GPRS数据传输模块的设计与实现

本文旨在利用GPRS实现无线传输数据.首先介绍基于通用分组无线业务(GPRS)的无线数据传输技术,然后对应用单片机C51实现GPRS模块串口通信进行研究,给出硬件设计原理图,并且给出程序设计流程图.对基于C51的GPS和GPRS模块进行了仿真,提出用GPRS技术进行无线数据传输的实现方法.实践证明,利用GPRS传输数据与传统的数据传输方式相比,具有耗资小、体积小、分布广、使用灵活等优点.     

基于压缩量化的非正弦时域正交调制信号预失真方法

针对基于椭圆球面波函数的非正弦时域正交调制信号峰均功率比较高,因而受功率放大器非线性失真影响较大的问题,该文设计了一种基于波形训练的非迭代查询表预失真结构。由于所选量化方法直接决定了查询表预失真器的精度,通过分析调制信号的幅值分布特性,提出一种综合考虑功率放大器特性及信号幅值分布特性的压缩量化方法。对采用所提预失真方法前后信号的带内带外失真特性进行了仿真,并与采用幅度均匀量化方式的性能进行了比较。结果表明,该文方法有效改善了非正弦时域正交调制信号功率谱及系统误码率特性,减小了功率放大器给信号带来的非线性失真。     

改进的自适应呼吸信号均值漂移跟踪方法研究

利用呼吸门控技术进行放射治疗已成为一个热门研究问题,它能确保对健康组织细胞造成最小程度的伤害,而其中的关键问题之一是研究呼吸信号均值漂移跟踪方法,以保证门控技术在开关放射线方面的准确性。本文基于Kanatani高精度椭圆拟合分析方法,并在广义特征分解问题基础上,提出了一种改进的自适应呼吸信号均值漂移跟踪方法,利用我们提出的改进算法可以在状态空间中用椭圆对呼吸信号进行估计。在本文中我们可以得到椭圆的中心值,它对应于我们所要估计的呼吸信号均值,其对有信号损失的数据以及伪数据都具有鲁棒性,在实验中我们验证了由于利用了Kanatani提出的方法,对小数据量信号进行估计时,我们的算法同样具备良好的抗噪性,这修正了仅利用广义特征分解问题中寻找对应特征向量的最大特征值方法求解椭圆估计参数方面的不足。      

Techniques and Apparatus for Measuring Rotational Core Losses of Soft Magnetic Materials

In many situations such as the cores of a rotating electrical machine and the T joints of a multiphase transformer, the local flux density varies with time in terms of both magnitude and direction, i.e. the flux density vector is rotating. Therefore, the magnetic properties of the core materials under the rotating flux density vector excitation should be properly measured, modeled and applied in the design and analysis of these electromagnetic devices. This paper presents an extensive review on the development of techniques and apparatus for measuring the rotational core losses of soft magnetic materials based on the experiences of various researchers in the last hundred years.     

熔石英玻璃和白宝石晶体激光损伤的研究

研究不同实验条件对熔石英和白宝石激光损伤阈值和损伤形貌的影响 ,获得了一些有用的实验结果 ,对相应的损伤机理作了分析。同时对熔石英的抗激光加固也进行了研究。结果表明 ,激光预辐照和酸侵蚀处理使熔石英的激光损伤阈值分别提高 70 %和 80 %以上     

Modification of Energy Level Alignment for Boosting Carbon-Based CsPbI2Br Solar Cells with 14% Certified Efficiency

Hole transfer material (HTM)-free, carbon-based all-inorganic perovskite solar cells (C-PSCs) are promising alternatives to conventional organic–inorganic hybrid PSCs in addressing thermal and moisture instability issues. However, the energy level mismatch between the inorganic perovskite and carbon electrode coupled, together with the incapability of the carbon electrode to reflect incident light for reabsorption, limits the power conversion efficiency (PCE) of C-PSCs. To address these issues, herein, a new strategy of a hexyltrimethylammonium bromide (HTAB)-modified CsPbI₂Br perovskite surface is devised to reduce this energy offset from 0.70 to 0.32 eV and increase the built-in potential by 70 mV for the final devices. Additionally, a CsPbI₂Br perovskite film with a thickness of up to 800 nm is realized via a hot-flow-assisted spin coating approach in an ambient atmosphere with humidity of less than 80%. Reduced energy offset coupled with suppressed charge recombination and thick perovskite layer boosts the champion PCE of CsPbI₂Br C-PSCs to 14.3% (J_sc = 14.1 mA cm⁻², V_oc = 1.26 V, and fill factor = 0.806), and the average PCE to 13.9% under one sun illumination. A new certified efficiency record of 14.0% is obtained for HTM-free inorganic C-PSCs. Meanwhile, the moisture-resistant barrier from the alkyl chain in HTAB improves the stability of the final devices.     

