Conformance Mark Introduced by CAS

On July 15th 2004, China Association For Stan-dardization (CAS) held official business con-ference the second time of this year in Beijing, which is its 5th Council Meeting. The conference was mod-erated by Li Rui, President of CAS's Board of Direc-tors. Vice-presidents Li- Zhonghai, JiaoYunqi and Jing Xiaodong, Secretary-General Ma Lincong and Zhang Wei, and other cadres totally more than 20 delegates attended the conference. In the meeting, both Secretary-General Ma Lincong a…     

High Strength Conductor by Directional Solidification

The directional solidification of Cu-0.8 wt pct Cr alloy was investigated for high-strength conductors. An in-situ composite material in which the matrix is in cellular morphology and the well-distributed eutectics around the cells is formed in the directional solidification process. In such microstructure, the cellular matrix is as conductor and the coated-around eutectics as reinforcement. The formation mechanism of this microstructure is discussed from the interfacial instability. As a result, the tensile strength of the material along the solidification direction is two times more than that of the conventionally cast one, while the electrical conductivity is reduced a little by comparison with the pure Cu.     

Preparation of γ-alumina thin membrane by sol-gel processing and its characterization by gas permeation

-alumina porous membranes without pinholes or cracks were prepared by the sol-gel process. The boehmite sol obtained from hydrolysation of aluminium isopropoxide was applied to the inner surface of a porous supporting tube by a dipping procedure. The effects of sol concentration and the repetition number of dipping-drying-firing procedure on the membrane performance were investigated by scanning electron microscopy, X-ray diffraction and the Brunauer-Emmett-Teller method in connection with the micro-structure of the membrane. Gas permeation measurements were also conducted. The gas permeation through the thin membranes is well explained by Knudsen's flow, indicating the pores are controlled finely and homogeneously.     

High-quality graphene films produced by freezestretching alignment

Monolayer graphene has the highest tensile strength,Young’s modulus, and electrical conductivity of known materials, and it is expected to be used in aerospace,automobiles, flexible electronics, etc. [1]. However, the extraordinary properties of graphene are on the molecular level and have not been realized when assembled into macroscopic materials.     

Beryllium Surface Modified by B Ion Implantation

Beryllium is implanted with 100 keV,2×10~(17) B/cm~2 and post-implanted sample isannealed at 650℃ for 1 h.Hardness measurementindicates that the hardness increases withimplantation and can further be modified bypost-implantation heat treatment.Profile measurement shows that implantationcauses contamination on the surface of beryllium.During annealing boron diffuses out of berylliumand carbon on surface diffuses into beryllium.Beryllium surface is modified by compositionchange and carbide formation.     

Surface Yielding of Metals by X-ray Diffraction

Surface yielding of metallic material was measured with strain gage and X-ray diffraction methods.The results show that.when the residual stress in the transverse direction is involved,the surface yieldstrength should be evaluated with biaxial Mises criterion.For a medium carbon high strength steel,the yield strength of the bulk material is 581 MPa and the surface yield strengths for 0.05% and0.1%plastic strain are about 436 MPa and 463 MPa respectively.The 0.05% yield strength willapproximately increase to 788 MPa after shot peening.In the early stage of plastic deformation,strain hardening in the surface layer is quite different from that of the bulk sample.     

Effect of strain on “hardening by annealing and softening by deformation” phenomena in ultra-fine grained aluminum

Ultra-fine grained (UFG) metals fabricated by severe plastic deformation (SPD) sometimes exhibit peculiar mechanical properties. For example, the “hardening by annealing and softening by deformation” was reported in UFG aluminum, which was totally opposite to the behaviors of conventionally coarse-grained materials. In this study, the effect of SPD strain on the peculiar phenomena was investigated. The UFG aluminum was fabricated by various cycles of the accumulative roll-bonding (ARB) process with lubrication at ambient temperature. The specimen ARB-processed by ten cycles certainly showed the peculiar phenomena. On the other hand, the 6-cycle specimen did not show the phenomena but was softened by annealing and hardened by deformation normally. From the results of microstructural characterization, it was suggested that the difference in the change of the mechanical property during annealing and deformation between 6-cycle and 10-cycle specimens was caused by the difference in the grain size and/or the texture components, which depended on the SPD strain.     

Reconstruction of Complex Materials by Integral Geometric Measures

The goal of much research in computational materials science is to quantify necessary morphological information and then to develop stochastic models which both accurately reflect the material morphology and allow one to estimate macroscopic physical properties.A novel method of characterizing the morphology of disordered systems is presented based on the evolution of a family of integral geometric measures during erosion and dilation operations .The method is used to determine the accuracy of model reconstructions of random systems.It is shown that the use of erosion/dilation operations on the original image leads to a more accurate discrimination of morphology than previous methods.     

