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81.
82.
Holger Schnädelbach Tim Coughlan Genovefa Kefalidou Derek McAuley Rupert Meese 《International journal of human-computer interaction》2013,29(11):790-804
The Creativity Bento Box is a physical resource pack, designed to support casual social interaction and break taking in an intensive, computer-mediated social activity. It was developed within the Creativity Greenhouse project, which piloted a mechanism to create research proposals and distribute funding at a distance. This involved facilitated phases of collaboration and competition over multiple days of computer-mediated work, where participants communicate and interact through a virtual world. During the iterative development process, the lack of time for socializing, the intense focus on virtual resources, and a lack of time spent away from the screen were reported as negative issues in feedback from participants. This article reports on the development of the Creativity Bento Box and how it helped to address these issues. By providing physical resources that contrasted with the properties of the virtual world, it supported people to socialize and take breaks from their primary activity, allowed them to include physical space and artifacts in their interactions, and provoked moves away from the otherwise intense focus on the computer. The article reflects on the roles of the Bento Box as a gift, in bridging between physical and virtual contexts, its higher suitability during the earlier phases of ideation and group development, and its perception by participants as something “framed.” Through this, we highlight the underexplored potential of using physical, offline resources as a means to solve difficulties in distanced social interactions. 相似文献
83.
James M. Chappell Azhar Iqbal M. A. Lohe Lorenz von Smekal Derek Abbott 《Quantum Information Processing》2013,12(4):1719-1735
The Grover search algorithm is one of the two key algorithms in the field of quantum computing, and hence it is desirable to represent it in the simplest and most intuitive formalism possible. We show firstly, that Clifford’s geometric algebra, provides a significantly simpler representation than the conventional bra-ket notation, and secondly, that the basis defined by the states of maximum and minimum weight in the Grover search space, allows a simple visualization of the Grover search analogous to the precession of a spin- ${\frac{1}{2}}$ particle. Using this formalism we efficiently solve the exact search problem, as well as easily representing more general search situations. We do not claim the development of an improved algorithm, but show in a tutorial paper that geometric algebra provides extremely compact and elegant expressions with improved clarity for the Grover search algorithm. Being a key algorithm in quantum computing and one of the most studied, it forms an ideal basis for a tutorial on how to elucidate quantum operations in terms of geometric algebra—this is then of interest in extending the applicability of geometric algebra to more complicated problems in fields of quantum computing, quantum decision theory, and quantum information. 相似文献
84.
We present a new, real‐time method for rendering soft shadows from large light sources or lighting environments on dynamic height fields. The method first computes a horizon map for a set of azimuthal directions. To reduce sampling, we compute a multi‐resolution pyramid on the height field. Coarser pyramid levels are indexed as the distance from caster to receiver increases. For every receiver point and every azimuthal direction, a smooth function of blocking angle in terms of log distance is reconstructed from a height difference sample at each pyramid level. This function's maximum approximates the horizon angle. We then sum visibility at each receiver point over wedges determined by successive pairs of horizon angles. Each wedge represents a linear transition in blocking angle over its azimuthal extent. It is precomputed in the order‐4 spherical harmonic (SH) basis, for a canonical azimuthal origin and fixed extent, resulting in a 2D table. The SH triple product of 16D vectors representing lighting, total visibility, and diffuse reflectance then yields the soft‐shadowed result. Two types of light sources are considered; both are distant and low‐frequency. Environmental lights require visibility sampling around the complete 360 ° azimuth, while key lights sample visibility within a partial swath. Restricting the swath concentrates samples where the light comes from (e.g. 3 azimuthal directions vs. 16‐32 for a full swath) and obtains sharper shadows. Our GPU implementation handles height fields up to 1024 × 1024 in real‐time. The computation is simple, local, and parallel, with performance independent of geometric content. 相似文献
85.
