赛灵思：重点领域让FPGA更光明

赛灵思（Xilinx）公司总裁兼CEO Moshe Gavrielov现在依然相信，FPGA应用将有许多机会在2009年得到增长。例如，无线基础设备制造商将会在2009年继续开发下一代无线服务设备。从全球角度来看，这就意味着制造商将继续采用FPGA开发创新的3GPPLTE（长期演进技术）和WiMax基站。对于中国来说，这意味着制造商将继续采用FPGA桔术开发创新的TD—SCDMA基站。     

TEG—a hybrid approach to information extraction

This paper describes a hybrid statistical and knowledge-based information extraction model, able to extract entities and relations at the sentence level. The model attempts to retain and improve the high accuracy levels of knowledge-based systems while drastically reducing the amount of manual labour by relying on statistics drawn from a training corpus. The implementation of the model, called TEG (trainable extraction grammar), can be adapted to any IE domain by writing a suitable set of rules in a SCFG (stochastic context-free grammar)-based extraction language and training them using an annotated corpus. The system does not contain any purely linguistic components, such as PoS tagger or shallow parser, but allows to using external linguistic components if necessary. We demonstrate the performance of the system on several named entity extraction and relation extraction tasks. The experiments show that our hybrid approach outperforms both purely statistical and purely knowledge-based systems, while requiring orders of magnitude less manual rule writing and smaller amounts of training data. We also demonstrate the robustness of our system under conditions of poor training-data quality. Ronen Feldman is a senior lecturer at the Mathematics and Computer Science Department of Bar-Ilan University in Israel, and the Director of the Data Mining Laboratory. He received his B.Sc. in Math, Physics and Computer Science from the Hebrew University, M.Sc. in Computer Science from Bar-Ilan University, and his Ph.D. in Computer Science from Cornell University in NY. He was an Adjunct Professor at NYU Stern Business School. He is the founder of ClearForest Corporation, a Boston based company specializing in development of text mining tools and applications. He has given more than 30 tutorials on next mining and information extraction and authored numerous papers on these topics. He is currently finishing his book “The Text Mining Handbook” to the published by Cambridge University Press. Benjamin Rosenfeld is a research scientist at ClearForest Corporation. He received his B.Sc. in Mathematics and Computer Science from Bar-Ilan University. He is the co-inventor of the DIAL information extraction language. Moshe Fresko is finalizing his Ph.D. in Computer Science Department at Bar-Ilan University in Israel. He received his B.Sc. in Computer Engineering from Bogazici University, Istanbul/Turkey on 1991, and M.Sc. on 1994. He is also an adjunct lecturer at the Computer Science Department of Bar-Ilan University and functions as the Information-Extraction Group Leader in the Data Mining Laboratory.     

Life-span development of visual working memory: When is feature binding difficult?

We asked whether the ability to keep in working memory the binding between a visual object and its spatial location changes with development across the life span more than memory for item information. Paired arrays of colored squares were identical or differed in the color of one square, and in the latter case, the changed color was unique on that trial (item change) or was duplicated elsewhere in the array (color-location binding change). Children (8-10 and 11-12 years old) and older adults (65-85 years old) showed deficits relative to young adults. These were only partly simulated by dividing attention in young adults. The older adults had an additional deficiency, specifically in binding information, which was evident only when item- and binding-change trials were mixed together. In that situation, the older adults often overlooked the more subtle, binding-type changes. Some working memory processes related to binding undergo life-span development in an inverted-U shape, whereas other, bias- and salience-related processes that influence the use of binding information seem to develop monotonically. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the Complexity of Verifying Concurrent Transition Systems

In implementation verification, we check that an implementation is correct with respect to a specification by checking whether the behaviors of a transition system that models the program's implementation correlate with the behaviors of a transition system that models its specification. In this paper, we investigate the effect of concurrency on the complexity of implementation verification. We consider trace-based and tree-based approaches to the verification of concurrent transition systems, with and without fairness. Our results show that in almost all cases the complexity of the problem is exponentially harder than that of the sequential case. Thus, as in the model-checking verification methodology, the state-explosion problem cannot be avoided.     

Correction of birefringence and thermal lensing in nonreciprocal resonators by use of a dynamic imaging mirror

Enhanced correction of thermally induced birefringence in the presence of strong single-pass, azimuthally dependent bipolar focusing was achieved in single-rod laser oscillators by use of an adaptive optic rear mirror with image relay and aberration correction capabilities. Together with a Faraday rotator, the imaging variable radius mirror was successfully tested in stable and unstable Nd:Cr:GSGG power oscillators under variable pump power conditions from 0 to 800 W. Birefringence correction in the absence of ray retracing was achieved.     

