Theoretical investigation of 5D-metal monocarbide

Bond distances, vibrational frequencies, electron affinities, ionization potentials and dissociation energies of the title molecules in neutral, positively and negatively charged ions were studied by use of density functional method. The calculated results were compared with previous theoretical and experimental studies. Ground states for each molecule were assigned. It was found that for some molecules, low-lying state, in which the energy is much close to the ground state, was obtained. In this case, further studies both experimentally and theoretically are necessary in order to find the true global minimum.

Electronic structures of MCO (M = Nb, Ta, Rh, Ir, Pd, Pt) molecules by density functional theory

Equilibrium geometries, vibrational frequencies, and dissociation energies of the transition metal carbonyls MCO (M = Nb, Ta, Rh, Ir, Pd, Pt) were studied by use of diverse density functional methods B3LYP, BLYP, B3P86, B3PW91, BHLYP, BP86, and PBE1PBE. It was found that the ground electronic state is (6)Sigma(+) for NbCO and TaCO, (2)Sigma(+) for RhCO,(2)Delta for IrCO, and (1)Sigma(+) for PdCO and PtCO, in agreement with previous theoretical studies. The calculated properties are highly dependent on the functionals employed, in particular for the dissociation energy. For most of the molecules, the predicted bond distance is in agreement with experiments and previous theoretical results. BHLYP is the worst method in reproducing the experimental results compared with the other density functional methods for the title molecules.

Funneled landscape leads to robustness of cellular networks: MAPK signal transduction

We uncover the underlying potential energy landscape for a cellular network. We find that the potential energy landscape of the mitogen-activated protein-kinase signal transduction network is funneled toward the global minimum. The funneled landscape is quite robust against random perturbations. This naturally explains robustness from a physical point of view. The ratio of slope versus roughness of the landscape becomes a quantitative measure of robustness of the network. Funneled landscape is a realization of the Darwinian principle of natural selection at the cellular network level. It provides an optimal criterion for network connections and design. Our approach is general and can be applied to other cellular networks.

Chemical bonding and electronic structure of 4d-metal monocarbides

Bond distances, vibrational frequencies, dissociation energies, electron affinities, ionization potentials and dipole moments of the title molecules in neutral and charged ions were studied by use of density functional method. Ground states for each molecule were assigned. For neutral and cationic molecules, the bond distance decreases from YC (YC+) to RhC (RhC+), then increases, while for anionic molecules, the bond distance decreases from YC- to RuC-, then increases. Opposite trend was observed for vibrational frequency. The bond ionic character decreases from ZrC to PdC for neutral molecules. The bonding patterns are discussed and compared with the available studies.

Theoretical study on the mechanisms of some elementary reactions catalyzed by modified carbonyl cobalt

All structural geometries of intermediates, transition states and product are, optimized at HF/ LANL2DZ level under the effective core potential approximation. The potential energy profile for some elementary reactions of hydroformylation catalyzed by Co-2(CO)(6)(PH3)(2), consisting of carbonyl insertion, H-2 oxidative addition and aldehyde reductive elimination, are calculated, The transition states are further confirmed by having one and only one imaginary vibrational frequency, The activation energies of carbonyl insertion, H-2 oxidative addition and aldehyde reductive elimination are 54, 02, 134, 02 and 43. 44 kJ/mol, respectively.

Vibrational spectra and structure of zinc phthalocyanine

Semi-empirical molecular orbital calculations using PM3 Hamiltonian were employed to determine qualitative assignments of the vibrational spectrum of zinc phthalocyanine (ZnPc). The assignments are from the potential energy distribution calculations in the normal coordinate analysis and optimized geometry in the PM3 calculations. The structure of the ZnPc molecule is also deduced. (C) 1999 Elsevier Science B.V. All rights reserved.

Recent development of intermediate ion/neutral complexes

The fundamental aspects of ion/neutral complex as an important intermediate of unimolecular fragmentation in mass spectrometry have been summarized in this review, especially for the classified description of its formations, characteristics, reactions, investigation methods, recent achievements and application. Meanwhile, another kind of proton-bound complex, which is a special type of ion/neutral complex, has been also introduced briefly. Among them, a part of authors' work was included.

