SiC/SiC mini-composites with multilayer ZrSiO4 interphase: Room-temperature properties and toughening mechanism

SiC/SiC mini-composites reinforced with SiC fibers coated with different numbers of ZrSiO₄ sublayers prepared via a non-hydrolytic sol-gel process were fabricated. The tensile strength and work of fracture of the prepared SiC/SiC mini-composites were determined, and the relationship between their mechanical properties and fracture morphologies was discussed. The toughening mechanism and the variation tendency of their mechanical properties were further elaborated by analyzing the interfacial debonding morphologies of the SiC/SiC mini-composites with 1 and 4 layers of ZrSiO₄ interphase as well as the results of prior studies. A relatively rare phenomenon—the delamination of the multilayer ZrSiO₄ interphase in the SiC/SiC mini-composites but not on the SiC fibers—was observed, which clearly demonstrated the weak bonding between the ZrSiO₄ sublayers in the SiC/SiC mini-composites. The ZrSiO₄ sublayer delamination mechanism was then explained based on the high-magnification morphologies found in and beside the ZrSiO₄ interphase.     

高光谱成像用高帧频CMOS图像传感器北大核心

针对高帧频、全局曝光和光谱平坦等成像应用需求,设计了一款高光谱成像用CMOS图像传感器。其光敏元采用PN型光电二极管,读出电路采用5T像素结构。采用列读出电路以及高速多通道模拟信号并行读出的设计方案来获得低像素固定图像噪声(FPN)和非均匀性抑制。芯片采用ASMC 0.35μm三层金属两层多晶硅标准CMOS工艺流片,为了抑制光电二极管的光谱干涉效应,后续进行了光谱平坦化VAE特殊工艺,并对器件的光电性能进行了测试评估。电路测试结果符合理论设计预期,成像效果良好,像素具备积分可调和全局快门功能,最终实现的像素规模为512×256,像元尺寸为30μm×30μm,最大满阱电子为400 ke^(-),FPN小于0.2%,动态范围为72 dB,帧频为450 f/s,相邻10 nm波段范围内量子效率相差小于10%,可满足高光谱成像系统对CMOS成像器件的要求。     

火花放电原子发射光谱类型标准化校正方式的探讨

在国内,火花放电原子发射光谱分析广泛使用类型标准化进行方法校正。在国外,标准和文献中鲜见使用此方法的相关论述。类型标准化主要采用平移校正和转动校正两种方式,哪种方式更加合理也鲜见报道。国外设备类型标准化的默认设置优先采用转动校正方式,相关国内标准对最优校正方式的规定尚不明确,此默认设置的合理性有待探讨。实验选用低合金钢20CrNi2Mo、R407标准样品和不锈钢317L、0Cr18Ni9标准样品,引用国内相关标准,以正确度临界差为评判依据,模拟类型标准化样品和待测样品“十分接近”和“接近”两种情况下平移校正和转动校正的数据正确度。经数据统计分析,平移校正分析结果均满足要求,转动校正结果在“接近”情况下部分元素不满足要求。结合相关国家标准中元素含量范围和精密度数据进行分析,通过计算允许最大偏倚量并制作曲线图方式展开分析,得出如下结论:在满足文中类型标准化控制要点前提下,分析设置更适合于采用平移校正方式。     

稳产国Ⅵ柴油并兼产喷气燃料技术方案的工业应用

介绍了浙江石油化工有限公司新建的3 Mt/a柴油加氢精制装置，其配套使用中国石化石油化工科学研究院有限公司开发的催化剂级配技术，并实施了可根据原料供应及市场产品需求情况灵活调整切换的2种生产技术方案。1 a的安稳生产运行结果表明:该装置以直馏柴油为主原料，通过分馏塔的馏分切割及其侧线抽出，实现了稳产国Ⅵ柴油并兼产喷气燃料技术方案的工业化应用；在实施以兼产喷气燃料为主的生产技术方案时，通过调整常一线柴油的掺炼量，不仅可以生产含硫量小于10.0 μg/g的精制柴油产品，同时兼产所得到的喷气燃料产品含硫量小于0.5 μg/g，赛波特颜色号值大于30；在实施主产精制柴油组分方案时，通过掺炼质量分数为20%~40%的催化柴油，并使所提炼得到的精制柴油组分含硫量小于6.0 μg/g的前提下，这些精制柴油组分产品既可直接作为满足国Ⅵ柴油产品出厂待售，也可作为柴油调和组分储存待用于产品的进一步优化。     

Analytical Modeling for Translating Statistical Changes to Circuit Variability by Ultra-Deep Submicron Digital Circuit Design

This paper presents a physics-based compact gate delay model that includes all short-channel phenomena prevalent at the ultra-deep submicron technology node of 32 nm. To simplify calculations, the proposed model is connected to a compact α-power law-based (Sakurai-Newton) model. The model has been tested on a wide range of supply voltages. The model accurately predicts nominal delays and the delays under process variations. It has been shown that at lower technology nodes, the delay is more sensitive to threshold voltage variations, specifically at the sub-threshold operating region as compared with effective channel length variations above the threshold region.     

