扩散波勘探方法基础及其在石油油气藏开发中的应用研究

As we know, the essence of exploration is objective body determined by getting the information. Such as seismic、electrical and electromagnetic prospecting, they are the common methods of the exploration. Therefore, They have a complete set of theory now. In fact, the effective information can also be got by the diffusion way, it is called diffusion prospecting. The diffusion way prospecting is necessary and important. The way of diffusion prospecting is studied in the paper and main works include below: (1) On the basis of studying basic law of the diffusion, the paper gives the idea of diffusion wave and the formulas of computing diffusion wave function. (2) The paper studies the way of the diffusion prospecting and the methods of data processing. At the same time, it also expounds the characteristics and the applied foreground of the diffusion prospecting. (3) The paper gives the tomography idea and the basic method of diffusion CT. Meanwhile, it also expounds the foreground that the diffusion CT is applied in oil development prospecting. (4) As the inversion of the diffusion equation is a part of the diffusion prospecting way, the methods of diffusion equation inversion are studied and the two formulas are deduced --Laplace transform and polynomial fitting inversion formulas. As the other important result of diffusion equation inversion, the inversion can offer a new analysis method for well Testing in oil development. In order to show a set of methods in the paper feasible, forward、inversion and CT numerical simulation are done in the paper.

Photodissociation of 1-bromo-2-chloroethane at 266 nm

The photodissociation of CH2BrCH2Cl at 266 nm has been investigated on the universal crossed molecular beam machine. The primary dissociation step leads exclusively to the formation of CH2CH2Cl radicals and Br atoms in the electronic ground state as well as in the spin-orbit excited state, with a branching ratio 2 +/- 1:8 +/- 1. Photofragment total c.m. translational energy distribution P(E-t) has been obtained and about 64% of the available energy is partitioned into translational energy for Br channel and about 28.5% of the available energy is partitioned into translational energy for Br* channel. The anisotropy parameters are determined to be beta(Br*) = 0.8 +/- 0.2 and beta(Br) = -0.6 +/- 0.2, respectively. Some CH2CH2Cl radicals with large internal excitation (corresponding to formation of ground state Br channel) may undergo secondary dissociation to form CH2CH2 +/- Cl. The experimental results are discussed in terms of a model that involves the initial excitation of two repulsive electronic states: one from an parallel transition to the (3)Q(0) state, and the other from a perpendicular transition to the (3)Q(1), (1)Q states. (C) 1999 Elsevier Science B.V. All rights reserved.

Photodissociation of bromobenzene at 266 nm

The photodissociation of C6H5Br at 266 nm has been investigated on the universal crossed molecular beam machine, and time-of-flight spectra as well as the angular distribution of Br atom have been measured. Photofragment translational energy distribution P(E-t) reveals that about 47% of the available energy is partitioned into translational energy. The anisotropy parameter beta at this wavelength is -0.7+/-0.2. From P(E-t) and beta, we deduce that C6H5Br photodissociation is a fast process and the transition dipole moment is almost perpendicular to the C-Br bond. Ab initio calculations have been performed, and the calculated results show that the geometry of the first excited state of bromobenzene has changed apparently compared with that of the ground state. Two kinds of possible fast dissociation mechanism have also been proposed. (C) 1999 American Institute of Physics. [S0021-9606(99)01206-4].

Photodissociation of o-dichlorobenzene at 266 nm

The photodissociation o-dichlorobenzene at 266 nm has been investigated using the universal crossed molecular beam technique. Photofragment translational energy distribution P(E-t) and angular distribution of photofragments have been obtained and it is estimated that 23% of the available energy is assigned to translational energy. The anisotropy parameter is determined to be 0.4. From P(E-t) and beta we deduce that o-C6H4Cl2 photodissociation is a slow process. Ab initio calculation has been performed and it shows that the parent molecule has a larger geometry deformation in its excited states comparing with that of the ground state. The possible dissociation mechanism has also been proposed. (C) 1999 Elsevier Science B.V. All rights reserved.

A new interatomic potential for nanoscale silica

Flikkema, Edwin; Bromley, S.T., (2003) 'A new interatomic potential for nanoscale silica', Chemical Physics Letters 378(5-6) pp.622-629 RAE2008

Mieszanie stanów magnetycznych w skończonych układach spinowych opisywanych modelem Heisenberga

Wydział Fizyki: Zakład Fizyki Komputerowej

Possible Exotic Phases in the One-Dimensional Extended Hubbard Model

We investigate numerically the ground state phase diagram of the one-dimensional extended Hubbard model, including an on--site interaction U and a nearest--neighbor interaction V. We focus on the ground state phases of the model in the V >> U region, where previous studies have suggested the possibility of dominant superconducting pairing fluctuations before the system phase separates at a critical value V=V_PS. Using quantum Monte Carlo methods on lattices much larger than in previous Lanczos diagonalization studies, we determine the boundary of phase separation, the Luttinger Liquid correlation exponent K_rho, and other correlation functions in this region. We find that phase separation occurs for V significantly smaller than previously reported. In addition, for negative U, we find that a uniform state re-enters from phase separation as the electron density is increased towards half filling. For V < V_PS, our results show that superconducting fluctuations are not dominant. The system behaves asymptotically as a Luttinger Liquid with K_rho < 1, but we also find strong low-energy (but gapped) charge-density fluctuations at a momentum not expected for a standard Luttinger Liquid.

