ISSN 0253-2778

CN 34-1054/N

2016 Vol. 46, No. 12

Display Method:
Original Paper
On weakly Π-embedded subgroups of finite groups
ZHANG Li, LIU Yufeng
2016, 46(12): 969-975. doi: 10.3969/j.issn.0253-2778.2016.12.001
Let G be a finite group and H a subgroup of G. H is called weakly Π-embedded in G if there exists a subgroup pair (T, S), where T is a quasinormal subgroup of G containing HG and S/HG≤H/HG satisfies Π-property in G/HG, such that |G:HT| is a power of a prime and (H∩T)/HG≤S/HG. Here weakly Π-embedded subgroups were used to explore the structure of finite groups. In particular, new criterions of hypercyclically embedded subgroups were obtained.
On integrable non-canonical geodesic flow on two-dimensional torus
2016, 46(12): 976-980. doi: 10.3969/j.issn.0253-2778.2016.12.002
A non-canonical metric on two-dimensional torus was introduced. It was proved that its geodesic flow is Liouville integrable and has vanishing topological entropy when restricted onto invariant hypersurface.
Improvement of the numerical condition of chromaticity on complete tripartite graphs
XU Limin, YANG Zhilin
2016, 46(12): 981-987. doi: 10.3969/j.issn.0253-2778.2016.12.003
Let P(G, λ) be the chromatic polynomial of a graph G. A graph G is chromatically unique if for any graph H, P(H, λ)=P(G, λ) implies G≌H. By comparing the number of the triangular subgraph and that of the quadrangular subgraph without chords, the chromatic uniqueness on the tripartite graph K(n-k,n-v,n) was discussed. It was proved that K(n-k,n-v,n) is chromatically unique for n≥v2(k-v/3)/4+v and k≥v≥2 and that K(n-k,n-2,n) is chromatically unique for n≥k+2,k≥2.
Development of a superconducting magnet for relativistic backward-wave oscillator
HUANG Pengcheng, FANG Zhen, GAO Yang, CHEN Wenge
2016, 46(12): 988-992. doi: 10.3969/j.issn.0253-2778.2016.12.004
A homogeneous magnetic field superconducting magnet with a room-temperature bore of 30 mm and a central field of 551 T for relativistic backward-wave oscillator was designed, manufactured and tested. As a result of magnetic field homogeneity considerations, the magnet is composed of three coaxial coils. All coils are connected in series and charged with a single power supply. The magnetic field homogeneity is better than ±05% from -30 mm to 30 mm in axial direction. The magnet can be operated in persistent mode with a superconducting switch. In addition, a pair of HTS current leads and a two-stage GM cryocooler with cooling capacity of 15 W at 42 K were adopted to realize a zero liquid helium boil-off. Here the design, manufacture, mechanical behavior analysis, and the test results of the magnet were presented.
The maximum electricity efficiency of hydrogen fueled fuel cell system
YANG Jianxin, LIN Zijing
2016, 46(12): 993-998. doi: 10.3969/j.issn.0253-2778.2016.12.005
Based on the fundamental definition of the electrical efficiency and the thermodynamics principle, a theoretical expression for the maximum electricity efficiency of a fuel cell system was derived. The characteristics of cell voltage operating at the maximum electrical efficiency and the energy required for heating the fuel and air were considered in deriving the maximum electricity efficiency expression. The values of the maximum electricity efficiency for hydrogen fuel at different operating temperatures were presented. The relationships between the maximum electricity efficiency and the working temperature, fuel utilization and the fuel steam content were analyzed.
A general theoretical model for the reaction rate of Ni catalyzed methane steam reforming reaction
ZHANG Xiaoyu, LIN Zijing
2016, 46(12): 999-1006. doi: 10.3969/j.issn.0253-2778.2016.12.006
Methane steam reforming (MSR) reaction rate is an important factor affecting the performance of methane fueled solid oxide fuel cell (SOFC). Ni is the most common catalyst for MSR in SOFC. There are large discrepancies in the Ni catalyzed MSR kinetic models proposed by different experiments. Moreover, the experiments for all the MSR kinetic models use methane with relatively high steam content, rendering the kinetic models unsuitable for the study of low steam methane fueled SOFCs.The major MSR kinetic models are surveyed here with the analysis of their similarities and differences. Based on the analysis and a new MSR kinetic model found for methane with low steam content, a unifying MSR kinetic model applicable for any steam content was deduced. The model is capable of explaining the confusion phenomenon that different steam reaction orders are observed by different experiments. It also provides good fits to the experimental data obtained under conditions such as different steam compositions and different working temperatures.
