ISSN 0253-2778

CN 34-1054/N

2017 Vol. 47, No. 2

Display Method:
The Hermitian-Yang-Mills flow on Higgs sheaves
LI Jiayu, ZHANG Chuanjing, ZHANG Xi
2017, 47(2): 87-98. doi: 10.3969/j.issn.0253-2778.2017.02.001
Higgs sheaves were introduced by Hitchin at 1980’s. They they have a rich structure and play a role
The research and development of dynamic creatures design based on mechanics
DU Dong, WANG Shiwei, LIU Ligang
2017, 47(2): 99-116. doi: 10.3969/j.issn.0253-2778.2017.02.002
To break the confines of the traditional dynamic creatures design, researchers have proposed a new computable, interactive and “motion-to-form” design method, combined with material analysis, kinematic and mechanics simulation, model segmentation, structural analysis and layout, collision detection, and rapid 3D printing prototyping technology to automatically simulate the dynamic structure design and manufacturing process. It allows causal users to design and fabricate their personal dynamic creatures with rich motion, which greatly simplifies the structural design and saves the design costs. Although computational dynamic mechanics design has made great progress, it is still facing many challenges, such as physical simulation, mechanical analysis, environmental perception, etc. This review divides the existing research into micro, meso and macro multi-scale structure design based on the differences in material selection and structural design. Since the macro-scale design is the hottest, we further divide it into motion-driven, shape-driven and functioning-driven mechanics design, and introduce their features and shortcomings respectively. The future research of dynamic mechanics design is also discussed with the combination of emerging technology, user experience and scene applications.
Quantum simulation of topological phases of quantum matter with nuclear magnetic resonance
LUO Zhihuang, PENG Xinhua
2017, 47(2): 117-128. doi: 10.3969/j.issn.0253-2778.2017.02.003
Topological phases are exotic states of quantum matter which are beyond the usual symmetry description. These phases have some interesting properties, such as robust ground state degeneracy that depends on the surface topology, quasiparticle fractional statistics, topological entanglement entropy, etc. Topological phases not only play a significant role in the basic scientific research of condensed matter physics, but also provide a natural medium for fault-tolerant quantum computation. Quantum simulation suggests that the complicated or inaccessible physical phenomena can be simulated by a controlled quantum system, which will provide a powerful means to explore topological phases and their topological properties. Nuclear magnetic resonance, as one physical implementation of quantum simulation, is a good test platform due to its sophisticated control and precise measurement in multi-qubit experiments. In this paper, topological phases and nuclear magnetic resonance quantum simulator are reviewed, and three related experiments on quantum simulation of topological phases are introcluced. Finally, a summary and an outlook towards topological quantum computation are given.
Research progress in construction of three-dimensional carbon materials based on sp2 hybridization
ZHU Yanwu, TAO Zhuchen, NI Kun
2017, 47(2): 129-141. doi: 10.3969/j.issn.0253-2778.2017.02.004
sp2 hybridization is one of the most important forms of carbon-carbon bondings, and the threefold symmetry related to the bonding has led to the formation of stable graphite structure and meso-stable structures of fullerenes, carbon nanotubes and graphene. The electrons that are not involved in the hybridization form π bonds with good electric conductivity and other unique electronic properties especially in carbon nanostructures. With exotic physical, chemical and biological properties, sp2 hybridized carbon nanomaterials have attracted great attention and are expected to be applied in the fields of electronics, energy, biomedical, pharmaceutical, functional materials, etc. In the present many studies, the above-mentioned nanomaterials often need to be constructed into three-dimensional materials so as to exhibit the superior characteristics of the nanomaterials on a larger scale. This paper presents a review of the recent advances in three-dimensional materials based on sp2 hybridized carbons, and give comments on the interaction between the building blocks and factors involved in the construction.
Research progress of micro/nano mechanical problems in unconventional oil and gas exploitation
FAN Jingcun, YU Hao, CHEN Jie, LI Xiangzhe, WANG Fengchao, WU Hengan
2017, 47(2): 142-154. doi: 10.3969/j.issn.0253-2778.2017.02.005
Unconventional oil and gas resources have a promising development prospect due to their abundant reserves. The exploitation of them involves a series of micro/nano mechanical problems. To enhance the oil recovery, polymer flooding and nanofluid flooding are employed. The microscopic displacement mechanisms of these two methods have attracted wide attention. Shale gas, which is stored in adsorbed state and bulk state in the micro/nano pores of shale, flows into the fractures with the displacement of injection gases. Recent research progress of micro/nano mechanical problems in unconventional oil and gas exploitation based on our previous study was reviewed. The microscopic displacement mechanisms of polymer and nanofluid flooding were discussed. Then, the adsorption of shale gas, displacement of injection gases and the mechanisms of micro flow were reviewed. Finally, the direction and key point of future work were discussed.
