Investigating the influence of radiation on glass fibre composites is essential for their use in space and aerospace environment.Gaining insight into the damage mechanisms caused by gamma irradiation,can improve the s...Investigating the influence of radiation on glass fibre composites is essential for their use in space and aerospace environment.Gaining insight into the damage mechanisms caused by gamma irradiation,can improve the safety and resilience of structures.This paper is aimed at investigating the failure mode and damage of gamma-irradiated repurposed pultruded glass fibre-reinforced polyester subjected to lowvelocity impact using three types of non-destructive techniques.Three sets of differently layered configurations(CRC,WCRW,W2CR2C)consisting of chopped(c),roving(r),and weaved(w)fibre-reinforced polyester are applied in this study.Drop hammer test is applied to evaluate the low-impact resistance properties of Gamma-irradiated composite at 100 kGy,500 kGy,and 1000 kGy.Preliminary flexural and hardness tests are conducted to further assess the behaviour of irradiated polymer composites.Further,the damage modes associated with the low-impact test are characterised using infrared thermography,flat panel digital radiography,and microscope observation.The results show that the composites irradiated with various doses display good impact resistance at 20 J,presenting minor damages in the form of dents on the surface.The irradiated CRC and WCRW display best impact resistance at 500 kGy,while W2CR2C at 1000 kGy.This shows that the layering sequence of reinforcement fibre can influence the impact resistance of irradiated composites.Apart from that,the application of non-destructive techniques show different damage mechanisms in the form resin cracks,yarn splitting/fracture,and matrix splitting when the composites are exposed at high and low irradiation doses.These findings offer valuable data for the defence industry,particularly in the areas of repair,maintenance,and the development of new materials.展开更多
为了研究不同码型的卷积码在水下湍流信道中的误码率(BER)性能,采用接受-拒绝采样模拟湍流信道乘性干扰,并选择二进制相移键控(BPSK)调制方式,建立Gamma-Gamma湍流信道通信系统仿真模型。仿真结果表明:在不同强度的湍流信道中,采用卷积...为了研究不同码型的卷积码在水下湍流信道中的误码率(BER)性能,采用接受-拒绝采样模拟湍流信道乘性干扰,并选择二进制相移键控(BPSK)调制方式,建立Gamma-Gamma湍流信道通信系统仿真模型。仿真结果表明:在不同强度的湍流信道中,采用卷积码编码均能提升系统的BER性能;卷积码的码率越小,系统BER性能提升越显著;随着信噪比(SNR)增大,记忆深度越长,系统BER下降速度越快;采用软译码比采用硬译码时增益至少提升2.82 d B;卷积码的解码不仅受当前信息的影响,还与之前的码元信息有关。展开更多
针对夜间场景下低照度图像整体亮度不足、边缘难以辨识与色彩失真等问题,在HSV色彩空间的基础上,提出一种基于多尺度自引导锐化-平滑图像滤波(Sharpening-Smoothing Image Fil⁃ter,SSIF)的低照度图像增强方法.首先,利用HSV空间色彩亮度...针对夜间场景下低照度图像整体亮度不足、边缘难以辨识与色彩失真等问题,在HSV色彩空间的基础上,提出一种基于多尺度自引导锐化-平滑图像滤波(Sharpening-Smoothing Image Fil⁃ter,SSIF)的低照度图像增强方法.首先,利用HSV空间色彩亮度分离的特性,对V分量使用多尺度自引导锐化-平滑图像滤波,准确估计光照分量进而求得精确的反射分量.其次,针对光照分量分布不均的问题,提出一种二维自适应伽马变换算法并通过大量对比选取最佳参数,对较暗区域亮度进行拉伸,同时抑制较亮区域的亮度,使整体图像光照更加均匀,图像亮度更符合人眼视觉.再次,针对反射分量存在部分边缘模糊与噪声的问题,提出多尺度钝化掩蔽算法,在抑制噪声的同时能够有效增强图像细节信息,提升整体图像动态范围.最后,对S分量使用自适应饱和度增强算法,将增强后的S分量、V分量与保持不变的H分量合并转到RGB图像,并与带色彩恢复的多尺度视网膜增强算法(Multi-Scale Retinex with Color Restoration,MSRCR)中的色彩恢复因子结合得到最终增强图像.实验结果表明:所提低照度图像增强算法的基于精细自然场景统计的图像质量盲评价指标和平均梯度较其他对比算法分别提高了14.62%、32.10%,不仅能够有效地解决图像亮度分布不均问题,而且能够提高图像轮廓细节的丰富程度和对比度,整体效果优于其他对比算法.展开更多
