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Formation of hierarchical Si3N4 foams by protein-based gelcasting and chemical vapor infiltration

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Journal of Advanced Ceramics 2021年第1期10卷 187-193页

作者： Junsheng LI Qiuping YU Duan LI Liang ZENG shitao gao Science and Technology on Advanced Ceramic Fibers and Composites Laboratory College of Aerospace Science and EngineeringNational University of Defense TechnologyChangsha 410073China

Silicon nitride foams with a hierarchical porous structure was formed by the combination of protein-based gelcasting,chemical vapor infiltration,and in-situ growth of silicon nitride nanowires.The porosity of the foams can be controlled at 76.3-83.8 vol%with an open porosity of 70.2—82.8 vol%.The pore size distribution was presented in three levels:100μm(cells).The resulted compressive strength of the porous bodies at room temperature can achieve up to 18.0±1.0 MPa(porosity=76.3 vol%)while the corresponding retention rate at 800℃was 58.3%.Gas permeability value was measured to be 5.16(cm^(3)·cm)/(cm^(2)·s·kPa).The good strength,high permeability together with the pore structure in multiple scales enabled the foam materials for microparticle infiltration applications.

关键词： ceramics sintering porosity mechanical properties permeability

Preparation and interface modification of Si3N4f/SiO2 composites

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Journal of Materials Science & Technology 2019年第12期35卷 2767-2771页

作者： Yubo Houa Xuejin Yang Bin Li Duan Li shitao gao Zhongshuai Wu Science and Technology on Advanced Ceramic Fibers and Composites Laboratory National University of Defense TechnologyChangsha410073China School of Materials Sun Yat-sen UniversityGuangzhou510275China

In order to modify the interface, Si ON coating was introduced on the surface of silicon nitride fiber by perhydropolysilazane conversion method. Si-3N4f/SiO2 and Si-3N4f/Si ONc/SiO2 composites were prepared by sol-gel method to explore the influence of Si ON coating on the mechanical properties of composites.The results show that with the protection of Si ON coating, Si-3N4fiber enjoys a strength increase of up to 24.1% and Si-3N4f/Si ONc/SiO2 composites have a tensile strength of 170.5 MPa and a modulus of26.9 GPa, respectively. After 1000℃ annealing in air for 1 h, Si-3N4f/Si ONc/SiO2 composites retain 65.0%of their original strength and show a better toughness than Si-3N4f/SiO2 composites. The improvement of mechanical properties is attributing to the healing effect of Si ON coating as well as its intermediate coefficient of thermal expansion between Si-3N4fiber and SiO2 matrix.

关键词： Si3N4 fiber Perhydropolysilazane SiON coating Interface Mechanical properties

KD-S SiC_f/SiC composites with BN interface fabricated by polymer infiltration and pyrolysis process

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Journal of Advanced Ceramics 2018年第2期7卷 169-177页

作者： Honglei WANG shitao gao Shuming PENG Xingui ZHOU Haibin ZHANG Xiaosong ZHOU Bin Li Innovation Research Team for Advanced Ceramics Institute of Nuclear Physics and ChemistryChina Academy of Engineering Physics Science and Technology on Advanced Ceramic Fibers and Composites Laboratory National University of Defense Technology

Continuous silicon carbide fiber reinforced silicon carbide matrix(SiC_f/SiC) composites are attractive candidate materials for aerospace engine system and nuclear reactor system. In this paper, SiC_f/SiC composites were fabricated by polymer infiltration and pyrolysis(PIP) process using KD-S fiber as the reinforcement and the LPVCS as the precursor, while the BN interface layer was introduced by chemical vapor deposition(CVD) process using borazine as the single precursor. The effect of the BN interface layer on the structure and properties of the SiC_f/SiC composites was comprehensively investigated. The results showed that the BN interface layer significantly improved the mechanical properties of the KD-S SiC_f/SiC composites. The flexure strength and fracture toughness of the KD-S SiC_f/SiC composites were evidently improved from 314±44.8 to 818±39.6 MPa and 8.6± 0.5 to 23.0±2.2 MPa·m^(1/2), respectively. The observation of TEM analysis displayed a turbostratic structure of the CVD-BN interface layer that facilitated the improvement of the fracture toughness of the SiC_f/SiC composites. The thermal conductivity of KD-S SiC_f/SiC composites with BN interface layer was lower than that of KD-S SiC_f/SiC composites without BN interface layer, which could be attributed to the relative low thermal conductivity of BN interface layer with low crystallinity.

