Optical Phonon Limited High Field Transport in Layered Materials

An optical phonon limited velocity model has been employed to investigate high-field transport in a selection of layered 2D materials for both, low-power logic switches with scaled supply voltages, and high-power, high-frequency transistors. Drain currents, effective electron velocities and intrinsic cut-off frequencies as a function of carrier density have been predicted thus providing a benchmark for the optical phonon limited high-field performance limits of these materials. The optical phonon limited carrier velocities of a selection of transition metal dichalcogenides and black phosphorus are found to be modest as compared to their n-channel silicon counterparts, questioning the utility of these devices in the source-injection dominated regime. h-BN, at the other end of the spectrum, is shown to be a very promising material for high-frequency high-power devices, subject to experimental realization of high carrier densities, primarily due to its large optical phonon energy. Experimentally extracted saturation velocities from few-layer MoS2 devices show reasonable qualitative and quantitative agreement with predicted values. Temperature dependence of measured vsat is discussed and found to fit a velocity saturation model with a single material dependent fit parameter.Comment: 8 pages, 6 figure

Monthly and seasonal variation in beach profile along the coast of Tiruchendur and Kanyakumari, Tamilnadu, India

Beach profile survey has been carried out by the method described by Lafond and Prasada Rao (1954) and Emery (1961) between Tiruchendur and Kanyakumari beach, Tamilday, India. The average beach profile shapes in all stations are not identical. This is due to the large amount of sands that transported into the nearshore by longshore and cross-shore movement. In particular this difference is shown in the location of the high variability of heavy mineral distribution depicts the morphological changes. Record of monthly and seasonal beach profile obtained at the 10 beaches along the study area during the period between 2005 and 2006 yield an extensive dataset that could be used to determine the variations in the beach morphology and the processes responsible for the changes. Based on the beach profile measurements the changes were also critically examined and also the impact of intensive extraction of beach sand minerals along the beach profiles was investigated in order to know the morphological variation in the mining area.Se ha realizado el estudio del perfil de la playa entre Tiruchendur y Kanyakumari, Tamildau, India, siguiendo el método descrito por Lafond y Prasada Rao (1954) and Emery (1961). La media del perfil de la playa a lo largo del año no es la misma. Esto es debido a la gran cantidad de arenas transportadas hacia la costa mediante corrientes paralelas y transversales a la misma. En particular, esta diferencia se muestra en la alta variabilidad de distribución de minerales pesados en relación con los cambios morfológicos. El registro mensual y estacional de los cambios del perfil de la playa obtenido en 10 playas a lo largo de la zona de estudio durante el periodo comprendido entre 2005-2006 proporciona una información que podría ser utilizada para obtener la variación de las morfologías en las playas y las causas que lo producen. Los cambios en el perfil de la playa han sido también examinados en detalle en base a las medidas del perfil de la playa obtenidos, así como fue investigado el impacto producido por la intensiva extracción de minerales de la playa con el objetivo de conocer la variación de la morfología en la zona de actividad minera

A nonlocal connection between certain linear and nonlinear ordinary differential equations/oscillators

We explore a nonlocal connection between certain linear and nonlinear ordinary differential equations (ODEs), representing physically important oscillator systems, and identify a class of integrable nonlinear ODEs of any order. We also devise a method to derive explicit general solutions of the nonlinear ODEs. Interestingly, many well known integrable models can be accommodated into our scheme and our procedure thereby provides further understanding of these models.Comment: 12 pages. J. Phys. A: Math. Gen. 39 (2006) in pres

Attitude towards the Usage of Electronic Information Resources in Medical Library, University of Jaffna, Sri Lanka

Purpose- The purpose of the study is to find out whether there are any significant mean differences among personal characteristics such as readers’ type, gender, user category, age group and the year of study towards attitude of using electronic information resources in Medical Library, University of Jaffna, Sri Lanka during the year 2013. Research Design-The study used the questionnaire as a research instrument and a total of 258 usable responses were obtained using random sampling technique. Further, the study employs independent samples t-test and One-way ANOVA (f-test) for the purpose of data analysis. Findings- The results revealed that readers' type such as academic staff and students, the year of study of the students  and user category (Lecturer, Senior Lecturer, Professor and students) have shown significant mean difference towards the attitude of usage of  electronic information resources (P < 0.05). But, gender both male and female readers and age group have roughly same level of opinion, which is insignificant. Research Limitation-As the study was limited to the academic staff and medical students at the Faculty of Medicine, a challenge may occur in terms of generalization of the results widely. Originality-The findings of this research could be generalized to the studies similar to this category. Keywords: Attitude, Electronic Information Resources, Medical Library, University of Jaffna

QoS Evaluation of SIP Signalled VoIP Network Routed using MANET Routing Protocols

A Mobile ad hoc network MANET is a type of network which consists of group of mobile nodes which are wireless and do not have fixed architecture The nodes act as a router and depict the nature of dynamism The three different classification of protocols in MANETS supports different applications But to support real time applications like voice signalling and video signalling we require the most efficient protocol that gives the QoS mechanism Voice and video signalling demand to know the performance of different metrics in the network such as end-to-end delay overall throughput of network and jitter of the network This paper works on identifying and analyzing the performance of various protocols like AODV DSR OLSR and TORA which would help in fulfilling the mentioned need Voice over Internet Protocol VoIP also known as IP telephony is a class of technologies used to deliver voice and multimedia sessions over internet protocol network

Optimal area approach to intercomparing polarimetric radar rain-rate algorithms with gauge data, An

Includes bibliographical references (page 623).An optimal area method is described that is used as a basis for comparing KDP-, (KDP, ZDR)-, and Zh-based estimates of rain rates with gauge-measured rain rates. The location and dimensions of an elliptically shaped optimal area within the radar scan area surrounding the gauge are determined objectively via an rms error minimization of the difference between the KDP-based radar estimate and gauge data and via use of the spatial structure of the rms difference field itself. Four convective events were analyzed with rain rates in the range of 20-120 mm h-1, with two of the events containing marble-sized hail. The analysis shows that excellent results could be achieved using KDP-based rain-rate estimators