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LTE MIMO Antenna with High Isolation for Laptop ComputerWu, Tsung-Ju 14 June 2012 (has links)
For applications of wireless communication of the fourth generation (4G LTE), the technique of using a printed parallel-resonant spiral strip for bandwidth enhancement of a small-size planar laptop computer (especially the thin Ultrabook) antenna for the LTE operation is first presented. The antenna is printed on a thin FR4 substrate of small size 45 x 9 mm2 with a simple uniplanar structure which is promising for Ultrabook application. Based on the proposed antenna structure, its application for MIMO operation to achieve enhanced isolation is also analyzed in this thesis. Different from the works for the relatively much smaller ground plane conditions such as in the mobile phones, the effect of different size of the supporting conductive plate of the upper corner of the Ultrabook is discussed for the isolation issue of the MIMO antennas. Finally, the technique of isolation improvement in the LTE700 band for the MIMO operation in the Ultrabook is presented.
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Study of Profile Rolling by Four-high Rolling MillsSu, Chien-Wen 10 September 2012 (has links)
Profile strips have been used in various industries and now the demand of profile strip is still growing. Due to different reductions at different parts of the strips, profile strips after rolling generate a defect which looks like a wave. This study will design and manufacture a four-high profile rolling mill, which can roll profile strips. Experiments and finite element simulation are conducted to discuss the effects of different parameters on strip size and the defect of the profiled strips.
In this study, a finite element analysis software is used to establish profile rolling models with different material setting mode, reduction, temperature, material, tension, and roll shape. From the simulation results, the effects of these parameters on the defects are discussed. Secondly, profiled rolls are designed and a heating equipment is added on the four-high rolling mill, and rolling experiments with different reduction, materials, passes of process, roll shape and temperature are conducted. From the experimental results the effects of these parameters on size of the defect of profile strip are discussed. Finally, from the comparisons between simulation results and experiment results, the feasibility of finite element models are verified.
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Lateral Stiffness Of Unstiffened Steel Plate Shear Wall SystemsAtasoy, Mehmet 01 January 2008 (has links) (PDF)
Finite element method and strip method are two widely used techniques for analyzing steel plate shear wall (SPSW) systems. Past research mostly focused on the prediction of lateral load capacity of these systems using these numerical methods. Apart from the lateral load carrying capacity, the lateral stiffness of the wall system needs to be determined for a satisfactory design. Lateral displacements and the fundamental natural frequency of the SPSW system are directly influenced by the lateral stiffness. In this study the accuracy of the finite element method and strip method of analysis are assessed by making comparisons with experimental findings. Comparisons revealed that both methods provide in general solutions with acceptable accuracy. While both methods offer acceptable solutions sophisticated computer models need to be generated. In this study two alternative methods are developed. The first one is an approximate hand method based on the deep beam theory. The classical deep beam theory is modified in the light of parametric studies performed on restrained thin plates under pure shear and pure bending. The second one is a computer method based on truss analogy. Stiffness predictions using the two alternative methods are found to compare well with the experimental findings. In addition, lateral stiffness predictions of the alternate methods are compared against the solutions provided using finite element and strip method of analysis for a class of test structures. These comparisons revealed that the developed methods provide estimates with acceptable accuracy and are simpler than the traditional analysis techniques.
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Finite Strip With Rigid Ends And Edge NotchesErozkan, Deniz 01 August 2009 (has links) (PDF)
This study considers a symmetrical finite strip with a length of 2L and a width of 2h containing two collinear edge cracks located at the center of the strip. Each edge crack has a width h& / #8211 / a. Two ends of the finite strip are bonded to two rigid plates through which uniformly distributed axial tensile loads of intensity p0 are applied. The finite strip is assumed to be made of a linearly elastic and isotropic material. For the solution of the finite strip problem, an infinite strip of width 2h containing two internal cracks of width b& / #8211 / a at y=0 and two rigid inclusions of width 2c at y=± / L is considered. When the width of rigid inclusions approach the width of the strip, the portion of the infinite strip between the inclusions becomes identical with the finite strip problem. When the outer edges of the internal cracks approach the edge of the strip, they become edge cracks (notches). Governing equations are solved by using Fourier transform technique and these equations are reduced to a system of three singular integral equations. By using Gauss-Lobatto and Gauss-Jacobi integration formulas, these three singular integral equations are converted to a system of linear algebraic equations which is solved numerically.
