Shaking table tests of a full-scale flat-bottom manufactured steel silo filled with wheat: Main results on the fixed-base configuration     

Stefano Silvestri  Sulyman Mansour  Matteo Marra  Johann Distl  Marco Furinghetti  Igor Lanese  Enrique Hernndez-Montes  Caterina Neri  Michele Palermo  Alberto Pavese  Elisa Rizzo Parisi  Adam Jan Sadowski  Francesco Selva  Tomoyo Taniguchi  Laura Vadrucci  Felix Weber 《地震工程与结构动力学》2022,51(1):169-190

This paper reports on a series of shaking table tests on a full-scale flat-bottom steel silo filled with soft wheat, characterized by aspect ratio of around 0.9. The specimen was a 3.64-m diameter and 5.50-m high corrugated-wall cylindrical silo. Multiple sensors were used to monitor the static and dynamic response of the filled silo system, including accelerometers and pressure cells. Numerous unidirectional dynamic tests were performed consisting of random signals, sinusoidal inputs, and both artificial and real earthquake records. The objectives of this paper are (i) to provide a general overview of the whole experimental campaign and (ii) to present selected results obtained for the fixed-base configuration. The measured data were processed to assess the static pressures, the dynamic overpressures (related to the effective mass) and the accelerations of monitored points on the silo wall, and to identify the basic dynamic properties (fundamental frequency of vibration, damping ratio, dynamic amplification factors) of the filled silo. The main findings are discussed and compared with the predictions given by available theoretical models and code provisions. It is found that the fundamental frequency slightly decreases with increasing acceleration, while it slightly increases with increasing compaction of the granular material. For close-to-resonance input, the dynamic amplification (in terms of peak values of accelerations) increases along the height of the silo wall up to values of around 1.4 at the top surface of the solid content. The dynamic overpressures appear to increase with depth (differently from the EN1998-4 expectations), and to be proportional to the acceleration.  相似文献   

Water in the Earth’s Lower Mantle     

Felix V. Kaminsky 《Geochemistry International》2018,56(12):1117-1134

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Towards sustainable urban development: the social acceptability of high-rise buildings in a Ghanaian city     

Felix S. K. Agyemang  Elisabete Silva  Prince Aboagye Anokye 《GeoJournal》2018,83(6):1317-1329

Over the years, many city managers, policy makers and academics alike have turned to high-rise buildings as pathway to sustainable urban development. However, the sustainability of such types of development in various geographical contexts, especially in sub-Saharan Africa, is a subject less explored. Amidst the promotion of high-rise development in a rapidly urbanizing metropolis in Ghana, Kumasi, the research empirically examined the social acceptability of high-rise residential facilities and the institutional capacity for their effective management. By conducting face-to-face interviews with sampled households, and critical public service providers in the metropolis, the study uncovered that, contrary to the evidence from many Asian cities, there is generally low social acceptability of high-rise developments, and a weak institutional capacity for effective service delivery. The research concludes that, whilst it is tempting to embrace high-rise buildings as sustainable development pathway, it is crucial they are pursued with much circumspection. In addition to their design being tailored to the local needs of the people for whom they are built, the promotion of high-rise development should recognize the importance of effective service delivery, and general social acceptability.  相似文献   

Kimberlites distribution in Angola and prospective areas for new discoveries     

Ustinov  Victor N.  Feijo Bartolomeu  Ana M.  Zagainy  Alexander K.  Felix  Joao T.  Mikoev  Igor I.  Stegnitskiy  Yury B.  Lobkova  Ludmila P.  Kukui  Irina M.  Nikolaeva  Evelina V.  Antonov  Sergei A. 《Mineralogy and Petrology》2018,112(2):383-396

Based on a comprehensive analysis of kimberlite pipes of Angola, including the near surface structural setting, deep lithospheric structure, pipe morphology and emplacement, mineralogical and petrographic features, diamond characteristics and locations of secondary deposits four geographical regions have been outlined within Angola representing four types of diamond bearing potential. These areas include high diamond bearing potential pipes, possible potential, no potential, and unclear potential areas. It was found that the depth of magmatism and diamond potential of kimberlites increases from the Atlantic coast in southwestern Angola into the continent in the north-easterly direction. Areas prospective for the discovery of new primary diamond deposits have been identified.

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Integer ambiguity resolution in precise point positioning: method comparison   总被引：24，自引：10，他引：14  

Jianghui Geng  Xiaolin Meng  Alan H. Dodson  Felix N. Teferle 《Journal of Geodesy》2010,84(9):569-581

