Producing High‐Strength Metals by I‐ECAP

Incremental equal channel angular pressing (I‐ECAP) is used in this work to produce ultrafine‐grained (UFG) pure iron, aluminum alloy 5083, commercial purity titanium (grade 4), and magnesium alloy AZ31B. Pure iron is processed at room temperature, aluminum alloy at 200 °C, titanium at 320 °C, and magnesium alloy at 150 °C. Strength improvement, attributed to the grain refinement below 1 μm, is reported for all processed materials. The yield strength increase is the most apparent in pure iron, reaching almost 500 MPa after one pass of I‐ECAP, comparing to 180 MPa in the as‐forged conditions. UFG titanium, aluminum, and magnesium alloys obtained in this study reached yield stress of 800, 350, and 300 MPa, respectively, in each case exhibiting the yield strength increase by at least 30%, comparing to the alloys processed by conventional metal forming operations such as forging and rolling.     

Real-time object detection on CUDA

The aim of the research described in this article is to accelerate object detection in images and video sequences using graphics processors. It includes algorithmic modifications and adjustments of existing detectors, constructing variants of efficient implementations and evaluation comparing with efficient implementations on the CPUs. This article focuses on detection by statistical classifiers based on boosting. The implementation and the necessary algorithmic alterations are described, followed by experimental measurements of the created object detector and discussion of the results. The final solution outperforms the reference efficient CPU/SSE implementation, by approximately 6–8× for high-resolution videos using nVidia GeForce 9800GTX and Intel Core2 Duo E8200.     

Factorization of fuzzy concept lattices with hedges by modification of input data

We study the problem of reducing the size of fuzzy concept lattices with hedges by means of factorization. As it has been shown previously for the case of fuzzy concept lattices without hedges, the lattice computed by factorization of a fuzzy concept lattice is isomorphic to a fuzzy concept lattice of some other data table. This means that the factor concept lattice can be computed directly as a concept lattice, whose underlying data table is obtained by a modification of the original data table. There are two known types of such a modification: first, based on factorization of residuated lattices, and second, based on computation of shifted attributes. In this paper, we extend these results to a more general case of concept lattices with hedges.     

Blurred image restoration: A fast method of finding the motion length and angle

Motion blur in photographic images is a result of camera movement or shake. Methods such as Blind Deconvolution are used when information about the direction and size of blur is not known. Restoration methods, such as Lucy and Richardson or Wiener reconstruction use information about the direction and size of the blur in the deconvolution kernel (called Point Spread Function — PSF). Correct and fast determination of the direction and size of blur improves the quality of restoration and it can substantially reduce the computational time. In this article, a fast method for finding the direction and size of the blur automatically is presented. The method is based on computation of the power spectrum of the image gradient in the frequency domain. The method has achieved good results on both types of images: artificially blurred and naturally blurred (by the camera shake).     

Adolescents’ use of Instant Messaging as a means of emotional relief

Instant Messaging (IM) plays a major role in online communication, whether through dedicated software or through chat integrated in a social network’s platform. IM-based online conversation enables private, synchronous, interpersonal communication while being invisible and possibly anonymous; facilitates self-disclosure and intimacy; and possesses advantageous features of expressive writing and social support. For adolescents, the use of IM is a legitimate, available, and free alternative vehicle for communicating with peers to ventilate negative emotions and to receive social support and advice. The present study examined effects of IMing friends on the emotional state of distressed adolescents through both pre-post (n = 100) analyses and comparison with an un-distressed group (n = 50). Dependent measures included self-report questionnaires, textual analysis, and expert judges’ evaluations of the conversations. Findings revealed that IM conversation significantly contributed to the well-being of distressed adolescents. In addition, participants’ level of introversion–extroversion moderated the degree of their perceived emotional relief, so that introverted participants profited from IMing more than did extraverts. The implications of these findings are discussed in the context of online communication theory, as well as the practical implementations for troubled adolescents.     