Derek A. Paley Naomi Ehrich Leonard Rodolphe Sepulchre 《Systems & Control Letters》2008,57(3):209-215
We provide a cooperative control algorithm to stabilize symmetric formations to motion around closed curves suitable for mobile sensor networks. This work extends previous results for stabilization of symmetric circular formations. We study a planar particle model with decentralized steering control subject to limited communication. Because of their unique spectral properties, the Laplacian matrices of circulant graphs play a key role. We illustrate the result for a skewed superellipse, which is a type of curve that includes circles, ellipses, and rounded parallelograms. 相似文献
86.
Mark Voigtmann 《软件》2009,(1):4-4
对于一名为自动化公司提供咨询的律师来说,一件让人很不爽的事情就是有时候摆在我面前的事情是如此之多。下面是一个例子:比方说控制工程有限公司(Control Engineers Limited,CEL)希望让我就一个新项目提供一些法律意见。出现在我的收件箱中的是一份来自于CEL的客户的小礼物.其中包括一份40页的“一般条件说明”.一份5页的“特殊情况说明”.一些令人生畏的规格.以及一份打印精美的采购合同。 相似文献
87.
Derek Lea 《计算机光盘软件与应用》2008,(2):94-97
智能对象的出现使得在Photoshop和Illustrator中使用像素和矢量之间的差别迅速消失。Derek Lea将会在制作一个结构完美且矢量明显的作品的同时为你解释原因。 相似文献
88.
Derek Hull 《International Journal of Fracture》1994,70(1):59-79
A modification of Sommer's classical experiment [4] has been used to fracture rods of a brittle epoxy resin in mixed mode I/III stress conditions. The nucleation and growth of cracks in an increasing K
III/K
I stress field have been investigated, particularly in relation to the formation of river lines and the evolution of multiple cracks between river lines to form smooth helicoid surfaces. The fractographic features associated with the progressive development of river line patterns involving crack bowing at river line steps, interaction between arrays of cracks and the coalescence of river lines are described. As K
III/K
I increases the scale of the river line patterns increases but the patterns remain self similar. Using principles from differential geometry it is shown that helicoid surfaces can be generated entirely by crack evolution involving tilting without twiting.Emeritus Goldsmiths' Professor of Metallurgy, University of Cambridge, U.K. 相似文献
89.
In the present laser processing work, the powder injection technique was investigated as a method for producing a surface metal matrix composite (MMC) containing large SiC particulates (SiCp) (105–150 m). This size is known to enhance the wear resistance of bulk aluminium-based composites. The effects of the laser-processing conditions, the powder feeding rate and the surface situations necessary to produce a well incorporated MMC on the surface were studied, and the microstructure examined. In previous work, laser processing involving the preplacement of SiCp was developed to create an AI-SiCp (45 m) MMC layer on aluminium alloy surfaces. Some of these ideas were used in conjunction with the injection process in the present work to enhance the surface-wear resistance. The wear resistance of an MMC obtained by a single laser track with the injection technique was determined and compared with the base alloy and the MMC layer produced by the preplacement technique. 相似文献
90.
This paper presents a novel method of nondestructively determining all nine elastic constants of fiber-reinforced orthotropic plate specimens. Group velocities of bulk quasi-longitudinal (QL), pure transverse (PT), and surface skimming pseudo-longitudinal modes are measured in glass-fiber (GF) and carbon-fiber (CF) reinforced Poly Ether Ether Ketone (PEEK) specimens by a point-source/point-receiver (PS/PR) technique. First, the pure index longitudinal moduliC
11,C
22, andC
33, are obtained from the longitudinal (L) group velocities measured in three principal directions. Next, the pure index shear moduli,C
44,C
55, andC
66, are determined by measuring the shear horizontally (SH) polarized PT group velocities in the symmetry planes. Finally, the mixed index elastic constantsC
ij
(i j) are calculated from QL group velocities measured in the symmetry planes and using analytic formulas. 相似文献