UV-filtered fermionic Monte Carlo

The short-range modes of the fermionic determinant can be absorbed in the gauge action using the loop expansion. The coefficients of this expansion and the zeroes of the polynomial approximating the remainder can be optimized by a simple, practical method. When the multiboson approach is used, this optimization results in a faster simulation with fewer auxiliary fields.Comment: typo (solid dotted line) corrected; LATTICE98(algorithms

Successful delivery of mega-projects

textThe term "mega-projects" is generally used to describe those projects whose capital budgets exceed one billion dollars. Many recent studies assessing the performance of mega-projects have concluded that cost and schedule overruns are common in all industry segments and world regions. Mega-projects are of importance not only to the stakeholders involved in development and construction, but also to the societies, economies, and environments impacted by these projects. There are very few studies that provide guidance on the effective planning and execution of megaprojects. Given the enormous amount of capital dollars at stake and the prevailing trend towards poor performance, the Construction Industry Institute initiated Research Team 315 (RT 315), Successful Delivery of Mega-projects, to attempt to identify why these failures happen and what can be done to prevent or reduce mega-project performance failures. The primary research question the team was tasked to find answer was: "What sorts of changes in project development and execution are needed to increase the likelihood of success on mega-projects?" After conducting a thorough literature review the RT finalized the following two hypothesis to validate (1) there are factors that have higher occurrence and performance impacts on mega-projects. (2) These factors require changes in mega-project planning and execution to improve the chances of successful outcomes. Through preliminary interviews, surveys, follow up interviews and case studies, the research identified 34 impact factors with high occurrence and high negative performance impact on mega-projects. The research also prioritized the most impactful factors that should be avoided or mitigated to increase the likelihood of successful mega-project outcomes. The research went deeper by identifying specific case examples of how the negative impacts might manifest. Furthermore, for each of the factors, the research identified specific mitigation strategies and recommendations that should be adopted during front-end-planning and execution. All of these results have been compiled into an Excel-based Implementation Resource, IR 315-2 Mega-Project Assessment of Criticality Tool (MPACT). MPACT provides project teams the means to a structured assessment process of critical factors on mega-projects, enabling more accurate and thorough mitigation planning on these impact factors, in order to improve mega-project performance.Civil, Architectural, and Environmental Engineerin

Full QCD with the L\"uscher local bosonic action

We investigate L\"uscher's method of including dynamical Wilson fermions in a lattice simulation of QCD with two quark flavours. We measure the accuracy of the approximation by comparing it with Hybrid Monte Carlo results for gauge plaquette and Wilson loops. We also introduce an additional global Metropolis step in the update. We show that the complexity of L\"uscher's algorithm compares favourably with that of the Hybrid Monte Carlo.Comment: 21 pages Late

Non-hermitian Exact Local Bosonic Algorithm for Dynamical Quarks

We present an exact version of the local bosonic algorithm for the simulation of dynamical quarks in lattice QCD. This version is based on a non-hermitian polynomial approximation of the inverse of the quark matrix. A Metropolis test corrects the systematic errors. Two variants of this test are presented. For both of them, a formal proof is given that this Monte Carlo algorithm converges to the right distribution. Simulation data are presented for different lattice parameters. The dynamics of the algorithm and its scaling in lattice volume and quark mass are investigated.Comment: 32 pages, LaTex, 8 ps figure

Hadron wave functions and the issue of nucleon deformation

Using gauge invariant hadronic two- and three- density correlators we extract information on the spatial distributions of quarks in hadrons, and on hadron shape and multipole moments within quenched lattice QCD. Combined with the calculation of N to Delta transition amplitudes the issue of nucleon deformation can be addressed.Comment: 4 pages, 7 figures. Talk presented at the PANIC02 conference, Sept. 30 - Oct. 4, 2002, Osaka, Japan. Discussion of the N to Delta results modifie

Microcanonical Lattice Gas Model for Nuclear Disassembly

Microcanonical calculations are no more difficult to implement than canonical calculations in the Lattice Gas Model. We report calculations for a few observables where we compare microcanonical model results with canonical model results.Comment: 7 pages, Revtex, 3 postscript figure

Model of multifragmentation, Equation of State and phase transition

We consider a soluble model of multifragmentation which is similar in spirit to many models which have been used to fit intermediate energy heavy ion collision data. We draw a p-V diagram for the model and compare with a p-V diagram obtained from a mean-field theory. We investigate the question of chemical instability in the multifragmentation model. Phase transitions in the model are discussed.Comment: Revtex, 9 pages including 6 figures: some change in the text and Fig.

Charged Particle with Magnetic Moment in the Aharonov-Bohm Potential

We considered a charged quantum mechanical particle with spin ${1\over 2}$ and gyromagnetic ratio $g\ne 2$ in the field af a magnetic string. Whereas the interaction of the charge with the string is the well kown Aharonov-Bohm effect and the contribution of magnetic moment associated with the spin in the case $g=2$ is known to yield an additional scattering and zero modes (one for each flux quantum), an anomaly of the magnetic moment (i.e. $g>2$) leads to bound states. We considered two methods for treating the case $g>2$. \\ The first is the method of self adjoint extension of the corresponding Hamilton operator. It yields one bound state as well as additional scattering. In the second we consider three exactly solvable models for finite flux tubes and take the limit of shrinking its radius to zero. For finite radius, there are $N+1$ bound states ($N$ is the number of flux quanta in the tube).\\ For $R\to 0$ the bound state energies tend to infinity so that this limit is not physical unless $g\to 2$ along with $R\to 0$. Thereby only for fluxes less than unity the results of the method of self adjoint extension are reproduced whereas for larger fluxes $N$ bound states exist and we conclude that this method is not applicable.\\ We discuss the physically interesting case of small but finite radius whereby the natural scale is given by the anomaly of the magnetic moment of the electron $a_e=(g-2)/2\approx 10^{-3}$.Comment: 16 pages, Latex, NTZ-93-0

Autocorrelation in Updating Pure SU(3) Lattice Gauge Theory by the use of Overrelaxed Algorithms

We measure the sweep-to-sweep autocorrelations of blocked loops below and above the deconfinement transition for SU(3) on a $16^4$ lattice using 20000-140000 Monte-Carlo updating sweeps. A divergence of the autocorrelation time toward the critical $\beta$ is seen at high blocking levels. The peak is near $\beta$ = 6.33 where we observe 440 $\pm$ 210 for the autocorrelation time of $1\times 1$ Wilson loop on $2^4$ blocked lattice. The mixing of 7 Brown-Woch overrelaxation steps followed by one pseudo-heat-bath step appears optimal to reduce the autocorrelation time below the critical $\beta$. Above the critical $\beta$, however, no clear difference between these two algorithms can be seen and the system decorrelates rather fast.Comment: 4 pages of A4 format including 6-figure

Incorporating Radial Flow in the Lattice Gas Model for Nuclear Disassembly

We consider extensions of the lattice gas model to incorporate radial flow. Experimental data are used to set the magnitude of radial flow. This flow is then included in the Lattice Gas Model in a microcanonical formalism. For magnitudes of flow seen in experiments, the main effect of the flow on observables is a shift along the $E^*/A$ axis.Comment: Version accepted for publication in Phys. Rev. C, Rapid Communicatio