Currently, the electrical system in Argentina is working at its maximum capacity, decreasing the margin between the installed power and demanded consumption, and drastically reducing the service life of transformer su...Currently, the electrical system in Argentina is working at its maximum capacity, decreasing the margin between the installed power and demanded consumption, and drastically reducing the service life of transformer substations due to overload (since the margin for summer peaks is small). The advent of the Smart Grids allows electricity distribution companies to apply data analysis techniques to manage resources more efficiently at different levels (avoiding damages, better contingency management, maintenance planning, etc.). The Smart Grids in Argentina progresses slowly due to the high costs involved. In this context, the estimation of the lifespan reduction of distribution transformers is a key tool to efficiently manage human and material resources, maximizing the lifetime of this equipment. Despite the current state of the smart grids, the electricity distribution companies can implement it using the available data. Thermal models provide guidelines for lifespan estimation, but the adjustment to particular conditions, brands, or material quality is done by adjusting parameters. In this work we propose a method to adjust the parameters of a thermal model using Genetic Algorithms, comparing the estimation values of top-oil temperature with measurements from 315 kVA distribution transformers, located in the province of Tucumán, Argentina. The results show that, despite limited data availability, the adjusted model is suitable to implement a transformer monitoring system.展开更多
Extreme value theory provides methods to analyze the most extreme parts of data. We used the generalized extreme value (GEV) distribution to predict the human lifespan in the world and Japan. The diagnostic plots, whi...Extreme value theory provides methods to analyze the most extreme parts of data. We used the generalized extreme value (GEV) distribution to predict the human lifespan in the world and Japan. The diagnostic plots, which assessed the accuracy of the GEV model, were fitted to the human lifespan, validating the model. The human lifespan in the world and Japan had shape parameters of ?0.1623 and ?0.2949 and had an upper limit. The calculated upper limit in the world was 128.7 years. The world’s oldest record holder, Jeanne Calment’s age of 122.45 years, was close to the 260-year return level and was far from the calculated upper limit. The calculated upper limit in Japan was 120.4 years. Japan’s oldest record holder, Kane Tanaka’s age of 119 years in 2022, was the 500-year return level and was close to the upper limit. In the world, achieving the calculated limit was difficult, but the human lifespan will soon reach the upper limit in Japan.展开更多
Oxidative stress has been strongly associated with Parkinson disease (PD) aetiology. We investigated the effects of blueberry extract (BBE) supplementation on α-synuclein induced phenotypes in a Drosophila melanogast...Oxidative stress has been strongly associated with Parkinson disease (PD) aetiology. We investigated the effects of blueberry extract (BBE) supplementation on α-synuclein induced phenotypes in a Drosophila melanogaster model of PD. Enhanced α-synuclein expression in D. melanogaster dopaminergic (DA) neurons can reduce lifespan and we have performed longevity assays to measure the effects of BBE on D. melanogaster survival. Flies expressing α-synuclein in their DA neurons fed BBE had up to an 8 day, or 15%, greater median lifespan than those fed a standard control diet. In addition, BBE improved α-synuclein-induced developmental defects in the Drosophila eye. Our biometric analyses revealed that individuals fed BBE had less atypical ommatidia as well as an increased number of mechanosensory bristle cells than those fed a control diet. We propose that BBE, rich in naturally occurring antioxidants, promotes the survival of neurons in tissues with increased levels of α-synuclein through a protective cell survival mechanism.展开更多