The influence of nonremembered affective associations on preference.

An important influence on our preference toward a specific object is its associations with affective information. Here, the authors concentrate on the role of memory on shaping such preferences. Specifically, the authors used a multistage behavioral paradigm that fostered associations between neutral shapes and affective images. Participants that explicitly remembered these affective associations preferred neutral shapes associated with positive images. Counterintuitively, participants who could not explicitly remember the associations preferred neutral shapes that were associated with negative images. Generally, the difference in preference between participants who could and could not remember the affective associations demonstrates a critical link between memory and preference formation. The authors propose that the preference for negatively associated items is a manifestation of a mechanism that produces an inherent incentive for rapidly assessing potentially threatening aspects in the environment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Determination of breakdown rates and defect densities in SiO2

Breakdowns in SiO₂ have been classified as defect related, due to wear-out and intrinsic. However, techniques to ascertain defect densities and breakdown rates at defects have not been available, nor has the distinction between wear-out and defect- related or intrinsic breakdowns been clearly demonstrated. A particular problem has been the inability to distinguish defect types, i.e. defects having different breakdown rates. Another source of confusion has been the tacit assumption that breakdown field histograms obtained from ramp breakdown tests are independent of the ramp rate, which cannot be valid for finite breakdown rates. We obtained relationships specifying the statistics of breakdown, including the effect of defects. These actually derive from results describing a Markov death process and depend on the time integrals of breakdown rates in defect-free regions and at defects and on parameters describing the defect distributions. For Poisson distributions of the defect, these parameters are the mean number of defects per device for each defect type. Any breakdown test is described by the same relations since the nature of the test enters only through the time integral of the breakdown rates. If a wear-out mechanism is operative, then the breakdown rates will depend on the time explicitly, i.e. not only via the time dependences of the applied field and temperature. procedures for obtaining defect densities and breakdown rates follow from the derived dependence on these quantities of the expectation value of the fraction of devices broken down. Ramp tests at various ramp rates are advantageous for this purpose. The field dependence of the breakdown rates can be extracted directly from the experimental data and no a priori form for this dependence need be assumed. Experimental results obtained from multiple ramp breakdown tests will be presented. The field dependence of the breakdown rates is found to vary significantly from a simple exponential dependence. Following Klein, the effect of fluctuations on the breakdown rates will be considered qualitatively to rationalize their observed field dependence. No explicit time dependence of the breakdown rates is indicated over the range of field covered by the data, implying the absence of wear-out.     

The effects of divided attention on encoding processes in memory: Mapping the locus of interference.

Despite the detrimental effects of divided attention at encoding on later memory performance, results described in the literature do not unequivocally specify which processes are interrupted during encoding by participants' occupation with a concurrent task. Using a processing analysis framework where the encoding process is viewed as a multiphase mental activity, the current research investigated this issue using a new differential temporal interference paradigm where the study phase of single words was interrupted at different temporal segments. In two experiments, we used performance on both memory and online choice reaction time tasks to assess whether such differential interference would produce different degrees of reduction in participants' later memory performance, as well as changes in the attentional resources required to execute each of the encoding phases. Measures of memory and concurrent task performance in the two experiments converged on similar patterns, showing that all phases of encoding are affected by the concurrent task. However, the initial encoding phase, which is tentatively associated with the initial registration of information, seems especially vulnerable to interference. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fracture analysis of materials with periodic microstructure by the representative cell method

The periodic structure of some natural and especially man-made materials can be manifested not only on an atomic but also on a larger scale. Investigation of mechanical properties of these materials usually hinges on well-developed homogenization methods. On the other hand, these methods are not suitable for fracture analysis where the knowledge of the local stress-strain fields near a flaw (a crack) is required. The result is obtained by the use of the representative cell method based on the discrete Fourier transform. This method enables one to determine the exact stress distribution in a periodic structure subjected to arbitrary loading. Direct application of the method is impossible since the crack violates the translational symmetry defined by the material microstructure. This obstacle is overcome by application of the fictitious loading to the uncracked body at the line where the crack is to be located. The amplitude of the loading is adjusted in order to fulfill the boundary conditions imposed on the crack faces. The compatibility equation for deriving this amplitude is obtained by the use of the corresponding Green function, which is found in a closed form. Fracture problems for the two types of materials with a periodic microstructure are considered. The first one is a composite material consisting of dissimilar isotropic elastic layers arranged periodically. The second periodic microstructure is a 2D infinite beam lattice modeling a cellular material. The analysis of the failure process in the latter case shows that in contrast to the case of homogeneous material, the crack propagation path is not defined by the condition of zero Mode II stress intensity factor.