FPGA中低噪声CCD时序驱动电路设计

在分析Toshiba公司TCD1209D型CCD工作原理的基础上,分析了驱动时序的关系,详细介绍了驱动电路的设计和实现方法.用Verilog语言设计了TCD 1209D的驱动时序控制电路;选用CyclonelⅣ系列FPGA器件,使用QuartusⅡ软件对设计电路进行了功能仿真,实现了TCD1209D的高速时序驱动;在CycloneⅣ芯片平台上测试了TCD 1209D的实际输出信号.实验结果显示,CCD信号噪声较小,验证了所设计驱动电路的可行性,确定了相关双采样的时刻和位置,为小型CCD测量系统的设计提供了有益参考.     

Manifold Constrained Transfer of Facial Geometric Knowledge for 3D Caricature Reconstruction

3D caricatures are important attractive elements of the interface in virtual environment such as online game. However, very limited 3D caricatures exist in the real world. Meanwhile, creating 3D caricatures manually is rather costly, and even professional skills are needed. This paper proposes a novel and effective manifold transfer algorithm to reconstruct 3D caricatures according to their original 2D caricatures. We first manually create a small dataset with only 100 3D caricature models and use them to initialize the whole 3D dataset. After that, manifold transfer algorithm is carried out to refine the dataset. The algorithm comprises of two steps. The first is to perform manifold alignment between 2D and 3D caricatures to get a "standard" manifold map; the second is to reconstruct all the 3D caricatures based on the manifold map. The proposed approach utilizes and transfers knowledge of 2D caricatures to the target 3D caricatures well. Comparative experiments show that the approach reconstructs 3D caricatures more effectively and the results conform more to the styles of the original 2D caricatures than the Principal Components Analysis (PCA) based method.     

Reliable synthesis of bismuth nanoparticles for heavy metal detection

A reliable and facile pathway is described here for preparing high-quality bismuth nanoparticles. Combined with hydrothermal method and confined growing effect of polymer, bismuth nanoparticles with uniform size and shape were obtained with remarkable productivity. The nanoparticles is proved to be pure Rhombohedral structure Bi crystals with R-3m space group and the diameter of the nanoparticles is about 80 nm with a quite narrow particle size distribution. Those bismuth nanoparticles were predicted to grow from a rolling process by sheet-like Bi nanocrystal intermediates. The obtained bismuth nanoparticles were used to prepare modified electrode for the detection of Cd²⁺ and Pb²⁺ in water solution by stripping analysis. Compared with naked glassy carbon electrodes, the modified electrode showed two obvious responses at −0.85 V and −0.62 V, corresponding to the reduction process of Pb²⁺ and Cd²⁺ and this well-resolved stripping response can be observed when the concentration is as low as 10 μg/L, indicating potential application in electroanalysis for environmental inspection.     

Estimation of instantaneous local heat transfer coefficient in spark-ignition engines

Optimizing heat transfer for internal combustion engines requires application of advanced development tools. In addition to experimental method, numerical 3D-CFD calculations are needed in order to obtain an insight into the complex phenomenas in-cylinder processes. In this context, fluid flow and heat transfer inside a four-valve engine cylinder is modeled and effects of changing engine speed on dimensionless parameters, instantaneous local Nusselt number and Reynolds number near the surface of combustion chamber are studied. Based on the numerical simulation new correlations for instantaneous local heat transfer on the combustion chamber of SI engines are derived. Results for several engine speeds are compared for total heat transfer coefficient of the cylinder engine with available correlation proposed by experimental measurements and a close agreement is observed. It is found that the local value of heat transfer coefficient varies considerably in different parts of the cylinder, but it has equivalent trend with crank angle position.     

On the double-layer structure of the boundary layer adjacent to a sidewall of a differentially heated cavity

This study is concerned with the transition of the boundary layer adjacent to a sidewall of a differentially heated cavity to a double-layer structure and with the important flow and heat transfer features of the double-layer structure. The transition to the double-layer structure is examined by comparing numerical and experimental results. The mechanism responsible for the formation of the double-layer structure, i.e. the stratification of the fluid in the core, is discussed. Detailed discussion of the energy balance adjacent to the sidewall reveals that the heat transfer in the double-layer structure is rather complex. There is an opposing horizontal thermal diffusion within the double-layer structure.     

