Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 33 for “"active element"”.
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New Approach to finding Active Element Patterns for Large Arrays
In this study a new approach to active-element pattern analysis, for large phased array antennas, was created using Floquet's theorem. The classic approach to finding active-element patterns uses a full array simulation that can become slow and produce patterns that are specific to certain elements …
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A NOVEL DESIGN OF AN ALL-OPTICAL BISTABLE DEVICE USING A SINGLE ACTIVE ELEMENT
… is to develop low power and fast responding elements. Specically, in the eld of analog to digital converters (ADCs), higher modulation rates as well as enhanced power eciency are desired. The key component in such circuits, is the bistable switching device, also known as Schmitt trigger …
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Analysis of phased array antenna radiation patterns including mutual coupling
… are the classical array analysis method and the active element pattern methods. The theoretical derivations of the active element pattern methods are presented and the various types of active element patterns are defined. Also, a new method based on active element patterns, the hybrid active …
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Sonar beamforming based upon monaural localisation techniques
… is usually accomplished using a multi-element transducer array. To obtain high resolution, such a system is costly and complex. In contrast, many mammals are capable of good angular resolution using only a single active element surrounded by an irregular reflector – the ear. A study of …
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Hybrid Active/Passive Models with Frequency Dependent Damping
… (PCLD). When this constraining layer is an active element, the treatment is called active constrained layer damping (ACLD). Recently, the investigation of ACLD treatments has shown it to be an effective method of vibration suppression. In this work, two new hybrid configurations are …
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Isolation and Characterization of a Full Length Retrotransposon: CR1
<p>Transposable elements (TE) have been found in all genomes and have clearly had a major impact on genomic evolution. The described research takes advantage of an abundant transposable element present in the genomes of Anseriformes, called Chicken Repeat 1 (CR1). Previous studies in Anseriformes …
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Mejoramiento de un sistema mecanico por control activo
… of improving its dynamics by the addition of an active element. The system is simulated by idealized masses, springs and dashpots. The proposed active compQ nent is visualized as a servo mechanism ora force transducer which recieves one of the variables of the system as an input and yields a …
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Analysis of Highly Coupled Wideband Antenna Arrays Using Scattering Parameter Network Models
Wideband phased arrays require very tight element spacing to permit wide angle scanning of the main beam over the wide bandwidth. The consequence of tight spacing is very high mutual coupling among the elements in the array. Previous efforts by Virginia Tech Antenna Group has shown that the strong …
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ALL-OPTICAL DELTA-SIGMA MODULATOR DESIGN AND IMPLEMENTATION
… switch” designed and implemented by using active element like semiconductor optical amplifier (SOA) and other passive elements like optical filter, isolator and coupler. All experiments are done on optical table and proper results achieved. Thus the new bi-stable switch is designed and …
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Low Profile, Printed Circuit, Dual-Band, Dual-Polarized Antenna Elements and Arrays
Dual-band antenna elements that support dual-polarization provide ideal performance for applications including space-based platforms, multifunction radar, wireless communications, and personal electronic devices. In many communications and radar applications, a dual-band, dual-polarization antenna …
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A Sketch of Sound
… and the second. The seventh is used as an active element, while the second remains motionless. Rhythmic imitations among the same groups of instruments create echo effects. Through a variety of musical means, this work offers a perspective on the nature and essence of sound.
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Literary Dimensions of National Identity: The Historical Novel of the Late Soviet Period (1960s--1980s)
… the Soviet historical novel as an active element in a state-sponsored identity construction process where the official doctrines of the existing political system often played only minor roles. The theoretical tools of cultural anthropology highlight the possibilities that are …
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From Hope to Disillusion? A Literary and Cultural History of the Whitlam Period, 1966-1975
… relevant theoretical argument that culture is an active element of social development, this thesis examines the cultural causes of the defeat of Whitlam and the rise to dominance of neo-classical liberal public policy. It is argued that the primary cultural cause of these social developments is a …
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Design and Manufacture of an Ultrasonic Transducer for Long-term High Temperature Operation
… on two different piezoelectric crystals as the active element: gallium phosphate and lithium niobate. A high Curie temperature of 1200 째C for lithium niobate and a high phase transition temperature of 970 째C for gallium phosphate, make the two piezoelements suitable for our application. A …
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Biomedical ultrasonics, cavitation, and sonoporation
… transducer, using lithium niobate as the active element. The transducer was capable of creating 2.5×3.4 (mm)2 lesions without affecting surrounding tissue. Such disruptive effects of ultrasound also have applications outside medicine. Since cyanobacteria contain gas vesicles, we …
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Isotopic study of uranium: determining the isotopic fractionation of uranium during abiotic reduction with iron(II)
… and mobility in groundwater. It is a redox active element in which the oxidation state can change by the addition or removal of electrons. In one method of groundwater remediation, mobile, hexavalent uranium (U(VI)) can be reduced to immobile, tetravalent uranium (U(IV)) by microbial or …
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Microtransfer printing of elastomeric active composites
Soft active polymeric composites are of great interest in many fields, including soft robotics, flexible electronics, and wearable technologies. This kind of 3D heterogeneous integration of different materials to form a functional membrane is achieved through a novel fabrication process that …
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Dynamic dispatch of direct load control
… of the power system, is an important and active element of Load Management (LM). Currently attention has focussed on the integration of DLC into system operations. However, as yet, DLC is regarded as a discretionary resource to be used by the system operator based on informed judgment. The …
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Teaching itself: a mythology of learning in theory and practice
… also to make the creation of the commentary an active element of the final version. In this I am partly acknowledging the influence of Barthes’ famous book lengthy critical study of his own work, ‘RB by RB’. I would like to think that the structures, fluidity and playfulness of the commentary …
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Isotopes of selenium as redox tracers of geochemical processes influencing the export and behavior of selenium contamination in coal mine watersheds
Selenium is a redox-active element that is necessary for life in small quantities but causes toxic effects for wildlife above 5 μg/L in water and for humans above 50 μg/L in drinking water. Se contamination is released by oxidative weathering of Se-bearing shales, and this contamination is often …
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