分类: 统计学 >> 经济统计学 提交时间: 2024-08-17
摘要: 2020年9月22日联合国大会一般性辩论上明确中国将提高国家自主贡献力度,力争于2030年前二氧化碳排放达到峰值,2060年前实现碳中和。然而,过往的社会发展模式致使碳排放量逐年升高,因此必须解决发展与碳减排之间的矛盾。本文对某区域的碳排放量与经济、人口、能源消费量之间的关系进行了研究,并为实现碳达峰与碳中和提供决策支持。为实现这一目标,建立了包括经济指标、人口指标、能源消费量指标和碳排放量指标在内的全面指标体系。对该区域在十二五和十三五时期的碳排放量、经济、人口和能源消费量进行了详细的分析,比较了2010年、十二五和十三五期间的碳排放量总量,并分析了其变化趋势。全面分析了该区域碳排放量与经济、人口、能源消费量之间的关系和相互影响。研判了实现碳达峰与碳中和所面临的主要挑战。首先是能源结构转型其次是技术创新与推广,第三是政策与治理,最后是社会经济转型。建立了区域碳排放量与经济、人口、能源消费量之间的关联模型。使用ARIMA模型进行碳排放量的预测,并考虑到双碳政策和技术进步等因素。运用熵权法对指标进行无量纲化处理,并分析各指标之间的关联程度。由结果预测碳排放量的变化趋势,为制定双碳路径规划提供重要依据。通过kaya模型计算得到碳排放与各因素模型推算出三种情景下碳达峰的具体时间,基准情景、自然情景、雄心情景三者碳达峰时间分别为:2022年、2036年、2021年,为双碳路径规划提供判断依据与支持。本研究的结果对于实现碳减排目标、推动可持续发展具有重要意义。通过深入分析碳排放量与经济、人口、能源消费量之间的关系,以及研判实现碳达峰与碳中和所面临的挑战,制定出针对性的政策和措施,推动区域的可持续发展,实现碳减排目标。
分类: 统计学 >> 经济统计学 提交时间: 2024-08-16
摘要: Based on the energy consumption data of 30 provinces in China from 2000 to 2021, this paper estimates and predicts the total carbon emissions of 30 provinces in China from 2000 to 2035using ARIMA model and BP neural network model. ArcGIS and standard elliptic difference are used to visually analyze the spatio-temporal evolution characteristics, and LMDI model is further used to decompose the driving factors affecting carbon emissions. The results show that: (1) China’s total carbon emissions increased year by year from 2000 to 2035, but the growth rate of carbon emissions decreased gradually; The carbon emission structure is "secondary industry > residents’livelihood > tertiary industry > primary industry". the growth rate of carbon in secondary industry and residents’ livelihood is relatively fast, while the change trend of primary industry and tertiary industry is relatively small. (2) the spatial distribution of carbon emissions in China’s provinces presents a typical "eastern > central > western" and "northern > southern" distribution pattern, with the carbon emission center moving to the northwest; (3) The regions with higher development level of digital economy, industrial structure and new quality productivity have relatively less carbon emissions, with significant group difference effect; (4) Energy consumption intensity effect is the main factor to drive the continuous growth of carbon emissions, per capital GDP and energy consumption structure effect are the main factors to curb carbon emissions, and the impact of industrial structure and population size effect is relatively small. Based on the research conclusions, policy suggestions are put forward from the aspects of energy structure, industrial structure, newquality productivity and digital economy.
