傅立叶变换在虚拟仪器LabVIE中的应用

文中介绍了LabVIEW环境下用NI公司高级分析库里的信号处理工具包的Real FFT.vi傅立叶变换,采用此种方法对某型飞机起落架液压测试系统采样信号进行频谱分析,实验证明其效果良好.     

Monolithic SiGe Up‐/Down‐Conversion Mixers with Active Baluns

The purpose of this paper is to describe the implementation of monolithically matching circuits, interface circuits, and RF core circuits to the same substrate. We designed and fabricated on‐chip 1 to 6 GHz up‐conversion and 1 to 8 GHz down‐conversion mixers using a 0.8 µm SiGe hetero‐junction bipolar transistor (HBT) process technology. To fabricate a SiGe HBT, we used a reduced pressure chemical vapor deposition (RPCVD) system to grow a base epitaxial layer, and we adopted local oxidation of silicon (LOCOS) isolation to separate the device terminals. An up‐conversion mixer was implemented on‐chip using an intermediate frequency (IF) matching circuit, local oscillator (LO)/radio frequency (RF) wideband matching circuits, LO/IF input balun circuits, and an RF output balun circuit. The measured results of the fabricated up‐conversion mixer show a positive power conversion gain from 1 to 6 GHz and a bandwidth of about 4.5 GHz. Also, the down‐conversion mixer was implemented on‐chip using LO/RF wideband matching circuits, LO/RF input balun circuits, and an IF output balun circuit. The measured results of the fabricated down‐conversion mixer show a positive power conversion gain from 1 to 8 GHz and a bandwidth of about 4.5 GHz.     

Computational Implementation of Asymmetric Integral Imaging by Use of Two Crossed Lenticular Sheets

We propose an asymmetric integral imaging method to adjust the resolution and depth of a three‐dimensional image. Our method is obtained by use of two lenticular sheets with different pitches fabricated under the same F/#. The asymmetric integral imaging is the generalized version of integral imaging, including both conventional integral imaging and one‐dimensional integral imaging. We present experimental results to test and verify the performance of our method computationally.     

Reversible watermarking scheme with image-independent embedding capacity

Permanent distortion is one of the main drawbacks of all the irreversible watermarking schemes. Attempts to recover the original signal after the signal passes the authentication process are being made, starting just a few years ago. Some common problems, such as salt-and-pepper artefacts owing to intensity wraparound and low embedding capacity, can now be resolved. However, some significant problems remain unsolved. First, the embedding capacity is signal-dependent, i.e., capacity varies significantly depending on the nature of the host signal. The direct impact of this is compromised security for signals with low capacity. Some signals may be even non-embeddable. Secondly, while seriously tackled in irreversible watermarking schemes, the well-known problem of block-wise dependence, which opens a security gap for the vector quantisation attack and transplantation attack, are not addressed by researchers of the reversible schemes. This work proposes a reversible watermarking scheme with near-constant signal-independent embedding capacity and immunity to the vector quantisation attack and transplantation attack.     

A Silicon–Silica Nanocomposite Material

The synthesis and characterization of a novel silicon–silica nanocomposite material are reported. A self‐assembly method allows the encapsulation of silicon nanoclusters within the channels of a periodic mesoporous silica thin film. The result is the formation of a silicon–silica nanocomposite film with bright, room‐temperature photoluminescence in the visible range, and a nanosecond luminescence lifetime. The properties of the nanocomposite material have been studied by several analytical techniques, which collectively show the existence within the channels of non‐diamondoid‐structure‐type silicon nanoclusters with various hydrogenated silicon sites. It is estimated that the silicon nanoclusters in the silica mesoporous films occupy up to 39 % of the accessible pore volume. The nanocomposite film shows improved resistance to air oxidation compared to crystalline silicon. The high loading and chemical stability to oxidation under ambient conditions are important advantages in terms of the development of silicon‐based light‐emitting diodes from this class of materials.     

Synthesis of Nearly Monodisperse Iron Oxide and Oxyhydroxide Nanocrystals

Uniform magnetite, hematite, and goethite nanocrystals were prepared through an attractive method based on an oleic acid/alcohol/water system. By adjusting the synthetic parameters (base concentration, alcohol content, categories of alcohols, etc.), the controlled synthesis of uniform magnetite, hematite, and goethite nanocrystals can be easily achieved. Detailed investigations on the effect of the experimental parameters on the morphology of the final products and the phase transitions among the magnetite, hematite, and goethite phases were carried out. Finally, a method of doping other metal ions into magnetite was developed and the magnetic properties of magnetite doped with different metal elements were studied.     

Induction of immune tolerance with heart-thymus composite allotransplantation in rats

Objective To study on the role of thymus transplantation for heart allograft in rats. Methods Vascularized heart-thymus combined transplantation was performed with microsurgical technique. Graft survival, histopathology, level of IL-2, IL-4 and its mRNA expression in serum and cardiac grafts were investigated. Results Heart-thymus combined transplantation achieved effect in the prolongation of cardiac graft survival with short-term administration of cyclosporine. Conclusions Vascularized thymus transplantation induced immune tolerance in thymectomized rats.     

一种新型悬臂棒条筛的设计与应用

介绍了一种新型悬臂棒条筛分机械,论述了其结构、工作原理和技术特性。从理论和实践两方面论证了它的结构、处理能力、筛分效率、返矿率都明显优于普通悬臂棒条筛分机械,可广泛应用于高炉槽下烧结矿的筛分作业。     

小水电工业电视监控系统的应用现状与发展

对小型水电站现今应用的简单的现场图像监视系统和最新发展的基于局域网的全数字工业图像监控系统进行解释和分析，探讨小型水电站工业电视监控系统的发展趋势。图2幅，表1个。