A high resolution approach for nonlinear sub-harmonic imaging

Nonlinear sub-harmonic phased array imaging is used to visualize closed cracks. Sub-harmonic imaging has broader beam width than that of input frequency imaging due to its longer wavelength. If the broad beam width results in low image resolution, it can be hard to determine the locations of cracks. Various methods have been developed to enhance the resolution, and MUltiple SIgnal Classification (MUSIC), in particular, is an old but well-established way to do so. A form of sub-harmonic imaging that implements MUSIC is presented here. A numerical simulation was used to compare the proposed method with a conventional one, and MUSIC gave narrower beam width. Experiments also demonstrated that MUSIC could improve the resolution of sub-harmonic imaging.     

To reduce side lobe level of slotted array antennas using nonuniform waveguides

In this article, a method is presented to reduce the side lobe level of slotted waveguide array antennas while the gain to be constant. In this method, the H‐plane dimension of the waveguide is considered as the variable rather than constant. The nonuniformity of waveguide walls obviates the need for offset of slots and thereby reduces the side lobe level of radiation pattern. A slotted nonuniform waveguide is designed at frequency 10 GHz and then fabricated and tested. © 2015 The Authors International Journal of RF and Microwave Computer‐Aided Engineering Published by Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:42–46, 2016.     

Highly efficient VLSI architecture for DWT with low-storage implementation

With the gradual increase in image resolution of the spacecraft camera, it is highly required to figure out the problem how to process a huge amount of image data on board at a high speed. As a solution, the CCSDS proposes a space-oriented image-coding standard. For the sake of high image-coding performance, it adopts wavelet transformation as a method of image data transformation. However, wavelet transformation contains multi-level data processing, which causes more computational time consumption and more memory utilization. In order to solve this problem, we propose a highly efficient VLSI architecture for DWT with low-storage. By revising the traditional lifting structure and employing time-multiplex data processing strategy to perform the second and third level of wavelet transformation by the same logic module, the usage of logic resource is reduced with no sacrifice on speed.Using a small amount of on-chip memory instead of off-chip memory to save certain parts of DWT coefficients and sending the coefficients in a specific sequence to entropy coder timely, the off-chip memory for storage of DWT coefficients is no longer required. The proposed VLSI architecture of DWT is already implemented on the Xilinx FPGA XC4VSX55, which can achieve a high performance, in terms of data throughput, reaching 95.91MPixels/s.     

Realization of active power filter based on indirect current control algorithm using Xilinx system generator for harmonic elimination

Realization of active power filter with Model Based Design approach is presented in this paper. The approach adopts different modeling platforms as well as selection of proper hardware for step wise verification and testing. The active power filter model is developed using the Matlab/Simulink platform for single phase. The efficiency of the control algorithms such as synchronous detection method and indirect current control for active power filter is analyzed. Efficient control algorithm is developed by Xilinx system generator which is incorporated into Simulink as Xilinx tool box. Xilinx system generator provides a virtual platform for easy and effective design of the required system models in FPGA (field programmable gate array) design environments. Optimized automatic VHDL code is generated for the control algorithm which is simulated using ISE 13.2 for the generation of switching signals for the control of IGBTs of the active power filter. Suitable compensation signal is generated from the active power filter for the better elimination harmonics to improve the power quality. THD is reduced to a considered value which is able to satisfy the limits of the IEEE standard.     

The Bulk Production Of Colour Prints

Some indication of the use of Phenidone in PQ developer systems in large scale motion picture laboratory practice is given. Various characteristics, which were examined on a plant scale before MQ systems were abandoned in favour of PQ systems, are discussed; the stabilities and economics of the two systems are compared.     

3D geometry reconstruction from orthographic views: A method based on 3D image processing and data fitting

Industrial esthetic designers typically produce hand-drawn sketches in the form of orthographic projections. A subsequent translation from 2D-drawings to 3D-models is usually necessary. This involves a considerably time consuming process, so that some automation is advisable.     

小型静态CT用多焦点X射线源电子束偏转系统研究

第5代全静态电子束CT（EBCT）能在被检测物体、射线源和探测器均处于静止状态下完成CT扫描成像。这种EBCT成像方式既可应用于粉体材料、生物活体样品等易形变物体的CT检测，又可应用于物流包裹、在役管线等的快速CT检测。高精度的电子束偏转系统是静态CT成像多焦点射线源的关键技术之一。本文基于麦克斯韦电磁场相互作用理论，探讨了电子束在均匀磁场、小偏转角、近轴区域内的散焦、畸变及灵敏度特性，研究了影响电子束扫描系统焦点位置重复精度的物理参数及电子束在靶平面上的扫描偏转量与偏转线圈电流的线性关系。并设计、加工制作了一种小型高精度多焦点X射线的电子束偏转扫描系统，实验采用直径0.1 mm标准针规电子束扫描DR投影图像序列，验证了电子束偏转系统有良好的偏转线性，偏转量正比于O点的磁场强度，而与电子束的位置等初始条件无关。实验通过电子束偏转系统控制电子束偏转扫描，获得了熔断式保险管（Ø100 μm）的250个 X 射线视角投影，完成了第5代全静态三维CT重建图像。     

Imaging of Extracellular pH Using Hyperpolarized Molecules

Many diseases can overrule natural pH regulatory mechanisms and alter the extracellular pH (pH_e). A non-invasive method that resolves pH_e in vivo with high spatial and temporal resolution could therefore improve diagnosis and monitoring of diseases, contributing to the concept of precision medicine. During the last decades, several techniques have been proposed to image pH_e non-invasively. The majority of these methods rely on magnetic resonance because of its good spatial resolution, high penetration depth, non-ionizing radiation and excellent complimentary soft tissue contrast. Dissolution dynamic nuclear polarization (DNP) is an emerging concept to enhance nuclear magnetic resonance (NMR) signals by more than four orders of magnitude, making it possible to observe in vivo metabolic processes in real-time. Here, we summarize and review recent developments in pH_e imaging techniques based on hyperpolarization methods and give an overview of recently discovered hyperpolarized pH sensor molecules that have been applied in vitro and in vivo.