Role of dual SiOx: H based buffer at the p/i interface on the performance of single junction microcrystalline solar cells

In p-i-n structure a-Si solar cell a buffer layer with proper characteristics plays important role in improving the p/i interface of the cell, reducing mismatch of band gaps and number of recombination centres. However for p-i-n structure microcrystalline ( µc-Si: H) cell which has much less light induced degradation than a-Si:H cell, not much work has been done on development of proper buffer layer and its application to µc-Si:H cell. In this paper we have reported the development of two intrinsic oxide based microcrystalline layer having different characteristics for use as buffer layers at the p/i interface of µc-Si:H cell. Previously SiO_x:H buffer layer has been used at the p/i interface which showed positive effects. To explore the possibility of improving the performance of p-i-n structure µc-Si:H cell further we have thought it interesting to use two buffer layers with different characteristics at the p/i interface. The two buffer layers have been characterized in detail and applied at the p/i interface of the µc-Si:H cell with positive effects on all the PV parameters mainly improves the open circuit voltage (V_oc) and enhances short circuit current (I_sc). The maximum initial efficiency obtained is 8.97% with dual buffer which is 6.7% higher than that obtained by using conventional single buffer layer at the p/i interface. Stabilized efficiency of the cell with dual buffer is found to be ~9.5% higher than that with single buffer after 600 h of light soakings.     

A highly nonlinear photonic quasi-crystal fiber with low confinement loss and flattened dispersion

We proposed a novel photonic quasi-crystal fiber with near-zero flattened dispersion, highly nonlinear coefficient, and low confinement loss by using the dual concentric core structure. By optimizing the structure parameter, the proposed photonic quasi-crystal fiber can achieve a nonlinear coefficient larger than 33 W⁻¹ km⁻¹ and near-zero flatten dispersion of 0 ± 3.4 ps/nm/km with a near-zero dispersion slope of 8.5 × 10⁻³ ps/nm²/km at the wavelength of 1550 nm. Near-zero flattened dispersion and low confinement loss in the ultralow order of 10⁻⁷ dB/m are simultaneously obtained in the wavelength range from 1373 to 1627 nm. Furthermore, two zero dispersion wavelengths can be achieved in a wide wavelength ranger from 1373 to 1725 nm. From the point of view of practical fabrication, the influence of deviation of each air hole diameter within 3% of imperfections on dispersion, nonlinearity, and is discussed to verify the robustness of our design.     

机载平台下基于深度检测网络的目标跟踪重捕算法

目标检测与跟踪是机载光电设备至关重要的功能模块,其检测跟踪的性能直接关系到目标感知的精度.近年来基于Siamese网络的改进跟踪算法在各种挑战性的数据集上取得了优异的效果,但大多数改进算法采用局部搜索策略,无法更新模板,且模板会引入背景干扰,最终因跟踪点漂移导致跟踪失败.为了解决这些问题,本文提出了一种结合目标边缘检测的改进全连接Siamese跟踪算法,该算法利用目标的轮廓模板代替边界框模板,减少了背景杂波的干扰;同时,在Siamese网络的基础上增加了一路改进tiny-YOLOv3目标检测网络,利用K均值聚类找到最合适的锚框(anchor box),引入了扩张模块层来扩展感受野,增加了系统的抗遮挡能力,提高机载光电设备的目标捕获概率.在基准测试数据集以及挂飞数据集基础上的仿真测试性能表明本文提出的改进模型特别适合机载光电设备在跟踪与重捕复杂环境下的运动目标,在长期跟踪中能够更好地适应目标的变形和遮挡,提升系统响应时间与适应性.     

新型声表面波湿度传感器的研究

乐甫(Love)波其质点振动方向垂直于传播方向,同时又平行于基片表面,在基片法线方向上无振动分量。因此当基于Love波的电子器件在接触液体时Love波能量损耗很少,因而乐甫波声表面波(SAW)传感器主要用于液相检测。在石英上表面及在其上面淀积的SiO2薄膜中激发、传播的乐甫波对SiO2薄膜质量的变化很敏感,因此该文研究了基于乐甫波的湿度传感器感知气体环境的湿度含量。该文乐甫波湿度传感器采用42.75°Y-旋转切割石英基片,传播方向为[0°,132.75°,90°]。吸湿膜采用APCVD制作的多孔SiO2薄膜,此类膜比PECVD制作的SiO2膜疏松,吸湿、脱湿迅速。传感器灵敏度为62kHz/%RH,最大湿滞约3%,测得的湿敏特性、迟滞特性表明,Love波SAW湿度传感器线性度较好,实验验证了该结构具有很好的气体测试前景。     

