ISSN 0253-2778

CN 34-1054/N

2014 Vol. 44, No. 3

Display Method:
Original Paper
Two results on the signless Laplacian matrix of a graph
WU Min, PAN Yongliang
2014, 44(3): 173-175. doi: 10.3969/j.issn.0253-2778.2014.03.001
Let G be a simple connected graph with n vertices and m edges and Q(G) its signless Laplacian matrix. The spectral radius and the entries of the principal vector of Q(G) were investigated.
The distance signless Laplacian spectral radius of trees with n-3 pendent vertices
YU Guidong, GONG Qijuan, DUAN Lan
2014, 44(3): 176-180. doi: 10.3969/j.issn.0253-2778.2014.03.002
The distance signless Laplacian spectral radius of a connected graph G is the spectral radius of the distance signless Laplacian matrix of G, defined as Q(G)=Tr(G)+D(G), where Tr(G) is the diagonal matrix of vertex transmissions of G, and D(G) is the distance matrix of G. It was investigated that the minimum of the distance signless Laplacian spectral radius among all trees with n-3 pendent vertices, and characterized that the unique tree whose distance signless Laplacian spectral radius is the maximum (minimum) among some trees with n-3 pendent vertices.
The threshold dividend strategy on a class of dual model with tax payments
LIU Zhang, WANG Wenyuan
2014, 44(3): 181-187. doi: 10.3969/j.issn.0253-2778.2014.03.003
A class of dual risk model was considered in which dividends are paid under a threshold strategy and tax payments are paid according to a loss-carry forward system. For this model, the expectation of the discounted dividends until ruin was investigated and their corresponding integral equations, integro-differential equations and analytical expressions were derived. Finally, the case where profits follow an Erlang(2) distribution was solved.
On optimal investment strategy of pension funds with a minimum guarantee under Knightian uncertainty
SHI Xueqin, FEI Weiyin, HU Huimin, BAO Pinjuan
2014, 44(3): 188-193. doi: 10.3969/j.issn.0253-2778.2014.03.004
A continuous-time stochastic control model of optimal management was proposed for a defined contribution pension fund with a minimum guarantee. A pension fund managers utility was characterized from the fund wealth on an infinite horizon by α-maxmin expected utility (α-MEU), by which he differentiates ambiguity and ambiguity attitude under Knightian uncertainty. Pension fund managers value function was derived by the stochastic control theory. The explicit expressions for both the optimal allocation strategy in feedback form and the value function which is a solution to the HJB equation were obtained.
Optimization of dynamic portfolio under model uncertainty
YU Minxiu, FEI Weiyin, LYU Huiying
2014, 44(3): 194-202. doi: 10.3969/j.issn.0253-2778.2014.03.005
The problem of optimal portfolio under model uncertainty and a general semimartingale market was studied. First, a solution to the investment problem was obtained using the martingale method and the dual theory. It was proven that under appropriate assumptions a unique solution to the investment problem exists and is characterized. Then, the value functions of the primal and dual problem are convex conjugate functions. Finally, a diffusion-jump-model was considered where the coefficients depend on the state of a Markov chain and the investor is uncertain about the intensity of the underlying Poisson process. For an agent with logarithmic utility function, the stochastic control method was adopted to derive the Hamilton-Jacobi-Bellmann-equation. Furthermore, the solution of the dual problem can be determined and it was shown how the optimal portfolio can be explicitly computed.
Constacyclic codes over Rk
SONG Xianmei, ZHU Shixin
2014, 44(3): 203-206. doi: 10.3969/j.issn.0253-2778.2014.03.006
Constacyclic codes over Rk were mainly discussed. It was proved that the image of a (1+uk)-constacyclic code of length n over Rk  under  is a binary quasi-cyclic of index 2k-1 and length 2kn. Rk[x]/(xn-(1+uk)) ring was studied. It was obtained that Rk,n is local when n=2m, that Rk,n is not local when n=2ms, where s>1 is an odd number.
