水产膨化饲料

本文综述了水产膨化饲料的优势、加工原理、膨化对营养素的影响、投喂技术和投喂海水养殖鱼类的试验结果.     

VTI介质中弹性波方程正演的一阶混合吸收边界

波动方程正演是研究地震波在地下介质中的传播机理以及提高地震资料采集、处理、解释精度和效果的重要工具,截断边界的处理是波动方程正演的重要研究内容。针对在地震数值模拟中常用的三种(吸收)边界处理方法存在的不足与问题,提出了适用于VTI介质中弹性波动方程正演的一阶混合吸收边界条件,并给出了该方法在过渡区域的线性叠加系数公式。数值模拟实验表明:相同条件下,VTI介质一阶混合吸收边界方法不仅在吸收效果方面优于常规的PML边界条件,而且在存储量和计算效率方面也具有较大优势。     

Set-asides for carbon sequestration: implications for permanence and leakage

This paper examines the potential role of forest set-asides in global carbon sequestration policy. While set asides that protect forests from timber harvests and land-use conversion may alleviate concerns with permanence, and they may provide large ancillary environmental benefits, they may also lead to large leakage. This paper uses a global land use and forestry model to examine the efficiency of three crediting schemes for set-asides. The results show that if set-asides are integrated into a global forestry carbon sequestration program that includes a wide range of other management options, then 300 million hectares of land would be set-aside, and up to 128 Pg C could be sequestered in global forests by 2105. Under alternative policies that focus exclusively on set-asides, more forestland can be set-asides, up to 3.2 billion hectare, but these policies invite large leakage in the near-term, and in the long-run, they less net carbon is removed from the atmosphere. Specifically, leakage is estimated to be 47–52%, depending on the policy, and by the end of the century, up to 17% less carbon will be sequestered in all forests.     

Geochemical characteristics of sphagnum brown coal — A possible oil-generating precursor

A preliminary study of newly discovered sphagnum brown coal from the Jingsuo Basin, Yunnan Province, China, which is quite rich in montan wax, indicates the predominance of highern-alkane homologues and aromatized triterpenoid components. Aromatic hydrocarbons are composed mainly of pentacyclic and tetracyclic di-, tri- and tetra-aromatic components, which are obviously diagenetically related to higher plant-derived triterpenoids naturally occurring in the biosphere. Because the sphagnum brown coal still remains in the highly immature stage, it seems that the progressive diagenetic aromatization of the higher plant-derived triterpenoids may start at a very early stage.     

Electrical conductivity of hydrous silicate melts and aqueous fluids: Measurement and applications

The combination of magnetotelluric survey and laboratory measurements of electrical conductivity is a powerful approach for exploring the conditions of Earth’s deep interior. Electrical conductivity of hydrous silicate melts and aqueous fluids is sensitive to composition, temperature, and pressure, making it useful for understanding partial melting and fluid activity at great depths. This study presents a review on the experimental studies of electrical conductivity of silicate melts and aqueous fluids, and introduces some important applications of experimental results. For silicate melts, electrical conductivity increases with increasing temperature but decreases with pressure. With a similar Na⁺ concentration, along the calc-alkaline series electrical conductivity generally increases from basaltic to rhyolitic melt, accompanied by a decreasing activation enthalpy. Electrical conductivity of silicate melts is strongly enhanced with the incorporation of water due to promoted cation mobility. For aqueous fluids, research is focused on dilute electrolyte solutions. Electrical conductivity typically first increases and then decreases with increasing temperature, and increases with pressure before approaching a plateau value. The dissociation constant of electrolyte can be derived from conductivity data. To develop generally applicable quantitative models of electrical conductivity of melt/fluid addressing the dependences on temperature, pressure, and composition, it requires more electrical conductivity measurements of representative systems to be implemented in an extensive P-T range using up-to-date methods.     