THEORETICAL-STUDIES ON THE CYCLIZATION PROCESS OF A NEW ORGANOSULFUR REACTION

The cyclization process of a new organosulfur reaction was studied by the MNDO (UHF) method. The first reaction path was assumed to be via the organosulfur radical intermediate, the second via the ionic (cationic and anionic) intermediates. The dehydroxylation process was assumed to occur with the synergistic cyclization. The results obtained indicate that the potential energy barrier of the first reaction path was about 102 kcal mol(-1), and although the formation of the ionic intermediate is comparatively difficult, the potential energy barrier of the second path is comparable to the first. The sequential reaction path via the radical intermediate, i.e. first cyclization, then dehydroxylation, was investigated for comparison. The cyclization reaction was found to be the thermodynamically favored process, while the ensuing dehydroxylation process was found to have a potential energy barrier of about 62 kcal mol(-1).

Mixed-layer water oscillations in tropical Pacific for ENSO cycle

The main modes of interannal variabilities of thermocline and sea surface wind stress in the tropical Pacific and their interactions are investigated, which show the following results. (1) The thermocline anomalies in the tropical Pacific have a zonal dipole pattern with 160 W as its axis and a meridional seesaw pattern with 6-8 degrees N as its transverse axis. The meridional oscillation has a phase lag of about 90 to the zonal oscillation, both oscillations get together to form the El Nino/La Nina cycle, which behaves as a mixed layer water oscillates anticlockwise within the tropical Pacific basin between equator and 12 degrees N. (2) There are two main patterns of wind stress anomalies in the tropical Pacific, of which the first component caused by trade wind anomaly is characterized by the zonal wind stress anomalies and its corresponding divergences field in the equatorial Pacific, and the abnormal cross- equatorial flow wind stress and its corresponding divergence field, which has a sign opposite to that of the equatorial region, in the off-equator of the tropical North Pacific, and the second component represents the wind stress anomalies and corresponding divergences caused by the ITCZ anomaly. (3) The trade winds anomaly plays a decisive role in the strength and phase transition of the ENSO cycle, which results in the sea level tilting, provides an initial potential energy to the mixed layer water oscillation, and causes the opposite thermocline displacement between the west side and east side of the equator and also between the equator and 12 degrees N of the North Pacific basin, therefore determines the amplitude and route for ENSO cycle. The ITCZ anomaly has some effects on the phase transition. (4) The thermal anomaly of the tropical western Pacific causes the wind stress anomaly and extends eastward along the equator accompanied with the mixed layer water oscillation in the equatorial Pacific, which causes the trade winds anomaly and produces the anomalous wind stress and the corresponding divergence in favor to conduce the oscillation, which in turn intensifies the oscillation. The coupled system of ocean-atmosphere interactions and the inertia gravity of the mixed layer water oscillation provide together a phase-switching mechanism and interannual memory for the ENSO cycle. In conclusion, the ENSO cycle essentially is an inertial oscillation of the mixed layer water induced by both the trade winds anomaly and the coupled ocean-atmosphere interaction in the tropical Pacific basin between the equator and 12 degrees N. When the force produced by the coupled ocean-atmosphere interaction is larger than or equal to the resistance caused by the mixed layer water oscillation, the oscillation will be stronger or maintain as it is, while when the force is less than the resistance, the oscillation will be weaker, even break.

基于改进势场法的可变形机器人路径规划研究

采用传统的势场法对机器人进行路径规划时,如果目标位置处在障碍物产生的斥力影响范围内,由于斥力大于引力机器人很难到达目标,为此本文提出了一种改进的势场法。该算法通过机器人向着合势能最小的方向运动完成路径规划。并对目标产生的引力做了进一步的改进,解决了目标不可达问题。同时改进的方法不会增加计算量,保证了算法的实时性。仿真实验证明了机器人能够避开障碍顺利到达目标,验证了改进算法的有效性。

