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Cosmic energy equation is an important equation for studying the gravitational galaxy clustering in the expanding universe.
We derive the distribution function for fluctuations in particle number by using the cosmic energy equation for extended structures
(galaxies with halos). From spatial distribution function, containing particle fluctuations, we derive the velocity distribution
function to understand the influence of particle fluctuations on the velocities of galaxies.With the help of cosmic energy
equation we try to find out the physical constraints for the application of quasi-equilibrium approximation. 相似文献
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Rock reinforcement systems, such as resin-grouted rock bolts, display complex creep behavior because both grouting materials and bolts show time-dependent behavior. In this paper, only the time-dependent behavior of grouting material was investigated, in which creep tests of grouting material was conducted in triaxial compression apparatus at room temperature. The test specimens were provided from the Araldite epoxy resin used in rock reinforcement. We attempt to predict long-term creep parameter using triaxial creep tests and to define time-dependent characteristics of the bounding material. In short-term creep tests, three different axial and confining stress levels were applied in steps to each specimen. The transient creep for all the stress levels were described by power function which fit properly to time–strain curves. The maximum difference between the proposed model and experimental long-term creep strain was less than 7.1 %. It was observed that the creep rate of a grouting material specimen directly depends on the deviator of stress (i.e., σ1–σ3). 相似文献
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Application of Fuzzy Set Theory to Rock Engineering Classification Systems: An Illustration of the Rock Mass Excavability Index 总被引:1,自引:0,他引:1
Jafar Khademi Hamidi Kourosh Shahriar Bahram Rezai Hadi Bejari 《Rock Mechanics and Rock Engineering》2010,43(3):335-350
The characterization of rock masses is one of the integral aspects of rock engineering. Over the years, many classification
systems have been developed for characterization and design purposes in mining and civil engineering practices. However, the
strength and weak points of such rating-based classifications have always been questionable. Such classification systems assign
quantifiable values to predefined classified geotechnical parameters of rock mass. This results in subjective uncertainties,
leading to the misuse of such classifications in practical applications. Fuzzy set theory is an effective tool to overcome
such uncertainties by using membership functions and an inference system. This study illustrates the potential application
of fuzzy set theory in assisting engineers in the rock engineering decision processes for which subjectivity plays an important
role. So, the basic principles of fuzzy set theory are described and then it was applied to rock mass excavability (RME) classification
to verify the applicability of fuzzy rock engineering classifications. It was concluded that fuzzy set theory has an acceptable
reliability to be employed for all rock engineering classification systems. 相似文献
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Here Rydberg matter is proposed as a candidate for the missing dark matter or dark baryonic matter in the Universe. Spectroscopic and other experimental studies give valuable information on the properties of Rydberg matter, especially its very weak interaction with light caused by the very small overlap with low states, and because of the necessary two-electron transitions even for disturbed matter. Recently, the unidentified infrared (UIR) bands have been shown to agree well with calculations and experiments on Rydberg matter. This is the reason for the present, somewhat speculative, proposal that dark matter has, at least partially, the form of Rydberg matter. The UIR bands have also been observed directly in emission from Rydberg matter in the laboratory. The unique space-filling properties of Rydberg matter are described: a hydrogen atom in this matter occupies a volume 5×1012 times larger than in its ground state or in a hydrogen molecule. 相似文献
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Studying the stress redistribution around the longwall mining panel using passive seismic velocity tomography and geostatistical estimation 总被引:3,自引:0,他引:3
Navid Hosseini Kazem Oraee Kourosh Shahriar Kamran Goshtasbi 《Arabian Journal of Geosciences》2013,6(5):1407-1416
Generally, knowledge of stress redistribution around the longwall panel causes a better understanding of the mechanisms that lead to ground failure, especially to rockbursts. In this paper, passive seismic velocity tomography is used to demonstrate the state of stress around the longwall mining panel. The mining-induced microseismic events were recorded by mounting an array of receivers on the surface, above the active panel. To determine the location of seismic events and execute the process of tomography, double-difference method is employed as a local earthquake tomography. Since passive sources are used, the ray coverage is insufficient to achieve the quality images required. The wave velocity is assumed to be the regionalized variable and it is therefore estimated in a denser network, by using geostatistical estimation method. Subsequently, the three-dimensional images of wave velocity are created and are sliced into the coal seam. These images clearly illustrate the stressed zones that they are appropriately in compliance with the theoretical models. Such compliance is particularly apparent in the front abutment pressure and the side abutment pressure near the tailgate entry. Movements of the stressed zones along the advancing face are also evident. The research conclusion proves that the combined method, based on double-difference tomography and geostatistical estimation, can potentially be used to monitor stress changes around the longwall mining panel continuously. Such observation could lead to substantial improvement in both productivity and safety of mining operations. 相似文献