Recession of Milam Glacier,Kumaun Himalaya,Observed via Lichenometric Dating of Moraines

Glaciers being very sensitive to climate change have been identified as one of the best indicators of climate change and evidences have proved that most of the Himalayan glaciers have receded with an increased rate during the recent past under the influence of global warming. Lichenometric study was carried out on the moraines of Milam glacier (located in Pithoragarh district of Uttarakhand) with the help of lichen species Dimelaena oreina having an average annual growth rate of 1.31 mm. The study revealed that Milam glacier has receded 1450 m in last 69.37 years with an average recession rate of 20.90 m/year. Since lichenometric studies are cost effective and ecofriendly in comparison to carbon dating, satellite and remote sensing based studies and also reliable, hence, it should be promoted in Himalaya which is an abode of glaciers.     

浅析云峰井变径前后气压效应与井径比的关系

本文通过改变云峰井孔径试验,探讨了提高地下水观测井映震能力的一种途径。     

Effect of a nodular segment on the dynamic response of a tubular pile subjected to longitudinal vibration

Acta Geotechnica - This paper investigates the effect of a nodular segment, commonly found in nodular piles, on the dynamic response of a vertical vibrating tubular pile. A developed model of a...     

http://www.sciencedirect.com/science/article/pii/S1674987110000058

<正>The thermo-electric coefficients of twenty-six magnetite samples,formed either by magmatism or metamorphism,were tested by the thermo-electric instrument BHET—06.Results showed that the coefficient is of a constant value of about -0.05 mV/℃.It is emphasized that because every magnetite grain was tested randomly,the coefficient is independent of the crystallographic direction.This fact means the thermal voltage generated from a single magnetite crystal can be accumulated,and as a result a new thermo-electric field can arise when a gradient thermal field exists and is active within the earth's crust.Because magnetite is widespread in the earth's crust(generally appearing more in the middle-lower crust),there is more-than-random probability that the additional thermo-electric field can be generated when certain thermal conditions are fulfilled.We,therefore,used the thermo-electric effect of magnetite to study the mechanism responsible for the presence of abnormal geo-electric fields during earthquake formation and occurrence, because gradient thermal fields always exist before earthquakes.The possible presence of additional thermo-electric fields was calculated under theoretical seismological conditions,using the following calcu-lation formula:E= - 0.159(σ×△T×φ×ρ_2×[(h~2-2x~2)cosα+ 3hxsinα]/ρ_1(h~2 +x~2)~(5/2)).In the above formula,σis thermo-electric coefficient of magnetite,△T is the temperature difference acting on it,φis a sectional area on a block of magnetite vertically perpendicular to the direction of the thermal current.ρ_1 andρ_2 are the respective resistivities of magnetite and the crust,and h,α,and x,respectively,h is the depth of embedded magnetite block,αmeans the angle created by the horizontal line and ligature of the two poles of magnetite block,and x is the distance from observation point to projective center point of the magnetite block on earth surface.According to simulations calculated with this formula,additional thermo-electric field intensity may reach as high as n to n×10~2 mV/km.This field is strong enough to cause obvious anomalies in the background geo-electric field,and can be easy probed by earthquake monitoring equipment. Therefore,we hypothesize that geo-electric abnormalities which occur during earthquakes may be caused by the thermo-electric effect of magnetite.     

High resolution facies record on late Holocene flood plain sediments from lower reaches of Narmada Valley,Western India

A high resolution quantitative granulometric record for site Uchediya [21°43′2.22″ N, 73° 6′26.22″ E; 10 m a. s. l.] gives understanding towards accretion history of the late Holocene flood plain in the lower reaches of Narmada River. Two sediment facies (sandy and muddy) and seven subfacies (sandy subfacies: St_MS+FS+CS, Sm_FS+MS, Sl_FS+VFS, and St_{MS + CS}; muddy subfacies: Fm_SILT+VFS+FS, Fm_SILT+VFS (O) and Fm_SILT+VFS (T)) are identified based on cluster analysis supplemented with sedimentary structures observed in field and other laboratory data. Changes in hydrodynamics are further deduced based on various sedimentological parameters and their ratios leading to arrive at a depositional model.