Near source modeling of pollutant emissions from an elevated source over an urban area under cross high ventilation

Due to the rapid urbanization of many cities around the world, industrial manufacturing plants have grown rapidly, thus leading to the release of large amounts of pollutants into the environment. This is a main reason for the degradation of the local air quality, resulting in an increasing risk of unfavorable sanitary conditions for city dwellers. Understanding the dispersion of pollutants in local population environments, meteorological conditions and other physical characteristics is fundamental for predicting and evaluating air quality. This paper provides comprehensive details on the study of flow patterns and pollutant dispersion processes in urban areas. Several factors which include building geometry, local atmospheric effects, structural obstructions, and velocity of exhaust pollutants, are examined considering field data, wind tunnel tests, operational simulation techniques, and computational fluid dynamics. Good agreements are noticeable. Simultaneous evolutions of the velocity, thermal and scalar mass fraction fields of the pollutant emitting from a three-dimensional elevated source around a rectangular obstacle placed on a turbulent boundary layer wall, and also downstream the obstacle have been successfully carried out. The most serious pollutant levels in urban areas under various high wind velocities are identified.

Miocene stratigraphy and structure of the East Bay Hills, California

ABSTRACT The structure and stratigraphy of the Miocene formations east of San Francisco Bay have been described in multiple studies for over a century. We integrated the results of past investigations and provide new data that improve understanding of formation age, the timing of deformation, and the amount of dextral displacement on selected faults. New geologic mapping and better age control show that formations previously inferred to be separate units of different ages are correlative, and new names are proposed for these units. Miocene structures associated with the development of the San Andreas transform system exerted significant control on Miocene deposition in the East Bay area. The developing structure created five distinct stratigraphic sections that are differentiated on the basis of differences in the stratigraphic sequence, lithology, and age. The stratigraphic changes are attributed to significant dextral displacement, syndepositional faulting, and distal interfingering of sediment from tectonically elevated source areas. New stratigraphic evaluations and age control show that prior to ca. 6 Ma, the developing fault system created local tectonically induced uplift as well as spatially restricted subbasins. Regional folding did not occur until after 6 Ma. Past evaluations have inferred significant dextral displacement on some of the faults in the East Bay. The spatial relationships between unique conglomerate clasts and known source areas, as well as the distribution of well-dated and unique tuffs, suggest that dextral displacement on some faults in the East Bay is less than previously reported.

Physics Based Analytical Modeling of Asymmetric Elevated Source Tunnel FET (AES-TFET) for Better Tunnel Junction Device (TJD) Performance

The authors have requested that this preprint be withdrawn due to erroneous posting.

Physics Based Analytical Modeling of Asymmetric Elevated Source Tunnel FET (AES-TFET) for Better Tunnel Junction Device (TJD) Performance

In this paper, a two-dimensional analytical model for asymmetric elevated source tunnel field effect transistor (AES-TFET) has been developed to obtain better tunnel junction device performance. Device physics based analytical modelling is performed by solving 2-D Poisson’s equation. Surface potential distribution, electric field variation and band-to-band tunneling (B2B) rate have been investigated by this numerical modelling. In our proposed structure, the source has been elevated (varied 2 nm to 6 nm) to incorporate corner effect; which boosts the carrier transport via thin tunneling barrier, with controlled ambipolar conduction. This eventually produces better source-channel interface tunneling for a n-channel AES-TFET structure. 2-D numerical device simulator (SILVACO TCAD) has been used for simulation work. The simulated graphical representations have been finally validated by analytical modelling of AES-TFET.

Estimation of Dispersion in an Open Channel from an Elevated Source Using an Upwind Local Meshless Method

Numerical solution of steady state partial differential equation (PDE) model is proposed using a stabilized local meshless method (SLMM). The PDE model under consideration is used to approximate longitudinal dispersion of suspended particles of turbulent flow moving with both zero and nonzero settling velocities. In the proposed technique, a shape parameter based SLMM is used to calculate effects of mean velocity and variable eddy diffusivity accurately. In the case of zero settling velocity, when particles are injected from a line source located at some height, numerical results confirm the experimental results. Numerical results of the SLMM also confirm numerical results produced by finite difference method (FDM) as well.