基于QD-SOA-XGM的全光逻辑或非门研究

为了改善基于交叉增益调制效应的量子点半导体光放大器全光逻辑或非门的性能,研究了QD-SOA-XGM全光逻辑门的码型效应特性,用两个连“1”脉冲和单个“1”脉冲的峰值功率来衡量,即P30/P20。研究结果表明:第一级输入电流越小,逻辑或非门的性能越好,而第二级输入电流对或非门性能影响很小;在一定范围内,输入连续光功率越大、有源区长度越长、有源区宽度越宽、最大模式增益越大、损耗系数越小,或非门输出效果越好。     

基于Kalman和双级联随机森林的在线目标跟踪算法

针对传统的基于检测的在线目标跟踪算法容易产生跟踪漂移的现象,提出了一种新的在线目标跟踪算法.以基于主方向模板特征的双级联随机森林分类器作为检测器,卡尔曼滤波器作为跟踪器.首先利用卡拉曼算法跟踪目标,然后以跟踪的目标位置为中心向外扩展一定的范围作为双级联随机森林分类器的检测区域,利用全局随机森林分类器和局部随机森林分类器进行目标检测,并将检测结果作为Kalman跟踪算法下一帧的观测值.实验结果显示,提出的算法在跟踪大小420×320的图像时,跟踪速度达到24.3 f/s(帧/秒),目标中心位置误差在30 pixel时,算法准确率可达到80％以上.     

查干湖冬捕音频制作纪实

查干湖冬捕作为千年以来流传下来最古老的捕鱼方式,被列为国家非物质文化遗产,并且近些年通过电视转播,广为人知.此次转播查干湖冬捕,包括工作者从前期构思,现场勘查,初步设计,到转播中的灵活机动,克服极端天气环境,再到最后成功完成任务.详细记录和描述了此次查干湖冬捕音频信号的制作过程.     

Clos网络中变长分组交换及调度算法研究

Clos网络是多端口的路由器和交换机中经常采用的交换网络,其优点在于它是一个结构全对称的网络。比较了多级Clos网络分布式调度算法中定长分组和变长分组交换的特点;给出一种基于变长分组交换的MSM型三级Clos交换网络结构和相应的ACBS调度算法;消除了分组负载分配的不公平性。分析表明该调度算法优于传统算法,并通过仿真实验验证了算法的有效性。     

卷烟主流烟气中NNK测量不确定度评定

对气相色谱-热能分析联用法测定卷烟主流烟气总粒相物中NNK含量的测量不确定度进行评定,分析了NNK含量检测的影响因素,计算了不确定度分量及合成不确定度,当NNK含量测定结果为27．4ng／支时,扩展不确定度为2．0ng／支。     

Attack on the Enhanced Multiparty Quantum Secret Sharing

Recently, Gao et al.'s [Commun. Theor. Phys. 52 (2009) 421] multiparty quantum secret sharing (MQSS) protocol with two-photon three-dimensional Bell states was enhanced by Hwang et al. [Commun. Theor. Phys. 56 (2011) 79]. The improved protocol removes some unnecessary unitary operations, devices, and transmissions by the technique of decoy single photons and careful modification. However, in this paper, we investigate the security of the improved protocol and find it is insecure. The eavesdropper can steal all Alice's secret information. Furthermore, a feasible modification to remedy the security loophole is put forward. Our improved protocol provides a basic method to modify a kind of MQSS protocols which cannot resist the collusion attack.     

选区外延生长的PbTe-超导杂化纳米线:一个可能实现拓扑量子计算的新体系

半导体-超导体杂化纳米线是用于研究马约拉纳零能模和拓扑量子计算的主要平台之一,而基于Ⅲ-Ⅴ族半导体InAs和InSb的纳米线则是当前此方向研究的主流材料体系.尽管经过多年制备技术的改进和优化,样品中过多的缺陷和杂质仍是阻碍此方向进一步发展的核心问题.近年来,一个新的马约拉纳纳米线候选体系——Ⅳ-Ⅵ族半导体PbTe-超导杂化纳米线吸引了很大关注并获得了快速的研究进展.PbTe的介电常数巨大,且具有晶格匹配的衬底,这些优势使其有潜力突破纳米线样品质量提升的瓶颈,成为马约拉纳零能模的研究和拓扑量子计算实现的理想平台.本文将简单介绍最近几年在PbTe纳米线和PbTe-超导杂化纳米线器件的选区分子束外延生长、输运性质研究方面取得的重要进展,并对这种新的马约拉纳纳米线候选体系的优势、问题及基于其实现拓扑量子计算的前景进行讨论.     

Accelerated oxygen precipitation in fast neutron irradiated Czochralski silicon

Annealing effect of the oxygen precipitation and the induced defects have been investigated on the fast neutron irradiated Czochralski silicon （CZ-Si） by infrared absorption spectrum and the optical microscopy. It is found that the fast neutron irradiation greatly accelerates the oxygen precipitation that leads to a sharp decrease of the interstitial oxygen with the annealing time. At room temperature （RT）, the 1107cm^-1 infrared absorption band of interstitial oxygen becomes weak and broadens to low energy side. At low temperature, the infrared absorption peaks appear at 1078cm^-1, 1096cm^-1, and 1182cm^-1, related to different shapes of the oxygen precipitates. The bulk microdefects, including stacking faults, dislocations and dislocation loops, were observed by the optical microscopy. New or large stacking faults grow up when the silicon self-interstitial atoms are created and aggregate with oxygen precipitation.     

载入树状分子内部的纳米金修饰玻碳电极的制备及其对亚硝酸根的电化学测定

建立了一种简单、可靠的基于载入树状分子内部的纳米金修饰电极用于亚硝酸根测定的电化学分析方法.将壳聚糖(Chit)修饰在玻碳电极表面,在偶联活化剂碳二亚胺存在的条件下,4.5代羧基末端的树状分子(Dendrimer)通过其外围的羧基与壳聚糖的氨基形成酰胺键而连接在电极表面.Au(Ⅲ)通过与树状分子内部氮的配位作用被结合在...     

Revisit to frozen-in property of vorticity

Considering some simple topological properties of vorticity vector, the frozen-in property of vorticity herein is revisited. A vortex line, as is analogous to velocity vector along a streamline, is defined as such a coincident material(curve) line that connects many material fluid elements, on which the local vorticity vector for each fluid element is also tangent to the vortex line. The vortex line evolves in the same manner as the material line that it is initially associated with. The vortex line and the material line are both oriented to the same directions, and evolve with the proportional magnitude, just like being ‘frozen' or ‘glued' to the material elements of the fluid under the barotropic assumption. To relax the limits of incompressible and barotropic atmosphere, the frozen-in property is further derived and proved in the baroclinic case. Then two effective usages are given as examples. One is the derivation of potential vorticity conservation from the frozen-in property in both barotropic and baroclinic atmospheres, as a theory application, and the other is used to illuminate the vorticity generation and growth in ideal cases and real severe weather process, e.g., in squall line, tornado, and other severe convection weather with vortex. There is no necessity to derive vorticity equation, and this method is very intuitive to explain vorticity development qualitatively, especially for fast analysis for forecasters. Certainly, by investigating the evolution of vortex line, it is possible to locate the associated line element vector and its development on the basis of the frozen-in property of vorticity. Because it is simple and visualized, it manifests broad application prospects.