地质导向钻井关键技术及方法

On the basis of analyzing the principle and realization of geo-steering drilling system, the key technologies and methods in it are systematically studied in this paper. In order to recognize lithology, distinguish stratum and track reservoirs, the techniques of MWD and data process about natural gamma, resistivity, inductive density and porosity are researched. The methods for pre-processing and standardizing MWD data and for converting geological data in directional and horizontal drilling are discussed, consequently the methods of data conversion between MD and TVD and those of formation description and adjacent well contrast are proposed. Researching the method of identifying sub-layer yields the techniques of single well explanation, multi-well evaluation and oil reservoir description. Using the extremum and variance clustering analysis realizes logging phase analysis and stratum subdivision and explanation, which provides a theoretical method and lays a technical basis for tracing oil reservoirs and achieving geo-steering drilling. Researching the technique for exploring the reservoir top with a holdup section provides a planning method of wellpath control scheme to trace oil and gas reservoir dynamically, which solves the problem of how to control well trajectory on condition that the layer’s TVD is uncertain. The control scheme and planning method of well path for meeting the demands of target hitting, soft landing and continuous steering respectively provide the technological guarantee to land safely and drill successfully for horizontal, extended-reach and multi-target wells. The integrative design and control technologies are researched based on geology, reservoir and drilling considering reservoir disclosing ratio as a primary index, and the methods for planning and control optimum wellpath under multi-target restriction, thus which lets the target wellpath lie the favorite position in oil reservoir during the process of geo-steering drilling. The BHA (bottomhole assembly) mechanical model is discussed using the finite element method, and the BHA design methods are given on the basis of mechanical analyses according to the shape of well trajectory and the characteristics of BHA’s structure and deformation. The methods for predicting the deflection rate of bent housing motors and designing their assemblies are proposed based on the principle of minimum potential energy, which can clearly show the relation between the BHA’s structure parameters and deflection rate, especially the key factors’ effect to the deflection rate. Moreover, the interaction model between bit and formation is discussed through the process of equivalent formation and equivalent bit considering the formation anisotropy and bit anisotropy on the basis of analyzing the influence factors of well trajectory. Accordingly, the inherence relationship among well trajectory, formation, bit and drilling direction is revealed, which lays the theory basis and technique for predicting and controlling well trajectory.

