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1
iyer, vishwanath. "Broadband Impedance Matching of Antenna Radiators". Digital WPI, 2010. https://digitalcommons.wpi.edu/etd-dissertations/388.
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"In the design of any antenna radiator, single or multi-element, a significant amount of time and resources is spent on impedance matching. There are broadly two approaches to impedance matching; the first is the distributed impedance matching approach which leads to modifying the antenna geometry itself by identifying appropriate degrees of freedom within the structure. The second option is the lumped element approach to impedance matching. In this approach instead of modifying the antenna geometry a passive network attempts to equalize the impedance mismatch between the source and the antenna load. This thesis introduces a new technique of impedance matching using lumped circuits (passive, lossless) for electrically small (short) non-resonant dipole/monopole antennas. A closed form upper-bound on the achievable transducer gain (and therefore the reflection coefficient) is derived starting with the Bode-Fano criterion. A 5 element equalizer is proposed which can equalize all dipole/monopole like antennas. Simulation and experimental results confirm our hypothesis. The second contribution of this thesis is in the design of broadband, small size, modular arrays (2, 4, 8 or 16 elements) using the distributed approach to impedance matching. The design of arrays comprising a small number of elements cannot follow the infinite array design paradigm. Instead, the central idea is to find a single optimized radiator (unit cell) which if used to build the 2x1, 4x1, 2x2 arrays, etc. (up to a 4x4 array) will provide at least the 2:1 bandwidth with a VSWR of 2:1 and stable directive gain (not greater than 3 dB variation) in each configuration. Simulation and experimental results for a solution to the 2x1, 4x1 and 2x2 array configurations is presented. "
2
Luther, Justin. "Microstrip Patch Electrically Steerable Parasitic Array Radiators". Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5984.
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This dissertation explores the expansion of the Electrically Steerable Parasitic Array Radiator (ESPAR) technology to arrays using microstrip patch elements. Scanning arrays of two and three closely-coupled rectangular patch elements are presented, which incorporate no phase shifters. These arrays achieve directive radiation patterns and scanning of up to 26° with maintained impedance match. The scanning is effected by tunable reactive loads which are used to control the mutual coupling between the elements, as well as additional loads which compensate to maintain the appropriate resonant frequency. The design incorporates theoretical analysis of the system of coupled antennas with full-wave simulation. A prototype of the three-element array at 1 GHz is fabricated and measured to exhibit a maximum gain of 7.4 dBi with an efficiency of 79.1%. Further, the microstrip ESPAR is thoroughly compared to uniformly-illuminated arrays of similar size.
To satisfy the need for higher directivity antennas with inexpensive electronic scanning, the microstrip ESPAR is then integrated as a subarray. The three-element subcell fabrication is simplified to a single layer with an inverted-Y groove in the ground plane, allowing for DC biasing without the need for the radial biasing stubs or tuning stubs found in the two-layer design. The 1 GHz ESPAR array employs a corporate feed network consisting of a Wilkinson power divider with switchable delay line phase shifts, ring hybrid couplers, and achieves a gain of 12.1 dBi at boresight with &"177;20° scanning and low side lobes. This array successfully illustrates the cost savings associated with ESPAR subarray scanning and the associated reduction in required number of phase shifters in the RF front end.Ph.D.
Doctorate
Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering
3
Checketts, Gus Thomas. "Microchannel Radiator: an Investigation of Microchannel Technology with Applications in Automotive Radiator Heat Exchangers". Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc700005/.
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Microchannels have been used in electronics cooling and in air conditioning applications as condensers. Little study has been made in the application of microchannels in automotive heat exchangers, particularly the radiator. The presented research captures the need for the design improvement of radiator heat exchangers in heavy-duty vehicles in order to reduce aerodynamic drag and improve fuel economy. A method for analyzing an existing radiator is set forth including the needed parameters for effective comparisons of alternative designs. An investigation of microchannels was presented and it was determined that microchannels can improve the overall heat transfer of a radiator but this alone will not decrease the dimensions of the radiator. Investigations into improving the air-side heat transfer were considered and an improved fin design was found which allows a reduction in frontal area while maintaining heat transfer. The overall heat transfer of the design was improved from the original design by 7% well as 52% decrease in frontal area but at the cost of 300% increase in auxiliary power. The energy saved by a reduction in frontal area is not substantial enough to justify the increase of auxiliary power. The findings were verified through a computational fluid dynamic model to demonstrate the heat transfer and pressure drop of microchannel tubes. The results confirmed that heat transfer of microchannels does improve the thermal performance of the radiator but the pressure drop is such that the net benefit does not outweigh the operating cost. An additional CFD study of the new fin geometry and air-side heat transfer predictions was conducted. The results of the study confirmed the theoretical calculations for the fin geometry.
4
Leupin, Andreas. "Spectral emission and improvement of technical infrared radiators /". [S.l.] : [s.n.], 1989. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=8942.
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5
Juyal, Prateek. "Directive microstrip disc radiators based on TM1m modes". IEEE TAP, 2016. http://hdl.handle.net/1993/32074.
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Fundamental TM11 mode of circular microstrip antennas has a limitation of low broadside gain. This thesis explores and investigates the possibility of designing high gain circular microstrip antennas by using higher zeros of the first order mode, or the TM1m modes. Deficiencies in the existing methods of gain enhancement, motivates the need to look for new methods. This is done by first investigating the radiation characteristics of TM1m modes, and then providing techniques for sidelobe suppression in their radiation patterns. Several approaches are proposed and corresponding to each developed technique, an example of high gain antenna is designed, fabricated and experimentally evaluated.
First, through the radiation characteristics of a magnetic loop over an infinite ground plane, we explain the occurrence of high sidelobes in the E-plane radiation patterns of the TM1m modes. By noting the peak directivity and sidelobe variation with loop size, we propose, investigate and demonstrate the use of high permittivity substrates to reduce the sidelobes in the TM12 mode. Second, to remove the dependence of the radiation characteristics on high permittivity substrates, another technique to suppress the high sidelobes of TM12 mode, is presented. It is found that introducing a narrow nonresonant rectangular slot at the patch center, sidelobes of the TM12 mode can be effectively suppressed. Sidelobe level (SLL) suppression is demonstrated by both simulation and measurement, using various configurations.
Third, it is proposed that linearly superimposing the radiation fields of either odd or even zeros of the first order mode, can achieve both high gain and low sidelobes. To show this, stacked antenna configurations of TM11 and TM13 modes are thoroughly investigated and SLL suppression is demonstrated. Finally, to leverage further advantage of the linear superposition of modes, a single layer annular slot loaded antenna configuration is proposed.
The proposed new configurations are based on higher order TM1m modes, which, for excitation, requires electrically large conducting discs. This property offers one more advantage at high frequencies, where antenna size becomes too small for the fundamental mode to fabricate and feed. The proposed electrically large antennas eliminate these problems, and become more practical to fabricate.February 2017
6
Wu, Ziran. "Electromagnetic Crystal based Terahertz Thermal Radiators and Components". Diss., The University of Arizona, 2010. http://hdl.handle.net/10150/195207.
