首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到10条相似文献,搜索用时 156 毫秒
1.
In this paper, we modify the mountain method and then create a modified mountain clustering algorithm. The proposed algorithm can automatically estimate the parameters in the modified mountain function in accordance with the structure of the data set based on the correlation self-comparison method. This algorithm can also estimate the number of clusters based on the proposed validity index. As a clustering tool to a grouped data set, the modified mountain algorithm becomes a new unsupervised approximate clustering method. Some examples are presented to demonstrate this algorithms simplicity and effectiveness and the computational complexity is also analyzed.  相似文献   

2.
CURE算法是一种凝聚的层次聚类算法,它首先提出了使用多代表点描述簇的思想。本文通过对已有的基于多代表点的层次聚类算法特点的分析,提出了一种新的基于多代表点的层次聚类算法WRPC。它使用了基于影响因子的簇代表点选取机制和基于k-近邻方法的小簇合并机制,可以发现形状、尺寸更为复杂的簇。实验结果表明,该算法在保证执行效率的情况下取得了更好的聚类效果。  相似文献   

3.
Experiment 1 explored the impact of physically touching a virtual object on how realistic the virtual environment (VE) seemed to the user. Subjects in a no touch group picked up a 3D virtual image of a kitchen plate in a VE, using a traditional 3D wand. See and touch subjects physically picked up a virtual plate possessing solidity and weight, using a technique called tactile augmentation. Afterwards, subjects made predictions about the properties of other virtual objects they saw but did not interact with in the VE. See and touch subjects predicted these objects would be more solid, heavier, and more likely to obey gravity than the no touch group. In Experiment 2 (a pilot study), subjects physically bit a chocolate bar in one condition, and imagined biting a chocolate bar in another condition. Subjects rated the event more fun and realistic when allowed to physically bite the chocolate bar. Results of the two experiments converge with a growing literature showing the value of adding physical qualities to virtual objects. This study is the first to empirically demonstrate the effectiveness of tactile augmentation as a simple, safe, inexpensive technique with large freedom of motion for adding physical texture, force feedback cues, smell and taste to virtual objects. Examples of practical applications are discussed.Based in part on Physically touching virtual objects using tactile augmentation enhances the realism of virtual environments' by Hunter Hoffman which appeared in the Proceedings of the IEEE Virtual Reality Annual International Symposium '98, Atlanta GA, pp 59–63. ¢ 1998 IEEE.  相似文献   

4.
A Writing Support Tool with Multiple Views   总被引:1,自引:0,他引:1  
This paper describes both SuperText,a computer program designed to support productiveexpository writing processes among students at adistance teaching university, and its theoreticaljustification. Being able to write well is animportant communication skill, and the writingprocess can help to build and clarify the writersknowledge. Computers can support this by providing amedium to externalise and record the writersunderstanding. Representations appropriate to thisexternalisation are uninstantiated idea labels,instantiated text units, and a variety ofrelationships between these items. SuperText usesthese representations to support a range of writingstyles. It provides several independent Views thatrepresent the structure of the evolving documentthrough expanding hierarchies, each with a varietyof Presentations. Allied to these Views is a textwork space providing access to a database ofcontinuous text nodes. Taken together, these providean ability to represent global and intermediatestructures of the document well beyond that ofconventional editors. These aspects were all ratedhighly by students participating in a series offield trials of SuperText.  相似文献   

5.
Boolean and Cartesian abstraction for model checking C programs   总被引:1,自引:1,他引:0  
We show how to attack the problem of model checking a C program with recursive procedures using an abstraction that we formally define as the composition of the Boolean and the Cartesian abstractions. It is implemented through a source-to-source transformation into a Boolean C program; we give an algorithm to compute the transformation with a cost that is exponential in its theoretical worst-case complexity but feasible in practice.  相似文献   

6.
The solution of an optimum problem of scheduling with n workpieces and m machine tools represents an optimum schedule of putting pieces on machines. In turn, the schedule is defined by an optimum collection of m permutations out of n objects, i.e., the vector permutation = (1, ..., m ), where each permutation i (1 i m) points up the sequence of working of all pieces on the ith machine. In this case, to each admissible schedule there must correspond an integral point from the m-dimensional Euclidean space of permutations (or, which is practically the same, the permutation out of numbers {1, 2, ..., mn}. In an effort to seek an optimum schedule, use is made of the notion of a metric space in the set of admissible schedules and the justified methodology of the search for an optimum schedule. A few metric spaces are described and analyzed and their comparative effectiveness is investigated for the solution of a different-route problem of scheduling.  相似文献   

7.
In this paper we deepen Mundici's analysis on reducibility of the decision problem from infinite-valued ukasiewicz logic to a suitable m-valued ukasiewicz logic m , where m only depends on the length of the formulas to be proved. Using geometrical arguments we find a better upper bound for the least integer m such that a formula is valid in if and only if it is also valid in m. We also reduce the notion of logical consequence in to the same notion in a suitable finite set of finite-valued ukasiewicz logics. Finally, we define an analytic and internal sequent calculus for infinite-valued ukasiewicz logic.  相似文献   

8.
We show that a few simple search strategies can solve a variety of difficult puzzles ranging from the 15-puzzle to central solitaire, Rubiks cube, and several of its variants. One of these strategies automatically generates subgoals; another finds efficient sets of rules for the subgoals. The subgoals are based on the reversal of simple logical implications. With these strategies and a simple learning algorithm, we not only solve particular instances of these problems but automatically generate programs that solve all instances of the problem with reasonable efficiency. Our automatically generated program for Rubiks cube can solve a fully scrambled cube in about two minutes on a 66 Mhz 486 PC.  相似文献   

9.
Clustering is a powerful machine learning technique that groups “similar” data points based on their characteristics. Many clustering algorithms work by approximating the minimization of an objective function, namely the sum of within-the-cluster distances between points. The straightforward approach involves examining all the possible assignments of points to each of the clusters. This approach guarantees the solution will be a global minimum; however, the number of possible assignments scales quickly with the number of data points and becomes computationally intractable even for very small datasets. In order to circumvent this issue, cost function minima are found using popular local search-based heuristic approaches such as k-means and hierarchical clustering. Due to their greedy nature, such techniques do not guarantee that a global minimum will be found and can lead to sub-optimal clustering assignments. Other classes of global search-based techniques, such as simulated annealing, tabu search, and genetic algorithms, may offer better quality results but can be too time-consuming to implement. In this work, we describe how quantum annealing can be used to carry out clustering. We map the clustering objective to a quadratic binary optimization problem and discuss two clustering algorithms which are then implemented on commercially available quantum annealing hardware, as well as on a purely classical solver “qbsolv.” The first algorithm assigns N data points to K clusters, and the second one can be used to perform binary clustering in a hierarchical manner. We present our results in the form of benchmarks against well-known k-means clustering and discuss the advantages and disadvantages of the proposed techniques.  相似文献   

10.
We provide a concept combining techniques known from geometric multigrid methods for saddle point problems (such as smoothing iterations of Braess- or Vanka-type) and from algebraic multigrid (AMG) methods for scalar problems (such as the construction of coarse levels) to a coupled algebraic multigrid solver. Coupled here is meant in contrast to methods, where pressure and velocity equations are iteratively decoupled (pressure correction methods) and standard AMG is used for the solution of the resulting scalar problems. To prove the efficiency of our solver experimentally, it is applied to finite element discretizations of real life industrial problems.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号