Mean-field transport of a Bose-Einstein condensate

The expansion of an initially confined Bose-Einstein condensate into either free space or a tilted optical lattice is investigated in a mean-field approach. The effect of the interactions is to enhance or suppress the transport depending on the sign and strength of the interactions. These effects are discusses in detail in view of recent experiments probing non-equilibrium transport of ultracold quantum gases

The effects of state's construction procurement policy implementation on the outcome of local construction projects : the Libyan case

The successful execution of public construction projects and keeping them within estimated cost and prescribed schedules, quality and satisfying policy goals depend on a methodology that requires sound engineering and managerial judgment. This problem is more evident in the public traditional or adversarial type of contracts in which the contract is awarded to the lowest bidder. Construction procurement policy of public projects has been utilised by many countries as an important tool for achieving economic, social, political and other objectives in developing all aspects of change in the construction industry. Although the construction industry in Libya has suffered ever since the UN sanctions, recent events in the region coupled with the restructuring of the economy, lifting the sanctions and re-establishing new relations with the developed world and global free trade organisations, and attracting foreign investments are expected to yield an unprecedented growth in the construction activities. The Libyan infrastructure is in desperate need for development projects in many areas, especially in the fields of water collection and distribution, tourism and housing. As a result, an unprecedented number of projects are currently under planning and contract awarding stages, which poses as a potentially effective opportunity to drive for change in the construction industry and beyond. This research is an insight of the issue of how construction procurement policies are made and how they affect the outcome of a local public construction project in the current Libyan setting. This was achieved by dividing the first theoretical part in to three pillars or elements of research concerned with, Public policy in the context of construction procurement; Public Sector construction procurement and Public Sector Projects Outcome to build a solid platform of a conceptual knowledge before embarking on a case study investigation to give the required realistic background to the scientific research. Three case studies were selected based upon criteria drawn from the literature review. An intra and cross case study analysis were carried out based mainly on projects' a review and analysis of projects' documentation, but supported by questionnaires and an interviews for each project case study, which enabled a process of contrast comparison, replication and interpretation of findings. It was found that public construction procurement policy in the Libyan local context lacked clarity in defining policy goals. Moreover, construction procurement is perceived as a contract strategy or an arrangement, where by emphasis on the technical aspect was far greater than emphasis on other related policy as a drive-for-change aspects. The policy of restricting the form of public projects contracts made for hard to local public clients to embrace other procurement systems, which might have been more beneficial to the outcome of projects in terms of satisfying policy goals. It appeared that State bodies are more concerned with the administrative side of these projects. Technical and project managerial aspects are usually left for their consultants, either public or private. This caused a serious detachment of control and therefore difficulties and shortcomings in using the construction procurement of local public projects as a policy tool. The main findings of the analysis were based on taxonomy of documentary data collected in the case studies, which assisted in generating conclusions linking back to the theory of the three research elements mentioned above. Finally recommendations along the lines of enhancing transparency, the communication process, the need for a comprehensive State guidelines and the need for vocational education and training to participating State bodies were presented as an attempt to inform and possibly assist academics and Libyan policy makers to achieve positive and fruitful goals in local construction projects through good construction procurement policy making and implementation.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

The effects of state's construction procurement policy implementation on the outcome of local construction projects : the Libyan case

The successful execution of public construction projects and keeping them within estimated cost and prescribed schedules, quality and satisfying policy goals depend on a methodology that requires sound engineering and managerial judgment. This problem is more evident in the public traditional or adversarial type of contracts in which the contract is awarded to the lowest bidder. Construction procurement policy of public projects has been utilised by many countries as an important tool for achieving economic, social, political and other objectives in developing all aspects of change in the construction industry. Although the construction industry in Libya has suffered ever since the UN sanctions, recent events in the region coupled with the restructuring of the economy, lifting the sanctions and re-establishing new relations with the developed world and global free trade organisations, and attracting foreign investments are expected to yield an unprecedented growth in the construction activities. The Libyan infrastructure is in desperate need for development projects in many areas, especially in the fields of water collection and distribution, tourism and housing. As a result, an unprecedented number of projects are currently under planning and contract awarding stages, which poses as a potentially effective opportunity to drive for change in the construction industry and beyond. This research is an insight of the issue of how construction procurement policies are made and how they affect the outcome of a local public construction project in the current Libyan setting. This was achieved by dividing the first theoretical part in to three pillars or elements of research concerned with, Public policy in the context of construction procurement; Public Sector construction procurement and Public Sector Projects Outcome to build a solid platform of a conceptual knowledge before embarking on a case study investigation to give the required realistic background to the scientific research. Three case studies were selected based upon criteria drawn from the literature review. An intra and cross case study analysis were carried out based mainly on projects' a review and analysis of projects' documentation, but supported by questionnaires and an interviews for each project case study, which enabled a process of contrast comparison, replication and interpretation of findings. It was found that public construction procurement policy in the Libyan local context lacked clarity in defining policy goals. Moreover, construction procurement is perceived as a contract strategy or an arrangement, where by emphasis on the technical aspect was far greater than emphasis on other related policy as a drive-for-change aspects. The policy of restricting the form of public projects contracts made for hard to local public clients to embrace other procurement systems, which might have been more beneficial to the outcome of projects in terms of satisfying policy goals. It appeared that State bodies are more concerned with the administrative side of these projects. Technical and project managerial aspects are usually left for their consultants, either public or private. This caused a serious detachment of control and therefore difficulties and shortcomings in using the construction procurement of local public projects as a policy tool. The main findings of the analysis were based on taxonomy of documentary data collected in the case studies, which assisted in generating conclusions linking back to the theory of the three research elements mentioned above. Finally recommendations along the lines of enhancing transparency, the communication process, the need for a comprehensive State guidelines and the need for vocational education and training to participating State bodies were presented as an attempt to inform and possibly assist academics and Libyan policy makers to achieve positive and fruitful goals in local construction projects through good construction procurement policy making and implementation.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Process of equilibration in many-body isolated systems: Diagonal versus thermodynamic entropy

