2.3–21 GHz broadband and high linearity distributed low noise amplifier

This paper focuses on the design of a 2.3–21 GHz Distributed Low Noise Amplifier (LNA) with low noise figure (NF), high gain (S₂₁), and high linearity (IIP3) for broadband applications. This distributed amplifier (DA) includes S/C/X/Ku/K-band, which makes it very suitable for heterodyne receivers. The proposed DA uses a 0.18 μm GaAs pHEMT process (OMMIC ED02AH) in cascade architecture with lines adaptation and equalization of phase velocity techniques, to absorb their parasitic capacitances into the gate and drain transmission lines in order to achieve wide bandwidth and to enhance gain and linearity. The proposed broadband DA achieved an excellent gain in the flatness of 13.5 ± 0.2 dB, a low noise figure of 3.44 ± 1.12 dB, and a small group delay variation of ±19.721 ps over the range of 2.3–21 GHz. The input and output reflection coefficients S₁₁ and S₂₂ are less than −10 dB. The input compression point (P_1dB) and input third-order intercept point (IIP3) are −1.5 dBm and 11.5 dBm, respectively at 13 GHz. The dissipated power is 282 mW and the core layout size is 2.2 × 0.8 mm².     

Propagation and termination of an internal crack in continuously cast austenitic stainless steel analyzed by ∑ values and the Schmid factor

The formation mechanism of an internal crack was clarified from the viewpoint of the crystallography and thermal expansion. An inverse pole figure map obtained by EBSD pattern showed that the crack propagated along the grain boundaries having high ∑ values within the columnar zone. After the crack initiation, these positions were considered to undergo cracking followed by propagation toward the equiaxed side. Near the termination position, the grains ahead of crack propagation had a Schmid factor higher than 0.45 consuming elastic strain energy. Thermal expansion measurements showed that the grain with (0 0 1) orientation had the largest expansion while that with (0 1 1) the smallest. The grain boundaries neighboring the combination of (0 0 1) and (0 1 1) grains had the largest thermal stress. Therefore, thermal stress contributed to the initiation of cracking. It was thus proposed to enlarge the equiaxed zone to prevent cracking by discontinuing the crack propagation.     

基于深度学习的秀丽隐杆线虫显微图像分割方法

利用计算机实现自动、准确的秀丽隐杆线虫(C.elegans)的各项形态学参数分析,至关重要的是从显微图像上分割出线虫体态,但由于显微镜下的图像噪声较多,线虫边缘像素与周围环境相似,而且线虫的体态具有鞭毛和其他附着物需要分离,多方面因素导致设计一个鲁棒性的C.elegans分割算法仍然面临着挑战。针对这些问题,提出了一种基于深度学习的线虫分割方法,通过训练掩模区域卷积神经网络(Mask R-CNN)学习线虫形态特征实现自动分割。首先,通过改进多级特征池化将高级语义特征与低级边缘特征融合,结合大幅度软最大损失(LMSL)损失算法改进损失计算;然后,改进非极大值抑制;最后,引入全连接融合分支等方法对分割结果进行进一步优化。实验结果表明,相比原始的Mask R-CNN,该方法平均精确率(AP)提升了4.3个百分点,平均交并比(mIOU)提升了4个百分点。表明所提出的深度学习分割方法能够有效提高分割准确率,在显微图像中更加精确地分割出线虫体。     

Role of cube texture on toughness variation of electric resistance welded steel

Properties changes of an X52 microalloyed steel processed by a full-scale industrial electric resistant welding (ERW) equipment was studied. Lack of proper toughness level in the weld zone was investigated. Results show that the low toughness value could only be satisfactorily addressed after a two-stage annealing process. {100} pole figures for each processing step revealed a completely random texture for the initial plate. However, after the ERW process, a textured structure with the main components of brass, S and copper was obtained. Texture components were substantially weakened after the second stage of annealing and instead a cube texture was developed which could explain satisfactory level of toughness for the ERW pipe after conducting the two-step annealing process.     

船屋文化：海南黎族传统民居探源

从文化心理行为模式的角度对黎族民居空间及造型形成过程进行了探讨。认为人类在塑造自己生存立足的场所时一直伴随着对意义的追求，人赋予建筑的表征意义在很大程度上决定了建筑空间及造型的可识别性特性，构成了场所感，成为特定地域、特定场所的一种文化“原型”识别性标志。     

"建构学的哲学"解读

文章从四个方面解读了席沃扎博士的论文“建构学的哲学”:作者的学术背景和相关著述;建构学的兴起;德国建筑理论中的“建构学”;从建筑的“现代性”来分析现代建筑时期的建构学、当代建构学和作者提出的“镜头景观”。     

天空亮度分布用图像数字化系统再现及处理新技术

介绍了一种计算机处理天空亮度分布图象数字化再现技术。应用该计算处理程序可以十分方便而准确地数字化再现天空亮度分布，从而能更准确可靠的研究天空亮度分布。     

小议工程量清单计价

浅析了实行工程量清单计价招投标的重要意义,介绍了工程量清单招标的具体操作,并对实施工程量清单招投标的环境条件进行了阐述,以进一步完善工程量清单计价体制。     

圆柱形锂离子电池的电芯轮廓特性研究——基于Matlab驱动的工艺间隙求解程序

卷绕式锂离子电池的制作原理导致电芯与外壳的间隙只能用矢量进行描述。以往对这个概念模糊化处理带来了一系列问题。例如,设计中指标最优化、工艺中过程控制参数、制作中装配效果量化、软件编写中多变量制约与取舍……以某电芯轮廓为研究对象,借助Matlab开发了代码,通过提出假设和原则将问题简单化后,模拟了间隙分布,并得到某些参数与其的作用关系,为解决以上问题提供了理论支撑,具有初步指导意义。     

A UWB CMOS low-noise amplifier with noise reduction and linearity improvement techniques

In this paper, a highly linear CMOS low noise amplifier (LNA) for ultra-wideband applications is presented. The proposed LNA improves both input second- and third-order intercept points (IIP2 and IIP3) by canceling the common-mode part of all intermodulation components from the output current. The proposed LNA structure creates equal common-mode currents with the opposite sign by cascading two differential pairs with a cross-connected output. These currents eliminate each other at the output and improve the linearity. Also, the proposed LNA improves the noise performance by canceling the thermal noise of the input and auxiliary transistors at the output. Detailed analysis is provided to show the effectiveness of the proposed LNA structure. Post-layout circuit level simulation results using a 90 nm RF CMOS process with Spectre-RF reveal 9.5 dB power gain, -3 dB bandwidth (BW_−3dB) of 8 GHz from 2.4 GHz to 10.4 GHz, and mean IIP3 and IIP2 of +13.1 dBm and +42.8 dBm, respectively. The simulated S₁₁ is less than −11 dB in whole frequency range while the LNA consumes 14.8 mW from a single 1.2 V power supply.