The influence of the drawing parameters and temperature rise on the prediction of chevron crack formation in wire drawing

The objective of the present work is to predict the formation of chevron crack in copper wire drawing process. The first part of this paper is to determine the chevron crack formation initiated by a central burst inside the wire material using experimental tests. These results are compared with results from a series of numerical simulations using the Cockcroft?CLatham fracture criterion. The second part of this work concerns the determination of a curve that divides the chevron and safe zones for a better wire drawing process. The conditions of central burst defects formation along the wire axis depend on drawing parameters and friction coefficient between the die and the wire. The friction coefficient is defined as a linear function of temperature rise which is measured close to the wire-die interface. The obtained results show that the friction coefficient depending on temperature rise during wire drawing has an impact on the damage of copper wire.     

Effects of Electrical Stimulation on Histochemical Muscle Fiber Staining, Quality, and Composition of Camel and Cattle Longissimus thoracis Muscles

ABSTRACT:  The effects of electrical stimulation on muscle fiber type, meat quality, and composition of Longissimus thoracis muscles from one-humped camels and Dofari Omani cattle of a comparable age range were investigated. A low-voltage electrical stimulation with 90 V, 14 Hz (pulse of 7.5-millisecond duration every 70 milliseconds) 20 min postmortem was applied. Samples from the left muscle were collected from 20 (2 to 3 y) camels and 24 cattle (1 to 3 y). For chemical composition, muscle samples were dried in a freeze dryer, and then ground to determine moisture, protein, fat, and ash. Macro- and micro-minerals were determined using an Inductively Coupled Plasma Emission Spectrometer. Quality characteristics of the meat were evaluated using shear force value, pH, sarcomere, myofibrillar fragmentation index, expressed juice, cooking loss percent, and CIE L *, a *, b * color values. Electrical stimulation resulted in a significantly ( P < 0.05) more rapid pH fall in the muscle during the first 24 h after slaughter in both species. Muscles from electrically stimulated carcasses had significantly ( P < 0.05) lower ultimate pH, longer sarcomere, and lower shear force values than those from nonstimulated carcasses. Lightness ( L *), myofibrillar fragmentation, and expressed juice were significantly ( P < 0.05) higher for stimulated than for nonstimulated muscles. Muscles of camels had significantly ( P < 0.05) higher expressed juice, cooking loss percent, redness color ( a *), and lower fat, Mg, K, and P than those from cattle. Electrical stimulation improved quality characteristics of meat from both species. This indicates that meat quality of local camel and cattle can be improved by electrical stimulation and consequently improves their acceptability to consumers and better marketability.     

Chlor-alkali electrolysis with oxygen depolarized cathodes: history,present status and future prospects

The historical development, current status and future prospects of chlor-alkali electrolysis with oxygen depolarized cathodes (ODCs) are summarized. Over the last decades, membrane chlor-alkali technology has been optimized to such an extent that no substantial reduction of the energy demand can be expected from further process modifications. However, replacement of the hydrogen evolving cathodes in the classical membrane cells by ODCs allows for reduction of the cell voltage and correspondingly the energy consumption of up to 30%. This replacement requires the development of appropriate cathode materials and novel electrolysis cell designs. Due to their superior long-term stability, ODCs based on silver catalysts are very promising for oxygen reduction in concentrated NaOH solutions. Finite-gap falling film cells appear to be the technically most mature design among the several ODC electrolysis cells that have been investigated.

An evaluation of the growth, carcass and meat quality characteristics of Omani goat breeds

Body weight, growth, carcass and meat quality characteristics were evaluated in three breeds of goats (Batina, Dhofari and Jabal Akdhar) in Oman. Fourteen intact male goats from each breed were used. Jabal Akdhar goats had significantly heavier slaughter, empty body, and carcass weights and higher growth rates than Dhofari and Batina goats. Jabal Akdhar goats had significantly heavier internal organs than the other two breeds. Dressing-out percent (based on empty body weight) of goats ranged between 53 and 57%, with the Dhofari goats having the highest value. Longissimus muscle dimensions varied between the three breeds, with Jabal Akdhar having a significantly larger area than Batina with Dhofari in between. Dhofari goats produced significantly shorter and wider carcasses than Batina and Jabal Akhdar goats. Carcass cuts were significantly heavier in Jabal Akdhar than the other two breeds. Four muscles (Mm. longissimus dorsi, biceps femoris, semitendinosus, and semimembranosus) from both sides of each carcass were subjected to two different ageing periods (1 day vs. 6 day) and evaluated for ultimate pH, expressed juice, percent cooking loss, colour (L*, a* and b*), and Warner-Bratzler shear force. Breed had a significant influence on pH and percent cooking loss but not on expressed juice, shear force value and colour (CIE L*,a*, b* values). Muscles from the Batina goats had significantly higher ultimate pH values and lower percent cooking loss than Dhofari and Jabal Akdhar goats. Ageing from 1 to 6 days increased tenderness significantly (27%), but decreased cooking loss by 5%.     