Spatial and energetic mode dynamics of cold atomic systems

In this thesis we relate the formal description of various cold atomic systems in the energy eigenbasis, to the observable spatial mode dynamics. Herein the `spatial mode dynamics' refers to the direction of photon emission following the spontaneous emission of an excited fermion in the presence of a same species and spin ideal anisotropic Fermi sea in its internal ground state. Due to the Pauli principle, the presence of the ground state Fermi sea renders the phase space, anisotropic and only partially accessible, thereby a ecting the direction of photon emission following spontaneous emission. The spatial and energetic mode dynamics also refers to the quantum `tunneling' interaction between localised spatial modes, synonymous with double well type potentials. Here we relate the dynamics of the wavefunction in both the energetic and spatial representations. Using this approach we approximate the relationship between the spatial and energetic representations of a wavefunction spanning three spatial and energetic modes. This is extended to a process known as Spatial Adiabatic Passage, which is a technique to transport matter waves between localised spatial modes. This approach allows us to interpret the transport of matter waves as a signature of a geometric phase acquired by the one of the internal energy eigenstates of the system during the cyclical evolution. We further show that this geometric phase may be used to create spatial mode qubit and qutrit states.

Quantum behavior in mesoscopic systems

In this thesis I present the work done during my PhD. The Thesis is divided into two parts; in the first one I present the study of mesoscopic quantum systems whereas in the second one I address the problem of the definition of Markov regime for quantum system dynamics. The first work presented is the study of vortex patterns in (quasi) two dimensional rotating Bose Einstein condensates (BECs). I consider the case of an anisotropy trapping potential and I shall show that the ground state of the system hosts vortex patterns that are unstable. In a second work I designed an experimental scheme to transfer entanglement from two entangled photons to two BECs. This work is meant to propose a feasible experimental set up to bring entanglement from microscopic to macroscopic systems for both the study of fundamental questions (quantum to classical transition) and technological applications. In the last work of the first part another experimental scheme is presented in order to detect coherences of a mechanical oscillator which is assumed to have been previously cooled down to the quantum regime. In this regime in fact the system can rapidly undergo decoherence so that new techniques have to be employed in order to detect and manipulate their states. In the scheme I propose a micro-mechanical oscillator is coupled to a BEC and the detection is performed by monitoring the BEC with a negligible back-action on the cantilever. In the second part of the thesis I give a definition of Markov regime for open quantum dynamics. The importance of such definition comes from both the mathematical description of the system dynamics and from the understanding of the role played by the environment in the evolution of an open system. In the Markov regime the mathematical description can be simplified and the role of the environment is a passive one.

Experimental study of quantum dot and dash lasers

Quantum dashes are elongated quantum dots. Polarized edge-photovoltage and spontaneous emission spectroscopy are used to study the anisotropy of optical properties in 1.5μm InGaAsP and AlGaInAs-based quantum dash lasers. Strain, which causes TM-polarized transitions to be suppressed at the band edge, coupled with carrier confinement and dash shape leads to an enhancement of the optical properties for light polarized along the dash long axis, in excellent agreement with theoretical results. An analysis of the integrated facet and spontaneous emission rate with total current and temperature reveals that, in both undoped and p-doped InGaAsP-based quantum dash lasers at room temperature, the threshold current and its temperature dependence remain dominated by Auger recombination. We also identify two processes which can limit the output power and propose that the effects of the dopant in p-doped InGaAsP-based lasers dominate at low temperature but decrease with increasing temperature. A high threshold current density in undoped AlGaInAs-based quantum dash laser samples studied, which degrade rapidly at low temperature, is not due to intrinsic carrier recombination processes. 1.3μm GaAs-based quantum dots lasers have been widely studied, but there remains issues as to the nature of the electronic structure. Polarized edge-photovoltage spectroscopy is used to investigate the energy distribution and nature of the energy states in InAs/GaAs quantum dot material. A non-negligible TM-polarized transition, which is often neglected in calculations and analyses, is measured close to the main TE-polarized ground state transition. Theory is in very good agreement with the experimental results and indicates that the measured low-energy TM-polarized transition is due to the strong spatial overlap between the ground state electron and the light-hole component of a low-lying excited hole state. Further calculations suggest that the TM-polarized transition reduces at the band edge as the quantum dot aspect ratio decreases.

Platinum nuclei: Concealed configuration mixing and shape coexistence

The role of configuration mixing in the Pt region is investigated. For this chain of isotopes, the nature of the ground state changes smoothly, being spherical around mass A~174 and A~192 and deformed around the midshell N=104 region. This has a dramatic effect on the systematics of the energy spectra as compared to the systematics in the Pb and Hg nuclei. Interacting boson model with configuration mixing calculations are presented for gyromagnetic factors, α-decay hindrance factors, and isotope shifts. The necessity of incorporating intruder configurations to obtain an accurate description of the latter properties becomes evident. © 2011 American Physical Society.