A family of repeated-root constacyclic codes over F2+uF2+vF2
ZHANG Yuanting, ZHU Shixin
2014, 44(3): 207-213. doi: 10.3969/j.issn.0253-2778.2014.03.007
The (1+u)-cyclic codes of length 2k over the ring R=F2+uF2+vF2 were studied, and all such codes were classified. A formula for the number of these constacyclic codes was obtained.
Test a perturbative QCD prediction with e+e-→D*+D*-
GUO Han, ZHANG Ziping
2014, 44(3): 214-216. doi: 10.3969/j.issn.0253-2778.2014.03.008
The differential cross section for e+e-→D*+D*- process was calculated in terms of the electromagnetic form factors of D* meson. After putting in the ratios of form factors predicted by perturbative QCD (quantum chromodynamics), the angular distribution obtained was found to be inconsistent with experimental measurement at s=1058 GeV.
Lead glass calorimeter calibration and efficiency analysis for Coulomb sum rule (CSR) experiment in JLab Hall-A
YAN Xinhu, YE Yunxiu, LYU Haijiang, JIANG Fengjian, ZHU Pengjia, SHI Ying
2014, 44(3): 217-220. doi: 10.3969/j.issn.0253-2778.2014.03.009
Two layers of lead glass calorimeter are installed for additional PID analyses in each high resolution spectrometer (HRS) at Hall-A in Jefferson Lab (JLab). The Fumili minimization method of ROOT analysis software and quasi-elastic data of CSR experiment conducted by the authors in the early year of 2008 at JLab were used in the calibration of the calorimeter detector on HRS for the data analysis of CSR experiment. Since some high voltage changes in hardware settings, the lead glass calorimeter detector needed to be calibrated correspondingly. The calibration results are reasonable after this procedure. The best resolution of the calorimeter for the scattering electron was about 0048 GeV when its momentum was at 10 GeV after calibration. Total electron efficiency and pion rejection can reach 993% and 998%, respectively.
Surface interaction between Au nanoparticles and surfactants studied by XAFS
YIN Peidong, JIANG Yong, LI Yuanyuan, YAO Tao, SUN Zhihu, GE Mengran, PAN Guoqiang, WEI Shiqiang
2014, 44(3): 221-226. doi: 10.3969/j.issn.0253-2778.2014.03.010
X-ray absorption fine structure (XAFS) was used to study the atomic and electronic structure of Au nanoparticles affected by three kinds of surfactants, triphenylphosphine (PPh3), dodecanamine (C12H27N) and dodecanethiol (C12H26S). XAFS and TEM results indicate that the surface interaction intensity between Au nanoparticles and surfactants is in the order of C12H26S, C12H27N and PPh3. The head-group P atom in the PPh3 molecule is weakly bonded Au adatoms of Au nanoparticles, and the resulting nanoparticle size is about 72 nm. However, the head-group N atom in C12H27N and S atom in C12H26S are strongly bonded to Au adatoms, forming Au—N and Au—S covalent bonds, respectively, which effectively inhibits the aggregation of nanoparticles and leads to the smaller size of 31 nm. Furthermore, the bond length of the first nearest Au—Au coordination decreases from 282  for PPh3 capping to 279  for C12H26S capping, along with the decrease of Au—Au coordination number from 113 to 101, indicating the strongest interaction between C12H26S and Au nanoparticles. The XANES results indicate that the significant charge transfer of Au nanoparticles only occurs for the case of C12H26S capping.
