基于消费者低碳偏好的供应链碳减排策略     

熊榕  梁承姬  韩婷婷 《上海海事大学学报》2019,40(4):52-60

针对一个占主导地位的零售商和两个制造商(名牌产品和普通产品制造商)组成的二级供应链,考虑制造商之间的定价顺序和低碳偏好消费者对普通产品的接受度,分别构建普通产品制造商采用或不采用减排技术情景下的收益模型,得出各情景下最优零售价格和收益。研究发现:零售商选择销售哪种产品与顾客对普通产品的接受度有关;普通产品制造商的减排策略主要取决于减排成本。在相同减排策略下,若顾客对普通产品接受度较大,制造商同时定价时产品的最优零售价小于等于不同时定价时产品的最优零售价,而同时定价时制造商的最优收益大于等于不同时定价时的最优收益,因此两个制造商应同时定价以获得更大的收益。  相似文献   

A meta-analytic review of interventions to improve children’s attitudes toward their peers with intellectual disabilities     

《Contemporary educational psychology》2021

Children’s biases toward their peers with intellectual disabilities tend to have negative developmental and social consequences for those with intellectual disabilities. As a result, researchers developed intervention programs to reduce biases toward children with intellectual disabilities. This meta-analysis is a quantitative summary of 59 studies and 144 hypothesis tests involving intervention programs to change children’s attitudes toward their peers with intellectual disabilities. Results revealed an overall significant effect (d = 0.44): following intervention programs, children’s attitudes toward their peers with intellectual disabilities increased. Moderators indicate that the most effective interventions were those that occurred over multiple sessions, involved active engagement in multiple strategies and social interactions, emphasized equal status contact that was unstructured or indirect, and had little adult guidance. Interventions had no effect on changing children’s perceptions of competence and participants in junior high had more negative attitudes following the interventions. Findings provide guidance for researchers, educators, and counselors who seek methodologies to reduce biases toward children with intellectual disabilities.  相似文献   

基于极化特征和纹理特征的PolSAR影像建筑物提取方法     

马肖肖  程博  刘岳明  崔师爱  梁琛彬 《中国科学院大学学报》2019,36(5):682-693

极化合成孔径雷达（PolSAR）以其多参数、多通道、多极化、信息记录更加完整等特点，在城市地物提取领域中发挥着重要作用，并已成为遥感影像研究领域的热点。选择覆盖苏州市的Radarsat2影像，利用极化非相干分解法和灰度共生矩阵法分别提取19种极化特征和8种纹理特征，通过分析建筑物、植被和水体的极化特征和纹理特征进行特征组合，结合主成分分析法（PCA）和支持向量机法（SVM）对城市建筑物进行提取，并定量评估精度。结果表明：基于极化特征的建筑物提取精度最高为92.4%；基于纹理特征的提取精度最高为88.9%；极化特征与纹理特征相结合可以提高精度，最高精度为93.7%；PCA特征融合算法具有较高的运算效率，同时提高了精度。  相似文献   

低负荷加压训练改善自发性高血压大鼠的血压效果及机制研究     

谭朝文  赵彦  俞莹莹  马晓缓  郑玉婵 《体育科学》2020,(3):46-53,63

目的:探究低负荷加压训练对自发性高血压大鼠的降压效果及其作用机制。方法:选取4周龄雄性自发性高血压大鼠,随机分为对照组(高血压安静组)、低负荷训练组、低负荷加压训练组和高负荷训练组。低负荷训练组进行35%~55%1RM递进式低负荷爬梯训练,低负荷加压训练组进行30%~40%血流受限结合35%~55%1RM递进式低负荷爬梯训练,高负荷训练组进行55%~75%1RM递进式高负荷爬梯训练,训练后测定血压、血液中内皮素-1、血管内皮生长因子、一氧化氮合成酶的表达和心肌组织中内皮型一氧化氮合成酶的表达。结果:1)与对照组、高负荷训练组相比,低负荷加压训练组收缩压、舒张压显著下降(P<0.05);与低负荷训练组相比,低负荷加压训练组舒张压显著下降(P<0.05)。2)与对照组相比,低负荷加压训练组血液中内皮素-1表达显著下调(P<0.05),血管内皮生长因子和一氧化氮合成酶表达显著上调(P<0.05);3)与对照组相比,低负荷加压训练组心肌中内皮型一氧化氮合成酶表达显著上调(P<0.05);4)在低负荷加压训练组中,收缩压与内皮素-1呈正相关,相关性分析具有统计学意义(P<0.05);收缩压与一氧化氮合成酶、血管内皮生长因子、内皮型一氧化氮合成酶均呈负相关,相关性分析具有统计学意义(P<0.05)。结论:1)低负荷加压训练降压效果优于高负荷训练;2)低负荷加压训练能够通过下调血液中内皮素-1的表达,上调血液中血管内皮生长因子和一氧化氮合成酶的表达,同时上调心肌中内皮型一氧化氮合成酶表达,改善内皮细胞功能,达到降压的效果。  相似文献   