Integer ambiguity resolution at a single receiver can be implemented by applying improved satellite products where the fractional-cycle biases (FCBs) have been separated from the integer ambiguities in a network solution. One method to achieve these products is to estimate the FCBs by averaging the fractional parts of the float ambiguity estimates, and the other is to estimate the integer-recovery clocks by fixing the undifferenced ambiguities to integers in advance. In this paper, we theoretically prove the equivalence of the ambiguity-fixed position estimates derived from these two methods by assuming that the FCBs are hardware-dependent and only they are assimilated into the clocks and ambiguities. To verify this equivalence, we implement both methods in the Position and Navigation Data Analyst software to process 1 year of GPS data from a global network of about 350 stations. The mean biases between all daily position estimates derived from these two methods are only 0.2, 0.1 and 0.0 mm, whereas the standard deviations of all position differences are only 1.3, 0.8 and 2.0 mm for the East, North and Up components, respectively. Moreover, the differences of the position repeatabilities are below 0.2 mm on average for all three components. The RMS of the position estimates minus those from the International GNSS Service weekly solutions for the former method differs by below 0.1 mm on average for each component from that for the latter method. Therefore, considering the recognized millimeter-level precision of current GPS-derived daily positions, these statistics empirically demonstrate the theoretical equivalence of the ambiguity-fixed position estimates derived from these two methods. In practice, we note that the former method is compatible with current official clock-generation methods, whereas the latter method is not, but can potentially lead to slightly better positioning quality.  相似文献   

In the Shadows of the Tropics: Climate, Race and Biopower in Nineteenth Century Ceylon – By James S. Duncan     

Felix Driver 《Singapore journal of tropical geography》2009,30(1):140-141

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High Velocity Clouds in the Galaxy     

Felix J. Lockman 《Astrophysics and Space Science》1999,267(1-4):139-143

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An absolute calibration site for radar altimeters in the continental domain: Lake Issykkul in Central Asia     

Jean-François Crétaux  Stephane Calmant  Vladimir Romanovski  Anton Shabunin  Florent Lyard  Muriel Bergé-Nguyen  Anny Cazenave  Fabrice Hernandez  Felix Perosanz 《Journal of Geodesy》2009,83(8):723-735

Altimetry missions such as Topex/Poseidon, Jason-1, GFO and ENVISAT have been widely used in the continental domain over lakes, rivers and wetland although they were mostly dedicated to oceanic studies. Knowledge of the instrumental biases is a key issue. Numerous sites have been dedicated to calibration purposes, either in the oceanic domain (Harvest offshore platform in California, Corsica, Bass Strait in Australia) or over lakes (Lake Erie in United States). A new site (Lake Issykkul in Kirghizstan) is proposed for calibration in the continental domain. This lake is covered by past (T/P) and current radar altimetry satellites (Jason-1, T/P, GFO, and ENVISAT). Several in situ water levels and local meteorological variables are available at the site. Located in a mountainous area, it offers an opportunity for calibration far away from all other existing sites and very different environment contexts. Two GPS campaigns have been conducted on the lake in 2004 and in 2005. They consisted of cruises with stations installed onboard a boat following the satellite ground tracks, and onshore settings. This enabled estimating a bias for each altimeter and each tracking algorithm available. Biases obtained for Envisat, GFO, T/P and Jason-1 using the default ocean tracker (respectively, 48.1 ± 6.6, 7.5 ± 4.0, 0 ± 4.3 and 7.0 ± 5.5 cm) agree with biases published at the other calibration sites. For Jason-1, there is a significant disagreement with results obtained in the ocean field (7 cm instead of 13 cm) but is coherent with bias obtained on the Lake Erie site. Erroneous estimates of the sea state bias correction from non-oceanic-like waveforms is discussed as a possible explanation. Errors in the ionospheric, wet and dry tropospheric corrections for the continental domain are also highlighted and quantified.  相似文献   

A generic approach to modelling flexible confined boundary conditions in SPH and its application     

Shaohan Zhao  Ha H. Bui  Vincent Lemiale  Giang D. Nguyen  Felix Darve 《国际地质力学数值与分析法杂志》2019,43(5):1005-1031

In this paper, a new approach to applying confining stress to flexible boundaries in the smoothed particle hydrodynamics (SPH) method is developed to facilitate its applications in geomechanics. Unlike the conventional SPH methods that impose confining boundary conditions by creating extra boundary particles, the proposed approach makes use of kernel truncation properties of SPH approximations that occur naturally at free-surface boundaries. Therefore, it does not require extra boundary particles and, as a consequence, can be utilised to apply confining stresses onto any boundary with arbitrary geometry without the need for tracking the curvature change during the computation. This enables more complicated problems that involve moving confining boundaries, such as confining triaxial tests, to be simulated in SPH without difficulties. To further enhance SPH applications in elasto-plastic computations of geomaterials, a robust numerical procedure to implement Mohr-Coulomb plasticity model in SPH is presented for the first time to avoid difficulties associated with corner singularities in Mohr-Coulomb model. The proposed approach was first validated against two-dimensional finite element (FE) solutions for confining biaxial compression tests to demonstrate its predictive capability at small deformation range when FE solutions are still valid. It is then further extended to three-dimensional conditions and utilised to simulate triaxial compression experiments. Simulation results predicted by SPH show good agreement with experiments, FE solutions, and other numerical results available in the literature. This suggests that the proposed approach of imposing confining stress boundaries is promising and can handle complex problems that involve moving confining boundary conditions.  相似文献   

Dark matter annihilation in the halo of the Milky Way     

Felix Stoehr  Simon D. M. White  Volker Springel  Giuseppe Tormen  Naoki Yoshida 《Monthly notices of the Royal Astronomical Society》2003,345(4):1313-1322

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