目的:比较采用动力髋螺钉(dynamic hip screw,DHS)、Gamma钉和防旋型股骨近端髓内钉(proximal femoral nail anti-rotation,PFNA)治疗老年骨质疏松性股骨粗隆间骨折的效果,探讨老年骨质疏松性股骨粗隆间骨折合理的内固定治疗方法。方法:...目的:比较采用动力髋螺钉(dynamic hip screw,DHS)、Gamma钉和防旋型股骨近端髓内钉(proximal femoral nail anti-rotation,PFNA)治疗老年骨质疏松性股骨粗隆间骨折的效果,探讨老年骨质疏松性股骨粗隆间骨折合理的内固定治疗方法。方法:2000年2月至2006年10月,分别采用DHS(DHS组,n=59)、Gamma钉(Gamma钉组,n=46)和PFNA(PFNA组,n=53)治疗并随访老年骨质疏松性股骨粗隆间骨折患者158例。比较3组患者手术情况、术中和术后并发症、疗效及骨折愈合时间。结果:各组间平均手术时间和术中出血量两两比较均有统计学差异(P<0.01)。三组术中、术后并发症发生率有统计学差异(P<0.05),PFNA组术中、术后并发症发生率比DHS组和Gamma钉组低。DHS组、Gamma钉组和PFNA组优良率分别为86.44%、84.78%和90.57%,组间疗效差异无统计学意义(P>0.05)。PFNA组与DHS组骨折愈合时间有统计学差异(P<0.01),而Gamma钉组与PFNA组间无统计学差异(P>0.05)。结论:应用DHS、Gamma钉和PFNA治疗老年股骨粗隆间骨折,在疗效方面无明显差异。PFNA内固定平均手术时间最短,术中出血量最少,术中、术后并发症发生率低,骨折愈合时间短。PFNA对骨折端的血循环影响和骨质破坏较小,固定更为牢靠,是治疗老年骨质疏松性股骨粗隆间骨折的合理手术方法。展开更多
为了提高剩余寿命预测的可信度,针对进行过加速老化试验的产品,提出利用Gamma过程参数的非共轭先验分布进行Bayesian统计推断的剩余寿命预测方法.将加速老化数据作为先验信息,利用Gamma过程进行老化建模,通过加速因子获得形状参数在工...为了提高剩余寿命预测的可信度,针对进行过加速老化试验的产品,提出利用Gamma过程参数的非共轭先验分布进行Bayesian统计推断的剩余寿命预测方法.将加速老化数据作为先验信息,利用Gamma过程进行老化建模,通过加速因子获得形状参数在工作应力下的折算值,使用Anderson-Darling统计量确定随机参数的先验分布.将产品工作中的少量实测数据作为现场信息,利用基于Gibbs抽样的Markov Chain Monte Carlo(MCMC)仿真得到参数的后验均值.以某型导弹电连接器为例说明了该方法的研究意义和工程应用价值.展开更多
基金funded by Universiti Tenaga Nasional(UNITEN),Malaysia for supporting this research under the Dato'Low Tuck Kwong International Grant,project code 20238002DLTKsupport for this work from the Ministry of Higher EducationMalaysia through the Higher Institution Center of Excellence(HICoE 2023-JPT(BPKI)1000/016/018/34(5))program+2 种基金supported by Tenaga Nasional Berhad(TNB)and UNITEN through the BOLD Refresh Postdoctoral Fellowships under Grant J510050002-IC-6 BOLDREFRESH2023-Centre of ExcellencePrince Sultan University for their supportIndustrial Technology Division,Malaysian Nuclear Agency for their support in this research work.
文摘Investigating the influence of radiation on glass fibre composites is essential for their use in space and aerospace environment.Gaining insight into the damage mechanisms caused by gamma irradiation,can improve the safety and resilience of structures.This paper is aimed at investigating the failure mode and damage of gamma-irradiated repurposed pultruded glass fibre-reinforced polyester subjected to lowvelocity impact using three types of non-destructive techniques.Three sets of differently layered configurations(CRC,WCRW,W2CR2C)consisting of chopped(c),roving(r),and weaved(w)fibre-reinforced polyester are applied in this study.Drop hammer test is applied to evaluate the low-impact resistance properties of Gamma-irradiated composite at 100 kGy,500 kGy,and 1000 kGy.Preliminary flexural and hardness tests are conducted to further assess the behaviour of irradiated polymer composites.Further,the damage modes associated with the low-impact test are characterised using infrared thermography,flat panel digital radiography,and microscope observation.The results show that the composites irradiated with various doses display good impact resistance at 20 J,presenting minor damages in the form of dents on the surface.The irradiated CRC and WCRW display best impact resistance at 500 kGy,while W2CR2C at 1000 kGy.This shows that the layering sequence of reinforcement fibre can influence the impact resistance of irradiated composites.Apart from that,the application of non-destructive techniques show different damage mechanisms in the form resin cracks,yarn splitting/fracture,and matrix splitting when the composites are exposed at high and low irradiation doses.These findings offer valuable data for the defence industry,particularly in the areas of repair,maintenance,and the development of new materials.
