目的探讨不同物理特性实时噪声环境对视觉相关作业工效的影响。方法 40名在校大学生青年志愿者随机分为不同强度组[对照组(环境背景噪声不高于40 d BA)、65 d BA白噪声组、75 d BA白噪声组]、不同频率组[低频谱组(<500Hz)、中高频谱...目的探讨不同物理特性实时噪声环境对视觉相关作业工效的影响。方法 40名在校大学生青年志愿者随机分为不同强度组[对照组(环境背景噪声不高于40 d BA)、65 d BA白噪声组、75 d BA白噪声组]、不同频率组[低频谱组(<500Hz)、中高频谱组(500~3000 Hz),强度均为75 d BA]。使用NES-C4测试系统对各组人员的视觉相关神经行为功能进行测试。结果与对照组相比,65 d BA和75 d BA强度噪声可显著影响受试者在视觉保留、视觉反应时、曲线吻合、目标追踪、立体视觉项目的得分(P<0.05),且呈现噪声强度越高影响越大的趋势;设定75 d BA条件下,不同频率噪声对受试者视觉保留、视觉反应时间、曲线吻合、目标追踪、立体视觉各项指标的影响均未见显著差异(P>0.05)。结论作业环境中噪声强度是影响视觉相关作业工效的主要因素。展开更多
Re-vegetation plays a fundamental role for erosion control and plant recovery in lands affected by gully erosion. Bioengineered practices facilitate the gullies rehabilitation. Objectives of the research were: 1) Iden...Re-vegetation plays a fundamental role for erosion control and plant recovery in lands affected by gully erosion. Bioengineered practices facilitate the gullies rehabilitation. Objectives of the research were: 1) Identify taxonomically the pioneer vegetation on each gully section; 2) Characterize vegetation distribution preferences and 3) Assess structural/functional traits to recognize erosion control key species. Bioengineering was applied in a watershed belonging to Sierra Madre del Sur, at Oaxaca, Mexico, on eight gullies, with local support and minimal investment. "La Mixteca" is a poor ecological and socio-economic region, comparable to other regions of the world. The Initial Floristic Composition(IFC) inventory is the baseline of the successional process. The transect method was used to determine the colonization of species. Cover abundance of registered species was estimated using the semi-quantitative scale of Braun-Blanquet. This procedure was repeated in five different positions(floor, hillslopes and tops), in the cross section of the gully. Throughcorrespondence analysis and clustering, the distribution of species was analyzed. Adequate responses were obtained in soil retention(quantity) and plant cover(existence and diversity); as measurable indicators of the bioengeneering works efficiency. Occupation of soil by native species from the Tropical Deciduous Forest was favored using live barriers. We detected species guilds with spatial distribution preferences in the gullies cross section. Plant cover characterization includes: native colonizer species, herbaceous, shrubby and trees of the forest community bordering the gully area, with cover abundance and structural/functional traits, useful to protect degraded areas. This spatial occupation process of plants responds to a secondary succession in gullies, where the proposed IFC model is correctly represented through bioengineering. Natural establishment of plants was successful by traits of species such as extensive root system and sexual/vegetative reproduction.展开更多
From the measurement of liquid flow field on a large plate by a hot-film anemometer, three different regions on the large plate were presented, including a liquid circulation area near the inlet down-comer, a region w...From the measurement of liquid flow field on a large plate by a hot-film anemometer, three different regions on the large plate were presented, including a liquid circulation area near the inlet down-comer, a region with very slow moving or stagnant liquid on the side of the tray and an active flow region at the center of the plate. According to the contribution of the three regions, the tray efficiency for large plates was proposed. The prediction plate efficiency by the present model are compared with the experimental data in the literature and those calculated by other models. It is shown that the present model is more accurate for prediction of efficiency of large plates, and the calculation is simpler.展开更多
This paper argues that models developed in 20th century management literature can offer a valuable perspective on the organization of the ancient Roman wine trade. Similar to modem business, Roman entrepreneurs tried ...This paper argues that models developed in 20th century management literature can offer a valuable perspective on the organization of the ancient Roman wine trade. Similar to modem business, Roman entrepreneurs tried to enhance efficiency by implementing a wide range of techniques according to goals and available resources. The famous Ansoff matrix is used to analyse these techniques in function of the markets supplied by Roman merchants and the product diversification they applied. This approach explains how Roman entrepreneurs tried to cope with the limitations of a volatile pre-industrial business world： only the combination of a large family of semi-dependent agents and elite capital allowed successful large-scale engagement in the wine trade.展开更多
