412 research outputs found

    Continuous variable quantum teleportation with non-Gaussian resources

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    We investigate continuous variable quantum teleportation using non-Gaussian states of the radiation field as entangled resources. We compare the performance of different classes of degaussified resources, including two-mode photon-added and two-mode photon-subtracted squeezed states. We then introduce a class of two-mode squeezed Bell-like states with one-parameter dependence for optimization. These states interpolate between and include as subcases different classes of degaussified resources. We show that optimized squeezed Bell-like resources yield a remarkable improvement in the fidelity of teleportation both for coherent and nonclassical input states. The investigation reveals that the optimal non-Gaussian resources for continuous variable teleportation are those that most closely realize the simultaneous maximization of the content of entanglement, the degree of affinity with the two-mode squeezed vacuum and the, suitably measured, amount of non-Gaussianity.Comment: 12 pages, 12 figure

    The development of a pile-fabric patterning system

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    The aim of this research, sponsored by the Science Research Council, was to develop a high-speed patterning system intended primarily for application to the locked-loop pile-fabric process invented and developed in the Department of Mechanical Engineering at Loughborough University of Technology. Current commercial versions of the locked-loop pile-fabric producing machines, manufactured under URDC. licence and marketed under the trade name ‘Locstitch’, have their market potential concentrated on the field of good quality pile-fabric production but limited to plain unpatterned types. [Continues.

    Sensor enclosures: example application and implications for data coherence

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    Sensors deployed in natural environments, such as rivers, beaches and glaciers, experience large forces and damaging environmental conditions. Sensors need to be robust, securely operate for extended time periods and be readily relocated and serviced. The sensors must be housed in materials that mimic natural conditions of size, density, shape and roughness. We have developed an encasement system for sensors required to measure large forces experienced by mobile river sediment grains. Sensors are housed within two discrete cases that are rigidly conjoined. The inner case exactly fits the sensor, radio components and power source. This case can be mounted within outer cases of any larger size and can be precisely moulded to match the shapes of natural sediment. Total grain mass can be controlled by packing the outer case with dense material. Case design uses Solid-WorksTM software, and shape-matching involved 3D laser scanning of natural pebbles. The cases were printed using a HP DesignjetTM 3D printer that generates high precision parts that lock rigidly in place. The casings are watertight and robust. Laboratory testing produces accurate results over a wider range of accelerations than previously reported

    Traženje forme ljuski zasnovano na izogeometrijskoj analizi

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    The paper reviews potentials of the application of isogeometric analysis (IGA) in the pro­cesses of form-finding of shell structures. Shaping of those specific spatial structural typolo­gies is determined by consideration of the form-structure interrelation, therefore the sustainable approach to design implies application of form-finding techniques. In this paper, we applied the frequently used form-finding principle a inverted model strategy, more precisely concept of inverted displacements. Contrary to the similar studies which apply standard finite element (FE) discretization, we proposed an application of isogeometric modeling of the structure. Isogeome­try implies analysis based on the exact definition of the initial geometry, facilitating design and analysis by application on the single data type - model. Advantage of the conservation of geometric representation is especially evident in the case of shell structure designs, bearing in mind their continuously curved geometry. We applied NURBS based isogeometric analysis in which geometry and displacement field are described by NURBS surfaces. Modeling of the structural performances was conducted by isogeometric shell elements. Presented numerical experiment has a function to confirm the effectiveness of the proposed approach.Radom se razmatraju potencijali primene izogeometrijske analize u procesima traženja formi ljuski. Oblikovanje ovih specifičnih prostornih strukturalnih tipologija određeno je razmatranjem interrelacije forma-struktura, zbog čega održivi pristup njihovom projektovanju podra­zumeva primenu tehnika traženja forme. U okviru ovog rada primenjena je strategija obrnutog modela, često korišćen princip traženja forme, tačnije koncept obrnutih pomeranja. Za razliku od sličnih istraživanja u kojima se koristi standardna diskretizacija konačnim elementima (FE), ovim radom se predlaže izogeometrijsko modelovanje strukture. Izogeometrija podrazumeva analizu zasnovanu na egzaktnoj definiciji početne geometrije, čime je omogućeno projektovanje i analiza upotrebom jedinstvenog tipa podataka - modela. Prednost konzervacije geometrijske reprezentacije posebno dolazi do izražaja u slučaju projektovanja ljuski imajući u vidu njihovu kontinualno zakrivljenu geometriju. Primenjena je NURBS izogeometrijska analiza, u kojoj se geometrija i polje pomeranja opisuju korišćenjem NURBS površi. Modelovanje strukturalnih performansi izvršeno je korišćenjem izogeometrijskog elementa ljuske. Prikazan numerički ek­speriment u funkciji je potvrđivanja efikasnosti predloženog pristupa

