Motion compensated film restoration

Motion picture films are susceptible to local degradations such as dust spots. Other deteriorations are global such as intensity and spatial jitter. It is obvious that motion needs to be compensated for before the detection/correction of such local and dynamic defects. Therefore, we propose a hierarchical motion estimation method ideally suited for high resolution film sequences. This recursive block-based motion estimator relies on an adaptive search strategy and Radon projections to improve processing speed. The localization of dust particles then becomes straightforward. Thus, it is achieved by simple inter-frame differences between the current image and motion compensated successive and preceding frames. However, the detection of spatial and intensity jitter requires a specific process taking advantage of the high temporal correlation in the image sequence. In this paper, we present our motion compensation-based algorithms for removing dust spots, spatial and intensity jitter in degraded motion pictures. Experimental results are presented showing the usefulness of our motion estimator for film restoration at reasonable computational costs. Received: 9 July 2000 / Accepted: 13 January 2002 Correspondence to:S. Boukir     

An anti-plane crack perpendicular to the weak/micro-discontinuous interface in a bi-FGM structure with exponential and linear non-homogeneities

Treated was an anti-plane crack perpendicular to the interface of an exponential-type FGM strip bonded to another linear-type FGM substrate with infinite thickness. Through Fourier integral transform, the problem was reduced as a Cauchy singular integral equation, which was further solved numerically by the Lobatto–Chebyshev collocation method. Based on the numerical solution, the effects of the geometrical and physical parameters on the stress intensity factor (SIF) were analyzed and the following conclusions were obtained: (a) A notable discrepancy between the interface-perpendicular crack and the interfacial one is that, to reduce the weak-discontinuity of interface or to make the interface micro-discontinuous will not necessarily decrease the SIF of the former, but will surely decrease that of the latter. (b) When a crack tip is situated very near to the interface (or free surface), its SIF will be high and totally dominated by the interface (or free surface). (c) To increase the stiffness of the FGM on one side of the interface is beneficial to preventing the crack on the other side from growing toward the interface. Besides, some practical suggestions were further given for material design in the field of composites.     

Assessing pre- and post-deformation in the southern Arava Valley segment of the Dead Sea Transform, Israel by differential interferometry

Differential radar interferometry, using archived ERS data over the region of the Dead Sea Transform, allows to detect ground movement (subsidence or uplift) in playas within the southern Arava Valley segment of the Dead Sea Rift. These measurements are consistent with a mean displacement rate of about 0.4 cm/month, in the direction of the radar beam, during the 8-month period preceding the Nuweiba earthquake of 22 November 1995. In the 3 years following the earthquake, the measured rate was smaller by a factor of 10. These movements are not related to salt diapirs or water pumping activities in the area. The exact location, along faults, suggests a possible correlation with pre-seismic and post-seismic fault deformation.A simple fault model consistent with the observed phenomena associates the observed subsidence/uplift to right and left stepping en-echelon fault patterns related to inter-seismic tensional accumulation along the faults. Further observations are necessary on this site and similar fault areas to corroborate the correlation between seismic activity and the observed phenomena. Monitoring of these sites should continue with differential Global positioning system (GPS) measurements and radar interferometric analysis using Envisat and Radarsat as well as archived data (including J-ERS).     

二维轴对称折迭－组合腔CO2激光器失调时的输出光束的近场分析

给出平凹谐振腔和凹平凹谐振腔失调时光轴确定方法。在二维轴对称折迭－组合腔 激光器小角度失调运行时，对非相干并和和相干并和后的输出光束的近场强度分布做了分析和模拟。结果表明：小角度失调对4cm以内的近场影响不大，光强分布仍具有高斯状分布；对4cm以外的近场影响较大，光强分布发生相应的形变，且随着失调角度变大而变大。     

一种基于偏振调制的单模光纤偏振漂移补偿算法

本文提出了一种单模光纤偏振漂移补偿新算法，该算法不仅适用于简单的一维调制，也同样适用于复杂的二维调制。同时该算法不再局限于极化分割式的斯托克斯接收机。这对于充分发挥偏振调制的潜力和降低系统造价，提高系统性能有着重要意义。这一算法的计算机模拟结果也在本文中给出。一些和算法有关的问题在本文中作了必要的讨论。     

挑坎型掺气减蚀设施过流掺气特性研究

采用一维激光测速系统，对掺气减蚀工程中常用的直线型挑坎的流场特性进行试验研究．通过测量挑坎上及空腔区水流的流速分布及紊动特性，探讨通气量与紊动强度的关系．同时在深入研究流场特性和掺气机理的基础上，通过分析影响掺气的因素，从理论上探求临界掺气流速的计算，重点分析挑坎型掺气过流在空腔负压较大的情况下，临界掺气条件的理论预测，并通过试验资料验证了该计算方法．在此基础上，还进一步研究了掺气量的计算公式及其变化规律．     

万安水利枢纽底孔坝段中隔墙流激振动响应分析

 研究了万安水利枢纽底孔坝段中隔墙在水流脉动壁压作用下的结构随机振动问题，进行了一种泄流工况下的隔墙结构流激振动响应统计量的理论计算，模拟计算了隔墙－水流－基础耦合系统固有频率对流激振动响应的影响，并对水流脉动壁压随机荷载作用下的结构动力可靠度进行了理论分析。     

用瞬态频率波动法诊断齿轮故障

利用瞬态频率波动法实现频率调制信号的解调，提取齿轮的局部裂纹信息，并通过黄河ＴＮ２５２型汽车变速器疲劳试验的信号分析来验证。     

在3．39μm波段甲烷吸收特性的测量与应用研究

报道了甲烷气体在３．３９μｍ波段吸收特性的研究结果，及其在３．３９μｍ波段多波长干涉测量中的应用。通过改变甲烷吸收室的充气参数，使激光器工作在双等光强工作点，并完成了绝对距离的干涉测量。     

里运河底泥CODCr和NH3-N释放对水质的影响实验

通过利用长江水体作为上覆水的里运河表层底泥的释放实验研究，分析了表层底泥中CODCr和NH3—N在静置和3种扰动条件下的释放规律，结果发现城区段底泥中CODCr和NH3—N的释放强度大于非常区段，底泥孔隙水与上覆水之间的浓度梯度增大促进了底泥中污染物质的更快更多地释放。同时得出了各个断面表层底泥中CODCr，和NH3-N的释放强度，在扰动条件下的释放强度远大于静置条件下的释放强度，底泥中污染物质的释放可能会在一定程度上影响里运河将来的调水水质。