Experimental investigation of electrical conductivity of silicate melts: Implications for melting in Earth’s interior
NI Huaiwei, GUO Xuan
2017, 47(2): 155-162. doi: 10.3969/j.issn.0253-2778.2017.02.006
As silicate melts are electrically more conductive than solid minerals, molten zones in Earth’s interior, such as magma chambers, show anomalies in electrical structure inversed from magnetotelluric survey. To constrain the physicochemical conditions, such as melt fraction and H2O concentration in the melt, of the molten zones, experimental data are urgently needed as to the electrical conductivity of the various silicate melts at different temperatures, pressures and H2O concentrations. This paper reviews the progress in experimental studies of electrical conductivity of silicate melts. The concentration of Na+ and that of H2O are the key factors in controlling electrical conductivity. Two applications include the oceanic asthenospheric low-velocity zone and the magma chamber beneath the Tianchi Volcano, Changbai Mountain. Potential future research directions include electrical investigation of supercritical fluids, which could be deemed as a special type of H2O-rich silicate melt, and determination of melting temperature by using jump in electrical conductivity as an index.
Progress in the study of subduction initiation
2017, 47(2): 163-175. doi: 10.3969/j.issn.0253-2778.2017.02.007
Subduction initiation is one of the most important processes of tectonic evolution of the Earth. Since the tectonic theory was proposed about five decades ago,studies of subduction initiation have been performed for a long time. In early time, a variety of theoretical models were proposed to describe such a process and evaluate the model controlling parameters. Some of the tectonic phenomena can be explained based on these models. Meanwhile, important physical properties of rocks were measured in laboratory, which provided a series of possible conditions for temperature, pressure and rheological parameters. Based on these preliminary results, numerical simulations were conducted to study the mechanism of subduction initiation. There have been two basic theoretical models proposed for subduction initiation. Numerical simulations investigated parameterization of the theoretical models based on the conservation of mass, momentum and energy equations. Results from numerical models discuss the roles of different controlling parameters in the evolution of subduction initiation, which explain the geological observations to some extent. However, since there are limitations on the numerical simulations and critical hypotheses for the basic models,current results remain obscure for clearly understanding the process. With the increases of geological observations and technical development for numerical simulations,it will be possible to better explain the mechanism of subduction initiation and plate tectonics. This paper is a summary of the advancements for the mechanism of subduction initiation in the last tens of years. Also, the divergent evolutionary processes of subduction initiation resulting from recent numerical simulations are discussed. Finally, possible directions for future studies of subduction initiation are proposed.
Recent advances on researches of warehousing, logistics and supply chain management
LIU Bingbing, SUN Libo, YU Yugang
2017, 47(2): 176-187. doi: 10.3969/j.issn.0253-2778.2017.02.008
Theories and methodologies adopted in warehousing, logistics and supply chain are the bedrock for the rapid development of global economy and commercial activities. Such theories and methodologies attract researchers’ attention due to their complexity and practicability. In this paper, our achievements in these fields are introduced: warehousing theory and optimization methods (especially next generation compact warehousing system), scheduling yard cranes in a container block and minimizing total travel time in a two-depot automated S/R system, minimizing the expected number of reshuffles at a container terminal and optimal mechanisms design in vendor-managed-inventory (VMI) supply chains. Then, combining the technology of Internet of things, some perspects are given on future directions of warehousing, logistics and supply chain management.
Design and demonstration of an improved visible light positioning system based on RSS
ZENG Mian, GONG Chen, XU Zhengyuan
2017, 47(2): 188-194. doi: 10.3969/j.issn.0253-2778.2017.02.009
An improved visible light positioning (VLP) system based on received signal strength (RSS) was proposed and experimentally demonstrated. It was assumed that the adjacent LEDs transmit information in different time slots to eliminate mutual interference. The Lambertian-based positioning method was evaluated via both simulations and experiments. Based on experimental measurements, the indoor positioning accuracy can reach the order of centimeters. In particular, the improved algorithm shows lower computational complexity and good robustness to the peak-to-peak voltage difference of different LEDs.