Compression

Pour la fabrication des mousses polyuréthanes d'une certaine densité et d'une bonne qualité, on cherche donc à contrôler le mieux possible la formation de cette microstructure de sorte que le produit final ait les propriétés souhaitées pour l'application aux projectiles non létaux ce qui  nécessite le développement de stratégies de protection, donc c’est un enjeu non seulement scientifique mais également économique et social car au capital perdu s’ajoute la perte de vie humaine. Au niveau du laboratoire c’est ce qu’on cherche à atteindre une résistance au choc. Ce travail a pour objectif une élaboration et une détermination des caractéristiques mécaniques ainsi que l’évaluation du comportement balistique des matériaux mousses polyuréthanes élaborés par la formulation optimale, la caractérisation mécanique quasi-statique par essais de compression comporte une série d’essais accompagnés avec l’application à des projectiles non létaux. L’objectif est d’améliorer les propriétés physicochimiques, mécaniques très intéressantes notamment l’absorption des vibrations, résistance au choc.

The present paper deals with an experimental convective heat transfer investigation around a film-cooled, high-pressure gas turbine rotor blade mounted in a stationary, linear cascade arrangement. The measurements were performed in the von Karman Institute Isentropic Light Piston Compression Tube facility. The test blade was made of Macor glass ceramic and was instrumented with thin film gages. The coolant flow was ejected simultaneously through the leading edge (three rows of holes), the suction side (two rows of holes), and the pressure side (one row of holes). The effects of overall mass weight ratio, coolant to free-stream temperature ratio, and free-stream turbulence were successively investigated.

Expanded polystyrene (EPS) geofoam seismic buffers can be used to reduce earthquake-induced loads acting on rigid retaining wall structures. A numerical study was carried out to investigate the influence of wall height; EPS geofoam type, thickness, and stiffness; and excitation record on seismic buffer performance. The numerical simulations were carried out using a verified FLAC code. The influence of parameter values was examined by computing the maximum forces on the walls, the buffer compressive strains, and the relative efficiency of the buffer system. In general, the closer the predominant frequency of excitation to the fundamental frequency of the wall model, the greater the seismic loads and buffer compression. The choice of earthquake record is shown to affect the magnitude of maximum earth force and isolation efficiency. However, when the wall response for walls 3 to 9 m in height are presented in this study in terms of isolation efficiency, the data from scaled accelerogra...

In this paper a wavelet-based steganographic method is proposed for robust short-message hiding. The message is embedded into the most significant wavelet coefficients of a cover image to provide invisibility and resistance against lossy transmission over cellular networks, compression or other distortion. The architecture consists of three modules. In the first module the initial message is enciphered by an encryption

Data stored in databases keep growing as a result of businesses requirements for more information. A big portion of the cost of keeping large amounts of data is in the cost of disk systems, and the resources utilized in managing that data. This paper introduces various compression techniques for data stored in row oriented as well as column-oriented databases. Keeping

After collecting a data base of fingerprint images, we design a neural network algorithm for fingerprint recognition. When presented with a pair of fingerprint images, the algorithm outputs an estimate of the probability that the two images originate from the same finger. In one experiment, the neural network is trained using a few hundred pairs of images and its performance is subsequently tested using several thousand pairs of images originated from a subset of the database corresponding to 20 individuals. The error rate currently achieved is less than 0.5%. Additional results, extensions, and possible applications are also briefly discussed.

CNG and compressed hydrogen are compared to illustrate why CNG, but not compressed hydrogen, is a viable alternative vehicle fuel. It is shown that natural gas has a greater energy content per mole than hydrogen and that more moles of natural gas than hydrogen may be stored in a given volume under identical conditions. Natural gas stored at 20.78 MPa (3000 psig) and 21.1°C (70°F) contains five times as much energy as hydrogen stored under the same conditions. Natural gas stored in a representative size CNG cylinder provides a range of about 100 km, while hydrogen in the same cylinder would provide a range of only 26 km, even assuming 30% greater efficiency from the hydrogen-fueled engine.

The influence of steel and polypropylene fibers on the resistance to compression of concrete is evaluated. NTP 339.034 and ASTM C39 were used to test compressive strength in four groups with a total of 48 specimens distributed in a control group and three experimental groups during 14 and 28 days of curing. The compressive strength test was determined for an average compressive strength of f´cr = 294 kg/cm 2 (28.8 MPa), according to E 060 reinforced concrete standard. Group G1 presented a dosification of steel and polypropylene fibers of 10% by 25 kg/m 3 and 600 gr/m 3 , group G2 15% by 25 kg/m 3 and 600 gr/m 3 , group G3 20% by 25kg/m 3 and 600 gr/m 3 and G4 was not supplied with steel and polypropylene fibers. The specimens were subjected to compression tests at the age of 14 and 28 days,obtaining as a result that the most favorable group is the G3 group with a resistance of 322.98 kg/m 2 (31.67 MPa), exceeding the control group by 8.10%. It is evident that the presence of steel and polypropylene fibers in concrete significantly increase its resistance to compression.

