Typically used thermal insulation materials such as foam insulation and fibreglass may pose notable health risks and environmental impacts thereby resulting in respiratory irritation andwaste disposal issues,respectiv...Typically used thermal insulation materials such as foam insulation and fibreglass may pose notable health risks and environmental impacts thereby resulting in respiratory irritation andwaste disposal issues,respectively.While these materials are affordable and display good thermal insulation,their unsustainable traits pertaining to an intensive manufacturing process and poor disposability are major concerns.Alternative insulation materials with enhanced sustainable characteristics are therefore being explored,and one type of material which has gained notable attention owing to its low carbon footprint and low thermal conductivity is natural fibre.Among the few review studies conducted on Natural Fibre Reinforced Composite(NFRC)insulation boards,the multitude of factors and underlying mechanisms affecting their thermal conductivity performance have been sparsely covered.This review study aimed to address this gap by providing a holistic overview of some of the key intrinsic and extrinsic factors affecting the thermal conductivity performance of NFRCs.Key intrinsic factors pertaining to the microstructural features and to the physico-mechanical traits of NFRCs,namely the fibre lumen size,α,and the fibre-matrix thermal conductivity ratio,β,respectively,were found to largely affect the Transverse Thermal Conductivity(TTC)in NFRC boards.Extrinsic factors,which were found to indirectly affect NFRCs’thermal conductivity,such as fibre pre-processing,composite manufacturing and environmental factors,were also covered.Some of the noteworthy NFRC featureswhich were found to affect their thermal conductivity are volume fraction of fibres,bulk density and porosity.The findings of this study highlight the need for additional research investigation to address the foregoing limitations observed in NFRC thermal insulation boards by considering appropriate natural fibres,composition and fabrication techniques.The fabrication of high-grade NFRC boards,which will display an optimum balance between enhanced thermal insulation and long-term durability performance,could further replace conventionally used thermal insulation boards in the modern building and construction industry.展开更多
为提高雨、雾等恶劣天气下汽车自动紧急制动(automatic emergency braking,AEB)系统的适用性,提出一种基于有限状态机的分级预警与分级制动控制策略。综合考虑驾驶员特性和车辆运行状态,优化碰撞时间(time to collision,TTC)预警阈值与...为提高雨、雾等恶劣天气下汽车自动紧急制动(automatic emergency braking,AEB)系统的适用性,提出一种基于有限状态机的分级预警与分级制动控制策略。综合考虑驾驶员特性和车辆运行状态,优化碰撞时间(time to collision,TTC)预警阈值与制动临界安全距离,通过控制制动减速度变化率,提高制动过程中的驾乘舒适性。在中国新车评价规程(China New Car Assessment Program,C-NCAP)2021版提出的前车静止(car-to-car rear stationary,CCRs)、前车匀速(car-to-car rear moving,CCRm)和车辆碰撞纵向行驶自行车(car-to-bicyclist longitudinal adult,CBLA-50)典型工况下,构建雾天测试场景,通过软件PreScan和MATLAB/Simulink联合仿真AEB分级控制策略,并与固定TTC阈值控制策略进行对比,验证AEB分级控制策略的可行性。仿真结果表明:天气状况为雾天时,固定TTC阈值控制策略在CCRs、CCRm、CBLA-50工况下避撞成功率分别为28.6%、66.7%、60.0%,车速较高时,无法实现避撞;分级控制策略在CCRs、CCRm、CBLA-50工况下的避撞成功率分别为100.0%、100.0%、93.3%,有效避撞的同时保证制动时的驾乘舒适性。展开更多
现有的前向碰撞预警系统大多采用多个毫米波雷达叠加或毫米波雷达与视觉传感器融合等方式,存在成本高、算法受限等问题。在比较多种传感器的性能及应用优、缺点后,选择双目视觉传感器作为前向碰撞预警系统传感器。将改进后的碰撞时间(Ti...现有的前向碰撞预警系统大多采用多个毫米波雷达叠加或毫米波雷达与视觉传感器融合等方式,存在成本高、算法受限等问题。在比较多种传感器的性能及应用优、缺点后,选择双目视觉传感器作为前向碰撞预警系统传感器。将改进后的碰撞时间(Time to Collision,TTC)算法与卡尔曼滤波融合,结合双目视觉传感器,比较TTC值与适应性阈值,评估风险等级,确保行车安全,降低事故率。在Matlab环境下,基于改进算法对两个不同行车场景进行仿真分析。结果表明,与传统的TTC算法相比,融合卡尔曼滤波TTC算法的碰撞时间预警响应及时性和可靠性显著提高。展开更多