分类: 统计学 >> 经济统计学 分类: 能源科学 >> 能源计算与测量 提交时间: 2024-08-16
摘要: 中国碳排放总量占全球的三分之一,如何在2030年前达到碳排放峰值,并在2060年前实现碳中和,保证“双碳”目标的有效实现是当前重要的政策取向。因此,在有效测算和预测各省碳排放的基础上,对时空演变的特征及驱动因素进行分析,对于推进经济高质量发展的同时实现碳减排具有重要意义。本文采用2000—2021年中国30个省份能源耗费数据,基于ARIMA模型和BP神经网络模型,测算并预测了2000—2035年中国30个省份碳排放总量,采用ArcGIS和标准椭圆差对时空演变特征进行了可视化分析,进一步利用LMDI模型对影响碳排放的驱动因素进行了分解。研究结果表明:(1)2000—2035年,我国碳排放总量逐年递增,但碳排放增长率逐渐降低;碳排放结构为“第二产业>居民生活>第三产业>第一产业”,第二产业和居民生活碳的增长速度较快,第一产业和第三产业变化趋势较小;(2)我国各省碳排放的空间分布呈现典型的“东部>中部>西部”,“北部>南部”的分布格局,碳排放中心有向西北移动的趋势;(3)数字经济、产业结构高级化以及新质生产力发展水平较高的地区碳排放相对较少,具有显著的组别差异效应;(4)能源消费强度效应是驱动碳排放不断增长主要因素,人均GDP和能源消费结构效应是抑制碳排放的主要因素,产业结构和人口规模效应的影响相对较小。基于研究结论,从能源结构、产业结构、新质生产力和数字经济等方面提出了政策建议。
分类: 医学、药学 >> 临床医学 提交时间: 2024-08-16
摘要: 生活方式医学(Lifestyle Medicine)起源于 20 世纪 80 年代,是一门涉及医学、营养学、运动科学、流行病学、心理学等多个领域的新兴交叉学科,作为促进公共健康和临床治疗的关键纽带,是所有疾病预防、治疗、康复的重要健康策略。本文系统梳理生活方式医学的定义与内涵、起源与发展、疗效评价工具,发现生活方式医学与中医“治未病”理念高度契合,我国生活方式医学学科发展仍处于起步阶段,尽管在慢性病管理方面已取得一些研究成果,但目前仍缺乏具体化、定量化和规范化的生活方式实施细则、临床指南及评价体系。生活方式医学的中国化仍需结合本土国情,加大国家政策支持力度,建立全国数据监测系统和决策支持系统,注重健康公平性并优化不同地区的卫生资源配置,进一步整合中医药的特色疗法和“简便廉”优势,以推动生活方式医学在慢性病预防与管理领域的应用与推广,提升国民健康水平。
分类: 护理学 >> 护理学 提交时间: 2024-08-15
摘要: 目的 探究超细化综合护理干预在肝内胆管癌术后化疗患者负性情绪中的应用效果。方法 选取我院2023年1月到2024年1月收治的182例肝内胆管癌术后化疗患者作为本次研究对象,采用随机数字表法将其分为对照组(n=91)和试验组(n=91),对照组进行常规护理,试验组在常规护理基础上加上超细化综合护理干预内容,从而比较两组患者干预前后负性情绪、疲乏程度、生活质量以及护理满意度。结果 两组患者经干预后焦虑(SAS)、抑郁(SDS)评分均有显著下降,且试验组SAS、SDS评分均低于对照组(PPPP<0.05)。结论 超细化综合护理干预实施能够帮助肝内胆管癌术后化疗患者改善负性情绪,提高战胜疾病信心,从而减轻癌因性疲乏,提高生存质量与生活质量,通过亲情式细化服务提高患者的满意度。
分类: 医学、药学 >> 临床医学 提交时间: 2024-08-15
摘要: 中国心血管病(CVD)患病率处于持续上升阶段。推算 CVD 现患人数 3.3 亿,其中卒中 1 300 万,冠心病(CHD)1 139 万,心力衰竭(HF)890 万,肺源性心脏病 500 万,心房颤动 487 万,风湿性心脏病 250 万,先天性心脏病 200 万,外周动脉疾病(PAD)4 530 万,高血压 2.45 亿。2021 年中国心脑血管疾病患者出院总人次数为2 764.98 万,占同期出院总人次数(包括所有住院病种)的 15.36%,其中 CVD 1 487.23 万人次,占 8.26%,脑血管病1 277.75 万人次,占 7.10%。CVD 给居民和社会带来的经济负担仍在加重,CVD 防治的拐点尚未到来。
分类: 核科学技术 >> 核科学与技术 提交时间: 2024-08-15
摘要: 熔盐堆是六种第四代反应堆之一,其使用液态核燃料,与常规固态核燃料堆型不一样。为做好堆芯设计管理和核安全监管,有必要对其7Li丰度与核临界参数的关系进行分析。本研究通过参考具有工程实践的熔盐堆进行建模,运用软件仿真模拟计算,分析不同7Li丰度燃料盐对熔盐堆反应性的影响,分析核临界参数变化的规律。通过迭代计算,快速精确找到熔盐堆核临界时的7Li丰度值。最终得出结论,熔盐堆反应性随着燃料盐7Li丰度的增加而增加,且在熔盐堆反应性变化率也与7Li丰度有关。根据本研究分析成果进行深入探讨,从法律法规角度总结相关管理要求,从审管角度提出应该关注的建议要点。
分类: 图书馆学、情报学 >> 图书馆学 提交时间: 2024-08-15