文摘目的探讨不同物理特性实时噪声环境对视觉相关作业工效的影响。方法 40名在校大学生青年志愿者随机分为不同强度组[对照组(环境背景噪声不高于40 d BA)、65 d BA白噪声组、75 d BA白噪声组]、不同频率组[低频谱组(<500Hz)、中高频谱组(500~3000 Hz),强度均为75 d BA]。使用NES-C4测试系统对各组人员的视觉相关神经行为功能进行测试。结果与对照组相比,65 d BA和75 d BA强度噪声可显著影响受试者在视觉保留、视觉反应时、曲线吻合、目标追踪、立体视觉项目的得分(P<0.05),且呈现噪声强度越高影响越大的趋势;设定75 d BA条件下,不同频率噪声对受试者视觉保留、视觉反应时间、曲线吻合、目标追踪、立体视觉各项指标的影响均未见显著差异(P>0.05)。结论作业环境中噪声强度是影响视觉相关作业工效的主要因素。
基金World Wildlife Fund (WWF) for providing financial support for the conduction of the research through Oaxaca Community Foundationthe National Council for Science and Technology supported the first author through grant for two years
文摘Re-vegetation plays a fundamental role for erosion control and plant recovery in lands affected by gully erosion. Bioengineered practices facilitate the gullies rehabilitation. Objectives of the research were: 1) Identify taxonomically the pioneer vegetation on each gully section; 2) Characterize vegetation distribution preferences and 3) Assess structural/functional traits to recognize erosion control key species. Bioengineering was applied in a watershed belonging to Sierra Madre del Sur, at Oaxaca, Mexico, on eight gullies, with local support and minimal investment. "La Mixteca" is a poor ecological and socio-economic region, comparable to other regions of the world. The Initial Floristic Composition(IFC) inventory is the baseline of the successional process. The transect method was used to determine the colonization of species. Cover abundance of registered species was estimated using the semi-quantitative scale of Braun-Blanquet. This procedure was repeated in five different positions(floor, hillslopes and tops), in the cross section of the gully. Throughcorrespondence analysis and clustering, the distribution of species was analyzed. Adequate responses were obtained in soil retention(quantity) and plant cover(existence and diversity); as measurable indicators of the bioengeneering works efficiency. Occupation of soil by native species from the Tropical Deciduous Forest was favored using live barriers. We detected species guilds with spatial distribution preferences in the gullies cross section. Plant cover characterization includes: native colonizer species, herbaceous, shrubby and trees of the forest community bordering the gully area, with cover abundance and structural/functional traits, useful to protect degraded areas. This spatial occupation process of plants responds to a secondary succession in gullies, where the proposed IFC model is correctly represented through bioengineering. Natural establishment of plants was successful by traits of species such as extensive root system and sexual/vegetative reproduction.
基金Supported by the National Natural Science Foundation of China(No. 20176037)
文摘From the measurement of liquid flow field on a large plate by a hot-film anemometer, three different regions on the large plate were presented, including a liquid circulation area near the inlet down-comer, a region with very slow moving or stagnant liquid on the side of the tray and an active flow region at the center of the plate. According to the contribution of the three regions, the tray efficiency for large plates was proposed. The prediction plate efficiency by the present model are compared with the experimental data in the literature and those calculated by other models. It is shown that the present model is more accurate for prediction of efficiency of large plates, and the calculation is simpler.
文摘This paper argues that models developed in 20th century management literature can offer a valuable perspective on the organization of the ancient Roman wine trade. Similar to modem business, Roman entrepreneurs tried to enhance efficiency by implementing a wide range of techniques according to goals and available resources. The famous Ansoff matrix is used to analyse these techniques in function of the markets supplied by Roman merchants and the product diversification they applied. This approach explains how Roman entrepreneurs tried to cope with the limitations of a volatile pre-industrial business world： only the combination of a large family of semi-dependent agents and elite capital allowed successful large-scale engagement in the wine trade.