CVD SiC Fiber Electrochemically Treated by AC Current

The tensile strength of CVD SiC fiber was remarkably improved by electrochemical surface treatment. SEM analyses reveal that AC current treatment could form a more compact and complete SiO2 layer than DC current on the surface of the SiC fiber, which was beneficial to the improvement of tensile strength. It was also verified that AC current was more effective for producing high performance SiC fiber with SiO2 surface layer than DC current. The frequency is a sensitive parameter for the process; but the signals of input current had relatively small effect on the tensile strength of SiC fiber. A further discussion for this phenomenon was completed. The proposed operational parameters are 0.3A, 5kHz of sine wave and 91m/h of the receiving rate respectively.     

Technique of Aluminum Alloy Composite by Inversion Casting

The influence of the temperature of liquid aluminum alloy,the dipping time in liquid alloy and the thickness of base strips on the solidified layer was studied during the process of producing aluminum alloy composite strips used in automobile radizator with inversion casting.It is concluded that there is welding as well as diffusion of alloying elements between the base strip and the coating.Experiments proved that the interface has a good bonding.     

Ceramics Surface Modification by Excimer Laser Metal Coating

Thin metallic layers (~ 2 μm) of Ni were deposited on polycrystalline Al2O3. ZrO2 and (Ce-TZP)+Al2O3 ceramic substrates. and further irradiated with pulsed excimer (Xeno chloride) laser pulses. The laser energy density was varied from 0.21 to 0.81 J / cm2 to optimize bending strength. For ZrO2 ceramic, it was found that the strength increases from 530 to 753 MPa at 0.51 J / cm2 irradiation. For Al2O3 and (Ce-TZP)+ Al2O3 the fracture strength also increases in varying degree. The causes of strength increment were discussed.     

Matrix Crack Detection by an Embedded Polarimetric Sensor

Polarimetric optical fibre sensors have been embedded within the 0° ply and close to the 0/90 interface of transparent cross-ply GFRP coupons. The laminate ply cracks may initiate and propagate across the coupon when the coupons were subjected to an increasing quasi-static load in a servo-hydraulic testing machine. Crack accumulation have been monitored using a long gauge-length extensometer. The response of the strain signal, the optical signal and the load signal to cracks at different positions in the coupon in relation to the extensometer and optical sensor positions have been acquired and compared by means of video images of the crack growth. The relationship between crack growth and sensor response was demonstrated. The displacement induced by a new transverse crack has been predicted and compared with experimental data.     

Fabrication of Iron-base Alloy by Spark Plasma Sintering

Fe-2Cu-2Ni-lMo-0.8C (wt pct) elemental mixed powders were rapidly sintered within 6 min by spark plasma sintering, and the effects of sintering parameters on the densification degree and performance of the assintered materials were investigated. Results showed that when a proper combination of pulse electric current and constant electric current was employed for sintering, the density and bend strength of the as-sintered material reached the maxima, being 7.61×103 kg/m3 and 1540 MPa, respectively. Its corresponding fracture morphology was characterized as the mix of ductile, intergranular and cleavage fractures.     

Five China multimedia related standards certified by ITU

Followed China's breakthrough in IP and multimedia related international standards participation highlighted by its dominant four international standards in ITU/SG15 being accepted by international community, other five China dominant international standards were certified in ITU meeting in Nov, 2006. They are: Security Protocol Negotiation (H.460.22) co-developed by China Telecom Research Institute and ZTE Corporation, and Video Gamma Compensation Process and Value Assignment in Multimedia System (H.272), Supplementary 1: Distinguishing Calling Type Enhancement (H.248.2), Connection Capability Control Package (H.248.46) and Statistical Conditions Control Package (H.248.47) developed by Huawei Corporation.     

Nano-composite Particles Synthesized by a Hydrogen Arc Plasma

Nano-composite particles can be synthesized by a hydrogen arc plasma method, which possesses the advantages of high productivity, controllable size distribution and low electric energy consumption comparing with conventional gas condensation method. With this method, not only the nanoparticles of metals and alloys, but also the nano-composite particles with shell structure can be synthesized. The microstructures, compositions and the formation mechanism of the nano composite particles were studied     

Entanglement-induced population trapping by Schrödinger's cat

Abstract

We propose an experiment that is a variation of the Schrödinger's cat ′paradox' wherein the entanglement between a microscopic system and a macroscopic system is of primary interest. The experiment involves tunable entanglement and serves as a model for controllable decoherence in the context of cavity quantum electrodynamics where atoms interact dispersively with a cavity field initially in a coherent state. The interaction produces an entanglement between the atom and the field, and the degree of entanglement can be probed by subjecting the atom to resonant classical radiation after it leaves the cavity. The amplitude of the resulting Rabi oscillations reflects the degree of the entanglement, there being no Rabi oscillations when the entanglement is maximum. We show that the cavity damping does not affect the experiment.     

The Diagnosis of Reciprocating Machinery by Bayesian Networks

A Bayesian Network is a reasoning tool based on probability theory and has many advantages that other reasoning tools do not have,This paper discusses the basic theory of Bayesian networks and studies the problems in constructing Bayesian networks.The paper also consturcts a Bayesian diagnosis network of a reciprocating compressor.The example helps us to draw a conclusion that Bayesian diagnosis networks can diagnose reciprocating machinery effectively.