Analysis of photon stochastic noise in X-ray microcopy
WU Luqi, GAO Kun, CHEN Jian, WU Ziyu
2014, 44(3): 227-232. doi: 10.3969/j.issn.0253-2778.2014.03.011
Stochastic photon noise is one of the most important factors which influence the quality of X-ray microscope images. The influence of the noise is described by the signal-to-noise ratio (SNR). Generally, increasing the number of photons yields better SNR, but inevitably with the side effect of a higher dose for the specimens. To find a good balance, one has to find a way to minimize the photon number while keeping an acceptable SNR, but conventional empirical Rose criterion is of little help, especially when applied to processed noised images. Here a concept of “probability-to-distinguish” was provided as an improvement on the Rose criterion. It can be used to find out the threshold of the photon number. The new method was applied to analyze noised images in image subtraction and compute the minimum photon number required. The conclusion is that objects can be distinguished from their background when the probability-to-distinguish is set at above 0.4.
Experimental study on flow characteristics at the initial injection stage of underwater supersonic gas jets
SHI Honghui, WANG Jianfeng, CHEN Shuai, DONG Ruoling
2014, 44(3): 233-237. doi: 10.3969/j.issn.0253-2778.2014.03.012
An experimental research was carried out to study three-dimensional underwater supersonic gas jets. The evolutionary process of initial bubble motion of the gas jets was analyzed, providing some comparable evidence for the results of prior numerical simulation. In addition, quantitative data of the initial bubble motion and some laws of the morphological change of the underwater gas jets by introducing the concept of non-roundness were given. This paper is presented as a useful reference for engineering practice.
Influence of silicon doping on mechanical properties of graphene sheets under tension
ZHAO Xiaoxi, LI Junhua, LI Xuyang, LIU Wei, LI Yongchi
2014, 44(3): 238-243. doi: 10.3969/j.issn.0253-2778.2014.03.013
Using Tersoff potential, the stretch process of silicon doped graphene sheets were simulated via molecular dynamics simulation. The influence of silicon doping on the tensile properties of graphene sheets were analyzed by changing the silicon doping ratios of the armchair and zigzag graphene sheets respectively, and the corresponding stress-strain relationships and tensile failure modes were obtained. The results indicate that silicon substitution in graphene has an obvious effect on its Youngs modulus, and that the ultimate tensile strain and tensile strength of grapheme sheets were significantly reduced due to the increase in silicon substitution ratios respectively.
The optimal portfolio with modified covariance matrix using clustering method
PAN Yang, CHENG Xijun
2014, 44(3): 244-247. doi: 10.3969/j.issn.0253-2778.2014.03.014
The Markowitz optimal portfolio was introduced and the reason why the result was unstable was analyzed.Based on this analysis, a new method was presented: Using the clustering method to modify the sample covariance matrix to get a better investment option. To prove the new methods reasonableness, real data from the Chinese stock market were used to simulate “real investment”. It was found that the portfolio obtained from this method was better in both mean return and stability than the traditional method, which can be further verified by using risk prediction.
Quasi-consistency of interval complementary judgment matrix and its weights
TU Zhenkun
2014, 44(3): 248-256. doi: 10.3969/j.issn.0253-2778.2014.03.015
Based on the idea of the relative superiority degree found in the additive consistency and the multiplicative consistency of fuzzy complementary judgment matrix (FCJM), the quasi-additive consistency and the quasi-multiplicative consistency of interval complementary judgment matrix (ICJM) were given. And they were merged into the quasi-consistency of ICJM by the complementary property of possibility degree. The problem of how to determine ICJM weights was analyzed under two conditions. In the condition of the IRJM with quasi-consistency, by the method of possibility degree an FCJM was derived from the comparison among its interval weights, and its precise value ranking vector was also achieved using the middle translation method. Then, under the condition of general ICJM, its interval weights were obtained by a deviation model which is established by the deviation between ICJM and its interval weights in the respect of possibility degree. And an FCJM was derived from the comparison among its interval weights, and its precise value ranking vector was also achieved using the middle translation method. And it was pointed out that the solution process of the former condition is in fact the specific one of the latter condition. A necessary and sufficient condition of the quasi-consistency of ICJM was achieved. Finally, the validity and the practicability of the proposed method were illustrated with an example.