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51.
Few of the arguments deployed above have been either device dependent or application area dependent. Even if further discussion leads to a resolution of these and future issues differnt from the author's, the case is made that a Transformations chapter could be written which would be naturally included in most application-oriented 3D graphics standards.  相似文献   
52.
Error-correcting codes which are ideals in group rings where the underlying group is metacyclic and non-abelian are examined. Such a groupG(M, N,R) is the extension of a finite cyclic group M by a finite cyclic group N and has a presentation of the form (S, T:S M =1,T N =1, T· S=S R ·T) where gcd(M, R)=1, R N =1 modM, R 1. Group rings that are semi-simple, i.e., where the characteristic of the field does not divide the order of the group, are considered. In all cases, the field of the group ring is of characteristic 2, and the order ofG is odd.Algebraic analysis of the structure of the group ring yields a unique direct sum decomposition ofFG(M, N, R) to minimal two-sided ideals (central codes). In every case, such codes are found to be combinatorically equivalent to abelian codes and of minimum distance that is not particularly desirable. Certain minimal central codes decompose to a direct sum ofN minimal left ideals (left codes). This direct sum is not unique. A technique to vary the decomposition is described. p]Metacyclic codes that are one-sided ideals were found to display higher minimum distances than abelian codes of comparable length and dimension. In several cases, codes were found which have minimum distances equal to that of the best known linear block codes of the same length and dimension.  相似文献   
53.
The fuzzy c-means/ISODATA algorithm is usually described in terms of clustering a finite data set. An equivalent point of view is that the algorithm clusters the support points of a finite-support probability distribution. Motivated by recent work on the hard version of the algorithm, this paper extends the definition to arbitrary distributions and considers asymptotic properties. It is shown that fixed points of the algorithm are stationary points of the fuzzy objective functional, and vice versa. When the algorithm is iteratively applied to an initial prototype set, the sequence of prototype sets produced approaches the set of fixed points. If an unknown distribution is approximated by the empirical distribution of stationary, ergodic observations, then as the number of observations grows large, fixed points of the algorithm based on the empirical distribution approach fixed points of the algorithm based on the true distribution. Furthermore, with respect to minimizing the fuzzy objective functional, the algorithm based on the empirical distribution is asymptotically at least as good as the algorithm based on the true distribution.  相似文献   
54.
This paper proposes to investigate the potential benefit of the use of low-level human vision behaviors in the context of high-level semantic concept detection. A large part of the current approaches relies on the Bag-of-Words (BoW) model, which has proven itself to be a good choice especially for object recognition in images. Its extension from static images to video sequences exhibits some new problems to cope with, mainly the way to use the temporal information related to the concepts to detect (swimming, drinking...). In this study, we propose to apply a human retina model to preprocess video sequences before constructing the State-Of-The-Art BoW analysis. This preprocessing, designed in a way that enhances relevant information, increases the performance by introducing robustness to traditional image and video problems, such as luminance variation, shadows, compression artifacts and noise. Additionally, we propose a new segmentation method which enables a selection of low-level spatio-temporal potential areas of interest from the visual scene, without slowing the computation as much as a high-level saliency model would. These approaches are evaluated on the TrecVid 2010 and 2011 Semantic Indexing Task datasets, containing from 130 to 346 high-level semantic concepts. We also experiment with various parameter settings to check their effect on performance.  相似文献   
55.
Charge exchange and fragmentation are the usual results in ion-molecule collision systems, and the specifics of the fragmentation process determine the chemical destiny of the target system. In this paper, we report recent progress on calculations of the fragmentation patterns for the model system He2+ + H2O for projectile energies of a few keV. The calculations are obtained using the electron-nuclear dynamics (END) method for solution of the time-dependent Schrödinger equation.  相似文献   
56.
The effectiveness of one particular shrouded tool type in capturing composite dust generated during dry machining operations was tested. The effectiveness of the shrouded tool was measured by comparing exposures during identical operations done by the same workers. The operation was conducted by dividing the time into two equal portions, one using an unshrouded tool and the other with same tool shrouded. The operations included sanding and grinding operations of fibrous glass/epoxy composite materials. Unshrouded short-term exposures ranged from 2.17 mg/m3 to 50.81 mg/m3. There was a significant reduction in exposure using the shroud (paired t-test, p = 0.005). The effect of a shroud on respirable dust exposures was inconclusive, because of the limited amount of respirable dust collected in these short-term samples.  相似文献   
57.
This paper is an exposition of two methods of formulating a lower bound for the minimum distance of a code which is an ideal in an abelian group ring. The first, a generalization of the cyclic BCH (Bose-Chaudhuri-Hoquenghem) bound, was proposed by Camion [2]. The second method, presented by Jensen [4], allows the application of the BCH bound or any of its improvements by viewing an abelian code as a direct sum of concatenations of cyclic codes. This second method avoids the mathematical analysis required for a direct generalization of a cyclic bound to the abelian case. It can produce a lower bound that improves the generalized BCH bound. We present simple algorithms for 1) deriving the generalized BCH bound for an abelian code 2) determining direct sum decompositions of an abelian code to concatenated codes and 3) deriving a bound on an abelian code, viewed as a direct sum of concatenated codes, by applying the cyclic BCH bound to the inner and outer code of each concatenation. Finally, we point out the applicability of these methods to codes that are not ideals in abelian group rings.  相似文献   
58.
Some industries are very sensitive to electric power interruptions and voltage sags, which are a normal consequence of the utility fault-clearing process. Typically, US utilities will try once or twice to clear faults without blowing any tap fuses, which would require dispatching a trouble crew to replace. To reduce complaints and to improve power quality for critical customers with high economic impact of interruptions, some utilities have been eliminating fuse-saving practices on feeder breakers and reclosers. The impact on overall reliability and the number of interruptions is evaluated based on distribution feeder power quality data. Some degradation in overall reliability can be expected, but this can be minimized with judicious placement of line reclosers. Critical customers can expect a significant reduction in the number of interruptions. A value-based economic analysis, including both utility and customer costs, shows that the practice has a high overall benefit-to-cost ratio. The utility experiences increased costs, but these are frequently overshadowed by the potential customer savings. However, removing fast tripping may correct for only a small portion of the utility-related events that might disrupt sensitive industrial processes. This article analyzes the impacts of removing fast tripping on reliability indices and on power system economics  相似文献   
59.
60.
It has been recognized that crystal polymorphism is an important factor related to the physicochemical and biological properties of drug substances and formulations. In this work, the piroxicam polymorphic forms 1 and 2 were studied using near-infrared chemical imaging (NIR-CI) technology to map the distribution of both species in pharmaceutical formulations. In this direction, the partial least squares (PLS) method was used to construct calibration models of concentrations per pixel of the sample. The RMSEP results for both models of the polymorphic forms remained below 4% (w/w). It was also possible to distinguish local and global information of the constituents through this method. These results seem to be a suitable tool for quality process control and final product quality assurance.  相似文献   
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