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Xie J.,Anhui University of Science and Technology | Wu C.,Anhui University of Science and Technology | Hu S.,Shanghai Supercomputer Center | Dai J.,Anhui University of Science and Technology | And 4 more authors.
Physical Chemistry Chemical Physics | Year: 2012

Modulating the interaction between small gas molecules and solid host materials is becoming increasingly important for the future society due to the alternative energy resources especially for the hydrogen energy. As is known, two catalogues of materials such as two-dimensional (2D) lamellar cavity structures and three-dimensional (3D) infinite tunnel structures have received intensive considerations during the past decades. Herein, we put forward a new alternative that the solid materials with synergic effects of grain-boundary-rich (GBR) structure and 3D hierarchical hollow structure would also be a promising candidate for modulating the gas molecules in solid adsorbents. As expected, our constructed novel 3D hollow hierarchitectures with GBR shells standing on the hollow spherical cavity indeed resulted in the enhanced hydrogen adsorption behavior. The as-prepared 3D hollow hierarchitectures were very uniform in large scale, and the very simple reaction process offers high convenience, short reaction time, and no need for any complex manipulations or equipments. The hollow outlook of the rutile VO 2(R) 3D hierarchitectures is the reminiscence of the hollow cavity of nsutite-type VO 2, while the formation of the VO 2(R) GBR structure is attributed to volume shrink from a unique intergrowth structure of nsutite-type VO 2. The novel gas modulation model with the synergic effect of GBR structure and hierarchical hollow structure may pave a new way for developing materials in energy and environmental fields in the near future. © 2012 the Owner Societies. Source

Feng J.,Anhui University of Science and Technology | Sun X.,Anhui University of Science and Technology | Wu C.,Anhui University of Science and Technology | Peng L.,Anhui University of Science and Technology | And 4 more authors.
Journal of the American Chemical Society | Year: 2011

With the rapid development of portable electronics, such as e-paper and other flexible devices, practical power sources with ultrathin geometries become an important prerequisite, in which supercapacitors with in-plane configurations are recently emerging as a favorable and competitive candidate. As is known, electrode materials with two-dimensional (2D) permeable channels, high-conductivity structural scaffolds, and high specific surface areas are the indispensible requirements for the development of in-plane supercapacitors with superior performance, while it is difficult for the presently available inorganic materials to make the best in all aspects. In this sense, vanadium disulfide (VS2) presents an ideal material platform due to its synergic properties of metallic nature and exfoliative characteristic brought by the conducting S-V-S layers stacked up by weak van der Waals interlayer interactions, offering great potential as high-performance in-plane supercapacitor electrodes. Herein, we developed a unique ammonia-assisted strategy to exfoliate bulk VS2 flakes into ultrathin VS2 nanosheets stacked with less than five S-V-S single layers, representing a brand new two-dimensional material having metallic behavior aside from graphene. Moreover, highly conductive VS2 thin films were successfully assembled for constructing the electrodes of in-plane supercapacitors. As is expected, a specific capacitance of 4760 μF/cm2 was realized here in a 150 nm in-plane configuration, of which no obvious degradation was observed even after 1000 charge/discharge cycles, offering as a new in-plane supercapacitor with high performance based on quasi-two-dimensional materials. © 2011 American Chemical Society. Source

Miao X.,Shanghai JiaoTong University | Jin X.,Shanghai JiaoTong University | Ding J.,Shanghai Supercomputer Center
Nongye Jixie Xuebao/Transactions of the Chinese Society for Agricultural Machinery | Year: 2015

An efficient condensation parallel computing method for finite element structural analysis was proposed based on the sparse storage techniques and direct sparse solvers. In the proposed method, the process of condensation was converted to the process of solving a series of linear equations, and then the linear equations were solved with a direct sparse solver. It can avoid the storage and computation of many zero elements within the bandwidth in the traditional parallel computing method with variable bandwidth format condensation. Therefore, the memory space can be greatly saved and the amount of computation can be effectively reduced. Finally, the experiment of the finite element numerical simulation for an engine crankshaft was used to validate the proposed method. Test results showed that, compared with the conventional parallel computing method with variable bandwidth format condensations, the proposed parallel computing approach with sparse storage format condensation could considerably save memory space and significantly improve computational efficiency. The larger the size of each subdomain, the effect of the proposed method on aspects of saving memory space and improving computational efficiency was more obvious. The proposed method can be applied to many industrial areas such as aerospace, automobile, energy, civil and architecture to significantly improve the efficiency of engineering design and analysis. ©, 2015, Chinese Society of Agricultural Machinery. All right reserved. Source

Miao X.,Shanghai JiaoTong University | Jin X.,Shanghai JiaoTong University | Ding J.,Shanghai Supercomputer Center
International Journal of High Performance Computing Applications | Year: 2015

In order to improve the parallel efficiency of large-scale structural dynamic analysis, a hierarchical approach adapted to the hardware topology of multi-core clusters is proposed. The hierarchical approach is constructed based on the strategies of two-level partitioning and two-level condensation. The data for parallel computing is first prepared through two-level partitioning to guarantee the load balancing within and across nodes. Then during the analysis of each time step, the convergence rate of interface problem is significantly improved by further reducing its size with two-level condensation. Furthermore, the communication overheads are considerably reduced by separating the intra-node and inter-node communications and minimizing the inter-node communication. Numerical experiments conducted on Dawning-5000A supercomputer indicate that the hierarchical approach was superior in performance compared with the conventional Newmark algorithm based on the domain decomposition method. © SAGE Publications. Source

Cao Y.,Shanghai JiaoTong University | Wang P.,Shanghai Supercomputer Center | Jin X.,Shanghai JiaoTong University | Wang J.,Shanghai JiaoTong University | Yang Y.,Shanghai JiaoTong University
Tunnelling and Underground Space Technology | Year: 2012

Structure analysis of the long tunnel is difficult due to the lack of available computing power. Water hammer simulation in the water conveyance tunnel is also complicated because of strong fluid structure interactions (FSIs). In this paper, the multi-scale modeling method is used to simulate water hammer impacts in the long tunnel. The method can not only yield water hammer simulations along the full tunnel length, but also the detailed structural responses of the segment linings. In the proposed partitioned approach, the structural field is solved with the finite-element program LS-DYNA. The fluid field is solved with the CFD software package FLUENT. The interaction between two physical fields is realized using ALE description. A practical case study is presented and the results are discussed in detail. The results provide us with a better understanding of water hammers and their effects on tunnel linings. © 2011 Elsevier Ltd. Source

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