Design of constant voltage and constant current switching power supply

随着电子科技日新月异的发展，每家每户使用的电器设备越来越多，而电器设备往往需要合适的电源来驱动。特别是带有锂电池的离线设备，比如吸尘器、电动车、手机、数码相机等需要高精度的恒压恒流的充电器，使之合理的充电曲线保证锂电池的充电安全和寿命。 开关电源因其小体积、低功耗、高可靠性、高效率等诸多优点受到广泛的关注。开关电源是通过PWM信号控制MOS器件开和关，使输入连续的直流电变成间断的脉冲，再通过电容电感储能滤波，将间断的脉冲滤成连续的直流电。从而可知，只要调节MOS器件的开、关时间比就可以改变输出电压和输出电流的数值，同时输出电压或者电流的数值变化会被负反馈到控制MOS管开关动作时间比，从而控制...With the rapid development of Electronic Science and technology, more and more appliances and equipment used in each household, and electrical equipment often need the right power to drive. Especially the offline device with a lithium battery, such as vacuum cleaners, electric cars, mobile phone, digital camera need high precision constant current constant voltage charger, the reasonable charging ...学位：工程硕士院系专业：信息科学与技术学院_工程硕士(电子与通信工程)学号：X201222201

中国海及邻近区域碳库与通量综合分析

中国海总面积约470万平方公里,纵跨热带、亚热带、温带、北温带等多个气候带.其中,南海北依\"世界第三极\"青藏高原、南邻\"全球气候引擎\"西太平洋暖池,东海拥有全球最宽的陆架之一,跨陆架物质运输显著,黄海是冷暖流交汇区域,渤海则是受人类活动高度影响的内湾浅海.中国海内有长江、黄河、珠江等大河输入,外邻全球两大西边界流之一的黑潮.这些鲜明的特色赋予了中国海碳储库和通量研究的典型代表意义.文章从不同海区（渤海、黄海、东海、南海）、不同界面（陆-海、海-气、水柱-沉积物、边缘海-大洋等）,以及不同生态系统（红树林、盐沼湿地、海草床、海藻养殖、珊瑚礁、水柱生态系统等）多层面对海洋碳库与通量进行了较系统地综合分析,初步估算了各个碳库的储量与不同碳库间的通量.就海气通量而言,渤海向大气中释放CO2约0.22Tg Ca-1,黄海吸收CO2约1.15Tg Ca-1,东海吸收CO2约6.92～23.30Tg Ca-1,南海释放CO2约13.86～33.60Tg Ca-1.如果仅考虑海-气界面的CO2交换,中国海总体上是大气CO2的\"源\",净释放量约6.01～9.33Tg Ca-1.这主要是由于河流输入以及邻近大洋输入所致.河流输入渤黄海、东海、南海的溶解无机碳（DIC）分别为5.04、14.60和40.14Tg Ca-1,而邻近大洋输入DIC更是高达144.81Tg Ca-1,远超中国海向大气释放的碳量.渤海、黄海、东海、南海的沉积有机碳通量分别为2.00、3.60、7.40、7.49Tg Ca-1.东海和南海向邻近大洋输送有机碳通量分别为15.25～36.70和43.39Tg Ca-1.就生态系统而言,中国沿海红树林、盐沼湿地、海草床有机碳埋藏通量为0.36Tg Ca-1,海草床溶解有机碳（DOC）输出通量为0.59Tg Ca-1;中国近海海藻养殖移出碳通量0.68Tg Ca-1,沉积和DOC释放通量分别为0.14和0.82Tg Ca-1.总计,中国海有机碳年输出通量为81.72～103.17Tg Ca-1.中国海的有机碳输出以DOC形式为主,东海向邻近大洋输出的DOC通量约15.00～35.00Tg Ca-1,南海输出约31.39Tg Ca-1.综上,尽管从海-气通量看中国海是大气CO2的\"源\",但考虑了河流、大洋输入、沉积输出以及微型生物碳泵（DOC转化输出）作用后,中国海是重要的储碳区.需要指出的是,文章数据是基于中国海各海区碳循环研究报道,鉴于不同研究方法上的差异,所得数据难免有一定的误差范围,亟待将来统一方法标准下的更多深入研究和分析.国家重点研发计划项目(编号:2016YFA0601400);;国家自然科学基金项目(批准号:91751207、91428308、41722603、41606153、41422603);;中央高校基础研究项目(编号:20720170107);;中海油项目(编号:CNOOC-KJ125FZDXM00TJ001-2014、CNOOCKJ125FZDXM00ZJ001-2014)资

Seismic exploration at Fuji volcano with active sources : The outline of the experiment and the arrival time data

