船用烟气余热S-CO_(2)布雷顿循环发电系统性能分析

开展船舶主机不同负荷工况下的S-CO_(2)布雷顿循环余热系统热力学特性和效能分析是其实现工程应用的必要环节。本文通过性能分析确定系统热力学参数对净输出功率和平准化能源成本的影响变化趋势,最佳运行参数范围以及系统关键热力学参数。通过主机典型负荷工况下的效能评估,分析集成S-CO_(2)再压缩布雷顿循环余热发电系统后的船舶节能减排效益。结果表明:主压缩机入口压力和压比对整个余热发电系统热力学性能和经济性影响最为显著,可调节这2个关键热力学参数以确保系统在船舶主机不同负荷下获得良好系统性能;集成该余热发电系统后,MAN8S90ME-C10.2型主机系统热效率最高可提高0.91%,燃油消耗量平均每年可减少51 t,NO_(2)和CO_(2)的排放量每年可分别减少2.28 t和760 t。

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。

气象因子相对危险度在电网用电负荷预测中的应用

[目的]准确高效的短期用电负荷预测是保证电力系统安全可靠运行的前提,也是电网合理安排发电计划的依据,因此研究气象与用电负荷的关系对负荷预测的工作具有重要意义。[方法]以石家庄为例,利用国网河北省某电力公司提供的2013年1月1日至2021年12月31日逐15 min用电负荷资料,以及对应的石家庄站气象观测资料,分析日用电负荷峰值的时间变化特征,重点分析了当日用电负荷峰值较前1日用电负荷峰值变幅超过10%的样本对应的气象条件。采用Spearman秩相关方法分析石家庄日用电负荷峰值与前1日气象要素的相关关系,得到相关性显著的气象要素。利用平滑曲线拟合法绘制各相关性显著的气象要素对次日用电负荷峰值的响应曲线,分析得出随着各气象要素的变化日用电负荷峰值变化趋势以及响应阈值。按不同阈值区间,基于泊松分布计算得出石家庄地区各气象要素对日用电负荷峰值变化的相对危险度,进而揭示石家庄地区各气象要素在不同阈值区间发生单位变化造成的日用电负荷峰值的变化幅度,即不同气象要素的变化对日用电负荷峰值变化的定量影响。[结果]以气温为例,当日平均气温、日最高气温、日最低气温高于阈值时,每上升1℃,次日用电负荷峰值的相对危险度分别增加2.25%、1.92%、2.07%;低于阈值时,每上升1℃,次日用电负荷峰值的相对危险度分别减少0.62%、0.57%、0.60%。[结论]基于不同气象要素对石家庄地区日用电负荷峰值的相对危险度提出1种次日用电负荷峰值的预测方法,利用2022年逐日用电负荷和气象资料进行检验,发现预测效果可以满足日常电力气象服务需求。

Change Trend of Chinese Urban Residents' Food-nitrogen Consumption

Change trend of Chinese urban residents＇ per capita food-nitrogen annual consumption from 1981 to 2007 was analyzed and predicted by using ARIMA time-series model in order to reveal the change of urban food-nitrogen consumption during the China＇s urbanization process.Results showed that after 1980s,the annual consumption of Chinese urban residents＇ food-nitrogen had a change trend of ＂ increase-decrease-increase＂ and generally presented as a slight increasing trend;With the acceleration of rapid economic development and urbanization process,Chinese urban residents＇ food-nitrogen consumption will still keep a rising trend in future,and also has a large rising space.