急倾斜金属矿体开采岩体移动规律与变形趋势预测研究

Rockmass movement due to mining steep metallic ore body is a considerable question in the surface movement and deformation issue caused by underground mining. Research on coal mining induced rockmass movement and its prediction problem have been performed for a long-term, and have achieved great progress at home and abroad. However, the rockmass movement caused by mining steep metal mine is distinctivly different from coal seam mining.. Existing surface movement laws and deformation prediction methods are not applicable to the rockmass movement caused by mining steep metal mine. So far the home and abroad research to this theory is presently at an early stage, and there isn’t mature theory or practical prediction method, which made a great impact on production. In this paper, the research object—Jinchuan nickel mine, which is typical steep metal mine, characterized by complex geological conditions, developed faults, cracked rockmass, high geostress, and prominent engineering stability problems. In addition, backfill mining method is used in the mine, the features of rockmass movement caused by this mining method are also different from other mining methods. In this paper, the laws of rock mass movement, deformation and destroy mechanism, and its prediction were analyzed based on the collection of data, detailed in-sit engineering geology survey, ground movement monitoring by GPS, theoretical analysis and numerical simulation. According to the GPS monitoring of ground surface movement, ground subsidence basin with apparent asymmetry is developing, the influence scope is larger in the upper faulted block than in the lower faulted block, and the center of ground movement is moving along the upper faulted block direction with increasing depth of mining. During the past half and seven years, the largest settlement has amounted to 1287.5mm, and corresponding horizontal displacement has amounted to 664.6mm. On the ground surface, two fissure belts show a fast-growing trend of closure. To sum up, mining steep metal mine with backfill method also exist the same serious problem of rockmass movement hazards. Fault, as a low intensity zone in rockmass, when it located within the region of mining influence, the change of potential energy mainly consumed in fault deformation associated with rockmass structure surface friction, which is the essence of displacement and stress barrier effects characterized by fault rupture zone. when steep fault located in the tensile deformation region incurred by underground excavation, no matter excavation in hangingwall or in footwall of the fault, there will be additional tensile stress on the vertical fault plane and decrease in the shear strength, and always showing characteristics of normal fault slip, which is the main reason of fault escarpment appeared on the ground surface. The No.14 shaft deformation and failure is triggered by fault activation, which showed with sidewall move, rupture, and break down features as the main form of a concentrated expression of fault effects. The size and orientation of principal stress in surrounding rock changed regularly with mining; therefore, roadway deformation and damage at different stages have different characteristics and distribution models. During the process of mining, low-intensity weak structures surface always showed the most obvious reaction, accompany with surface normal stress decrease and shear strength bring down, to some extent, occurred with relative slide and deformation. Meanwhile, the impact of mining is a relatively long process, making the structure surface effect of roadway deformation and damage more prominent than others under the influence of mining. Roadway surrounding rockmass deformation caused by the change of strain energy density field after excavation mainly belongs to elastic deformation, and the correspondented damage mainly belongs to brittle rupture, in this circumstance, surrounding rockmass will not appear large deformation. The large deformation of surrounding rockmass can only be the deformation associated with structure surface friction or the plastic deformation of itself, which mainly caused by the permanent self-weigh volume force，and long-term effect of mining led to the durability of this deformation Good pitting fill effect and supporting effect of backfill, as well as the friction of rockmass structure surface lead to obvious macro-rockmass movement with long-lag characteristics. In addition, the loss of original intensity and new structure surface arisen increased flexibility in rockmass and fill deformation in structure surface, which made the time required for rockmass potential energy translate into deformation work associated with plastic deformation and structure surface friction consumed much, and to a large extent, eliminated the time needed to do those plastic work during repeated mining, all of which are the fundamental reason of rockmass movement aftereffect more significant than before. Mining steep deposits in high tectonic stress area and in gravity stress area have different movement laws and deformation mechanism. The steep deposit, when the vertical size of the mining areas is smaller than the horizontal size of the orebody, no matter mining in gravity stress area or in high tectonic stress area, they have similar features of ground movement with mining horizontal orebody; contrarily, there will appear double settlement centers on the ground surface under the condition of mining in high tectonic stress area, while there will always be a single center under the other condition. Meanwhile the ground movement lever, scale of mining influence area and macro features of ground movement, deformation and fracture are also different from mining in gravity stress area, and the fundamental reason lies in the impact of orientation of the maximum principal stress on rock movement features in in-site rock stress field. When mining thick and steep deposit, the ground surface movement and deformation characteristic curves are significantly different from excavating the horizontal ore bed and thin steep deposit. According to the features of rockmass movement rate, the development process of mining-induced rockmass movement is divided into three stages: raising stage, steadily stage and gradually decay stage. Considering the actual exploitation situation, GPS monitoring results and macro-characteristics of surface movement, the current subsidence pattern of Jinchuan No.2 mine is in the early stage of development. Based on analysis of surface movement rate, surface subsidence rate increase rapidly when mining in double lever at the same time, and reach its peak until the exploitation model ended. When double lever mining translate into single, production decreased, surface subsidence rate suddenly start to reduce and maintain a relatively low value, and the largest subsidence center will slowly move along with the hangingwall ore body direction with increasing depth of mining, at the same time, the scope and extent of subsidence in footwall ore body will begin magnify, and a sub-settlement center will appear on ground surface, accompanied with the development and closure trend of ground fissure, the surrounding rockmass of shaft and roadway will be confronted to more frequent and severe deformation and failure, and which will have a negative impact on the overall stability of No.2 mine mining. On the premise of continuity of rockmass movement, gray system model can be used in ground rockmass movement prediction for good results. Under the condition of backfill mining step by step, the loose effect of compact status of the hard, broken rockmass led to lower energy release rate, although surrounding rockmass has high elastic energy, loose and damage occurred in the horizontal ore body, which made the mining process safety without any large geological hazards. During the period of mining the horizontal ore body to end, in view of its special “residual support role”, there will be no large scale rockmass movement hazards. Since ground surface movement mainly related to the intensity of mining speed and backfill effect, on the premise of constant mining speed, during the period of mining the horizontal ore body to end, the rate of ground surface rockmass movement and deformation won’t have sudden change.