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This dissertation presents the investigation of thermal radiation from three-dimensional electromagnetic crystals (EMXT), as well as the development of a THz rapid prototyping fabrication technique and its application in THz EMXT components and micro-system fabrication and integration. First, it is proposed that thermal radiation from a 3-D EMXT would be greatly enhanced at the band gap edge frequency due to the redistribution of photon density of states (DOS) within the crystal. A THz thermal radiator could thus be built upon a THz EMXT by utilizing the exceptional emission peak(s) around its band gap frequency. The thermal radiation enhancement effects of various THz EMXT including both silicon and tungsten woodpile structures (WPS) and cubic photonic cavity (CPC) array are explored. The DOS of all three structures are calculated, and their thermal radiation intensities are predicted using Planck's Equation. These calculations show that the DOS of the silicon and tungsten WPS can be enhanced by a factor of 11.8 around 364 GHz and 2.6 around 406 GHz respectively, in comparison to the normal blackbody radiation at same frequencies. An enhancement factor of more than 100 is obtained in calculation from the CPC array. A silicon WPS with a band gap around 200 GHz has been designed and fabricated. Thermal emissivity of the silicon WPS sample is measured with a control blackbody as reference. And enhancements of the emission from the WPS over the control blackbody are observed at several frequencies quite consistent with the theoretical predictions. Second, the practical challenge of THz EMXT component and system fabrication is met by a THz rapid prototyping technique developed by us. Using this technique, the fabrications of several EMXTs with 3D electromagnetic band gaps in the 100-400 GHz range are demonstrated. Characterization of the samples via THz Time-domain Spectroscopy (THz-TDS) shows very good agreement with simulation, confirming the build accuracy of this prototyping approach. Third, an all-dielectric THz waveguide is designed, fabricated and characterized. The design is based on hollow-core EMXT waveguide, and the fabrication is implemented with the THz prototyping method. Characterization results of the waveguide power loss factor show good consistency with the simulation, and waveguide propagation loss as low as 0.03 dB/mm at 105 GHz is demonstrated. Several design parameters are also varied and their impacts on the waveguide performance investigated theoretically. Finally, a THz EMXT antenna based on expanding the defect radius of the EMXT waveguide to a horn shape is proposed and studied. The boresight directivity and main beam angular width of the optimized EMXT horn antenna is comparable with a copper horn antenna of the same dimensions at low frequencies, and much better than the copper horn at high frequencies. The EMXT antenna has been successfully fabricated via the same THz prototyping, and we believe this is the first time an EMXT antenna of this architecture is fabricated. Far-field measurement of the EMXT antenna radiation pattern is undergoing. Also, in order to integrate planar THz solid-state devices (especially source and detector) and THz samples under test with the potential THz micro-system fabricate-able by the prototyping approach, an EMXT waveguide-to-microstrip line transition structure is designed. The structure uses tapered solid dielectric waveguides on both ends to transit THz energy from the EMXT waveguide defect onto the microstrip line. Simulation of the transition structure in a back-to-back configuration yields about -15 dB insertion loss mainly due to the dielectric material loss. The coupling and radiation loss of the transition structure is estimated to be -2.115 dB. The fabrication and characterization of the transition system is currently underway. With all the above THz components realized in the future, integrated THz micro-systems manufactured by the same prototyping technique will be achieved, with low cost, high quality, self-sufficiency, and great customizability.
7
Boo, Joon-Hong. "Transient analysis of heat pipe radiators for space station applications". Diss., Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/19553.
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8
Mora, Akhil, i Raghavendra Machipeddi. "Development of Tool in MATLAB for the Durability Prediction of Radiators". Thesis, Blekinge Tekniska Högskola, Institutionen för maskinteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-15653.
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Durability is the most important factor in the design of heat-exchangers to meet the specifications of the customers. To predict the durability, endurance tests are carried out. In this thesis, one of the endurance tests, thermal cycling is performed for three different internal coolant flows until failure which is known as Wöhler test. A tool is developed in MATLAB that could import data from all kinds of endurance tests and visualizes time histories of every channel of the test (test parameters such as temperature, pressure, flow). An algorithm is developed for Level Crossing counting method which works based on the Markov cycle counting method. This produces Level crossing curves (LCC) for all the channels of the test which says how well a test has been performed and the total number of cycles of the test. It was observed that the LCCs obtained from the tool gives accurate results when compared with those obtained from LMS software whose approach of producing LCCs is Rainflow cycle counting method. Strain measurements are performed for the same flowrates as that of the Wöhler tests. The results from strain measurements and Wöhler tests are used in the determination of Basquin’s coefficient of the Wöhler curve. It was observed that the optimal value of Basquin’s coefficient is 3.4.
9
Gerova, Klementina. "Thermo-fluid effects associated with modelling subscale automotive heat exchangers". Thesis, Cranfield University, 2015. http://dspace.lib.cranfield.ac.uk/handle/1826/9875.
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Automotive components are tested extensively in wind tunnels by automotive manufacturers and race teams. This is usually achieved using an accurate scale model representation of the component within the wind tunnel. Automotive heat exchangers, however, are comprised of numerous intricate geometries and are therefore impractical to produce at model scale. Instead they are simply modelled as pressure drops, achieved using a thin mesh or honeycomb of known porosity. Most commercial computational fluid dynamics solvers ignore the geometry of the heat exchanger and instead model it as a discontinuity with a known pressure drop and heat transfer. The pressure drop across an automotive heat exchanger, however, was found to vary with both the coolant temperature and the angle of inclination of the heat exchanger. This thesis initially presents a relationship between the pressure drop coefficient and the inclination angle for varying media porosities. Mathematical relationships for inclination angles of 0°, 15°, 30° and 45°. were derived relating this pressure drop coefficient to the porosity of the media. Weighted least squares is proposed over ordinary least squares when obtaining the Forchheimer equation coefficients from experimental measurements. Investigation extends into the thermo-fluid effects on a full scale automotive heat exchanger when inclined at 0 °, 15°, 30° and 45°. It was found, depending on the angle, that there was a difference in the pressure drop of up to 10% between the unheated and heated (100 C) heat exchanger. Based on the proposed mathematical relationship, this correlated to a 4% decrease in porosity in order to accurately model the automotive heat exchanger at subscale. The thesis concludes with experimental and numerical investigation into the heat transfer on a hydrodynamically and thermally developing ow within a radiator channel. Laser doppler anemometry measurements recorded a 1.5% increase in the centreline velocity compared to 0.8% obtained from numerical simulation.
10
Myhren, Jonn Are. "Potential of Ventilation Radiators : Performance evaluation by numerical, analytical and experimental means". Doctoral thesis, KTH, Strömnings- och klimatteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-31813.
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Energy consumption for heating and ventilation of buildings is still in 2011considered far too high, but there are many ways to save energy and construct lowenergy buildings that have not been fully utilised. This doctoral thesis has focused onone of these - low temperature heating systems. Particular attention has been given tothe ventilation radiator adapted for exhaust-ventilated buildings because of itspotential as a low energy consuming, easily-operated, environmentally-friendlysystem that might also ensure occupant health and well-being. Investigations were based on Computational Fluid Dynamics (CFD) simulations andanalytical calculations, with laboratory experiments used for validation. Main conclusions: Low and very low temperature heating systems, such as floor heating, in general createan indoor climate with low air speeds and low temperature differences in the room, whichis beneficial for thermal comfort. A typical disadvantage, however, was found to beweakness in counteracting cold down-flow from ventilation air supply units in exhaustventilatedbuildings. with ventilation radiators, unlike most other low temperature systems, it was found thatthe risk of cold draught could be reduced while still maintaining a high ventilation rateeven in cold northern European winters. ventilation radiators were found to be more thermally efficient than traditional radiators. design of ventilation radiators could be further modified for improved thermal efficiency. at an outdoor temperature of -15 °C the most efficient models were able to give doublethe heat output of traditional radiators. Also, by substituting the most efficient ventilationradiators for traditional radiators operating at 55 °C supply water temperature, it wasfound that supply water temperature could be reduced to 35 °C while heat outputremained the same and comfort criteria were met. lowering the supply water temperature by 20 °C (as described above) could givecombined energy savings for heating and ventilation of 14-30 % in a system utilising aheat pump. supply water temperatures as low as 35 °C could increase potential for utilising lowtemperature heat sources such as sun-, ground-, water- or waste-heat. This would beparticularly relevant to new-built “green” energy-efficient buildings, but severaladvantages may apply to retrofit applications as well. Successful application of ventilation radiators requires understanding of relevant buildingfactors, and the appropriate number, positioning and size of radiators for best effect.Evaluation studies must be made at the level of the building as a whole, not just for theheating-ventilation system. This work demonstrated that increased use of well-designed ventilation radiatorarrangements can help to meet regulations issued in 2008 by the Swedish Departmentof Housing (Boverket BBR 16) and goals set in the Energy Performance of BuildingsDirective (EPBD) in the same year.QC 20110328
STEM Projektnummer:30326-1 Energieffektiva lågtemperatursystem i byggnader
11
Cooper, James Roger. "Novel wireless sensor configurations incorporating isotropic radiators on conformal artificial magnetic conductors". Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/52246.
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The objective of the presented research is to develop a novel, ink-jet printed, chipless, passive, wireless sensor topology, which can radiate in a near isotropic pattern without interference from embedded devices, for use in dispersed sensor networks. This objective includes the development of a hardware based, uniquely identifiable, collision avoidance communication method, and an integrated sensor system that is easily integrated into the topology.
Wireless sensor networks can be and are used in military, medical and industrial applications; and the demand for them is ever growing. However, current sensor networks have various trade-offs and limitations, including cost, number of distinguishable nodes, and ease of manufacturing. These trade-offs lead to unique sensors needing to be designed for each situation. To develop a widely used module, a topology must be developed that can meet as many demands as possible with fair tradeoffs.
Many of the above proposed criteria for the topology are already integrated into RFID technology. Therefore, much of the research is the application and advancement of current RFID technology for the purpose of designing the topology. The research begins with the theory and design of conformal artificial magnetic conductors, which is used in the design of a near isotropic radiator and isolated core for device embedding. Then, novel fabrication techniques will be investigated and deployed in the fabrication of the topology. Next, a novel "smart skin" sensor is developed which is easily integrated into the desired fabrication technique. Finally, an anti-collision RFID circuit for on-tag placement, which is based on frequency-doubling transceivers, is designed, which can also be easily integrated into the final topology.
