纵向抽运准三能级连续激光器的抽运吸收饱和效应

基于速率方程和腔内光传输方程,推导了纵向抽运准三能级连续激光器的抽运吸收效率、斜率效率、腔内基波几何平均光强、激光阈值、激光输出光强和功率的显式解析表达式。讨论了抽运吸收饱和效应对抽运吸收效率、激光阈值、激光转换效率和腔内基波几何平均光强的影响。理论分析和数值模拟表明,抽运饱和效应对激光性能的影响与抽运吸收截面和激光发射截面的比值、平均单程损耗因子、抽运能级与激光上下能级的粒子数布居因子及晶体长度等因素有关。当晶体越短、抽运吸收截面和激光发射截面的比值越大、腔损耗越大时,抽运吸收饱和效应越明显。抽运吸收效率的下降会导致激光阈值升高、腔内基波几何平均光强以及激光转换效率的下降

Controlling Reversible Expansion of Li2O2 Formation and Decomposition by Modifying Electrolyte in Li-O2 Batteries

锂空电池分别使用空气中的氧气和金属锂作为正负极活性材料，具有极高的能量密度。但是，这一体系尚不能实现商业化的应用，其中一些关键问题未能解决。由于其正极活性材料是气体，使得电化学反应涉及气-液-固三相界面，电极过程十分复杂。与其它二次电池相比，空气电极需要考虑结构因素和催化因素。不仅要改善氧气电化学反应的动力学迟缓问题，还要考虑放电产物的驻留空间问题。董全峰教授课题组在前期开展了基于空气电极固相表面电催化研究，并结合电极结构方面的问题，构筑了有利于氧气发生反应的仿生开放式结构电极。 该研究工作主要由化学化工学院2015级iChEM直博生林晓东（第一作者）在董全峰教授、郑明森副教授和龚磊副教授的共同指导下完成，理论计算由袁汝明助理教授（共同第一作者）完成，曹勇、丁晓兵、蔡森荣、韩博闻等学生参与了部分工作。周志有教授和洪宇浩博士生在电化学微分质谱方面给予大力的帮助与支持。【Abstract】The aprotic lithium-oxygen (Li-O2) battery has attracted worldwide attention because of its ultrahigh theoretical energy density. However, its practical application is critically hindered by cathode passivation, large polarization, and severe parasitic reactions. Here, we demonstrate an originally designed Ru(Ⅱ) polypyridyl complex (RuPC) though which the reversible expansion of Li2O2 formation and decomposition can be achieved in Li-O2 batteries. Experimental and theoretical results revealed that the RuPC can not only expand the formation of Li2O2 in electrolyte but also suppress the reactivity of LiO2 intermediate during discharge, thus alleviating the cathode passivation and parasitic reactions significantly. In addition, an initial delithiation pathway can be achieved when charging in turn; thus, the Li2O2 products can be decomposed reversibly with a low overpotential. Consequently, the RuPC-catalyzed Li-O2 batteries exhibited a high discharge capacity, a low charge overpotential, and an ultralong cycle life. This work provides an alternative way of designing the soluble organic catalysts for metal-O2 batteries.This work was supported by the National 973 Program (2015CB251102), the Key Project of National Natural Science Foundation of China (21673196, 21621091, 21703186, 21773192),and the Fundamental Research Funds for the Central Universities (20720150042,20720150043). The authors thank Prof. Eric Meggers at Philipps-Univeristaet Marburg for his discussion about the synthesis of RuPC complex; Prof. Gang Fu at Xiamen University for his instructive discussions in DFT calculations; Lajia Yu and Dandan Tao at Xiamen University for their assistance in EPR experiments and UV-Vis spectroscopy experiments, respectively; and Yu Gu and Tao Wang at Xiamen University for their discussions in XPS results and CV data,respectively. 该工作得到科技部重大基础研究计划（项目批准号：2015CB251102）、国家自然科学基金（项目批准号：21673196、21621091、21703186、21773192）和中央高校基本科研业务费专项资金（项目批准号：20720150042、20720150043）的资助。 此外，感谢傅钢教授在理论计算方面的讨论和建议，Eric Meggers教授在配合物合成上的讨论，泉州师范学院吴启辉教授和化学化工学院谷宇博士生在X射线光电子能谱方面的帮助，于腊佳老师在电子顺磁共振实验上的帮助，陶丹丹博士生在紫外可见光谱测试上的帮助以及王韬博士生在循环伏安方面的讨论