Learning Vocabularies over a Fine Quantization

A novel similarity measure for bag-of-words type large scale image retrieval is presented. The similarity function is learned in an unsupervised manner, requires no extra space over the standard bag-of-words method and is more discriminative than both L2-based soft assignment and Hamming embedding. The novel similarity function achieves mean average precision that is superior to any result published in the literature on the standard Oxford 5k, Oxford 105k and Paris datasets/protocols. We study the effect of a fine quantization and very large vocabularies (up to 64 million words) and show that the performance of specific object retrieval increases with the size of the vocabulary. This observation is in contradiction with previously published results. We further demonstrate that the large vocabularies increase the speed of the tf-idf scoring step.     

Hand landmarks detection and localization in color images

This paper introduces a new method for detecting and localizing hand landmarks in 2D color images. Location of the hand landmarks is an important source of information for recognizing hand gestures, effectively exploited in a number of recent methods which operate from the depth maps. However, this problem has not yet been satisfactorily solved for 2D color images. Here, we propose to analyze the skin-presence masks, as well as the directional image of a hand using the distance transform and template matching. This makes it possible to detect the landmarks located both at the contour and inside the hand masks. Moreover, we performed an extensive experimental study to compare the proposed method with a number of state-of-the-art algorithms. The obtained quantitative and qualitative results clearly indicate that our approach outperforms other methods, which may help improve the existing gesture recognition systems.     

Boosting conditional probability estimators

In the standard agnostic multiclass model, <instance, label > pairs are sampled independently from some underlying distribution. This distribution induces a conditional probability over the labels given an instance, and our goal in this paper is to learn this conditional distribution. Since even unconditional densities are quite challenging to learn, we give our learner access to <instance, conditional distribution > pairs. Assuming a base learner oracle in this model, we might seek a boosting algorithm for constructing a strong learner. Unfortunately, without further assumptions, this is provably impossible. However, we give a new boosting algorithm that succeeds in the following sense: given a base learner guaranteed to achieve some average accuracy (i.e., risk), we efficiently construct a learner that achieves the same level of accuracy with arbitrarily high probability. We give generalization guarantees of several different kinds, including distribution-free accuracy and risk bounds. None of our estimates depend on the number of boosting rounds and some of them admit dimension-free formulations.     

预变形结合人工时效对Al-Mg-Si合金力学性能的影响

研究预变形结合人工时效处理对AA6060铝合金强度和韧性的影响。对经过均匀化热处理和挤压加工的AA6060铝合金进行固溶处理,然后对材料实施0-10%的预变形并再进行时效处理或者在人工时效过程中进行同步变形。通过对不同时效处理后的合金的显微硬度和拉伸性能分析,发现预变形对材料的时效行为和力学性能有显著影响,它可以使合金的时效速度明显加快。比较预变形和同步变形对人工时效的影响发现,同步变形结合人工时效可以使该合金在更短的时间内得到更好的力学性能。对两种变形对时效行为的影响机理进行了探讨。     

EnMS: early non-maxima suppression

Detection of objects in images using statistical classifiers is a well studied and documented technique. Different applications of such detectors often require selection of the image position with the highest response of the detector—they perform non-maxima suppression. This article introduces the concept of early non-maxima suppression, which aims to reduce necessary computations by making the non-maxima suppression decision early based on incomplete information provided by a partially evaluated classifier. We show that the error of one such speculative decision with respect to a decision made based on response of the complete classifier can be estimated by collecting statistics on unlabeled data. The article then considers a sequential strategy of multiple early non-maxima suppression tests which follows the structure of soft-cascade detectors commonly used for object detection. We also show that an optimal (fastest for requested error rate) suppression strategy can be created by a novel variant of Wald’s sequential probability ratio test (SPRT) which we call the conditioned SPRT (CSPRT). Experimental results show that the early non-maxima suppression significantly reduces amount of computation in the case of object localization while the error rates are limited to low predefined values. The proposed approach notably outperforms the state-of-the-art detectors based on WaldBoost. The potential applications of the early non-maxima suppression approach are not limited to object localization and could be applied wherever the goal is to find the strongest response of a classifier among a set of classified samples.