Nonchronological video synopsis and indexing

The amount of captured video is growing with the increased numbers of video cameras, especially the increase of millions of surveillance cameras that operate 24 hours a day. Since video browsing and retrieval is time consuming, most captured video is never watched or examined. Video synopsis is an effective tool for browsing and indexing of such a video. It provides a short video representation, while preserving the essential activities of the original video. The activity in the video is condensed into a shorter period by simultaneously showing multiple activities, even when they originally occurred at different times. The synopsis video is also an index into the original video by pointing to the original time of each activity. Video Synopsis can be applied to create a synopsis of an endless video streams, as generated by webcams and by surveillance cameras. It can address queries like "Show in one minute the synopsis of this camera broadcast during the past day'. This process includes two major phases: (i) An online conversion of the endless video stream into a database of objects and activities (rather than frames). (ii) A response phase, generating the video synopsis as a response to the user's query.     

Minimal Aspect Distortion (MAD) Mosaicing of Long Scenes

Long scenes can be imaged by mosaicing multiple images from cameras scanning the scene. We address the case of a video camera scanning a scene while moving in a long path, e.g. scanning a city street from a driving car, or scanning a terrain from a low flying aircraft. A robust approach to this task is presented, which is applied successfully to sequences having thousands of frames even when using a hand-held camera. Examples are given on a few challenging sequences. The proposed system consists of two components: (i) Motion and depth computation. (ii) Mosaic rendering. In the first part a “direct” method is presented for computing motion and dense depth. Robustness of motion computation has been increased by limiting the motion model for the scanning camera. An iterative graph-cuts approach, with planar labels and a flexible similarity measure, allows the computation of a dense depth for the entire sequence. In the second part a new minimal aspect distortion (MAD) mosaicing uses depth to minimize the geometrical distortions of long panoramic images. In addition to MAD mosaicing, interactive visualization using X-Slits is also demonstrated. This research was supported by the Israel Science Foundation. Video examples and high resolution images can be viewed in .     

Landscape and water in the oases of Egypt's western desert

While natural processes, mainly wind and water erosion, define desert landscapes, human manipulation and use of water play important roles in defining the landscape within desert oases. The role of water in the oases of the Western Desert of Egypt is described, and it is considered how the scarcity of water affects its use. The challenge to the protection of these archetypal landscapes presented by new forms of development is identified.     

GPGPU test suite minimisation: search based software engineering performance improvement using graphics cards

It has often been claimed that SBSE uses so-called ‘embarrassingly parallel’ algorithms that will imbue SBSE applications with easy routes to dramatic performance improvements. However, despite recent advances in multicore computation, this claim remains largely theoretical; there are few reports of performance improvements using multicore SBSE. This paper shows how inexpensive General Purpose computing on Graphical Processing Units (GPGPU) can be used to massively parallelise suitably adapted SBSE algorithms, thereby making progress towards cheap, easy and useful SBSE parallelism. The paper presents results for three different algorithms: NSGA2, SPEA2, and the Two Archive Evolutionary Algorithm, all three of which are adapted for multi-objective regression test selection and minimization. The results show that all three algorithms achieved performance improvements up to 25 times, using widely available standard GPUs. We also found that the speed-up was observed to be statistically strongly correlated to the size of the problem instance; as the problem gets harder the performance improvements also get better.     

Distilling the wisdom of crowds: weighted aggregation of decisions on multiple issues

Given the judgments of multiple voters regarding some issue, it is generally assumed that the best way to arrive at some collective judgment is by following the majority. We consider here the now common case in which each voter expresses some (binary) judgment regarding each of a multiplicity of independent issues and assume that each voter has some fixed (unknown) probability of making a correct judgment for any given issue. We leverage the fact that multiple votes by each voter are known in order to demonstrate, both analytically and empirically, that a method based on maximum likelihood estimation is superior to the simple majority rule for arriving at true collective judgments.     

Out-of-plane shear of fiber composites at moderate stretch levels

The response of incompressible fiber composites to moderate levels of out-of-plane shear and tension along the fibers is examined. It is assumed that the phases’ constitutive behaviors depend on the first invariant of the right Cauchy–Green deformation tensor, and in the vicinity of the reference configuration can be approximated by a two-terms Taylor series in this invariant. A deformation field satisfying an appropriate boundary conditions on a representative cylindrical composite element is proposed, and the resulting equilibrium equations are expanded in terms of a series. A solution, which is exact to second order in the deformation, is determined. This solution provides accurate estimates for the local fields developing in a cylindrical composite with Gent phases up to one third of the locking stretch ratio. The overall response predicted by this approximated quadratic solution is found to be in agreement with corresponding results for fiber composites with Gent phases that were determined by application of a new variational procedure and by finite-element simulation of a periodic composite.     

Microstructural evolution during the infiltration of boron carbide with molten silicon

The previously reported model that accounts for the formation of the core-rim structure in reaction-bonded boron carbide composites (RBBC) is expanded and validated by additional experimental observations and by a thermodynamic analysis of the ternary B–C–Si system. The microstructure of the RBBC composites consists of boron carbide particles with a core-rim structure, β-SiC and some residual silicon. The SiC carbide particles have a polygonal shape in composites fabricated in the presence of free carbon, in contrast to the plate-like morphology when the initial boron carbide is the sole source of carbon. In the course of the infiltration process, the original B₄C particles dissolve partly or fully in molten silicon, and a local equilibrium is established between boron carbide, molten silicon and SiC. Overall equilibrium in the system is achieved as a result of the precipitation of the ternary boron carbide phase B₁₂(B,C,Si)₃ at the surface of the original boron carbide particles and leads to the formation of the rim regions. This feature is well accounted for by the “stoichiometric saturation” approach, which takes into account the congruent dissolution of B₄C particles. The SiC phase, which precipitates form the silicon melt adopts the β-allotropic structure and grows preferably as single plate-like particles with an {1 1 1}_β habit plane. The morphology of the SiC particles is determined by the amount of carbon available for their formation.     

Dissolution kinetics and solubility limit of CaF2 in molten KCl–NaCl salt

The interaction between NaCl–KCl salt of an equimolar composition and CaF₂ was investigated in the 1023–1123 K temperature range. The solubility limit was determined as 2.1, 2.5, and 3.4 mol.% for 1023, 1073, and 1123 K, respectively. The linear dependence of the specific weight loss with time and the activation energy of the dissolution (124.6 ± 8.7 kJ/mol) indicate that CaF₂ dissociation of the ions is the limiting stage of the process. Thermodynamic properties (partial enthalpy and entropy) of CaF₂ in a dilute ternary –NaCl–KCl–CaF₂ liquid solution were estimated using the values of the solubility limit and by applying a regular solution approach.