关坪亚洲象食物源基地内亚洲象活动特点及与地区水热条件变化关系研究

通过对比2005—2012年间关坪亚洲象食物源基地的亚洲象活动记录和同期气象观测数据,对食物源基地中亚洲象活动规律与当地降雨、温度变化间的关系进行分析。结果显示,进入食物源基地的亚洲象数量与年份增加呈正相关关系(r_(s)=0.643),食物源基地正吸引越来越多的亚洲象来此觅食;进入基地的亚洲象活动次数随年降雨量的降低而增加,主要是因为亚洲象独立个体活动次数的增加。气候变化对亚洲象活动规律有潜在影响,建议未来在当地开展更加深入的气候和森林物候监测,以更合理地解释当地亚洲象的活动规律和行为改变。

基于SGA-RF算法的农业土壤镉浓度反演研究

在农业土壤重金属高光谱检测领域,土壤镉元素近红外光谱的高维、高冗余特性会严重影响高光谱反演模型的准确性和稳定性。为了解决上述问题,本文提出一种基于斯皮尔曼相关分析的遗传随机森林特征选择算法(SGA-RF)。该算法首先对初始特征集合使用基于斯皮尔曼相关分析的特征预选方法,筛选出大量冗余波段,保留与镉元素相关性最强的特征波段;其次在特征精选阶段,提出一种基于随机森林的适应度函数评估方法,该方法充分结合遗传算法强大的全局搜索能力和随机森林算法较高的反演能力,提高了对相似个体的区分能力,获得具有最小冗余度和最大区分性的最优特征波段子集。为了验证所提算法的有效性,选取青岛市大沽河流域具有代表性的124个土壤样品为实验对象,利用SGA-RF算法将原始2 051个波段优选至37个最具代表性的敏感波段,并与现有特征选择算法所建模型进行对比分析。试验结果表明,该特征选择方法与随机森林回归模型相结合具有较低的预测均方根误差(0.060 1),较高的相关系数(0.950 2)和预测相对分析误差(2.03)。作为应用可见/近红外光谱技术定量反演农业土壤镉浓度的重要步骤,SGA-RF算法以较少的敏感波段达到了较高的反演效果,可为监测土壤重金属污染情况提供一定的理论依据。

宝鸡市降水和径流的分形特征与R/S分析

首先用肯德尔秩次相关检验和斯波曼秩次相关检验对宝鸡市的降水序列及主要河流的年径流序列作了趋势性分析,再用R/S分析法对各序列的长程相关性进行了判别,并计算了各序列的豪斯道夫维数。结果表明:除了冬季降水外,宝鸡市的降水和径流都存在着不同程度的减少趋势;且降水和径流序列都存在着长程相关性,即未来各序列的趋势仍将持续下去;豪斯道夫维数的计算表明各序列的复杂程度是不相同的。

解决冲突证据合成问题的改进D-S证据理论算法

冲突证据在证据合成时会造成合成结果与直觉相悖的现象.为解决冲突证据合成问题,分析了传统D-S证据理论的基本性质及其改进方法的不足,提出一种结合斯皮尔曼等级相关系数的证据合成方法.该方法首先计算出证据之间的相关系数并且得到相关性矩阵;然后根据相关性矩阵构造修正系数来折扣基本可信度分配函数;最后利用D-S证据组合规则对修正后的证据进行合成.经典数值算例结果表明:改进后的算法具有更高的目标辨识率,并且此方法计算过程简捷,适用范围广,有效解决了证据间的高度冲突问题.

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.

Spatio-temporal Distribution Characteristics and Environmental Impact Factors of Lung Cancer Mortality: A Case Study of Yuhui District in Bengbu City, China

Among cancers, lung cancer is the most common cause of death in China. For the prevention and control of lung cancer, it is necessary to investigate the spatial and temporal distribution of lung cancer mortality, as well as the changes in the trend and the affecting mechanism. Based on statistics and auto-correlation analysis, this paper studied the spatial and temporal distribution of lung cancer mortality in Yuhui District, Bengbu, Huaihe River Basin, from 2017 to 2020. In addition, Spearman’s Rank Correlation Assessment Model and Geographic Detector Model were used to examine the relationship between environmental factors and lung cancer mortality to identify impact factors and their mechanisms. The findings indicated that: 1) from the characteristics of temporal distribution, the number of lung cancer deaths exhibited a linear growth tendency, with the highest mortality in winter;2) from the characteristics of spatial distribution, lung cancer mortality showed a strong spatial agglomeration form, concentrating on two clustering areas, located in the old city and the central city of Bengbu, near the Huaihe River;3) from the point of view of the whole research area, there were 15 impact factors with significant correlation in the built and natural environment factors. The significant impacting factors in the built environment included land use, road traffic, spatial form and blue-green space, which could indirectly affect lung cancer mortality, while air pollution and temperature constituted the significant impacting factors in the natural environment;4) the influence of screened environmental factors on lung cancer mortality was different. Spatial stratified heterogeneity assessment, the interaction among environmental factors demonstrated statistical significance, it was found that the interaction between environmental factors in pairs had a significant enhancement effect on lung cancer mortality. To some extent, urban planning and policies could reduce lung cancer mortality.