关键词： silicon carbide(SiC) composites interface layer polymer infiltration and pyrolysis(PIP) boron nitride(BN)

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基于子区间的雷达探测距离和测距精度分析

工程设计学报 2024年第3期31卷 332-339页

作者：欧阳衡高硕王世涛马正琰张德权河北工业大学机械工程学院天津300401 河北工业大学省部共建电工装备可靠性与智能化国家重点实验室天津300401 31002部队北京100094

探测距离和测距精度是雷达的关键性能指标,在实际服役工况下受雷达系统内部信号传输损耗、外部信号干扰等不确定性因素的影响较大,提高其准确性已成为雷达研究领域的重要课题。为了评估上述不确定性因素对雷达性能的影响程度,开展了雷... 详细信息

探测距离和测距精度是雷达的关键性能指标,在实际服役工况下受雷达系统内部信号传输损耗、外部信号干扰等不确定性因素的影响较大,提高其准确性已成为雷达研究领域的重要课题。为了评估上述不确定性因素对雷达性能的影响程度,开展了雷达探测距离和测距精度的不确定性分析。首先,建立了考虑信号传输损耗和信号干扰的雷达探测距离和测距精度模型;其次,采用区间模型量化不确定性参数,实现内外部参数统一框架下的不确定性度量;然后,构建准确的探测距离和测距精度响应面模型,并采用Sobol􀆳全局敏感性分析方法实现多维参数对探测距离和测距精度影响的排序;最后,采用子区间分解分析方法获取了雷达探测距离和测距精度区间,并与通过蒙特卡洛模拟得到的结果进行对比,验证所提方法的有效性。将雷达探测距离和测距精度设定合理的容限与阈值,可提高雷达性能分析效率,降低性能分析成本。

关键词：探测距离测距精度不确定性响应面子区间

Oxalic acid functionalization of BaTiO_(3) nanobelts for promoting their piezo-degradation organic contaminants

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Journal of Materiomics 2021年第6期7卷 1275-1283页

作者： shitao gao Hongjie Xing Jingji Zhang Yapi Liu Huiwei Du Zejie Zhu Jiangying Wang Xu Li Suwei Zhang Yaxuan Yao Lingling Ren College of Materials and Chemistry China Jiliang UniversityHangzhou310018China Center for Advanced Measurement Science National Institute of MetrologyBeijing100013China

Surface functionalization of piezoelectric greatly determines its piezo-catalytic activity and selectivity in that functional group affect specific reactants’surface adsorption and activation abilities.Herein,we propose chemical functionalization on the surface of nano-scaled BaTiO_(3) piezoelectric via a one-pot hydrothermal process using polyethylene glycol as surfactant,and evaluate its piezo-catalytic activity and selectivity by degrading model antibiotic and dye reactants under ultrasonic vibrations.Acetate or/and oxalic unidentate ligands on the surface of BaTiO_(3) nanobelts can be formed by controlling precursor and hydrothermal parameters.Particularly,oxalic acid functionalized BaTiO_(3) nanobelts presented a high piezo-catalytic rate constant of 0.068 min^(-1) for Rhodamine B solution and maintained>87%degradation efficiency within 30 min under the condition of ultrasonic bath with 40 kHz and 100 W,which was mainly ascribed to piezo-sensitization effect.This work provides references for the preparation of chemical functionalized catalysts and also contributes to the development of novel catalysts for special applications.

关键词： BaTiO_(3)nanobelts Surface functionalization Piezo-catalysis Piezo-sensitization

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双一流背景下化学实验中心的建设与实践

实验室研究与探索 2024年第1期43卷 130-134页

作者：熊辉高晓莉郭雯霁秦超然付世涛龚跃法华中科技大学化学与化工学院化学实验中心武汉430074

为推动化学实验教学和大型仪器测试平台内涵式并行发展,为教学科研和科普宣传服务,为人才培养服务。根据化学实验中心管理运行情况,探讨了"双一流"背景下院级实验技术平台建设的重要作用,从实验室条件的更新建设、实验教学的改革实践、... 详细信息

为推动化学实验教学和大型仪器测试平台内涵式并行发展,为教学科研和科普宣传服务,为人才培养服务。根据化学实验中心管理运行情况,探讨了"双一流"背景下院级实验技术平台建设的重要作用,从实验室条件的更新建设、实验教学的改革实践、大型仪器资源的开放共享等方面介绍了化学实验中心“双一流”建设的经验。依托平台的建设改善师生实验环境,加强实验安全防护,提升教学科研服务质量,推进科普宣传培训力度,培养基础拔尖创新人才。

关键词：化学实验中心双一流建设实验教学仪器共享

基于大数据的电力通信通道智能路由推荐策略研究

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通信与信息技术 2024年第1期 1-6页

作者：罗云高艳宏张小平罗世涛中通服创立信息科技有限责任公司四川成都610093

面对规模庞大、结构复杂的电力通信网,针对通信调度如何根据业务需求准确、合理、高效地安排通信通道,提出了一种基于分布式图并行计算的大数据智能路由推荐方法。该方法根据电力通信网特点构建电力通信网络拓扑模型、建立优选路由指标... 详细信息

面对规模庞大、结构复杂的电力通信网,针对通信调度如何根据业务需求准确、合理、高效地安排通信通道,提出了一种基于分布式图并行计算的大数据智能路由推荐方法。该方法根据电力通信网特点构建电力通信网络拓扑模型、建立优选路由指标模型,并采用基于分布式图并行计算框架实现并行路由推荐算法。实验证明,该方法具有快速迭代与收敛的特性,在大型复杂的电力通信网络路由推荐与规划中具有良好的应用前景。