This module is designed for use with a variety of different sensors. This versatility gives it ruggedness for use in many different environments. For proof of concept, this topology is fabricated and tested against current commercially sold tags.
Through the design and testing of the radiator, circuitry, and embedded sensors, it is shown that this design is a suitable topology for use in many different environments and applications.
12
Smith, Peter. "Moment method analysis of microstrip/stripline fed slot radiators including polarisation agility". Thesis, Heriot-Watt University, 1995. http://hdl.handle.net/10399/744.
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Larue, Mathis. "Simulation of the field generated by an array antenna with misplaced radiators". Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-278502.
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An array antenna is designed and commanded assuming a perfect positioning of the radiators. However, it is technically impossible to actually place each element in the exact position (mechanical, assembly errors and thermodynamic efforts), which generates errors in aim, amplitude and shape of the main beam while increasing the sidelobes. That’s why it is needed to take in account those phenomena while designing an array antenna, in particular the mechanical design of the supporting and positioning these elementary radiating elements.The tool developed in this work will be used to determine the acceptable manufacturing errors which will be the basis for specifying the mechanical design in terms of fabrication tolerances and thermomechanical deformation.
14
Brierley, Philip David. "Some practical applications of neural networks in the electricity industry". Thesis, Cranfield University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267333.
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15
Strickland, Peter C. (Peter Charles) Carleton University Dissertation Engineering Electrical. "Techniques for the synthesis of wideband, series-fed arrays of microstrip patch radiators". Ottawa, 1989.
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16
Wrighton, Jeffrey Michael. "Charge correlation effects in the broadening of spectral lines from highly charged radiators". [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0002280.
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17
Johnson, Dennis R. "Analysis and synthesis of radiative heat transfer in longitudinal fins in free space and non-free space". Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA236942.
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Thesis (M.S. in Astronautical Engineering)--Naval Postgraduate School, June 1990.Thesis Advisor(s): Kraus, Allan D. Second Reader: Brown, Sue. "June 1990." Description based on signature page. DTIC Identifier(s): Radiators (heating and cooling), radiative transfer, heat transfer (radiation). Author(s) subject terms: Radiative heat transfer, longitudinal fins, free space and non-free space. Includes bibliographical references (p. 147-148). Also available online.
18
Osz, Katalin. "Improvisatory home heating : the gap between intended and actual use of radiators and TRVs". Thesis, Loughborough University, 2016. https://dspace.lboro.ac.uk/2134/21742.
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Ongoing modification and change is core to how domestic and built environments function. Thus occupants domestication and development of home heating practices around low-carbon technologies is likely to exceed what building engineering sciences have the ability to plan ahead for. Yet, environmental policies and low -carbon industry approaches to sustainable energy consumption are characterised by a high degree of technological determinism. Disciplinary approaches to sustainable energy consumption tend to separate home heating into stable, routine interaction with control points, environmental factors and socio-demographic drivers. Framing low-carbon technical change in isolation from domestic environments often leads to a gap between intended and actual use of technologies. By focusing on TRVs (thermostatic radiators valve) and radiators, this thesis takes an interdisciplinary turn to jointly examine the social and environmental elements of households energy use. A turn to sensory ethnography and practice-place relationships offers a way to better understand how people use energy for space heating in relation to the buildings they live in and how improvisatory uses of technologies emerge from flows of material, domestic, sensory and physical contingencies of the home. Combining home video tours with building energy monitoring in eight homes, the thesis demonstrates that home heating is a place-event of the home because heating systems and energy consumption are woven into the fabric of everyday life. Environmental elements show that the social and technical are inseparable in energy used for space heating and individual elements imply that the domestication of technologies is highly unpredictable. The thesis synthesises findings into a taxonomy table of irregular radiator and TRV use. On the one hand, irregularities indicate that improvisatory uses of technologies are productive sources of sustainable change because they can be potential sites for co-design. On the other hand, the interwoven character of the social and technical in households energy use critically challenges how environmental policy, low-carbon industry and disciplinary approaches frame intervention into sustainable energy consumption. The thesis argues for the value of logic of intervention and sustainable change that is collaborative, system-focused and gradually uncovers interrelationships.
19
Hirayama, Y. "Heat and mass transfer regimes for room cooling and dehumidification using chilled water radiators". Thesis, Cranfield University, 1998. http://hdl.handle.net/1826/4028.
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The application of room radiators for the purposes of cooling and dehumidification in
buildings for hot and humid climates is investigated. The radiator is purposely brought
below the dew point temperature of the room air thereby creating condensation on the
radiator surface. The condensate is then collected at the base of the radiator and
removed. Mathematical models describing the heat transfer regime within a room when
this system is used have been verified using climate chamber tests. The models show
good agreement with the experimental results for radiator (a) with a height of 1 m, but
not as accurate for radiator (b) with a height of 2 m. The underestimation of the real
values by the convective heat transfer model used for the geometric construction of the
radiator tested is attributed to the effect of air entrainment along the height of the
radiator. Results indicate the importance of the radiant transfer component of the
radiator, as well as its effectiveness to remove latent heat. In view of improving thermal
comfort and energy efficiency, the implication of the results from this investigation of the
heat transfer characteristics of the radiator used for cooling and dehumidification is such
that the chilled radiator may offer a definite alternative to conventional air conditioning
systems. Partial or full matching of the sensible and latent component of the radiator
output to the load requirements of a building should prove particularly effective in hot
and humid regions where the latent heat factor of the total cooling load is high.
20
Brokaw, Wendell. "SOLUTION OF ELECTROMAGNETIC SCATTERING PARAMETERS AND RADIATION PATTERNS OF ARBITRARY BODY OF REVOLUTION RADIATORS". Doctoral diss., University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3546.
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A novel full wave analysis method to determine the scattering parameters and the radiation field intensities of arbitrary Body of Revolution (BOR) radiators consisting of impenetrable media is explored through derived components of modal analysis and the method of moments (MoM). Modal excitation is utilized to excite the structural feed; allowing for a more accurate measure of the scattering parameters of the total structure as opposed to the use of external excitation sources. The derivation of the mode matching method introduces a novel approach to achieving a frequency independent coupling matrix that will reduce the computational requirements for iterations utilized in the solution of multi-step discontinuous junctions. An application of interpolation functions across a single element of the MoM's traditional basis function approach allows for the ability to facilitate the meshing of complex structures. The combined field integral equation method is implemented in the analysis method to assure the mitigation of spurious solutions that can be problematic for electric field integral equation solutions that are predominant in many MoM based codes. The structures of interest represent bodies of revolution (BOR), which maintains that the structures must exhibit rotational symmetry about the longitudinal, or directional, axis. The complexity of the domain of structures that can be treated with the analysis method will be significantly reduced through the use of BOR symmetry of the structure. The proposed method for the solution of structures will include the comprehensive treatment of Boundary Value Problems (BVP's) through modal analysis, aperture treatment, and an application of the method of moments. Solutions for BOR radiating structures can be divided into two regions of analytical concern, the inner guided wave region and the outer radiating region. Modal analysis will be used to determine the scattering matrix of the inner guided wave region. The modal analysis will consist of subdividing the inner region into a number of finite step discontinuities, and the method of mode matching will be implemented to numerically solve the BVP's at each step discontinuity for a finite number of modal field distributions. The surface field equivalence principle will be applied to treat the aperture in order to produce an equivalent problem that supplants a source magnetic current density and an induced electric current density across the aperture that will radiate in the presence of the outer structural material of the BOR radiator. An algorithm utilizing the MoM is applied to solve integral equations that are defined to treat the surfaces of the BOR structure using electromagnetic boundary conditions. The application of the MoM will develop the field intensities on the aperture with complete consideration of the outer structural boundaries of the BOR radiator. The field intensities on the aperture will be related to the inner guided wave region through electromagnetic boundary conditions, and an admittance matrix will be numerically calculated. The admittance matrix will then apply to the inner guided wave region's scattering matrix to determine the reflection and transmission coefficients at the input of the BOR radiator. The comprehensive solution method will be applied to a variety of BOR structures; the electromagnetic solutions of the structures as obtained by the proposed method shall be verified for accuracy against comparative analysis of the structures using known computational packages that have been generally accepted throughout industry with respect to design capabilities.Ph.D.
Department of Electrical and Computer Engineering
Engineering and Computer Science
Electrical Engineering
21
Smith, Steven M. "The use of electrical transmission line theory to predict the performance of spacecraft radiators". Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/27324.
