A temperature sensor based on the splicing of a core offset multi-mode fiber with two single mode fibers

In this paper, a temperature sensor based on the splicing of a core offset multi-mode fiber with two single mode fibers is proposed and demonstrated experimentally. The temperature sensing principle is analyzed and related experiment is performed. By controlling the core offset and splicing length of the specialty multi-mode fiber (SMMF), two sensors with different temperature sensing properties are obtained, and experimental results show that the temperature sensitivity can be up to 48.76 pm/°C in the range of 25—95 °C. Moreover, it has many advantages, including small size, high sensitivity, and simple structure. So it can be used in potential temperature sensing applications, such as industrial production, biomedical science, power electronics, and so on.     

Miniature Fabry-Perot interferometric sensor for temperature measurement based on photonic crystal fiber

A novel miniature Fabry-Perot interferometric (FPI) temperature sensor is proposed and demonstrated experimentally. The modal interferometer is fabricated by just splicing a section of photonic crystal fiber (PCF) with a single-mode fiber (SMF). The air holes of the PCF are fully collapsed by the discharge arc during the splicing procedure to enhance the reflection coefficient of the splicing point. The transmission spectra with different temperatures are measured, and the experimental results show that the linear response of 11.12 pm/°C in the range of 30–80 °C is obtained. This sensor has potential applications in temperature measurement field.     

Coverage control algorithm for wireless sensor networks based on non-cooperative game

For the redundancy coverage of nodes leads to the phenomenon of low energy efficiency,Non-cooperative game theory was used to solve it.A revenue function was proposed,which considering the coverage of nodes and the residual energy.The lifetime of the node and network path gain were applied to revenue function.The network topology was built by nodes with the appropriate work strategy.Control algorithm coverage in wireless sensor network was proposed based on Non-cooperative game theory.A Nash equilibrium between the coverage rate and the residual energy was proved,and the return function converged to the Pareto optimal.Experiments show that the algorithm can provide reasonable coverage of network nodes and ensure energy efficiency.     

无标度网络的级联失效缓解策略

级联失效现象是一种节点失效的动态效应,会瞬间波及全网,造成全局网络瘫痪,成为无标度网络的规模化应用瓶颈.针对无标度网络的级联失效问题,提出一种可抵御任意单个节点失效引发的级联失效的缓解策略.在无标度网络中,节点容量是恒定的,根据这一特点建立级联失效模型,推导出网络发生大规模级联失效的承载极限,进而针对按节点度降序攻击的节点失效行为,提出相应的级联失效缓解策略.仿真实验结果表明,只对网络中小部分节点度大的超载节点采取一次缓解策略,可以显著改进无标度网络对此类攻击的级联失效抵御能力,同时通过数值模拟发现,网络总节点数和节点容量与网络的级联失效抵御能力正相关.     

加权无标度网络的级联失效模型

在加权的无标度网络中,为了抵抗网络的级联失效,增强网络的鲁棒性,提出了一种参数可调的级联失效模型.该模型从全局和局域的角度,将节点介数、节点度、节点权重和邻居节点权重相结合构建节点的初始负载,并建立节点容量与初始负载的比例关系,当节点失效后,通过结合失效节点邻居的容量来制定负载重分配规则,进而通过对网络级联失效的分析,推导负载参数的演化过程,得出模型中的参数对网络鲁棒性的影响.最后,通过实验验证了所提方法的有效性.     

基于混沌优化MPSO的移动机器人FastSLAM算法研究

针对移动机器人快速同时定位和地图创建(FastSLAM)中粒子退化问题,提出一种基于混沌优化的中值导向粒子群优化(MPSO)算法。该算法在粒子估计过程中引入观测信息,调整粒子的提议分布,提高位置预测的准测性。混沌优化MPSO算法采用两步优化策略,首先通过中值导向加速度来改进粒子的进化速度,有效地克服粒子退化问题,改善算法的收敛性;然后针对粒子耗尽问题,在MPSO优化算法中引入混沌搜索算法来寻找全局最优位置,驱散聚集在局部最优的粒子群,使其向全局最优位置靠近,扩大解空间的范围,从而保持种群的多样性。仿真和实时数据证明了该方法正确、可行。     

基于混合特征的移动机器人图像匹配算法

针对移动机器人定位过程中视觉图像处理速度慢以及特征点提取与匹配实时性、准确性差的问题,提出了基于颜色矩的改进SIFT分级图像匹配算法。首先改进SIFT算法,扩大极值点检测范围;采用Sobel算子计算特征点的梯度方向和幅值;以向量夹角为准则度量SIFT特征相似性,提高SIFT特征提取与匹配的速度和精度。图像匹配时先采用颜色矩对环境图像序列进行相似性排序,改进SIFT特征,再与排序后图像依次进行精确匹配,分级匹配提高了移动机器人的定位速度和精度。实验结果表明：与原SIFT相比,改进SIFT提高了特征向量的显著性,误匹配率降低约9.2%,特征点数量减少约20%;分级匹配提高了图像匹配速度和精度,SIFT特征计算量减小60%,总体耗时缩短40%。达到移动机器人定位实时性和鲁棒性的目的。     

基于V-结构&对数似然函数定向与禁忌爬山的贝叶斯网络结构算法

针对爬山算法搜索空间过大和易陷入局部最优的问题,该文提出基于V-结构&对数似然函数定向与禁忌爬山的贝叶斯网络结构算法(VTH)。该算法利用定向最大支撑树约束搜索空间,在最大支撑树定向过程中,提出V-结构与对数似然函数(VLL)结合的定向策略;在评分搜索过程中,提出禁忌爬山(VTH)评分搜索策略,该策略将禁忌表清空机制与爬山搜索的局部择优准则结合,在提高全局寻优能力的同时也能保证搜索效率。该算法与其他算法在Asia, Car, Child和Alarm 4种标准网络中进行仿真实验,对比汉明距离、F1值、平衡评分函数(BSF)值、运行时间4个指标,验证了该算法的有效性。     

Design and research of magnetic field sensor based on grapefruit optical fiber filled with magnetic fluid

A novel magnetic field sensor was proposed based on the grapefruit optical fiber with the magnetic fluid injected into the six air holes. The sensor utilizes the Mach-Zehnder interference (MZI). The light is transmitted through the single-mode fiber to the fusion splice point and is divided into two parts. When the light passes through the cladding air hole with magnetic fluid, it interferes with the core light, and the change of the interference light is related with the change of the magnetic field. The sensor cavity length is 6 cm. It can be obtained from the experimental results that the magnetic field sensitivity reaches up to 2.243 nm/Oe with the range from 0 to 2.28 Oe. The sensor has the advantages of easy fabrication, easy installation and low cost. The findings provide new ideas for the study of ocean wind electromagnetic fields.     

显微热成像技术研究现状与展望

显微热成像系统不仅能观测物体的形状细节,还能观测温度变化的细节,因此对需要进行细微热分析的领域具有重要作用。本文对显微热成像技术研究的背景和意义进行了概括,简单介绍了显微热成像系统的组成及工作过程,总结了显微热成像技术国内外发展研究及应用的现状,最后对其存在的问题及发展动态进行了分析。