LINEAR ISOSTATIC GRAVITY ANOMALIES IN THE SOUTH CHINA SEA

In this paper a model of linear isostatic gravity has been shown in the South China Sea. By means of resolving a stochastic integral equation, a compensating density, which is corresponding to the topographic masses of unit volume, has been established. By calculation, the average depth of the mantle bottom under the South China Sea is 450 km and the depth of one of the interfaces within the layer B is 250 km. The depression areas of the South China Sea are caused by the surplus of the compensation in the depth between 450 and 560 km. The compensating and isostatic gravity anomalies have been resolved, and a geological interpretation has been made.     

AlN晶体物理气相传输法生长坩埚的热场分析

采用物理气相传输法在钨制坩埚上制备AlN单晶.通过采用COMSOL软件中的固体传热和磁场模块,对AlN晶体生长的坩埚的热场进行仿真,同时针对不同的线圈直径以及不同的线圈位置对坩埚热场的影响进行模拟,提出了相应的处理方式.结果表明:当线圈直径增大,坩埚结晶区和升华区的温度在相同的加热时间下会增加,并且增加的温度存在峰值.当线圈的垂直位置发生变化的时候,结晶区和升华区的温度场也会发生变化,从上向下移动的过程中仍然存在温度的峰值,并且结晶区和升华区的温度关系会发生翻转,导致温度梯度阻碍晶体生长.在晶体生长过程中升华区和结晶区的温度关系依旧会发生翻转.但是通过线圈跟随籽晶表面生长层的变厚而同步移动,可以保持相对稳定的温度关系,维持晶体正常持续生长.     

5-HIAA在MWNT-Nafion修饰电极上的伏安行为

研究了在磷酸盐缓冲溶液(pH 7.0)中,5-羟基吲哚乙酸(5-HIAA)在MWNT-Nafion修饰电极上的电化学行为.5-HIAA在MWNT-Nafion修饰电极上出现一个灵敏的氧化峰.与裸玻碳电极相比,MWNT-Nafion修饰电极提高5-HIAA的氧化峰电流.优化了各项测定参数,建立了一种直接测定HIAA的电分析方法.富集电位为-0.5 V,富集时间为300 s,氧化峰电流与5-HIAA的浓度在9.95×10-5～7.98×10-3 mol/L之间有良好的线性关系,检出限为2.5×10-6 mol/L.     

成都市城市绿地土壤理化性质研究

对成都市绿地土壤的理化性质进行了研究,并与郊区的土壤作了比较.结果显示,该市绿地土壤的pH明显高于市郊,而有机质含量和总硫含量则低于市郊.     

关于线性方程组的一个注记

本文证明了方程组（In＋AB）x=0和（In＋BA）x=0解的个数是一致的。     

杭州市2017年冬季一次重灰霾过程中PM2.5水溶性离子特征、来源及成因分析

利用在线监测仪测量了杭州市一次重灰霾过程（2017年12月29日至2018年1月3日）中PM_2.5主要水溶性离子（Cl^-、SO₄^2-、NO₃^-、NH₄⁺、Na⁺、Ga²⁺、Mg²⁺）及主要气态污染物（SO₂、NO₂、O₃、NO、CO、HCl、NH₃、HNO₂、HNO₃）的小时浓度。结合混合受体模型和国控监测分析,研究了2017年12月30-31日重灰霾事件的污染特征、来源和成因。研究结果表明：PM_2.5浓度高达318 μg·m^-3; NO₃^-/SO₄^2-最大值为2.68,说明移动源污染是杭州市PM_2.5形成的重要来源; PM_2.5/CO最高达到0.19,说明二次细颗粒物对PM_2.5贡献很大;NO₃^-、SO₄^2-、NH₄⁺的浓度总和占PM_2.5平均浓度的64.3%,说明二次无机细颗粒物是杭州重灰霾形成的重要原因,且NO₃^-的贡献最大,占33.5%。混合受体模型分析显示,杭州市重灰霾污染的潜在源区主要位于安徽、江苏、河南、山东四省交界处,以及安徽省中东部、蚌埠、芜湖等工业污染较为严重的城市。夹杂着大量污染物的北方干冷空气远距离传输叠加部分局地源是杭州此次重雾霾形成的根本原因。因此,为了改善杭州市空气质量,不仅需控制当地的污染物排放,而且还需对整个长三角地区甚至跨区域采取大气联防联控策略。     

All-optical format conversion of NRZ-OOK to QPSK and 16QAM signals via XPM in a SOA-MZI

This letter proposes a scheme for the format conversion of on-off keying (OOK) signal to quadrature phase-shift keying (QPSK) and 16-ary quadrature amplitude modulation (16QAM) signals via cross-phase modulation (XPM) in a semiconductor optical amplifier (SOA). Theoretical and experimental analyses of the format conversion scheme are conducted to validate its feasibility. The phase changing is obtained because of the XPM in the SOA. The QPSK and 16QAM signals are converted from the OOK signal. The performance of the 10 Gb/s format conversion system is evaluated and discussed. The receiver sensitivities of the converted QPSK and 16QAM signals after detection are -27.25 and -23.5 dBm, respectively, at a bit error rate (BER) of 109 .     

Remotely pumped EDFA-based 40-Gb/s downstream and 10-Gb/s upstream long-reach WDM PON employing RSOA and FBG equalizer

We propose a remotely pumped Er-doped fiber amplifier （EDFA）-based 40-Gb/s downstream and 10- Gb/s upstream transmission long-reach wavelength division multiplexing passive optical network （WDM- PON） scheme with downstream and upstream transmission implemented by quadrature phase-shift keying （QPSK） transceiver and reflective semiconductor optical amplifier （RSOA）-based intensity modulation direct detection （IM-DD）. Transmissions of the 40-Gb/s QPSK downstream, using a Mach-Zehnder mod- ulator, and the 10-Gb/s non-return-to-zero on-off keying （NRZ-OOK） upstream, using a 1.2-GHz RSOA equalized by fiber Bragg grating （FBG）, are demonstrated with 40-km fiber transmission.     

Improving the performance of a GaAs nanowire photodetector using surface plasmon polaritons

GaAs nanowires (NWs) are ideal materials for preparing near-infrared photodetectors owing to their high charge carrier mobility and direct band gap. Although the performance of GaAs NW photodetectors can be enhanced by surface passivation or doping, it still cannot meet the requirement for applications. In this paper we propose a method to greatly improve the performances of GaAs NW photodetectors by hot-hole injection via surface plasmon polaritons. In this case, the responsivity of a single GaAs NW photodetector is increased by a fact of 3.2 to 6.56 A· W^-1 by attaching capsule-like Au nanoparticles to its surface. This research uses an efficient route to improve the NW photocurrent, which is also important for the development of a high-performance near-infrared NW photodetecor.     

Experimental and theoretical analyses of RSOA-based colorless-ONUs with 4PAM signal in the up-link

A scheme that utilizes the 4-level pulse-amplitude-modulated (4PAM) signal as the re-modulated signal of colorless optical network units (ONUs) based on reflection semiconductor optical amplifiers (RSOAs) is proposed. The system with 10-Gb/s non-return-to-zero (NRZ) downstream and 5-Gb/s 4PAM upstream signals is theoretically analyzed and experimentally verified. Simulation and experimental results reveal that the 4PAM re-modulated signal yields better performance than the NRZ signal in the upstream. A receiver power penalty of 1.6 dB is also improved by the 4PAM signal at back-to-back (BtB) transmission, whereas another receiver power penalty of 1.5 dB improved after 30-km single mode fiber transmission, where 4PAM signals are used as upstream signal.