Sloshing behaviours of rectangular and cylindrical liquid tanks subjected to harmonic and seismic excitations

A numerical and experimental study on the sloshing behaviours of cylindrical and rectangular liquid tanks is addressed. A three‐dimensional boundary element method for space with the second‐order Taylor series expansion in time is established to simulate the sloshing phenomenon and its related physical quantities inside a liquid tank subjected to horizontal harmonic oscillations or recorded earthquake excitations. The small‐scale model experiments are carried out to verify some results of numerical methods in this study. The comparisons between numerical and experimental results show that the numerical method is reliable for both kinds of ground excitations. Finally, the water wave and the base shear force of a rectangular tank due to harmonic excitation are also presented at different frequencies. A huge cylindrical water tank subjected to a recorded earthquake excitation is used for application and discussion. Copyright © 2007 John Wiley & Sons, Ltd.     

Models for Polar Haze Formation in Jupiter's Stratosphere

We present coupled chemical-microphysical models for the formation, growth, and physical properties of the jovian polar haze based on a gas-phase photochemical model for the auroral regions developed by A. S. Wong et al. (2000, Astrophys. J.534, L215-217). In this model, auroral particle precipitation provides an important energy source for enhanced decomposition of methane and production of benzene and polycyclic aromatic hydrocarbons (PAHs). We find that at high altitude, A₄ (pyrene, a hydrocarbon consisting of four fused aromatic rings) should homogeneously nucleate to form tiny primary particles. At lower altitudes, A₃ (phenanthrene) and A₂ (naphthalene) heterogeneously nucleate on the A₄ nuclei. These particles subsequently grow by additional condensation of A₂ on the nucleated particles and by coagulation and eventually sediment out to the troposphere. We run different cases of the aerosol microphysical model for different assumptions regarding the fractal dimension of aggregate particles formed by the coagulation process. If coagulation is assumed to produce spherical particles (of dimensionality 3), then their mean radius at altitudes below the 20-mbar pressure level is computed to be approximately 0.1 μm. If coagulation produces fractal aggregates of dimension 2.1, then their equivalent mean radius below the 20-mbar level is much larger, of order 0.7 μm. Aggregates with fractal dimensions between 2.1 and 3 form with equivalent mean radii between 0.1 and 0.7 μm. In every case, mean particle radius is found to decrease with increasing altitude, as expected for a system approximately in sedimentation-coagulation equilibrium. The predicted range of altitudes where aerosol formation occurs and the mean size to which particles grow are found to be generally consistent with observations. However, our calculations cannot presently account for the large amount of total aerosol loading inferred by M. G. Tomasko et al. (1986, Icarus65, 218-243). We suggest that the primarily neutral chemical pathway to heavy hydrocarbon and PAH formation proposed by Wong et al. (2000) may proceed too slowly to produce a sufficient amount of condensible material. Inclusion of ion and ion-neutral reactions in the chemical scheme could potentially lead to the prediction of higher PAH production rates, higher nucleation rates, and greater aerosol loading, producing better agreement with the observations.     

Laboratory studies on the reactions between Chlorine,Sulfur Dioxide,and Oxygen: Implications for the Venus Stratosphere

The title reaction was studied by photolyzing mixtures of Cl₂ and SO₂ with and without O₂ present in an atmosphere of N₂, using Fourier transform infrared spectrophotometry to monitor reactants and products. In the absence of oxygen, sulfur dioxide is quantitatively converted to sulfuryl chloride. With 10 to 150 Torr O₂ present H₂SO₄ is produced as well as SO₂Cl₂. When a number of speculative reactions inferred from these experiments are added to a published model for Venus stratospheric chemistry, it emerges that SO₂Cl₂ is a key reservoir species for chlorine and that the reaction between Cl and So₂ provides an important cycle for destroying O₂ and converting SO₂ to H₂So₄. The modified model could provide a possible solution to the photochemistry of the Venus stratosphere if the mixing ratio of chlorine on Venus were as high as 8 ppm.     

1985年乌恰7.4级地震形变带

1985年乌恰7.4级地震在克孜勒苏河谷阶地上出现地表形变带,主要由地震陡坎、地震断层、地裂缝与挤压脊等形迹组成。长约15公里,最宽达800米。分布形态为一向东北突出的弧形形变带。逆断层走向近东西,倾向160°—210°,倾角30°左右,最大水平倾向断距约2米。正走滑断层走向340°—350°,倾向北东,倾角80°—88°,最大右旋水平位错为1.55米。走滑逆断层走向为280°—305°。倾向西南,倾角30°左右,最大右旋水平位移1.25米。挤压脊多呈东西向分布,最大缩短距离为0.4米     

Determination of O2(a1 delta g) and O2(b1 sigma+ g) yields in the reaction O + ClO --> Cl + O2: implications for photochemistry in the atmosphere of Venus

A discharge flow apparatus with chemiluminescence detector has been used to study the reaction O + ClO --> Cl + O2, where O2 = O2(a1 delta g) or O2(b1 sigma+ g). The measured quantum yields for producing O2(a1 delta g) and O2(b1 sigma+ g) in the above reaction are less than 2.5 x 10(-2) and equal to (4.4 +/- 1.1) x 10(-4), respectively. The observed O2(a1 delta g) airglow of Venus cannot be explained in the context of standard photochemistry using our experimental results and those reported in recent literature. The possibility of an alternative source of O atoms derived from SO2 photolysis in the mesosphere of Venus is suggested.     