Projecting impact of CPEC on Pakistan’s electric power crisis

The commencement of China–Pakistan Economic Corridor has led to the appreciation of Pakistan’s economic outlook from 5.4%to 5.8%by the World Bank.The upgraded outlook is a welcome sign but it is still trivial,essentially attributable to the electric power crisis,which approximately trims 2%of Pakistan’s economic growth annually.Almost 60%of the CPEC(China–Pakistan Economic Corridor)funds are directed at Pakistan’s energy sector,hence,demanding careful attention of both researchers and policy analysts alike.The study is based upon a meta-analytic review of literature concerning CPEC and Pakistan’s energy sector.The results of the study demonstrate that CPEC is an easing agent for Pakistan’s energy crisis(82.30%).The results also highlight points of concern,including inadequate planning(47%),dilapidated electricity distribution system causing losses(64.7%),and an unsustainable energy mix(64.7%).The study further validates the findings via Spearman’s Rho-Correlation.The rρvalue for the possible“resolution of Pakistan’s energy crisis”is 0.5426 achieving a significance level of 98%and a corresponding p-value of 0.0252.The significant negative rρvalue attained is−0.4894 which establishes the fact that lack of planning can hinder the energy crisis resolution.

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.

长江经济带省际贸易隐含水-能-碳耦合关系研究

采用环境投入产出模型计算长江经济带省际贸易中虚拟水、隐含能及隐含碳流量,进一步结合Spearman等级相关系数研究分地区与分部门间的水能碳耦合关系。结果表明:水、能和碳在地区间和部门间均呈显著相关关系,其中第二产业和隐含能碳相关性最强。虚拟水、隐含能和隐含碳调出调入中,江苏、浙江为关键省份,农业、建筑业和电力、热力、燃气及水的生产供应业是关键部门。深入研究隐含水能碳耦合特征,从贸易平衡视角将长江经济带11省市分为3类,发现隐含水能碳压力存在从发达地区转入欠发达地区的环境不公平现象。长江经济带应注重关键地区和关键部门节水节能减碳目标落实,推动产业结构低碳化、绿色化发展,同时加快形成区域协同治理体系。

App Store Analysis: Using Regression Model for App Downloads Prediction

App store provides rich information for software vendors and customers to understand the market of mobile applications. However, app store analysis don’t consider some vital factors such as version number, app description and app name currently. In this paper we propose an approach that App Store Analysis can be used to predict app downloads. We use data mining to extract app name and description and app rank information etc. from the Wandoujia App Store and AppCha App Store. We use questionnaire and sentimentanalysis to quantify some app nonnumeric information. We revealed strong correlations app name score, app rank, app rating with app downloads by Spearman’s rank correlation analysis respectively. Finally, we establish a multiple nonlinear regression model which app downloads defined as dependent variable and three relevant attributes defined as independent variable. On average, 59.28 % of apps in Wandoujia App Store and 66.68 % of apps in AppCha App Store can be predicted accurately within threshold which error rate is 25 %. One can observe the more detailed classification of app store, the more accurate for regression modeling to predict app downloads. Our approach can help app developers to notice and optimize the vital factors which influence app downloads.