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Study on Architecture-Oriented Hot Strip Mill Statistical Process Computer ModelLi, Ting-li 05 January 2009 (has links)
Hot-rolled steel products occupy a key position, between upstream and downstream, in the steel industry chain. In this country, revenue of hot-rolled strip steel products maintains the greatest proportion among all steel products. Continuous pursuit of knowledge progress and growth plays a significant support to sustainable enterprises and gives them a vigorous operational strength in the face of international competition.
During the hot strip steel manufacturing process, as the second-level standard of the computer integrated manufacturing system in a steel plant describes, in addition to those needed information related with real-time electronic control equipment dealt by process control computers, how does hot strip mill statistical process computer, abbreviated HSMSPC, utilize statistical analysis and information processing also challenges the future competitiveness. This research engages in a genuine hot strip mill statistical process computer system developed by a well-known steel corporation located in Taiwan, adopting structure behavior coalescence, abbreviated as SBC, six golden rules to build up the architecture-oriented hot strip mill statistical process computer model, abbreviated as AOHSMSPCM. AOHSMSPCM shall construct a hot strip mill statistical process computer system in an architecture-oriented way so that it is able to fully express the operational act and information extraction which cover system structures and system behaviors as well; subsequently, the hot strip mill statistical process computer system will produce higher added value in the face of the production line variability, replicate update, knowledge management, and so on.
AOHSMSPCM begins with the analysis layer of system architecture. In this research, system structures and system behaviors are well described in the HSMSPC analysis layer. Besides this, easy to duplicate and extension of scalability are thoroughly elaborated in this research. Finally, this research comes up with "Strengthening the variability control of a hot strip mill", "Preserving assets of corporate knowledge" and "Upgrading process technologies of production lines" as three benefits that AOHSMSPCM contributes to the enterprise.
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Passive Earth Pressure Coefficients And There Applications In The Uplift Capacity Of AnchorsNayak, Sitaram 04 1900 (has links)
The problem of passive earth pressure is one of the important topics in Geotechnical engineering. At attempt is made in this thesis to generate passive earth pressure coefficients for general c-Φ soils using logarithmic spiral failure surface by limit equilibrium approach. Method of slices for the determination of passive force in c-Φsoils is presented and the method is extended to a typical problem of two layered soil system. The application of passive earth pressure coefficients has been demonstrated for pullout capacity of inclined strip anchors in sloping ground. A semi-empirical approach for the determination of displacement-related passive earth pressure is presented.
The thesis is organized in seven chapters. In Ch.2, a brief summary of relevant literature is presented along with the scope of the thesis. In Ch. 3, limit equilibrium approach for the determination of the passive earth pressure in soils is presented. The
passive earth pressure coefficients are developed for δ/Φ= - 1, - ¾ , -2/3, - ½, 0, ½, ¾
1; ψ = -60º, -45º, -30º, -20º, -10º, 0º,10º,20º,30º and 45º; i= -30º, -20º, -10º,0º,10º,20º and 30º where δ is the wall friction angle, Φ is the angle of internal friction, Ψ is the
inclination of the wall with the vertical and i is the ground inclination with the horizontal. Ch.4 deals with the method of slices. Satisfying all the three equilibrium conditions and using interstice friction as a variable, passive earth pressure coefficients are obtained for soils. Extension of the method to a two layered soil system is demonstrated by an illustrative example. A generalised approach for the determination of uplift capacity of inclined strip anchors in sloping ground subjected to surcharge is presented in Ch. 5. Expressions are provided for the determination of pullout capacity of deep anchors. Displacement-related passive earth pressure is discussed in Ch. 6. Using the earlier experimental observations on the passive earth pressure measurements with displacements, expressions have been fitted for the determination of displacement-related passive earth pressure for the three modes of rigid body movements viz., translation, rotation about the top and rotation about the bottom. The conclusions drawn from the present investigations are listed in Ch 7.
