Relationship of testicular weight to age and scrotal circumference of Holstein bulls.

Testicular weights were recorded for 250 Holstein bulls ranging in age from 19 to 189 mo. The multiple regression equation that best described the relationship between paired-testes weight and age of bull was Y = -368.8 + 952.2 LOG X - 180.3 (log X)2, where Y is paired-testes weight in g and X is bull age in mo. Correlations between these two variables were .86 for 24 bulls less than or equal to 60 mo of age and .60 for 23 greater than 60 mo of age. A linear regression equation for 47 bulls was Y = -645.5 + 34.0 X, where Y is paired-testes weight in g and X is scrotal circumference in cm measured within 1 mo of slaughter. The correlation coefficient was .79. Differences in testicular weights of bulls of similar ages were large. These should be taken into account by measuring scrotal circumference and selecting young bulls with larger testes and superior spermatozoal producing capabilities.     

iMAC: improved Medium Access Control for multi‐channel multi‐hop wireless networks

Trends in wireless networks are increasingly pointing towards a future with multi‐hop networks deployed in multi‐channel environments. In this paper, we present the design for iMAC—a protocol targeted at Medium Access Control in such environments. iMAC uses control packets on a common control channel to facilitate a three‐way handshake between the sender and the receiver for every packet transmission. This handshake enables the sender and the receiver to come to a consensus on a channel to use for data transmission and also signals to neighboring nodes about the contention on that channel. iMAC then uses a mechanism similar to 802.11 for data communication. Our evaluation of iMAC shows that it provides significant gains in throughput in comparison with uninformed channel selection, especially when contention for channel bandwidth is neither too low nor too high; intelligent selection of channels by iMAC is necessary to harness available bandwidth resources in the presence of medium levels of contention. Copyright © 2011 John Wiley & Sons, Ltd.     

Scratch Cell Test: A Simple,Cost Effective Screening Tool to Evaluate Self-Healing in Anti-Corrosion Coatings

A quick and simple scratch cell set up to evaluate the self-healing of an hybrid sol-gel (ormosil) coating was fabricated. This methacrylate-based anti-corrosion coating was applied on the aerospace aluminium alloy AA2024-T3, and cured at room temperature. This technique of evaluation requires minimum instrumentation. The inhibitors cerium nitrate, benzotriazole and 8-hydroxy quinoline (8-HQ) were used in the study. The self-healing ability of the inhibitors decreased in the following order: 8-HQ, BTZ and Ce. 8-HQ showed the highest self-healing ability and was comparable to the commercial hexavalent chromium conversion coating—Alodine. Spectroscopic analysis of the electrolyte and EDX of the coatings indicated the movement of the inhibitor from the coating to the site of damage, thereby effecting self-healing. It was observed that an increased inhibitor concentration in the coatings did not accelerate the healing process. Inhibitor release was slower in the coatings doped with inhibitor-loaded nano-containers, when compared to inhibitor-spiked coatings. This property of controlled release is desirable in self-healing coatings. Electro impedance studies further confirmed self-healing efficiency of the coatings. The scratch cell study reported here is the first of its kind with the ormosil under study on AA2024-T3 aluminium alloy. The results are encouraging and warranty a quick and simple qualitative screening of the self-healing potential of the inhibitors with minimum instrumentation.     

Thermo-luminescence Based Computed Radiography (TLCR)

Computed radiography (CR) is an X-ray imaging technique that was developed as early as the 1980s but its acceptance in the real-world NDE has been more recent (in the last decade). Although there are many players in the market, every system is based on more or less similar technology. The technology involves storing the X-ray information, during X-ray exposure, in materials known as storage phosphors. The information is stored in a latent form and then later (at a desired time), this information is released to create an image using an external stimulation mechanism such as light. The work described in this paper assesses the feasibility of an alternate stimulation mechanism, namely heat, to release the trapped energy from the phosphors. This essentially enables one to move away from a point-by-point/ line-by-line scanning technique to an area read-out system. The paper further discusses a simple lens-camera read-out system to generate the X-ray image. The paper also evaluates the performance of such a system comparing it to existing CR systems and explores different mechanisms to improve its limitations.     

Impact of Die Geometry on Microhardness and Grain Size of Cold-Drawn Steel Wire

Two different heats of heading quality 302 stainless steel wire were drawn through three different conical die geometries. The microstructural response of the material was investigated via measurement of microhardness and grain size. The measurements across the transverse and longitudinal axes of the wires were then compared with strain measurements predicted through finite element modeling. Accuracy of the different measurements are compared, and an optimum “watch-dog” parameter for the verification of the modeling results is proposed.