It's a fact that nonlinear color models like Hue-Saturation -Value/ Brightness/ Luminance/ Intensity (HSV/ HSB/ HSL/ HSI) have special feature for each
channel. So in this paper we propose a new hybrid compression system that deals with each channel with a suitable compression technique to obtain encoded images with less size and high decoding quality than the traditional encoding methods.

Autoencoders play a fundamental role in unsupervised learning and in deep architectures for transfer learning and other tasks. In spite of their fundamental role, only linear autoencoders over the real numbers have been solved analytically. Here we present a general mathematical framework for the study of both linear and non-linear autoencoders. The framework allows one to derive an analytical treatment for the most non-linear autoencoder, the Boolean autoencoder. Learning in the Boolean autoencoder is equivalent to a clustering problem that can be solved in polynomial time when the number of clusters is small and becomes NP complete when the number of clusters is large. The framework sheds light on the different kinds of autoencoders, their learning complexity, their horizontal and vertical composability in deep architectures, their critical points, and their fundamental connections to clustering, Hebbian learning, and information theory.

The cyber world is an ever-changing world, cyber security is most importance and touches the lives of everyone on the cyber world including: Researchers, students, businesses, academia, and novice user. The paper suggests a body of knowledge that incorporate the view of academia as well as practitioners. This research attempts to put basic step and a frame work for cyber security body of knowledge and to allow practitioners and academicians to face the problem of lack of standardization. Furthermore, the paper attempt to bridge the gap between the different audience. The gap is so broad that the term of cyber security is not agreed upon even in spelling. The suggested body of knowledge may not be perfect yet it is a step forward.

MP3 is a standard that is used for encoding/decoding audio data. The standard can lower audio bit rate significantly without any loss. For this reason, it is key to understand how it does so, and secondly, find out if it is doable. Raw audio signals carry large data quantities and are neither suitable for transmission nor storage [2]. Therefore it is necessary to compress audio and at the same time maintain its quality as required by the International Organization for Standardization (ISO). MP3 was developed by the Motion Pictures Experts Group for audio and video compression. It is composed of three modes; the third referred to as Layer III. It is this layer that lowers raw-audio data bit rates from i.e. 1.4 Megabits per second to just 128 kilobits per second and can still reconstruct the signals to a level comparable to the original [3]. The objective of this paper is to review and provide a simple idea of what Layer III does in relations to audio compression and decompression.

Concrete is no longer made of aggregates, Portland cement and water only it is not always incorporate so it requires at least one of the additional ingredients such as admixtures, supplementary Cementitious material or fibers to increase the strength and durability. Rice husk ash is one of the pozzolanic materials that can be blended with Portland cement for the production of durable concrete. Supplementary Cementitious materials prove to be effective to meet most of the requirements of durable concrete. Rice husk ash is found to be greater to other supplementary materials like silica fume and fly ash. In the current study an attempt has been made to investigate the strength parameters of M20 concrete (compressive and split tensile). For control concrete, IS method of mix design is adopted. Partial replacement of cement has been made with different percentage of RHA namely, 5%, 10% and 15%. Large range of curing periods starting from 7, 14 and 28 days are considered in the present study.

There is an increasing interest towards synthetic closures as an alternative to cork stoppers for sealing wine bottles. In this preliminary study, a set of testing conditions using the TA-HDI Texture Analyzer were implemented to measure selected mechanical parameters for the characterization of wine closures (natural and technical corks, co-extruded and injected synthetic closures in terms of compression force, extraction force and resilience. The results showed the presence of significant differences among the closures for the parameters tested. Injected closures were characterized by the highest weight (range = 6.8–7.2 g), whereas the corks showed wide variability (SD = 0.23–0.57 = 4.4–15.3%). The force required to pull-out the closure from the bottle ranged between 176 and 421 N and the extreme values were found on natural (196 ± 20 N) and technical cork (329 ± 39 N). The force of compression was highest for corks (1006–1046 N), whereas lowest values were found for the synthetic closures (566–639 N). The Principal Component Analysis grouped the synthetic closures according to the technology process, i.e. injected and co-extruded, whereas the corks broadened aside with a little dispersion of technical cork compared to the natural cork.

This research works on high symbolic Bengali text and transforms it into corresponding less symbolic English complying with the transliteration method. The Huffman-based approaches serve to compress retaining the original quality of the data. On the other hand, faster encoding and decoding is the most sophisticated sphere in data compression. We propose an adjacent distance array, a novel data structure based on the Huffman principle for encoding and decoding the character of transliterated text. The encoding and decoding algorithms have been explained for the introduced modus operandi and juxtaposed with conventional Huffman-based algorithms. Our research is outdoing than any regular Huffman-based algorithms, concentrating on the speed of the encoding and decoding manner discovered after estimating all decisions.