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The paired comparison (PC) is an easy and effective way to distinguish the nuances among sound stimuli of diesel engine in sound quality subjective evaluation. However, the PC method is inefficient for the subjective evaluation of large quantities of stimulus or to rank the results of overall perception of sound stimuli. To overcome the shortcoming of the PC method, this paper presents a comprehensive evaluation method of diesel engine sound quality based on the PC method, uniform design sampling (UDS), and the improved analytic hierarchy process (AHP). An hierarchical tree of comprehensive evaluation models of diesel engine sound quality is constructed and simplified through UDS to ensure that the sound sample size is in the application range of the PC method or the grouped paired-wise comparison (GPC) method. An improved AHP is developed by introducing a new method calculating the relative weight based on evaluators’ preference order instead of the traditional 1–9 scale method, which reduces subjective liberty and difficulty of the consistency of the judgment matrix meeting the requirement, and the requirements of evaluators’ specialized knowledge. With three diesel engines’ noise stimuli as example, a realization of sound quality comprehensive evaluation based on UDS-AHP method with the GPC method is introduced. The results show that the proposed subjective comprehensive evaluation method can accurately provide the ranks of the sound stimuli over all subjective perception with a significant decrease of the evaluation workload. 相似文献
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A novel sound quality simulation approach was proposed to optimize the acoustic performance of a four-cylinder diesel engine. Finite element analysis, single-input and multiple-output technology, flexible multi-body dynamics, and boundary element codes were used to acquire the hexahedron-element model, experimental modal frequencies, vibration velocities, and structurally radiated noise of the block, respectively. The simulated modal frequencies and vibration velocities agreed well with the experimental data, which validated the finite-element block. The acoustic response showed that considerable acoustic power levels existed in 1500–1900 Hz and 2300–2800 Hz as the main frequency ranges to optimize the block acoustics. Then, the optimal block is determined in accordance with the novel approach, which reduces the overall value, high-frequency amplitudes, and peak values of acoustic power; thus, the loudness, sharpness, and roughness decline to make the sound quieter, lower-pitched, and smoother, respectively. Finally, the optimal block was cast and bench-tested. The results reveal that the sound quality of the optimal-block engine is substantially improved as numerically expected, which verifies the effectiveness of the research approach. 相似文献
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Jie ZHANG ;Guang-xu HAN ;Xin-biao XIAO ;Rui-qian WANG ;Yue ZHAO ;Xue-song JIN 《浙江大学学报(A卷英文版)》2014,(12):1002-1018
研究目的：研究高速列车车轮多边形特征对轮轨噪声和车内噪声的影响规律,讨论目前国内高速列车车轮镟修指标的不足,为高速列车车轮镟修方法的优化改进提供科学依据。创新要点：系统分析高速列车车轮多边形阶次、幅值和相位等参数对车内噪声的影响规律;提出车轮镟修中仅考虑车轮径跳作为限值是不够的。研究方法：1．基于线路试验,初步分析高速列车车轮多边形状态对车内噪声的影响,进而对车轮多边形特征进行剖析;2．基于带通滤波和快速傅里叶变换,使用MATLAB程序生成不同阶次、幅值和相位的车轮多边形粗糙度数据;3．基于TWINS轮轨噪声原理,使用HWTNS预测含有不同车轮多边形特性的轮轨噪声;4．基于混合有限元-统计能量分析（FE—SEA）方法,建立高速列车客室端部车内噪声预测模型,预测车内噪声;5．通过分析车轮多边形参数、车轮径跳和车内噪声之间的相互关系,研究目前的高速列车车轮镟修指标是否合适。重要结论：1．高速列车车轮径跳值相同,但车轮多边形状态不同时,轮轨噪声与车内噪声有明显差异;2．当车轮多边形幅值相同时,高阶多边形可以引起更高的轮轨噪声和车内噪声;3．改变车轮多边形的相位,可以获得不同的车轮径跳值,但是对轮轨噪声和车内噪声几乎没有影响。 相似文献
