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41.
42.
We advocate the use of quickly‐adjustable, computer‐controlled color spectra in photography, lighting and displays. We present an optical relay system that allows mechanical or electronic color spectrum control and use it to modify a conventional camera and projector. We use a diffraction grating to disperse the rays into different colors, and introduce a mask (or LCD/DMD) in the optical path to modulate the spectrum. We analyze the trade‐offs and limitations of this design, and demonstrate its use in a camera, projector and light source. We propose applications such as adaptive color primaries, metamer detection, scene contrast enhancement, photographing fluorescent objects, and high dynamic range photography using spectrum modulation. 相似文献
43.
Iris Reinbacher Marc Benkert Marc van Kreveld Joseph S. B. Mitchell Jack Snoeyink Alexander Wolff 《Algorithmica》2008,50(3):386-414
In geographic information retrieval, queries often name geographic regions that do not have a well-defined boundary, such
as “Southern France.” We provide two algorithmic approaches to the problem of computing reasonable boundaries of such regions
based on data points that have evidence indicating that they lie either inside or outside the region. Our problem formulation
leads to a number of subproblems related to red-blue point separation and minimum-perimeter polygons, many of which we solve
algorithmically. We give experimental results from our implementation and a comparison of the two approaches.
This research is supported by the EU-IST Project No. IST-2001-35047 (SPIRIT) and by grant WO 758/4-2 of the German Research
Foundation (DFG). 相似文献
44.
Observed finger behaviour during computer mouse use 总被引:1,自引:0,他引:1
Two-button computer mouse users may exhibit sustained, static finger lifting behaviours to prevent inadvertent activations by avoiding finger pressure on the buttons, which leads to prolonged, static finger extensor muscle loading. One hundred graduate students were observed during normal computer work in a university computer facility to qualify and quantify the prevalence of lifted finger behaviours and extended finger postures, as well as wrist/forearm and grip behaviour, during specific mouse activities. The highest prevalences observed were 48% of the students lifted their middle finger during mouse drag activities, and 23% extended their middle finger while moving the mouse. In addition, 98% of the students rested their wrist and forearm (77%) or wrist only (21%) on the workstation surface, and 97% had an extended wrist posture (15 degrees -30 degrees ) when using the mouse. Potential applications of these findings include future computer input device designs to reduce finger lifting behaviour and exposures to risk factors of hand/forearm musculoskeletal pain. 相似文献
45.
每年1月,汽车音响行业都会翘首以盼阿尔派音响改装样板车问世。一般,在拉斯维加斯的国际消费类电子产品展览会(CES)上,阿尔派设计人员都会向人们展示其样板车。在过 相似文献
46.
47.
A white-light continuum is used to seed a two-stage optical parametric amplifier pumped by the second harmonic of a regeneratively amplified Ti:sapphire laser system operating at 824 nm. Microjoule energies are achieved in the signal branch, which is tunable from 472 to 785 nm. Near-transform-limited sub-200-fs pulses are attainable over the vast majority of the tuning range. 相似文献
48.
Silvia?Versari Livia?Barenghi Jack?van?Loon Silvia?BradamanteEmail author 《Microgravity science and technology》2016,28(1):19-28
Due to spaceflight, astronauts experience serious, weightlessness-induced bone loss because of an unbalanced process of bone remodeling that involves bone marrow mesenchymal stem cells (BMSCs), as well as osteoblasts, osteocytes, and osteoclasts. The effects of microgravity on osteo-cells have been extensively studied, but it is only recently that consideration has been given to the role of BMSCs. Previous researches indicated that human BMSCs cultured in simulated microgravity (sim-μg) alter their proliferation and differentiation. The spaceflight opportunities for biomedical experiments are rare and suffer from a number of operative constraints that could bias the validity of the experiment itself, but remain a unique opportunity to confirm and explain the effects due to microgravity, that are only partially activated/detectable in simulated conditions. For this reason, we carefully prepared the SCD – STEM CELLS DIFFERENTIATION experiment, selected by the European Space Agency (ESA) and now on the International Space Station (ISS). Here we present the preparatory studies performed on ground to adapt the project to the spaceflight constraints in terms of culture conditions, fixation and storage of human BMSCs in space aiming at satisfying the biological requirements mandatory to retrieve suitable samples for post-flight analyses. We expect to understand better the molecular mechanisms governing human BMSC growth and differentiation hoping to outline new countermeasures against astronaut bone loss. 相似文献
49.
Single point incremental forming: state-of-the-art and prospects 总被引:1,自引:0,他引:1
Joost R. Duflou Anne-Marie Habraken Jian Cao Rajiv Malhotra Markus Bambach Dave Adams Hans Vanhove Amirahmad Mohammadi Jack Jeswiet 《International Journal of Material Forming》2018,11(6):743-773
Incremental sheet metal forming in general and Single Point Incremental Forming (SPIF) specifically have gone through a period of intensive development with growing attention from research institutes worldwide. The result of these efforts is significant progress in the understanding of the underlying forming mechanisms and opportunities as well as limitations associated with this category of flexible forming processes. Furthermore, creative process design efforts have enhanced the process capabilities and process planning methods. Also, simulation capabilities have evolved substantially. This review paper aims to provide an overview of the body of knowledge with respect to Single Point Incremental Forming. Without claiming to be exhaustive, each section aims for an up-to-date state-of-the-art review with corresponding conclusions on scientific progress and outlook on expected further developments. 相似文献
50.
Jack L. Beuth 《International Journal of Fracture》1996,77(4):305-321
In modeling a crack along a distinct interface between dissimilar elastic materials, the ratio of mode I to mode II stress intensity factors or energy release rates is typically not unique, due to oscillatory behavior of near-tip stresses and displacements. Although methods have been developed for comparing mode mixes for isotropic interfacial fracture problems, this behavior currently limits the applicability of interfacial fracture mechanics in predicting delamination in layered materials without isotropic symmetry. The virtual crack closure technique (VCCT) is a method used to extract mode I and mode II energy release rate components from numerical fracture solutions. Energy release rate components extracted from an oscillatory solution using the VCCT are not unique due to their dependence on the virtual crack extension length, . In this work, a method is presented for using the VCCT to extract -independent energy release rate quantities for the case of an interface crack between two in-plane orthotropic materials. The method does not involve altering the analysis to eliminate its oscillatory behavior and it is similar to existing methods for extracting a mode mix from isotropic interfacial fracture models. Knowledge of near-tip fields is used to determine the explicit dependence of energy release rate parameters. Energy release rates are then defined that are separated from the oscillatory dependence on . A modified VCCT using these energy release rate definitions is applied to results from finite element analyses, showing that -independent energy release rate quantities result. The modified technique has potential as a consistent method for extracting a mode mix from numerical solutions. The -independent energy release rate quantities extracted using this technique can also aid numerical modelers, serving as guides for testing the convergence of finite element models. Direct applications of this work include the analysis of planar composite delamination problems, where plies or debonded laminates are modeled as in-plane orthotropic materials. 相似文献