Papers by Keyword: Structure

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Authors: Alexander Tkach, Branca Araújo, Paula M. Vilarinho
Abstract: The effect of the electric field on the dielectric response of the Sr1-xCaxTiO3 ceramic system was analysed and complemented by structural and microstructural studies. A monotonic decrease of the lattice parameter and an increase of the average grain size from 11 to 23 μm with increasing x were observed by X-ray diffraction and scanning electron microscopy analysis respectively. Samples with x = 0.003 and 0.01 reveal a monotonous increase of low-temperature dielectric constant, corresponding to an enhancement of the tunability and a reduction of the driving electric field at 10-30 K for x = 0.01. For Sr1-xCaxTiO3 ceramic samples with x = 0.04 and 0.10 the ferroelectric phase transition of around 20 K was observed together with the enhanced tunability of the dielectric constant at 30-85 K for x = 0.10.
240
Authors: Jörg C. Sturm, Wilfried Schäfer
Abstract: During the last 25 years, casting process simulation has developed from predicting hot spots and solidification paths to an integral assessment and optimization tool for foundries for the entire manufacturing route of castings. Modeling cast irons has always been a special challenge due to the strong interdependency between the alloy composition, applied metallurgy and metal treatment with the solidification, phases and structures which form and the resulting properties of the material.
451
Authors: Qing Bo Wang, Cui Zhou
Abstract: We researched the effect of single intrinsic defect of the structure and electronic properties of V-doped ZnO. After vanadium (V) atom replaced one zinc atom, lattice constants and bulk modulus increased slightly 1.2% and as high as 8.9%, respectively. The total energy showed that oxygen defect inclined to stay at a position far from V atom but zinc defect likely to localize at a position near V atom. The electronic density state of pure ZnO was semiconductor behavior. Vanadium doping introduced a spin-polarization around Fermi-level. The 3d orbital of V split into triplet-state ta (antibonding state), dual-state e (nonbonding state) and triplet-state tb (bonding state) in the wurtzite ZnO crystal field. The ta state hybridized with O2p state above Fermi-level, which made Zn15VO16 underwent a semiconductor-halfmetal transition. Vanadium substitution moved the electronic density states to lower energy. Oxygen defect had little effects on V-doped ZnO while zinc defect moved the density of states to higher energy. Our paper provided a reference for the preparation and application of V-doped ZnO.
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Authors: Fu Zeng Ren, Yang Leng, Xiong Lu
Abstract: ab initio simulations were employed to investigate the crystal structure of carbonated apatite (CAp). Two possible sites for the carbonate ions in the apatite lattice were considered: carbonate substituting for OH- ion (type-A) and for PO43- ion (type-B). A combined type-AB substitution was also proposed and numerous possible charge compensation mechanisms were treated. The results show that the most stable type-A CAp had its carbonate triangular plane almost parallel to c-axis, making an angle of about 2° at z = 0.46. In the most stable type-B CAp structure, the nearest Ca (2) ion was replaced by a sodium ion and the carbonate group was lying almost flat in b/c-plane. Of all the models considered, mixed substitution type-AB where two carbonate ions replacing one phosphate group and one hydroxyl group shows the most stable structure.
1
Authors: Cheng Liu, Zhe Li, Hui Wang, Lei Xia
Abstract: Nowadays we advocate low carbon economy, energy conservation and emission reduction, emphasize the harmonious development of human being and the nature. As a result, the clean, efficient microgrid with flexible use mode is widely payed attention to. A microgrid uses natural resources as electric power source, it can effectively relieve burden of the grid, and help to solve the problem of transporting electricity from the grid to remote suburb area. How to design the structure of a microgrid to make it run harmoniously with the grid while using clean energy efficiently and controlling the microgrid reasonably is the key to developing microgrid technique. Based on the construction of microgrids in China, this paper concludes the main key techniques in designing and constructing of microgrid, introduces several typical microgrids in China, and makes an outlook to the designing of microgrid structure and technique development.
931
Authors: Sergey Prokoshkin, Vladimir Brailovski, Karine Inaekyan, Andrey Korotitskiy, Sergey Dubinskiy, Mikhail R. Filonov, Mikhail Petrzhik
Abstract: The processes of structure formation in Ti-Ni and in Ti-Nb-Zr, Ti-Nb-Ta shape memory alloys (SMA) under thermomechanical treatment (TMT) were studied. The TMT comprised cold rolling with true strains from e=0.25 to 2 and post-deformation annealing. Differences in these processes between two groups of alloys are considered. The main conclusions are as follows: nanostructures created by TMT are useful for radical improvement of the SMA functional properties, and an optimum nanostructure (nanocrystalline structure, nanosubgrained structure or theirmixture) should be selected by taking into account other structural and technological factors.
1931
Authors: Xiao Yi Li, Zhao Di Xu, Wan Xi Chou
Abstract: This paper proposed the basic idea of constructing method of large v order Steiner four elements large set under the blow of steiner three elements. At the same, this paper analyzed the conditions for the existence of v order Steiner four elements. This paper also proposed the construction method of v order Steiner four elements large set based on the initial block matrix permutation. This paper also introduced the entire construction process of 9 order Steiner four elements systems large set. This paper proved the number of 9 order Steiner four elements s(1)(9)of 9 order Steiner four elements large set is d(9)=v-8=1 .
379
Authors: Ciro Faria Maia, Guilherme Silame Maranhão Lima, Felipe Grossi L. Amorim, Evandro Queiroz Nunes Vera, Alexander Matioli Pasqual
Abstract: The present paper presents a study of square-section tubes conditioned to a FE dynamic frontal impact analysis, considering a 10.0 m/s initial velocity against an infinitely rigid plane. A 50.0 kg punctual mass is positioned on center of the cross-sections, on the farthest side from the rigid plane and the deceleration pulse is measured along the simulations. After validating the numerical model with analytical solutions, the results are compared for four geometries with little structural differences in order to access the role of each difference on the geometry under crash situations. The results show that adding many triggers to the geometry may not be the best performance solution for crash boxes, since the geometry with few triggers achieved better values of deceleration peak than the others. In addition, the presence of holes showed to be an instability cause to the system. The structural solutions presented could be of great value for future vehicle crash box developments.
36
Authors: Yong Jian Zhao, Hai Ning Jiang, Mei Xia Qu
Abstract: This paper proposes a blind source extraction (BSE) method on the basis of several time-delay autocorrelations from primary sources. This method is a second-order statistic learning algorithm, which can extract a desired biomedical signal while it shows a specific temporal structure. In contrast to conventional BSE methods, it is simple and do not need to choose any learning step size. Computer simulations on biomedical measurements demonstrate its validity and high performance in the process of revealing the underlying desired signal.
3841
Authors: Ai Xia He, Rong Chang Li
Abstract: In order to reduce the cost of washing machine clutch, clutch manufacturing process to improve through conventional washing machine JLX-N-5.0 clutch structure analysis, a new structure of the washing machine clutch, in ensuring the technical performance of the major premise, the clutch brake structure was improved to cancel one-way bearing, narrow diameter brake wheel, change the brake means and planetary gear train positioned. Comparative experimental results show that the clutch brake performance and a substantial increase in operating performance, with simple technology and low cost characteristics.
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