On f(R) gravity

A review of the new of the problem of dark energy using modified gravity approach is considered. An explanation of the difficulties facing modern cosmology is given and different approaches are presented. We show why some models of gravity may suffer of instabilities and how some are inconsistent with observations.Comment: 5 pages, 0 figuers. arXiv admin note: text overlap with arXiv:1401.0046 by other author

Improving Passing Lane Safety and Efficiency for Alaska’s Rural Non‐divided Highways

INE/AUTC 14.0

Design of Digital Model for Re-Planning of Informal Settlements Using Geographic Information Systems

The process of re-planning settlements is a complex process, governed by technical foundations, legal regulations, procedures and practical steps to improve and develop these settlements to be at the perfect planning level, with minimum damages as much as possible. Execution of this process manually leads to slow down the solution with disconnected procedures and sometimes to increase the complexity of the problem by adding new extension of informal settlements, losing time, effort, cost and decrease the accuracy .In this research a new method had been proposed depending on digital systems to execute re-planning process by analyzing the foundations and regulations that govern the re-planning process and design the required digital solutions for its implementation applying the analysis tools of geographic information systems softwares together with its capabilities of input process of spatial data and their attributes in one digital database which enables its efficient integration, quick retrieval, ease of analysis and presentation. This method contributes in making re-planning process easy, quickly, secured, precise and of low cost.Aerial photographs had been used as a source of spatial data, non spatial attributes had been collected from the field using forms designed for this purpose and ArcGis software had been used to execute the steps of the process in the study area. Finally a digital re-planning model for the informal settlements had been designed to be as a guidance to execute the same steps for other areas by changing the data only

Study of Radon Concentrations In Some Of Public Ground Water Wells, Sana\u27a - Yemen

This study aims to assess radon-222 concentration levels in public ground water wells in Sana\u27a city, Yemen. Forty-three well water samples were collected from the study area. The alpha spectroscopy method was used to measure the samples using a RAD7 detector. The radon concentrations were in the range from 0.82 ± 0.38 Bq/L to 38.73 ± 2.98 Bq/L. A moderate correlation of radon levels with aquifer type was observed. Also, weak correlations of radon levels with electric conductivity, pH, and temperature, and no correlation with measured heavy metals were observed. Annual effective dose rates () were calculated and were found to be in the range from 0.006 to 0.283 mSv/y. Also, ion analysis of heavy metals was carried out. The analysis shows the maximum concentrations of copper, zinc, arsenic, and lead in groundwater samples were 0.5 mg/L, 0.58 mg/L, 0.7 mg/L, and 0.5 mg/L respectively

Modular and Distributed Verification of SysML Activity Diagrams

International audienceModel-based development for complex system design has been used to support the increase of systems complexity. SysML is a modeling language that allows a system description with various integrated diagrams, but SysML lacks formality for the requirement verification. Translating SysML-based specification into Petri nets allows to enable rigorous system analysis. However, for complex systems, we have to deal with the state space explosion problem. In this paper, we propose new approach to allow a modular and distributed verification of SysML Activity Diagram basing on the derived Petri net