摘要：This paper presents the design and experimental results of a continuous-time (CT) sigma-delta (ΣΔ) modulator with data-weighted average (DWA) technology for WiMAX applications. The proposed modulator comprises a third-order active RC loop filter, internal quantizer operating at 160 MHz and three DAC circuits. A multi-bit quantizer is used to increase resolution and multi-bit non-return-to-zero (NRZ) DACs are adopted to reduce clock jitter sensitivity. The NRZ DAC circuits with quantizer excess loop delay compensation are set to be half the sampling period of the quantizer for increasing modulator stability. A dynamic element matching (DEM) technique is applied to multi-bit ΣΔ modulators to improve the nonlinearity of the internal DAC. This approach translates the harmonic distortion components of a nonideal DAC in the feedback loop of a ΣΔ modulator to high-frequency components. Capacitor tuning is utilized to overcome loop coefficient shifts due to process variations. The DWA technique is used for reducing DAC noise due to component mismatches. The prototype is implemented in TSMC 0.18 um CMOS process. Experimental results show that the ΣΔ modulator achieves 54-dB dynamic range, 51-dB SNR, and 48-dB SNDR over a 10-MHz signal bandwidth with an oversampling ratio (OSR) of 8, while dissipating 19.8 mW from a 1.2-V supply. Including pads, the chip area is 1.156 mm2.

摘要：国债市场是一个国家证券市场的重要组成部分,是政府财政政策和货币政策的重要结合点。新中国成立70年来,我国国债市场经历了一个曲折过程。回顾我国国债市场在不同历史发展阶段的特征,系统梳理其发展脉络,概括70年国债市场发展的成就与经验,分析现阶段国债市场发展存在的突出问题,在此基础上,从加快建立统一国债市场步伐、提高国债市场管理的透明度、积极开展国债资金使用绩效评价工作、充分发挥国债市场调控功能、建立健全国债法律制度等方面,对未来我国国债市场发展的前景和重点做了展望。

摘要：We present two designs for a waveguide Oe-quantum-well electro-absorption modulator. In our designs, the strip SOI waveguides are butt-coupled and evanescent-coupled to the modulator, respectively. The proposed Gequantum-weB electro-absorption modulator is based on quantum-confined Stark effect （QCSE）, having a 3-dB bandwidth above 50GHz, as well as a low switching power （around 60fJ/bit at 1435nm）. In the butt-coupled design, the optimized extinction ratio is up to 11.4 dB, while the insertion loss is only 6. 74 dB. For the second one, which utilizes evanescent coupling, the extinction ratio and insertion loss are 9.18 dB and 6. 72 dB, respectively.

摘要：This study investigated the relationship between a subject’s evaluation of injection molding machines (IMMs) and formal design features using Kansei engineering. This investigation used 12 word pairs to evaluate the IMM configurations and employed the semantic differential method to explore the perception of 60 interviewees of 12 examples. The relationship between product feature design and corresponding words was derived by multiple regression analysis. Factor analysis reveals that the 12 examples can be categorized as two styles—advanced style and succinct style. For the advanced style, an IMM should use a rectangular form for the clamping-unit cover and a full-cover for the injection-unit. For the succinct style, the IMM configuration should use a beveled form for the safety cover and a vertical rectangular form for the clamping-unit cover. Quantitative data and suggested guidelines for the relationship between design features and interviewee evaluations are useful to product designers when formulating design strategies.

摘要：详细地阐述了高频大功率SiGe/Si异质结双极晶体管(HBT)设计中的一些主要问题,主要包括器件的纵向设计中发射区、基区以及收集区中掺杂浓度、形貌分布、层厚的选择以及横向布局设计中的条宽、间隔的选择等。并对这些主要参数的选择给出了一些实用的建议。

摘要：Background There is a relatively high failure rate of the femoral component in patients with avascular necrosis at the intermediate-term follow-up. Improving the geometrical fit of the femoral stem against the medullary canal may help to provide long-term survivorship of the hip replacement for patients with avascular necrosis. Methods We designed a specific stem, based on morphometric studies of proximal femoral canals in Chinese avascular necrosis patients and evaluated the stem by finite element analyses, comparing the novel stem with two commercially available and commonly used stems. Results The morphometric data from avascular necrosis patients showed specific geometric differences in the proximal femoral canal, including profile curves in both the sagittal and coronary planes than the patients with femoral neck fracture. The shorter stemmed prostheses （FitmoreR and our stem） performed better than the longer stemmed prosthesis （VerSysR）. Conclusions This is the first study to investigate the femoral geometries of Chinese avascular necrosis patients. Our stem provides better stability and is theoretically beneficial to bone ingrowth, which may increase the long-term stability and fixation of the implant.