为了研究频域法中的应力幅值概率密度函数(Probability Density Function,PDF)模型在随机振动疲劳寿命评估过程中的适用性,首先介绍常用的5种频域法模型,接着设置由不同谱宽系数、中心频率和功率谱密度(Power Spectral Density,PSD)谱...为了研究频域法中的应力幅值概率密度函数(Probability Density Function,PDF)模型在随机振动疲劳寿命评估过程中的适用性,首先介绍常用的5种频域法模型,接着设置由不同谱宽系数、中心频率和功率谱密度(Power Spectral Density,PSD)谱值组合的限带白噪声应力功率谱。在此基础上利用傅里叶逆变换得到对应的时域信号,并将频域法模型计算得到的应力幅值概率密度函数与模拟的时域信号经过雨流循环计数得到的结果进行对比,评估各种频域模型的适用性和精度。结果表明,在整个带宽范围内,ZhaoBaker模型和Dirlik模型都有较高的准确性和适用性,Weibull模型在模拟小谱宽系数(ε<0.15)的单峰谱和谱宽系数大于0.6的宽带PSD时拥有不错的精度;频域模型的精度误差都随中心频率和谱值的增加有不同程度的下降。展开更多
文摘Currently, the electrical system in Argentina is working at its maximum capacity, decreasing the margin between the installed power and demanded consumption, and drastically reducing the service life of transformer substations due to overload (since the margin for summer peaks is small). The advent of the Smart Grids allows electricity distribution companies to apply data analysis techniques to manage resources more efficiently at different levels (avoiding damages, better contingency management, maintenance planning, etc.). The Smart Grids in Argentina progresses slowly due to the high costs involved. In this context, the estimation of the lifespan reduction of distribution transformers is a key tool to efficiently manage human and material resources, maximizing the lifetime of this equipment. Despite the current state of the smart grids, the electricity distribution companies can implement it using the available data. Thermal models provide guidelines for lifespan estimation, but the adjustment to particular conditions, brands, or material quality is done by adjusting parameters. In this work we propose a method to adjust the parameters of a thermal model using Genetic Algorithms, comparing the estimation values of top-oil temperature with measurements from 315 kVA distribution transformers, located in the province of Tucumán, Argentina. The results show that, despite limited data availability, the adjusted model is suitable to implement a transformer monitoring system.
文摘Extreme value theory provides methods to analyze the most extreme parts of data. We used the generalized extreme value (GEV) distribution to predict the human lifespan in the world and Japan. The diagnostic plots, which assessed the accuracy of the GEV model, were fitted to the human lifespan, validating the model. The human lifespan in the world and Japan had shape parameters of ?0.1623 and ?0.2949 and had an upper limit. The calculated upper limit in the world was 128.7 years. The world’s oldest record holder, Jeanne Calment’s age of 122.45 years, was close to the 260-year return level and was far from the calculated upper limit. The calculated upper limit in Japan was 120.4 years. Japan’s oldest record holder, Kane Tanaka’s age of 119 years in 2022, was the 500-year return level and was close to the upper limit. In the world, achieving the calculated limit was difficult, but the human lifespan will soon reach the upper limit in Japan.
文摘Oxidative stress has been strongly associated with Parkinson disease (PD) aetiology. We investigated the effects of blueberry extract (BBE) supplementation on α-synuclein induced phenotypes in a Drosophila melanogaster model of PD. Enhanced α-synuclein expression in D. melanogaster dopaminergic (DA) neurons can reduce lifespan and we have performed longevity assays to measure the effects of BBE on D. melanogaster survival. Flies expressing α-synuclein in their DA neurons fed BBE had up to an 8 day, or 15%, greater median lifespan than those fed a standard control diet. In addition, BBE improved α-synuclein-induced developmental defects in the Drosophila eye. Our biometric analyses revealed that individuals fed BBE had less atypical ommatidia as well as an increased number of mechanosensory bristle cells than those fed a control diet. We propose that BBE, rich in naturally occurring antioxidants, promotes the survival of neurons in tissues with increased levels of α-synuclein through a protective cell survival mechanism.
文摘为了研究频域法中的应力幅值概率密度函数(Probability Density Function,PDF)模型在随机振动疲劳寿命评估过程中的适用性,首先介绍常用的5种频域法模型,接着设置由不同谱宽系数、中心频率和功率谱密度(Power Spectral Density,PSD)谱值组合的限带白噪声应力功率谱。在此基础上利用傅里叶逆变换得到对应的时域信号,并将频域法模型计算得到的应力幅值概率密度函数与模拟的时域信号经过雨流循环计数得到的结果进行对比,评估各种频域模型的适用性和精度。结果表明,在整个带宽范围内,ZhaoBaker模型和Dirlik模型都有较高的准确性和适用性,Weibull模型在模拟小谱宽系数(ε<0.15)的单峰谱和谱宽系数大于0.6的宽带PSD时拥有不错的精度;频域模型的精度误差都随中心频率和谱值的增加有不同程度的下降。