Equation of state of asymmetric nuclear matter: a VMC study

A Variational Monte Carlo (VMC) method is employed to investigate the properties of symmetric and asymmetric nuclear matter. The realistic Urbana V ₁₄ twonucleon interaction potential of Lagaris and Pandharipande was used to describe the microscopic interactions. Also, many body interactions are included as a density dependent term in the potential. Total kinetic and potential energies per particle are calculated for asymmetric nuclear matter by VMC method at various densities and isospin asymmetry parameters. The results are compared with data found in literature, and it was observed that the results obtained in this study reasonably agree with the results found in the literature. Also, the symmetry energy and incompressibility factor of the nuclear matter were obtained. The results obtained are in good agreement with those obtained by various authors with different methods and techniques.     

Assigning cross-trained workers to departments: A two-stage optimization model to maximize utility and skill improvement

We develop a general framework that is applicable in both manufacturing and service settings for assigning cross-trained workers across departments. The framework consists of a two-stage optimization model where two objective functions, departmental utility and skill improvement, are considered sequentially. Departmental utility is a function of departmental labor shortage and the first-stage optimization model maximizes total departmental utility subject to typical assignment constraints. The second stage model seeks to maximize total skill improvement, which is quantified by a hyperbolic learning curve, while trying not to deviate from the utility level obtained during the first stage optimization. Our computational experiments suggest that incorporating the skill improvement function explicitly in the model results in significant improvement in the total skill level of the workforce and thus leads to more effective worker assignments.     

Molecular structure and vibrational spectra of 4-, 5-, 6-chloroindole

The molecular geometry, IR intensities, harmonic and anharmonic vibrational frequencies of 4-, 5-, 6-chloroindole in the ground state were calculated by DFT/B3LYP level of theory using the 6-31G (d, p) basis set. To give complete and reasonable vibrational assignments, the normal coordinate analysis has been performed for 4-chloroindole, 5-chloroindole and 6-chloroindole. The effect of position of chloro atom on the molecular properties (electron density, dipole moments and energies) of the indole aromatic system is examined on the basis of calculation data for 4-, 5- and 6-chloroindoles.     

Linear programming with fuzzy parameters: An interactive method resolution

This paper proposes a method for solving linear programming problems where all the coefficients are, in general, fuzzy numbers. We use a fuzzy ranking method to rank the fuzzy objective values and to deal with the inequality relation on constraints. It allows us to work with the concept of feasibility degree. The bigger the feasibility degree is, the worst the objective value will be. We offer the decision-maker (DM) the optimal solution for several different degrees of feasibility. With this information the DM is able to establish a fuzzy goal. We build a fuzzy subset in the decision space whose membership function represents the balance between feasibility degree of constraints and satisfaction degree of the goal. A reasonable solution is the one that has the biggest membership degree to this fuzzy subset. Finally, to illustrate our method, we solve a numerical example.     

Generators for semigroup of Lipman

There is a correspondence between functions in the maximal ideal of the local ring of a rational singularity and certain positive divisors supported on the exceptional fiber of a resolution of the singularity. Here we give an algorithm to obtain a generating set over ℤ of these divisors.     

Two Electrons in a Quantum Dot: A Unified Approach

Low-lying energy levels of two interacting electrons confined in a two-dimensional parabolic quantum dot in the presence of an external magnetic field have been revised within the frame of a novel model. The present formalism, which gives closed algebraic solutions for the specific values of magnetic field and spatial confinement length, enables us to see explicitly individual effects of the electron correlation.     

Kronecker representation and decompositional analysis of closed queueing networks with phase-type service distributions and arbitrary buffer sizes

Two approximative fixed-point iterative methods based on decomposition for closed queueing networks with Coxian service distributions and arbitrary buffer sizes are extended to include phase-type service distributions. The irreducible Markov chain associated with each subnetwork in the respective decompositions is represented hierarchically using Kronecker products. The two methods are implemented in a software tool capable of computing the steady-state probability vector of each subnetwork by a multilevel method at each fixed-point iteration and are compared with other methods for accuracy and efficiency. Numerical results indicate that there is a niche filled by the two approximative methods. The authors thank Jean-Michel Fourneau for pointing out Marie’s method and Brouwer’s fixed-point theorem. The first author gratefully acknowledges grant TüBA-GEBİP from the Turkish Academy of Sciences.     

Analysis of meeting protocols by formalisation, simulation, and verification

Organizations depend on regular meetings to carry out their everyday tasks. When carried out successfully, meetings offer a common medium for participants to exchange ideas and make decisions. However, many meetings suffer from unfocused discussions or irrelevant dialogues. To study meetings in detail, we first formalize general properties of meetings and a generic meeting protocol to specify how roles in a meeting should interact to realize these properties. This generic protocol is used as a starting point to study real-life meetings. Next, an example meeting is simulated using the generic meeting protocol. The general properties are formally verified in the simulation trace. Next, these properties are also verified formally against empirical data of a real meeting in the same context. A comparison of the two traces reveals that a real meeting is more robust since when exceptions happen and the rules of the protocol are violated, these exceptions are handled effectively. Given this observation, a more refined protocol is specified that includes exception-handling strategies. Based on this refined protocol a meeting is simulated that closely resembles the real meeting. This protocol is then validated against another set of data from another real meeting. By iteratively adding exception handling rules, the protocol is enhanced to handle a variety of situations successfully.     

On system reliability in stress–strength setup

In this paper we study stress–strength reliability for a general coherent system. The exact expression as well as bounds and approximations for system reliability are presented. We also illustrate the estimation procedure for exponential stress–strength distributions.