Structural manifestation of the delocalization error of density functional approximations: C(4N+2) rings and C(20) bowl, cage, and ring isomers.

The ground state structure of C(4N+2) rings is believed to exhibit a geometric transition from angle alternation (N < or = 2) to bond alternation (N > 2). All previous density functional theory (DFT) studies on these molecules have failed to reproduce this behavior by predicting either that the transition occurs at too large a ring size, or that the transition leads to a higher symmetry cumulene. Employing the recently proposed perspective of delocalization error within DFT we rationalize this failure of common density functional approximations (DFAs) and present calculations with the rCAM-B3LYP exchange-correlation functional that show an angle-to-bond-alternation transition between C(10) and C(14). The behavior exemplified here manifests itself more generally as the well known tendency of DFAs to bias toward delocalized electron distributions as favored by Huckel aromaticity, of which the C(4N+2) rings provide a quintessential example. Additional examples are the relative energies of the C(20) bowl, cage, and ring isomers; we show that the results from functionals with minimal delocalization error are in good agreement with CCSD(T) results, in contrast to other commonly used DFAs. An unbiased DFT treatment of electron delocalization is a key for reliable prediction of relative stability and hence the structures of complex molecules where many structure stabilization mechanisms exist.

Probing near-infrared photorelaxation pathways in eumelanins and pheomelanins.

Ultraviolet-visible spectroscopy readily discerns the two types of melanin pigments (eumelanin and pheomelanin), although fundamental details regarding the optical properties and pigment heterogeneity are more difficult to disentangle via analysis of the broad featureless absorption spectrum alone. We employed nonlinear transient absorption spectroscopy to study different melanin pigments at near-infrared wavelengths. Excited-state absorption, ground-state depletion, and stimulated emission signal contributions were distinguished for natural and synthetic eumelanins and pheomelanins. A starker contrast among the pigments is observed in the nonlinear excitation regime because they all exhibit distinct transient absorptive amplitudes, phase shifts, and nonexponential population dynamics spanning the femtosecond-nanosecond range. In this manner, different pigments within the pheomelanin subclass were distinguished in synthetic and human hair samples. These results highlight the potential of nonlinear spectroscopies to deliver an in situ analysis of natural melanins in tissue that are otherwise difficult to extract and purify.

Reformulating time-dependent density functional theory with non-orthogonal localized molecular orbitals.

Time-dependent density functional theory (TDDFT) has broad application in the study of electronic response, excitation and transport. To extend such application to large and complex systems, we develop a reformulation of TDDFT equations in terms of non-orthogonal localized molecular orbitals (NOLMOs). NOLMO is the most localized representation of electronic degrees of freedom and has been used in ground state calculations. In atomic orbital (AO) representation, the sparsity of NOLMO is transferred to the coefficient matrix of molecular orbitals (MOs). Its novel use in TDDFT here leads to a very simple form of time propagation equations which can be solved with linear-scaling effort. We have tested the method for several long-chain saturated and conjugated molecular systems within the self-consistent charge density-functional tight-binding method (SCC-DFTB) and demonstrated its accuracy. This opens up pathways for TDDFT applications to large bio- and nano-systems.

Comparison of the experimental, semi-experimental and ab initio equilibrium structures of acetylene: Influence of relativisitic effects and of the diagonal Born-Oppenheimer corrections

The equilibrium structure of acetylene (also named ethyne) has been reinvestigated to resolve the small discrepancies noted between different determinations. The size of the system as well as the large amount of available experimental data provides the quite unique opportunity to check the magnitude and relevance of various contributions to equilibrium structure as well as to verify the accuracy of experimental results. With respect to pure theoretical investigation, quantum-chemical calculations at the coupled-cluster level have been employed together with extrapolation to the basis set limit, consideration of higher excitations in the cluster operator, inclusion of core correlation effects as well as relativistic and diagonal Born-Oppenheimer corrections. In particular, it is found that the extrapolation to the complete basis set limit, the inclusion of higher excitations in the electronic-correlation treatment and the relativistic corrections are of the same order of magnitude. It also appears that a basis set as large as a core-valence quintuple-zeta set is required for accurately accounting for the inner-shell correlation contribution. From a pure experimental point of view, the equilibrium structure has been determined using very accurate rotational constants recently obtained by a global analysis (that is to say that all non-negligible interactions are explicitely included in the Hamiltonian matrix) of rovibrational spectra. Finally, a semi-experimental equilibrium structure (where the equilibrium rotational constants are obtained from the experimental ground state rotational constants and computed rovibrational corrections) has been obtained from the available experimental ground-state rotational constants for ten isotopic species corrected for computed vibrational corrections. Such a determination led to the revision of the ground-state rotational constants of two isotopologues, thus showing that structural determination is a good method to identify errors in experimental rotational constants. The three structures are found in a very good agreement, and our recommended values are rCC 120.2958(7) pm and rCH 106.164(1) pm. © 2011 American Institute of Physics.