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Livelihood diversification as an adaptation approach to change in the pastoral Hindu-Kush Himalayan region 总被引:1,自引:0,他引:1
Ning Wu Muhammad Ismail Srijana Joshi Shao-liang Yi Ritu Meher Shrestha Abdul Wahid Jasra 《山地科学学报》2014,11(5):1342-1355
Migratory livestock raising has been one of the most important livelihood options for people residing in high mountain areas and has made a significant contribution to the economy of the Hindu Kush Himalayan(HKH) region, both in terms of supporting households and in export earnings. However, in recent decades, changes in the socioeconomic situation and increasing climate variability have led to a need to enhance adaptation by building the resilience of local socio-ecological systems, including economic diversification and sustainable management of natural resources. Based on semistructured interviews with pastoral communities in six countries within the pastoral HKH region, this paper discusses the situation, trends and driving forces behind the diversification of pastoral livelihood. For internal diversification the study highlights the need for enhancement of pastoral livelihoods through value-adding activities in the pastoral sectors. For external diversification changes on policy changes are needed to support free out-migration, market exploitation, and multiple resource use. Finally the paper highlights the role of education in determining household adaptation strategies in the face of various socio-ecological pressures and recommends integrating innovative and indigenous knowledge to develop appropriate methods for risk management and resource management in the pastoral HKH region. 相似文献
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Fardin Sadegh‐Zadeh Abd Wahid Samsuri Othman Radziah Omar Dzolkhifli Bahi Jalili Seh‐Bardan 《洁净——土壤、空气、水》2012,40(6):599-606
The degradation and leaching of napropamide were compared between Beach Ridges Interspersed with Swales (BRIS) soil samples, and the same soil samples amended with 20 mg ha?1 of either chicken dung (CD) or palm oil mill effluent (POME). The effects of removing dissolved organic carbon (DOC) from the soil samples on napropamide degradation and leaching were also studied. The addition of CD and POME to BRIS soil increased the napropamide half‐life values to 69 and 49.5 days, respectively. Sterilization of the soil samples resulted in partial inhibition of napropamide degradation in all soil samples. The half‐lives of napropamide in BRIS soils receiving 0, 20, 100, and 200 mg kg?1 of DOC derived from CD were 43, 46.2, 53.4, and 63 days, respectively. The napropamide half‐lives in soil samples treated with 0, 20, 100, and 200 mg kg?1 of DOC derived from POME were 43, 49.2, 57.7, and 69 days, respectively. However, in the sterilized soil samples, there were no significant effects of adding DOC derived from either CD or POME on napropamide half‐lives. Incorporating either CD or POME decreased napropamide leaching and total amounts of napropamide remained in the soil columns after two pore volumes of water has been leached were higher in the amended than the non‐amended soil. The CD was more effective in decreasing napropamide leaching than the POME. There were no effects of DOC on napropamide leaching in all soil treatments. 相似文献
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Mohammadreza Gharibreza Mohammad Zaman Mahmood Arabkhedri Shahriar Sobh-Zahedi 《国际泥沙研究》2022,37(3):370-382
Abkenar open water(AOW)has a 35 km2distribution and is the largest part of the Anzali Lagoon in the southern coastal zone of the Caspian Sea.The effects of deforestation in the upstream basin of the AOW were assessed by measuring the rate of sedimentation,sediment contamination,and ecological risk for aquatic life and end-users using radioisotopes Cesium-137 and Lead-210.The chronology of the AOW sediment column was studied using the Constant Rate of Supply model.Correlations between environmental changes and the sedimentary regime of the study area highlight the contribution of the AOW authorized international and local wood harvesting companies pre-and-post 1950 in the catchment in terms of the rate of sediment supply and the influx of toxic metals.Historical evidence shows that two specific layers formed during World Wars I and II with the mean rates of 0.185±0.04(±STD)and 0.32±0.02 kg/(m2·y),respectively.The highest influx of alkali elements and toxic metals(nickel,cadmium,lead,zinc,and copper)into the basin occurred in 1945.Two layers of gray mud(16-50 cm)and organic-rich dark loss mud(0-16 cm)correlated well with the programmed wood harvesting projects.These layers accumulated from 1953 to 2000 with a mean rate of 0.6±0.2 and 2±0.7 kg/(m2·y).Thus,aquatic life and end-users have been exposed to moderate to extremely high levels of toxic metals and a moderate level of contamination since the 1950s. 相似文献