Loading on a cylinder in uniform oscillatory flow: Part II— Elliptical orbital flow     

John R. Chaplin 《Applied Ocean Research》1988,10(4):199-206

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环形控制网中各观测量的极坐标误差方程     

邓雪清  黄桂平 《测绘学院学报》1998,(1)

针对环形控制网的网形特点 ,推导了各类观测量 :测边、测方向和测高的极坐标误差方程式。  相似文献   

圆形建筑物的测绘方法     

周扬眉  黄文治 《测绘与空间地理信息》1998,(2)

本文就如何测绘圆形建筑物平面图形的问题,作者提出了两种计算方法,即极坐标测绘法和直角坐标法;并推导出了用这两种方法计算圆心位置和半径的公式。  相似文献   

Conceptualizing and achieving industrial system transition for a dematerialized and decarbonized world     

《Global Environmental Change》2021

The concept of industrial system transition introduced in the IPCC special report on Global Warming of 1.5 °C remains poorly conceptualized. In this paper, we deepen the conceptualization of the industrial system transition to decarbonization, dematerialization, and sustainable industrial production. Aided by fuzzy cognitive maps that use perception-based data from stakeholders to model complex and difficult-to-model systems, we chart the pathways for industrial system transition. The industrial system transition entails interactions between dematerialization and decarbonization goals while enabling governance and systemic corporate strategies. The respondents of the fuzzy cognitive maps-based surveys comprised practitioners from companies, authors, and the policymaking community. Fuzzy cognitive map-based simulations reveal that resorting to technical measures of dematerialization and decarbonization is insufficient to accomplish industrial system transition. The efficient industrial system transition to dematerialization and decarbonization requires the combined measures of (i) dematerialization and decarbonization, (ii) governance, policies, and regulations (effective governance including transnational governance, technology push, market-pull, technology transfer and financial flows, carbon price and carbon market; and (iii) enabling corporate strategies (regenerative and conscious capitalism, a new conception of transparency, and collaborative and constructive lobbying). Large companies are mostly transnational entities, necessitating the adoption of effective transnational governance strategies for achieving the objectives of dematerialization and decarbonization. Several transnational governance networks have partnered under the public–private co-governance mechanism in the decarbonization space dominated by mainly larger players. The advent of polycentric governance provides new opportunities for trans-local governance where large numbers of small and medium enterprises can participate in the advancement of at least decarbonization objectives; however, such networks require support from national governments. Besides implications for governance, policy and regulations, the findings of this research could also have implications for corporate behavior in terms of promoting conscious and transparent organizational culture.  相似文献   

Experimental Study of Bearing Capacity of Granular Soils,Reinforced with Innovative Grid-Anchor System   总被引：1，自引：0，他引：1  

Mansour Mosallanezhad  Nader Hataf  Arsalan Ghahramani 《Geotechnical and Geological Engineering》2008,26(3):299-312

The pull-out resistance of reinforcing elements is one of the most significant factors in increasing the bearing capacity of geosynthetic reinforced soils. In this research a new reinforcing element that includes elements (anchors) attached to ordinary geogrid for increasing the pull-out resistance of reinforcements is introduced. Reinforcement therefore consists of geogrid and anchors with cubic elements that attached to the geogrid, named (by the authors) Grid-Anchor. A total of 45 load tests were performed to investigate the bearing capacity of square footing on sand reinforced with this system. The effect of depth of the first reinforcement layer, the vertical spacing, the number and width of reinforcement layers, the distance that anchors are effective, effect of relative density, low strain stiffness and stiffness after local shear were investigated. Laboratory tests showed that when a single layer of reinforcement is used there is an optimum reinforcement embedment depth for which the bearing capacity is the greatest. There also appeared to be an optimum vertical spacing of reinforcing layers for multi-layer reinforced sand. The bearing capacity was also found to increase with increasing number of reinforcement layer, if the reinforcement were placed within a range of effective depth. The effect of soil density also is investigated. Finally the results were compared with the bearing capacity of footings on non-reinforced sand and sand reinforced with ordinary geogrid and the advantages of the Grid-Anchor were highlighted. Test results indicated that the use of Grid-Anchor to reinforce the sand increased the ultimate bearing capacity of shallow square footing by a factor of 3.0 and 1.8 times compared to that for un-reinforced soil and soil reinforced with ordinary geogrid, respectively.  相似文献   

Large-eddy simulation of the flow past a circular cylinder at sub- to super-critical Reynolds numbers     

