Heat transfer behavior in a rotating aluminum foam heat sink with a circular impinging jet

This work experimentally studied heat transfer associated with an impinging jet onto a rotating heat sink. Air was used as the impinging coolant, and a square Al-foam heat sink was adopted. The variable parameters were the jet Reynolds number (Re), the relative nozzle-to-foam tip distance (C/d), the rotational Reynolds number (Re_r) and the relative side length of the square heat sink (L/d). The effects of Re, C/d, Re_r and L/d on the dimensionless temperature distributions and the average Nusselt number were considered. For a stationary system, the results reveal that the average Nusselt number (Nu₀) with Al-foam was two to three times that without Al-foam. Nu₀ increased with Re. A larger L/d responded to a larger Nu₀ based on the same jet flow rate. The effect of C/d on Nu₀ was negligible herein. For a rotating system, when Re and L/d were small and C/d was large, the average Nusselt number (Nu_Ω) increased considerably with Re_r. Additionally, for Nu_Ω/Nu₀ ? 1.1, the results suggest that rotation was substantial at Re_r/Re ? 1.13 when L/d = 4.615 with C/d = 0–5 and at Re_r/Re ? 1.07 when L/d = 3.0 with C/d = 0–5. For L/d = 2.222, rotation was substantial at Re_r/Re ? 1.44 when C/d = 0 and was always substantial when C/d ? 1.     

Process Characterisation of Pulsed Nd:YAG Laser Seam Welding

A wide range of pulsed laser welding parameters was identified. These include average peak power density (APPD), peak power, mean laser power, traverse speed, pulse repetition rate, duty cycle, pulse energy, spot size, and pulse duration. The type of laser beam temporal pulse shape studied was a rectangular power pulse. The effects of pulsed laser welding parameters on heat flow, weld dimension, and weldability are investigated. The study shows that weld quality is principally affected by APPD, mean power, and traverse speed, of which APPD is the most critical process parameter. A processing map containing the APPD effects is constructed as a guide for producing good welds.     

Purification and Characterization of Low Molecular Weight Kininogen from Pig Plasma

A cysteine proteinase inhibitor from pig plasma with a molecular weight (MW) of 55 kDa, purified to electrophoretical homogeneity, inhibited μ- and m -calpains, cathepsins B, L, and L-like, and papain, but did not inhibit trypsin, β-chymotrypsin, and cathepsin D. The purified inhibitor was stable at pH 3.0 to 10.5. The amounts for 50% inactivation (ID₅₀) of papain, cathepsins B, L, and L-like, μ- and m-calpains were 10.55, 12.91, 2.18, 2.18, 30.91, and 29.27 nM, while the inhibition constant (K_i) for cathepsins B, L, L-like, and X, and μ- and m-calpains were 1.1, 0.64, 63.33, 8.19, 26, and 23.57 nM, respectively. It could inhibit the proteolysis of mackerel myosin heavy chain caused by purified cathepsin L-like at 55 °C. Based on the MW, stability and specificity, it was identified as L-kininogen.     

Inhibition of Thermal Degradation of Mackerel Surimi by Pig Plasma Protein and L-kininogen

ABSTRACT: Use of purified L-kininogen to prevent actomyosin (AM) degradation by cathepsins, and pig plasma proteins to reduce mackerel modori were investigated. Myosin heavy chain (MHC) degradation in AM containing various cathepsins was significantly inhibited by purified L-kininogen. The texture of mackerel gel increased to 2-fold and 1.7-fold in breaking force (g) and deformation (cm) separately after adding 1% pig plasma protein. SDSPAGE showed that degradation of MHC in mackerel surimi was significantly reduced after 1% pig plasma protein addition at several temperatures. It suggested that the pig plasma protein containing L-kininogen could effectively reduce the modori phenomenon of mackerel surimi during processing.     