关于“经济发展方式转变进程中的财税政策”的探讨(笔谈)

转变经济发展方式是当前中国的热门话题,而上海在城市发展中又肩负着率先转变的重要任务,在这一意义和背景下,2010年4月24日由上海金融学院学院主办、上海金融学院公共经济管理学院承办的“《中国城市财政发展报告2009/2010:促进‘两个中心’建设的上海城市财政》首发式暨‘经济发展方式转变进程中的财税政策’论坛“在我校举行。与会专家围绕经济发展方式转变进程中的财税政策的“趋势与目标“、“机遇和挑战“、“实施方略“和“地方实践“等四个专题进行研讨,各抒己见,智慧交锋。现将其真知灼见整理摘要与读者分享,以期待更多学者共同关注当前经济发展方式转变进程中的财税政策

未飽和含水層之污染物傳輸模式

垃圾掩埋場因降雨、有機物水解或其他因素常產生大量滲出水，而其通常含有重金屬 、有機化學物質或其他毒性污染物質，當此等污染物藉由滲出水流經未飽和含水層後 ，即污染了地下水源。以往的文獻對於此類地下水污染問題雖曾提出了多種不同的模 式 (主要包括了數值模式及數學解析模式兩大類 )，然而此等模式多極為複雜且針對 某些特定情況而建立，并非完整的探討了地下水污染傳輸行為。本研究乃致力於探討 當污染物隨著滲出水流經未飽和含水層時，污染物在土壤中的傳輸特性，而污染物的 傳輸特性受土壤中孔流速度 (pore water velocity)的影響效應，亦於本研究中考慮 之，以建立較為廣泛之未飽和含水層中地下水污染傳輸模式。本文采用一維垂直水流 方程式及溶質傳輸方程式，輔以適當的初始條件及邊界條件，并以數學解析的方法， 建立污染物在未飽和含水層中的傳輸模式。本研究之解析乃擴展 Philip (1957)提出 的冪級數展開法，分別應用於含重力項之一維水流及溶質傳輸方程式，本模式并探討 延散係數(dispersion coefficient)為土壤中孔流速度或純粹為含水量(water cont- ent)的函數時，污染物於土壤中分佈情況的異同。由本文之結果，土壤中除含水量因 素外，孔流速度及重力效應對污染物之傳輸有顯著之影響。本模式的建立，將有助於 了解和預估地下水源受到的污染程度