摘要：High interfacial energy Li^(0)-electrolyte interface contributes to larger Li^(0) nucleation embryos and a more stable interface,so the interfacial energy is essential for highly reversible Li^(0) deposition/***,a high interfacial-energy artificial solid electrolyte interphase(SEI)with rich LiF embedded in lithiated poly-2-acrylamido-2-methylpropane sulfonic acid(PAMPS-Li)network is designed to realize favorable Li^(0) nucleation and rapid desolvation of Li+*** Li-F bonds in LiF(001)exhibit stronger ion-dipole interactions with Li atoms,offering higher interfacial *** the growth surface energy and total interfacial energy of Li^(0) are balanced,the high interfacial energy SEI with abundant LiF can promote the formation of larger Li^(0) nucleation *** addition,the PAMPS-Li with immobilized anions presents weaker interaction with Li^(0) and possesses higher polymer-Li interfacial energy,and its amide and sulfonic acid groups exhibit higher binding energies with Li^(+).Therefore,PAMPS-Li can easily promote the Li+to escape from the solvent sheath and weaken the desolvation energy *** highly reversible Li^(0) deposition behavior with restricted side reactions is achieved based on the synergistic modification of high interfacial energy SEI with *** importantly,lifespan of multi-layered Li^(0) pouch cell(330 Wh kg-1)with a low N/P ratio(1.67)is over 100 cycles,verifying its potential practical application.

摘要：硅锗异质结双极晶体管(SiGeHBT)一般以重掺硼(B)的应变SiGe层作为基区.精确表征SiGe材料能带结构对SiGeHBT的设计具有重要的意义.在应变SiGe材料中,B的重掺杂一方面会因为重掺杂效应使带隙收缩,另一方面,B的引入还会部分补偿Ge引起的应变,从而改变应变引起的带隙变化.在重掺B的应变SiGe能带结构研究中,采用半经验方法,考虑了B的应变补偿作用对能带的影响,对Jain-Roulston模型进行修正,并分析了重掺杂引起的带隙收缩在导带和价带的分布.

摘要：针对履带式甘蔗收获机在横向斜坡的丘陵山地作业时容易侧翻问题,设计了一种适用于履带式甘蔗收获机的底盘调平机构。基于履带式甘蔗收获机中间有甘蔗输送通道的特点,提出了两侧设置调平机构的方案。开展了底盘调平机构关键部件参数设计和各调整油缸受力分析。根据相似性原理搭建缩小比例的试验平台,对试验平台进行了横向倾翻分析和横向姿态调整试验。理论计算和试验结果表明,横向调整后横向倾翻角比调整前横向倾翻角大,横向倾翻角得到提升,调平底盘可以有效改变整机质心,在一定程度上提升了整机横向稳定性。横向倾翻试验中,调整前横向倾翻角为24.31°,横向调整后横向倾翻角为27.52°,横向调整后横向倾翻角提高13.20%。横向姿态调整试验结果表明,横向调整角最大10°,调整时间为1 s,调整精度在0.5°以内,验证了机构横向姿态调整的可行性。在底盘调平机构初始状态,调整油缸所受负载最大值为871.61 N,换算成样机所需推力为55783.04 N。

摘要：详细论述Si/SiGe量子级联激光器的工作原理,通过对比找到一组合适的Si,Ge和SiGe合金的能带参数,进而应用6×6k.p方法计算了不同阱宽、不同Ge组分Si/Si1-xGex/Si量子阱价带量子化的空穴能级本征值及其色散关系,分析Si/Si1-xGex/Si量子阱空穴态能级间距随阱宽和组分的变化规律,最后应用计算结果讨论了Si/SiGe量子级联激光器有源区的能带设计,有益于优化Si/SiGe量子级联激光器结构.