Coupled surface and ground water models for investigating hydrological processes     

Ray‐Shyan Wu  Dong‐Sin Shih  Ming‐Hsu Li  Chia‐Ching Niu 《水文研究》2008,22(8):1216-1229

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Evaluating the stress intensity factors of anisotropic bimaterials using boundary element method     

Chao‐Shi Chen  Chien‐Chung Ke  Chia‐Huei Tu 《国际地质力学数值与分析法杂志》2008,32(11):1341-1364

This paper presents a boundary element method (BEM) procedure for a linear elastic fracture mechanics analysis in two‐dimensional anisotropic bimaterials. In this formulation, a displacement integral equation is only collocated on the uncracked boundary, and a traction integral equation is only collocated on one side of the crack surface. A fundamental solution (Green's function) for anisotropic bimaterials is also derived and implemented into the boundary integral formulation so that except for the interfacial crack part, the discretization along the interface can be avoided. A special crack‐tip element is introduced to capture the exact crack‐tip behavior. A computer program using FORTRAN has been developed to effectively calculate the stress intensity factors of an anisotropic bimaterial. This BEM program has been verified to have a good accuracy with previous studies. In addition, a central cracked bimaterial Brazilian specimen constituting cement and gypsum is prepared to conduct the Brazilian test under diametral loading. The result shows that the numerical analysis can predict relatively well the direction of crack initiation and the path of crack propagation. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

On the mass-radius relation in close binary systems     

T. T. Chia 《Astrophysics and Space Science》1977,51(1):33-38

In a close binary system with circular orbits in which mass transfer occurs when material from one star fills up and possibly spills over its Roche lobe, the usual mass-radius relation cannot be used as it would lead to unreasonable results in some situations.  相似文献   

Changes in gross moist stability in the tropics under global warming     

Chia Chou  Tzu-Chin Wu  Pei-Hua Tan 《Climate Dynamics》2013,41(9-10):2481-2496

Gross moist stability, an effective static stability, in the tropics is examined in observations and model simulations. Under convective quasi-equilibrium closure, gross moist stability, a vertical integration of the vertical moist static energy gradient weighted by pressure velocity, is derived based on an approximately moist adiabatic process associated with deep convection. In climatology, gross moist stability is generally similar to the spatial distribution of mean precipitation. In global warming simulations, gross moist stability tends to increase in the tropics. It implies a more stable atmosphere, which is consistent with the weakening of tropical circulation found in climate models. Main effects, which induce the changes in gross moist stability, include the low-level moisture effect, the maximum level of convection (MLC) effect, i.e., the depth of deep convection, and the dry static energy effect associated with stratification of temperature, with the first two also found in climatology. Because of the strong cancellation between the effects of low-level moisture and dry static energy due to the moist adiabatic process of deep convection, the effect of MLC, which has been overlooked in measuring atmospheric stability, is crucial in determining the sign of changes in gross moist stability. Gross moist stability is a better index to represent changes in atmospheric stability in the tropics under global warming, compared to both dry and moist static stability.  相似文献   

The activity of convectively coupled equatorial waves in CMIP3 global climate models     

Ping Huang  Chia Chou  Ronghui Huang 《Theoretical and Applied Climatology》2013,112(3-4):697-711

This study evaluates the convectively coupled equatorial waves in ten coupled general circulation models (GCMs) in the twentieth century experiment from the Coupled Model Intercomparison Project phase 3 of the World Climate Research Programme. The antisymmetric bands in all GCMs are weaker than in observations, and the mixed Rossby-gravity (MRG) wave seems to be a mixture of the equatorial Rossby (ER) and tropical depression-type (TD-type) waves rather than a mixture of the ER and inertiogravity waves found in observations. The simulated TD-type wave is more organized than in observations with a quasilinear wavenumber–frequency relationship. In most GCMs, the two observed activity centers of the MRG and TD-type waves over the southern Indian Ocean and the southwestern Pacific cannot be separated; only one wave activity center is found over the Maritime Continent. The observed northwestward propagation of the TD-type wave over the western North Pacific is also not well simulated in the GCMs. The simulated active season of the MRG and TD-type waves over the northern hemisphere during the boreal summer and fall is much shorter than in observations. The models from CCSR utilizing the Pan and Randall scheme with the convection suppression simulate the realistic Kelvin wave activity with the maximum activity near the equator, while the wave activities filtered for the Kelvin wave in the other GCMs are similar to the extratropical Rossby wave with the maximum activity at higher latitudes. Likewise, only these two models produce a realistic seasonal cycle of the Kelvin wave activity.  相似文献   

THE STRATEGIC STRAIT WITH SPECIAL REFERENCE TO THE MALACCA STRAITS1     

Allan Chia  Lee Yong Leng 《Singapore journal of tropical geography》1987,8(2):97-113

