A FORMAL MODEL FOR ANALYZING THE SCR-STYLE REQUIREMENTS SPECIFICATIONS

Based on SCR(Software Cost Reduction), this paper presents a formal mOdel analyzingSCR-style requirements- This model mainly apply state trans1ation rules, semantic computing rules and attributes to define formal sementics of a tabular notation in the SCR requirements method, and may automatically analyze requirements specifications to be specified by the SCR method. Combining with a simp1eexample, this paper introduces how to analyze consistency and completeness of requirements specifica-tlons.

Probing time delay of strong-field resonant above-threshold ionization

The high-resolution three-dimensional photoelectron momentum distributions via above-threshold ionization(ATI)of Xe atoms are measured in an intense near circularly polarized laser field using velocity map imaging and tomography reconstruction. Compared to the linearly polarized laser field, the employed near circularly polarized laser field imposes a more strict selection rule for the transition via resonant excitation, and therefore we can selectively enhance the resonant ATI through certain atomic Rydberg states. Our results show the self-reference ionization delay, which is determined from the difference between the measured streaking angles for nonadiabatic ATI via the 4 f and 5 f Rydberg states, is 45.6 as. Our method provides an accessible route to highlight the role of resonant transition between selected states, which will pave the way for fully understanding the ionization dynamics toward manipulating electron motion as well as reaction in an ultrafast time scale.

The emergence and evolution of OpenStreetMap: a cellular automata approach

Collaborative mapping projects,such as OpenStreetMap(OSM),have received tremendous amounts of contributed data from voluntary participants over time.So far,most research efforts deal with data quality issues,but the OSM evolution across space and over time has not been noted.Therefore,this study is dedicated to the evolution of the contributed information in order to understand an emergent phenomenon of so-called collaborative contributing.The main objective of this paper is to monitor the evolutional pattern of OSM and predict potential future states through a cellular automata(CA)model.This is exceedingly relevant for numerous OSM-based applications.Descriptive spatiotemporal analysis of the contributions for the time period 2007–2012,using the city of Heidelberg(Germany)as a case study,reveals that early contributions are given three years after the launching of OSM,while after nearly six years,most of the areas are discovered.The simulation results for the validated CA model,predicting OSM states for 2014,provide clear evidence that most of the areas have been explored three years after people began mapping until 2010,and thereafter,the densification process has begun and will cover most parts of the city although the amount of contribution depends on the land use types.

Verifying Mutual Exclusion and Liveness Properties with Split Preconditions

This work is focused on presenting a split precondition approach for the modeling and proving the correctness of distributed algorithms. Formal specification and precise analysis of Peterson's distributed mutual exclusion algorithm for two process has been considered. The proof of properties like, mutual exclusion, liveness, and lockout-freedom have also been presented. Keywords distributed algorithms - state transition rule - mutual exclusion - weakest self-precondition - weakest co-operation - correctness Regular PaperAwadhesh Kumar Singh received the B.E. degree in computer science & engineering from Gorakhpur University, Gorakhpur, India in 1988. He received the M.E. and Ph.D. (Engg) degrees in the same area from Jadavpur University, Kolkata, India. He is a faculty member in Computer Engineering Department, National Institute of Technology, Kurukshetra, India. His present research interest is distributed systems.Anup Kumar Bandyopadhyay received the B.E. (Tel.E.), M.E. (Tel.E.), and Ph.D. (Engg) degrees from Jadavpur University, Calcutta, India in 1968, 1970 and 1983, respectively. From 1970 to 1972 he worked with the Microwave Antenna System Engineering Group of the Indian Space Research Organization. In 1972 he joined the Department of Electronics and Telecommuication Engineering, Jadavpur University, where he is currently a professor. His research interests include computer communication networks and distributed systems.