A Classification of Minimal Non-MNP-Groups

A finite group G is called an MNP-group if all maximal subgroups of every Sylow subgroup of G are normal in G. In this article, we give a complete classification of those groups which are not MNP-groups but all of whose proper subgroups are MNP-groups.     

时滞信用风险下的幂交换期权定价

本文在约化模型的框架内考虑了含信用风险的幂交换期权定价,在"市场价值回复"假设下,给出了时滞信用风险下幂交换期权的定价公式.     

Performance of an oscillating subsoiler in breaking a hardpan

A single shank tractor mounted oscillating subsoiler was developed to break hardpan, common in sugarcane (Saccharum officinarum) farms especially after harvest when heavy trucks transport the cut canes from the field to the sugar factory. Field experiments were conducted to determine the optimum combination of performance parameters of the subsoiler. Field tests were conducted at frequencies of oscillation of 3.7, 5.67, 7.85, 9.48 and 11.45 Hz; amplitudes of 18, 21, 23.5, 34 and 36.5 mm; and forward speeds of 1.85, 2.20 and 3.42 km h⁻¹ at moisture contents close to the lower plastic limit of the clay soil. A reduction in draft but an increase in total power requirement was found for oscillating compared to non-oscillating subsoiler. The draft and power ratios were significantly affected by the forward speed, frequency and amplitude. Their combined interaction, expressed in terms of the velocity ratio (the ratio of peak tool velocity to forward speed), however, had the strongest influence. At the same velocity ratio, the draft reduction and power increase were less at higher amplitude of oscillation. For the field conditions tested, the optimum operation for least energy expenditure was obtained at an amplitude of 36.5 mm, frequency of 9.48 Hz and speed of 2.20 km h⁻¹ with a draft ratio of 0.33 and power ratio of only 1.24. It could be concluded that the oscillating subsoiler reduces draft for breaking hardpan, reduces soil compaction and promotes the use of lighter tractors by utilizing tractor power-take-off (p.t.o.) power to achieve higher efficiency of power transmission. ©     

Simulation and evaluation of phase noise for optical amplification using semiconductor optical amplifiers in DPSK applications

A thorough simulation and evaluation of phase noise for optical amplification using semiconductor optical amplifier (SOA) is very important for predicting its performance in differential phase-shift keyed (DPSK) applications. In this paper, standard deviation and probability distribution of differential phase noise at the SOA output are obtained from the statistics of simulated differential phase noise. By using a full-wave model of SOA, the noise performance in the entire operation range can be investigated. It is shown that nonlinear phase noise substantially contributes to the total phase noise in case of a noisy signal amplified by a saturated SOA and the nonlinear contribution is larger with shorter SOA carrier lifetime. It is also shown that Gaussian distribution can be useful as a good approximation of the total differential phase noise statistics in the whole operation range. Power penalty due to differential phase noise is evaluated using a semi-analytical probability density function (PDF) of receiver noise. Obvious increase of power penalty at high signal input powers can be found for low input OSNR, which is due to both the large nonlinear differential phase noise and the dependence of BER vs. receiving power curvature on differential phase noise standard deviation.     

托卡马克芯区Zeff测量和分析方法的研究

基于等离子体锯齿弛豫振荡的测量和研究,结合芯区电子功率平衡的分析,获得一种可靠的确定芯区平均有效离子电荷数Zeff的测量方法。该方法不受杂质的限制,测量条件十分容易满足。     

Aziridine-functionalized graphene: Effect of aromaticity for aryl functional groups on enhanced power conversion efficiency of organic photovoltaic cells

We have demonstrated the covalent functionalization of graphene by nitrene chemistry, resulting in highly dispersed aryl azides functionalized graphene. Two different ortho-substituted aryl azides having different aromatic ring (π-conjugation) and ester/anhydride substituent have been synthesized. Further, on thermolysis they undergo [2+1] cycloaddition ensuing in the formation of aziridine adduct with sp² carbons of graphene. Resulting aryl azide functionalized graphene sheets (f-graphene I & II) are soluble in most common organic (polar and non polar) solvents, facilitating the structural/property characterization and the device fabrication by solution processing. The aziridine linkage modification of the π conjugation and the strong electronic interaction between the f-graphenes and poly (3-hexylthiophene) (P3HT):Phenyl-C₆₁-Butyric-Acid-Methyl Ester (PCBM) has been confirmed by various spectroscopic analysis. The implications of changing the aromaticity of the aryl azides attached to f-graphenes on the P3HT:PCBM bulk heterojunction (BHJ) photovoltaic device are discussed. The solution cast f-graphene I (5%) doped P3HT:PCBM BHJ showed the power conversion efficiency ? = 1.94( ± 0.06) %, while f-graphene II (5%) doped exhibited ? = 2.16( ± 0.07) % under AM 1.5 illumination (100 mW/cm²), which is found to be more than double the efficiency of the reference cell.     

图犹豫模糊Power Heronian平均算子及其在多属性决策中应用

针对需要同时考虑属性关联性及整体均衡性多属性决策问题,联合图犹豫模糊集对于不确定信息的表达优势,提出一种基于图犹豫模糊Power Heronian平均算子的多属性决策方法。首先,给出图犹豫模糊数的得分函数、精确函数及距离公式;在此基础上,提出图犹豫模糊Power Heronian平均算子和图犹豫模糊Power加权Heronian平均算子;最后,将所提算子应用于多属性决策问题中,验证所提算子的有效性和可行性。