A comparative study on the tribological behaviors of nitrided and sulfur-nitrided 35CrMo steel lubricated in PAO base oil with MoDTC additive

A nitrided layer on 35CrMo steel was prepared by the ion nitriding process, and then a sulfur-nitrided layer was obtained by low temperature ion sulfuration. The results showed that both the nitrided and sulfur-nitrided surfaces improved the wear resistance efficiently under PAO lubrication, and exhibited the best wear resistance and friction-reducing property under PAO with 0.75% MoDTC lubrication. Compared with the plain and nitrided surfaces, the sulfur-nitrided surface exhibited the best synergistic effect with MoDTC displaying the lowest friction coefficient and wear volume. The mechanism of the best effect was due to MoS₂ and FeS formed on the sulfur-nitrided surface.     

身管弹膛和线膛同锻时下沉段皱褶试验研究及其预测

身管弹膛和线膛同锻技术可用径向精锻工艺同时锻出弹膛和线膛,将彻底解决身管弹膛和线膛的同轴度问题,改善坡膛部位的表面粗糙度。为提高身管内膛的加工质量,以身管弹膛和线膛同锻为对象,研究下沉段和锻造段产生的褶皱以及演变情况。通过对身管径向锻打试验和形貌试验分析处理,发现弹膛和线膛同锻时：下沉段将会产生褶皱,并且褶皱随着变形的增加,深度不断加深;当进入锻造段后,部分皱褶被打平,变成了身管微裂纹。应用有限元分析软件Abaqus对身管锻打过程进行仿真,发现锻打过程中下沉段径向应变ε_r和周向应变ε_θ的比值[SX(]ε_r[]ε_θ[SX)]为定值,不同锻打工艺参数下应变比值不同。研究结果表明：身管下沉段单次锻打产生的褶皱深度Δd_w可以用径向应变ε_r和周向应变ε_θ的比值[SX(]ε_r[]ε_θ[SX)]来表示,拟合的关系式为Δd_w=0.058 8[SX(]ε_r[]ε_θ[SX)]+0.052 1;结合锻打所需的锤数可以预测出下沉段结束位置的皱褶深度,皱褶深度的预测有助于防止褶皱在锻造段挤压形成锻造身管的微裂纹。     

光强正交调制型位移传感器的数学模型与误差分析

针对传统光学位移测量方法对环境要求高和制造精度难以提高等问题,提出了一种以交变光场为测量媒介的新型线性位移检测方法。基于提出的方法,设计了一种光强正交调制型位移传感器。该方法采用基于光强正交变化的两路电驻波合成电行波信号,通过对行波信号时间先后的测量实现空间位移的测量。为了深入理解传感器的传感机理,推导了传感器的测量模型,分析了与传感机理相关的关键因素对测量误差的影响。根据测量原理和测量模型的理论分析,研制出传感器原理样机,通过实验测试了各种关键因素对测量误差的影响,并进一步优化设计了传感器结构与参数。实验显示,优化后的传感器在108mm测量范围内的测量精度达到±0.5μm,是一种新的无需精细刻划的位移检测方案。     

5182铝合金表面锆化膜的制备及其性能研究

目的提高5182铝合金的耐蚀性能及与有机漆膜的结合力。方法采用氟锆酸试剂与5182铝合金反应制备锆化膜,探究锆化液pH值、浸泡时间对锆化膜耐蚀性能的影响,并优化制膜工艺。采用SEM、EDS能谱仪及超薄切片仪分析锆化膜的微观结构和成分,结合SKPFM分析合金中第二相颗粒的电位对锆化膜形成机理的影响,采用EIS对锆化膜的耐蚀性能进行评价分析,采用涂层附着力自动划痕仪评价锆化涂层对巴斯夫有机漆膜结合力的影响。结果制备锆化膜的最佳工艺为:pH=4.5,浸泡时间2.5 min。在5182铝合金表面制备了一层50～100 nm厚的锆化膜,且该锆化膜优先在阴极性的第二相颗粒上形成。EIS分析表明,在Na_2B_4O_7×10H_2O和NaOH水溶液中,锆化处理试样的低频阻抗值比未锆化处理试样高80?。划痕测试表明,锆化处理试样与未锆化处理试样相比,其临界载荷提高了75%。结论经过锆化最佳工艺处理后,5182铝合金的耐蚀性能提高,且锆化涂层作为中间层,能显著提高有机漆膜与合金基体的结合强度。