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The cascade algorithm that is used for extended surface analysis depends on a new parameterization called the thermal transmission matrix to represent a single fin. This thermal transmission matrix, which is intended to replace the more familiar fin efficiency as a design and analysis parameterization, is a linear transformation that maps conditions of heat flow and temperature at the fin tip to heat flow and temperature conditions at the fin base. The cascade algorithm was derived by resorting to an analogy between a fin and the electrical transmission line. The cascade algorithm permits a fin to be subdivided into many subfins each having a thermal transmission matrix and then the individual transmission matrices for each of the subfins can be used, via a simple matrix product to form an overall equivalent thermal transmission matrix for the entire fin. This thesis develops a thermal transmission matrix for the radiating rectangular, trapezoidal, and triangular fins both for the free space and non-free space environments. Test cases have been run and their solutions exactly match those contained in the literature. The thesis concludes with optimization studies for Thermal Transmission Matrix, Cascade Algorithm, Extended Surface, Cooling Fin, Radiative Fin, Longitudinal Fin, Rectangular Fin, Trapezoidal Fin, Triangular Fin, Optimum
22
Tait, Jan. "An electro-optic measurement system for electric fields near RF and microwave radiators and scatterers". Thesis, Stellenbosch : Stellenbosch University, 2000. http://hdl.handle.net/10019.1/51596.
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Thesis (MScEng)--University of Stellenbosch, 2000.ENGLISH ABSTRACT: An electro-optic sensor system was developed which uses the modulated scatterer technique [1] to measure the fine structure-amplitude and phase-of electric fields with the minimum of perturbation. The theory for the technique is discussed in detail, with the Lorentz Reciprocity theorem as foundation. The system is also treated as a general two port and solved in terms of the impedances present. This comprises self impedances and mutual impedances. The signals scattered by the dipole scatterer are modeled as amplitude modulated signals and a detailed detection scheme is presented. The detection of the signals is done by a digital correlation process. This is quite similar to synchronous detection. A detailed sensitivity analysis is presented that was used to determine the quality of the system. This analysis is backed by a practical sensitivity measurement. A few antennas and scatterers are measured in the X-band using the system, and results are compared with theory. These systems include a pyramidal horn, an E-plane sectoral horn and a simple waveguide. Half plane diffraction by a metal sheet is also presented. The practical implementation of the theory is emphasized.
AFRIKAANSE OPSOMMING: 'n Elektro-optiese meetsisteem is ontwikkel wat die gemoduleerde strooier tegniek [11 gebruik om die fyn struktuur-amplitude en fase-van elektriese velde te meet. Hierdie tegniek versteur die velde minimaal. 'n Volledige ondersoek word gedoen na die teorie van die stelsel. Die basis van die metode Ie in die Lorentz Resiprook teorie. Alhoewcl daar gekonsentreer word op hierdie teorie, is die stelsel ook beskou as 'n tweepoort. Die wedersydse en ei impedansies van die verskillende komponente word gebruik om die velde op te los. Die gestrooide seine, as gevolg van die dipool strooier, word gemodelleer met b hulp van amplitude modulasie. Die deteksie van hierdie seine word deeglik bespreek. In plaas van 'n analoogstelsel, word 'n digitale korrellasie proses gebruik om die velde te meet. Di sensitiwiteit van die stelsel word geanaliseer. Verder word metings met di stelsel gen em om die teoretiese analise te staaf. 'n Paar X-band sisteme word gebruik om metings te neem. Hicrdi metings word ook vergelyk met teor ti se resultate. Stelsels wat gemeet is sluit die volgencle in: 'n piramidale horing antenna, 'n E-vlak sektorale horing antenna, 'n X-band golfgeleier en die diffraksi op die rand van 'n plaat. Die praktiese implemcntering van die teorie word beklemtoon.
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Gbele, Kokou. "Fabrication of Novel Structures to Enhance the Performance of Microwave, Millimeter Wave and Optical Radiators". Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/612886.
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This dissertation has three parts which are distinctive from the perspective of their frequency regime of operation and from the nature of their contributions to the science and engineering communities. The first part describes work that was conducted on a vertical-external-cavity surface emitting-laser (VECSEL) in the optical frequency regime. We designed, fabricated, and tested a hybrid distributed Bragg reflector (DBR) mirror for a VECSEL sub-cavity operating at the laser emission wavelength of 1057 nm. The DBR mirror was terminated with a highly reflecting gold surface and integrated with an engineered pattern of titanium. This hybrid mirror achieved a reduction in half of the number of DBR layer pairs in comparison to a previously reported, successful VECSEL chip. Moreover, the output power of our VECSEL chip was measured to be beyond 4.0Wwith an optical-to-optical efficiency of 19.4%. Excellent power output stability was demonstrated; a steady 1.0 W output at 15.0 W pump power was measured for over an hour. The second part reports on an ultrafast in situ pump-probing of the nonequlibrium dynamics of the gain medium of a VECSEL under mode-locked conditions. We proposed and successfully tested a novel approach to measure the response of the inverted carriers in the active region of a VECSEL device while it was operating under passively mode-locked conditions. We employed the dual-frequency-comb spectroscopy (DFCS) technique using an asynchronous optical sampling (ASOPS) method based on modified time-domain spectroscopy (TDS) to measure the nonequilibrium dynamics of the gain medium of a phase-locked VECSEL that we designed and fabricated to operate at the1030 nm emission wavelength. Our spectroscopic studies used a probe pulse of 100 fs and an in situ pump pulse of 13 ps. We probed the gain medium of the VECSEL and recorded a depletion time of 13 ps, a fast recovery period of 17 ps, and 110 ps for the slow recovery time. Our scans thus demonstrated a 140 ps full depletion-recovery cycle in the nonequilibrium state. The third part discusses work in the microwave and millimeter wave frequency regimes. A new method to fabricate Luneburg lenses was proposed and demonstrated. This type of lens is well known; it is versatile and has been used for many applications, including high power radars, satellite communications, and remote sensing systems. Because the fabrication of such a lens requires intricate and time consuming processes, we demonstrated the design, fabrication and testing of a Luneburg lens prototype using a 3-D printing rapid prototyping technique both at the X and Ka-V frequency bands. The measured results were in very good agreement with their simulated values. The fabricated X-band lens had a 12 cm diameter and produced a beam having a maximum gain of 20 dB and a beam directivity (half-power beam width (HPBW)) ranging from 12° to 19°). The corresponding Ka-V band lens had a 7 cm diameter; it produced a beam with a HPBW about the same as the X-band lens, but with a maximum gain of more than 20 dB.
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Puzella, Angelo. "Theoretical and Experimental Development of an Array of Droopy Bowties with Integrated Baluns". Digital WPI, 2014. https://digitalcommons.wpi.edu/etd-dissertations/313.
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"Theoretical modeling, design, assembly, and measurement of a novel integrated phased array radiator are presented. The droopy bowtie turnstile radiator with quad line feed meets challenging radar requirements and uses low cost manufacturing and assembly techniques. This thesis develops the complete theoretical model (antenna, balun, feeding network) of a broadband phased array radiator: the droopy bowtie turnstile radiator. A novel quad line balun feed is developed that provides a low loss, high isolation, and coincident phase-center feeding network for the droopy bowtie. The radiator and feed design combines broadband RF performance and high-isolation dual-linear polarization in a low profile, compact package that enables wide scan volume performance versus frequency. This thesis develops low-cost manufacturing and assembly techniques applied to the droopy bowtie radiator with the quad line feed. The new radiator design would utilize low cost fabrication techniques such as injection molding and 3-D printing, and also leverages automated assembly techniques. Measurement prototypes and array prototypes of droopy bowtie radiators with the quad line feed are developed for L- and X-bands. The measurements demonstrate broadband RF performance in a low profile compact package viable for wide-scale phased array applications."
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Ziolkowski, Richard W. "Passive and active metamaterial-inspired nano-scale antennas". IEEE, 2016. http://hdl.handle.net/10150/623141.
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A variety of open and closed multi-layered nanoparticle structures have been considered analytically and numerically for their use as scatterers and radiators. These include metamaterial-inspired structures based on dielectrics and metals excited by either plane waves or electric Hertzian dipoles at optical frequencies. Both passive and active (gain impregnated dielectric) materials have been considered. Enhanced and mitigated scattering and radiating effects have been modeled. Nano-antenna and nano-amplifier configurations for optical applications have been emphasized. A review of these modeling efforts will be presented.
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Schlub, Robert Walter, i n/a. "Practical Realization of Switched and Adaptive Parasitic Monopole Radiating Structures". Griffith University. School of Microelectronic Engineering, 2004. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20040610.112148.
