Comparison of the Buckley-Leverett technique with a numerical simulation model containing heterogeneity and capillary pressure

A numerical model for a linear, two-phase fluid flow system has been developed with the capabilities of accounting for heterogeneity and capillarity. The model developed is general enough to analyze either water-oil or gas-oil systems. A hypothetical petroleum reservoir (containing only water and oil) under water flood was studied. The results for the homogeneous, no capillary pressure case were found to be similar to those obtained by the Buckley-Leverett technique. The study shows that the Buckley-Leverett is accurate even for a certain degree of heterogeneity. Also, capillarity does not substantially alter the results for the system studied. The results obtained using the mathematical model are considered more realistic where variations in a number of parameters or systems of variable geometry are involved --Abstract, page ii

Channels Reallocation In Cognitive Radio Networks Based On DNA Sequence Alignment

Nowadays, It has been shown that spectrum scarcity increased due to tremendous growth of new players in wireless base system by the evolution of the radio communication. Resent survey found that there are many areas of the radio spectrum that are occupied by authorized user/primary user (PU), which are not fully utilized. Cognitive radios (CR) prove to next generation wireless communication system that proposed as a way to reuse this under-utilised spectrum in an opportunistic and non-interfering basis. A CR is a self-directed entity in a wireless communications environment that senses its environment, tracks changes, and reacts upon its findings and frequently exchanges information with the networks for secondary user (SU). However, CR facing collision problem with tracks changes i.e. reallocating of other empty channels for SU while PU arrives. In this paper, channels reallocation technique based on DNA sequence alignment algorithm for CR networks has been proposed.Comment: 12 page

Cross Layer Aware Adaptive MAC based on Knowledge Based Reasoning for Cognitive Radio Computer Networks

In this paper we are proposing a new concept in MAC layer protocol design for Cognitive radio by combining information held by physical layer and MAC layer with analytical engine based on knowledge based reasoning approach. In the proposed system a cross layer information regarding signal to interference and noise ratio (SINR) and received power are analyzed with help of knowledge based reasoning system to determine minimum power to transmit and size of contention window, to minimize backoff, collision, save power and drop packets. The performance analysis of the proposed protocol indicates improvement in power saving, lowering backoff and significant decrease in number of drop packets. The simulation environment was implement using OMNET++ discrete simulation tool with Mobilty framework and MiXiM simulation library.Comment: 8 page

Colour Doppler evaluation of varicose veins

Background: Varicose veins are irreversibly dilated epifascial and perforating veins resulting from degenerative vascular wall changes, Depending on the aetiology, they are classified into Primary & Secondary forms. In the present clinical prospective studies, we evaluated the impact of ultrasound examinations on the pre-operative diagnosis of varicose veins and feasibility & efficacy of ultrasound.Methods: The current prospective study was conducted in the department of general surgery, Pt. J.N.M. College and associated Dr. BRAM Hospital Raipur, during a period form 1st august 2006 to 15th Nov 2007. Detail history was taken from patient as appropriate. A thorough clinical examination was done. The patients were then subjected to the series of investigations. The routine investigations were performed. Then all the patients were submitted for colour Doppler study. Other clinical diagnostic tests were also done. Other relevant examinations were also performed. The patients were then submitted for colour Doppler examination of lower limb with the help of Department of radiology. The groin and both lower limb scanned for seeking the common femoral, superficial femoral, popliteal, short saphenous, peroneal, anterior and posterior tibial veins. Any reflux at saphenous-femoral junction, dilatation and tortuousity as veining, reversal of flow, to locate the incompetent perforators.Results: The study included patients from 10-70 years of age group. The incidence was maximum (48%) in 31-50 yrs of age group. Sex wise distribution was nearly M: F- 5.25: 1. In our study, male appear to be more prone for the development of varicosity (84%). In our study it was found that maximum incidence noted in low socioeconomic status was 56%, second most common incidence noted in middle socioeconomic status (40%). Out of 25 patients one patient had associated thrombosis. In our study varicose vein was associated with anaemia 32%. Out of 25 patients, two patients received surgical management and 23 were managed conservatively.Conclusions: Duplex ultrasound scanning is non-invasive, early, safe and sensitive investigation of choice.