Fractionation of hydrogen and deuterium on Venus due to collisional ejection

The fractionation factor f is important for interpreting the current escape fluxes of H and D on Venus and how the D/H ratio has evolved. The escape flux is currently governed by the two processes of charge exchange and collisional ejection by fast oxygen atoms. Using a best-fit parameterized equation for the O-H scattering angle phase function, more accurate branching ratios for the oxygen ion dissociation and including the effects of the initial energy and momentum of the ions and electrons, as well as for the hydrogen and deuterium gas, we have reanalyzed the collisional ejection process. Our analysis produces improved values for the efficiency of H and D escape as a function of the ionospheric temperature. From our results we propose the reduction of the hydrogen flux for collisional ejection from 8 to 3.5 x 10(6) cm-2 s-1. Assuming that collisions leading to escape occur mostly in the region between 200 and 400 km, the revised D/H fractionation factor due to collisional ejection is 0.47, where previously the process had been considered completely discriminating against deuterium escape (or f approximately 0.) The resulting deuterium flux is 3.1 x 10(4) cm-2 s-1, roughly 6 times the flux due to charge exchange, making collisional ejection the dominant escape mechanism for deuterium on Venus.     

A pseudo‐force iterative method with separate scale factors for dynamic analysis of structures with non‐proportional damping

Dynamic equilibrium equations of structural systems with non‐proportional damping are coupled through the damping terms. Such coupling invalidates application of the classical modal superposition method. In this paper, a mode‐superposition pseudo‐force method is proposed. The coupled equilibrium equations are solved by an iterative process in which the coupling terms are treated as pseudo‐forces. A scale factor for each mode of the system is obtained by optimizing the iteration convergence. Through these uniquely solved scale factors, the modified modal equations not only converge much faster but also yield results with higher accuracy. A proof of the convergence of the iterative process is also presented. Copyright © 2002 John Wiley & Sons, Ltd.     

Isotopic exchange between carbon dioxide and ozone via O(1D) in the stratosphere

We propose a novel mechanism for isotopic exchange between CO2 and O3 via O(1D) + CO2 --> CO3* followed by CO3* --> CO2 + O(3P). A one-dimensional model calculation shows that this mechanism can account for the enrichment in 18O in the stratospheric CO2 observed by Gamo et al. [1989], using the heavy O3 profile observed by Mauersberger [1981]. The implications of this mechanism for other stratospheric species and as a source of isotopically heavy CO2 in the troposphere are briefly discussed.     

The effect of carbon tax on carbon emission abatement and GDP: a case study

Carbon tax has been advocated as an effective economic instrument for the abatement of CO₂ emission by various countries, including China, the world’s biggest carbon emission country. However, carbon emission abatement cannot be done while ignoring the impact on economic growth. A delicate balance needs to be achieved between the two to find an appropriate pathway for sustainable development. This paper applies a multi-objective optimization approach to analyze the impact of levying carbon tax on the energy-intensive sectors of Guangdong province in China under the constraint of emission reduction target. This approach allows us to evaluate carbon emission minimization while maximizing GDP. For policy analysis, we construct five scenarios for evaluation and optimal choice. The results of the analysis show that a lower initial carbon tax rate is not necessarily better, and that a carbon tax is an effective means to reduce CO₂ emissions while maintaining a certain level of GDP growth.     

A case study of internal solitary wave propagation during ASIAEX 2001

During the recent Asian Seas International Acoustics Experiment (ASIAEX), extensive current meter moorings were deployed around the continental shelf-break area in the northeastern South China Sea. Thirteen RADARSAT SAR images were collected during the field test to integrate with the in situ measurements from the moorings, ship-board sensors, and conductivity/temperatire/depth (CTD) casts. Besides providing a synoptic view of the entire region, satellite imagery is very useful for tracking the internal waves, locating surface fronts, and identifying mesoscale features. During ASIAEX in May 2001, many large internal waves were observed at the test area and were the major oceanic features studied for acoustic volume interaction. Based on the internal wave distribution maps compiled from satellite data, the wave crests can be as long as 200 km with an amplitude of 100 m. Environmental parameters have been calculated based on extensive CTD casts data near the ASIAEX area. Nonlinear internal wave models have been applied to integrate and assimilate both synthetic aperture radar (SAR) and mooring data. Using SAR data in deep water as an initial condition, numerical simulations produced the wave evolution on the continental shelf and compared reasonably well with the mooring measurements at the downstream station. The shoaling, turning, and dissipation of large internal waves at the shelf break have been studied and are very important issues for acoustic propagation.