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Switched and adaptive parasitic monopole array radiating structures are investigated. Antenna design is orientated toward increasing practicability for implementation in terrestrial wireless communication systems. A number of antennas are designed with the aid of optimization and commercial simulation software. Simulation procedure was verified with the experimental manufacture and measurement of the arrays. The antennas presented in this thesis comprise an active monopole surrounded by a ring of parasitic monopoles. Parasitic radiators are constructed with static loading to enable simple experimental realization. Beam positions of an electrically steered equivalent antenna are thus simulated. Antenna symmetry ensures the beam can be reproduced throughout the azimuth. Complex antenna geometries require antenna design through optimization. A genetic algorithm is employed with HFSS and NEC for electromagnetic analysis. The robust optimization method couples with simulation software flexibility to provide an effective design tool for arbitrary structures. The genetic algorithm is employed strictly for design and not complete structural optimization. Dual band, five and six element switched parasitic antennas are presented. Lumped elemental loading along the radiators provide resonance and directed radiation at two GSM frequencies. Load value, radiator dimension and spacing are incorporated as design parameters. Experimentally built, 10dB return loss bandwidths of 17.2% and 9.6% and front to back ratios of 12.6dB and 8.4dB at 900MHz and 1900MHz respectively are measured. To reduce the ground requirements of monopole arrays, a skirted ground structure for switched parasitic antennas is analyzed. A six element switched parasitic monopole array with conductive ground skirt exhibits a front to back ratio of 10.7dB and main lobe gain of 6.4dBi at 1.575GHz. Radiation is not elevated despite lateral ground terminating at the parasitic elements. Skirt height is observed to linearly control radiation elevation, depressing the principal lobe through 40 degrees from 23 degrees above the horizontal. The Electronically Steerable Passive Array Radiator or ESPAR antenna is an adaptive parasitic monopole array. An ESPAR radiating structure incorporating a conductive ground skirt is designed for operation at 2.4GHz. Utility is confirmed with a frequency sensitivity analysis showing consistent electrical characteristics over an 8.1% bandwidth. The antenna design is improved with optimization to reduce average principal lobe elevation from 25 degrees to 9.7 degrees.
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Schlub, Robert Walter. "Practical Realization of Switched and Adaptive Parasitic Monopole Radiating Structures". Thesis, Griffith University, 2004. http://hdl.handle.net/10072/366803.
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Switched and adaptive parasitic monopole array radiating structures are investigated.
Antenna design is orientated toward increasing practicability for implementation in terrestrial wireless communication systems. A number of antennas are designed with the aid of optimization and commercial simulation software. Simulation procedure was verified with the experimental manufacture and measurement of the arrays. The antennas presented in this thesis comprise an active monopole surrounded by a ring of parasitic monopoles. Parasitic radiators are constructed with static loading to enable simple experimental realization. Beam positions of an electrically steered equivalent antenna are thus simulated. Antenna symmetry ensures the beam can be reproduced throughout the azimuth. Complex antenna geometries require antenna design through optimization. A genetic algorithm is employed with HFSS and NEC for electromagnetic analysis. The robust optimization method couples with simulation software flexibility to provide an effective design tool for arbitrary structures. The genetic algorithm is employed strictly for design and not complete structural optimization. Dual band, five and six element switched parasitic antennas are presented. Lumped elemental loading along the radiators provide resonance and directed radiation at two GSM frequencies. Load value, radiator dimension and spacing are incorporated as design parameters. Experimentally built, 10dB return loss bandwidths of 17.2% and 9.6% and front to back ratios of 12.6dB and 8.4dB at 900MHz and 1900MHz respectively are measured. To reduce the ground requirements of monopole arrays, a skirted ground structure for switched parasitic antennas is analyzed. A six element switched parasitic monopole array with conductive ground skirt exhibits a front to back ratio of 10.7dB and main lobe gain of 6.4dBi at 1.575GHz. Radiation is not elevated despite lateral ground terminating at the parasitic elements. Skirt height is observed to linearly control radiation elevation, depressing the principal lobe through 40 degrees from 23 degrees above the horizontal. The Electronically Steerable Passive Array Radiator or ESPAR antenna is an adaptive parasitic monopole array. An ESPAR radiating structure incorporating a conductive ground skirt is designed for operation at 2.4GHz. Utility is confirmed with a frequency sensitivity analysis showing consistent electrical characteristics over an 8.1% bandwidth. The antenna design is improved with optimization to reduce average principal lobe elevation from 25 degrees to 9.7 degrees.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Microelectronic Engineering
Full Text
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Bottau, Francesco. "Design and optimization af a race car cooling system". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
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The aim of this thesis is the design and the optimization of water radiator for the Tatuus F3 race car.
Tatuus is a racing car manufacturer which designs, produces and sells cars for different racing categories.
In a race car is essential that weight and occupied volume are kept as low as possible. This requirement is achieved by optimizing the vehicle’s components. For this reason, Tatuus commissioned a project focused on the optimization of heat exchangers. It is very important that the flow inside every radiator is as uniform as possible, to make it works in the most efficient way. With this respect, if in some channels the flow-rate is low or nil, they do not contribute to
the cooling process, hence represent a waste of space and weight.
To avoid this, it is crucial that inlet and outlet collectors have a shape such that the flow is distributed
almost uniformly inside each channel. This optimization can be obtained simulating different radiator configuration with CFD software and analyzing the internal flow distribution.
Using simulation solutions, it was possible to design radiators that guarantee a sufficiently uniform
flow.
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ALVES, RODRIGO M. "Segurança alimentar através da determinação de 2-alcilciclobutanonas em alimentos processados por radiação ionizante". reponame:Repositório Institucional do IPEN, 2016. http://repositorio.ipen.br:8080/xmlui/handle/123456789/26942.
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No. of bitstreams: 0Made available in DSpace on 2016-12-22T12:14:15Z (GMT). No. of bitstreams: 0
A irradiação de alimentos é um meio de preservação de alimentos onde se utiliza uma técnica de processamento que expõe os alimentos a uma radiação ionizante controlada de alta energia. O tratamento realizado com o uso das radiações ionizantes em alimentos tem muitas aplicações tecnologicamente e tecnicamente viáveis incluindo a capacidade de melhorar a segurança microbiológica, reduzir os níveis de bactérias patogénicas, inibir a germinação de tubérculos, aplicação fitossanitária, conservar alimentos armazenados ou a estabilidade de armazenamento e também é utilizada para aumentar a vida de prateleira de determinados produtos devido à redução da contaminação por microrganismos. Em função do aumento do comércio internacional de alimentos e das crescentes exigências regulatórias dos mercados consumidores, cada vez mais países importadores e exportadores têm demonstrando interesse na irradiação de alimentos e desenvolvido pesquisas na aplicação prática desta tecnologia e de métodos de detecção do tratamento. Inúmeras pesquisas foram realizadas mundialmente, resultando em eficientes protocolos para identificar quais alimentos foram ou não irradiados. Até então, o \"mito\" que alimentos irradiados não poderiam ser detectados e que não eram formados quaisquer produtos únicos da radiação foi substituído pelo conhecimento que muitas mudanças podem ocorrer nos alimentos irradiados e essas mudanças poderiam ser utilizadas como ferramentas para identificar essa tecnologia. O processamento por radiação resulta em formações de padrões característicos de hidrocarbonetos saturados, aldeídos, metil e etil ésteres e 2-alcilciclobutanonas, dependendo da composição do ácido graxo do lipídio que compõe o alimento. Com isso a proposta do trabalho foi levantar dados para comparar os efeitos das diferentes doses de radiação gama e de elétrons em alimentos que possuem gordura para verificar as possíveis alterações decorrentes do uso da irradiação, como a presença de 2-Alcilciclobutanonas e também, mostrar os principais equipamentos utilizados para a irradiação de alimentos e suas categorias, com o objetivo de informar o publico em geral.
Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
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Skřivánek, Michal. "Ocenění podniku LIPOVICA trade s.r.o". Master's thesis, Vysoká škola ekonomická v Praze, 2008. http://www.nusl.cz/ntk/nusl-15902.
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Business valuation of micro trading company LIPOVICA trade s.r.o; main business activity of the company is selling and distribution of aluminum radiators on the markets in the Czech and Slovak republic. The valuation is based on discounted cash flows method, economic value added method, capitalization of profits method and simple liquidation method.
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Akrman, David. "Optimalizace topné soustavy v bytovém domě". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-371822.
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This thesis solves hydraulic regulation existing heating system apartment building. It is a building of eight floors with dimensions of 21.0 x 26.0 m. The system se-amlessly heats the entire building residential building. Heating is the most original apartment, dealt with cast iron radiators. The heat source is CZT. The theoretical part is focused on the revitalization of heating systems.
