With the integration of multiaxis layered manufacturing and material removal (machining) processes, a hybrid system has more capability and flexibility to build complicated geometry with a single setup. Process planni...
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With the integration of multiaxis layered manufacturing and material removal (machining) processes, a hybrid system has more capability and flexibility to build complicated geometry with a single setup. Process planning to integrate the two different processes is a key issue. In this paper, an algorithm of adaptive slicing for a five-axis Laser Aided Manufacturing Process (LAMP) is summarized that can generate uniform and non-uniform thickness slices. A method to build a non-uniform (thickness) layer that utilizes two processes is presented, and an overall algorithm for integration is described. The newly developed algorithm implemented in the process planning helps the hybrid system build parts more efficiently.
This work describes a two-step pipelined 8b 240 MS/s 0.18 um CMOS ADC as one of embedded cells for highperformance displays requiring low-noise on-chip references and dual-mode inputs with the specifications of limite...
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The purpose of this paper is to visualize a still image and video on 3-dimensional medical image on the web using volume rendering board and VRML(Virtual Reality Modeling Language). Using VRML, the compressed 3-dimens...
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Conventional shot boundary detection (SBD) algorithms have limitations in handling video data that contain fast illumination changes or rapid motions of objects and background. This paper presents a SBD algorithm that...
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The field emission behavior of carbon nanotubes (CNTs) in terms of their potential applications in vacuum microelectronics has been studied extensively in recent years. CNTs have extraordinary strength, impressive the...
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ISBN:
(纸本)0780383974
The field emission behavior of carbon nanotubes (CNTs) in terms of their potential applications in vacuum microelectronics has been studied extensively in recent years. CNTs have extraordinary strength, impressive thermal and chemical stabilities and excellent electronic properties beneficial for making field emission cathodes. A vertically aligned CNT cathode is a beneficial geometrical structure for achieving high performance vacuum micro- and nano-electronic devices such as field emission diodes, triodes and flat panel displays. Although the vertical alignment of CNTs has been achieved in many ways[1-3], less experimentation has been conducted at ambient pressure using a simple tube furnace which would be a most promising method to mass produce CNTs by catalytic chemical vapor deposition (CVD). In this work, Ni catalytic film was deposited on SiO2 substrates and CNTs synthesis was performed in a quartz tube furnace. NH3 was applied with acetylene (C2H2) to produce vertically aligned CNTs. The catalyst deposition parameters and C2H2/NH3 flow rates are critical to the size and density of Ni catalytic particles, which strongly affect the morphology of as-grown CNTs. The temperature and pressure at which CNTs were grown were at 750°C and 1 atm., respectively. During the experiments, a mixture of Ar (80 vol.%) and H2 (20 vol.%) was introduced into the furnace at room temperature, the furnace was then heated to 750°C at the rate of 15°C/min. When the temperature was stabilized, NH3 was introduced as a processing reagent, followed by C 2H2, the carbon source. The effects of NH3 on the size and density of Ni particles were investigated, and the mechanism of CNT alignment was analyzed. Specifically, ammonia breaks larger catalyst particles into smaller ones, thereby increasing the particle density. The size of catalyst particles is critical, because CNTs cannot grow if the diameter of catalyst particles is far beyond the diffusion length of carbon atoms[4]. Moreover, NH3
Electric, telecommunications, water, gas and transportation utilities face severe challenges associated with a combination of technical, economic and social issues. To meet the educational needs for engineers and mana...
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Electric, telecommunications, water, gas and transportation utilities face severe challenges associated with a combination of technical, economic and social issues. To meet the educational needs for engineers and managers the University of Colorado at Boulder is proposing a novel integrated utilities management program for Master of engineering (ME) candidates. The ME program will consist of four interdisciplinary paths dealing with business, management and legal topics as they relate to federal and state regulatory issues and people-related leadership issues. The electric utilities option of this program will be centered on three core courses related to electric power generation/transmission and distribution, security and availability, quality and reliability, economics and environmental policy, and utility finance;two electives from a group of courses that address nuclear power, waste water, solid waste, telecommunications, renewable energies, data communication, fuels and case studies;and one capstone course. Courses will be taught both on campus and nationwide via the Center for Advanced engineering and Technology Education (CAETE) of the University of Colorado at Boulder.
The tour guide services are a LBS application that provides the information based on the location of users. The recent researches of the tour guide services focus on the context-sensitive computing, but the tour guide...
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