山西黄河湿地植被优势种群种间关系

在样方调查的基础上,应用2×2列联表的Fisher精确检验、Pearson相关系数和Spearman秩相关系数检验了山西黄河湿地植被优势种群的种间关系,分别测定了24个优势种,共73个种对的种间关联。结果表明:(1)2×2列联表的精确检验共有33个种对为正关联,4个种对为负关联;Pearson相关系数有16个种对呈正相关,没有种对出现负关联;Spearman秩相关系数有40个种对呈正相关,4个种对为负关联。(2)2×2列联表的精确检验不能精确反映种对间的数量变化关系,只能反映种对间关联与否;应用Pearson相关系数和Sperman秩相关检验可帮助刻划种对间的数量变化关系。(3)依Spearman秩相关系数的半矩阵图将24个优势种分为旱生、中生、湿生、水生4个生态种组,各生态种组内的种对具有相同的资源利用方式和生态要求。

北沟林场天然次生林主要乔木树种种间关系分析

采用χ2检验、Ochiai关联指数、Pearson相关分析和Spearman秩相关分析法对北沟林场天然次生林11种乔木的种间联结和相关性进行了研究,结果表明:所有种对中,呈显著相关和极显著相关的种对数所占比例较少,多数种对间关联程度未达到显著水平,说明林场多数乔木树种间关系不紧密,未形成明显的总体联结性,群落处于相对稳定状态;种间关系分析中,Spearman秩相关分析结果比χ2检验、Ochiai关联度和pearson相关分析的结果灵敏度要高;依照分析结果,结合植物种群的生物学和生态适应特征,将北沟林场天然次生林群落中11种乔木树种划分为3个生态种组,同一生态种组内物种资源利用方式和生态要求相似,联结紧密,而不同组间联结较为松散。

新疆艾比湖湿地植被优势种种间关系研究

于2007年8月,采用样方法对新疆艾比湖湿地植物进行了调查,并应用χ2检验、Pearson相关分析、Spearman秩相关分析对艾比湖地区野生湿地植物群落不同生活型主要种的种间关系进行了检验,共分析了19个种,共171个种对间的相关关系。结果表明,艾比湖湿地植物的种间关系中呈显著或极显著相关的种对数占种对数量的22.2%,种间联结主要为正关联。其中,同种生活型层内,草本层种间关联系数较大;不同生活型内,灌木层与草本层的优势种种间关联系数较大。调查情况表明,艾比湖湿地群落处于退化状态,群落内植物种以草本、灌木为主。其中,灌木对于该保护区内群落结构的保持有重要的作用,对草本层的生存产生有利的影响,群落内小斑块多呈灌—草结构。

承德县人工油松林林下草本植物种间关系研究

为研究林下草本层植物种间联结性,以承德县人工油松林林下草本植物为研究对象,采用χ2检验、Pearson相关分析和Spearman秩相关分析检验了35个物种595个种对间的关联性,研究结果表明:在表征种间关联方面,Spearman秩相关分析较χ2检验、Pearson相关分析灵敏度高;3种检验方法的一致结果为:负相关的种对数远多于正相关,而极显著和显著相关的种对数所占比例较低,大多数种间关系松散,独立性相对较强,群落还处于演替之中;种对间的正相关是由于它们的生态适应性相近,是生态位重叠的表现;而种对间的负相关正是生态位分离的结果。

中国农产品贸易调整的能力与成本研究

文章利用入世后中国农产品贸易数据,实证分析了进、出口产品结构的现状和演化。研究表明中国进口产品结构适应世界市场变动趋势;出口则未遵照世界需求及时调整,调整能力明显低于进口。把国际市场滞后一期,中国出口调整能力依然较弱且显著;进口调整能力也要弱于当年的进口调整。指数表征中国具有贸易调整的可能性,中国可通过调整农产品贸易结构,提高国内与国际市场的对接吻合程度,促进农产品贸易条件改善。

相关系数在脉冲噪声环境下的稳健性综述

作为相关分析的重要工具,相关系数在众多科学与技术领域中都得到了广泛的研究和应用.基于文献中两种常用的二元混合高斯模型,本文回顾和对比了5种相关系数分别在单通道以及双通道中存在脉冲噪声时的稳健性.定量的研究结果表明,在脉冲噪声环境下,文献中最为常见的皮尔逊积矩相关系数性能急剧恶化.而另外4种相关系数则在两种噪声模型下均表现出良好的抗干扰能力.