摘要: 随着互联网+时代的来临,学术交流出现了新的发展趋势,非正式交流蓬勃发展,基于虚拟社区的交流更为普及,且学术信息在交流的过程中不断完善。图书馆是构建学术交流平台,提供学术交流服务的重要阵地。文章提出通过收集用户数据,引入用户画像技术,提供更为个性化的学术资源和交流服务,形成包含数据层、画像层、个性化服务层和反馈层的学术交流服务框架,有针对性地优化服务。
分类: 医学、药学 >> 药学 提交时间: 2024-08-15
摘要: [目的] 探究中国上市药品专利信息登记平台上存在的问题,提出仿制药企需要采取的策略。[方法] 通过数据挖掘,对中国上市药品专利信息登记平台上的2类专利声明数据进行整体分析与个案比较。[结果] 推举10款可供选择的化学仿制药品种。[局限] 中国的药品专利链接数据与海外国家的比较研究。[结论] 中国上市药品专利信息登记平台无依职权审查的纠错机制是中国药品专利链接制度的一重大缺陷。
分类: 农、林、牧、渔 >> 土壤学 提交时间: 2024-08-14 合作期刊: 《干旱区科学》
摘要: Wind erosion is a geomorphic process in arid and semi-arid areas and has substantial implications for regional climate and desertification. In the Columbia Plateau of northwestern United States, the emissions from fine particles of loessial soils often contribute to the exceedance of inhalable particulate matter (PM) with an aerodynamic diameter of 10 μm or less (PM10) according to the air quality standards. However, little is known about the threshold friction velocity (TFV) for particles of different sizes that comprise these soils. In this study, soil samples of two representative soil types (Warden sandy loam and Ritzville silt loam) collected from the Columbia Plateau were sieved to seven particle size fractions, and an experiment was then conducted to determine the relationship between TFV and particle size fraction. The results revealed that soil particle size significantly affected the initiation of soil movement and TFV; TFV ranged 0.304–0.844 and 0.249–0.739 m/s for different particle size fractions of Ritzville silt loam and Warden sandy loam, respectively. PM10 and total suspended particulates (TSP) emissions from a bed of 63–90 μm soil particles were markedly higher for Warden sandy loam than for Ritzville silt loam. Together with the lower TFV of Warden sandy loam, dust emissions from fine particles (<100 μm in diameter) of Warden sandy loam thus may be a main contributor to dust in the region's atmosphere, since the PM10 emissions from the soil erosion surfaces and its ensuing suspension within the atmosphere constitute an essential process of soil erosion in the Columbia Plateau. Developing and implementing strategic land management practices on sandy loam soils is therefore necessary to control dust emissions in the Columbia Plateau.