《Applied Ocean Research》2016

Large-eddy simulation of turbulent flow past a circular cylinder at sub- to super-critical Reynolds numbers is performed using a high-fidelity orthogonal curvilinear grid solver. Verification studies investigate the effects of grid resolution, aspect ratio and convection scheme. Monotonic convergence is achieved in grid convergence studies. Validation studies use all available experimental benchmark data. Although the grids are relatively large and fine enough for sufficiently resolved turbulence near the cylinder, the grid uncertainties are large indicating the need for even finer grids. Large aspect ratio is required for sub-critical Reynolds number cases, whereas small aspect ratio is sufficient for critical and super-critical Reynolds number cases. All the experimental trends were predicted with reasonable accuracy, in consideration the large facility bias, age of most of the data, and differences between experimental and computational setup in particular free stream turbulence and roughness. The largest errors were for under prediction of turbulence separation.  相似文献   

Post-installation pore-pressure changes around spudcan and long-term spudcan behaviour in soft clay     

《Computers and Geotechnics》2014

This paper presents a dual-stage Eulerian–Lagrangian analysis for modelling the entire process of spudcan installation in soft clay, followed by consolidation and working load operation. The analysis consists of three components, namely undrained effective stress Eulerian analysis of spudcan installation, mesh-to-mesh variable mapping and coupled-flow Lagrangian analysis for the post-installation spudcan working behaviour. The results show good agreement with centrifuge model data but also highlight the importance of replicating the hysteretic behaviour of the soil. The findings also show that while a wished-in-place approach was able to model the long-term bearing response of the spudcan, rotational stiffness was over-estimated. This is due to the fact that, while the wished-in-place analysis was able to model the hardening of the soil ahead of the spudcan, it was unable to model the softening of back-flowed soil behind spudcan. The latter influences the spudcan fixity significantly, but not bearing response. Although the analyses were conducted using ABAQUS, they can, in principle, be conducted using other codes.  相似文献   

Effects of base geogrid on geocell-reinforced foundation beds     

《Geomechanics and Geoengineering》2013,8(3):207-216

The effect of a base geogrid layer below the geocell mattress in sand, sand overlying soft clay, and soft clay foundation beds has been studied using a series of laboratory scale load tests. A rigid circular model footing was used to apply static monotonic loading on the foundation beds with and without geocell reinforcement. The model test results show that the provision of an additional layer of planar geogrid at the base of the geocell mattress further increases the performance of the footing in terms of bearing capacity and reduction in surface heave of the foundation bed. It is also observed that the beneficial effect of the base geogrid layer becomes negligible with increasing height of the geocell mattress beyond the influence of the depth of the footing. Strain measurements in the base geogrid layer indicate that it is more effective with the limited heights of the geocell mattress. The earth pressure cells embedded in the subgrade soil provide evidence that when the base geogrid is provided below the geocell mattress, the footing pressure is distributed more uniformly over an extended area.  相似文献   

Probabilistic geotechnical analyses for offshore facilities     

《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2013,7(1):21-42

Society requires increasingly that the hazard and risk associated with engineered constructions be quantified. The current paper presents geotechnical hazard assessment in the context of a risk framework. Concepts of uncertainties, reliability, safety and risk are briefly reviewed. The use of the approach is exemplified for offshore facilities, including piled foundations, jack-up structures, gravity foundations and underwater slopes. The applications demonstrate that probabilistic analyses complement the conventional deterministic safety factor and deformation-based analyses, and contribute to achieving a safe and optimum design. The probabilistic approach adds value to the results with a modest additional effort. The conclusions emphasize the usefulness of a risk assessment, the importance of engineering judgement in the assessment and the need for involving multi-disciplinary competences to achieve reliable estimates of hazard and risk. The profession can only gain by implementing probabilistic-based thinking and risk-based approaches more systematically than before.  相似文献   

Zero-stress,cylindrical wave functions around a circular underground tunnel in a flat,elastic half-space: Incident P-waves     

Chi Hsin Lin  Vincent W. Lee  Maria I. Todorovska  Mihailo D. Trifunac 《Soil Dynamics and Earthquake Engineering》2010

The zero-stress boundary conditions at the surface of the half-space in the presence of surface and sub-surface cavities for in-plane, incident cylindrical P- and SV-waves have always posed challenging problems. The outgoing cylindrical P- and SV-waves can be represented by Hankel functions of radial distance coupled with the sine and cosine functions of angle. Together, at the half-space surface the P- and SV-wave functions are not orthogonal over the semi-infinite radial distance from 0 to infinity. Thus, to simultaneously satisfy the zero in-plane, normal, and shear stresses, an approximation of the geometry is often made. This paper presents an analytical formulation of the boundary-valued problem, where the Hankel wave functions are expressed in integral form, changing the representation from cylindrical to rectangular coordinates, so that the zero-stress boundary conditions at the half-space surface can be applied in a more straightforward way.  相似文献