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Ng, Eton Yat-Tuen, i eton_ng@hotmail com. "Vehicle engine cooling systems: assessment and improvement of wind-tunnel based evaluation methods". RMIT University. Aerospace, Mechanical and Manufacturing Engineering, 2002. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080422.100014.
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The high complexity of vehicle front-end design, arising from considerations of aerodynamics, safety and styling, causes the airflow velocity profile at the radiator face to be highly distorted, leading to potentially reduced airflow volume for heat dissipation. A flow visualisation study showed that the bumper bar significantly influenced the cooling airflow, leading to three-dimensional vortices in its wake and generating an area of relatively low velocity across at least one third of the radiator core. Since repeatability and accuracy of on-road testing are prejudiced by weather conditions, wind-tunnel testing is often preferred to solve cooling airflow problems. However, there are constraints that limit the accuracy of reproducing on-road cooling performance from wind-tunnel simulations. These constraints included inability to simulate atmospheric conditions, limited tunnel test section sizes (blockage effects) and lack of ground effect simulations. The work presented in this thesis involved use of on-road and wind-tunnel tests to investigate the effects of most common constraints present in wind tunnels on accuracy of the simulations of engine cooling performance and radiator airflow profiles. To aid this investigation, an experimental technique for quantifying radiator airflow velocity distribution and an analytical model for predicting the heat dissipation rate of a radiator were developed. A four-hole dynamic pressure probe (TFI Cobra probe) was also used to document flow fields in proximity to a section of radiator core in a wind tunnel in order to investigate the effect of airflow maldistribution on radiator heat-transfer performance. In order to cope with the inability to simulate ambient temperature, the technique of Specific Dissipation (SD) was used, which had previously been shown to overcome this problem.
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Rybář, Jakub. "Sálavé vytápění průmyslových hal". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2012. http://www.nusl.cz/ntk/nusl-225568.
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Indoor climate of industrial halls is now advantageously shaped radiant heating systems, which are more flexible and efficient than convection systems. The crucial component of indoor climate in these systems mean radiant temperature. The work focuses on theoretical and experimental research on the location and operation of radiant panels. For the theoretical part is used new computer software able to calculate the Institute TZB mean radiation temperature distribution in 2D space. The experimental part was carried out comprehensive measurements of indoor climate parameters specific industrial halls and subsequently compared. Work includes the design and comparison of three variants of heating in the indoor facility.
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Bowen, Mary Elizabeth. "Family Album". ScholarWorks@UNO, 2009. http://scholarworks.uno.edu/td/909.
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Ladomérská, Jana. "Vytápění objektu zdroji na různé druhy paliv". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227584.
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In my final thesis I am processing a proposal for heating and preparing hot water for a restaurant with accommodation. This is a three-storey brick house. It is situated on the territory of the Ústí region. The aim of my work is to propose and to assess the appropriate heat source for this object. In the object I chose heating radiators. The proposal is processed in two variants. In the first variant, I suggest a cascade of condensing boilers using as a source of heat. In the second variant, I suggest a cascade of electrical boilers. Hot water will be prepared in reservoir of warm water. The source of hot water will be the same as the source for heating.
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Sorge, Wolfram. "Beitrag zur Entwicklung von Störstrahlungstests im Nahfeld großer Prüflinge". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-27018.
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In dieser Arbeit wird das Verhalten der Störstrahlung großer Prüflinge untersucht mit dem Ziel, vorhandene Standards für Störstrahlungstests wie CISPR 16 zu verbessern. Diese Arbeit sieht als Standardtestumgebung einen reflektierenden, ausgedehnten Grund vor, auf dem sich der Prüfling befindet. Die Strahlung, die dieser aussendet, wird durch die Verteilung der elektrischen Feldstärke auf einer Testhalbkugel oberhalb des Grunds bewertet. Ihr Zentrum befindet sich am Fußpunkt des Prüflings. Eine solche Halbkugel stellt nahezu gleiche Abstände von etwa der Länge des Kugelradius' zwischen dem Prüfling und den auf ihr definierten Meßpunkten her. Da die Halbkugel geschlossen ist, kann auf ihr das gesamte vom Prüfling nach außen gestrahlte Feld nachgewiesen werden. Meßabstände mit in Normen vorgegebenen Längen sind in der Praxis nicht immer einzuhalten, vor allem dann, wenn sich Prüflinge in einer normalen Betriebsumgebung befinden. In beengten Umgebungen ist es hilfreich, Meßabstände zu verkürzen. Hieraus ergibt sich eine kleinere Testhalbkugel, die sich leichter abtasten läßt. Bei kurzen Meßabständen jedoch können Meßsonden in das Nahfeld des Prüflings ragen. Für diesen Fall werden in dieser Arbeit Feldeigenschaften in Prüflingsnähe untersucht. Aus denen ergeben sich Mindestabstände zum Prüfling, jenseits derer sich gemessene Feldstärkewerte zu größeren, in Normen vorgegebenen Abständen extrapolieren lassen. Um die Verteilung der Feldstärke auf einer Testfläche zu beschreiben, wird der Begriff der Halbwertsfläche eingeführt: Die Halbwertsfläche definiert jenen Teil der Testfläche, auf dem die Dichte der abgestrahlten Leistung mindestens die Hälfte ihres Maximums beträgt. Die Halbwertsfläche ergibt sich aus der Richtwirkung des Prüflings als Strahler. Sie ist somit ein Maß für die Wahrscheinlichkeit, auf der Testfläche das Strahlungsmaximum zu finden. Aus der Größe der Halbwertsfläche ergibt sich die nötige Anzahl an gleichmäßig auf der Testfläche verteilten Meßpunkten, um das Strahlungsmaximum mit gegebener Wahrscheinlichkeit zu finden. Wird an den Meßpunkten die Größe der Feldstärke berücksichtigt, läßt sich die Anzahl der Meßpunkte optimieren und das Vertrauen in den Test erhöhen. Als ein erster Schritt zur Entwicklung einer praktikablen Strahlungstestmethode wird die Testdrahtmethode untersucht. Bei dieser Methode wird Strahlung mit einem langen, um den Prüfling herum gespannten Draht erfaßt. Die Strahlung induziert in dem Draht einen Strom, der an den Drahtabschlüssen gemessen werden kann. Weil der Draht i. allg. lang ist, ist er sehr meßempfindlich. Ist er jedoch länger als eine Wellenlänge des abgestrahlten Felds, sind sein Übertragungsfaktor und damit die Meßergebnisse schwer zu bestimmen. Statistische Methoden der Auswertung werden hierzu untersucht. Ein System aus kleinen Meßsonden kann denselben Teil des Prüflings abdecken wie ein Testdraht. Weil als Übertragungsfaktor eines solchen Systems der einer Einzelsonde wirksam ist, lassen sich Ergebnisse aus Messungen mit einem solchen System leichter auswerten. Jedoch ist die Empfindlichkeit kleiner Sonden i. allg. gering. Der Weg zu einer praktischen Anwendung führt somit vorerst in die Richtung herkömmlicher Meßantennen, die in einem beweglichen System geeignete Testflächen abtasten. - (Die Dissertation ist veröffentlicht im Jörg Vogt Verlag, Dresden, Deutschland, http://www.vogtverlag.de, ISBN: 978-3-938860-25-0)In this work the behavior of radiation emitted by large equipment is investigated. The aim of investigation is to improve existing standardized radiation tests. The radiation from an EUT (equipment under test) placed on reflecting ground is described by the distribution of the electric field strength on a hemispheric test area, which encloses the EUT placed in its center. This kind of area guarantees a nearly equal measurement distance to the EUT from every point defined on it. This distance is defined by the radius of the hemisphere. However, measurement distances according to standards are difficult to realize. Because of practical constraints shorter distances will become useful. This requires a smaller test area, to be scanned more easily. At shorter measurement distances field probes are possibly located in the near field of the EUT. Therefore this work investigates the behavior of the field in the vicinity of the EUT to find an adequate transition point, beyond which, field strength values can be extrapolated to distances instructed by standards with confident results. An important parameter of the field strength distribution is the half-power area. It defines that part of the test area where the radiated power exceeds the half of its maximum. The half-power area is related to the directivity of the EUT, which can be approximated by antenna theory or statistics. If the directivity of the EUT is high, the half-power area is small, and the probability to find the field maximum on the test area is low. The size of the half-power area yields to a least number of observation points, equally distributed on the test area, to find the field maximum with a high level of confidence. If the field strength measured at any observation point is considered, the distance to other observation points can be optimized, and the level of confidence in the test can be increased. As a first step in developing a practicable field scanning method is highlighted: the test wire method. This method establishes a measurement executed by a long wire which covers the EUT. At its terminations current can be measured induced by the radiation. Because the wire is long it is very sensitive. However, if it is longer than one wave length of the radiation, the evaluation of results is difficult because of an uncertain transmission factor. Therefore, some statistic methods are applied to describe the behavior of results and their maxima. Also a system of small probes, e. g. short dipoles, can cover the same part of the EUT as a test wire. The measurement with small probes can be evaluated more easily because of a unique transmission factor. However, their sensitivity is lower
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Aygün, Munzur, i Kristian Henriques. "Tilluftsradiatorers påverkan på inomhusklimatet". Thesis, Malmö högskola, Fakulteten för teknik och samhälle (TS), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-20644.