    Metamodels Resulting from Two Different Geometry Morphing Approaches Are Suitable to Direct the Modification of Structure-Born Noise Transfer in the Digital Design Phase

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    Noise vibration and harshness (NVH) development often takes place in the later development phases. Shifting the optimization to the early digital development phase enables more parameters to participate in the optimization and leads to a more holistic development process. Digital NVH development often modifies system and component frequency response functions (FRFs) using finite element (FE) simulation. Currently, the often manual process of creating new FE models for modified designs makes a systematic evaluation of many designs difficult and time-consuming. In this paper, we take on these difficulties and use both a Direct Morphing approach and a Box Morphing approach to automatically adopt the first existing FE models to modified designs. We use the generated simulation results to fit metamodels describing the correlation between geometrical parameters and characteristic FRF values. These metamodels provide an easy and fast to use tool for designers to consider NVH demands. In a simulation example, we demonstrate the capabilities by modifying the kinematic hard points of a vehicle suspension and using them to modify the noise transfer sensitivity. We show that the metamodels can lead the digital design process to intuitively and specifically reduce characteristic component FRF values by changing the location of the component hard points

    Super stealth dicing of transparent solids with nanometric precision

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    Laser cutting of semiconductor wafers and transparent dielectrics has become a dominant process in manufacturing industries, encompassing a wide range of applications from flat display panels to microelectronic chips. Limited by Heisenberg's uncertainty principle imposed on the beam width and divergence angle of laser focus, a trade-off must be made between cutting accuracy and aspect ratio in conventional laser processing, which are typically at a micrometer and a hundred level. Herein, we propose a method to circumvent this limitation. It is based on the laser modification induced by a back-scattering interference crawling mechanism, which creates a positive feedback loop for elongating and homogenizing longitudinal energy deposition during laser-matter interaction. Consequently, cutting width on the scale of tens of nanometers and aspect ratio 104\sim 10^4 were simultaneously achieved. We refer to this technique as ``super stealth dicing'', which is based on an analytical model and validated through numerical simulations, ensuring its broad applicability. It can be applied to various transparent functional solids, such as glass, laser crystal, ferroelectric, and semiconductor, and is elevating the precision of future advanced laser dicing, patterning, and drilling into the nanometric era.Comment: 29 pages, 5 figure

    Diversity and Distribution of the Desert Stink Beetles: Systematics of the Amphidorini LeConte, 1862 (Coleoptera: Tenebrionidae)

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    abstract: Understanding the diversity, evolutionary relationships, and geographic distribution of species is foundational knowledge in biology. However, this knowledge is lacking for many diverse lineages of the tree of life. This is the case for the desert stink beetles in the tribe Amphidorini LeConte, 1862 (Coleoptera: Tenebrionidae) – a lineage of arid-adapted flightless beetles found throughout western North America. Four interconnected studies that jointly increase our knowledge of this group are presented. First, the darkling beetle fauna of the Algodones sand dunes in southern California is examined as a case study to explore the scientific practice of checklist creation. An updated list of the species known from this region is presented, with a critical focus on material now made available through digitization and global aggregation. This part concludes with recommendations for future biodiversity checklist authors. Second, the psammophilic genus Trogloderus LeConte, 1879 is revised. Six new species are described, and the first, multi-gene phylogeny for the genus is inferred. In addition, historical biogeographic reconstructions along with novel hypotheses of speciation patterns within the Intermountain Region are given. In particular, the Kaibab Plateau and Kaiparowitz Formation are found to have promoted speciation on the Colorado Plateau. The Owens Valley and prehistoric Bouse Embayment are similarly hypothesized to drive species diversification in southern California. Third, a novel phylogenomic analysis for the tribe Amphidorini is presented, based on 29 de novo partial transcriptomes. Three putative ortholog sets were discovered and analyzed to infer the relationships between species groups and genera. The existing classification of the tribe is found to be highly inadequate, though the earliest-diverging relationships within the tribe are still in question. Finally, the new phylogenetic framework is used to provide a genus-level revision for the Amphidorini, which previously contained six valid genera and 253 valid species. This updated classification includes more than 100 taxonomic changes and results in the revised tribe consisting of 16 genera, with three being described as new to science.Dissertation/ThesisDoctoral Dissertation Evolutionary Biology 201

    Computer Assisted Relief Generation - a Survey

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    In this paper we present an overview of the achievements accomplished to date in the field of computer aided relief generation. We delineate the problem, classify the different solutions, analyze similarities, investigate the evelopment and review the approaches according to their particular relative strengths and weaknesses. In consequence this survey is likewise addressed to researchers and artists through providing valuable insights into the theory behind the different concepts in this field and augmenting the options available among the methods presented with regard to practical application
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