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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

SAR Reduction on a Portable Device Using Intelligent Metamaterial

Wang, Yi-jen 28 July 2010 (has links)
In this thesis, intelligent metamaterial was designed to reduce the peak specific absorption rate (SAR) value. Intelligent metamaterial means that when the antenna is far away from a human head, the metamaterial behaves like air and it does not affect the antenna performance; when the antenna is close to a human head, however, the metamaterial acts like a single negative (SNG) material. We designed two kinds of intelligent metamaterial structures. One makes use of impedance mismatching, and the other makes use of the frequency band shift property to reduce the peak SAR value at the operating frequency. The former structure is broadband, and it can reduce the peak SAR value by 56.7%. The latter structure has a much smaller size compared to the former one, and it is suitable for cellular phone applications. The peak SAR value can be reduced by 40% using the latter structure. The proposed two kinds of the intelligent metamaterial structures do not affect the antenna performance. Finally, the intelligent metamaterial has been applied to a cellular phone. The dimension of the intelligent metamaterial is only 40 mm ¡Ñ 20 mm ¡Ñ 0.8 mm. The intelligent metamaterial does not affect the antenna performance when the antenna is far away from a human head. When the antenna is close to a human head, the peak SAR is reduced by 41.7%.
2

Lokalizace osob v budovách / The localization of the persons in buildings

Noha, Jan January 2016 (has links)
This work presents design of indoor location system. The work is divided into several parts. The first part of this work presents available technologies in section of indoor location system. There are explained principles of elaboration for determine position. There is also description of several manufacturer systems. In the next part is described design of indoor localization system. There are description components of locator and there is described design of the printed circuit board. The last part is concentrating to construction and testing of locator.
3

Developing an Interactive Web-Based Database for Teaching Plant Materials

Weerasinghe, Kanchana S 17 May 2014 (has links)
In today’s increasingly fast-moving, complex, and competitive world, the need for flexibility and creativity in teaching and learning is crucial. For that reason, innovative educational methods should be introduced. In education, web-based learning and portable devices are emerging as teaching and learning aids which can be efficient and effective tools. Learning use and identification of ornamental plants are the main objectives of the plant materials courses offered by Department of Plant and Soils Sciences at Mississippi State University (MSU). The professors, teaching assistants (TA), and students use the MSU gardens to study and identify ornamental plant species. This can be time consuming for both instructors and students. This research developed an automated web-based database system to deliver information on the ornamental plants in the MSU gardens. Apache, MySQL, PHP, JavaScript, Dreamweaver, and Photoshop software were used to develop this application in the Windows environment and information about each plant was entered into the database. Plant locations were given by longitude and latitude coordinates and linked to Google maps. Quick Response codes(QR code) were created to directly access ornamental plant information at the field. This database may function as a virtual TA for the plant materials courses and as an information source for the public. Users can search the ornamental plant information and determine the location of plants using a computer or mobile device. Plant information can be retrieved from the field by a smart phone with a QR code reader. To evaluate the effectiveness and efficiency of developed automated system, an experimental study and questionnaire survey were designed.
4

Development of a portable aerosol collector and spectrometer (PACS)

