Analysis of switched capacitor DC-DC step down converter

A 5V/1 V Switched Capacitor (SC) dc-dc converter designed for a 0.18μm CMOS process is analysed in detail, in this paper. Analytical equations are derived for the voltages and currents through the main components of the SC converter. The model includes switches, capacitors, equivalent series resistances and the load. The switches in the converter are represented by MOSFETs in the UMC 0.18μm CMOS process. The impact of system parameters on output voltage ripple are studied using the analytical expressions.

Directly modulated wavelength-multiplexed integrated microring laser array

The first demonstration of a directly modulated microring laser array is presented for on-off keyed, wavelength- division- multiplexed fiber-optic data transmission. GaInAsP-InP microring resonators oscillating at separate wavelengths in the 1.5-μm band are vertically coupled to a common passive waveguide bus, which is fabricated on the reverse side of the InP membrane. Two microrings defined with radii for a wavelength channel separation of 6 nm have been assessed for both individual and simultaneous operation. Negligible power penalty (<0.2 dB) is observed for wavelength-division-multiplexed operation with and without transmission over a 25-km fiber span in a manner which indicates low crosstalk between the integrated sources. A device area of less than 0.12 mm2 per microring on a common passive bus allows a highly scalable solution for short-reach wavelength-multiplexed links. © 2008 IEEE.

Er3+-doped glass-polymer composite thin films fabricated using combinatorial pulsed laser deposition

Siloxane Polymer exhibits low loss in the 800-1500 nm range which varies between 0.01 and 0.66 dB cm1. It is for such low loss the material is one of the most promising candidates in the application of engineering passive and active optical devices [1, 2]. However, current polymer fabrication techniques do not provide a methodology which allows high structurally solubility of Er3+ ions in siloxane matrix. To address this problem, Yang et al.[3] demonstrated a channel waveguide amplifier with Nd 3+-complex doped polymer, whilst Wong and co-workers[4] employed Yb3+ and Er3+ co-doped polymer hosts for increasing the gain. In some recent research we demonstrated pulsed laser deposition of Er-doped tellurite glass thin films on siloxane polymer coated silica substrates[5]. Here an alternative methodology for multilayer polymer-glass composite thin films using Er3+ - Yb3+ co-doped phosphate modified tellurite (PT) glass and siloxane polymer is proposed by adopting combinatorial pulsed laser deposition (PLD). © 2011 IEEE.

3.0～2.0Ma B. P.南海南部深海沉积物孢粉记录及其对全球变化的响应

为了重建东亚季风区域2.5MaB.P.前后植被和气候变化的历史，更好地了解低纬度地区植被变化及其对全球变化的响应，本研究选择了南海南部ODP1143站深海沉积物中的孢粉样品进行研究。通过高分辨率（7ka）的孢粉样品的分析研究，建立起3.0～2.0MaB.P.时段南海深海沉积孢粉组合序列，系统建立了这一时段植被演替序列。在此基础上，重点研究了2.5MaB.P.前后气候变化在南海周边地区植被演替中的响应，为探索和揭示东亚古季风及古环境演变提供了孢粉学依据。 ODP 1143站位于南沙海区，北纬9º22´，东经113º17´，深海柱状样采于水深2772m的大陆坡。本研究以生物地层学和氧同位素年代学为依据建立了年龄框架，对1143站135～95m（3.0～2.6 Ma B. P.）深海沉积中的孢粉样品进行了分析，建立了3.0～2.0MaB.P.时段南海深海沉积孢粉组合序列。孢粉样品处理方法主要是用盐酸去掉钙质和氢氟酸浸泡溶解硅质后，再用筛子将样品在超声波发生器中震荡过滤。孢粉的鉴定和统计在光学透视显微镜下完成。研究结果表明： 1、孢粉谱的主要特征是沉积率变化显著。与3.0～2.6 Ma B. P. 相比，2.6～2.0 Ma B. P.各类型花粉及孢子沉积率均有显著提高。该结果表明2.6 Ma B. P.南海海平面有显著下降，可与北半球冰盖形成、东亚季风增强相对应。 2、2.6 Ma B. P.以来，各类型孢粉沉积率变化与深海氧同位素分期相对应，代表了多次冰期-间冰期旋回。该结果表明南海海平面曾有多次上升和下降。 3、频谱分析结果表明，3.0～2.0 Ma B. P.存在0.1 Ma（偏心率）和46.9ka（斜率）的周期。

