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排序方式: 共有770条查询结果,搜索用时 218 毫秒
11.
Dimitris Giakoumis Nikolaos Kaklanis Konstantinos Votis Dimitrios Tzovaras 《Universal Access in the Information Society》2014,13(2):227-248
His paper presents a tool facilitating developers of user interfaces (UIs) to experience accessibility limitations that can be posed from various disabilities during the interaction of impaired users with their developments. In this respect, various aspects of visual, hearing, physical and cognitive impairments have been modelled through filters providing approximate, yet, realistic simulations over them. These filters have formed the basis for the developed tool, which can be used either on its own (as a standalone application), or be embedded in the NetBeans Integrated Development Environment. The tool, named DIAS, allows for impairment simulations to be performed over Java, mobile and web applications. Moreover, it integrates two of the most common assistive technologies (ATs), namely a screen reader and a magnifier. As a result, developers of UIs can not only experience how interaction would be affected from various impairments, but they can also understand how their developments would be perceived by impaired users through an AT. This work aims to provide an integrated, practical solution for impairment simulation, which could be easily adopted by developers, thus realistically increasing the possibilities for the future development of interactive applications that are more accessible to users with disabilities. 相似文献
12.
Measurements have been carried out in the developing and fully developed regions of a free, axisymmetric, isothermal, air-water, bubbly jet. Three experiments have been conducted at a fixed jet-exit Reynolds number and gas superficial velocity using three different bubble injector assemblies producing bubbles of moderately different average sizes and size distributions. The volume fraction of the bubbly jet flow examined in this study is low and the resulting dispersed flow is dilute. A one-component Phase-Doppler Velocimetry system has been employed to measure bubble size and velocity non-intrusively. Visual data collected simultaneously with the light-scattering measurements were analyzed with the aid of image processing and used to verify the trends portrayed by the light-scattering measurements and to determine average bubble size. Our measurements show that, even in the dilute flow examined here, differences in initial bubble-size and size distribution can influence the RMS velocity fluctuations of the bubbles, particularly in the jet development region. The average bubble velocities are less sensitive. Evidence that the development pattern of the jet near the exit is affected by the presence of the bubbles is also presented. Near the exit of the jet, bubbles are shown to be ejected laterally outside the jet due to the significant lift force caused by the high velocity gradient in the axisymmetric shear layer. The observed sensitivity of the bubble flow to size-related parameters and initial conditions in this dilute case, indicates that discrepancies in previous measurements of dispersed, bubbly flows could be attributed to different size characteristics and/or initial conditions. 相似文献
13.
Athanasios N. Fatsikostas Dimitris. I. Kondarides Xenophon E. Verykios 《Catalysis Today》2002,75(1-4):145-155
The reformation of biomass-derived ethanol to a hydrogen-rich gas stream suitable for feeding fuel cells is investigated as an efficient and environmentally friendly process for the production of electricity for mobile and stationary applications. Steam reforming of ethanol is investigated over Ni catalysts supported on La2O3, Al2O3, YSZ and MgO. The influence of several parameters on the catalytic activity and selectivity is examined including reaction temperature, water-to-ethanol ratio and space velocity. Results reveal that the Ni/La2O3 catalyst exhibits high activity and selectivity toward hydrogen production and, most important, long term stability for steam reforming of ethanol. The enhanced stability of this catalyst may be due to scavenging of coke deposition on the Ni surface by lanthanum oxycarbonate species which exist on top of the Ni particles under reaction conditions. 相似文献
14.
Summary This paper describes the synthesis and characterization of poly{3-[4-cyano-4-biphenyl)oxy]propyl vinyl ether} [poly(6-3)] macromonomers obtained by the functionalization of the growing chain end of the corresponding living polymer obtained by the initiation of the cationic polymerization of 3-[4-cyano-4-biphenyl)oxy]propyl vinyl ether with CF3SO3H/S(CH3)2, with 2-hydroxy ethyl methacrylate [poly(6-3)-I], 2-[2-(2-allyloxyethoxy)ethoxy]ethanol [poly(6-3)-II] and 10-undecen-1-ol [poly(6-3)-III].Part 20: V. Percec and M. Lee, J. Mater. Chem., submitted 相似文献
15.
