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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.
401

Compensation of Parasitic Inductance for Capacitors Applied to Common- and Differential-Mode Noise Suppression

Yeh, Cheng-Yen 26 July 2007 (has links)
The suitable frequency range of electromagnetic interference (EMI) filters is always limited by the parasitic inductances and capacitances of components. The main object in this research is to develop design rules for lowering parasitic effects due to parasitic inductance of capacitor by using three coupled inductors. In this thesis, the properties and equivalent circuit of three coupled inductors are discussed first. It is found that two negative series inductances can be simultaneously obtained at two ports when the parameters of three coupled inductors are appropriately selected. These two negative inductances can be used to lower parasitic effect of capacitors. In other words, the EMI filter performance can be effectively improved by using this technology. Furthermore, method to completely reduce parasitic inductances is derived. The common mode insertion loss of this design is able to achieve at the rate of -60 dB/decade at high-frequency. For differential mode the insertion loss is even higher to the rate of -100 dB/decade.
402

Hybrid Electromagnetic Forming of Aluminum Alloy Sheet

Imbert Boyd, Jose Miguel Segundo January 2010 (has links)
Electromagnetic (EM) forming is a high-speed forming process that uses the forces induced on a conductive workpiece by a transient high frequency current to form the workpiece into a desired shape. This thesis presents the results of an experimental and numerical study carried out to determine whether an EM forming process could be used to sharpen the radius of part pre-formed using a stamping process. Two processes were studied; a single step EM forming operation and a “hybrid forming” operation consisting of a conventional pre-forming step and an EM corner fill, both considering aluminum alloy AA 5754. The single step EM process proved unable to form acceptable samples due to excessive sample distortion, but was used to gain insight into the EM forming process. The hybrid operation consisted of pre-forming 1 mm AA 5754 sheet into a v-shape with a 20 mm outer radius using a conventional stamping operation and then reducing or “sharpening” the radius to 5 mm using EM forming. Sharpening the radius to 5 mm using conventional stamping was not achievable. The hybrid operation proved successful in forming the 5 mm radius, thus demonstrating that the material could be formed beyond its conventional formability limit using the hybrid operation. Numerical models were used to gain insight into the processes and the challenges involved in their numerical simulation. The numerical simulations showed that EM corner fill operation produces very high strain rates (10,000- 100,000 s-1) and complex three dimensional stress and strain states. The effect of the high strain rates could not be properly assessed, since no constitutive data was available for such high strain rates. The predicted stress states show that the process was not plane stress and that large through-thickness compressive stresses are produced that are favorable to damage suppression and through-thickness shear strains that increase ductility. The high strain rates and the complex stress and strain states are considered the likely causes for the observed increase in formability. The models provided valuable insight, but did not predict the final shape exactly and the possible reasons behind this are analyzed. The research indicates that features that are not achievable using traditional stamping techniques can be obtained with the hybrid EM forming process.
403

Electromagnetic Analysis of Planar Layered Structures

Caliskan, Fatma 14 May 2004 (has links)
ELECTROMAGNETIC ANALYSIS OF PLANAR LAYERED STRUCTURES Fatma Caliskan 169 pages Directed by Dr. Andrew F. Peterson The electrical design of microelectronic devices and their packaging is complicated because of non-ideal attributes of the actual circuit realization. Electromagnetic modeling offers the possibility of accurately predicting the electrical performance of devices and reducing the cost associated with the design process. The proposed research concerns extensions of electromagnetic modeling techniques and their application to microelectronic package design. The method of moments (MoM) is utilized as a technique in modeling and analyzing these designs. Recently, an alternate approach called the locally corrected Nystrm method (LCN) has been applied to solve integral equations in electromagnetics. Recent research suggests that the LCN is well-suited for higher-order implementations and does not require cell-to-cell current continuity in the underlying representation. Thus it may offer advantages over the MoM, especially for problems involving complex 3-D structures. If cell-to-cell continuity is not required, nonconforming meshes may offer simpler geometrical modeling. In this proposal, we consider applying the above techniques to problems in package designs, which often involve multilayer structures, solid or perforated ground planes, embedded passive devices such as capacitors and spiral inductors, and interconnects in horizontal or vertical directions. Several examples will be used to illustrate the modeling.
404

