基于奇异值分解估计点扩散函数的复原算法研究

基于奇异值分解的性质,从离散退化模型出发,采用理想图像奇异值向量的平均能谱理论,得出用奇异值分解来估计点扩散函数的方法,复原过程用逆滤波法来实现。文中采用奇异值累计和函数的二阶导来确定点扩散函数估计过程中的重组阶数R1,三阶导曲线用于去噪的重组阶数R2的选取。用本文方法进行去噪复原实验,与自动选取法进行比较,去噪复原效果较好。     

Evaluation of metal-doped manganese oxide octahedral molecular sieves in catalytic reduction of NOx from cigarette mainstream smoke

A series of Ag, Cu and Co-doped manganese oxide octahedral molecular sieves (OMS-2) were synthesized and evaluated to remove nitrogen oxides (NO _x ) from cigarette mainstream smoke. The three kinds of catalysts were added to cigarettes for studying the capabilities of reducing NO _x from cigarette mainstream smoke. The catalysis and reduction of NO in laboratory were studied. A mechanism for NO _x catalytic reduction from burning cigarettes with the catalysts adding to cigarettes was described. The catalysts show excellent catalytic activity for NO _x removal, especially the Ag-doped OMS-2 catalyst. 0.5% (mass fraction) Ag-doped OMS-2 catalyst has the best ability to remove NO _x from cigarette mainstream smoke. The use of Ag-doped OMS-2 as catalyst for removing carcinogenic compounds from cigarette smoke will be an effective strategy to protect the environment and public health.     

某商铺火灾热和烟气危害性数值研究

为了研究商铺火灾中热和烟气对人体的危害,以实际火灾案例为背景,采用大涡模拟方法对起火店面进行数值重构,再现火灾过程.通过与燃烧现场取证及逃生人员的描述比较,计算结果很好地预测了火灾发展过程.探讨了高温、低氧以及一氧化碳和二氧化碳气体对人体的危害,通过构建人体模型研究热通量对人体的影响,并引入危害性指数这一概念,综合温度/浓度和作用时间两方面因素分析各参量的危害性大小,确定了人员致死原因.研究表明:燃烧造成室内一氧化碳和二氧化碳含量升高,但未达到短时间致死浓度,其危害性指数远小于1,可以认为是安全的.温度危害性指数最高,氧气次之,高温和过低的氧浓度是造成人员死亡的主要原因,这一结论与法医鉴定结果一致.     

BER Performance of Soft Decision Modulations Based on PCSS System

Recently, soft decision modulations become the highlight of parallel combinatory spread spectrum (PCSS) system. Existing soft decision BPSK and APK modulations are given and compared in the thesis. In order to apply soft decision QPSK modulation based on PCSS system, the correlation of superposition PN sequences is discussed. A weighted summation algorithm is adopted in QPSK demodulation to recover the whole orthogonal correlation of the superposition sequences; meanwhile the bit error rate of weighting soft decision QPSK modulation is simulated. The simulation results show that the bit error rate performance of proposed soft decision QPSK modulation based on PCSS system is better than that of hard decision modulation. The method proposed can be widely adopted in engineering application.     

改进的倾斜刃边法获取边缘扩展函数

在倾斜刃边法的基础上提出了一种改进的用于获取边缘扩展函数的方法。该方法采用改进的Hough变换获取目标边缘的倾斜角度,用几何投影的思路来获取边缘扩展函数的数据,用5点滤波平滑处理得到了最终的边缘扩展函数。实验通过对理想倾斜刃边图像创建人工模糊,对模糊化后的图像分别用改进的Hought变换和直线拟合计算倾斜角度,并将结果进行对比,验证了该方法的准确性和快速性;再将得到的边缘扩展函数数据用于计算MTF值并与理论值进行对比,验证了本方法获取边缘扩展函数数据的准确性。     

Normal-distribution-test algorithm for range spread target detection

A range spread target detection algorithm based on the normal distribution test is proposed. Based on the fact that the range spread target signal generally does not follow normal distribution, the range spread target detection problem is equivalent to the normal distribution test problem. Analysis show that the normal distribution test detector has the characteristic of constant false alarm rate. The performance of the proposed detector is analyzed. Numerical experimental results based on simulation and measured high range resolution profile data show that the proposed detector outperform the energy integration detector.     

基于扩散分析的网络安全威胁态势评估

针对多数态势评估方法欠缺对授权与依赖关系的考虑、无法反映间接威胁、评估结果对动态防御的指导作用不大的问题,提出了一种以威胁扩散分析为基础、以攻击意图揣测为延伸的评估方法。首先评估了攻击施加的直接威胁,及其沿着依赖关系扩散引发的间接威胁。然后探讨了多攻击并发时的非线性叠加效应。最后使用覆盖法和聚类法揣测攻击意图。实验表明,该方法能更透彻、更精准地揭示安全状况,较好地指导动态防御。     

中国化马克思主义在大学生中的传播研究

在传播机制下探讨当代中国化马克思主义在大学生传播过程中遭遇的困境并进行路径探索是一个新颖的方向。分析当代中国化马克思主义在大学生传播过程中遭遇的现实困境。当前影响中国化马克思主义在大学生中传播的具体原因。得出,要切实增强中国化马克思主义在大学生中的传播效果,提高其影响力,就必须要构建科学的传播体系。通过整合各种传播途径,创新传播方法,提高传播效果;通过建立科学、合理、可行的传播效果评估体系与调适机制,不断完善中国化马克思主义的传播机制。     

风环境下烟雾的实时模拟

在复杂环境仿真中,烟雾的模拟具有重要的意义.提出一种基于流体力学方程的烟雾模拟方法,并实现了脉动风与烟雾的交互,使烟雾的形态和运动更加逼真自然.采用简化的Von Karman模型建立风场,并引入特征正交分解技术(POD)和快速傅立叶变换技术(FFT)简化其建立过程.利用非粘性不可压缩的N-S(Navier-Stokes)方程描述烟雾运动,并将风场的作用加入到N-S方程中,利用破开算子法和MacCormack法简化N-S方程的求解过程,减少计算量,并保证求解过程在大的时间步长上的稳定性.同时,引入了"漩涡限制",将数值求解过程中的插值耗散补充回流场,增强烟雾的真实性.实验证明,利用本文的方法能够实时高效的模拟出自然逼真三维烟雾效果.