Frame-level temporal calibration of video sequences from unsynchronized cameras

This paper describes a method for temporally calibrating video sequences from unsynchronized cameras by image processing operations, and presents two search algorithms to match and align trajectories across different camera views. Existing multi-camera systems assume that input video sequences are synchronized either by genlock or by time stamp information and a centralized server. Yet, hardware-based synchronization increases installation cost. Hence, using image information is necessary to align frames from the cameras whose clocks are not synchronized. The system built for temporal calibration is composed of three modules: object tracking module, calibration data extraction module, and the search module. A robust and efficient search algorithm is introduced that recovers the frame offset by matching the trajectories in different views, and finding the most reliable match. Thanks to information obtained from multiple trajectories, this algorithm is robust to possible errors in background subtraction and location extraction. Moreover, the algorithm can handle very large frame offsets. A RANdom SAmple Consensus (RANSAC) based version of this search algorithm is also introduced. Results obtained with different video sequences are presented, which show the robustness of the algorithms in recovering various range of frame offsets for video sequences with varying levels of object activity.     

游戏是什么？

18年前,电子游戏是一个叫“小霸王”的红盒子,伴随着《魂斗罗》“上上下下左右左右BABA”按键下的30条命和《超级玛丽》踩乌龟得到的无数命,我们在懵懂之中第一次见到了那些叫做秘技的非热型性疑似Bug。于是．我们的童年开始与电视游戏密不可分。     

Negotiating SLAs-An Approach for a Generic Negotiation Framework for WS-Agreement

The current Web Services Agreement specification draft proposes a simple request-response protocol for agreement creation only addressing bilateral offer exchanges. This paper proposes a framework augmenting this WS-Agreement to enable negotiations according to a variety of bilateral and multilateral negotiation protocols. The framework design is based on a thorough analysis of taxonomies for negotiations from the literature in order to allow for capturing a variety of different negotiation models within a single, WS-Agreement compatible, framework. In order to provide for the intended flexibility, the proposed protocol takes a two-stage approach: a meta-protocol is conducted among interested parties to agree on a common negotiation protocol first before the real negotiation is carried out in the second step due to the protocol established in the first step.     

Flux creep and fishtail in melt-textured and single-crystalline YBa2Cu3O7

Time-dependent decay of the magnetic moment and magnetization measurements were used to study pinning and flux creep in two samples with and without aj(B) maximum in nonzero field (fishtail effect). From both measurements theE(j) relation was reconstructed forBc and the characteristic current exponent was obtained. At highj and lowB values are between 1 and 4; with increasingB passes a maximum and approaches negative values. At lowj is below 0.5 and not dependent onB orj. This behavior, which is qualitatively the same in both samples, is compared with proposed phase diagrams of the vortex lattice. Large values are correlated with the plateau of the normalized creep rateS 0.025; both observations indicate low relaxation and are found in that lowB region for whichj(B) has its minimum. This observation rejects a dominating influence of relaxation on the fishtail effect.     

Preparation,characterization and wear behaviour of TiNx-coated cermets obtained by plasma-enhanced chemical vapour deposition

Commercial cermet inserts were coated with titanium nitride by plasma-enhanced chemical vapour deposition (PECVD) using a pulsed direct current (d.c.) glow discharge. The influence of the coating parameters on the deposition rate, on the layer composition, on the layer-substrate interface, on the structure and on the microhardness of the layers was investigated for deposition temperatures in the range 500–700 °C. The adhesive strengths, and some mechanical properties, of the coated cermets were characterized by scratch tests, by friction wear investigations and by measurement of the transverse rupture strength. The wear behaviour was examined in the cutting tests. It was found that TiN _x -coatings deposited with a sufficiently high deposition rate and plasma power density have a low oxygen and chlorine content and that they are nearly stoichiometric. The layers usually have a columnar structure with a 200 texture. A granular, equiaxed structure was observed within a small range of deposition conditions. In interrupted and continuous turning tests with steel and grey cast iron, a high cutting performance of the coated inserts, which depended on the coating thickness and on the deposition temperature, was achieved.     

3D-Druck für Hochvakuumanwendungen

To mark our anniversary, we are presenting articles that have been particularly appreciated by readers of our online edition once again in print. Here: 3D-Printing for High Vacuum Applications 3D printing technology has made the leap from a home-based private practice to industrial manufacturing. Due to the increasing reliability of printers and increasing material diversity, especially in the metal sector, double-digit percentage growth rates are possible in the coming years. This thesis deals with the manufacture of parts made by 3D printing for high vacuum application. Different components are printed and examined for their vacuum compatibility. As shown furthermore, conventionally made standard components can be vacuum sealed to printed parts, which enables cost-effective production of more complex components, such as e.g. a vacuum chamber allows. In addition, functional components can already be realized in the manufacturing process. The integration of a system of flow channels directly into the wall of a chamber is just one example. Thus, such a chamber can be heated during evacuation and effectively cool in later operation.     

Upper limit ofTc for the copper oxides

The value of the critical temperature of the cuprates correlates with the doping level and is affected by the interplay of two competing factors: (1) the increase in carrier concentration, and (2) the pair-breaking effect of magnetic impurities. An analysis of the temperature dependence of the critical field leads to the conclusion that magnetic impurities are present even in a sample with the maximum observed value ofT _c.A new parameter, intrinsicT _c (T _cintr), which is its value in the absence of magnetic impurities, is introduced. The maximum value ofT _cintr, which corresponds to the maximum doping level, appears to be similar for different cuprates and to be equal to 160–170 K. This is the upper limit ofT _c in the cuprates.     

From monolithic to component-based performance evaluation of software architectures

Model-based performance evaluation methods for software architectures can help architects to assess design alternatives and save costs for late life-cycle performance fixes. A recent trend is component-based performance modelling, which aims at creating reusable performance models; a number of such methods have been proposed during the last decade. Their accuracy and the needed effort for modelling are heavily influenced by human factors, which are so far hardly understood empirically. Do component-based methods allow to make performance predictions with a comparable accuracy while saving effort in a reuse scenario? We examined three monolithic methods (SPE, umlPSI, Capacity Planning (CP)) and one component-based performance evaluation method (PCM) with regard to their accuracy and effort from the viewpoint of method users. We conducted a series of three experiments (with different levels of control) involving 47 computer science students. In the first experiment, we compared the applicability of the monolithic methods in order to choose one of them for comparison. In the second experiment, we compared the accuracy and effort of this monolithic and the component-based method for the model creation case. In the third, we studied the effort reduction from reusing component-based models. Data were collected based on the resulting artefacts, questionnaires and screen recording. They were analysed using hypothesis testing, linear models, and analysis of variance. For the monolithic methods, we found that using SPE and CP resulted in accurate predictions, while umlPSI produced over-estimates. Comparing the component-based method PCM with SPE, we found that creating reusable models using PCM takes more (but not drastically more) time than using SPE and that participants can create accurate models with both techniques. Finally, we found that reusing PCM models can save time, because effort to reuse can be explained by a model that is independent of the inner complexity of a component. The tasks performed in our experiments reflect only a subset of the actual activities when applying model-based performance evaluation methods in a software development process. Our results indicate that sufficient prediction accuracy can be achieved with both monolithic and component-based methods, and that the higher effort for component-based performance modelling will indeed pay off when the component models incorporate and hide a sufficient amount of complexity.