Cai, Changjie 01 May 2018 (has links)
The overall goal of this doctoral dissertation is to develop a prototype instrument, a Portable Aerosol Collector and Spectrometer (PACS), that can continuously measure aerosol size distributions by number, surface area and mass concentrations over a wide size range (from 10 nm to 10 µm) while also collecting particles with impactor and diffusion stages for post-sampling chemical analyses. To achieve the goal, in the first study, we designed, built and tested the PACS hardware. The PACS consists of a six-stage particle size selector, a valve system, a water condensation particle counter to measure number concentrations and a photometer to measure mass concentrations. The valve system diverts airflow to pass sequentially through upstream stages of the selector to the detectors. The stages of the selector include three impactor and two diffusion stages, which resolve particles by size and collect particles for chemical analysis. Particle penetration by size was measured through each stage to determine actual performance and account for particle losses. The measured d50 of each stage (aerodynamic diameter for impactor stages and geometric diameter for diffusion stages) was similar to the design. The pressure drop of each stage was sufficiently low to permit its operation with portable air pumps. In the second study, we developed a multi-modal log-normal (MMLN) fitting algorithm to leverage the multi-metric, low-resolution data from one sequence of PACS measurements to estimate aerosol size distributions of number, surface area, and mass concentration in near-real-time. The algorithm uses a grid-search process and a constrained linear least-square (CLLS) solver to find a tri-mode (ultrafine, fine, and coarse), log-normal distribution that best fits the input data. We refined the algorithm to obtain accurate and precise size distributions for four aerosols typical of diverse environments: clean background, urban and freeway, coal power plant, and marine surface. Sensitivity studies were conducted to explore the influence of unknown particle density and shape factor on algorithm output. An adaptive process that refined the ranges and step sizes of the grid-search reduced the computation time to fit a single size distribution in near-real-time. Assuming standard density spheres, the aerosol size distributions fit well with the normalized mean bias (NMB) of -4.9% to 3.5%, normalized mean error (NME) of 3.3% to 27.6%, and R2 values of 0.90 to 1.00. The fitted number and mass concentration biases were within ± 10% regardless of uncertainties in density and shape. With this algorithm, the PACS is able to estimate aerosol size distributions by number, surface area, and mass concentrations from 10 nm to 10 µm in near-real-time. In the third study, we developed a new algorithm–the mass distribution by composition and size (MDCS) algorithm–to estimate the mass size distribution of various particle compositions. Then we compared the PACS for measuring multi-mode aerosols to three reference instruments, including a scanning mobility particle sizer (SMPS), an aerodynamic particle sizer (APS) and a nano micro-orifice uniform deposit impactor (nanoMOUDI). We used inductively coupled plasma mass spectrometry to measure the mass of collected particles on PACS and nanoMOUDI stages by element. For the three-mode aerosol, the aerosol size distributions in three metrics measured with the PACS agreed well with those measured with the SMPS/APS: number concentration, bias = 9.4% and R2 = 0.96; surface area, bias = 17.8%, R2 = 0.77; mass, bias = -2.2%, R2 = 0.94. Agreement was considerably poorer for the two-mode aerosol, especially for surface area and mass concentrations. Comparing to the nanoMOUDI, for the three-mode aerosol, the PACS estimated the mass median diameters (MMDs) of the coarse mode well, but overestimated the MMDs for ultrafine and fine modes. The PACS overestimated the mass concentrations of ultrafine and fine mode, but underestimated the coarse mode. This work provides insight into a novel way to simultaneously assess airborne aerosol size, composition, and concentration by number, surface area and mass using cost-effective handheld technologies.
5

DS Universal Remote

Torres Gil, Miguel Ángel January 2007 (has links)
<p>The purpose of this thesis is to develop a remote control application for personal computers. This application will have two devices implied, the computer to be controlled and a small portable device that will be used as remote controller.</p><p>In this specific case, the portable device picked is the Nintendo DS, for reasons discussed later in this document that make this device interesting as a remote controller.</p><p>The application should allow the final user to create his own set of remote controllers for any computer application he wants to control, and also, to define the commands the application should perform. This makes the developed solution a full customizable universal remote controlling application.</p><p>The first step taken was to do a small research about what kind of devices and software are present actually for remote control applications, so the differences, advantages and disadvantages of using the Nintendo DS will be shown. Then the developed solution will be explained and tested, controlling some computer applications under different scenarios.</p>
6

DS Universal Remote

Torres Gil, Miguel Ángel January 2007 (has links)
The purpose of this thesis is to develop a remote control application for personal computers. This application will have two devices implied, the computer to be controlled and a small portable device that will be used as remote controller. In this specific case, the portable device picked is the Nintendo DS, for reasons discussed later in this document that make this device interesting as a remote controller. The application should allow the final user to create his own set of remote controllers for any computer application he wants to control, and also, to define the commands the application should perform. This makes the developed solution a full customizable universal remote controlling application. The first step taken was to do a small research about what kind of devices and software are present actually for remote control applications, so the differences, advantages and disadvantages of using the Nintendo DS will be shown. Then the developed solution will be explained and tested, controlling some computer applications under different scenarios.
7

Mobilní zdroje elektrické energie / Mobile Power Sources

Kvasnička, Karel January 2020 (has links)
Charging station; PV panel; accumulator; battery; lithium; LiFePO4; Arduino

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