Sampling design tool for ArcGIS: Instruction manual.[for ESRI ArcGIS 10.0 Service Pack 3 or higher]

The Biogeography Branch’s Sampling Design Tool for ArcGIS provides a means to effectively develop sampling strategies in a geographic information system (GIS) environment. The tool was produced as part of an iterative process of sampling design development, whereby existing data informs new design decisions. The objective of this process, and hence a product of this tool, is an optimal sampling design which can be used to achieve accurate, highprecision estimates of population metrics at a minimum of cost. Although NOAA’s Biogeography Branch focuses on marine habitats and some examples reflects this, the tool can be used to sample any type of population defined in space, be it coral reefs or corn fields.

生态系统服务功能价值评估—以锡林河流域天然草地生态系统为例

时空尺度和生态系统的健康状况是影响生态系统服务功能的重要因素。锡林河流域天然草地关键的地理位置和独特的生境条件使其具有十分重要的生态意义和经济价值。评估锡林河流域天然草地在不同时空尺度及生态系统健康状况的生态系统服务功能的价值，不仅能够全面客观的评价该流域天然草地的生态服务功能，而且还能够为当地经济政策的制定，经济的建设发展提供科学依据。 本研究以锡林河流域天然草地为例，通过对草地生态系统服务功能价值评估和计算机情景模拟，研究了不同空间尺度及放牧影响锡林河流域天然草地生态系统服务功能价值。对于不同空间尺度下草地生态系统服务价值的研究，根据草地的产草量和退化程度将锡林河流域天然草地划分成5个级别，利用Costanza等的基本思路和方法，进行了价值评估。结果表明锡林河流域草地生态系统每年的服务价值为76.154×108元。受各级草场的生产量和放牧强度的综合影响，健康程度不同的各等级天然草地的单位面积生态系统服务功能的价值存在着很大差异，从1级草地到5级草地，单位面积服务价值比重从38.1%下降到4.8%。参考国际、国内和锡林浩特当地三种不同的生态系统服务单价，计算得出这三种不同空间尺度下锡林河流域天然草场生态系统服务价值分别为：88.199×108元/年、76.154×108元/年、14.236×108元/年，并且各项服务功能在总价值中所占的比例也随空间尺度变化。以气体调节为例，服务价值的比重分别占3.7%、11.0%和7.9%，这说明生态系统服务功能的价值与空间尺度有关。 通过草地生态系统服务功能当量因子得到不同类型草地生态系统单位面积服务价值，研究放牧影响下各类型草地生态系统单位面积服务价值以及年平均累积服务价值。草地生态系统服务功能当量因子说明生态系统各项服务功能不仅与生态系统的生物量有关，同时受到生态系统内环境因子、生物因子、生态系统过程多方面因素的共同作用。最大直接经济价值放牧率大于生态系统服务功能最大时的放牧率，但是获得经济利润小于生态系统服务功能最大时的价值。同时，在各类草地生态系统中单位面积服务价值以贝加尔针茅草原最高为2242.347元/公顷，克氏针茅草原最低为1655.413元/公顷。草地生态系统的累积服务价值在时间范围一定时随放牧率变化明显，并且时间范围越大变化越大。重牧状态下的草地生态系统累积服务价值最低，且随时间的增加而减少;无牧、轻牧和中牧状态下草地生态系统的累积服务价值则随时间的延续而增长。以上结果说明放牧对草地生态系统服务功能有显著影响，以经济利益为目的获得最大利润的放牧方式带来的经济价值是短期的，从长远看，只有科学管理，合理放牧，才能使草地生态系统长期稳定的提供最佳的生态系统服务功能。