分类: 生物学 >> 生态学 提交时间: 2024-08-14 合作期刊: 《干旱区科学》
摘要: Soil erosion caused by unsustainable grazing is a major driver of grassland ecosystem degradation in many semi-arid hilly areas in China. Thus, grazing exclusion is considered as an effective method for solving this issue in such areas. However, some ecological and economic problems, such as slow grassland rejuvenation and limited economic conditions, have become obstacles for the sustainable utilization of grassland ecosystem. Accordingly, we hypothesized that the conflict between grassland use and soil conservation may be balanced by a reasonable grazing intensity. In this study, a two-year grazing fence experiment with five grazing intensity gradients was conducted in a typical grassland of the Loess Plateau in China to evaluate the responses of vegetation characteristics and soil and water losses to grazing intensity. The five grazing intensity gradients were 2.2, 3.0, 4.2, 6.7, and 16.7 goats/hm2, which were represented by G1–G5, respectively, and no grazing was used as control. The results showed that a reasonable grazing intensity was conducive to the sustainable utilization of grassland resources. Vegetation biomass under G1–G4 grazing intensity significantly increased by 51.9%, 42.1%, 36.9%, and 36.7%, respectively, compared with control. In addition, vegetation coverage increased by 19.6% under G1 grazing intensity. Species diversity showed a single peak trend with increasing grazing intensity. The Shannon-Wiener diversity index under G1–G4 grazing intensities significantly increased by 22.8%, 22.5%, 13.3%, and 8.3%, respectively, compared with control. Furthermore, grazing increased the risk of soil erosion. Compared with control, runoff yields under G1–G5 grazing intensities increased by 1.4, 2.6, 2.8, 4.3, and 3.9 times, respectively, and sediment yields under G1–G5 grazing intensities were 3.0, 13.0, 20.8, 34.3, and 37.7 times greater, respectively, than those under control. This result was mainly attributed to a visible decrease in litter biomass after grazing, which decreased by 50.5%, 72.6%, 79.0%, 80.0%, and 76.9%, respectively, under G1–G5 grazing intensities. By weighing the grassland productivity and soil conservation function, we found that both two aims were achieved at a low grazing intensity of less than 3.5 goats/hm2. Therefore, it is recommended that grassland should be moderately utilized with grazing intensity below 3.5 goats/hm2 in semi-arid hilly areas to achieve the dual goals of ecological and economic benefits. The results provide a scientific basis for grassland utilization and health management in semi-arid hilly areas from the perspective of determining reasonable grazing intensity to maintain both grassland production and soil conservation functions.
分类: 生物学 >> 生态学 提交时间: 2024-08-14 合作期刊: 《干旱区科学》
摘要: Atmospheric deposition of nitrogen (N) plays a significant role in shaping the structure and functioning of various terrestrial ecosystems worldwide. However, the magnitude of N deposition on grassland ecosystems in Central Asia still remains highly uncertain. In this study, a multi-data approach was adopted to analyze the distribution and amplitude of N deposition effects in Central Asia from 1979 to 2014 using a process-based denitrification decomposition (DNDC) model. Results showed that total vegetation carbon (C) in Central Asia was 0.35 (±0.09) Pg C/a and the averaged water stress index (WSI) was 0.20 (±0.02) for the whole area. Increasing N deposition led to an increase in the vegetation C of 65.56 (±83.03) Tg C and slightly decreased water stress in Central Asia. Findings of this study will expand both our understanding and predictive capacity of C characteristics under future increases in N deposition, and also serve as a valuable reference for decision-making regarding water resources management and climate change mitigation in arid and semi-arid areas globally.
分类: 地球科学 >> 大气科学 提交时间: 2024-08-14 合作期刊: 《干旱区科学》
摘要: The characteristics of drought in Xinjiang Uygur Autonomous Region (Xinjiang), China have changed due to changes in the spatiotemporal patterns of temperature and precipitation, however, the effects of temperature and precipitation—the two most important factors influencing drought—have not yet been thoroughly explored in this region. In this study, we first calculated the standard precipitation evapotranspiration index (SPEI) in Xinjiang from 1980 to 2020 based on the monthly precipitation and monthly average temperature. Then the spatiotemporal characteristics of temperature, precipitation, and drought in Xinjiang from 1980 to 2020 were analyzed using the Theil–Sen median trend analysis method and Mann–Kendall test. A series of SPEI-based scenario-setting experiments by combining the observed and detrended climatic factors were utilized to quantify the effects of individual climatic factor (i.e., temperature and precipitation). The results revealed that both temperature and precipitation had experienced increasing trends at most meteorological stations in Xinjiang from 1980 to 2020, especially the spring temperature and winter precipitation. Due to the influence of temperature, trends of intensifying drought have been observed at spring, summer, autumn, and annual scales. In addition, the drought trends in southern Xinjiang were more notable than those in northern Xinjiang. From 1980 to 2020, temperature trends exacerbated drought trends, but precipitation trends alleviated drought trends in Xinjiang. Most meteorological stations in Xinjiang exhibited temperature-dominated drought trend except in winter; in winter, most stations exhibited precipitation-dominated wetting trend. The findings of this study highlight the importance of the impact of temperature on drought in Xinjiang and deepen the understanding of the factors influencing drought.