Modeling and measurement of active parameters and workpiece home position of a multi-axis machine tool

The complex structures of a multi-axis machine tool may produce inaccuracies at the tool tip caused by dimensional errors in the machine's link parameters. This paper addresses two important issues for precision machining: (1) which link parameters (denoted as active parameters) of a machine tool can affect the machining accuracy of a workpiece and (2) how to measure the active parameters by using a grinding wheel as a measuring probe. To achieve this, a modified Denavit–Hartenberg (D–H) notation is introduced to model a multi-axis machine tool. The NC data equations are then derived in terms of the machine's link parameters. It is found that the link parameters of a machine tool can be divided into two types: active and nonactive parameters. The prerequisite for obtaining an accurately machined workpiece is to have correct values of the active parameters and the workpiece home position. Based on the developed NC data equations of a multi-axis machine tool, this paper also addresses the technique of using a grinding wheel as a measuring probe to determine the active parameters and the workpiece home position. Experimental results are also given with illustrative examples.     

alpha-Methylene-gamma-butyrolactones: synthesis and vasorelaxing activity assay of coumarin, naphthalene, and quinoline derivatives

Certain alpha-methylene-gamma-butyrolactone derivatives of coumarin, naphthalene, and quinoline were synthesized and evaluated for vasorelaxing effects on isolated rat thoracic aorta. The 7-[(2,3,4,5-tetrahydro-2-methyl-4-methylene-5-oxo-2-furanyl)methoxy]-2H- 1- benzopyran-2-ones, which have an aliphatic methyl substituent at the lactone C2, were more active than their C2-phenyl counterparts against high-K+ (80 mM) medium, Ca2+ (1.9 mM)-induced vasoconstriction and the norepinephrine (NE, 3 microM)-induced phasic and tonic constrictions (2a vs. 2b; 2c vs. 2d; 2e vs. 2f; 2g vs. 2h). Although 3-chloro-7-[(2,3,4,5-tetrahydro-2-methyl-4-methylene-5-oxo-2- furanyl)methoxy]-4-methyl-2H-1-benzopyran-2-one (2g) demonstrated the most potent inhibitory activities on the NE-induced phasic and tonic constrictions at concentrations of as low as 10 micrograms/ml, it possesses both affinity for NE-receptor and intrinsic activity to trigger the vasoconstriction. However, 8-[(2,3,4,5-tetrahydro-2-methyl-4-methylene-5-oxo-2- furanyl)methoxy]quinoline (10a) and other quinoline derivatives (11a, 12a) are pure irreversible non-competitive blockers of NE-receptor with no intrinsic activity. The aromatic ring played an important role in the vasorelaxing effects of alpha-methylene-gamma-butyrolactones; naphthalene was inactive, quinolines exhibited only affinity to the alpha-receptor, and coumarins possessed both affinity and intrinsic activity.     

Wide bandwidth low noise pinFET receiver for high-bit-rate opticalpreamplifier applications

A wide bandwidth low noise pinFET receiver has been fabricated and characterised for optical preamplifier applications. The receiver uses a low capacitance planar pin diode as the photodetector. A bandwidth of 7.08 GHz was measured. The measured input noise current for the receiver front-end is lower than 12 pA/√(f). Using a 1.3 μm DFB laser as the transmitter, at a data rate of 4 Gbit/s, the measured receiver sensitivity is -25.5 dBm with a bit-error-rate of 1×10 ^-9. A set of two of such receivers has also been tested in a 1.3 μm polarisation-insensitive optical preamplifier system experiment. The measured receiver sensitivity, including an optical insertion loss of 1.5 dB, is -29.3 dBm     

A detailed R-L fed bridge converter model for power flow studies inindustrial AC/DC power systems

Because of lower voltage levels and smaller power ratings, the R/X ratio of commutation impedance in industrial AC/DC distribution systems is usually higher than that in HVDC transmission systems. Considerable discrepancies may therefore occur in industrial AC/DC power flow results, especially the reactive power consumption of converters, if the commutation resistances of the converters are neglected. To describe the effects of commutation impedance on converter operations and to precisely relate the fundamental line current and DC output current of the converter, a detailed model of the bridge converter with commutation impedance for use of Newton-Raphson power flow studies in industrial AC/DC power systems is derived in this paper. A coal mine power system and a DC electrified transit railway system with regenerative braking function, a part of Taipei Rapid Transit Systems under planning, have been analyzed to show the improved accuracy and good convergence characteristics of the developed Newton-Raphson power flow formulation with the proposed converter model