumption is overstretched for practical purposes in a variety of settings, the purpose of this study is to critically evaluate the use of 2D modeling for the prediction of the seismic demands on these systems. Using a rigorous soil–structure interaction approach, the difference between the two and three‐dimensional response for gravity dams was investigated first in the frequency domain for a range of canyon widths and foundation to dam moduli ratios. Then, the time domain differences between the crest displacements and the maximum principal stress were obtained using 70 different ground motions in order to show the possible bias introduced into the analysis results due to the modeling approach. The results of the study show that even for relatively wide canyons, the 2D analysis can lead to misleading predictions. Copyright © 2017 John Wiley & Sons, Ltd.