ZigBee在通信电缆温度监测中的应用

为了达到监测电缆线的分布节点的温度的目的,采用了一种基于ZigBee技术的,低功耗、突发式、2.4GHz无线收发模块和集成数字温度测量传感器组成的温度测量节点组成的分布网络,并运用集中监测的方法,进行了设计分析和实验验证,取得了在链形链接间隔100米范围内10个节点的数据传输和温度监测。结果表明,在电缆线温度监测过程中,ZigBee无线组网和数字温度测量传感器能够满足测量要求,并有非常灵活的组网方式,适合于电缆线链路长的多点监测。     

基于荧光猝灭原理的硝基芳烃类爆炸物检测实验研究

基于荧光猝灭原理,以共轭荧光聚合物MEH-PPV为荧光指示剂,采用塑料光纤作为传感和传光元件进行硝基芳烃类爆炸物检测。实验采用探测荧光指示剂荧光寿命的方法进行爆炸物检测,荧光指示剂的荧光寿命利用相移法进行测量。测量了不同荧光指示剂浓度时系统对爆炸物检测的灵敏度,发现当MEH-PPV质量浓度为10 mg/L时,系统的灵敏度最高;研究了U形、双锥形、螺旋形塑料光纤传感头对系统灵敏度的影响,发现双锥形传感头的灵敏度最高;测试了荧光指示剂MEH-PPV的稳定性,实验表明光照会加快MEH-PPV的漂白速度。     

基于低速光调相信号注入DFB-LD产生4～16倍频的40GHz和60GHz毫米波信号

提出一种基于低速光调相信号注入半导体分布反馈激光器(DFB-LD)产生最低4倍频,最高16倍频的40GHz和60GHz的毫米波调相信号。该方案利用注入光的N阶调相边带锁定DFB-LD的波长,同时DFB-LD放大此调相边带并与原注入光信号通过相干差拍作用在LD腔内形成毫米波调相信号。通过理论建模分析了工作原理,经系统实验验证了此方案的可行性。应用2.5,5和10GHz的光调相信号均得到40GHz或60GHz的毫米波信号,实现了最低4倍频,最高16倍频的毫米波信号产生,并通过单边带相位噪声的测量验证了毫米波的频率稳定度。     

自适应高斯融合双通道的去雾算法

针对传统图像去雾算法存在的对比度下降和颜色偏移等问题,提出一种结合高斯融合的自适应双通道雾霾图像复原算法。首先,考虑到大气光应小于有雾图像最大值,且大于有雾图像最小值,根据亮度控制因子自适应控制的方式得到融合中通道,并获得中通道下的局部大气光;其次,提出双通道线性传输,即用最大值通道辅助完成线性传输,再用高斯函数加权融合的方法实现清晰图像最优通道估计,从而得到最优透射率;最后,结合复原模型恢复清晰图像。实验表明,所提方法有效解决了图像对比度下降与颜色偏移等问题,去雾效果良好、亮度适宜且颜色保真度更高。另外,该方法在定量指标上同样具有优越的表现。      

On optimizing system energy of voltage–frequency island based 3-D multi-core SoCs under thermal constraints

Three dimensional (3-D) multi-core SoC has been recognized as a promising solution for implementing complex applications with lower system energy. Recently, voltage–frequency island (VFI)-based design paradigm was widely adopted for energy optimization. However, the existing work commonly targeted 2-D platform, which cannot handle the exacerbated thermal issues and the increased solution space from 3-D integration. In this paper, we propose an optimization framework targeting VFI-based 3-D multi-core SoCs to minimize system energy meanwhile still meeting task deadline and thermal constraints. Our framework conducts at an earlier design phase in which designers have the freedom to determine the core stacks and map them into the hardware platform. Besides energy-aware task scheduling, we also conduct core stacking and task adjusting to balance the powers across the chip for thermal optimization. Moreover, by treating each core stack as a unity, the complicated problem of core mapping and VFI partitioning in 3-D platform can be simplified as a 2-D one. Experimental results demonstrate that on average our framework can achieve an energy reduction of 15.8% over the prior thermal balancing algorithm [17] (X. Zhou, J. Yang, Y. Xu, et al. Thermal-aware task scheduling for 3D multicore processors, IEEE Trans. Parallel Distrib. Syst. (TPDS), 21(1) (2010), 60–71.). Moreover, on average a reduction of 4.8 °C in peak temperature is achieved by our framework, compared with the state-of-the-art energy optimization scheme [8] (U.Y. Ogras, R. Marculescu, P. Choudhary, et al. Voltage–frequency island partitioning for GALS-based networks-on-chip, in: ACM/IEEE Design Automation Conference (DAC), 2007, pp. 110–115.).