近红外结合线性回归算法快速预测小麦籽粒干物质和重量

为了实现小麦品质(干物质、重量)的快速无损检测,对35个小麦品种样品进行了近红外系统扫描,获取光谱信息,并进行高斯滤波平滑(GFS)、归一化(N)和基线校正(BC)预处理.采用偏最小二乘(PLS)算法分别建立光谱信息与干物质和重量参考值之间的定量关系.采用回归系数法(RC)和连续投影算法(SPA)两种方法在900～17...     

ALOHA算法在RFID反碰撞问题中的应用

RFID(RadioFrequencyIdentification)—射频识别技术是一种利用射频信号自动识别目标对象并获取相关信息的技术,现在已经涉及到人们日常生活的各个方面,被称为21世纪最有前途的技术之一。但是,它在应用中存在碰撞问题,使数据读取不正确。论文对最简单的反碰撞算法ALOHA算法进行了研究,在识别时间和重发次数之间作一下折衷,确定如何选择退避时间。     

AZ91D镁合金凝固过程分析

采用差热法以及冷却曲线测定AZ91D镁合金的相变温度,通过金相试验,研究了AZ91D镁合金凝固过程中显微组织的变化,为制定合理的AZ91D镁合金热处理工艺,提高合金力学性能提供了依据.     

93上01侧向支承压力显现规律

通过对93_上01工作面矿压观测,初步掌握了深部开采综放工作面矿压显现规律     

G．655光纤的特点及其应用

随着长途通信传输容量的成倍增长,以10Gbit/s为基础的波分复用技术全面走向商用。新开发的G．655光纤是开通大容量传输的系统较好的媒介。     

Multi-Source Temporal Data Aggregation in Wireless Sensor Networks

Data aggregation has been emerged as a basic approach in wireless sensor networks (WSNs) in order to reduce the number of transmissions of sensor nodes.This paper proposes an energy-efficient multi-source temporal data aggregation model called MSTDA in WSNs. In MSTDA model, a feature selection algorithm using particle swarm optimization (PSO) is presented to simplify the historical data source firstly. And then a data prediction algorithm based on improved BP neural network with PSO (PSO-BPNN) is proposed. This MSTDA model, which helps to find out potential laws according to historical data sets, is deployed at both the base station (BS) and the node. Only when the deviation between the actual and the predicted value at the node exceeds a certain threshold, the sampling value and new model are sent to BS. The experiments on the dataset which comes from the actual data collected from 54 sensors deployed in the Intel Berkeley Research lab made a satisfied performance. When the error threshold greater than 0.15, it can decrease more than 80% data transmissions.     

Synthesis of single-crystalline α-MnO2 nanotubes and structural characterization by HRTEM

Single-crystalline α-MnO₂ nanotubes were synthesized by hydrothermal method. The growth of α-MnO₂ nanotubes is through the formation of the core (γ-MnO₂)-shell (α-MnO₂) nanofibers, and then through the formation of the cavity by the dissolution of the core. The outer and the inner diameters of as-synthesized nanotubes are in the range from 13.3 to 39.2 nm, and from 2.0 to 10.8 nm, respectively. The lattice images on the wall and in the center correspond to the (2 2 0), and the (2 1 1) interplanar spacing of the tetragonal-structure α-MnO₂.     

超支化聚亚胺酮多孔材料的制备

聚亚胺酮是一类线性高性能高分子材料.文中首先以1,3,5-三-苯甲酰氯和溴苯为原料,由傅-克酰基化反应得到三官能度的1,3,5-三-(4'溴苯酰基)苯,再以1,3,5-三-(4'溴苯酰基)苯和对苯二胺为单体,通过钯催化的胺化反应缩聚得到超支化聚亚胺酮凝胶.凝胶经过二氧化碳超临界萃取,得到了具有耐热等级的纳米级孔径的聚亚...     

Effect of fluoride coating on in vitro dynamic degradation of Mg–Zn alloy

A compact and flat fluoride coating with some pores was prepared on a Mg–Zn alloy in order to control its degradation behavior. The electrochemical tests demonstrated that the real impedance (Z_re) of the fluoride-coated Mg–Zn was approximately 10 times as large as that of the untreated alloy. The free corrosion potential (E_corr), compared to that of the uncoated Mg–Zn alloy, increased 646 mV for the coated metal. The free corrosion current (I_corr) of the Mg–Zn specimen with the fluoride film was about one tenth of that of the uncoated one. The in vitro dynamic degradation tests showed that the average weight loss of the fluoride-coated Mg–Zn was lower than that of the untreated alloy in the initial 4 h of the tests, indicating the film could function as a barrier coating on Mg–Zn matrix. However, the coating cracked and peeled severely after 4 h dynamic tests, which implied that the fluoride coating could not endure the sustaining washing of the modified simulated body fluid.     

使用湿部紧凑系统提高纸机运行效率

纸机的运行效率是纸机的生产力、正常运行时间和产品质量三位一体的体现.前提条件是系统必须足够稳定并且易于操作.