偏振控制锁模光谱边带偏移量的计算及实验验证

通过对光纤中传输的孤子波演化及其色散波相互作用的动力学方程分析,详细推导了环形腔非线性偏振旋转(NPR)锁模光纤激光器中色散波与孤子波相互干涉而产生的脉冲光谱边带偏移量的理论计算公式.并将各级边带波长与脉冲中心波长的偏移量理论值与相应的实验测量值进行了对比,理论值与实验值符合得非常好,其最大误差在4.1%以下.从而解释了在偏振控制被动锁模条件下,环形腔光纤激光器光谱边带产生的原因.     

A low-power 10-bit 250-KSPS cyclic ADC with offset and mismatch correction

A low power 10-bit 250-k sample per second(KSPS) cyclic analog to digital converter(ADC) is presented. The ADC’s offset errors are successfully cancelled out through the proper choice of a capacitor switching sequence.The improved redundant signed digit algorithm used in the ADC can tolerate high levels of the comparator’s offset errors and switched capacitor mismatch errors.With this structure,it has the advantages of simple circuit configuration,small chip area and low power dissipation.The cyclic ADC manufactured with the Chartered 0.35μm 2P4M process shows a 58.5 dB signal to noise and distortion ratio and a 9.4 bit effective number of bits at a 250 KSPS sample rate.It dissipates 0.72 mW with a 3.3 V power supply and occupies dimensions of 0.42×0.68 mm~2.     

直流脉宽调速系统电流脉动规律分析

本文在研究直流脉宽调速系统的电流脉动规律中,推导了PWM变换器处于不同工作状态时电流动态过程的统一表达式;分析了电动机在不同运行状态下的电流波形,给出了电动运行状态和降速过程的转速、电枢电流和电压的响应曲线;得出了无论电动机处于电动还是制动状态,在一个开关周期内,电枢电压在电源电压和零电压间切换,电流动态过程包括电流上升和下降两段,都遵循所推导出的电流表达式。笔者通过仿真,研究了PWM信号的占空比、开关周期和电磁时间常数等参数对电流脉动幅值的影响。     

Proton conduction in the binary system (1 − x)CsHSeO4–xKHSeO4 studied with a free-energy model

Electrical Impedance Spectroscopy (EIS) was used to study the electrical properties of the (1???x)CsHSeO₄–xKHSeO₄ binary system with concentrations x?=?0.0 and 0.1. The results show a higher proton-conduction phase above 80°C for both concentrations, however, while DC conductivity of CsHSeO₄ shows a gradual change to higher values in the 80–118°C temperature range, the 0.9CsHSeO₄–0.1KHSeO₄ concentration reveals an abrupt change at about 80°C to an intermediate temperature phase. The observed behavior for the doped sample was modeled using a trial free-energy density, based on the concentration of mobile ions, that takes into account the formation of defects, configurational and phonon entropies, and defect-defect interactions. By minimising the free-energy density one obtains two roots for the carrier concentration at a given temperature, which corresponds to a stable and metastable configuration. It is possible to characterise the phase behavior of the system by means of temperature and two model parameters, which depend on the crystalline properties of the system, but not on temperature. One can successfully explain the conductivity behavior of the system by changing the model parameters if it is assumed that its variations are due to the carriers density.     

LTE通信基站市电引入设计中应该考虑的问题

LTE通信基站市电引入的设计是基站建设的首要环节,直接关系到基站供电的可靠性和安全性,对通信网络的安全运行起到关键的作用。基站市电引入的设计多数由施工单位自行设计施工,造成基站市电引入方式出现较混乱的局面,不合理的设计施工会造成巨大的经济损失。做好基站市电引入设计,使市电引入方式合理化、简单化,在加大可靠性和安全性的基础上,降低投资成本,减少维护量能保障通信畅通,提高经济效益。     

Microwave‐assisted extraction in combination with HPLC‐UV for quantitative analysis of six bioactive oxoisoaporphine alkaloids in Menispermum dauricum DC