分类: 生物学 >> 生态学 提交时间: 2024-08-14 合作期刊: 《干旱区科学》
摘要: The Three-River Source Region (TRSR) in China holds a vital position and exhibits an irreplaceable strategic importance in ecological preservation at the national level. On the basis of an in-depth study of the vegetation evolution in the TRSR from 2000 to 2022, we conducted a detailed analysis of the feedback mechanism of vegetation growth to climate change and human activity for different vegetation types. During the growing season, the spatiotemporal variations of normalized difference vegetation index (NDVI) for different vegetation types in the TRSR were analyzed using the Moderate Resolution Imaging Spectroradiometer (MODIS)-NDVI data and meteorological data from 2000 to 2022. In addition, the response characteristics of vegetation to temperature, precipitation, and human activity were assessed using trend analysis, partial correlation analysis, and residual analysis. Results indicated that, after in-depth research, from 2000 to 2022, the TRSR's average NDVI during the growing season was 0.3482. The preliminary ranking of the average NDVI for different vegetation types was as follows: shrubland (0.5762)>forest (0.5443)>meadow (0.4219)>highland vegetation (0.2223)>steppe (0.2159). The NDVI during the growing season exhibited a fluctuating growth trend, with an average growth rate of 0.0018/10a (P<0.01). Notably, forests displayed a significant development trend throughout the growing season, possessing the fastest rate of change in NDVI (0.0028/10a). Moreover, the upward trends in NDVI for forests and steppes exhibited extensive spatial distributions, with significant increases accounting for 95.23% and 93.80%, respectively. The sensitivity to precipitation was significantly enhanced in other vegetation types other than highland vegetation. By contrast, steppes, meadows, and highland vegetation demonstrated relatively high vulnerability to temperature fluctuations. A further detailed analysis revealed that climate change had a significant positive impact on the TRSR from 2000 to 2022, particularly in its northwestern areas, accounting for 85.05% of the total area. Meanwhile, human activity played a notable positive role in the southwestern and southeastern areas of the TRSR, covering 62.65% of the total area. Therefore, climate change had a significantly higher impact on NDVI during the growing season in the TRSR than human activity.
分类: 生物学 >> 生态学 提交时间: 2024-08-14 合作期刊: 《干旱区科学》
摘要: The Mongolian Plateau in East Asia is one of the largest contingent arid and semi-arid areas of the world. Under the impacts of climate change and human activities, desertification is becoming increasingly severe on the Mongolian Plateau. Understanding the vegetation dynamics in this region can better characterize its ecological changes. In this study, based on Moderate Resolution Imaging Spectroradiometer (MODIS) images, we calculated the kernel normalized difference vegetation index (kNDVI) on the Mongolian Plateau from 2000 to 2023, and analyzed the changes in kNDVI using the Theil-Sen median trend analysis and Mann-Kendall significance test. We further investigated the impact of climate change on kNDVI change using partial correlation analysis and composite correlation analysis, and quantified the effects of climate change and human activities on kNDVI change by residual analysis. The results showed that kNDVI on the Mongolian Plateau was increasing overall, and the vegetation recovery area in the southern region was significantly larger than that in the northern region. About 50.99% of the plateau showed dominant climate-driven effects of temperature, precipitation, and wind speed on kNDVI change. Residual analysis showed that climate change and human activities together contributed to 94.79% of the areas with vegetation improvement. Appropriate human activities promoted the recovery of local vegetation, and climate change inhibited vegetation growth in the northern part of the Mongolian Plateau. This study provides scientific data for understanding the regional ecological environment status and future changes and developing effective ecological protection measures on the Mongolian Plateau.
