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机械制造工厂噪声污染的控制对策 总被引:1,自引:0,他引:1
分析了机械制造工厂的噪声来源,并针对其噪声源特点,提出了降低噪声的技术措施和行政管理措施。 相似文献
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李利 《防灾科技学院学报》2006,8(2):112-114
将中国机械史及国情教育融入机零机原课教学中,无疑对加强和改进大学生思想政治教育,能起到很好的推动作用.中国机械史,内涵丰富;国情教育,贴近实际;是提高大学生素质的重要内容. 相似文献
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A palaeoecological study was conducted to investigate past environmental conditions and vegetation dynamics around the southwestern Ljubljana Moor. In order to find potential regularities and/or dependencies among co-existent plant species through time, different machine learning methods were applied to pollen records from the cores taken at Bistra and Ho?evarica. The data comprised relative pollen frequencies of the most common plant genera/families at particular core depths that correspond to particular ages in the Early and Mid Holocene periods. The applied methods include equation discovery and hierarchical clustering. Both methods have found plausible and explainable relationships among identified plant genera/families. 相似文献
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Longitudinal behavioral data generally contains a significant amount of structure. In this work, we identify the structure
inherent in daily behavior with models that can accurately analyze, predict, and cluster multimodal data from individuals
and communities within the social network of a population. We represent this behavioral structure by the principal components
of the complete behavioral dataset, a set of characteristic vectors we have termed eigenbehaviors. In our model, an individual’s
behavior over a specific day can be approximated by a weighted sum of his or her primary eigenbehaviors. When these weights
are calculated halfway through a day, they can be used to predict the day’s remaining behaviors with 79% accuracy for our
test subjects. Additionally, we demonstrate the potential for this dimensionality reduction technique to infer community affiliations
within the subjects’ social network by clustering individuals into a “behavior space” spanned by a set of their aggregate
eigenbehaviors. These behavior spaces make it possible to determine the behavioral similarity between both individuals and
groups, enabling 96% classification accuracy of community affiliations within the population-level social network. Additionally,
the distance between individuals in the behavior space can be used as an estimate for relational ties such as friendship,
suggesting strong behavioral homophily amongst the subjects. This approach capitalizes on the large amount of rich data previously
captured during the Reality Mining study from mobile phones continuously logging location, proximate phones, and communication
of 100 subjects at MIT over the course of 9 months. As wearable sensors continue to generate these types of rich, longitudinal
datasets, dimensionality reduction techniques such as eigenbehaviors will play an increasingly important role in behavioral
research.
This contribution is part of the special issue “Social Networks: new perspectives” (Guest Editors: J. Krause, D. Lusseau and
R. James).
An erratum to this article can be found at 相似文献
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此文介绍了旋压成形技术在轴承工艺中的应用、特点.以588909、588911和688808三种轴承为例给旋压成形技术在轴承工艺上的应用提供了实践的依据. 相似文献
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Current liquid flammability classification mainly relies on flash point and its risk is largely dependent on consequence and probability. However, combustions of liquefied marine fuels have their uniqueness, leading to a less consistent with the common classification. This work aims at classifying flammable liquids in compression ignition engines for further safety evaluation. Besides liquid flammability characteristics, flame propagation and aerosol formulation are considered. Two unsupervised machine learning clustering algorithms, k-means and spectral clustering, are applied to the collected liquid compounds database. To consider both cluster cohesion and separation, the global mean silhouette value is used to find the optimal number of clusters and to evaluate the clustering performance. The results show that the spectral clustering outperforms k-means on classifying the risk ratings for all proposed models, while the clustering accuracy of the optimal model has been doubled by employing spectral clustering algorithm. Moreover, principal component analysis and star coordinate diagrams are presented to visualize high dimensional data to 2-D graphs. Finally, the overall liquid safety performance is evaluated by a novel combustion risk index via the weight values determined by the information entropy approach. This index can be used to explore inherently safer fuels in the process industries. 相似文献
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Introduction: In-transport vehicles often leave the travel lane and encroach onto natural objects on the roadsides. These types of crashes are called run-off the road crashes (ROR). Such crashes accounts for a significant proportion of fatalities and severe crashes. Roadside barrier installation would be warranted if they could reduce the severity of these types of crashes. However, roadside barriers still account for a significant proportion of severe crashes in Wyoming. The impact of the crash severity would be higher if barriers are poorly designed, which could result in override or underride barrier crashes. Several studies have been conducted to identify optimum values of barrier height. However, limited studies have investigated the monetary benefit associated with adjusting the barrier heights to the optimal values. In addition, few studies have been conducted to model barrier crash cost. This is because the crash cost is a heavily skewed distribution, and well-known distributions such as linear or poison models are incapable of capturing the distribution. A semi-parametric distribution such as asymmetric Laplace distribution can be used to account for this type of sparse distribution. Method: Interaction between different predictors were considered in the analysis. Also, to account for exposure effects across various barriers, barrier lengths and traffic volumes were incorporated in the models. This study is conducted by using a novel machine-learning-based cost-benefit optimization to provide an efficient guideline for decision makers. This method was used for predicting barrier crash costs without barrier enhancement. Subsequently the benefit was obtained by optimizing traffic barrier height and recalculating the benefit and cost. The trained model was used for crash cost prediction on barriers with and without crashes. Results: The results of optimization clearly demonstrated the benefit of optimizing the heights of road barriers around the state. Practical Applications: The findings can be utilized by the Wyoming Department of Transportation (WYDOT) to determine the heights of which barriers should be optimized first. Other states can follow the procedure described in this paper to upgrade their roadside barriers. 相似文献
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