This work introduces decentralized query processing techniques based on MIDAS, a novel distributed multidimensional index. In particular, MIDAS implements a distributed k-d tree, where leaves correspond to peers, and internal nodes dictate message routing. MIDAS requires that peers maintain little network information, and features mechanisms that support fault tolerance and load balancing. The proposed algorithms process point and range queries over the multidimensional indexed space in only O(log n) hops in expectance, where n is the network size. For nearest neighbor queries, two processing alternatives are discussed. The first, termed eager processing, has low latency (expected value of O(log n) hops) but may involve a large number of peers. The second, termed iterative processing, has higher latency (expected value of O(log2 n) hops) but involves far fewer peers. A detailed experimental evaluation demonstrates that our query processing techniques outperform existing methods for settings involving real spatial data as well as in the case of high dimensional synthetic data. 相似文献
16.
On the Competitive Ratio for Online Facility Location 总被引:2,自引:0,他引:2
Dimitris Fotakis 《Algorithmica》2008,50(1):1-57
We consider the problem of Online Facility Location, where the demand points arrive online and must be assigned irrevocably
to an open facility upon arrival. The objective is to minimize the sum of facility and assignment costs. We prove that the
competitive ratio for Online Facility Location is Θ
. On the negative side, we show that no randomized algorithm can achieve a competitive ratio better than Ω
against an oblivious adversary even if the demands lie on a line segment. On the positive side, we present a deterministic
algorithm which achieves a competitive ratio of
in every metric space.
A preliminary version of this work appeared in the Proceedings of the 30th International Colloquium on Automata, Languages
and Programming (ICALP 2003), Lecture Notes in Computer Science 2719. This work was done while the author was at the Max-Planck-Institut
für Informatik, Saarbrücken, Germany, and was partially supported by the Future and Emerging Technologies programme of the
EU under contract number IST-1999-14186 (ALCOM–FT). 相似文献
17.
Pavlopoulos John Kougia Vasiliki Androutsopoulos Ion Papamichail Dimitris 《Knowledge and Information Systems》2022,64(7):1691-1722
Knowledge and Information Systems - Diagnostic captioning (DC) concerns the automatic generation of a diagnostic text from a set of medical images of a patient collected during an examination. DC... 相似文献
18.
This paper presents an efficient dynamics-based computer animation system for simulating and controlling the motion of articulated figures. A non-trivial extension of Featherstone's O(n) recursive forward dynamics algorithm is derived which allows enforcing one or more constraints on the animated figures. We demonstrate how the constraint force evaluation algorithm we have developed makes it possible to simulate collisions between articulated figures, to compute the results of impulsive forces, to enforce joint limits, to model closed kinematic loops, and to robustly control motion at interactive rates. Particular care has been taken to make the algorithm not only fast, but also easy to implement and use. To better illustrate how the constraint force evaluation algorithm works, we provide pseudocode for its major components. Additionally, we analyze its computational complexity and finally we present examples demonstrating how our system has been used to generate interactive, physically correct complex motion with small user effort. 相似文献
19.
A Survey of Applications of Polyoxometalates 总被引:1,自引:0,他引:1
Katsoulis DE 《Chemical reviews》1998,98(1):359-388
20.
Dimitris Gizopoulos Dimitris Nikolos Antonis Paschalis Constantin Halatsis 《Journal of Electronic Testing》1996,8(3):241-260
In this paper the testability of modified-Booth array multipliers for standard cells based design environments is examined for first time. In such cases the structure of the cells may be unknown, thus Cell Fault Model (CFM) is adopted. Two C-testable designs are proposed. A design for an N
x × Ny bits modified-Booth multiplier, which uses ripple carry addition at the last stage of the multiplication, is first proposed. The design requires the addition of only one extra primary input and 38 test vectors with respect to CFM. A second C-testable design is given using carry lookahead addition at the last stage which is the case of practical implementations of modified-Booth multipliers. Such a C-testable design using carry lookahead addition is for first time proposed in the open literature. This second design requires the addition of 4 extra primary inputs. One-level and two-levels carry lookahead adders, are considered. The C-testable design requires 61 test vectors for the former and 73 test vectors for the latter, respectively. The hardware and delay overheads imposed by both C-testable designs are very small and decrease when the size of the multiplier increases. 相似文献