(Pl see the original document for abstract)
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Silicon Strip Detectors for Scanned Multi-Slit X-Ray ImagingLundqvist, Mats January 2003 (has links)
<p>Digital imaging systems for medical applications must bebased upon highly efficient detectors to ensure low patientdose. This is particularly important in screening mammographybecause of the large number healthy women that is examined. Amammography system must also provide high spatial and contrastresolution. Different approaches are compared in this thesis,and it is argued that a system based on photon countingdetectors in a scanned multi-slit geometry provides aperformance superior to established technologies.</p><p>The system is realized using silicon strip detectorsirradiated at a small angle relative to the wafer surface,thereby offering large absorption depth. A linear pixelarray isscanned across the breast to obtain the complete image.Pulse-processing electronics rejecting all detector andelectronics noise count the number of photons that aredetected, forming the pixel values of the image.</p><p>Optimization of the detector design is discussed in detail.The detector has been carefully simulated to investigate chargemotion and signal formation after photoninteraction. Based onthese simulations, the impact of the detector characteristicson the image quality has been evaluated.</p><p>Detectors have been manufactured and evaluated both assingle components and as part of experimental imaging devicesincluding custom readout electronics. Presented in this thesisare the measured detector characteristics including a verifi-cation of charge collection efficiency and confirmation thatthe quantum efficiency is 90% for a typical mammographyspectrum. Modulation transfer functions and noise power spectrawere recorded and the detective quantum efficiency calculated.A prototype mammography system was also assembled and themodulation transfer function recorded. The interpretation ofthe modulation transfer function and detective quantumefficiency is discussed for digital systems in general and fora scanned multi-slit system in particular.</p><p><b>Keywords:</b>x-ray, imaging, silicon, detector, digital,mammography, scanning, photon counting.</p>
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Some aspects on lubrication and roll wear in rolling millsTahir, Mohammed January 2003 (has links)
<p>The thesis is focused on lubricants and roll wear in striprolling.</p><p>Regarding lubricants, the possibility of introducing newones, which are less detrimental towards environment, isstudied in laboratory scale. This is done for cold rolling,both of an Al- alloy and a low carbon steel. The lubricationperformance of such newly developedwater-basedsynthetic lubricants is compared with currently used mineraloils and emulsions. By using the experimental method of"forward slip" measurements combined with slab methodcalculations and FE- simulations, friction coefficients areevaluated for different single pass reductions. Lubricantsbearing capacity and the product surface roughness are alsoevaluated. The results are encouraging.</p><p>A synthetic water-based lubricant, used in the cold rollingof an Al- alloy, showed good lubrication capability, betterthan the mineral oil but worse than the emulsion. The rolledAl- strip finish was found to be finest for the syntheticlubricant followed by the mineral oil and the emulsion. Similarresults were obtained from the steel rolling. Here foursynthetic lubricants were compared with two mineral oils andone emulsion. The best lubricant was found to be one of thewater-based synthetics, showing the lowest value of thefriction coefficient and a smooth product surface.</p><p>The aim of the wear study is to develop an accurateroll-wear prediction for hot strip finishing mills, which takesmore influential parameters into account. A new model of higheraccuracy is presented. This model is based on a large amount ofproduction campaigns. The strategy of the work is describedbelow.</p><p>After a comprehensive literature study a promising modelstructure was found. The corresponding equation is tested ontwo hot strip mills. Predicted wear is found to be inqualitative agreement with industrial experience and measuredwear. Thus the structuretaking the influence of back-uprolls into accountwas chosen for further development.This was done on behalf of results obtained from one mill builtup by six stands and three different work-roll materials.Campaigns of "mixed" and "similar" strip grades were used. Theobtained model is tested successfully in two other hot stripmills.</p><p>Contradictory to the currently used on-line model, the newmodel takes the work roll flattening and back-up rolls contactarea into consideration. Also the influence of strip- and workroll grades is included. The model enables increased rolledstrip length and prolonged lifetime of the rolls, because ofimproved process control. Further more, grinding cost and timefor roll changing can be minimized. Of course thesepossibilities should result in considerable energy saving.</p><p><b>Keywords:</b>Strip rolling, lubricants, environment, rollwear modeling, production campaigns, regression analysis</p>
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Remote sensing techniques for monitoring coal surface mining and reclamation in the Power River BasinAlden, Matthew G. January 2009 (has links)
Thesis (M.S.)--Ohio University, November, 2009. / Title from PDF t.p. Includes bibliographical references.
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Design and optimization of broadband planar baluns and dipole antennasMelais, Sergio E. 01 January 2005 (has links)
The effective output balancing capability of this balun is proven by the close agreement between the measured and simulated results. Diode detectors are nonlinear devices used for extraction of DC from free space transmission, achieving RF to DC conversion. Detectors are of popular use today in RF-ID tags, virtual batteries, power scavenging, and many other portable applications. The dominating factor on the performance for this device is responsivity (mV/mW), which depends on the input matching, and in the relation of power level to input impedance. Here, an accurate comparison between model measured detectors has been accomplished, and a sensitivity study has been applied to the input impedance to represent variations in responsivity due to input mismatch.At last an End-Loaded Planar Open-Sleeve Dipole (ELPOSD) is realized resulting on a printed dipole structure offering broadband response.
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