Planar rotary Energy Harvester fabricated by PCB technology

Chen, Po-Hsiu 17 December 2012 (has links)
Small and efficient energy harvesters, as a renewable power supply, draw lots of attention in last few years. This thesis presents a planar rotary electromagnetic generator with copper coils fabricated by printed circuit board (PCB) as inductance and Nd-Fe-B magnets as magnetic member. Coils are fabricated on PCB, which is presumably cost-effective and promising methods. 28-pole Nd-Fe-B magnets with outer diameter of 50 mm and thickness of 2 mm was sintered and magnetized, which can provide magnetic field of 1.4 Tesla. This harvester consists of planar multilayer with multi-pole coils and multi-pole permanent magnet, and the volume of this harvester is about 50x50x2.5 mm3. Finite element analysis is used to design energy harvesting system, and simulation model of the energy harvester is established. In order to confirm the simulation, experiment data are compared with simulation result. The PCB energy harvester prototype can generate induced voltage 1.11 V and 26.54mW output power at rotary speed of 4,000 rpm, and the efficiency of this energy harvester is 31.5%.
405

Controlled-source electromagnetic modeling of the masking effect of marine gas hydrate on a deeper hydrocarbon reservoir

Dickins, David 02 June 2009 (has links)
The ability of marine controlled-source electromagnetic (MCSEM) methods to help image electrical conductivity contrasts below the Earth’s surface makes them useful for both initial reconnaissance surveying for hydrocarbons and for delineating prospective regions of high resistivity in development drilling. A 3-D finite-element MCSEM Fortran algorithm used for forward modeling was developed by Badea. Additional code was written and used for this thesis, with the goal of enforcing more realistic electromagnetic (EM) Dirichlet boundary value conditions. The results of the new boundary conditions on a MCSEM survey model, with a hydrocarbon-saturated region in the subsurface, show that the method does not work as hoped. Constant boundary values were applied to gauge the transmitter-receiver (TXRX) range at which results are not boundary influenced, using a hydrate/hydrocarbon model of the subsurface, at each of the three transmitter frequencies used in this study (1 Hz, 3 Hz, and 10 Hz). Results showed that electric field data were reliable to roughly 5000 m of TX-RX offset for the 1 Hz and 3 Hz cases, and to 6500 m offset for 10 Hz. The gas hydrate/hydrocarbon model was then run with zero-value boundary conditions. The goal was to determine what effect changing parameters of the gas hydrate, including hydrate radius, thickness, and depth, have on the EXEXS (xcomponent of secondary electric field inline with the transmitter dipole axis) curves at various offset, particularly in relation to a hydrocarbon-only model of the subsurface response, so as to evaluate the EM masking effect the hydrate has on the hydrocarbon. The results showed that the x-component of electric field in an inline survey is dominated by the hydrate response, in all cases studied, with a couple of exceptions. One exception is 1 Hz transmitter frequency at 2500 m to 3000 m offset when depth to top of the massive gas hydrate zone was greater or equal to 250 m. Receivers at these offsets would successfully detect the hydrocarbon target.
406

A New Broadband Electromagnetic Band-gap (EBG) Power Planes with High Suppression of Ground Bounce Noise