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Equivalence of some integrals of the radiation theory     

T. T. Chia 《Astrophysics and Space Science》1977,46(1):239-246

A definite integral which occurs in radiation theory is shown to be equal in value to another definite integral by evaluating the flux from a spherically symmetrical radiating sphere in two ways. As a corollary, an alternate proof of the invariance of the specific intensity of a ray in empty space along its path is presented.Furthermore, the equality of these two indefinite integrals leads to the conversion of members of a class of indefinite and definite integrals involving arbitrary functions of angle into other integrals. These transformations facilitate the calculation of some of these integrals which arise not only in the theory of radiation, but in other physical situations with spherical or axial symmetry — especially those in which inverse-square laws are involved.  相似文献   

Establishing absorbed energy spectra—an attenuation approach     

Chung‐Che Chou  Chia‐Ming Uang 《地震工程与结构动力学》2000,29(10):1441-1455

For energy‐based seismic design, energy demand in the form of absorbed energy spectra was established by an attenuation relationship. The absorbed energy is proposed for evaluating the energy demand in an inelastic system because the absorbed energy is directly related to the pseudo‐velocity in the elastic case. Based on a total of 273 ground motion records from 15 significant earthquakes in California, an attenuation relationship of the absorbed energy was established from a two‐stage non‐linear regression analysis. This relationship was established for a given earthquake magnitude, source‐to‐site distance, site class, and ductility factor. A similar expression for the normalized absorbed energy was also developed. This study showed that the absorbed energy for near‐field ground motions can be significantly larger than that predicted by the attenuation relationship for normal ground motions. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

Analysis of Stock Market Development and CO2 Emissions on OECD Countries via an Empirical Model     

Zhigang Li  Wei‐Ting Chen  I‐Chia Chang  Joe‐Ming Lee 《洁净——土壤、空气、水》2020,48(4)

Accompanying economic growth, CO₂ emissions have polluted the natural environment worldwide. This study highlights the special problems with stock market development and CO₂ emissions in 25 Organization for Economic Cooperation and Development (OECD) countries during 1971–2007 to trace the trend of CO₂ emissions while countries grow their economies. A panel‐data model is applied to analyze the relationships between stock market (SM) development, energy consumption, gross domestic product (GDP), and CO₂ emissions in 25 OECD countries. Low‐GDP countries show different results from high‐GDP countries in the trends of SM development and CO₂ emissions, and dynamic effects occur in SM development and CO₂ emissions under various GDP conditions. There is a negative relationship between SM development and CO₂ emissions if countries enjoy high economic growth, which means that these countries avoid CO₂ emissions through SM development. However, a positive relationship is found between SM development and CO₂ emissions if countries experience low economic growth, which means that SM development does not show the boycott‐effect relationship with CO₂ emissions when countries experience low levels of economic development. This study shows a correlation between SM development and CO₂ emissions among OECD countries.  相似文献   

Graphical methods of river profile analysis to unravel drainage area change,uplift and erodibility contrasts in the Central Range of Taiwan          下载免费PDF全文

Chia‐Yu Chen  Sean D. Willett 《地球表面变化过程与地形》2016,41(15):2223-2238

To reveal river channel steepness patterns and variance in settings with significant variation in rock uplift rate, rock erodibility and moving water divides, we present a series of graphical methods to interpret channel profiles. To complement Cartesian χ plots, longitudinal profiles and mapping methods, we introduce a new method based on a radial coordinate system. We map each basin onto polar coordinates in which the radial dimension is χ and the azimuthal coordinate, ?, is calculated with an increment (Δ?) scaled to the distance to neighboring channel heads. The elevation is contoured on this mapping. Average channel steepness is estimated by fitting a conical surface to the elevation. The graph simplifies the comparison of χ and elevation between channels that share a divide, and helps identify spatial changes in drainage area and patterns of erodibility. We apply this approach to derive the uplift pattern in the eastern and southern Central Range of Taiwan, where the high tectonic convergence and uplift rates combined with sub‐tropical climate and frequent typhoons results in high exhumation rate, and well‐developed, detachment‐limited river networks. Additionally, the tectonic activity leads to drainage basin reorganization. We identify examples of divide migration, discrete river capture as well as anomalous steepness that we attribute to local variability in rock erodibility. Estimated basin‐average steepness values show the highest and a near constant value from Hsinwulu basin to Liwu basin in the center of the Island. To the north and south of this region, the values gradually decrease. These estimates show good correlation with the topography of the Central Range and erosion rates derived from in situ ¹⁰Be concentrations in river‐borne quartz. We conclude that the basin steepness reflects systematic differences in rock uplift rate and erosion rate. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献