Discrete fractional watermark technique

Frontiers of Information Technology & Electronic Engineering - The fractional logistic map holds rich dynamics and is adopted to generate chaotic series. A watermark image is then encrypted and...     

PVC/Fe electrospun nanofibers for high frequency applications

In this article, we present a study on the microwave frequency properties of poly(vinyl chloride)/Fe composite nanofibers, with different concentrations of iron particles incorporated in poly(vinyl chloride) matrix. Using electrospinning, composite nanofibers were obtained with size ranging between 100 and 500 nm. The absorption properties of synthesized nanofibers were measured between two open-end rectangular waveguides in the 8–12 GHz frequency domain. The transmission loss measurements for poly(vinyl chloride)/Fe composite nanofibers demonstrated that this material can be used as protection material in X-band frequency domain. The applied magnetic field significantly modifies the measured scattering parameters in our samples case in a rather large domain of values for the field.     

Assessment of controlled short-circuiting application in filling passes with MIG/MAG double-wire process

In this work, a technical–economic assessment of the double-wire MIG/MAG welding process was carried out for flat-position welding of filler passes, employing controlled short-circuiting (CSC) operating mode in the trailing wire, as a way of improving control of the molten pool and reducing splashes. The assessment was based on a comparative study between the conventional double-wire MIG/MAG technique (using pulsed current in both wires) and a combination of pulsed current in the leading wire and CSC in the trailing wire. The following were kept constant: the values of average current for each wire, the volume of material deposited per unit length of weld, the type and size of the bevel and the wire, the composition of the shielding gas and the CTWD. The surface finish and geometry of the weld beads, deposition rate and deposition efficiency and the maximum welding speeds resulting from the use of each technique were assessed. The results show that the use of the CSC mode in the trailing arc increases the production capacity of the process slightly, leads to less splashing, improves the finish of the bead, produces smaller fusion zone and smaller HAZ and yet maintains a similar operational envelope (with respect to the range of useful welding speeds), which are positive factors. On the other hand, as a disadvantage, the use of CSC led to beads that are more convex and have less penetration.     

On Rationally DSP Implementation of the MP-MLQ/ACELP Dual Rate Speech Encoder for Multimedia Communications

The excellent performance in communications quality speech coding below 8 kbps achievable with the code-excited linear prediction (CELP) coders gives to this architecture a predominant role in medium-rate and low-rate speech coding, as evidenced by the adoption of several recent fixed-rate and variable-rate standards. Unfortunately, some of these CELP-based schemes are not completely described in the literature, and consequently they are difficult to understand and implement efficiently. This paper presents an original study of the G723.1 codec. The G723.1 encoder is dedicated to compress the voice signals with bandwidth up to 4 kHz efficiently and to deliver an encoded data stream with a very low binary rate and a good quality of transmitted speech (typical applications being encoding of the vocal signal for video conferences via GSTN and Voice over IP). We perform a detailed and gradually analysis, describing the MP-MLQ/ACELP speech coder from the point of view of a classical CELP structure. This approach allows us to identify (using theoretical considerations) the starting internal structure of each processing block from the encoder scheme. These results are used in breaking the main encoding algorithm loop. Finally, using the previously revealed starting internal structure, we derive the algorithm for the pitch predictor block, which is one of the most difficult parts of the ITU-T G723.1 encoder. The accompanying comments, explanations and diagrams allow efficient implementation and debugging of the corresponding software by regular DSP programmers.     

Skeletal calcium retention in hyperthyroidism and in vitro calcitonin inactivation

A radio isotopic technique is described to measure and monitor the cerebral blood volume during a controlled arterial hypotension induced by sodium nitroprusside in anesthetised patients (neurolepanalgesia) submited to surgery for a ruptured saccular aneurysm. The study was made in 10 cases from 90 mm Hg to 30 mm Hg mean blood pressure monitored from a transducer connected to an intra humeral microcatheter. The figures obtained show an increase of the cerebral blood volume from 90 mm Hg to 50 mm Hg in every patient and a linear correlation when the pressure is lowered under 50 mm Hg level; therefore under a mean arterial pressure of 50 mm Hg the autoregulation arterial mechanism is out of work.     

The rate of pressure rise of gaseous propylene-air explosions in spherical and cylindrical enclosures

The maximum rates of pressure rise of propylene-air explosions at various initial pressures and various fuel/oxygen ratios in three closed vessels (a spherical vessel with central ignition and two cylindrical vessels with central or with top ignition) are reported. It was found that in explosions of quiescent mixtures the maximum rates of pressure rise are linear functions on total initial pressure, at constant initial temperature and fuel/oxygen ratio. The slope and intercept of found correlations are greatly influenced by vessel's volume and shape and by the position of the ignition source--factors which determine the amount of heat losses from the burned gas in a closed vessel explosion. Similar data on propylene-air inert mixtures are discussed in comparison with those referring to propylene-air, revealing the influence of nature and amount of inert additive. The deflagration index KG of centrally ignited explosions was also calculated from maximum rates of pressure rise.     