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建立图像融合质量评价标准对于在不同的应用场景中选择适当的融合算法,以及对现有融合算法的改进和研究新的融合算法都是至关重要的。本文在分析目前广泛使用的图像融合质量主客观评价方法的基础上,对图像融合质量进行了主客观评价并对主客观评价结果进行了相关性分析,发现结合了人类视觉特性的客观评价方法与主观分析结果较为一致,充分说明了建立新型的、结合主观因素与客观因素的图像融合评价准则的必要性。 相似文献
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黄昕龙花海燕陈世辉 《福建工程学院学报》2020,(6):524-529
产品的表面质量差严重制约了熔融沉积成型(fused deposition modeling,FDM)工艺的发展,通过粗糙度成型机理构建参数模型是提升FDM 成型件表面质量的重要途径。文章以某FDM 打印设备成型件的水平表面粗糙度为例,通过探讨参数三次曲线与多段直线拟合的丝宽模型,利用粗糙度的几何机理提出了基于3 个主要工艺参数的回归模型,采用样条变换的非线性偏最小二乘回归(partial least squares,PLSR)建立对所选参数的有效预测模型,并对建模中未覆盖的不同打印参数下的实验数据样本进行校验,分析工艺参数对水平表面粗糙度的影响。通过以上研究方法,提高了水平表面粗糙度预测效率,获取了相关的经验知识。 相似文献
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虹膜识别中,图像质量除受到采集设备、环境光照、目标位置、目标状态等因素影响外,错误的图像分割也会导致图像质量下降,因此单一量度或较少量度都不能准确评价用于匹配计算的虹膜图像质量.基于此设计了可用虹膜区、虹膜大小、清晰度、扩张度等八个评价因子;研究了各评价因子所表征的图像质量特性;提出了利用图像分割参数计算各评价因子的方法;根据实验得到的各评价因子阈值以及图像分割可能的错误,对质量评价因子进行校准;最后融合校准后的因子形成虹膜图像质量评价值.实验结果显示所提出的方法可有效评价虹膜图像质量. 相似文献
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INTRODUCTION Wavefront coding was introduced to increase the depth of focus for optical system in 1995 by Dowski and Cathey (1995). A cubic phase mask was placed in pupil plane to encode the wavefront of the optical system by which the intermediate image formed could almost be invariant in a large depth of focus, and the intermediate image could be digitally restored into clear one. This technique shows wonderful re- sults in extending the depth of focus (Cathey and Dowski, 2002; Gómez-… 相似文献
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邱盛明 《邵阳学院学报(社会科学版)》1998,(5)
本文提出了对音响系统进行音质评价的必要性和可行性,并从人耳听觉的基本特性出发,对各类音质评价术语进行了综合分析和初步量化。在阐述技术要素与音质评价关系的基础上,初步揭示了对音响系统主客观评价的内在联系。最后提出了提高音质评价可信度的途径和方法。 相似文献
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目的：考察地震灾区高中生外向性、社会期望和主观幸福感之间的关系。方法：采用大五人格简版量表的外向性分量表、儿童社会期望量表和主观幸福感指数量表对地震灾区的133名中学生进行调查。结果：相关分析结果显示,震后灾区高中生的外向性、社会期望和主观幸福感之间存在显著正相关,外向性和社会期望之间存在微弱正相关;层次回归分析显示,社会期望可以调节外向性和主观幸福感之间的关系。结论：震后灾区高中生的外向性、社会期望对其主观幸福感都存在一定的正向预测作用,且社会期望在外向性和主观幸福感之间还存在调节作用。 相似文献
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崔雪峰 《沈阳教育学院学报》2010,12(3):55-57,67
按照声音的属性——声音的自然属性和声音的社会属性,将声音划分为自然性声音和社会性声音,并进一步分析了社会性声音的六个主要特征,指出这些特征在声音的感知过程中可以相互联系,相互作用,并且对语言感知的理解及教学实践有一定的启示。 相似文献
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A psychometrically sound instrument is essential for the study of children's subjective impressions about social support. To evaluate such an instrument, 249 children, 6-12 years old, from a population-based sample of black and white families (50% single mothers, 50% two parents) were studied. The newly developed instrument, "My Family and Friends," consists of 12 dialogues, based on Vygotskian principles, and yields information about (a) children's perceptions of the availability of individuals in their networks to provide different types of social support and (b) their satisfaction with the help they receive. Children collaborate in interactive dialogues and manipulate personalized props. Collectively, the data indicate that subjective impressions about social support can be measured in a reliable and valid manner from early childhood through adolescence, and that children understand and care about the quality and the differentiation of support (i.e., emotional, informational, instrumental, and companionship) within their social support networks. Further, children report significant variations in social support when undergoing major family upheaval. 相似文献
