Computer simulation of a laser designator in the operational environment

This thesis presents a computer simulation program designed to predict the performance of a laser designator in an operational environment. It uses aspects of Fourier optical theory, atmospheric modulation transfer function, atmospheric transmittance, and turbulence to analyze the spot size and the power on a target. The guidance system requires the specific power and spot size on a target to track it. So the optimum laser designator for special military purpose can be chosen by the output of this program for a particular atmospheric condition.http://archive.org/details/computersimulati00choiLieutenant, Republic of Korea NavyApproved for public release; distribution is unlimited

Viscoplasticity and damage mechanics models for rate-dependent materials and their application to ice

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1997.Includes bibliographical references.by Dong Ho Choi.Ph.D

Prediction of mechanical properties of Al alloys with change of cooling rate

The solidification process significantly affects the mechanical properties and there are lots of factors that affect the solidification process. Much progress has been made in the research on the effect of solidification on mechanical properties. Among them, the PF (Phase Field) model and CA (Cellular Automata) model are widely used as simulation methods which can predict nucleation and its growth, and the size and morphology of the grains during solidification. Although they can give accurate calculation results, it needs too much computational memory and calculation time. So it is difficult to apply the simulation to the real production process. In this study, a more practical simulation approach which can predict the mechanical properties of real aluminum alloys is proposed, by identifying through experiment the relationship between cooling rate and SDAS (Secondary Dendrite Arm Spacing) and mechanical properties. The experimentally measured values and the values predicted by simulation have relatively small differences and the mechanical properties of a variety of Al alloys are expected to be predicted before casting through use of the simulation

Takeover: A New Vertical Handover Concept for Net-Generation Heterogeneous Networks",

Abstract-One of the major challenges for seamless mobility in next-generation heterogeneous networks is vertical handover, which is the process of maintaining a mobile user's active connections as it changes its point of attachment. For seamless vertical handover, we introduce a new concept, Takeover, which enables a neighbor node to process requests of a mobile node. We develop protocol and operation for the takeover and apply it to vertical handover for next-generation heterogeneous networks. The proposed handover scheme using the takeover protocol reduces average handover latency and so enables a fast and seamless handover between two different access technologies. The simulation results show that the takeover-based vertical handover scheme achieves better performances compared with conventional handover schemes, with respect to handover delay, packet loss, and power consumption. I. INTRODUCTION Next-generation communication requires universal wireless access and ubiquitous computing through seamless personal and terminal mobility. One of the major challenges for seamless mobility is vertical handover, which is the process of maintaining a mobile user's active connections as it moves between different types of network. In order to achieve seamless vertical handover in heterogeneous network environments, it is necessary to guarantee service continuity and quality-ofservice (QoS), which means low latency and low packet loss during handover Generally, conventional handover schemes have been proposed by using pre-registration or post-registration method, which can reduce the handover delay because they separate layer 2 (L2) and L3 handovers and perform the L3 handover earlier or later than the L2 handove

Solid tumors of the pancreas can put on a mask through cystic change

<p>Abstract</p> <p>Background</p> <p>Solid pancreatic tumors such as pancreatic ductal adenocarcinoma (PDAC), solid pseudopapillary tumor (SPT), and pancreatic endocrine tumor (PET) may occasionally manifest as cystic lesions. In this study, we have put together our accumulated experience with cystic manifestations of various solid tumors of the pancreas.</p> <p>Methods</p> <p>From 2000 to 2006, 376 patients with pancreatic solid tumor resections were reviewed. Ten (2.66%) of these tumors appeared on radiological imaging studies as cystic lesions. We performed a retrospective review of medical records and pathologic findings of these 10 cases.</p> <p>Results</p> <p>Of the ten cases in which solid tumors of the pancreas manifested as cystic lesions, six were PDAC with cystic degeneration, two were SPT undergone complete cystic change, one was cystic PET, and one was a cystic schwannoma. The mean tumor size of the cystic portion in PDAC was 7.3 cm, and three patients were diagnosed as 'pseudocyst' with or without cancer. Two SPT were found incidentally in young women and were diagnosed as other cystic neoplasms. One cystic endocrine tumor was preoperatively suspected as intraductal papillary mucinous neoplasm or mucinous cystic neoplasm.</p> <p>Conclusions</p> <p>Cystic changes of pancreas solid tumors are extremely rare. However, the possibility of cystic manifestation of pancreas solid tumors should be kept in mind.</p

Design Optimization of Structural Acoustic Problems Using FEM-BEM

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76869/1/AIAA-2003-1630-545.pd

Effect of laser-dimpled titanium surfaces on attachment of epithelial-like cells and fibroblasts.

PurposeThe objective of this study was to conduct an in vitro comparative evaluation of polished and laserdimpled titanium (Ti) surfaces to determine whether either surface has an advantage in promoting the attachment of epithelial-like cells and fibroblast to Ti.Materials and methodsForty-eight coin-shaped samples of commercially pure, grade 4 Ti plates were used in this study. These discs were cleaned to a surface roughness (Ra: roughness centerline average) of 180 nm by polishing and were divided into three groups: SM (n=16) had no dimples and served as the control, SM15 (n=16) had 5-µm dimples at 10-µm intervals, and SM30 (n=16) had 5-µm dimples at 25-µm intervals in a 2 × 4 mm(2) area at the center of the disc. Human gingival squamous cell carcinoma cells (YD-38) and human lung fibroblasts (MRC-5) were cultured and used in cell proliferation assays, adhesion assays, immunofluorescent staining of adhesion proteins, and morphological analysis by SEM. The data were analyzed statistically to determine the significance of differences.ResultsThe adhesion strength of epithelial cells was higher on Ti surfaces with 5-µm laser dimples than on polished Ti surfaces, while the adhesion of fibroblasts was not significantly changed by laser treatment of implant surfaces. However, epithelial cells and fibroblasts around the laser dimples appeared larger and showed increased expression of adhesion proteins.ConclusionThese findings demonstrate that laser dimpling may contribute to improving the periimplant soft tissue barrier. This study provided helpful information for developing the transmucosal surface of the abutment