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In the paper, nanostructured, multimodal and conventional WC-12Co cermet coatings were sprayed by HVOF and the properties and structures of the coatings such as microhardness, microstructure, phase composition were compared. Finally sand solid and slurry erosion wear tests were carried out and their wear failure mechanisms were explored by XRD and SEM analysis. Research results show that microstructures of nanostructured and multimodal WC-12Co coatings prepared by HVOF are dense with little porosity, and their microhardness values are obviously higher than conventional WC-12Co coating. As well, it was found that nanostructured and multimodal WC-12Co coatings exhibited better sand solid and slurry erosion wear resistance in comparison with conventional coating and nanostructured WC-12Co coatings possessed the best sand solid erosion resistance properties at large impact angles and slurry erosion wear resistance. Testing results also show that although decarburization of WC occurred during spraying multimodal and nanostructured WC-12Co powders, the decarburization of WC for the nanostructured powder was more severe.

A series of experiments is carried out on the characteristics at the wedge bond interface. Bond lift-off characteristics are studied by using Scanning Electron Microscope with EDS-test. The characteristics of input impedance of PZT transducer are analyzed by the driving electric signal measured by Oscilloscope. Results show that the pattern of partially bonded material at the interface of ultrasonic wedge bonds exposed by peeling underdeveloped bonds simulates a torus with an unbonded central region. For the same machine variables, the input impedance and transforming power of the first wedge bond are greater than that of the second wedge bond. Some conclusions drawn by analyzing the input impedance and the power of PZT consist with the results gotten by testing microstructures at the interface.

In this paper, monotonic tensile and fatigue crack growth (FCG) studies were conducted on 7075-T6 Al substrates with and without bonded boron/epoxy patches. The Al substrates were machined to V-type side notch specimen. The presence of the pre-crack significantly decreased the plastic displacement and caused a slightly higher stiffness compared with the unnotched Al substrate. It was found that the repairs appeared to make the pre-cracked substrates slightly more plastic. The experimental results show that both static strength and fatigue life of the repaired aluminum substrates had been significantly increased for the bonded composite patches. The different patch-ply repairs were found to provide about a 5–14 times improvement in the fatigue life and a 2–4 times decrease in the stress intensity factor. The 4-ply-patch repaired specimen demonstrated its effectiveness in preventing static failure and increasing fatigue life of the cracked substrates. An analytical model, based on Rose's analytical solution and Paris' power law, was developed to predict FCG behavior of the repaired substrates. The analytical and experimental results are in good agreement.

Delta-6 fatty acid desaturases are rate-limiting desaturases involved in metabolic processes of fatty acids, and they are encoded by the FADS2 gene. In the current study, an F2 resource population of Gushi chickens crossed with Anak broilers was used to investigate the genetic effects of the chicken FADS2. Two adjacent single nucleotide polymorphisms (SNPs) (g.4290CG and g.4291CA) were identified in the transcriptional regulatory region of the FADS2 gene by means of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and created restriction site-PCR-RFLP. Associations between the two SNPs with chicken fatty acid contents and growth traits were determined using linkage disequilibrium, haplotype construction, and association analysis. The two SNPs and their haplotype combinations were significantly associated with linoleic acid (C18:2), α-linolenic acid (C18:3), arachidonic acid (C20:4), body weight (BW)2, BW4, BW6, shank girth (SG)4, and breast bone length 4 (P0.05). These results suggested that the SNPs of the FADS2 gene affected the content of essential fatty acid in muscle, and played a role in the early-stage growth rate of chickens.

This paper presents a new model of parallel manipulator for manufacturing, whose mechanism comes from the general Stewart platform which has the advantages of high rigidity and high load capacity. A scheme of the link mechanism is also proposed to make the link structure very simple. The mechanism parameters are optimized by workspace analysis of the parallel mechanism. With the view of kinematics equivalence between parallel mechanism and serial mechanism, by way of hypothesis serial mechanism and branch hypothesis serial mechanism, an efficient kinematics algorithm has been developed. The problem, derived motion produced by the link structure, has also been solved conveniently.

