2,497 research outputs found
Dark Matter in Universal Extra Dimension Models: vrs
We show that in a class of universal extra dimension models (UED), which
solves both the neutrino mass and proton decay problem, an admixture of KK
photon and KK right handed neutrinos can provide the required amount of cold
dark matter (CDM). This model has two parameters and ( is
the radius of the extra space dimensions and the extra neutral gauge boson
of the model). Using the value of the relic CDM density, combined with the
results from the cryogenic searches for CDM, we obtain upper limits on
of about 400-650 GeV and TeV, both being accessible to LHC. In
some regions of the parameter space, the dark matter-nucleon scattering cross
section can be as high as of cm, which can be probed by the next
round of dark matter search experiments.Comment: 13 pages, 2 figures; minor changes; to appear in Phys. Rev.
The Stable Manifold Theorem for Stochastic Differential Equations
We formulate and prove a {\it Local Stable Manifold Theorem\/} for stochastic
differential equations (sde's) that are driven by spatial Kunita-type
semimartingales with stationary ergodic increments. Both Stratonovich and
It\^o-type equations are treated. Starting with the existence of a stochastic
flow for a sde, we introduce the notion of a hyperbolic stationary trajectory.
We prove the existence of invariant random stable and unstable manifolds in the
neighborhood of the hyperbolic stationary solution. For Stratonovich sde's, the
stable and unstable manifolds are dynamically characterized using forward and
backward solutions of the anticipating sde. The proof of the stable manifold
theorem is based on Ruelle-Oseledec multiplicative ergodic theory
Reconciling the CAST and PVLAS Results
The PVLAS experiment has recently claimed evidence for an axion-like particle
in the milli-electron-Volt mass range with a coupling to two photons that
appears to be in contradiction with the negative results of the CAST experiment
searching for solar axions. The simple axion interpretation of these two
experimental results is therefore untenable and it has posed a challenge for
theory. We propose a possible way to reconcile these two results by postulating
the existence of an ultralight pseudo-scalar particle interacting with two
photons and a scalar boson and the existence of a low scale phase transition in
the theory.Comment: 4 pages, 2 figures; references update
A MULTI-STAKEHOLDER INDUSTRIAL PROJECTS SELECTION: AN ANALYTIC HIERARCHY PROCESS AND ZERO-ONE-GOAL PROGRAMMING APPROACH
This study uses Analytic Hierarchy Process (AHP) and Zero-One Goal Programming (ZOGP) to select the most favorable industrial projects from the viewpoints of three stakeholders, namely, govern mental, consultants and academics. Therefore, it is the purpose of this paper to help reach a consensus among the stakeholders for selecting certain projects using weights obtained by AHP as inputs to (ZOGP) model. This is first done by identifying the projects from each individual stakeholder's viewpoint. Further, an aggregate model that simultaneously combines the viewpoints of the three stakeholders is built assuming that the three stakeholders have equal weights. Results show that the aggregate model does strike a balance not only among the conflicting criteria, but more importantly, it strikes a balance among the different stakeholders. Therefore, the aggregate model would make it easier for stakeholders to reach a consensus
Goal Programming for Academic Plans Design
This article describes a project undertaken at the Islamic University in Gaza. The project aims at designing a general academic departmental plan of study using binary goal programming. The design process includes balancing the assignment of courses to semesters. Soft and hard constraints are first identified based on interviews with academic experts. Then, a model that uses multiple criteria programming is built and used to construct the plan of study of the industrial engineering department at the Islamic University in Gaza. To determine the weights of the criteria, the researcher attempted to use Analytic Hierarchy Process (AHP). However, after interviewing the experts, it was concluded that pre-emptive goal programming is recommended. The model was then solved using LP-Solve software. The resulting plan of study clearly outperforms the manually designed one. A comparison between the newly designed
Use of goal programming and integer programming for water quality management—A case study of Gaza Strip
This paper describes a project dealing with achieving an optimum mix of water from different underground wells, each having different amounts of nitrates and chlorides. The amounts of chlorides and nitrates in each of the wells may be higher or lower than the World Health Organization (WHO) standards. Therefore, the optimum mix would be the one that meets WHO standard which is 250 mg/l for chlorides and 50 mg/l for nitrates. A goal programming model was developed to identify the combination of wells along with the amounts of water from each well that upon mixing would result in minimizing the deviation of the amounts of chlorides and nitrates from the standards set by WHO. The output of the goal programming model along with the coordinates of the wells identified above was then used for a second model that determines the locations of the mixing points “reservoirs” in such a way that minimizes the total
Evaluating and benchmarking non-governmental training programs: an analytic hierarchy approach
This study uses Analytic Hierarchy Process (AHP) as a multi-criteria decision making technique for evaluating training programs. Critical factors characterizing successful training programs are first identified using interviews with experts along with questionnaires. Once the factors were identified, the hierarchy was constructed and the factors were ranked according to their importance with respect to achieving the overall goal set for training. Results show that, of these critical factors, content and trainer rank the highest, while logistics came last. Then, two existing non-governmental training programs are selected, evaluated, and compared. Moreover, and as requested by one of the administrations of one of the evaluated programs, a benchmarking alternative is derived based on the results of the two training programs. Finally, recommendations are given to each of these programs in particular and training programs in general, for possible areas of improvements based on the strengths and weaknesses of each program as compared to the benchmark
- …