As recently manifested [1], the quench dynamics of isolated quantum systems consisting of a finite number of particles, is characterized by an exponential spreading of wave packets in the many-body Hilbert space. This happens when the inter-particle interaction is strong enough, thus resulting in a chaotic structure of the many-body eigenstates considered in the non-interacting basis. The semi-analytical approach used here, allows one to estimate the rate of the exponential growth as well as the relaxation time, after which the equilibration (thermalization) emerges. The key ingredient parameter in the description of this process is the width \u393 of the local density of states (LDoS) defined by the initially excited state, the number of particles and the interaction strength. In this paper we show that apart from the meaning of \u393 as the decay rate of survival probability, the width of the LDoS is directly related to the diagonal entropy and the latter can be linked to the thermodynamic entropy of a system equilibrium state emerging after the complete relaxation. The analytical expression relating the two entropies is derived phenomenologically and numerically confirmed in a model of bosons with random two-body interaction, as well as in a deterministic model which becomes completely integrable in the continuous limit

Dynamical aspects of thermalization in isolated systems of interacting Bose particles

"In this thesis we continue the study of the quench dynamics, payingattention to the new question of the relevance between the diagonalentropy related to an initially excited state, and the thermodynamicentropy emerging in the process of thermalization. We show numer-ically and describe semi-analytically that there is a one-to-one corre-spondence between them, with some corrections due to the differentsize between interacting and non-interacting energy spectra. This re-markable result holds both for the TBRI model with finite number ofbosons, and for the model originated from the celebrated Lieb-Liniger(LL) model"

Synthesis and study the structure, optical, thermal and dielectric properties of promising Glycine Copper Nitrate (GCN) single crystals

Four novel single crystals of α-glycine and γ-glycine doped by copper nitrate: (Glycine)1−X (Cu(NO3)2·3H2O)X abbreviated as (GCN1, GCN2, GCN3, GCN4) were prepared from aqueous solution by the slow evaporation method. Four doping concentrations: x = 0.005, 0.01, 0.02 and 0.04 of hydrated copper nitrate were used. The crystals were studied using powder X-ray diffraction (PXRD), Fourier Transform Infrared Spectroscopy (FTIR), and UV–Vis spectroscopy. The PXRD patterns showed that crystals containing high concentration of Cu(NO3)2·3H2O have triclinic or monoclinic structure. The lattice parameters for all the prepared crystals were found to be in a good agreement with that found in the crystallographic open database (COD). The functional groups of the crystals were determined from FTIR spectra and the optical band gaps were calculated from UV–Vis spectroscopy technique. The properties of the crystals was found to be concentration dependent on copper nitrate salt. The refractive index (n) for all GCN crystals were found around 1.88 in the region of the wavelength: 800–1000 nm, while the least value of n ≈ 1.72 was determined in the visible region of electromagnetic magnetic radiation. The decomposition point of GCN single crystals was identified by a narrow, and sharp peak of differential scanning calorimetry (DSC) curves. The phase transition temperature at 203 °C was observed for GCN2 crystals, is probably due to the transformation from γ-glycine to α-glycine. The dielectric study showed a peak around 30 °C (Curie temperature) that is a characteristic of ferroelectric crystals and the consistency of the dielectric constant at 90 °C indicated glass transition. Photoluminescence spectra of GCN crystals that were recorded at the excitation wavelength of 280 nm showed a maximum emission peaks around 345 nm. This finding indicated that these single crystals can be successfully used for NLO applications. Keywords: Semiorganic crystals, Glycine Copper Nitrate (GCN), XRD, UV–Vis and FTIR spectr

Spectrum statistics in the integrable Lieb-Liniger model

We address the old and widely debated question of the spectrum statistics of integrable quantum systems, through the analysis of the paradigmatic Lieb-Liniger model. This quantum many-body model of one-dimensional interacting bosons allows for the rigorous determination of energy spectra via the Bethe ansatz approach and our interest is to reveal the characteristic properties of energy levels in dependence of the model parameters. Using both analytical and numerical studies we show that the properties of spectra strongly depend on whether the analysis is done for a full energy spectrum or for a single subset with fixed total momentum. We show that the Poisson distribution of spacing between nearest-neighbor energies can occur only for a set of energy levels with fixed total momentum, for neither too large nor too weak interaction strength, and for sufficiently high energy. By studying long-range correlations between energy levels, we found strong deviations from the predictions based on the assumption of pseudorandom character of the distribution of energy levels

Synthesis and characterization of paramagnetic isotropic glycine manganese chloride single crystal with various dopant concentrations

Single crystals of α and γ glycine manganese chloride (GMC) were prepared using four dopant concentrations of MnCl2 in the molecular formula (C2H5NO2)1−x(MnCl2)x, where [x = 0.005, 0.02, 0.04, 0.05]. The crystals showed: nonlinear optical (NLO) activity, high transparency in UV–Vis. range of electromagnetic radiation, ferroelectric and dielectric characteristic with dielectric loss less than unity at high applied frequency. In addition, electron paramagnetic resonance were done for GMC4 crystal and shows a broad isotropic Lorentzian line (with g = 1.9692, ΔH = 416.2 G). The crystals possessed paramagnetic properties and were recommended in manufacturing of mini magnets. Keywords: Glycine manganese chloride (GMC), Ferroelectric, Electron paramagnetic resonance (EPR