Investigation on morphology control of the nanoporous nickel phosphate
NIE Shibin, DONG Xiang, ZHANG Chi, ZHOU Can, HU Yuan
2016, 46(12): 1007-1014. doi: 10.3969/j.issn.0253-2778.2016.12.007
VSB-1 was synthesized by hydrothermal method in various synthesis conditions, and the influences of the synthesis conditions on the morphology of VSB-1 were studied. The results show that by adjusting the synthesis conditions, different morphologies of VSB-1 can be obtained. The morphology of VSB-1 changes from a needle-like to mushroom-like shape and the diameter of the VSB-1 also varies. The morphologies influence the surface areas of VSB-1.The needle-like VSB-1 has a higher BET (Brunauer-Emmet-Teller) surface than that of mushroom-like VSB-1. Meanwhile , the results show that VSB-1 has high thermal stability.
A Schiff base fluorescence probe for Cu2+ ion in CH3CN/H2O
DING Jinjin, ZHANG Yuhuan, SONG Xinkuan, YANG Qingqing, WANG Yipu, MA Danyang, TANG Yanfeng, SUN Tongming, ZHU jinli
2016, 46(12): 1015-1021. doi: 10.3969/j.issn.0253-2778.2016.12.008
A Shiff base (2′4′-dihydroxyl phenylideneimino)-2-naphthol (L) was synthesized from 1-amino-2-naphthol and 2,4-dihydroxybenzaldehyde. The aim compound was characterized by FT-IR, HNMR and ESI-MS. In the solution of V(CH3CN):V(HEPES)=1:1 at pH 7.2, the fluorescence responses of L to many metal ions (Cu2+, Hg2+, Ag+, Pb2+, Cd2+, Zn2+, Ni2+, Co2+, Fe2+, Al3+, Mn2+, Ca2+, Mg2+, K+, Na+) were studied. The results indicate that L displays a fluorescence quenching for Cu2+ with good selectivity and without obvious interferences by other metal ions. In the concentration range of Cu2+ from 0 to 25×10-5 mol/L, the fluorescence intensity of this solution shows a good linear relationship with the concentration of Cu2+. Based on this curve, the binding constant between L and Cu2+ is 333×104 L/mol, and the detection limit of L for Cu2+is calculated to be 4.92×10-7 mol/L.In natural water, L also shows a good linearity with Cu2+ in the concentration range of Cu2+ from 0 to 25×10-5 mol/L.
Service quality standard and pricing decision for wedding-car leasing platforms
LI Du, HE Ping
2016, 46(12): 1022-1029. doi: 10.3969/j.issn.0253-2778.2016.12.009
Typically, wedding-car leasing platforms gather a number of wedding-cars together and then provide service for clients. Besides pricing for both sides of platforms under the consideration of two-sided network externalities, the service quality provided by platforms is also important. A dynamic game model was built to investigate the trade-offs of pricing decision and service quality. Two distinct settings, charge fees by the cost of one car and charge fees by total cost, were considered. By analyzing the model the optimal service quality and optimal pricing decision were obtained, and the effects of customer and wedding-car externalities on optimal service quality and optimal pricing decision were revealed.
Two-sided platforms performance investment and pricing
2016, 46(12): 1030-1035. doi: 10.3969/j.issn.0253-2778.2016.12.010
In the development of two-sided platforms, managers of platforms must decide what level of platform performance to invest. Higher performance is helpful to attract more users, but it often requires developers to make large investment to participate. Based on this, a model was established to explore platforms performance investment and pricing. The result shows that platforms performance investment and pricing are driven by two different expectations, favorable and unfavorable expectation. Under favorable expectation, managers only need to find the optimal performance and pricing according to investment profit function; under unfavorable expectation, managers can adopt seller subsidy strategy or buyer attraction strategy to eliminate the unfavorable expectations and maximize profits.
Impact of spillover effect of exchange rate volatility on capital market
CAI Qiang, LI Yong
2016, 46(12): 1036-1040. doi: 10.3969/j.issn.0253-2778.2016.12.011
With the deepening of the reform of foreign exchange management system in China, the effect of increasing volatility of the RMB exchange rate on the capital market is more and more significant. The index of spillover effect between capital markets in China was built based on the improved VAR model. The impact of spillover effect of exchange rate volatility on capital market was empirically analysed. The results show that the impact of spillover effect is asymmetric among the different volatility level samples of RMB exchange rate, and low volatility of exchange rate has the most significant impact of spillover effect; and that the empirical results also confirmed that the exchange rate volatility may lead to the bidirectional spillover effect on capital market.