A novel and reliable method based on microwave‐assisted extraction (MAE) followed by HPLC‐UV was developed and validated for the simultaneous quantification of six pharmacologically important oxoisoaporphine alkaloids in the total plants of Menispermum dauricum DC. The optimal MAE extraction condition was performed at 60°C for 11 min with ethanol–water (70:30, v/v) as the extracting solvent, and the solvent to solid ratio was 20:1. Chromatographic separation was achieved on a reversed‐phase YMC C₁₈ column (250 × 4.6 mm, i.d., 5 µm) with a gradient mobile phase consisting of A (1% aqueous formic acid) and B (acetonitrile containing 1% formic acid) at a flow rate of 1.5 mL/min. The detection wavelength was set at 422 nm. Excellent linearity over the investigated concentration ranges was observed with values of r >0.999 for all analytes. The method developed was validated with acceptable sensitivity, intra‐ and inter‐day precision and extraction recoveries. It was successfully applied to the determination of six alkaloids in Menispermum dauricum DC from different sources and different parts of Menispermum dauricum DC. The results obtained indicated that the method is suitable for the quality control of Menispermum dauricum DC. Copyright © 2015 John Wiley & Sons, Ltd.     

Designing nickel phthalocyanine periphery by alkyl chain via [1,3,4]-oxadiazole

Nickel phthalocyanine (NiPc, 1) periphery has been decorated by alkyl chains of varying chain length via [1,3,4]-oxadiazole moiety (NiPcs 3a–3f). All the newly synthesized compounds NiPcs 3a–3d have been completely characterized by elemental analysis, FT-IR, solid-state UV-Vis, and solid-state ¹³C NMR spectroscopy, in addition to X-ray diffraction, scanning electron microscopy, and thermal analysis. The effect of chain length in the NiPc periphery on electronic absorption and DC electrical conductivity has been investigated.     

Synthesis,characterization, corrosion inhibition of mild steel in HCl (0.5 N) solution and solid‐state electrical conductivity of new Co(II), Ni(II), Cu(II) and Zn(II) complexes

This work consists of a study of the corrosion‐inhibiting and semiconducting properties of new binuclear Co(II), Ni(II), Cu(II) and Zn(II) complexes with a Schiff base, H₂L, obtained from the 2:1 M condensation of salicylaldehyde and o‐dianisidine, respectively. Elemental, spectral and thermal analyses were used to characterize these complexes. The magnetic susceptibilities of these complexes were also determined. Weight loss, potentiodynamic polarization and scanning optical microscopy were the techniques used to investigate the efficiency of these new compounds as corrosion inhibitors. The antibacterial activity of the compounds was measured against sulfate‐reducing bacteria. It was found that inhibition occurs via the chemisorption of metal complexes on the steel surface. This absorption obeys the Langmuir adsorption isotherm model.     

DC Electrical Conductivity of the Direct Electrochemically Synthesized Polythiophene Metal Complexes

Electrochemical anodic oxidation of a metal anode in an acetone solution of 2,5-diamino-3,4-dicyanothiophene gave the polythiophene metal complexes of Co, Ni, Cu, Zn, Cd, and Sn. Chemical analyses, as well as FTIR and electronic spectral data, are presented to confirm the formulation of the isolated materials. DC electrical conductivity measurements of the polymer complexes were measured in the range 300–500 K in the annealed and 5% doped forms. The products gave electrical conductivity in the semi-conducting region that increased by heat.     

Compensating the effects of DC bias lines on terahertz photomixer antennas using resistively loaded lines

This paper proposed a method, namely resistively loaded lines (RLL), to compensate the effects of the DC bias lines after investigating its effects on several types of antennas for terahertz photomixers. The RLL is formed by placing lumped resistances periodically on the DC bias line in order to cease the leakage current virtually, which cause a significant amount of distortion on the antenna performance. The simulation results of the dipole, folded dipole, log-periodic, and spiral antennas show that RLL almost removes the effects of the bias lines and improves the antenna radiation resistance and radiation pattern notably compared with that of the commonly used bias line types, such as coplanar stripline and photonic bandgap type bias lines.