Multiple-Candidate Generation and Separation by Turbo Coding

多信號產生技術的原理，就是將相同的使用者資料，利用某種方法產生Q>1種不同的表示信號。傳送端根據不同的傳送需求從中選出一個信號來傳送。一般而言，在傳送端傳送資料時，附帶消息必須隨著被傳送的資料一同被傳出。如此，接收端才能根據所收到的附帶消息，來復原被傳送資料。但這額外傳送的附帶資料將會造成一些資料量的損失，或者是在接收端時解碼時，錯誤的附帶資料將會造成增加系統錯誤率。篇論文中，我們提出兩種具多信號產生特性之渦輪碼。第一類是在渦輪碼的系統下利用不同的交錯器或是隨機序列來產生多個信號。這一類系統的特點是就是傳送端不需要傳送額外的附帶資料，在接收端我們利用渦輪解碼時的判別能力來挑選可能被傳送的資料。一類多信號產生的技術是採用咬合碼的觀念，這想法可以適用於任何有關於咬合碼的編碼中。例如：咬合式迴旋碼，咬合式渦輪碼。利用咬合碼的限制條件，在不需要明確附帶資料的情況下，接收端一樣可以判別出正確的訊號。了驗證所提出的多信號產生與判別的技術，我們提供了三種渦輪碼系統分別是用來降低高峰均值比、信號衰減與傳送功率的應用。在這些實例中我們發現，所提出的這些多信號產生技術，能比現有的技術提供更好的系統效能或是減少的系統資料量的損失。後，我們所提出的信號產生與判別的觀念不只能應用於渦輪碼上，也適用於其他的編碼系統中。The concept of multiple-candidate is implemented by choosing a candidate from Q>1 candidates, that carry the same user data, for actual transmission based on an appropriate criterion. In general, side information (SI) is included in the transmitted symbols such that receiver can recovery the SI and associated candidate. The extra SI would induce rate loss and incorrect SI would degrade the system performance. In this thesis, we propose two multiple-candidate generation methods for turbo coding.irst, the generation of multiple-candidate without SI by using various interleaver or random sequence in turbo coded system is proposed. Using the powerful discriminating capacity of turbo decoding, the SI can be removed and waived into the turbo codeword.nother multiple-candidate generation with inexplicit SI by employing the tail-biting bits of tail-biting (recursive) convolutional codes or turbo codes is also proposed. Using the tail-biting constraint, the decoding could select the correct candidate sent from transmitter without explicit SI.hree turbo coded systems, which respective aim to reduce the peak to average power ration (PAPR), clipping noise, and average transmit power, are constructed to demonstrate the advantage of the proposed multiple-candidate methods. Compared to the conventional methods, these proposed schemes can eliminate the serious degradation in bit-error performance which results from the incorrect recovery of SI at receiver and avoid/alleviate the rate loss.inally, not only the turbo coding, the proposed multiple-candidate generations could also apply to other coded systems.Abstract --- iiist of Tables --- viist of Figures --- vii Introduction for Multiple-Candidate Representation --- 1 1.1 Methods of generating multiple candidates --- 6 1.1.1 Conventional generation method of multiple candidates --- 8 Multiple candidates for PAPR Reduction --- 11 2.1 Introduction --- 11 2.2 Selective-Mapping for PAPR Reduction --- 16 2.3 Selective-Mapping: without Side Information --- 21 2.3.1 Multiple Interleavers --- 22 2.3.2 Multiple Random Sequences --- 25 2.4 Simulation results and Performance Analysis --- 36 2.4.1 PAPR Distribution --- 37 2.4.2 Complexity --- 44 2.4.3 Error Performance Analysis --- 45 2.4.4 long code application --- 56 2.5 Concluding Remarks --- 60 Multiple candidates for Clipping noise Alleviation ---62 3.1 Introduction --- 62 3.2 Selective-Clipping for Clipping noise Alleviation --- 64 3.3 Selective Clipping: with inexplicit Side Information --- 67 3.3.1 Tail-biting Bits of Tail-Biting RSC Codes --- 67 3.3.2 Tail-biting Bits and Some Information Bits of Tail-Biting RSC Codes --- 70 3.3.3 Tail-biting Bits of Tail-Biting Turbo codes --- 71 3.4 Simulation results and Performance Analysis --- 73 3.4.1 Error Performance and Complexity --- 73 3.4.2 Performance Analysis --- 77 3.5 Concluding Remarks --- 79 Multiple candidates for Transmitted Power Minimization --- 81 4.1 Introduction --- 81 4.2 Analysis of the Capacity of average power reduction --- 84 4.2.1 Power distribution of M^2-QAM signal points for Q=1 --- 85 4.2.2 Power distribution of M^2-QAM signal points for Q>1 --- 87 4.3 Multiple-candidate shaping for Turbo coded modulation ----- 92 4.3.1 Shaping for Turbo Trellis-Coded Modulation --- 92 4.3.2 Shaping for Pragmatic Turbo Coded Modulation ---104 4.4 Simulation results and Performance Analysis --- 106 4.5 Concluding Remarks --- 113 Conclusion --- 115ibliography --- 11