文摘为了研究不同码型的卷积码在水下湍流信道中的误码率(BER)性能,采用接受-拒绝采样模拟湍流信道乘性干扰,并选择二进制相移键控(BPSK)调制方式,建立Gamma-Gamma湍流信道通信系统仿真模型。仿真结果表明:在不同强度的湍流信道中,采用卷积码编码均能提升系统的BER性能;卷积码的码率越小,系统BER性能提升越显著;随着信噪比(SNR)增大,记忆深度越长,系统BER下降速度越快;采用软译码比采用硬译码时增益至少提升2.82 d B;卷积码的解码不仅受当前信息的影响,还与之前的码元信息有关。
文摘针对夜间场景下低照度图像整体亮度不足、边缘难以辨识与色彩失真等问题,在HSV色彩空间的基础上,提出一种基于多尺度自引导锐化-平滑图像滤波(Sharpening-Smoothing Image Fil⁃ter,SSIF)的低照度图像增强方法.首先,利用HSV空间色彩亮度分离的特性,对V分量使用多尺度自引导锐化-平滑图像滤波,准确估计光照分量进而求得精确的反射分量.其次,针对光照分量分布不均的问题,提出一种二维自适应伽马变换算法并通过大量对比选取最佳参数,对较暗区域亮度进行拉伸,同时抑制较亮区域的亮度,使整体图像光照更加均匀,图像亮度更符合人眼视觉.再次,针对反射分量存在部分边缘模糊与噪声的问题,提出多尺度钝化掩蔽算法,在抑制噪声的同时能够有效增强图像细节信息,提升整体图像动态范围.最后,对S分量使用自适应饱和度增强算法,将增强后的S分量、V分量与保持不变的H分量合并转到RGB图像,并与带色彩恢复的多尺度视网膜增强算法(Multi-Scale Retinex with Color Restoration,MSRCR)中的色彩恢复因子结合得到最终增强图像.实验结果表明:所提低照度图像增强算法的基于精细自然场景统计的图像质量盲评价指标和平均梯度较其他对比算法分别提高了14.62%、32.10%,不仅能够有效地解决图像亮度分布不均问题,而且能够提高图像轮廓细节的丰富程度和对比度,整体效果优于其他对比算法.
文摘目的:比较采用动力髋螺钉(dynamic hip screw,DHS)、Gamma钉和防旋型股骨近端髓内钉(proximal femoral nail anti-rotation,PFNA)治疗老年骨质疏松性股骨粗隆间骨折的效果,探讨老年骨质疏松性股骨粗隆间骨折合理的内固定治疗方法。方法:2000年2月至2006年10月,分别采用DHS(DHS组,n=59)、Gamma钉(Gamma钉组,n=46)和PFNA(PFNA组,n=53)治疗并随访老年骨质疏松性股骨粗隆间骨折患者158例。比较3组患者手术情况、术中和术后并发症、疗效及骨折愈合时间。结果:各组间平均手术时间和术中出血量两两比较均有统计学差异(P<0.01)。三组术中、术后并发症发生率有统计学差异(P<0.05),PFNA组术中、术后并发症发生率比DHS组和Gamma钉组低。DHS组、Gamma钉组和PFNA组优良率分别为86.44%、84.78%和90.57%,组间疗效差异无统计学意义(P>0.05)。PFNA组与DHS组骨折愈合时间有统计学差异(P<0.01),而Gamma钉组与PFNA组间无统计学差异(P>0.05)。结论:应用DHS、Gamma钉和PFNA治疗老年股骨粗隆间骨折,在疗效方面无明显差异。PFNA内固定平均手术时间最短,术中出血量最少,术中、术后并发症发生率低,骨折愈合时间短。PFNA对骨折端的血循环影响和骨质破坏较小,固定更为牢靠,是治疗老年骨质疏松性股骨粗隆间骨折的合理手术方法。
文摘为了提高剩余寿命预测的可信度,针对进行过加速老化试验的产品,提出利用Gamma过程参数的非共轭先验分布进行Bayesian统计推断的剩余寿命预测方法.将加速老化数据作为先验信息,利用Gamma过程进行老化建模,通过加速因子获得形状参数在工作应力下的折算值,使用Anderson-Darling统计量确定随机参数的先验分布.将产品工作中的少量实测数据作为现场信息,利用基于Gibbs抽样的Markov Chain Monte Carlo(MCMC)仿真得到参数的后验均值.以某型导弹电连接器为例说明了该方法的研究意义和工程应用价值.
