On the applicability of KirchofPs law and the principle of heat balance in thermal infrared remote sensing:A non-isothermal system     

ZHANG Renhua  LI Zhaoliang  SUN Xiaomin  ZHU Zhilin & WANG Weimin Institute of Geographical Sciences  Natural Resources Research  Chinese Academy of Sciences  Beijing  China  LSIIT 《中国科学D辑(英文版)》2005,(1)

This paper proposes a basic equation of thermal radiation interaction between surface objects on the basis of the principle of heat balance in the interface. The solution of this equation takes account of the contribution of sensible heat flux and latent heat flux more completely, compared with traditional solution for surface cooling and heating processes. By the aid of the experimental data conducted in the Xiaotangshan experimental site, Beijing, both the non-applicability of Kirchoff's law and the measurability of surface emissivity in a non-isothermal system have been highlighted. Two methods called ventilation and time-delay compensations have been proposed to reduce the error induced by change of surface temperatures of non-isothermal objects during the measurement of emissivity. Based on the solution of the basic equation, this paper has analyzed and pointed out the misunderstanding in comprehension and application of Kirchoff's law published in literature.  相似文献   

Effect of suction on the mechanical behaviour of iron ore rock   总被引：1，自引：0，他引：1  

Dragan Grgic  Richard Giot  Franoise Homand  Albert Giraud 《国际地质力学数值与分析法杂志》2005,29(8):789-827

The effect of suction on the behaviour of iron ore has been studied from both physical and mechanical points of view. The porosity and the suction phenomena have been analysed using different experimental techniques. Uniaxial compressive tests on partially saturated samples have shown that the suction is responsible for strength and cohesion improvement. Considering the theory of partially saturated porous soils of Coussy and Dangla (Mécanique des sols non saturés (2002 edn). Hermès Science: 2002; 390), we have proposed a constitutive law for partially saturated iron ore. The real increase in the apparent cohesion due to the capillary attraction forces is overestimated if the yield function is written in terms of effective stresses. The effect of the capillary cohesion has been modelled with a function in the expression of the apparent cohesion of the yield function. The effect of suction on the mechanical behaviour has been represented in the effective stresses space and in the total stresses space like the Alonso model (Géotechnique 1990; 40 :405–430). Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

An approach to model the mechanical behavior of transversely isotropic materials          下载免费PDF全文

M. Mahjoub  A. Rouabhi  M. Tijani  S. Granet 《国际地质力学数值与分析法杂志》2016,40(6):942-961

The present work proposes an approach to adapt existing isotropic models to transversely isotropic materials. The main idea is to introduce equivalence relations between the real material and a fictitious isotropic one on which one can take all the advantages of the well‐established isotropic theory. Two applications of this approach are presented here: a failure criterion and a damage model that takes into account the load‐induced anisotropy. In both cases, theoretical predictions are in agreement with the experimental data. In the present paper, the developed approach is applied to sedimentary rock materials; nevertheless, it can be generalized to any material that exhibits transverse isotropy. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Are peatlands in different states with respect to their thermodynamic behaviour? A simple test of peatland energy and entropy budgets     

Fred Worrall  Ross Morrison  Chris Evans  Joerg Kaduk  Susan Page  Alex Cumming  Mark Rayment  Nicholas Kettridge 《水文研究》2021,35(12):e14431

Whilst all ecosystems must obey the second law of thermodynamics, these physical bounds and controls on ecosystem evolution and development are largely ignored across the ecohydrological literature. To unravel the importance of these underlying restraints on ecosystem form and function, and their power to inform our scientific understanding, we have calculated the entropy budget of a range of peat ecosystems. We hypothesize that less disturbed peatlands are ‘near equilibrium’ with respect to the second law of thermodynamics and thus respond to change by minimizing entropy production. This ‘near equilibrium’ state is best achieved by limiting evaporative losses. Alternatively, peatlands ‘far-from-equilibrium’ respond to a change in energy inputs by maximizing entropy production which is best achieved by increasing evapotranspiration. To test these alternatives this study examined the energy balance time series from seven peatlands across a disturbance gradient. We estimate the entropy budgets for each and determine how a change in net radiation (ΔR_n) was transferred to a change in latent heat flux (ΔλE). The study showed that: (i) The transfer of net radiation to latent heat differed significantly between peatlands. One group transferred up to 64% of the change in net radiation to a change in latent heat flux, while the second transferred as little as 27%. (ii) Sites that transferred the most energy to latent heat flux were those that produced the greatest entropy. The study shows that an ecosystem could be ‘near equilibrium’ rather than ‘far from equilibrium’.  相似文献   

On the dependence of the saturated hydraulic conductivity upon the effective porosity through a power law model at different scales          下载免费PDF全文

Carmine Fallico  Samuele De Bartolo  Massimo Veltri  Gerardo Severino 《水文研究》2016,30(13):2366-2372

We study the scale dependence of the saturated hydraulic conductivity K_s through the effective porosity n_e by means of a newly developed power‐law model (PLM) which allows to use simultaneously measurements at different scales. The model is expressed as product between a single PLM (capturing the impact of the dominating scale) and a characteristic function κ^? accounting for the correction because of the other scale(s). The simple (closed form) expression of the κ^?‐function enables one to easily identify the scales which are relevant for K_s. The proposed model is then applied to a set of real data taken at the experimental site of Montalto Uffugo (Italy), and we show that in this case two (i.e. laboratory and field) scales appear to be the main ones. The implications toward an important application (solute transport) in Hydrology are finally discussed. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

