基于DSP的SVPWM实现方法研究

叙述了空间电压矢量(SVPWM)的基本原理,介绍了采用矩阵求解两相邻向量作用时间的方法和用数字信号处理器TMS320F240生成对称空间电压矢量的方法,它的优异性能可以实时完成SVPWM的控制算法,且速度快、精度高.     

离子交换树脂床层流态化特性研究

对离子交换树脂床层的流态化特性进行了试验研究。根据试验结果，给出了离子交换树脂床层流态化速度计算公式。     

新颖双框架角振动微机械陀螺的制作

介绍了新颖双框架角振动微机械陀螺的工作原理、结构特点、制备工艺及关键工艺的实验结果     

新型除氧剂异抗坏血酸钠的催化动力学分析

锅炉给水除氧剂含量的多少直接影响除氧效果的好坏，为此需及时准确地测定给水中除氧剂的含量。对于异抗坏血酸钠（ＮａＥｒＡ）这种新型除氧剂，采用催化动力学分析方法进行测定．操作简便、快速，准确度高，可测至５μｇ／Ｌ。     

Superior Carrier Lifetimes Exceeding 6 µs in Polycrystalline Halide Perovskites

Lead halide perovskite films have witnessed rapid progress in optoelectronic devices, whereas polycrystalline heterogeneities and serious native defects in films are still responsible for undesired recombination pathways, causing insufficient utilization of photon-generated charge carriers. Here, radiation-enhanced polycrystalline perovskite films with ultralong carrier lifetimes exceeding 6 μs and single-crystal-like electron–hole diffusion lengths of more than 5 μm are achieved. Prolongation of charge-carrier activities is attributed to the electronic structure regulation and the defect elimination at crystal boundaries in the perovskite with the introduction of phenylmethylammonium iodide. The introduced electron-rich anchor molecules around the host crystals prefer to fill the halide/organic vacancies at the boundaries, rather than form low-dimensional phases or be inserted into the original lattice. The weakening of the electron-phonon coupling and the excitonic features of the photogenerated carriers in the optimized films, which together contribute to the enhancement of carrier separation and transportation, are further confirmed. Finally the resultant perovskite films in fully operating solar cells with champion efficiency of 23.32% are validated and a minimum voltage deficit of 0.39 V is realized.     

500 Hz ultraviolet dye laser with pulse energy 1.7 mJ and potential for PLIF imaging

ABSTRACT

This paper describes a high-pulse-energy frequency-doubled ultraviolet dye laser operating at a repetition rate of 500?Hz. The pump source is a laser-diode side-pumped Q-switched Nd:YAG laser with a pulse energy of 29?mJ at 532?nm. A master oscillator power amplifier is employed to amplify the output pulse of the dye laser to 8.1?mJ at 566?nm, and by frequency doubling with BBO crystal a pulse energy of 1.7?mJ at 283?nm is achieved with a pulse width of 8?ns. This is more than four times the largest reported pulse energies generated by other fixed-frequency dye lasers when operating at repetition rates of more than 1?kHz. The conversion efficiency and stability of dye laser are discussed, which show the potential for high-speed laser diagnostics in the fields of combustion and turbulent flow detection.     

Approximation algorithm for constructing data aggregation trees for wireless sensor networks

This paper considers the problem of constructing data aggregation trees in wireless sensor networks (WSNs) for a group of sensor nodes to send collected information to a single sink node. The data aggregation tree contains the sink node, all the source nodes, and some other non-source nodes. Our goal of constructing such a data aggregation tree is to minimize the number of non-source nodes to be included in the tree so as to save energies. We prove that the data aggregation tree problem is NP-hard and then propose an approximation algorithm with a performance ratio of four and a greedy algorithm. We also give a distributed version of the approximation algorithm. Extensive simulations are performed to study the performance of the proposed algorithms. The results show that the proposed algorithms can find a tree of a good approximation to the optimal tree and has a high degree of scalability.     

Adjacent relations of primary phase fields and invariant reactions of the system CaO-SiO2-Nb2O5-La2O3

The adjacent relation of primary phase fields and corresponding invariant reactions of the system CaO-SiO₂-Nb₂O₅-La₂O₃ are of great importance for the study on its phase diagram. In the present work, the phase equilibrium in the high w(La₂O₃) region of CaO-SiO₂-Nb₂O₅-La₂O₃ system was studied by thermodynamic equilibrium experiment. The adjacent relation of primary phase fields was determined and represented in the form of adjacent tetrahedrons. The Alkemade Rule applicable to quaternary phase diagram was deduced, which can be used to infer the liquidus temperature trend on univariant curves. The rule was then used to determine the possible temperature range of invariant reactions corresponding to the adjacent tetrahedron in CaO-SiO₂-Nb₂O₅-La₂O₃ system, and the result was shown in the form of Schairer diagram. Finally, the reaction types of five invariant points were determined according to the Lever Rule for quaternary phase diagram, including: ① L₁+CaO·3SiO₂·2La₂O₃→CaO·SiO₂+SiO₂+La₂O₃·Nb₂O₅, ② L₂→CaO·SiO₂+La₂O₃·Nb₂O₅+SiO₂+CaO·Nb₂O₅, ③ L₃+CaO·3SiO₂·2La₂O₃+2CaO·Nb₂O₅→10CaO·6SiO₂·Nb₂O₅+La₂O₃·Nb₂O₅, ④ L₄+10CaO·6SiO₂·Nb₂O₅→CaO·SiO₂+2CaO·Nb₂O₅+La₂O₃·Nb₂O₅, ⑤ L₅+2CaO·Nb₂O₅→CaO·Nb₂O₅+La₂O₃·Nb₂O₅+CaO·SiO₂.     

RSView32和MATLAB之间的通讯

MATLAB是一种具有强大的矩阵处理功能和绘图功能的应用软件。在许多复杂工程应用中，需要将MATLAB和其他软件交互协同工作。本文介绍了MATLAB与罗克韦尔公司的RSView32的特点，并重点论述了他们之间的通讯方法。     

计量供热系统动态控制理论初探

实现计量供热的两个目标--节能和供热的高质量,需要改变传统供热系统的设计计算方法与调控方法,本文在分析计量供热系统的特性的基础上,对热力工况的模拟计算,管网的调节性和稳定性,管网的优化等方面进行了初步的探讨.