目的探讨罕见嵌合体合并单基因变异的产前诊断策略、分子形成机制及临床预后,为遗传咨询与管理提供循证依据。方法2025年9月就诊于湛江市妇幼保健院的1例不良孕产史孕妇,联合超声检查、家系短串联重复序列(short tandem repeats,STR)比...目的探讨罕见嵌合体合并单基因变异的产前诊断策略、分子形成机制及临床预后,为遗传咨询与管理提供循证依据。方法2025年9月就诊于湛江市妇幼保健院的1例不良孕产史孕妇,联合超声检查、家系短串联重复序列(short tandem repeats,STR)比对、母源污染鉴定、染色体核型分析、染色体微阵列分析(chromosomal microarray analysis,CMA)、Sanger测序并结合文献复习分析相关特征。结果羊水核型分析结果为46,XY,母体DNA污染检测阴性;STR分型显示胎儿13号及21号染色体呈三峰模式(峰高约为2∶1∶1),家系比对证实该结果来源于1种母源等位基因及2种父源等位基因;CMA明确胎儿存在两种46,XY细胞系,各占50%即为46,XY/46,XY异源嵌合体;Sanger测序结果证实胎儿携带了四肽重复序列结构域7A基因(tetratricopeptide repeat domain 7A,TTC7A)复合杂合变异;超声检查提示胎儿存在多发发育异常。结论STR与CMA联合应用可有效诊断46,XY/46,XY异源嵌合体;本例嵌合体可能是母亲生殖细胞孤雌分裂产生双卵子,分别与同一父亲Y染色体基因型不同的精子结合形成双受精卵后胚胎融合而成,临床需结合不良孕产史及单基因变异特征开展遗传咨询。展开更多
文摘Typically used thermal insulation materials such as foam insulation and fibreglass may pose notable health risks and environmental impacts thereby resulting in respiratory irritation andwaste disposal issues,respectively.While these materials are affordable and display good thermal insulation,their unsustainable traits pertaining to an intensive manufacturing process and poor disposability are major concerns.Alternative insulation materials with enhanced sustainable characteristics are therefore being explored,and one type of material which has gained notable attention owing to its low carbon footprint and low thermal conductivity is natural fibre.Among the few review studies conducted on Natural Fibre Reinforced Composite(NFRC)insulation boards,the multitude of factors and underlying mechanisms affecting their thermal conductivity performance have been sparsely covered.This review study aimed to address this gap by providing a holistic overview of some of the key intrinsic and extrinsic factors affecting the thermal conductivity performance of NFRCs.Key intrinsic factors pertaining to the microstructural features and to the physico-mechanical traits of NFRCs,namely the fibre lumen size,α,and the fibre-matrix thermal conductivity ratio,β,respectively,were found to largely affect the Transverse Thermal Conductivity(TTC)in NFRC boards.Extrinsic factors,which were found to indirectly affect NFRCs’thermal conductivity,such as fibre pre-processing,composite manufacturing and environmental factors,were also covered.Some of the noteworthy NFRC featureswhich were found to affect their thermal conductivity are volume fraction of fibres,bulk density and porosity.The findings of this study highlight the need for additional research investigation to address the foregoing limitations observed in NFRC thermal insulation boards by considering appropriate natural fibres,composition and fabrication techniques.The fabrication of high-grade NFRC boards,which will display an optimum balance between enhanced thermal insulation and long-term durability performance,could further replace conventionally used thermal insulation boards in the modern building and construction industry.
文摘为提高雨、雾等恶劣天气下汽车自动紧急制动(automatic emergency braking,AEB)系统的适用性,提出一种基于有限状态机的分级预警与分级制动控制策略。综合考虑驾驶员特性和车辆运行状态,优化碰撞时间(time to collision,TTC)预警阈值与制动临界安全距离,通过控制制动减速度变化率,提高制动过程中的驾乘舒适性。在中国新车评价规程(China New Car Assessment Program,C-NCAP)2021版提出的前车静止(car-to-car rear stationary,CCRs)、前车匀速(car-to-car rear moving,CCRm)和车辆碰撞纵向行驶自行车(car-to-bicyclist longitudinal adult,CBLA-50)典型工况下,构建雾天测试场景,通过软件PreScan和MATLAB/Simulink联合仿真AEB分级控制策略,并与固定TTC阈值控制策略进行对比,验证AEB分级控制策略的可行性。仿真结果表明:天气状况为雾天时,固定TTC阈值控制策略在CCRs、CCRm、CBLA-50工况下避撞成功率分别为28.6%、66.7%、60.0%,车速较高时,无法实现避撞;分级控制策略在CCRs、CCRm、CBLA-50工况下的避撞成功率分别为100.0%、100.0%、93.3%,有效避撞的同时保证制动时的驾乘舒适性。
文摘现有的前向碰撞预警系统大多采用多个毫米波雷达叠加或毫米波雷达与视觉传感器融合等方式,存在成本高、算法受限等问题。在比较多种传感器的性能及应用优、缺点后,选择双目视觉传感器作为前向碰撞预警系统传感器。将改进后的碰撞时间(Time to Collision,TTC)算法与卡尔曼滤波融合,结合双目视觉传感器,比较TTC值与适应性阈值,评估风险等级,确保行车安全,降低事故率。在Matlab环境下,基于改进算法对两个不同行车场景进行仿真分析。结果表明,与传统的TTC算法相比,融合卡尔曼滤波TTC算法的碰撞时间预警响应及时性和可靠性显著提高。