Chang, Sin-Min 28 April 2004 (has links)
In This Thesis , We primarily introduce some results with suppression of ground bounce noise in high-speed PCB by the formal researchers and summarize their advantages and weaknesses .In the next section .we explain why the EBG (Electromagnetic Band Gap ) design structure is from PBG (Photonic Band Gap ) concept in optical research field and that its principle can suppress GBN . We also summarize their advantages and weaknesses .In the following part, we define five parameters of EBG design structure to find the optimal solution by HFSS simulation method .The optimal solution can enlarge the bandwidth of suppression of GBN to 5.40GHz.We prove the accuracy of HFSS simulation method by actual measurement . When the EBG basic cell gradually compact from n=9.their characteristics are according to 1.central frequency towards high frequency 2.bandwidth of suppression of GBN is more broadband 3. forbiddance band depth becomes wider. Finally we oppose some new EBG design structures to solve some problems of old EBG design structure .These new EBG design structures can enhance signal integrity (SI) and law frequency response. Include three items 1.Meander design structure 2. Buddha design structure 3. Budder design structure .We also prove the accuracy of HFSS simulation method by actual measurement.
407

The Study of Composite Material Package for Optical Transceiver Module with High Shielding Effectiveness

Lin, Cheng-Wei 08 July 2005 (has links)
We investigate the EM properties of four different type composites which are nylon and liquid-crystal polymer with carbon fiber filler composites, woven continuous carbon fiber epoxy composites(balanced twill structure, plain weave structure, uni-direction weave structure), and liquid-crystal polymer with carbon nanotubes filler composites. By comparison of fabrication methods, cost and weight of the optical transceiver module housings, and shielding effectiveness under plane wave and near-field conditions, the woven continuous carbon fiber epoxy composites(balanced twill structure and plain weave structure) show lower cost, lighter weight, and higher EM shielding effectiveness than the other types of composites. Furthermore, they also perform good radiation susceptibility in our measurements. For these reasons, the proposed woven continuous carbon fiber epoxy composite package for an optical transceiver is suitable for use in a low-cost light wave transmission system.
408

Three-dimensional Electromagnetic Performance Analyses of an In-mold Stirrer

Chen, Yen-Ming 31 July 2006 (has links)
The in-mold electromagnetic stirrer is a kind of device which is utilized to stir the molten steel in the steel factory. This thesis provides a detailed three-dimensional electromagnetic analysis of an in-mold electromagnetic stirrer driven by the moving magnetic field produced from stator winding currents. A commercial finite element analysis software will be utilized to calculate the flux density, eddy current, and electromagnetic force from static and dynamic analyses, and the above three physical phenomena are also discussed to obtain the 3-D electromagnetic characteristics. In order to improve the operational properties of the in-mold electromagnetic stirrer, the various position of the stator is modified to observe the distribution of the electromagnetic force. Besides, the magnitude and frequency of the input currents are also adjusted to predict the probable performances during on-site operation.
409

Theoretical and Experimental Investigation of Electrostatic Discharge Phenomena in High-speed PCB

Huang, Yi-Shang 22 July 2003 (has links)
In this work, based on both experimental and theoretical approach, the contact ESD behavior on a PCB circuit is investigated. The discharge mechanisms of ESD (Electrostatic Discharge) phenomena are discussed by both practical measurement and mathematic analysis. Simplified mathematic models include CR-R¡BCR-C and CR-L are proposed to explain the low frequency phenomena of ESD discharge events. Moreover, some experimental setups with good repeatability are demonstrated for measuring the ESD-induced noise on high-speed PCB and some countermeasures are suggested to reduce ESD damage.
410

The Effects of Windshield and Car Body on the Hidden Automotive Antenna

Tang, Tzu-chun 15 July 2009 (has links)
In this thesis, we discuss the subject into four parts. Firstly, we introduce the telematics for automotive. Secondary, we study the effects of locations of the hidden antenna. Thirdly, we discuss the effects of the windshield to the hidden antenna as we place the antenna on the windshield, then, the window film is attached to the windshield. We conduct implementation and measurement to analyze the effect of the film to the antenna. Finally, we find that the antenna gain is degraded in certain receiving angle due to the car body as we place the antenna at the corner of the windshield. In order to improve this, we design an EBG structure and place it between the antenna and the car body. The simulation result indicates that the EBG structure not only improves the gain in certain receiving angles but also reduces the induced current intensity on the car body.

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