Quantum transport in semiconductor quantum dot superlattices: electron-phonon resonances and polaron effects

Electron transport in periodic quantum dot arrays in the presence of interactions with phonons was investigated using the formalism of nonequilibrium Green's functions. The self-consistent Born approximation was used to model the self-energies. Its validity was checked by comparison with the results obtained by direct diagonalization of the Hamiltonian of interacting electrons and longitudinal optical phonons. The nature of charge transport at electron -- phonon resonances was investigated in detail and contributions from scattering and coherent tunnelling to the current were identified. It was found that at larger values of the structure period the main peak in the current -- field characteristics exhibits a doublet structure which was shown to be a transport signature of polaron effects. At smaller values of the period, electron -- phonon resonances cause multiple peaks in the characteristics. A phenomenological model for treatment of nonuniformities of a realistic quantum dot ensemble was also introduced to estimate the influence of nonuniformities on current -- field characteristics

Estimation of number of runaway electrons per avalanche in Earth's atmosphere

The connection between thunderstorms and relativistic runaway electron avalanches is an important topic that has attracted the attention of many researchers. Among other things, there are a lot of various simulations of the dynamics of electron avalanches. This article was written mostly in response to the article "The critical avalanche of runaway electrons" by Evgeny Oreshkin et al, which shows rather large numbers for an estimate of the number of runaway electrons, but it also contains the results of our own simulation and comparison with other papers

Wireless smart shipboard sensor network

This thesis studies the feasibility of developing a smart shipboard sensor network. The objective of the thesis is to prove that sensors can be made smart by keeping calibration constants and other relevant data such as network information stored on the sensor and a server computer. Study will focus on the design and implementation of an Ipsil IP(micro)8930 microcontroller, which is then connected, by the standard TCP/IP implementation, to a network where the sensor information can be seen using a web page. The information to make the sensor "smart" will be stored on the Ipsil chip and server computer and can by accessed by a HTML based program. By taking pre-computed calibration constants that minimize the measurement errors and writing them through the web page stored in the Ipsil chip's EEPROM, the calibrated sensor reading can be calculated. The expected contribution from the research effort would be a reduction in manpower, increased efficiency, and a greater awareness of plant and equipment operation among naval vessels, specifically the DDX. Hardware is relatively inexpensive, reliable, and COTS (Commercial Off the Shelf) available. If implemented, a Smart Shipboard Sensor Network would allow the watch standers, CHENG, OOD, and CO, to all see the same information about the ship.s engineering plant and equipment. A prototype sensor test bed was constructed in the laboratory, which consists of an Ipsil IP(micro)8930 microcontroller, a Linksys LAN router, and a Dell Inspiron 9300 laptop. The newly developed smart sensor was successfully demonstrated.http://archive.org/details/wirelesssmartshi109451756Approved for public release; distribution is unlimited

Re-Purpose

I would often take breaks from studying by walking along the beach, collecting any good seashells I would find. I started using them as plant holders, and enjoyed the hermit crab-like appearance