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I dagens Sverige spenderar människor allt mer tid inomhus. Stadsborna tillbringar den mesta av sin tid inomhus, dvs. ca 90 %. Med detta räknas all den tid personerna vistas i hemmet och arbetet. Att människor spenderar så mycket av sin tid inomhus gör att inomhusklimatet blir en påverkande samt viktig faktor i vardagen (Nationalencyklopedin A). Syftet med studien är att undersöka upplevda problem med inomhusklimatet i två olika studentlägenheter som har tilluftsradiatorer. Med hjälp av frågeställningarna kommer problemen identifieras och slutligen som mål komma fram till olika förslag på lösningar. Metoden för att genomföra studien kommer att ske med hjälp av enkätundersökningar i två olika studentbostads fastigheter och där frågor besvaras gällande hur de boende upplever inomhusklimatet. Dessa svar jämförs sedan med varandra för att konstatera hur de skiljer sig åt och vad skillnaderna kan bero på. Resultatet visar att de boende i Rönnens studentbostäder upplever mest problem. Fastigheten består till största del av mindre lägenheter. Sommarstaden som är den andra fastigheten som har undersökts, domineras av större lägenheter. De boende på Sommarstaden upplever mindre besvär. Detta samband kan bero på lägenheternas storlek eller att tilluftsradiatorerna skiljer sig åt mellan de två fastigheterna. Av resultatet framkommer det att båda fastigheter har brister när det kommer till problem med kall inomhustemperatur. För att förbättra bristerna bör information ges till ny inflyttande hyresgäster angående hur möblering bör gå till med vistelsezon i åtanke. Resultatet har visat att det finns skillnader mellan fastigheternas tilluftsradiatorer. Även då Sommarstadens tilluftsradiator kan anses vara av den bättre modellen så är denna inte tillräckligt bra eftersom en stor del av de boende upplever en för kall inomhustemperatur.In todays Sweden people spend a lot of time indoors. People living in cities spend about 90% of their time indoors; this includes all the time spent both at home and at work. That amount of time spent indoors means that the indoor climate becomes an important as well as an influential part of everyday life. (NE A). The purpose of this study is to examine the perceived problems with the indoor climate in student apartments that have ventilation radiators. With the help of the queries we identify these problems and ultimately aim to come up with proposals for different solutions. The method for implementing the study will be done with the help of questionnaires in two different student-housing properties, where questions are answered regarding how residents perceive the indoor climate. These responses are then compared with each other to ascertain how they differ and why. The results show that the residents of the Rönnen student housing experience the most problems. This property consists largely of small apartments. Larger apartments dominate Sommarstaden, which is the other surveyed property. The residents of Sommarstaden are experiencing minor inconvenience. These problems may depend on the size of the apartments and/or ventilation radiators that differ between the two properties. Through the results it is apparent that both properties have flaws regarding indoor temperature. In order to improve these flaws information regarding furnishing in an occupied zone should be given to the new occupants. Results show that the ventilation radiators differ between the two properties. Although the ventilation radiators in Sommarstaden could be seen as the better model of the two presented, occupants still feel that the indoor temperature is to cold.
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Molnár, Lukáš. "Vytápění bytového komplexu". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265562.
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The aim of the diploma thesis is to design heating and hot water preparation in a complex of buildings consisting of retail space and two residential buildings. Retail space is heated using VRF system and apartment blocks are heated by gas boilers located in the mechanical room in the basement. Gas boilers are connected to heating system and storage water he-ater. The heating surface is created by tabular and tubular heating units. Heat consumption in apartments is measured by calorimeters with remote data collection system. The temperatu-re in each flat is controlled by an electrically powered zone valve.
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Sanz, Aceituno Angel Luis. "Control algorithms for energy savings in irregularly occupied buildings". Thesis, Högskolan i Gävle, Avdelningen för bygg- energi- och miljöteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-15155.
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The Heating, Ventilation and Air Conditioning (HVAC) systems are nowadays in almost every new building, develop or improve better control strategies for them is very common, looking to have more energy efficiency and require less input parameters from the user. In this project, new control strategies based in previous theory models has been used with a new approach in order to find a good solution for irregular occupied spaces. In this new approach a feed-forward filter with a fixed preheating time, using an algorithm based on an identified model, calculates how much degrees the temperature room can be decreased and regulate the power of the radiators to do it.The results of this project displays that the chosen model have to be changed but the idea is interesting, because the simulations of the reference building give, with a preheating timeof 2 hours, around 3ºC of temperature reduction during 18 days and savings of 33% of the heat energy needed for the whole month.Considering that buildings and the residential sector currently account for 40 percent of Sweden's energy consumption and around 25 percent of other countries like USA or Spain, and that irregular spaces are more or less a 10% of the governmental, institutional, academic or public buildings, the potential savings are not negligible. The evaluation of this control strategy with its mathematical model as well as its resultsduring the month of January and the behavior of the system along the year have been made with the help of IDA program for simulation of the reference building and its energy system.
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Sorge, Wolfram. "Beitrag zur Entwicklung von Störstrahlungstests im Nahfeld großer Prüflinge". Doctoral thesis, Technische Universität Dresden, 2008. https://tud.qucosa.de/id/qucosa%3A25231.
Pełny tekst źródłaStreszczenie:
In dieser Arbeit wird das Verhalten der Störstrahlung großer Prüflinge untersucht mit dem
Ziel, vorhandene Standards für Störstrahlungstests wie CISPR 16 zu verbessern.
Diese Arbeit sieht als Standardtestumgebung einen reflektierenden, ausgedehnten Grund
vor, auf dem sich der Prüfling befindet. Die Strahlung, die dieser aussendet, wird durch
die Verteilung der elektrischen Feldstärke auf einer Testhalbkugel oberhalb des Grunds bewertet.
Ihr Zentrum befindet sich am Fußpunkt des Prüflings. Eine solche Halbkugel stellt
nahezu gleiche Abstände von etwa der Länge des Kugelradius' zwischen dem Prüfling und
den auf ihr definierten Meßpunkten her. Da die Halbkugel geschlossen ist, kann auf ihr das
gesamte vom Prüfling nach außen gestrahlte Feld nachgewiesen werden.
Meßabstände mit in Normen vorgegebenen Längen sind in der Praxis nicht immer einzuhalten,
vor allem dann, wenn sich Prüflinge in einer normalen Betriebsumgebung befinden.
In beengten Umgebungen ist es hilfreich, Meßabstände zu verkürzen. Hieraus ergibt sich
eine kleinere Testhalbkugel, die sich leichter abtasten läßt.
Bei kurzen Meßabständen jedoch können Meßsonden in das Nahfeld des Prüflings ragen.
Für diesen Fall werden in dieser Arbeit Feldeigenschaften in Prüflingsnähe untersucht. Aus
denen ergeben sich Mindestabstände zum Prüfling, jenseits derer sich gemessene Feldstärkewerte
zu größeren, in Normen vorgegebenen Abständen extrapolieren lassen.
Um die Verteilung der Feldstärke auf einer Testfläche zu beschreiben, wird der Begriff der
Halbwertsfläche eingeführt: Die Halbwertsfläche definiert jenen Teil der Testfläche, auf dem
die Dichte der abgestrahlten Leistung mindestens die Hälfte ihres Maximums beträgt. Die
Halbwertsfläche ergibt sich aus der Richtwirkung des Prüflings als Strahler. Sie ist somit
ein Maß für die Wahrscheinlichkeit, auf der Testfläche das Strahlungsmaximum zu finden.
Aus der Größe der Halbwertsfläche ergibt sich die nötige Anzahl an gleichmäßig auf der
Testfläche verteilten Meßpunkten, um das Strahlungsmaximum mit gegebener Wahrscheinlichkeit
zu finden. Wird an den Meßpunkten die Größe der Feldstärke berücksichtigt, läßt
sich die Anzahl der Meßpunkte optimieren und das Vertrauen in den Test erhöhen.
