One-dimensional,semi-analytical solution for time-dependent behaviour of a seam     

Pawel A. Nawrocki 《国际地质力学数值与分析法杂志》1995,19(1):59-74

The paper provides a one-dimensional, semi-analytical study of face advance in a coal seam assuming a Bingham type of material model. The changes in vertical stress and deformation in the seam due to change in the geometric configuration of the excavation are analysed. The general analytical formulae defining stresses and strains for an arbitrary time instant i Δt(i = 1,2,…) are derived, and the size of the viscoplastic zone near the opening and its evolution with time are determined. The influence of the seam extraction rate on the stability of the seam and rock burst occurrence is discussed in the light of the developments presented in this paper.  相似文献   

Heterochromatin and NOR location in northern pike (Esox lucius)   总被引：2，自引：0，他引：2  

Malgorzata Jankun  Pawel Woznicki  Grzegorz Dajnowicz  Krystyna Demska-Zakes  Marek J. Luczynski  Miroslaw Luczynski 《Aquatic Sciences - Research Across Boundaries》1998,60(1):17-21

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P–SVmultimode summation differential seismograms for layered structures     

Z. J. Du  A. Michelini  G. F. Panza  & L. Urban 《Geophysical Journal International》1998,134(3):747-756

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A Bayesian machine learning model for estimating building occupancy from open source data     

Robert Stewart  Marie Urban  Samantha Duchscherer  Jason Kaufman  April Morton  Gautam Thakur  Jesse Piburn  Jessica Moehl 《Natural Hazards》2016,81(3):1929-1956

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Synthetic polyacrylamide as a potential flocculent to remove commercial chromium(III) oxide from aqueous suspension     

M. Wiśniewska  S. Chibowski  T. Urban 《International Journal of Environmental Science and Technology》2016,13(2):679-690

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State-of-the-art overview of the Loess Palaeolithic of Poland     

Pawel Valde-Nowak  Maria łAnczont 《第四纪科学杂志》2021,36(8):1341-1352

In Poland, loess mainly occurs in the southern part of the country, in the Polish Uplands, and on the northern foreland of the Sudetes and the Carpathians. Most of these sediments come from the time of the last glaciation–the Vistulian (Weichselian) glaciation. Thin covers of loess from the penultimate glaciation have been preserved in Upper Silesia. Only a few sites from the Middle Palaeolithic remain in the loess. In the eastern part of Poland loess creates profiles several metres high. Discoveries in this zone represent the cultural sequence from the transition from the Middle to Upper Palaeolithic. We know more traces of various cultures from the Upper Palaeolithic exist. The study attempts to synchronise profiles from selected archaeological open-air sites, outlines of the history of research on loess sites, and attempts to explain terminological and conceptual issues. The issue of loess in the cave site profiles will not be discussed in the article.  相似文献   

Experimental Researches on Reflective and Transmitting Performances of Quarter Circular Breakwater Under Regular and Irregular Waves     

史艳娇  吴米玲  蒋学炼  李炎保 《中国海洋工程》2011,(3)

A series of regular and irregular wave experiments are conducted to study the reflective and transmitting performances of quarter circular breakwater (QCB) in comparison with those of semi-circular breakwater (SCB). Based on regular wave tests, the reflection and transmission characteristics of QCB are analyzed and a few influencing factors are investigated. Then, the wave energy dissipation as wave passing over the breakwater is discussed based on the hydraulic coefficients of QCB and SCB. In irregular wav...  相似文献   

Search for shadowing of primary cosmic radiation by the moon at TeV energies     

D. Pomarde  P. J. Boyle  M. Urban  H. M. Badran  L. Behr  M. T. Brunetti  D. J. Fegan  T. C. Weekes 《Astroparticle Physics》2001,14(4)

The antimatter research through the earth moon ion spectrometer (ARTEMIS) experiment is described in terms of searching for the moon's shadow in the primary cosmic radiation at TeV energies. Observations were made using the Whipple 10 m Imaging Atmospheric erenkov Telescope, in conjunction with a special optical filter to suppress unwanted moonlight. Monte Carlo simulations were used to predict that the magnitude of shadowing based on a pure proton beam would be 1% of the cosmic ray background. Observations and event classification are discussed, and results of a search for shadowing based on both protons and antiprotons are presented. Atmospheric fluctuations giving rise to non-statistical event rates constituted a limiting factor to the sensitivity of the shadow search as they rivaled or exceeded statistical errors. It is demonstrated that the experiment does not have sufficient sensitivity to moon shadowing which would allow a search for an antimatter component in the primary cosmic ray flux at the percent level. Possible future improvements of the technique are discussed.  相似文献   

Ionospheric electron density observed by FORMOSAT-3/COSMIC over the European region and validated by ionosonde data   总被引：4，自引：0，他引：4  

Andrzej Krankowski  Irina Zakharenkova  Anna Krypiak-Gregorczyk  Irk I. Shagimuratov  Pawel Wielgosz 《Journal of Geodesy》2011,85(12):949-964

This research is motivated by the recent IGS Ionosphere Working Group recommendation issued at the IGS 2010 Workshop held in Newcastle, UK. This recommendation encourages studies on the evaluation of the application of COSMIC radio occultation profiles for additional IGS global ionosphere map (GIM) validation. This is because the reliability of GIMs is crucial to many geodetic applications. On the other hand, radio occultation using GPS signals has been proven to be a promising technique to retrieve accurate profiles of the ionospheric electron density with high vertical resolution on a global scale. However, systematic validation work is still needed before using this powerful technique for sounding the ionosphere on a routine basis. In this paper, we analyze the properties of the ionospheric electron density profiling retrieved from COSMIC radio occultation measurements. A comparison of radio occultation data with ground-based measurements indicates that COSMIC profiles are usually in good agreement with ionosonde profiles, both in the F2 layer peak electron density and the bottom side of the profiles. For this comparison, ionograms recorded by European ionospheric stations (DIAS network) in 2008 were used.  相似文献   

Assessment of GPS + Galileo and multi-frequency Galileo single-epoch precise positioning with network corrections   总被引：1，自引：0，他引：1  

Jacek Paziewski  Pawel Wielgosz 《GPS Solutions》2014,18(4):571-579

Several processing strategies that use dual-frequency GPS-only solution, multi-frequency Galileo-only solution, and finally tightly combined dual-frequency GPS + Galileo solution were tested and analyzed for their applicability to single-epoch long-range precise positioning. In particular, a multi-system GPS + Galileo solution was compared to GPS double-frequency solution as well as to Galileo double-, triple-, and quadruple-frequency solutions. Also, the performance of the strategies was analyzed under clear-sky and obstructed satellite visibility in both single-baseline and multi-baseline modes. The results indicate that tightly combined GPS + Galileo instantaneous positioning has a clear advantage over single-system solutions and provides an accurate and reliable solution. It was also confirmed that application of multi-frequency observations in case of Galileo system has an advantage over a dual-frequency solution.  相似文献