分类: 生物学 >> 生态学 提交时间: 2024-08-14 合作期刊: 《干旱区科学》
摘要: Understanding the response of vegetation variation to climate change and human activities is critical for addressing future conflicts between humans and the environment, and maintaining ecosystem stability. Here, we aimed to identify the determining factors of vegetation variation and explore the sensitivity of vegetation to temperature (SVT) and the sensitivity of vegetation to precipitation (SVP) in the Shiyang River Basin (SYRB) of China during 2001–2022. The climate data from climatic research unit (CRU), vegetation index data from Moderate Resolution Imaging Spectroradiometer (MODIS), and land use data from Landsat images were used to analyze the spatial-temporal changes in vegetation indices, climate, and land use in the SYRB and its sub-basins (i.e., upstream, midstream, and downstream basins) during 2001–2022. Linear regression analysis and correlation analysis were used to explore the SVT and SVP, revealing the driving factors of vegetation variation. Significant increasing trends (P<0.05) were detected for the enhanced vegetation index (EVI) and normalized difference vegetation index (NDVI) in the SYRB during 2001–2022, with most regions (84%) experiencing significant variation in vegetation, and land use change was determined as the dominant factor of vegetation variation. Non-significant decreasing trends were detected in the SVT and SVP of the SYRB during 2001–2022. There were spatial differences in vegetation variation, SVT, and SVP. Although NDVI and EVI exhibited increasing trends in the upstream, midstream, and downstream basins, the change slope in the downstream basin was lower than those in the upstream and midstream basins, the SVT in the upstream basin was higher than those in the midstream and downstream basins, and the SVP in the downstream basin was lower than those in the upstream and midstream basins. Temperature and precipitation changes controlled vegetation variation in the upstream and midstream basins while human activities (land use change) dominated vegetation variation in the downstream basin. We concluded that there is a spatial heterogeneity in the response of vegetation variation to climate change and human activities across different sub-basins of the SYRB. These findings can enhance our understanding of the relationship among vegetation variation, climate change, and human activities, and provide a reference for addressing future conflicts between humans and the environment in the arid inland river basins.
分类: 地球科学 >> 水文学 提交时间: 2024-08-14 合作期刊: 《干旱区科学》
摘要: Since the 1950s, numerous soil and water conservation measures have been implemented to control severe soil erosion in the Liuhe River Basin (LRB), China. While these measures have protected the upstream soil and water ecological environment, they have led to a sharp reduction in the downstream flow and the deterioration of the river ecological environment. Therefore, it is important to evaluate the impact of soil and water conservation measures on hydrological processes to assess long-term runoff changes. Using the Soil and Water Assessment Tool (SWAT) models and sensitivity analyses based on the Budyko hypothesis, this study quantitatively evaluated the effects of climate change, direct water withdrawal, and soil and water conservation measures on runoff in the LRB during different periods, including different responses to runoff discharge, hydrological regime, and flood processes. The runoff series were divided into a baseline period (1956–1969) and two altered periods, i.e., period 1 (1970–1999) and period 2 (2000–2020). Human activities were the main cause of the decrease in runoff during the altered periods, contributing 86.03% (–29.61 mm), while the contribution of climate change was only 13.70% (–4.70 mm). The impact of climate change manifests as a decrease in flood volume caused by a reduction in precipitation during the flood season. Analysis of two flood cases indicated a 66.00%–84.00% reduction in basin runoff capacity due to soil and water conservation measures in the upstream area. Soil and water conservation measures reduced the peak flow and total flood volume in the upstream runoff area by 77.98% and 55.16%, respectively, even with nearly double the precipitation. The runoff coefficient in the reservoir area without soil and water conservation measures was 4.0 times that in the conservation area. These results contribute to the re-evaluation of soil and water conservation hydrological effects and provide important guidance for water resource planning and water conservation policy formulation in the LRB.