The tribological behaviour of mineral oils additivated with polyethylene

The paper investigates the elastohydrodynamic lubrication of concentrated contacts in a rolling bearing operating at moderate speeds. Two base oils with different characteristics, additivated with low-density polyethylene were used as lubricants. Rheological and tribological tests were performed to study the influence of temperature, polymer concentration, and bearing speed. The influence of the addition of a polymer component on the film-forming properties and on wear under high pressure was examined in a four-ball test rig. Experimental data show that the polymer concentration added to the base oil plays an important role in obtaining greater film thicknesses and in preventing wear in elastohydrodynamic contacts.     

Molecular Mechanisms of Muscle Fatigue

Muscle fatigue (MF) declines the capacity of muscles to complete a task over time at a constant load. MF is usually short-lasting, reversible, and is experienced as a feeling of tiredness or lack of energy. The leading causes of short-lasting fatigue are related to overtraining, undertraining/deconditioning, or physical injury. Conversely, MF can be persistent and more serious when associated with pathological states or following chronic exposure to certain medication or toxic composites. In conjunction with chronic fatigue, the muscle feels floppy, and the force generated by muscles is always low, causing the individual to feel frail constantly. The leading cause underpinning the development of chronic fatigue is related to muscle wasting mediated by aging, immobilization, insulin resistance (through high-fat dietary intake or pharmacologically mediated Peroxisome Proliferator-Activated Receptor (PPAR) agonism), diseases associated with systemic inflammation (arthritis, sepsis, infections, trauma, cardiovascular and respiratory disorders (heart failure, chronic obstructive pulmonary disease (COPD))), chronic kidney failure, muscle dystrophies, muscle myopathies, multiple sclerosis, and, more recently, coronavirus disease 2019 (COVID-19). The primary outcome of displaying chronic muscle fatigue is a poor quality of life. This type of fatigue represents a significant daily challenge for those affected and for the national health authorities through the financial burden attached to patient support. Although the origin of chronic fatigue is multifactorial, the MF in illness conditions is intrinsically linked to the occurrence of muscle loss. The sequence of events leading to chronic fatigue can be schematically denoted as: trigger (genetic or pathological) -> molecular outcome within the muscle cell -> muscle wasting -> loss of muscle function -> occurrence of chronic muscle fatigue. The present review will only highlight and discuss current knowledge on the molecular mechanisms that contribute to the upregulation of muscle wasting, thereby helping us understand how we could prevent or treat this debilitating condition.     

Degradation by Electron Beam Irradiation of Some Composites Based on Natural Rubber Reinforced with Mineral and Organic Fillers

Composites based on natural rubber reinforced with mineral (precipitated silica and chalk) and organic (sawdust and hemp) fillers in amount of 50 phr were obtained by peroxide cross-linking in the presence of trimethylolpropane trimethacrylate and irradiated by electron beam in the dose range of 150 and 450 kGy with the purpose of degradation. The composites mechanical characteristics, gel fraction, cross-linking degree, water uptake and weight loss in water and toluene were evaluated by specific analysis. The changes in structure and morphology were also studied by Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy. Based on the results obtained in the structural analysis, possible mechanisms specific to degradation are proposed. The increasing of irradiation dose to 450 kGy produced larger agglomerated structures, cracks and micro voids on the surface, as a result of the degradation process. This is consistent with that the increasing of irradiation dose to 450 kGy leads to a decrease in crosslinking and gel fraction but also drastic changes in mechanical properties specific to the composites’ degradation processes. The irradiation of composites reinforced with organic fillers lead to the formation of specific degradation compounds of both natural rubber and cellulose (aldehydes, ketones, carboxylic acids, compounds with small macromolecules). In the case of the composites reinforced with mineral fillers the degradation can occur by the cleavage of hydrogen bonds formed between precipitated silica or chalk particles and polymeric matrix also.     

Aggregate features and A<Emphasis Type="SmallCaps">DA</Emphasis>B<Emphasis Type="SmallCaps">OOST</Emphasis> for music classification

We present an algorithm that predicts musical genre and artist from an audio waveform. Our method uses the ensemble learner ADABOOST to select from a set of audio features that have been extracted from segmented audio and then aggregated. Our classifier proved to be the most effective method for genre classification at the recent MIREX 2005 international contests in music information extraction, and the second-best method for recognizing artists. This paper describes our method in detail, from feature extraction to song classification, and presents an evaluation of our method on three genre databases and two artist-recognition databases. Furthermore, we present evidence collected from a variety of popular features and classifiers that the technique of classifying features aggregated over segments of audio is better than classifying either entire songs or individual short-timescale features. Editor: Gerhard Widmer