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941.
在薄板坯连铸连轧流程上,经过对Ti微合金化技术研究,有效解决了Ti微合金化强度性能波动大的问题,开发出屈服强度450~700MPa高强钢。对试制钢组织性能和工业应用分析研究,表明该产品通板性能良好,通板强度差30MPa左右;成形性能良好,d=0时冷弯测试全部合格;同时还具有良好焊接性能,焊接后,强度波动较小,均在母材部位断开;试制钢显微组织为珠光体和铁素体,晶粒均匀细小,平均尺寸为4~8/μm;实物质量满足集装箱和汽车制造行业要求,具有广阔市场前景。 相似文献
942.
Most algorithms on receiver autonomous integrity monitoring (RAIM) are under the assumption of a single-satellite fault, because there is an extremely small probability that significant simultaneous multiple-satellite faults may occur. However, after the implementation of the Galileo system in a few years, there will be more satellites in view for the user to utilise together with GPS satellites, and a combination of them will bring better performance for RAIM. On the other hand, with the help of wide area augmentation system and the use of dual-frequency operation, pseudo-range errors will be reduced greatly. Thus, tighter alert limits are required for RAIM, and formerly `small' errors should not be neglected. All of those factors make it necessary to consider simultaneous multiple-satellite faults. A detailed theoretical analysis of RAIM under the condition of two-satellite faults for both vertical and horizontal directions is presented. The characteristic/max slopes for every pair of satellites are then deduced in order to calculate the tighter vertical/horizontal protection level for RAIM 相似文献
943.
Wang Xuegang Yan Fengjie Yan Qian Li Xingeng 《Frontiers of Materials Science in China》2007,1(2):225-227
An iron-based amorphous foil (FeNiCrSiB) was used as an interlayer for the amorphous diffusion bonding of low carbon steel
pipes under argon flux. The microstructure and mechanical properties of the joint were analyzed using an electron probe micro-analyzer
(EPMA), tensile test, bending test and impact test. The results show that the joint microstructure resembles that of the base
metal and no precipitates form at the joint. Melting point depressants (B, Si) diffuse far away from the joint and the base
metal element is homogenous across the joint. The joint impact toughness is greater than the base metal toughness and the
mechanical properties of the joint are similar around the pipe. 相似文献
944.
A digital signal processor-based control system for the permanent magnet-assisted reluctance synchronous machine, with the emphasis on dynamic performance, is proposed. A classical design approach is used to design the current and speed controllers for the machine. The stator current of the machine is controlled in such a way that the current angle in the dq synchronous reference frame is constant. The load-torque is estimated using a state space observer and compensation current based on the estimated load is used to improve the dynamic performance of the drive. The control system design is machine specific as it relies on data from finite-element analysis. Simulated and measured results on a 110-kW power level show that the resulting control system is stable and robust with good dynamic performance 相似文献
945.
Experimental results on error-free bidirectional transmission of 8times10 Gigabit Ethernet channels over 210 km of standard single mode fibre are presented here. Inexpensive XENPAKs transceivers, conventional unidirectional 1530-1560 nm (C-band) erbium-doped fibre amplifiers and fibre Bragg grating dispersion compensating modules have been used. The results are very promising, especially for operators of national research and educational networks 相似文献
946.
Jonathan P. Belnoue Giang D. Nguyen Alexander M. Korsunsky 《International Journal of Fracture》2007,144(1):53-60
This paper presents a new 1-D non-local damage-plasticity deformation model for ductile materials. It uses the thermodynamic
framework described in Houlsby and Puzrin (2000) and holds, nevertheless, some similarities with Lemaitre’s (1971) approach.
A 1D finite element (FE) model of a bar fixed at one end and loaded in tension at the other end is introduced. This simple
model demonstrates how the approach can be implemented within the finite element framework, and that it is capable of capturing
both the pre-peak hardening and post-peak softening (generally responsible for models instability) due to damage-induced stiffness
and strength reduction characteristic of ductile materials. It is also shown that the approach has further advantages of achieving
some degree of mesh independence, and of being able to capture deformation size effects. Finally, it is illustrated how the
model permits the calculation of essential work of rupture (EWR), i.e. the specific energy per unit cross-sectional area that
is needed to cause tensile failure of a specimen. 相似文献
947.
The polycrystalline samples of Dy
x
Bi1−x
FeO3 (x = 1, 0.8, 0.6, 0.4 and 0.2) were synthesized by standard solid state reaction technique. The samples synthesized were characterized
by X-ray diffraction (XRD) technique. Further the samples were characterized by infrared (IR) spectroscopic technique. The
dielectric measurements were carried out as a function of frequency in the range 100 Hz to 1 MHz at room temperature. Also
the dielectric measurements were carried out as a function of temperature at certain fixed frequencies. The ac and dc resistivity
measurements were carried out using two probe method. Also temperature dependence of ac and dc resistivity was noted. These
measurements suggest polaron conduction in the samples. Finally, the data from XRD, IR, dielectric measurements were correlated. 相似文献
948.
The equilibrium shape and dihedral angles at the solid–liquid–vapor tri-junctions of two-phase alloy small particles containing
a cusp-oriented interface were modeled as a function of phase fraction, surface energy and the interfacial energy. The calculation
was applied to different combinations of surface and/or interfacial energies to demonstrate the various possible particle
shapes and dihedral angles that result for two-phase particles. The dihedral angles at the tri-junction vary with the phase
fraction, due to the coupling between the relative amounts of each phase, interfacial energy relative to the two surface energies
and the equilibrium conditions at the tri-junction. These features can be used to find the ratio of the interfacial energy
to the surface energies of two-phase particles for any state of matter. 相似文献
949.
Reaction models are proposed to quantify the hydration products and to determine the composition of C–S–H from alkali-activated
slags (AAS). Products of the slag hydration are first summarized from observations in literature. The main hydration products
include C–S–H, hydrotalcite, hydrogarnet, AFm phases (C4AH13 and C2ASH8) and ettringite. Then, three stoichiometric reaction models are established correlating the mineral composition of slag (the
glass part) with the hydration products. Using the proposed models, quantities of hydration products and composition of C–S–H
are determined. The models are validated with a number of experimental investigations reported in literature, yielding good
agreement, i.e., these models can successfully predict the hydration reaction of AAS. The models are furthermore applied to
calculate the retained water in the hydration products of AAS in different hydration states and a general hydration equation
of AAS is derived. As an illustration to one of the model applications, chemical shrinkage of the AAS cement paste in different
hydration states are predicted. The chemical shrinkage of AAS is shown to be remarkably higher than OPC. Furthermore, phase
distribution in the hardened AAS paste and the porosity are calculated. 相似文献
950.
The effect of varying normalising and hardening temperatures on the prior austenite grain size in a low alloy Cr–Mo–Ni–V steel
has been examined. An initial relative insensitivity of grain size to increasing austenitising temperature was observed followed
by a sudden growth of grains at approximately 1000 °C. A detailed study of the precipitates in the steel showed the presence
of a bimodal size distribution of vanadium carbides. The grain size increase is attributed to a decrease in volume fraction
and an increase in size of V4C3 particles with increasing temperature. 相似文献