UFMC系统载波干扰抑制改进算法

针对ICI自消除算法导致UFMC系统频带利用率过低的问题,提出一种联合部分自消除和加升余弦窗的改进方案。该方案具体通过在UFMC系统发射端子带边界插入自消除子载波,并在UFMC系统接收端进行时域加窗来达到抑制UFMC系统干扰、提升系统的频带利用率的目的。对算法进行MATLAB仿真实验,当子带两侧设置4个自消除子载波时,相较自消除算法,系统载波干扰比增大,同时系统的频谱利用率也提升了10%。仿真结果表明,所提算法能够有效抑制ICI,提高系统抗干扰性能,同时提升系统频带利用率。     

基于粗糙集的特征选择方法的研究

文本自动分类是指将文本按照一定的策略归于一个或多个类别中的应用技术。文本分类是文本挖掘的基础,而特征选择又是文本分类中的核心。论文分析了以前特征选择方法中由于特征数目过多而造成分类时间和精度不高的缺点,提出了一种基于粗糙集的特征选择方法,其特点是以特征在文本分类中的重要性对特征进行选择。最后通过实验验证了该算法,证明该方法是可行的。     

An FPGA implementation for real-time edge detection

The Hessian matrix-based edge detection algorithm of Dr. Carsten Steger has the advantages of high accuracy and versatility. However, this algorithm has a complex and time-consuming computation process. Large-scale Gaussian convolution also employs a large number of multipliers when implemented on a field programmable gate array (FPGA). To address these problems, an FPGA implementation for Steger’s edge detection algorithm is proposed. This implementation employs pipeline and parallel architectures at both task and data levels for data stream processing. The original kernels of Gaussian convolution are simplified with box-filter to convert the multiplication operation in the convolution into addition, subtraction, or shift operations with the concept of integral image, thereby minimizing the multiplier resources. The proposed FPGA implementation demonstrates a favorable accuracy and anti-noise capability when dealing with different degrees of blur and noise in an image. Therefore, the FPGA implementation can satisfy real-time edge detection requirements.     

ARM Linux与WiFi的移动智能终端门禁系统设计

设计了一种基于嵌入式 ARM Linux平台和 Wi Fi通信的移动智能终端门禁系统,包括门禁装置和用户移动智能终端设备,其中门禁装置采用S3 C6410处理器,并以嵌入式 Linux为软件开发平台。移动智能终端设备则作为用户开门凭据,基于 Android系统开发门禁 APP,实现用户身份认证、注册和开门功能。测试结果表明,与现有门禁系统相比,该设计在安全性、可操作性和成本上有明显优势。     

长江上游ECMWF降水和径流预报产品评估

欧洲中期天气预报中心近年发布了季节性的GloFAS Seasonal径流和SEAS5降水集合预报产品。选取长江上游6个控制站的径流预报及4个分区的面雨量预报为研究对象,通过计算分析AUC、ROCSS和可靠性等指标,评估了这2种产品对于长江上游水库群蓄水期的枯水情景的预报能力。结果表明:2种产品提前一个月判断枯水雨情的效果较好,但产品倾向过度预测枯水事件发生的可能性,在实际生产运用中需得到重视。研究成果可为基于中长期预报的长江上游水库群提前蓄水调度提供科学依据与技术支撑。     

Highly Conductive,Scalable, and Machine Washable Graphene‐Based E‐Textiles for Multifunctional Wearable Electronic Applications

Graphene‐based textiles show promise for next‐generation wearable electronic applications due to their advantages over metal‐based technologies. However, current reduced graphene oxide (rGO)‐based electronic textiles (e‐textiles) suffer from poor electrical conductivity and higher power consumption. Here, highly conductive, ultraflexible, and machine washable graphene‐based wearable e‐textiles are reported. A simple and scalable pad?dry?cure method with subsequent roller compression and a fine encapsulation of graphene flakes is used. The graphene‐based wearable e‐textiles thus produced provide lowest sheet resistance (≈11.9 Ω sq^?1) ever reported on graphene e‐textiles, and highly conductive even after 10 home laundry washing cycles. Moreover, it exhibits extremely high flexibility, bendability, and compressibility as it shows repeatable response in both forward and backward directions before and after home laundry washing cycles. The scalability and multifunctional applications of such highly conductive graphene‐based wearable e‐textiles are demonstrated as ultraflexible supercapacitor and skin‐mounted strain sensors.     

基于协同合作的蚁群优化算法

蚁群优化是一种模拟蚂蚁觅食的群集智能搜索算法,基本蚁群算法收敛性较差,易陷入局部最优解。本文在基本蚁群算法的基础上,提出一种新的蚁群优化算法,通过在信息素局部更新中引入信息素扩散模型,在信息素全局更新中引入随机扰动机制,发挥蚂蚁之间的协同合作能力,提高了算法的收敛速度。以TSP为例的仿真实验表明,该算法具有较强的寻优能力、较好的鲁棒性和有效性。     

E波段折叠波导行波管集成极靴结构设计及仿真

为进一步提升毫米波折叠波导行波管的输出功率,通过整体加工的工艺方法,将折叠波导慢波结构和周期永磁聚焦系统在母材上同时加工,形成一种集成极靴结构。基于圆形注电子光学系统,设计了E波段折叠波导行波管的集成极靴结构。利用三维电磁场模拟软件(CST)的微波工作室,设计并模拟了慢波结构的冷特性参数,并根据慢波结构尺寸设计周期永磁聚焦系统。通过电磁工作环境仿真软件(OPERA)对磁场进行仿真验证,最终整管粒子数值模拟(PIC)计算结果表明,在61~71 GHz频带内可获得大于1 kW的饱和输出功率。该集成极靴结构在提供强轴向磁场的同时,具有结构紧凑、散热性好等优点。     

A High Current Density Direct‐Current Generator Based on a Moving van der Waals Schottky Diode

Traditionally, Schottky diodes are used statically in the electronic information industry while dynamic or moving Schottky diode–based applications are rarely explored. Herein, a novel Schottky diode named “moving Schottky diode generator” is designed, which can convert mechanical energy into electrical energy by means of lateral movement between the graphene/metal film and semiconductor. The mechanism is based on the built‐in electric field separation of the diffusing carriers in moving Schottky diode. A current‐density output up of 40.0 A m^?2 is achieved through minimizing the contact distance between metal and semiconductor, which is 100–1000 times higher than former piezoelectric and triboelectric nanogenerators. The power density and power conversion efficiency of the heterostructure‐based generator can reach 5.25 W m^?2 and 20.8%, which can be further enhanced by Schottky junction interface design. Moreover, the graphene film/semiconductor moving Schottky diode–based generator behaves better flexibility and stability, which does not show obvious degradation after 10 000 times of running, indicating its great potential in the usage of portable energy source. This moving Schottky diode direct‐current generator can light up a blue light‐emitting diode and a flexible graphene wristband is demonstrated for wearable energy source.     

参加重LAEA个人剂量监测比对研究的总结

国际原子能机构(IAEA)于1988年4月—1989年4月组织了一次个人剂量监测比对。参加这次比对的有包括中国辐射防护研究院个人剂量监测实验室在内的19个国家的21个实验室。本文介绍本实验室参加这次比对测量的情况和结果。