关键词：大数据分布式图并行计算电力通信网络路由推荐通信通道

单侧椎弓根切除前中柱重建治疗胸腰椎骨折不愈合的临床观察

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中国中医骨伤科杂志 2024年第4期32卷 77-80,88页

作者：陈广林冯婷婷王进强高鹏高兆青徐世涛潍坊市中医院山东潍坊261041

目的:探讨单侧椎弓根切除减压病椎前中柱重建治疗Ⅲ期Kummell's病的可行性及技术要点,分析该术式的安全性及有效性。方法:回顾性分析2018年9月至2021年1月采用单侧椎弓根切除减压病椎前中柱重建治疗Ⅲ期Kummell's病的患者13例,男1例,女1... 详细信息

目的:探讨单侧椎弓根切除减压病椎前中柱重建治疗Ⅲ期Kummell's病的可行性及技术要点,分析该术式的安全性及有效性。方法:回顾性分析2018年9月至2021年1月采用单侧椎弓根切除减压病椎前中柱重建治疗Ⅲ期Kummell's病的患者13例,男1例,女12例,年龄为(69.53±8.71)岁。术前X线、CT、MR确定椎体内存在真空征(X线/CT)或者椎体内积液积气(MR)。所有患者切除症状侧或者症状较重侧椎板、关节突及椎弓根,对侧使用椎弓根螺钉撑开恢复部分病椎高度,通过椎体内打压植骨、PEEK材料椎间融合器植入进一步恢复病椎高度;同时,采用后路椎弓根螺钉系统固定病椎邻近上下两个节段椎体,术中X线透视确定病椎恢复到有效高度;最终,重建病椎前中柱并纠正后凸畸形。观察指标包括手术时间、术中出血量、术后引流量、病椎椎体高度以及手术前后疼痛视觉模拟量表(VAS)评分、Oswestry功能障碍指数(ODI)评分、病椎局部矢状面Cobb角。结果:所有患者均顺利完成手术,无神经血管损伤,腰背痛、下肢痛麻等症状明显改善。手术时间为(192.00±87.16)min,术中出血量为(249.00±128.26)mL,术后引流量为(283.27±76.71)mL。1例患者出现切口脂肪液化,清创后愈合。1例患者出现下肢肌间静脉血栓。12例患者获得完整随访,1例患者术后半年出现脑梗并肢体活动障碍,失访。随访时间为8~11个月,平均为10.1个月。VAS评分、ODI评分由术前(6.46±1.32)分和(68.16±4.43)分分别改善至(1.18±0.59)分和(15.35±7.64)分,差异有统计学意义(F=16.556,P<0.001;F=29.368,P<0.001)。椎体前缘高度由术前(1.03±0.41)cm改善至术后1周(2.24±0.55)cm和末次随访(2.11±0.46)cm,手术前后变化差异有统计学意义(F=11.578,P<0.001),术后随访变化差异无统计学意义(q=3.12,P=0.081)。局部后凸畸形由术前28.72°±8.12°改善至术后1周8.16°±3.27°和末次随访9.32°±2.13°,手术前后变化差异有统计学意义(F=18.461,P<0.001),术后随访变化差异无统计学意义(q=0.53,P=1.101)。结论:单侧椎弓根切除病椎前中柱重建治疗Ⅲ期Kummell's病不仅可以解除神经压迫,纠正矢状位后凸畸形,重建脊柱稳定性,而且可以减少术中创伤及术后并发症。单侧椎弓根切除减压病椎前中柱重建治疗Ⅲ期Kummell's病有良好的疗效。

关键词：胸腰椎骨折不愈合Ⅲ期单侧椎弓根切除前中柱重建

Conjoint analysis of crowbar switching scheme and its resistancebased on statistical sampling for LVRT of DFIG

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Journal of Modern Power Systems and Clean Energy 2019年第3期7卷 558-567页

作者： Yanbin QU Le gao Guangfu MA Huihui SONG shitao WANG School of Information and Electrical Engineering Harbin Institute of Technology at WeihaiNo.2West Wenhua RoadWeihai 264209China Department of Control Science and Engineering Harbin Institute of TechnologyNo.92West Dazhi StreetNangang DistrictHarbin 150001China State Grid of China Technology College No.500ErhuanSouth RdJinanChina

An active crowbar protective circuit is an effective and common approach for low voltage ride through(LVRT) of a doubly-fed induction generator(DFIG). The crowbar resistance value and its switching scheme both have crucial effects on safety recovery. The effects encountered are correlative dependence and interplay so that analyzing them from a single factor, as most existing LVRT control methods would do, obtains a partial optimal solution. This paper combines these two factors toanalyze their coordination effects on the LVRT control,and to also investigate whether the global optimal performance of these factors can be achieved. The principles for resistance selection and the schemes for crowbar switching are discussed first. Next, the coupling relationship is ana-lyzed based on statistical sampling simulation data with different resistance values and various switching schemes.The results demonstrate that their coordination has critical influence on rotor peak current, DC-link voltage and reactive power. The optimal coordination will be different according to specific requirements. Hence the global optimal combination could be achieved when all requirements are taken into consideration.

关键词： Doubly-fed induction generator(DFIG) Active crowbar Switching scheme Resistance value Statistical sampling data