Unification of Blockchain and Internet of Things (BIoT): requirements,working model,challenges and future directions

Wireless Networks - The Internet of Things (IoTs) enables coupling of digital and physical objects using worthy communication technologies and introduces a future vision where computing systems,...     

可写式胆甾相液晶显示和检测图像用算法的研究

研究了可写式胆甾相液晶显示(ChLCD)以及检测图像用的算法.我们可以用任何一个硬尖状物体(如指尖),直接在ChLCD表面上写入图像.通过测量测试盒(12mm×15mm/1×1)像素的电容,能够检测到F-状态和P-状态.但是测量4.1in ChLCD(241μm × 241μm/320 × 320)的电容时,却未能够检测到F-状态和P-状态,这主要是由于寄生电容的影响.最后,为了检测到ChLCD上的图像,研究了高频率测量方法和算法.     

Simulation and Design of Nanocircuits With Resonant Tunneling Devices

New nanotechnology-based devices are being researched to replace CMOS devices in order to overcome CMOS technology's scaling limitations. However, many such devices exhibit nonmonotonic I-V characteristics and uncertain properties which lead to the negative differential resistance (NDR) problem and the chaotic performance. This paper proposes two new circuit simulation approaches that can effectively simulate nanotechnology devices with uncertain input sources and negative differential resistance problem. A new tool called NanoSim-RTD is developed based on the proposed new simulation techniques. The experimental results show a speedup of 1.48-37.1 times when compared with existing simulators. Further, this paper demonstrates a new way to design delay-insensitive nanocircuits, and the designs can be verified by using NanoSim-RTD.     

复杂场景下的自动红外舰船目标检测

为实现多种复杂海天背景下红外舰船目标的有效检测,提出了一种基于局部边缘梯度特征分析的舰船目标检测方法。利用红外舰船目标图像的特征,改进自适应 Butterworth 高通滤波对图像进行预处理。通过计算局部边缘梯度特征和聚类分析确定初始目标区域,比较梯度特征参数并进行多尺度搜索准确检测出舰船目标。对多种复杂海天场景红外图像进行仿真实验,结果表明,该算法能够有效准确地检测出多种复杂海天场景下的红外舰船目标,且算法简单,易于实现,适应面广。     

大芯径光纤基模功率传输特性与折射率分布形式关系的研究

研究和分析了光纤芯区径向折射率分布对大芯径光纤基模的功率传输特性(主要包括最大功率密度和等效模面积这两个参数)的影响。采用一种可适用于多种光纤实际折射率分布的独特数学表达式,研究了折射率分布形状变化时大芯径光纤基模在横截面内功率密度分布与等效模面积的变化,并将结果与阶跃型折射率光纤进行对比。计算结果表明,在传输功率相同、光纤基模与高阶模等效折射率差大于10-4的前提下,折射率在芯区中心有一定凹陷的分布可以有效降低横截面内基模功率密度的最大值,增大基模的等效模面积。这一研究为设计和制作可以传输更大功率的大芯径的无源和有源单模光纤提供了理论基础。     

EEFFL: energy efficient data forwarding for forest fire detection using localization technique in wireless sensor network

Wireless Networks - Early prediction of a forest fire is one of the critical research challenges of the wireless sensor network (WSN) to save our ecosystem. In WSN based forest fire detection...     

Algorithms to Minimize Data Transfer for Code Update on Wireless Sensor Network

In Wireless Sensor Networks, the preloaded program code and data on sensor nodes often need to be updated due to changes in user requirements and environmental conditions. Sensor nodes are severely restricted by energy constraints. It is especially energy consuming for sensor nodes to transfer data through wireless radios. To efficiently reprogram sensor nodes through radio, we propose an algorithm, Minimum Data transferred by Copying and Downloading (MDCD) and its extension E-MDCD, to minimize the number of bytes needed to be transferred from the host machine to the sensor nodes. Experimental results show that the E-MDCD algorithm reduces the number of bytes transferred by 93.25 % for small code change compared with the Rsync based algorithm. In average, E-MDCD can reduce 59.82 % compared with the existing the Rsync based algorithm and 16.14 % compared with the Vdelta algorithm.     

Low complexity hybrid layered tabu-likelihood ascent search for large MIMO detection with perfect and estimated channel state information

In this work, we proposed a low-complexity hybrid layered tabu-likelihood ascent search (LTLAS) algorithm for large multiple-input multiple-output (MIMO) system. The conventional layered tabu search (LTS) approach involves many partial reactive tabu searches (RTSs), and each RTS requires an initialization and searching phase. In the proposed algorithm, we restricted the upper limit of the number of RTS operations. Once RTS operations exceed the limit, RTS will be replaced by low-complexity likelihood ascent search (LAS) operations. The block-based detection approach is considered to maintain a higher signal-to-noise ratio (SNR) detection performance. An efficient precomputation technique is derived, which can suppress redundant computations. The simulation results show that the bit error rate (BER) performance of the proposed detection method is close to the conventional LTS method. The complexity analysis shows that the proposed method has significantly lower computational complexity than conventional methods. Also, the proposed method can reduce almost 50% of real operations to achieve a BER of 10⁻³.     

高剂量离子注入直接形成Ge纳米晶的物理机理

研究了单束双能高剂量Ge离子注入、不经过退火在非晶态SiO2薄膜中直接形成镶嵌结构Ge纳米晶的物理机制．实验中利用不加磁分析器的离子注入机，采用Ge弧光放电离化自动形成的Ge+和Ge2+双电荷离子并存的单束双能离子注入方法，制备了1e16～1e18cm－2多种剂量Ge离子注入的Si基SiO2薄膜样品．用GIXRD表征了Ge纳米晶的存在，并仔细分析得到了纳米晶形成的阈值剂量．通过TEM分析了Ge纳米晶的深度分布和晶粒尺寸．用SRIM程序分别计算了双能离子在SiO2非晶层的射程和深度分布，与实验结合，得到纳米晶形成的物理机制，即纳米晶的形成与单束双能离子注入时Ge＋和Ge2＋相互碰撞产生的能量沉积在SiO2中形成的局域高温有关．     

基于单片机的超声波测距系统的研究与设计

超声波测距是一种有效的非接触式测距方法。文中分析研究了超声波测距的原理,设计了一款基于单片机AT89S52的带有温度补偿和显示报警功能的超声波测距系统,并对该系统的硬件组成和软件控制流程中的关键点进行了详细阐述。最后还对系统的测量范围、精度和可靠性等进行了测试,分析了误差产生的原因,并对系统的完善提出了一些改进建议。