Ultrasonic scanning measurements of the longissimus thoracis et lumborum muscle to predict carcass muscle content in sheep

Nineteen Omani sheep (average 26 kg body weight) were scanned over the 6th rib, 12th rib and the second-last lumbar vertebra, to determine the maximum depth (B), circumference, area of the cross-section and volume of the longissimus thoracis et lumborum (LD) muscle. The volume of the muscle was estimated by multiplying the average area of its cross-section obtained at the three sites by its length. After slaughter, the LD muscle was dissected out, frozen, and its maximum depth, circumference, length, weight and volume were determined. Correlation and regression analyses were carried out to evaluate relationships between scanning and real measurements and between scanning measurements and carcass total muscle content. Generally there were positive correlations (r = 0.43-0.66) between the LD scanning measurements made at the 12th rib and the corresponding measurements made on the dissected muscle. The volume of the LD muscle estimated from scanning was positively correlated (r = 0.59) with its real volume which was correlated with its weight (r = 0.51) and consequently with the total carcass muscle content (r = 0.69). Ultrasonic scanning can be used to predict the circumference and volume of the LD muscle. These may be used for prediction of total carcass muscle content in sheep in addition to traditional measurements of the muscle (the maximum depth B) and area.     

Chemical composition,quality and histochemical characteristics of individual dromedary camel (Camelus dromedarius) muscles

This study characterized the chemical composition, quality and histological traits of six muscles from 10 dromedary carcasses. There were significant differences in moisture, fat, protein, mineral, saturated and unsaturated fatty acid contents between muscles. The longissimus thoracis (LT) had the highest cooking loss (33.5%) and triceps brachii (TB) the lowest (29.2%). The shear force value of semitendinosus (ST), semimembranosus (SM) and biceps femoris (BF) were significantly higher than infraspinatus (IS), TB and LT. The LT had significantly higher values for L*, a*, b* than ST. The SM had the lowest MFI (65.3), while IS had the highest value (75.8). The ST significantly had the highest and lowest proportions of Type I and Type IIA muscle fibers, respectively than other muscles. This study indicated that composition, quality, and histochemical parameters varied among camel muscles and the knowledge of this variation allows for better marketing and processing of camel meat.     

90° SOI optical hybrid for Radio-over-fibre links

Radio-over- fibre (RoF) technology is receiving large attention due to its ability to provide simple antenna front ends, increased capacity and increased wireless access coverage. Coherently detected RoF systems would enable the information to be carried in both the amplitude and phase or in different states of the polarisation of the optical field. Additionally, the selectivity of coherent receiver is very well suited for access networks. We present a 90° optical hybrid built on a silicon-on-insulator planar light-wave circuit, which can be used as the optical front end of the digital coherent receiver in a digitised RoF link and will lead to reduced receiver footprint and cost. The optical hybrid circuit includes 2?×?2 and 4?×?4 multimode interference (MMI) splitters, in a polarisation diversity configuration. The simulation results at vacuum wavelength 1,550 nm show polarisation independence and phase errors between the ports of less than 0.03°. The properties of the prototyped 4?×?4 MMI were measured over a wide range of wavelengths. The 2?×?2 and 4?×?4 MMI showed nearly equal splitting ratios. Measurements of the relative phase relationship between the ports for Transverse Electric mode polarisation are shown to match the simulation results.     

Effect of Doping of Zn and Ca into ErBa2Cu3O7?δ Superconductor Prepared via Co-precipitation Method

Zn- and Ca-doped ErBa₂Cu₃O_7−δ were successfully prepared via coprecipitation method using metal acetates as the starting salts. The precipitated samples were calcined for 20 h at 900 °C and sintered at 920 °C for 24 h. All heat treatments were carried out under oxygen environment. Results show that there is a selectivity of the doping site depending on the ionic radius of the dopant. Furthermore, increase in the critical temperature, T _c , was observed in 0.05 mole of calcium and zinc doped samples. The difference in ionic radius of the dopant led to the increase in porosity as the ionic radius decreases. On the other hand, structural distortion increased as the difference of ionic radius became larger.     

Corrosion inhibition of steel in crude oil storage tanks

The corrosion behavior of steel in water from certain oil fields with various organic inhibitors was studied by applying potentiodynamic technique at pH 5.9. The inhibitors which were used include 2‐methylbenzimidazole (I), 2‐mercaptobenzimidazole (II), 2‐mercapto‐5‐methylbenzimidazole (III), and 2‐mercaptothiazole (IV). The inhibiting efficiency of the different additives was evaluated from their anodic and cathodic polarization curves at different temperatures. A comparative study of curve fitting procedures using the kinetic thermodynamic model and those utilizing well‐known adsorption isotherms was undertaken. Three types of isotherms were used, Langmuir, Frumkin and Flory‐Huggins isotherm. The results show that the kinetic‐thermodynamic model and Flory‐Huggins isotherms are more suitable to fit the data for the four inhibitors, at all applied temperatures. From the values of binding constants, K, the order of inhibitor efficiency is: III > IV > II > I and thus 2‐mercapto‐5‐methylbenzimidazole was the most effective inhibitor. The thermodynamic parameters obtained for all the compounds used showed low values of H_ads, which indicates that the action of these inhibitors is physically adsorptive in nature.