一种基于GRU神经网络的电力负荷预测

针对电力负荷序列不稳定且传统的神经网络在电力负荷预测中预测精度较低等问题,提出了门控循环单元神经网络(Gated Recurrent Unit Neural Network,GRU)负荷预测的方法.利用python编程语言在Tensorflow框架在搭建门控循环单元神经网络,将影响电力负荷的特征数据输入模型中进行训练....     

Tuning the Optoelectronic Properties of Carbazole/Oxadiazole Hybrids through Linkage Modes: Hosts for Highly Efficient Green Electrophosphorescence

A series of bipolar transport host materials: 2,5‐bis(2‐(9H‐carbazol‐9‐yl)phenyl)‐1,3,4‐oxadiazole (o‐CzOXD) ( 1 ), 2,5‐bis(4‐(9H‐carbazol‐9‐yl)phenyl)‐1,3,4‐oxadiazole (p‐CzOXD) ( 2 ), 2,5‐bis(3‐(9H‐carbazol‐9‐yl)phenyl)‐1,3,4‐oxadiazole (m‐CzOXD) ( 3 ) and 2‐(2‐(9H‐carbazol‐9‐yl)phenyl)‐5‐(4‐(9H‐carbazol‐9‐yl)phenyl)‐1,3,4‐oxadiazole (op‐CzOXD) ( 4 ) are synthesized through simple aromatic nucleophilic substitution reactions. The incorporation of the oxadiazole moiety greatly improves their morphological stability, with T_d and T_g in the range of 428–464 °C and 97–133 °C, respectively. The ortho and meta positions of the 2,5‐diphenyl‐1,3,4‐oxadiazole linked hybrids ( 1 and 3 ) show less intramolecular charge transfer and a higher triplet energy compared to the para‐position linked analogue ( 2 ). The four compounds exhibit similar LUMO levels (2.55–2.59 eV) to other oxadiazole derivatives, whereas the HOMO levels vary in a range from 5.55 eV to 5.69 eV, depending on the linkage modes. DFT‐calculation results indicate that 1 , 3 , and 4 have almost complete separation of their HOMO and LUMO levels at the hole‐ and electron‐transporting moieties, while 2 exhibits only partial separation of the HOMO and LUMO levels possibly due to intramolecular charge transfer. Phosphorescent organic light‐emitting devices fabricated using 1 – 4 as hosts and a green emitter, Ir(ppy)₃ or (ppy)₂Ir(acac), as the guest exhibit good to excellent performance. Devices hosted by o‐CzOXD ( 1 ) achieve maximum current efficiencies (η_c) as high as 77.9 cd A^?1 for Ir(ppy)₃ and 64.2 cd A^?1 for (ppy)₂Ir(acac). The excellent device performance may be attributed to the well‐matched energy levels between the host and hole‐transport layers, the high triplet energy of the host and the complete spatial separation of HOMO and LUMO energy levels.     

Multisource multicasting in IP/MPLS over WDM networks

Multicasting applications such as multimedia conferencing, online multiplayer interactive games, and distance learning are becoming increasingly popular. With multiprotocol label switching, Internet protocol networks can offer quality of service and traffic engineering capabilities. This article introduces several approaches for multisource multicast sessions in the context of IP over WDM networks and evaluates their performance in terms of blocking probability, time complexity, and memory consumption. Our simulation study shows that among all the approaches, the newly proposed approach, known as one Bidirectional Tree with Just enough bandwidth reserved on each link of the tree, achieves the best overall performance.     

对网络整合的思考与建议

针对广电网络重组整合与发展速度、股权债务与业务分工、内外环境与不利因素等，提出网络行政整合必须从当地的实际出发，从网络的需求出发，制定统一的政策、统一的联网标准，分级分步实施网络整合。根据广电网络传播环境的变化，分析当前所存在的问题、所处的环境、资金危机、人才危机。指出发展对策和亟需做好的工作。