Statistical analysis on the influence of mechanical parameters in the vibration of pylons

We present a statistical investigation of the degree of influence that assumptions made in relation to the mechanical parameters of a pylon have on its ground-induced vibrations.The study is set up by using as a key kinematic variable the displacement at the top of a reference,a stand-alone pylon with a uniform cross-section and fixity at its base.Next,statistics are produced using a dimensionless displacement ratio defined between the‘parental’and the‘subsidiary’cases,the latter defined for the pylon(a)resting on compliant soil,(b)having an attached top mass,and(c)being non-uniform with height.Furthermore,two materials are examined,namely,steel and reinforced concrete(R/C).More specifically,this displacement ratio is independent of the excitation and plays the role of a transfer function between the base and the top of the pylon.Both horizontal and vertical motions are considered,and the equations of motion are solved in the frequency domain.The ensuing statistical analysis is conducted for the following parameter combinations:(a)pylon founded on soft,intermediate,and stiff soil;(b)low,intermediate,and high-mass ratios of the attached mass to the pylon′s mass;(c)a constant and quadratic degree of pylon tapering with height.Spearman correlation coefficients are calculated for all the above combinations to arrive at statistical results that establish validity bounds and quantify the degree of influence of each assumption on the pylon′s response.

基于Logistic回归的古代玻璃制品化学成分分析和研究

文章主要通过研究玻璃含有的不同化学成分,分析和鉴别古代的玻璃制品。首先分析了现有玻璃文物的数据,利用Spearman’s rank correlation coefficient和卡方检验表面分化、纹饰、颜色和玻璃类型之间的联系,采用Logistic回归鉴别未知文物,分析其所属的类型,并分析了分类结果的灵敏度。通过分析可知,文章采用的分类方法,能较好地通过化学成分对玻璃进行分类。

Guided Wave Based Damage Detection Method for Aircraft Composite Structures under Varying Temperatures

Guided waves based damage detection methods using base signals offer the advantages of simplicity of signal generation and reception,sensitivity to damage,and large area coverage;however,applications of the technology are limited by the sensitivity to environmental temperature variations.In this paper,a Spearman Damage Index-based damage diagnosis method for structural health condition monitoring under varying temperatures is presented.First,a PZT sensor-based Guided wave propagation model is proposed and employed to analyze the temperature effect.The result of the analysis shows the wave speed of the Guided wave signal has higher temperature sensitivity than the signal fluctuation features.Then,a Spearman rank correlation coefficient-based damage index is presented to identify damage of the structure under varying temperatures.Finally,a damage detection test on a composite plate is conducted to verify the effectiveness of the Spearman Damage Index-based damage diagnosis method.Experimental results show that the proposed damage diagnosis method is capable of detecting the existence of the damage and identify its location under varying temperatures.

Characteristics of Ambient Air Quality in the Central Urban Area of Western Guizhou in the Past Five Years

Air is an important condition for human activities and survival,and its quality is closely related to the quality of life and level of health for the people.In recent years,the problem caused by air quality has become one of the main problems that endanger human health and restrict economic development,which has been widely concerned.In this paper,the air quality status and its changing trend were analyzed by using the methods of the comprehensive index of ambient air quality and Spearman s rank correlation coefficient,based on the hourly pollutant concentration data of five national ambient air quality monitoring stations in the central urban area of Liupanshui City,Guizhou Province from January 1,2015 to December 31,2019.The results showed that the concentration of air pollutants in the atmosphere in the past five years showed a downward trend in the central urban area of Liupanshui City.During 2018-2019,the air quality has been up to the standard for two consecutive years,and it was developing to a higher quality direction.The air quality was better in summer half year than in winter half year.In one year,the air quality was the best in June and the worst in February.The air quality was the best at 07:00 and the worst at 21:00 every day.The air quality in the east and the west of the city was better than that in the middle.In most years,the activities,making and burning paper to resemble money as an offering sacrifices to gods or ancestors in Zhongyuan Festival,caused serious pollution.

An Automatic Monitoring and Alarming Method for the Power Supply of Weather Radars

As weather radar stations require headroom environment to operate,they were mostly built on highlands which are usually unattended.The mains supply is relatively poor,and the risk of radar stoppages due to power outage is therefore ever-present.As such,the radar construction program is used to build a complementary security video monitoring system.By collecting monitoring images of the regulated power supply in real-time from power supply auto transfer systems in distribution rooms and radar transceiver rooms,using Spearman’s rank correlation coefficient to analyse pixel variation trends,and supplementing statistical analysis of pixel characteristics difference to eliminate misjudgments resulting from low image contrast in special scenarios,a software can be developed through C#.It has the function of automatically monitoring mains supply and alerting staff on duty to handle the power outage in a timely manner via text message so that any potential risk is neutralised before it can cause damage.This monitoring and auto-alerting approach is generally applicable to unattended rooms with large amounts of electronical equipment.

Temporary Crops in the Brazilian Agricultural Frontier

Food production remains one of the main challenges for humankind in this century, and Brazil is one of the largest food-producing countries that have yet some land for economically or technically profitable farming expansion. Moreover, knowing which areas constitute the Brazilian agricultural frontier is crucial for improving public policies and logistics infrastructure decisions. Data from the Brazilian Institute of Geography and Statistics from 1995 to 2019 were used in this study. We aimed to map and measure the expansion of agricultural areas in Brazil from 1995 to 2019 for temporary crops according to their mesoregions. We used a four-stage methodology, compared the results of two agglomerative clustering methods, and identified similar mesoregions based on their share trends in the Brazilian agricultural seeded area. Some mesoregions had higher positive trend values for their share of the Brazilian agricultural seeded area: Mato-grossense North (MT), Mato-grossense Northeast (MT), Mato Grosso do Sul Southwest (MS), Goiano South (GO), Extreme West Bahia (BA), Maranhense South (MA), Piauiense Southwest (PI), and Tocantins Eastern (TO). As a second leading group, the Paranaíba Upstream (MG), São José do Rio Preto (SP), Mato-grossense Southeast (MT), and Goiano East (GO), must be emphasized. Further research is recommended, including extending the study to permanent crops and applying top-down analysis targeting microregions or municipalities in the identified mesoregions.