A new block-based method for copy move forgery detection under image geometric transforms

Copy move forgery detection (CMFD) is one of the most active subtopic in forgery scheme. The methods of CMFD are divided into to block-based method and keypoint-based method in general. Compared with keypoint-based method, block-based method can detect undetectable detail without morphology segmentation. But many block-based methods detect the plain copy-move forgeries only. They have been incompetent to detect the post-processing operations such as various geometrical distortions, and then fail to detect the forgery regions accurately. Therefore, this paper presents an improved block-based efficient method for CMFD. Firstly, after pre-processing, an auxiliary overlapped circular block is presented to divide the forged image into overlapped circular blocks. The local and inner image feature is extracted by the Discrete Radial Harmonic Fourier Moments (DRHFMs) with the overlapped circular block from the suspicious image. Then, the similar feature vectors of blocks are searched by 2 Nearest Neighbors (2NN) test. Euclidean distance and correlation coefficient is employed to filter these features and then remove the false matches. Morphologic operation is employed to delete the isolated pixels. A series of experiments are done to analyze the performance for CMFD. Experimental results show that the new DRHFMs can obtain outstanding performance even under image geometrical distortions.     

基于支点的数据中心网络地址快速自动配置方法研究

目前云计算数据中心规模大,网络设备多,手动配置设备地址不但耗时耗力,而且容易出错。已有自动配置工作未能充分利用数据中心网络拓扑结构特征,导致从规划设计到实际设备配置的映射过程回溯步骤多,效率低。为此,提出了一种基于支点的数据中心网络地址快速自动配置方法PFAC(Pivot-based Fast Automatic Configuration)。PFAC通过预处理分析数据中心网络拓扑层次关系,依据拓扑特征优选支点完成快速匹配,并基于支点缩小配置映射节点的候选集,有效提高了配置效率。基于FatTree结构的模拟实验表明,PFAC能够根据数据中心网络规划蓝图,自动快速地为物理设备分配地址。与经典数据中心网络地址配置方法相比,PFAC算法平均耗时缩短了35%。     

通用扫描线多边形填充算法

传统的扫描线多边形填充算法只适用于水平扫描线的逐行填充。文章提出通用扫描线多边形填充算法,该算法可以有效地解决任意间距、任意倾角的扫描线对多边形的填充问题。通用扫描线多边形算法采用了坐标变换、浮点数舍入策略等重要方法。顶点扫描线号是该算法中的核心概念。     

Convergence Results of One-Leg and Linear Multistep Methods for Multiply Stiff Singular Perturbation Problems

One-leg methods and linear multistep methods are two class of important numerical methods applied to stiff initial value problems of ordinary differential equations. The purpose of this paper is to present some convergence results of A-stable one-leg and linear multistep methods for one-parameter multiply stiff singular perturbation problems and their corresponding reduced problems which are a class of stiff differential-algebraic equations. Received April 14, 2000; revised June 30, 2000     

Illness and injury in family day care: a seasonal survey

Many mothers with children under age 6 are employed and it is not usually feasible for a parent to stay home with a child who is mildly ill. Such ill children likely remain in child day care programs. The extent to which this occurs and the management of these children in family day care was studied. Over the course of a year, 1 to 3 visits were made to 714 family day care homes in order to survey providers. With enrollments ranging between 0 and 18 children per day care home at the time of each visit, information on 3,630 "child enrollment days" was collected. The median age of children in care was 2 years. An average of 16% of all children were ill on any one day (with seasonal variation); 1% were injured. Of ill children, 82% attended day care that day, 49% had contacted a physician about that illness, and 28% were administered a medication at the day care setting. Twenty-one percent of children receiving medication in day care had no contact with a physician for that illness. These data show that mild childhood illnesses are routinely managed by child day care providers. Physicians who traditionally limit their illness-management education to parents need to recognize the health education and consultation needs of day care providers.     

操作参数对玻纤毡增强复合材料流动成型的影响

研究了玻纤毡增强热塑性复合材料(GMT)流动成型过程中模腔压力和材料流动方向对制品力学性能和纤维取向的影响。研究表明：随着压力提高，弯曲强度和模量同步增加；但压力超过18MPa后，性能变化不明显。随布料面积分数减小，单轴拉伸流动成型将导致沿流动方向和垂直流动方向强度及模量差异变大，纤维取向严重；但双轴拉伸流动成型得到的制品各方向性能较均匀，基本呈现各向同性。     

碳纤维／铜—5%锡基复合材料的弯曲性能

测定了具有不同碳纤维的短碳纤维增强铜-5％锡基复合材料的弯曲强度值,实验表明:随碳纤维体积含量的增大,弯曲强度上升,并近似符合σ=94.5-421V_f+1557V_f~2(MPa)拟合式。与粉末治金铁基摩擦材料的弯曲性能对比表明:复合材料的弯曲性能较好。对碳/铜复合材料的弯曲断口作了扫描电镜观察,断口呈“部分拔出型”。最后,结合弯曲强度实验结果及断口观察,初步分析了该复合材料的断裂过程。     

新疆奎屯河洪水特征和最大值研究

洪水极易造成各种灾害,对当地经济发展影响巨大,通过对奎屯河洪水特征分析研究,揭示奎屯河洪水和最大值规律,以便制定措施治害兴利,为防洪和工程管理及当地经济发展提供科学依据。     

Acoustic emission generated during the gas sorption–desorption process in coal

An experimental system for monitoring the acoustic signals generated in coal during gas sorption and/or desorption was designed and the acoustic signals were observed under different gas pressures. The experimental results show that signals generated by the coal during gas adsorption are attenuated over time. Also, the signals are not continuous but are impulsive. The intensity of the signals generated during gas desorption is far smaller than that observed during adsorption. The signal seen during desorption remains essentially stable. Cycles of sorption and desorption cause acoustic emission signals that exhibit a memory effect, which depends upon the maximum gas pressure the sample was exposed to in earlier cycles. Lower pressures in subsequent cycles, compared to the maximum adsorption pressure in previous cycles, cause both the energy and impulse frequency to be lower than previously. On the contrary, a gas adsorption pressure that exceeds the maximum pressure seen by the sample during earlier cycles causes both the energy and impulse frequency to be high.     

精馏系统的虚拟装配技术研究

将虚拟装配技术引入化工流程中,对可视化设计化工流程、培训工人操作技能以及化工厂的数字化建设具有很大的应用价值。通过分析精馏系统,搭建了可视化装配平台。根据装配约束条件建立了可装配设备模型。提出了"1+1"和"1+n"普遍化的装配方法,实现了装配复杂精馏系统。通过输出装配信息,获取精馏系统装配过程中的装配方式和装配序列,验证装配操作的正确性。装配测试表明装配方法正确可行,其真实性、准确性和有效性满足了精馏系统虚拟装配的要求,实现了自由选择设备装配所需的精馏系统。系统可扩展性强,通过添加其它单元设备,可以实现所有化工流程的虚拟装配。