电涌保护器级间退耦元件的选型分析     

王成芳  刘冲  罗达标  余佥贤  王昊 《南京气象学院学报》2016,8(4):338-342

针对电涌保护器（SPD）级间能量配合试验中配合失效的问题,主要利用波的传输理论与基尔霍夫定律进行分析,结合JB/T 10618-2006（组合式电涌保护器）的规定假设一套组合型SPD,通过基础理论分析与精确计算得出：当被保护装置属于低频（直流）设备时,在不影响信号强度的情况下,退耦元件采用电感或电阻型元件均可;当被保护装置属于高频设备时,退耦元件只能选用低电感量的电阻型退耦元件.退耦元件的参数值均可按照波的传输理论与基尔霍夫定律进行理论计算.这在组合型SPD退耦元件的选型过程中,具有重要的指导意义.  相似文献   

南岭钨矿床研究进展     

方贵聪  陈远荣  刘奕志  陈郑辉  赵正  郭娜欣 《矿产与地质》2016,(6):867-873

南岭钨矿床研究一直是重要的前沿课题,近十余年来测试方法和技术的革新为南岭钨矿床研究注入了新活力,也取得了众多新进展.本文在系统查阅前人研究基础上对其进行总结,概括如下:①该区的岩浆-钨成矿活动不仅有燕山期,也有加里东期和印支期,但以燕山期最为强烈;②花岗岩浆是南岭钨矿床主要的直接物质来源,即使有少部分成矿物质是热液直接对含矿地层淋滤、萃取而来,但却被认为是次要的;③与花岗岩有关钨矿床的成矿流体主要来自花岗岩浆,在成矿作用晚期有不同程度的大气降水混入;④与钨有关的花岗岩主要由下地壳的早—中元古代岩石重熔形成,但地幔岩浆一定程度上参与了花岗岩的形成作用;⑤碱质交代在花岗岩浆演化形成钨矿床的过程中发挥了关键性作用;⑥不同学者对燕山期钨成矿作用动力学背景尚有不同看法,但该时期确定为板内伸展和裂谷环境已达成共识.  相似文献   

北祁连地区中寒武世岩相古地理研究          下载免费PDF全文

谭志远  牟传龙  王启宇  陈小炜  葛祥英  侯乾 《沉积与特提斯地质》2016,36(1):55-61

现今地处造山带的北祁连地区在中寒武世时期拉张的构造背景下海域进一步拓宽。通过对北祁连地区中寒武统地层野外调查及室内分析研究,在"构造控盆、盆控相"的思路控制下,以沉积岩性、结构-构造、古生物组合等为基础,在优势相原则的指导下,共划分出浅海陆棚相、半深海相、深海盆地相3种沉积相类型。结合前人的研究资料,编制北祁连地区中寒武世的沉积构造格架及沉积盆地类型图,分析其空间配置关系。在此基础上,采用造山带岩相古地理编图方法,恢复与重建研究区的古地理面貌,编制相应的古地理图。  相似文献   

The international legal framework for the management of the global oceans social-ecological system     

《Marine Policy》2016

This paper evaluates the international agreements in place for the protection of the environment and the regulation of human activities taking place in world's oceans and seas. 500 multilateral agreements were reviewed against a framework of reference, grounded on the theoretical approaches of Adaptive Management and Transition Management. According to this framework, oceans complex systems management should: (1) consider the global oceans as a Social-Ecological System (SES); (2) aim to achieve or maintain their ecological resilience; and (3) implement iterative, learning-based management strategies, supported by science-based advice to policy and management. The results show that the present international legal framework for the global oceans does not require countries to adopt an adaptive, complex systems approach for global oceans ecological resilience. Instead, this study supports the perspective of a double fragmentation among international agreements. First, global agreements focus on issue-based objectives for determined human activities, ecological components or anthropogenic pressures. Second, regional agreements have a wider scope, but also a varying level of inclusion of ecological resilience considerations. There is the need to foster the inclusion of such an approach into existing and future international agreements and their implementation, including through soft-law, project-based initiatives at global and regional scales.  相似文献   

Rainfall flood hazard at nuclear power plants in India     

Pramod Kumar Sharma 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2018,12(3):218-233

Flood hazard evaluation is an important input for Nuclear Power Plants external events safety studies. In the present study, flood hazard at various nuclear sites in India due to rainfall has been evaluated. Hazard estimation is a statistical procedure by which rainfall intensity versus occurrence frequency is estimated from historical records of rainfall data and extrapolated with asymptotic extreme value distribution. Rainfall data needed for flood hazard assessment are daily annual maximum rainfall (24?h data). The observed data points have been fitted using Gumbel, power law and exponential distribution, and return period has been estimated. To study the stationarity of rainfall data, a moving window estimate of the parameters has been performed. The rainfall pattern is stationary in both coastal and inland regions over the period of observation. The coastal regions show intense rainfall and higher variability than inland regions. Based on the plant layout, catchment area and drainage capacity, the prototype fast breeder reactor (PFBR) site is unlikely to be flooded.  相似文献