Als ein erster Schritt zur Entwicklung einer praktikablen Strahlungstestmethode wird die
Testdrahtmethode untersucht. Bei dieser Methode wird Strahlung mit einem langen, um
den Prüfling herum gespannten Draht erfaßt. Die Strahlung induziert in dem Draht einen
Strom, der an den Drahtabschlüssen gemessen werden kann. Weil der Draht i. allg. lang
ist, ist er sehr meßempfindlich. Ist er jedoch länger als eine Wellenlänge des abgestrahlten
Felds, sind sein Übertragungsfaktor und damit die Meßergebnisse schwer zu bestimmen.
Statistische Methoden der Auswertung werden hierzu untersucht.
Ein System aus kleinen Meßsonden kann denselben Teil des Prüflings abdecken wie ein
Testdraht. Weil als Übertragungsfaktor eines solchen Systems der einer Einzelsonde wirksam
ist, lassen sich Ergebnisse aus Messungen mit einem solchen System leichter auswerten.
Jedoch ist die Empfindlichkeit kleiner Sonden i. allg. gering. Der Weg zu einer praktischen
Anwendung führt somit vorerst in die Richtung herkömmlicher Meßantennen, die in einem
beweglichen System geeignete Testflächen abtasten. - (Die Dissertation ist veröffentlicht im Jörg Vogt Verlag, Dresden, Deutschland, http://www.vogtverlag.de, ISBN: 978-3-938860-25-0)In this work the behavior of radiation emitted by large equipment is investigated. The aim of investigation is to improve existing standardized radiation tests. The radiation from an EUT (equipment under test) placed on reflecting ground is described by the distribution of the electric field strength on a hemispheric test area, which encloses the EUT placed in its center. This kind of area guarantees a nearly equal measurement distance to the EUT from every point defined on it. This distance is defined by the radius of the hemisphere. However, measurement distances according to standards are difficult to realize. Because of practical constraints shorter distances will become useful. This requires a smaller test area, to be scanned more easily. At shorter measurement distances field probes are possibly located in the near field of the EUT. Therefore this work investigates the behavior of the field in the vicinity of the EUT to find an adequate transition point, beyond which, field strength values can be extrapolated to distances instructed by standards with confident results. An important parameter of the field strength distribution is the half-power area. It defines that part of the test area where the radiated power exceeds the half of its maximum. The half-power area is related to the directivity of the EUT, which can be approximated by antenna theory or statistics. If the directivity of the EUT is high, the half-power area is small, and the probability to find the field maximum on the test area is low. The size of the half-power area yields to a least number of observation points, equally distributed on the test area, to find the field maximum with a high level of confidence. If the field strength measured at any observation point is considered, the distance to other observation points can be optimized, and the level of confidence in the test can be increased. As a first step in developing a practicable field scanning method is highlighted: the test wire method. This method establishes a measurement executed by a long wire which covers the EUT. At its terminations current can be measured induced by the radiation. Because the wire is long it is very sensitive. However, if it is longer than one wave length of the radiation, the evaluation of results is difficult because of an uncertain transmission factor. Therefore, some statistic methods are applied to describe the behavior of results and their maxima. Also a system of small probes, e. g. short dipoles, can cover the same part of the EUT as a test wire. The measurement with small probes can be evaluated more easily because of a unique transmission factor. However, their sensitivity is lower.
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Sovák, Nikola. "Vytápění průmyslové haly". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227503.
Pełny tekst źródłaStreszczenie:
This theses deals with large objects heating issue, more precisely, heating of industrial halls. The theses focuses primarily on the most effective way of heating, given the economical and hygienical functionality of the object. Heating options of the object and selection of the most appropriate one, according to the specified documents, are also mentioned in this work.
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Fornůsek, Patrik. "Vytápění s využitím obnovitelných zdrojů energie". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265554.
Pełny tekst źródłaStreszczenie:
My diploma thesis deals with heating with the aid of renewable energy sources and thier application in the building of elementary school. This thesis is devided into three parts. The first part is theoretical and is focused on overview of renewable energy sources. It deals with biomass boilers and heat pumps in detail. The second part of this thesis contains comparison of two variants of heat sources and necessary calculations and designs. The first variant is an air-to-water heat pump and the second one is a pellet boiler. The chosen variant is elaborated in detail in the last part. The last part contains technical drawings and technical report.
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Heneková, Barbara. "Vytápění vzdělávacího zařízení". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-371921.
Pełny tekst źródłaStreszczenie:
The aim of diploma thesis is describes the design of heating in a primary school in Trenčín. In this project are two variants of the heat source. The first variant is heat pump of an air/water of split design and second variant is two gas condensing boilers. The thesis includes hot water preparation. In the experimental part of the thesis is deals with heating output of radiators.
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Fröling, Douglas. "Developing a User-CenteredInformation Radiator". Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-362798.
Pełny tekst źródłaStreszczenie:
The popularity of agile software development has grown rapidly over last decades as aresult of today's much volatile development processes with always changingconditions and requirements. Transitioning development teams and wholecorporations into this agile mindset is however most often a difficult undertaking.More demands for effective communication within development teams is just one ofall the aspects having an impact on the transition process.Information visualization tools, such as information radiators, has thus been created asa means for allowing a more efficient communication flow by displaying informationvisually at a glance.This thesis has through the use of a contextual design process designed andimplemented a working prototype of a software-based information radiatorapplication catering to the needs of an agile software development team. Applyingcontextual design contributed to a requirement specification taking the team's currentwork practices into account which in turn defined the features and interface design ofthe application. Lastly, a succeeding implementation process transformed theinformation radiator from concept into a fully working web application prototype.
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Pyszczyková, Anna. "Vytápění střední školy". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240443.
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The introduction of theoretical part deals history of floor heating. Here is an overview of the technology, which was for centuries used for floor heating. Further included in the introductory part of the aggregate materials used, which are used for floor heating, and used. In the next part of the theoretical introduction we are given the best known ecological heat source. These are mainly heat pumps and solar collectors. The last part is made in the proposal which are important values calculated for the design and seamless use of central heating system.
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Janků, Tereza. "Pořizovací a provozní náklady vybraného stavebního objektu". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-372217.
Pełny tekst źródłaStreszczenie:
This Diploma Thesis is focused on initial and operating costs. At first we calculated price for all building and for its other parts, which was calculated by program used for budgeting. After that we calculated partial costs which were done only for specific parts of the construction. These parts were changed and due to these changes we were finding out differences in heat losses and initial costs. Than for individual rooms we were defining heat losses. In this rooms, radiators were designed to cover its heat losses. By summarization of all heat gains we find out boiler´s power and this boiler was used in our building. After that we calculated initial costs for heating system includes radiators and boiler. In the end we compared both kinds of heating systems due to one year operating costs. Results were used for defining final heating system which is the most economic efficiential.
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Bartusek, Jiří. "Dynamika topných ploch a těles včetně regulačních ventilů". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231397.
Pełny tekst źródłaStreszczenie:
This thesis is theoretically described heating surfaces, radiators and regulation valves. There are also described their features, advantages and disadvantages and division according to design. The aim of the work is determine the dynamics characteristics of heating surfaces and radiators including control valves, which are parts of measurement panel. Based on the measurement are determined appropriate characteristics of which are calculated values for regulating. The result of this study can serve as a guide to the practical measurement method of dynamics characteristics of the real-working heating systems, or serve as a template for the settings according to the measured data.
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Bohutínský, Zdeněk. "Energeticky uvědomělá rekonstrukce rodinného domu". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226851.
Pełny tekst źródłaStreszczenie:
The aim of the thesis is a design of the best energy measures for a family house. At first there is carried out an energy assessment of the building. According to results of that survey there are drawn up some variants of measures. Furthermore, based on energy assessment results there is elaborated a project for reconstruction of the heating.
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Dvořák, Václav. "Vytápění staveb. objektu zdroji na různé druhy paliv s vyhodnocením ekonomické výhodnosti". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226821.
Pełny tekst źródłaStreszczenie:
This work deals with the topic „Heating buildings building resources on different types of fuel in assessing economic benefits“. On this theme is elaborated theoretical part, then the topic is applied to the specified building. The project is design central heating, water heating, water heater design power unit. The project is designed in two versions. In the first variant are the heat source gas boilers. In the second variant are the heat source heat pumps.
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Bublan, Tomáš. "Vyhodnocení solární soustavy VUT Fast". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226853.
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The main purpose of the diploma thesis is the evaluation of the solar system at the BUT FCE and the application of the topic on the specified building. The specified building was the story cellarless kindergarten with flat roof. There were proposed two variants of applications of the solar collectors: the solar heating of warm water or combination of solar heating of warm water with the support of heating.