Photoluminescence and energy transfer of Lu3Al5O12:Ce3+, Pr3+ phosphors

Ce³⁺ and Pr³⁺ co?doped Lu₃Al₅O₁₂ phosphors were synthesized by the sol–gel process, and their crystal structure, photoluminescence (PL) properties, and energy transfer (ET) from the Ce³⁺ to Pr³⁺ were studied. The Lu_2.94?yAl₅O₁₂:0.06Ce³⁺, yPr³⁺ phosphors (0.002 ≤ y ≤ 0.008) showed the green?yellow emission from the ²D_3/2 → ²F_{5/2, 7/2} transition of Ce³⁺ and the red emission at 610 and 637 nm, which were caused by the ¹D₂→³H₄ and ³P₀→³H₅ transitions of Pr³⁺, respectively. The optimal concentration of Pr³⁺ for efficient ET was found to be x = 0.006. The electric quadrupole?quadrupole interaction was responsible for the concentration quenching in the Lu_2.94?yAl₅O₁₂:0.06Ce³⁺, yPr³⁺ phosphors, based on Dexter's theory. The incorporation of Pr³⁺ for Lu³⁺ enhanced the red PL intensity in the Lu_2.94Al₅O₁₂:0.06Ce³⁺ phosphor.     

Sizing of multi-stage Op Amps by combining design equations with the gm/ID method

Analog integrated circuit design has as integral parts both analytical reasoning and numerical validation in the process from topology construction to sizing. Given a circuit topology, different circuit sizing results can be obtained from different processes of sizing inference. Sizing methods by simulation-based numerical searching have been a continuously studied subject. However, almost all approaches in this category require an overwhelming number of circuit simulations to arrive at an optimized sizing result. On the other hand, many published manual sizing methods by using the conventional device equations also require repeated SPICE simulations to correct the equation-based sizing results. This paper proposes a systematic gm/ID-based initial sizing method specifically customized for designing multiple-stage operational amplifiers (Op Amps). A main feature of the proposal is to use circuit-level design equations as constraints on the gm/ID table lookup method to substantially reduce the uncertainty in the sizing calculations. As a result, a significant amount of SPICE based correction work can be reduced to complete an initial sizing. The proposed sizing procedure includes a few regular sizing rules customized to the configuration of multi-stage Op Amps. We validate the proposed sizing method by application to several multi-stage Op Amp examples with a capacitive load or Miller compensation. Simulations have justified that the produced initial sizing results can achieve most of the prespecified design targets.     

我国鲜食玉米标准体系及营养标准研究

近年来我国鲜食玉米产业发展迅猛, 但同时也暴露出诸多产业乱象。梳理现有鲜食玉米标准体系是促进产业标准化、规范化的重要举措。本文通过对我国现行鲜食玉米标准进行梳理, 总结出目前我国鲜食玉米标准体系中抽样及一般性检测标准较完善、技术规程体系成熟、标准体系框架已建立的特点; 同时提出我国鲜食玉米标准体系存在技术规程标准内容重复、品质分级标准混乱、缺乏营养评价指标相关标准、感官评价标准混乱、缺乏甜糯玉米和笋玉米的相关标准、标准体系结构不合理等的问题; 并针对上述问题提出对应应统一技术规程标准, 建立营养评价体系, 统一品质分级标准, 统一感官评价指标, 完善甜糯玉米和笋玉米相关标准的解决办法。为鲜食玉米标准体系的建设及规范化提供参考和建议。     

Microstructure and mechanical properties of B4C matrix composites prepared via hot-pressing sintering with Pr6O11 as additive

High-performance B₄C-PrB₆ composites were prepared via hot-pressing sintering with matrix phase B₄C and with 2–5 wt% Pr₆O₁₁ as additive. The effects of different sintering processes and Pr₆O₁₁ content on the microstructure and mechanical properties of the composites were studied in detail. It is found that increasing sintering temperature and pressure will contribute to the densification of B₄C-PrB₆ composites. Coarse grains are formed in B₄C without additives at high temperature conditions, resulting in the decrease of the densification. Pr₆O₁₁ can effectively hinder the formation of coarse grains and finally promote the densification of the composites. The main toughening mechanisms of composites was crack deflection. The composites with 4 wt% Pr₆O₁₁ prepared at 2050 °C and 25 MPa had the best comprehensive mechanical properties. The relative density, hardness, flexural strength and fracture toughness reached to 98.9%, 37.6 GPa, 339 MPa and 4.4 MP am^1/2, respectively.