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ZHANG Wen-zi CHEN Yan-ping ZHAO Ting-yu YE Zi YU Fei-hong 《浙江大学学报(A卷英文版)》2007,8(2):180-185
By applying the wavefront coding technique to an optical system, the depth of focus can be greatly increased. Several complicated methods, such as Fisher Information based method, have already been taken to optimize for the best pupil phase mask in ideal condition. Here one simple point spread function （PSF） based method with only the standard deviation method used to evaluate the PSF stability over the depth of focus is taken to optimize for the best coefficients of pupil phase mask in practical optical systems. Results of imaging simulations for optical systems with and without pupil phase mask are presented, and the sharpness of image is calculated for comparison. The optimized results showed better and much more stable imaging quality over the original system without changing the position of the image plane. 相似文献
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《British journal of educational technology : journal of the Council for Educational Technology》2018,49(3):412-426
e‐Learning courses are fast becoming common‐place, yet the success of these online courses varies considerably. Since limited research addresses the issue of e‐learning quality (ELQ) of service in higher education environments, there is an increasing need to effectively assess ELQ. In this paper, we argue that to obtain a satisfactory e‐learning student experience, we must offer more than access to learning material. The research proposes an extended SERVQUAL model, the ELQ model, which in addition to key service constructs, facilitates consideration of both information and system quality factors. Exploratory Factor Analysis is conducted to investigate the reliability and validity of the measurement model, and multiple regression analysis is used to test the research model. Data analysis reveals that Assurance, Responsiveness, Tangibility, Course Website and Learning Content have a positive correlation with the perception of ELQ. e‐Learning students value a stable, and easy to use e‐learning environment, yet do not perceive empathy and reliability as significant to student perception of ELQ. 相似文献
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针对目标和背景在同一平面的图像，提出一种双阈值分割方法获取图像由目标过渡到背景的边缘区域，并将提取的边缘区域平均梯度用于图像清晰度的评价，评价效果较好． 相似文献
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立体视觉是人们在观察事物过程中的一种立体知觉,又称深度知觉。在对立体视觉的敏锐度要求较高的职业中,立体视觉的好与坏会直接影响工作质量,甚至对于某些行业来说,会直接威胁到从业者的人身安全。因此,选取一种有效简捷的方法来判断从业人员的立体视觉,对立体视觉的应用有着重要的实践意义。研究目的:以测量立体视觉的传统方法三杆法为校标,检验随机点立体图的实证效度。方法:测量43名大学生的立体视觉,使用斯皮尔曼等级相关与皮尔逊相关检验随机点立体图法的校标关联效度。结果:三杆法与随机点立体图法的测量结果存在显著相关。结论:随机点立体图能有效地测量立体视觉。 相似文献
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吴双双 《潍坊教育学院学报》2013,26(1):42-45
为了考察大学生领悟社会支持与生活满意度之间的关系,本文采用《领悟社会支持量表》(PSSS)和《生活满意度量表》(SLS)对368名被试大学生进行问卷调查。结果如下:(1)领悟社会支持和生活满意度在人口学变量上的分析表明,性别在领悟社会支持及其各要素上存在主效应;性别和专业在家庭支持上存在交互效应;专业在生活满意度上存在主效应。(2)领悟社会支持和生活满意度的相关分析表明,大学生的生活满意度与领悟社会支持总分、家庭支持、朋友支持及其他支持均呈显著正相关。(3)生活满意度对领悟社会支持及各因素的回归分析表明,家庭支持、朋友支持和其他支持均能显著预测大学生的生活满意度。通过分析,得出如下结论:大学生领悟社会支持是大学生生活满意度的重要影响因素。 相似文献
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网络交互质量是影响网络教学效果的重要因素。已有的网络交互教学成效评价系统缺乏对学习过程的监控和对学习者的良好建模,评价大多凭借专家经验,评估的主观随意性大,评价结果与实际值存在一定的误差。贝叶斯网络有很强大的解决不确定问题的处理水平,是目前基于概率的不确定表达和智能推理方面最有效的理论模型之一。基于贝叶斯网络的网络交互教学成效评价系统,基于领域知识关系构建贝叶斯网络学生模型,并引入模糊数学变换方法对学生认知水平进行评估。能减少不正常因素的干扰,提高对学生认知能力评价的精确度．实现对网络教学交互的质量评估和个性化导学。 相似文献