Ancient Mural Classification Method Based on Improved AlexNet Network     

Jianfang Cao  Hongyan Cui  Qi Zhang  Zibang Zhang 《文物保护研究》2020,65(7):411-423

ABSTRACT

As an important part of art and culture, ancient murals depict a variety of different artistic images, and these individual images have important research value. For research purposes, it is often important to first determine the type of objects represented in a painting. However, the mural painting environment makes datasets difficult to collect, and long-term exposure leads to underlying features that are not distinct, which makes this task challenging. This study proposes a convolutional neural network model based on the classic AlexNet network model and combines it with feature fusion to automatically classify ancient mural images. Due to the lack of large-scale mural datasets, the model first expands the dataset by applying image enhancement algorithms such as scaling, brightness conversion, noise addition, and flipping; then, it extracts the underlying features (such as fresco edges) shared by the first stage of a dual channel structure. Subsequently, a second-stage deep abstraction is conducted on the features extracted by the first stage using a two-channel network, each of which has a different structure. The obtained characteristics from both channels are merged, and a loss function is constructed to obtain the classification result. This approach improves the model's robustness and feature expression ability. The model achieves an accuracy of 84.24%, a recall rate of 84.15%, and an F1-measure of 84.13% when applied to a constructed mural image dataset. Compared with the AlexNet model and other improved convolutional neural network models, the proposed model improves each evaluation index by approximately 5%, verifying the rationality and effectiveness of the model for automatic mural image classification. The mural classification model proposed in this paper comprehensively considers the influences of network width and depth and can extract rich details from mural images from multiple local channels. An effective classification method could help researchers manage and protect mural images in an orderly fashion and quickly and effectively search for target images in a digital mural library based on a specified image category, aiding mural condition monitoring and restoration efforts as well as archaeological and art historical research.  相似文献   

Comparison of Haptic and Biometric Properties,Bacterial Load,and Student Perception of Fixative Solutions: Formaldehyde Versus Chilean Conservative Fixative Solution with and without Formaldehyde in Pig Kidneys     

Marianne Skopnik-Chicago  Katherine Poblete-Cordero  Natali Zamora  Roberto Bastías  Pablo A. Lizana 《Anatomical sciences education》2021,14(6):836-846

One of the most widely used solutions to fix and preserve organic tissues is formaldehyde, despite reservations regarding its toxicity and the fact that formaldehyde-embalmed bodies lose their original characteristics. Anatomy laboratories have been replacing formaldehyde with solutions that retain the characteristics of fresh tissue. For this purpose, alternative solutions with a very low concentration of formaldehyde or without any formaldehyde have been analyzed. The objective of this study was to compare biometry, coloration, haptic properties, and bacterial load on animal specimens (pig kidneys) embalmed with formaldehyde, and with Chilean Conservative Fixative Solution with and without formaldehyde (formaldehyde chCFS and formaldehyde-free chCFS). Also, the perception of health and biological science students toward specimens treated with different solutions was assessed. The results indicated that there were no significant differences in specimens’ retraction, or bacterial load. Students showed a preference for organs embalmed in formaldehyde chCFS and formaldehyde-free chCFS; indicating that with these treatments they could better visualize structures and that the prosections had greater flexibility and the colors were more similar to those of fresh tissue. Additionally, students recommended the material embalmed in formaldehyde chCFS and formaldehyde-free chCFS for anatomy learning. In contrast, students indicated that formaldehyde-fixation negatively affected their practical experience. In conclusion, embalming with formaldehyde chCFS or formaldehyde-free chCFS provides an advantageous practical experience over the use of formaldehyde and may be an alternative to replace the use of formaldehyde in anatomy laboratories.  相似文献   

基于语料库的动态词群建构     

冯文贺 《河南科技学院学报》2014,(9):47-50

提出一个以大规模语料库为资源提取材料,以词汇集为语义成分表达方式的动态词群建构方法,其维度特征值的提取不但具有客观性,而且操作简易。维度特征值用词汇集的方式表示特征取值范围,可以避免传统的义素概括性过强、词汇个性表现不足的缺陷。这种方法有利于面向应用的大规模动态词群的建构。  相似文献   

Subspace design of low-rank estimators for higher-order statistics     

Ivan Bradaric  Athina P. Petropulu  Konstantinos I. Diamantaras 《Journal of The Franklin Institute》2002,339(2):161-187

Higher-order statistics (HOS) are well known for their robustness to additive Gaussian noise and ability to preserve phase. HOS estimates, on the other hand, have been criticized for high complexity and the need for long data in order to maintain small variance. Since rank reduction offers a general principle for reduction of estimator variance and complexity, we consider the problem of designing low-rank estimators for HOS. We propose three methods for choosing the transformation matrix that reduces the mean-square error (MSE) associated with the low-rank HOS estimates. We also demonstrate the advantages of using low-rank third-order moment estimates for blind system estimation. Results indicate that the full rank MSE corresponding to some data length N can be attained by a low-rank estimator corresponding to a length significantly smaller than N.  相似文献   

中国家用电器产品市场扩展特征研究     

何山  胡树华 《科研管理》2003,24(1):98-102

本文以我国家用电器产品为例，通过采用Logistic模型来描述在产品成长期各产品的市场扩展特征，比较各产品的参数差异，发现其中的规律性，为企业相关产品的市场扩展研究提供科学依据。  相似文献   

时间——引文分布特征下学者P指数研究     

张玲玲  蔺梅芳 《现代情报》2019,39(1):169-177

本次研究在P指数基础上，提出了时间——引文分布下学者学术评价P_y指数。具体而言，基于文献引文分布，结合文献被引频次阈值、文献被引半衰期阈值，构建时间——引文分布下的论文分区，即普通论文、潜力论文、热门论文、经典论文。根据4种分区论文影响力差异性，按照普通论文、潜力论文、热门论文、经典论文影响力递增原则，设计论文被引频次递增权值，提出P_y公式。以CNKI平台2000-2017年图情领域核心论文被引频次前100位作者数据进行实证分析，讨论P_y指数表现。结果表明：P_y指数能从论文本身的价值与影响去反映学者的学术成就，凸显优质论文相比普通论文所带来的更强的学术肯定意义；P_y指数区分度、灵敏度、公平公正性、有效性与科学性方面较H指数、P指数表现更佳。  相似文献