Coilia ectenes (Jordan and Seale 1905) is an important anadromous species that is an important resource at risk of extinction because of over-fishing, pollution, and coastal construction. To evaluate the genetic diversity of C. ectenes for use in breeding programs, elite microsatellite-enriched libraries were constructed and novel microsatellite markers were developed, and applied to genetically detect wild populations. Out of 92 randomly selected and sequenced clones, 89 contained a CA or GA repeat motif. Twenty-two pairs of primers were designed to investigate the polymorphism and genetic structure of a wild population collected from the Yellow River estuary, China. It was found that 2 loci were monomorphic and 20 loci were polymorphic. The number of alleles per polymorphic loci ranged from 3 to 13, with an average of 7.9. The expected heterozygosity per locus ranged from 0.05 to 0.89, with an average of 0.68. The isolated polymorphic markers are expected to be of use in future genetic breeding programs for C. ectenes, and in the assessment of genetic variation within this species.

Bipolar DC corona is known to be a strong function of conductor voltage but little is known about the influence of load current on bipolar corona. To evaluate the influence of load current, a bipolar cylindrical corona cage was constructed and operated with simulated DC load current flowing in the conductors. Measurements of load current, corona current, ion current density, and conductor temperature show that corona conductance is a function of load current. The load current depends on temperature rather than magnetic field. >

This paper presents an investigation on inserting damping oil-films into machine tools rolling slideways. It indicates that the vibration-proof ability of the system can be improved significantly by this means as well as its proper moving sensitivity and low-speed moving stability are preserved. The experimental formula of the damping coefficient of rectangular oil-films with a parallel gap is presented through tests. The rolling slideways system with damping oil-films is modelled in accordance with the special characteristic of the structure and the corresponding identification method of the damping coefficient is presented. Furthermore, computer simulative experiments are carried out. On the basis of the analysis of the results the objective for optimization of oil-film damping parameters is given.

A two-dimensional particle simulation model was developed to investigate wind effects on charge density measurements under HVDC lines, using a radioactive probe. The particle simulation technique was successful in macroscopically describing the motion of charged particles under the influence of wind, electric field, and diffusion. The simulation results were in good agreement with wind tunnel experiments. The simulation revealed that at higher wind speeds, the charged particles in the ionization region were convected away faster than at lower wind speeds. This reduced the recombination rate at the probe and thereby resulted in a more negative floating potential. At constant wind speed, the floating potential was less negative when the probe emitting surface was in the wake because wind velocity in the wake was much smaller (assumed zero in the simulation.). >

This paper presents a study of oil-film damping technique for rolling slideways system both on theory and experiment. The structure, principle and effect of the damping oil-film are illustrated. Problems for the design of oil-film including inertial effect, amplitude effect, machining error and the choose of the oil-film gap-width are analyzed. Keywords: Rolling slideways; Damping; Oil-film.

Summary form only given. Experiments have shown that the floating potential of a polonium 210 radioactive potential probe in air is a function of wind speed and direction. Polonium 210 decays by emitting 5.3-MeV alpha particles which have a range in STP air of about 3.8 cm. Each alpha particle creates about 105 electron-ion pairs in its wake. Within a microsecond of their creation, the free electrons either recombine with positive ions or attach to molecules to create negative ions. The floating potential of the probe becomes more negative (s-1.0 V) as the wind speed increases within tie range 0-5/ms. The floating potential is also observed to be more negative when alpha particles are emitted upstream rather than downstream. This phenomenon is being studied with a two-dimensional particle-in-cell simulation. Finite difference methods are used to solve Poissons equation and to move simulation particles under the influence of mobility, convection, diffusion, and recombination. A variable cell size has been used to provide improved resolution near the probe. Simulation particles represent positive and negative ions created by the emitted alpha particles. The number of simulation particles created per time step is determined by the activity (s5 mCi) of the radioactive probe and by the length of the time step. Space charge separation and an electric field result from incomplete neutralization of negative charge on the radioactive probe