地幔对流理论及其在解释地球物理观测的应用

With the improving of mantle convection theory, the developing of computing method and increasing of the measurement data, we can numerically simulate more clearly about the effects on some geophysical observed phenomenons such as the global heat flow and global lithospheric stress field in the Earth's surface caused by mantle convection, which is the primary mechanism for the transport of heat from the Earth's deep interior to its surface and the underlying force mechanism of dynamics in the Earth.Chapter 1 reviews the historical background and present research state of mantle convection theory.In Chapter 2, the basic conception of thermal convection and the basic theory about mantle flow.The effects on generation and distribution of global lithospheric stres s field induced by mantle flow are the subject of Chapter 3. Mantle convection causes normal stress and tangential stresses at the bottom of the lithosphere, and then the sublithospheric stress field induces the lithospheric deformation as sixrface force and results in the stress field within the lithosphere. The simulation shows that the agreement between predictions and observations is good in most regions. Most of subduction zones and continental collisions are under compressive. While ocean ridges, such as the east Pacific ridge, the Atlantic ridge and the east African rift valley, are under tensile. And most of the hotspots preferentially occur in regions where calculated stress is tensile. The calculated directions of the most compressive principal horizontal stress are largely in accord with that of the observation except for some regions such as the NW-Pacifie subduction zone and Qinghai-Tibet Plateau, in which the directions of the most compressive principal horizontal stress are different. It shows that the mantel flow plays an important role in causing or affecting the large-scale stress field within the lithosphere.The global heat flow simulation based on a kinematic model of mantle convection is given in Chapter 4. Mantle convection velocities are calculated based on the internal loading theory at first, the velocity field is used as the input to solve the thermal problem. Results show that calculated depth derivatives of the near surface temperature are closely correlated to the observed surface heat flow pattern. Higher heat flow values around midocean ridge systems can be reproduced very well. The predicted average temperature as a function of function of depth reveals that there are two thermal boundary layers, one is close to the surface and another is close to the core-mantle boundary, the rest of the mantle is nearly isothermal. Although, in most of the mantle, advection dominates the heat transfer, the conductive heat transfer is still locally important in the boundary layers and plays an important role for the surface heat flow pattern. The existence of surface plates is responsible for the long wavelength surface heat flow pattern.In Chapter 5, the effects on present-day crustal movement in the China Mainland resulted from the mantle convection are introduced. Using a dynamic method, we present a quantitative model for the present-day crustal movement in China. We consider not only the effect of the India-Eurasia collision, the gravitational potential energy difference of the Tibet Plateau, but also the contribution of the shear traction on the bottom of the lithosphere induced by the global mantle convection. The comparison between our results and the velocity field obtained from the GPS observation shows that our model satisfactorily reproduces the general picture of crustal deformation in China. Numerical modeling results reveal that the stress field on the base of the lithosphere induced by the mantle flow is probably a considerable factor that causes the movement and deformation of the lithosphere in continental China with its eflfcet focuing on the Eastern China A numerical research on the small-scale convection with variable viscosity in the upper mantle is introduced in Chapter 6. Based on a two-dimensional model, small-scale convection in the mantle-lithosphere system with variable viscosity is researched by using of finite element method. Variation of viscosity in exponential form with temperature is considered in this paper The results show that if viscosity is strongly temperature-dependent, the upper part of the system does not take a share in the convection and a stagnant lid, which is identified as lithosphere, is formed on the top of system because of low temperature and high viscosity. The calculated surface heat flow, topography and gravity anomaly are associated well with the convection pattern, namely, the regions with high heat flow and uplift correspond to the upwelling flow, and vice versa.In Chapter 7, we give a brief of future research subject: The inversion of lateral density heterogeneity in the mantle by minimizing the viscous dissipation.

Ab initio configuration-interaction study of the ground and low-lying electronic states of NiI

For the first time, we have studied the potential-energy curves, spectroscopic terms, vibrational levels, and the spectroscopic constants of the ground and low-lying excited states of NiI by employing the complete active space self-consistent-field method with relativistic effective core potentials followed by multireference configuration-interaction calculations. We have identified six low-lying electronic states of NiI with doublet spin multiplicities, including three states of Delta symmetry and three states of Pi symmetry of the molecule within 15 000 cm(-1). The lowest (2)Delta state is identified as the ground state of NiI, and the lowest (2)Pi state is found at 2174.56 cm(-1) above it. These results fully support the previous conclusion of the observed spectra although our computational energy separation of the two states is obviously larger than that of the experimental values. The present calculations show that the low-lying excited states [13.9] (2)Pi and [14.6] (2)Delta are 3 (2)Pi and 3 (2)Delta electronic states of NiI, respectively. Our computed spectroscopic terms, vibrational levels, and spectroscopic constants for them are in good agreement with the experimental data available at present. In the present work we have not only suggested assignments for the observed states but also computed more electronic states that are yet to be observed experimentally. (c) 2005 American Institute of Physics.

Binding Energy and Spin-Orbit Splitting of a Hydrogenic Donor Impurity in AlGaN/GaN Triangle-Shaped Potential Quantum Well

In the framework of effective-mass envelope function theory, including the effect of Rashba spin-orbit coupling, the binding energy E-b and spin-orbit split energy Gamma of the ground state of a hydrogenic donor impurity in AlGaN/GaN triangle-shaped potential heterointerface are calculated. We find that with the electric field of the heterojunction increasing, (1) the effective width of quantum well (W) over bar decreases and (2) the binding energy increases monotonously, and in the mean time, (3) the spin-orbit split energy Gamma decreases drastically. (4) The maximum of Gamma is 1.22 meV when the electric field of heterointerface is 1 MV/cm.