Fuji volcano (altitude 3,776m) is the largest basaltic stratovolcano in Japan. In late August and early September 2003, seismic exploration was conducted around Fuji volcano by the detonation of 500 kg charges of dynamite to investigate the seismic structure of that area. Seismographs with an eigenfrequency of 2 Hz were used for observation, positioned along a WSW-ENE line passing through the summit of the mountain. A total of 469 seismic stations were installed at intervals of 250-500 m. The data were stored in memory on-site using data loggers. The sampling interval was 4 ms. Charges were detonated at 5 points, one at each end of the observation line and 3 along its length. The first arrival times and the later-phase arrival times at each station for each detonation were recorded as data. P-wave velocities in the surface layer were estimated from the travel time curves near the explosion points, with results of 2.5 km/s obtained for the vicinity of Fuji volcano and 4.0 km5/s elsewhere

The Hydraulic Characteristics of the Revegetation Holes of the Safety Ecological Revetment

In order to apply the vegetation bags and make green on the reinforced concrete revetment, the diameter of the drainage holes is enlarged to thirty centimeters. The modified reinforced concrete revetment not only maintain safety but also beautify the appearance. For the sake of effectuation in worksite, this research chooses experimental revetment model to discuss, the characteristics of flow velocity and discharge within revegetation holes. In addition, this study discussed the hydraulic characteristics under the combinations of two types of refilled sediment, four revegetation holes with different slopes, and the relationship of drawdown with time series. In summary, there are some results concerning this study. They are presented as follows: 1. The refilled sediment was the main factor. In similar slope, both the velocity and the discharge of the refilled with the uniformity coefficient 10.45 sediment are bigger than the uniformity coefficient 19.92 sediment. 2. In the same refilled sediment, when the slope of revegetation hole is increased, both the velocity and the discharge are lesser. 3. In similar slope, the drawdown with time series of the filled with the uniformity coefficient 19.92 sediment is longer than the uniformity coefficient 10.45 sediment. 4. In the same refilled sediment, when the slope of revegetation hole is increased, the drawdown with time series is longer.為改善現有之鋼筋混凝土護岸，將排水孔直徑加大至30公分，使之能填充植生包植生綠化護岸，此能較符合生態之原則，且鋼筋混凝土之結構也具安全性，護岸的外觀亦可砌石加以美化。本文採用試驗護岸模型以探討栽植孔之排水流量及流速等現象。 本試驗針對生態護岸模型所設置的栽植孔進行試驗，以二種不同均勻係數之回填砂石(10.45及19.92)、四種不同斜率之洩水管(-8°、0°、4°及8°)以及水位洩降與時間之關係進行探討。 由試驗結果可以得到： 1.回填砂石粒徑為影響排水孔流速及流量之最主要因素。於相同洩水管坡度的情況下，回填均勻係數10.45之試驗砂石時所量得的流速及流量皆大於回填均勻係數19.92試驗砂石時之值。 2.於相同回填砂石粒徑情況下，洩水管愈向上傾斜，流速及流量亦愈小。 3.於相同洩水管坡度的情況下，回填均勻係數19.92之試驗砂石時，水位洩降所需時間較回填均勻係數10.45之試驗砂石長。 4.於相同回填砂石粒徑情況下，洩水管愈向上傾斜，水位洩降所需時間愈長。第一章 緒論 1.1 前言.........................................1 1.2 研究動機.....................................2 第二章 資料收集與整理 2.1 現有護岸的型式...............................4 2.2 護岸種類與適用情形...........................8 第三章 文獻回顧 3.1 排水孔......................................12 3.2 護岸........................................13 3.3 河溪適生植物................................14 第四章 試驗介紹 4.1 試驗介紹....................................16 4.2 試驗目的....................................16 4.3 試驗設備....................................17 4.4 試驗設計及假設條件..........................29 4.5 試驗步驟流程................................30 4.6 模型相似律..................................32 第五章 結果與討論 5.1 各栽植孔於不同狀況下之流速變化情形..........35 5.2 各栽植孔於不同狀況下之流量變化情形..........38 5.3 各栽植孔於不同狀況下之時間與水位洩降關係....41 5.4 由實驗數據進行現況推估......................44 第六章、結論與建議 6.1 結論........................................45 6.2 建議 ........................................47 參考文獻.........................................50 附表.............................................5

合金硬面層及其銲覆用料

一種合金硬面層及其銲覆用料，至少包含有銀材料、鉻材料與碳材料，且以銲覆技術熔接在以鐵材料為主的一基材的一表面。藉此，本發明是在含高鉻與高碳的銲覆用料中加入少量的銀，形成高硬度與高抗磨耗能力的合金硬面層，不但能夠大幅地降低該合金硬面層中單位面積的裂縫長度，且硬度值介於洛氏硬度46到63之間，可有效提升該合金硬面層的性質