15445828
Analysis of a class of nonconforming finite elements for crystalline microstructures
An analysis is given for a class of nonconforming Lagrange-type finite elements which have been successfully utilized to approximate the solution of a variational problem modeling the deformation of martensitic crystals with microstructure. These elements were first proposed and analyzed in 1992 by Rannacher and Turek for the Stokes equation. Our analysis highlights the features of these elements which make them effective for the computation of microstructure. New results for superconvergence and numerical quadrature are also given.
1669054
Nonconforming finite element approximation of crystalline microstructure
We consider a class of nonconforming nite element approxima- tions of a simply laminated microstructure which minimizes the nonconvex variational problem for the deformation of martensitic crystals which can un- dergo either an orthorhombic to monoclinic (double well) or a cubic to tetrag- onal (triple well) transformation. We rst establish a series of error bounds in terms of elastic energies for the L 2 approximation of derivatives of the de- formation in the direction tangential to parallel layers of the laminate, for the L 2 approximation of the deformation, for the weak approximation of the de- formation gradient, for the approximation of volume fractions of deformation gradients, and for the approximation of nonlinear integrals of the deformation gradient. We then use these bounds to give corresponding convergence rates for quasi-optimal nite element approximations.
3584727
Simple offset assignment in presence of subword data
Many embedded architectures support indirect addressing mode with autoincrement/autodecrement. By maximizing the use of this mode, generation of explicit instructions for performing address arithmetic can be avoided and thus reductions in code size and improvements in performance are achieved. Bartley [2] and Liao et al. [16] developed a method for finding a storage layout for program variables so that the use of autoincrement/autodecrement could be maximized. They introduced the Simple Offset Assignment (SOA) problem and solved it using a Path Cover (PC) formulation.We observe that many media and network processing applications make extensive use of subword data. Therefore, for such applications, by packing multiple subword variables into a single word, we can generate storage layouts that further reduce the cost of address arithmetic in two ways. First the need for address arithmetic is reduced as variables that are packed together share the same address. Second opportunities for using autoincrement andautodecrement instructions are increased as layouts are now possible which place a variable adjacent to more than two variables. This approach has become feasible because of the recent trend in embedded processor design which allows subword variables that are packed together to be accessed and manipulated without incurring performance penalty. We introduce the SubWord Offset Assignment (SWOA) problem and solve it using a Path Cover with Node Coalescing (PCwNC) formulation. Node coalescing corresponds to packing of multiple subword variables into a single word while path covering corresponds to placement of variables in adjacent memory locations to enable the use of autoincrement/autodecrement. We present three heuristics to solve the PCwNC problem. Experiments show that when the program is optimized for code size, the three proposed algorithms achieve 26%, 26.9% and 32% reduction in the number of static explicit address arithmetic instructions over Liao et al.'s algorithm. The algorithms also achieve 14.5%, 22.1%and 22.7% reduction in stack frame size. If the program is optimized for performance, the algorithms achieve 24.3%, 24.7% and 30.2% reduction in the dynamic instruction count of explicit address arithmetic instructions.
34801552
Profile-based event tracking
In this research, we focus on tracking topics that originate and evolve from a specific event. Intuitively, a few key elements of a target event, such as date, location, and persons involved, would be enough for making a decision on whether a test story is on-topic. Consequently, a profile-based event tracking method is proposed. We attempt to build an event profile from the given on-topic stories by robust information retrieval technologies. A feature selection metric and a recognized event clause are utilized to determine most (if not all) key semantic elements of the target event. Preliminary experiments on the TDT2 mandarin corpus show that this profile-based event tracking method is promising.
12309193
Building a Chinese Shallow Parsed TreeBank for Collocation Extraction
To automatically extract Chinese collocations and build a large-scale collocation bank, we are developing a one-million-word Chinese shallow parsed treebank. The treebank can be used not only as a training set for our shallow parser, but also as processed data from which collocations are extracted. This paper presents several issues related to this on-going project, such as our definition of shallow parsing used in Chinese collocation extraction, guideline preparation, and quality control.
10610312
Semantic sports video analysis: approaches and new applications
In this paper, we show that event-based semantic analysis of sports video can be achieved through two major classes of methods: approaches using deterministic reasoning and approaches depending on probabilistic inference. Deterministic approaches depend on an explicit description of an event and an explicit representation of the event in terms of low-level aural-visual features that can be automatically detected. Probabilistic approaches are based on some proper state/transition models whose parameters are learnt through labeled training sequences. We first discuss the pros and cons of the two classes of approaches. Next, we present algorithms of these two types for a new application, automatic analysis of coaching video (which is different from sports broadcast programs that have been subject of most prior work).
1974741
Strategyproof Mechanisms towards Dynamic Topology Formation in Autonomous Networks
In autonomous networks, cooperations among nodes cannot be assumed, since each node is capable of making independent decisions based on their personal preferences. In particular, when a node needs the help of intermediate nodes to relay messages to other nodes, these intermediaries may be reluctant to contribute their network resource for the benefit of others. Ideally, the right amount of incentives should be provided to motivate cooperations among autonomous nodes so that a mutually beneficial network results. In this paper, we leverage the power of mechanism design in microeconomics to design a distributed incentive mechanism that motivates each node towards a more desirable network topology. Since network parameters and constraints change dynamically in reality, the desirable topology can vary over time. Our solution presented in this paper has successfully encompassed such a dynamic nature of the network topology. In addition, we have transformed our solution to an easy-to-implement distributed algorithm, that converges towards the globally optimal topology.