分类: 地球科学 >> 地球科学其他学科 提交时间: 2024-08-13
摘要: The traditional uniformity coefficient Cu cannot reflect the uniformity of gap-graded granular mixtures. This paper proposes a new index CmuCum to quantify the uniformity of granular mixtures based on the study on their small-strain stiffness G0. The samples of granular mixtures with different fines content (FC) and particle size ratio (PSR) are prepared. The G0 values are determined by quasistatic drained triaxial tests on these samples. The CmuCum values are calculated from the obtained G0 values and can be expressed as a function of FC and PSR. The rationality of the proposed CmuCum is verified. The CmuCum can be used to predict the G0 of granular mixtures when the mechanical coordination number (CNm), shear modulus of particles (Gp), confining stress (σ0) and CmuCum are given.
分类: 力学 >> 生物力学 提交时间: 2024-08-13 合作期刊: 《应用力学学报》
摘要: 目的 对不同等级男子撑竿跳高运动员质心速度、质心高度、地面反作用力和下肢关节力矩等生物力学指标的具体表现进行探讨,试图了解不同等级运动员的整体特征,并发现高水平运动员助跑及起跳过渡衔接的特点。方法 使用大范围的三维动作捕捉系统以及3块测力台对优秀男子撑竿跳高运动员的运动学(200 Hz)和地面反作用力(2 000 Hz)数据进行采集,分析比较了5名一级运动员、4名运动健将和3名国际级运动健将的生物力学指标。对国际级运动健将组、运动健将组和一级运动员组的同一生物力学指标两两之间采用非参数独立样本曼-惠特尼U单侧检验,对所有运动员倒2步、倒1步和起跳相应的生物力学指标两两之间采用非参数配对样本Wilcoxon符号秩单侧检验。结果 不同等级撑竿跳高运动员助跑后两步和起跳的质心速度、质心高度、地面反作用力和下肢关节力矩等生物力学指标有显著性差异; 倒2步、倒1步、起跳相应的生物力学指标之间有显著性差异。结论 基于本研究的数据,男子撑竿跳高运动员表现出随等级而变化的生物力学特点,国际级健将运动员的质心速度、地面反作用力等指标体现了其较高的运动能力。倒2步、倒1步和起跳的质心速度、质心高度和地面反作用力等相应生物力学指标的显著差异反映了撑竿跳高技术动作的衔接特征,体现了撑竿跳高助跑向起跳过渡的运动学和动力学特点。
分类: 力学 >> 生物力学 提交时间: 2024-08-13 合作期刊: 《应用力学学报》
摘要: 通过力学建模方法对病人皮肤组织疾病进行诊断、评估和治疗,需要准确识别皮肤组织的力学性能。为此,提出了一种运用自适应模拟退火优化算法结合代理模型技术的皮肤组织本构参数识别方法。首先,采用有限元方法模拟皮肤单轴拉伸试验,获取不同参数组合下,皮肤组织的数值计算力学响应数据。为提高参数识别的计算效率,分别构建了响应面模型、克里金模型、椭球基神经网络3种代理模型来代替重复的仿真计算过程,并采用决定系数R2对3种代理模型的拟合精度进行校验。最后,利用自适应模拟退火优化算法,以试验曲线与数值计算曲线均方根误差最小为优化目标,通过反演识别出了与普通家猪腹肋部皮肤组织单轴拉伸试验结果最匹配的本构参数:C10=0.140 1 MPa、k1=24.51 MPa、k2=0.496 1、κ=0.317 1、φ=13.86°。结果表明,椭球基神经网络模型更适合拟合皮肤本构模型参数与应力应变响应间的非线性关系。对比识别出的数值计算曲线与试验曲线,表明自适应模拟退火算法结合代理模型技术是识别皮肤组织各向异性超弹性本构参数的快速、可靠方法。