碳同位素在油气地质研究中的应用和进展

稳定同位素地球化学是发展较快的学科之一，七十年代起被广泛应用于油气地球化学研究中。本文综述了碳稳定同位素在油气地质研究中的应用和进展，这些应用主要包括确定源油的形成环境与形成时代；进行油／油、油／源对比；判别天然气的成因类型并进行对比；判断天然气的成熟度。     

拉伸型渭河盆地地震孕育发生的构造模型

依据拉伸型渭河盆地块体周边断裂活动特征和块体运动特征,建立了盆地地震孕育发生的构造模型,旨在探索地震孕育发生的机制,为研究类似盆地地震孕育、发生及其分布规律和地震监测预报、震灾防御等各项防震减灾工作部署提供科学依据。     

The safety implications of vehicle seat adjustments

INTRODUCTION: The goal of this study was to gather information on the preferred front seat position of vehicle occupants and to determine the impact of variation in seat position on safety during crashes. METHOD: The study evaluated the relationship between seat position and occupant size using the chi-square test and compared the risk of severe injury for small females and large males with regard to forward and rearward seat position using logistic regression. RESULTS: While smaller drivers sat closer to the steering wheel than larger drivers, front passengers of all sizes used similar seat positions. Additionally, the risk of injury was higher for small, unbelted females in rearward seat positions and large males (belted and unbelted) in forward seat positions. CONCLUSIONS: Occupants who adjust their seats to positions that are not consistent with required federal tests are at a greater risk for severe injury in a crash.     

不同土地利用类型的地表特征参量的遥感反演研究——以猫跳河流域为例

利用2007年5月Lansat5 TM数据,运用单通道算法,基于全国遥感监测土地利用/覆盖分类体系,对贵州省猫跳河流域的地表特征参量进行了反演,得到不同土地利用类型下的典型地表特征参数值。在3种主要的土地利用类型中,林地的植被指数最高、地表温度最低,农田的植被指数最低而地表温度最高,草地介乎林地和农田之间。城镇建设用地主要表现为热岛效应,而水域则主要表现为地表温度（LST）和归一化植被指数（NDVI）的双低特征。进一步对二级土地利用类型的分析表明,由于结构、功能的不同,土地利用二级类在地表特征参量方面也表现出了有规律地变化。有助于深入认识不同土地利用类型的物理特征,可以丰富主要土地利用类型的影像分类的先验知识,有望将不同土地利用方式的生态环境效应研究推进一步     

家具企业喷涂过程呼吸防护技术应用研究

随着家具行业持续高速发展和从业人数的不断增加,家具企业职业危害的严峻性也日益突显,职业危害预防、控制也越来越受重视。喷涂作为家具表面处理的重要工艺,其作业过程产生的漆雾和挥发性有机化合物更是直接威胁到职工的健康安全。基于对家具企业喷漆作业场所的有毒、有害因素分析研究的基础上,从个体职业危害防护的角度,提出适用于家具企业喷漆过程的固定式长管呼吸装置防护技术,加强对家具企业职工喷漆作业的劳动保护,实现职业危害的预防控制。     

空心莲子草对水分变化的形态适应研究

在人工栽培空心莲子草并控制其立地水分条件,使之形成相应三种生境类型——旱生型、挺水型、漂浮型的条件下,初步研究了空心莲子草对水因子变化的形态适应机理。对节间长度、不定根数、不定根长度、叶形指数、抽枝率、节间最大周长等六个形态学指标进行的单因素方差分析和因子分析的结果表明：水分条件的变化对全部形态参数都有极显著影响;旱生型空心莲子草以地上部迅速占有空间的生长为主,其次是地下部生长;与旱生型空心莲子草相比,漂浮型的生长趋势中茎的增粗生长和根的数量生长上升到重要位置,然后才是茎与根的伸长生长;挺水型的第一位生长具有旱生型与漂浮型的双重特点,第二位生长在一定程度上具有与漂浮型相同的特征。按旱生型—挺水型—漂浮型逐级过渡,节间长度、不定根数极显著增加;第一公共因子中不定根数的重要性逐步升高,而且抽枝率始终是重要参数,但其均值在漂浮型中最小。所以,对旱生型与挺水型空心莲子草的治理应以抑制其抽枝为主要手段,对于漂浮型则应以抑制其生根为主。后续的相关研究应该以寻找其根和茎的发育机理为主,并以此为突破口采用适当的方法治理该种的蔓延。     

不同产酸发酵菌群产氢能力的对比与分析

重点对乙醇型发酵菌群和丙酸型发酵菌群的产气及产氢能力进行了对比研究,并对发酵菌群由丙酸型演替为乙醇型过程中的产氢速率变化进行了分析.在有机负荷相同的条件下,乙醇型发酵菌群表现出较高的产氢速率和比产氢速率,最大产氢速率为14.99L/d,最大比产氢速率为3586.45mmol/(kg·d).而丙酸型发酵菌群产氢速率和比产氢速率都较低,分别为3.62L/d,196.46mmol/(kg·d)生物制氢反应器在运行中维持乙醇型发酵更有利于获得较高的氢气产量,应尽量避免丙酸型发酵的发生.     

A study on chest injury mechanism and the effectiveness of a headform impact test for pedestrian chest protection from vehicle collisions

This study was aimed at investigating the injury mechanism of pedestrian chests in collisions with passenger vehicles of various frontal shapes and examining the influence of the local structural stiffness on the chest injury risk by using the headform impact test at the chest contact area of the vehicle. Three simulations of vehicle to pedestrian collisions were conducted using three validated pedestrian finite element (FE) models of three pedestrian heights of 177 (AM50th), 165 and 150 cm and three FE vehicles models representing a one-box vehicle, a minicar and a medium car. The validity of the vehicle models was evaluated by comparing the headform acceleration against the measured responses from headform impact tests. The chest impact kinematics and the injury mechanisms were analyzed in terms of the distribution of the von Mises stress of the ribcage and in terms of the chest deflections. The chest contact locations on the front panel and the bonnet top were identified in connection to the causation of rib fractures. The risk of rib fractures was predicted by using the von Mises stress distribution. The headform impact tests were carried out at the chest contact area on the front panel and bonnet to examine the safety performance with respect to pedestrian chest protection. In simulations of the one-box vehicle to pedestrian collisions, the chest was struck directly by the frontal structure at a high velocity and deformed substantially, since a shear force was generated by the stiff windshield frame. The acceleration of the headform was related to the rib deflections. The injury threshold of the ribcage deflection (42 mm) corresponded to the headform average acceleration of 68 G. In the minicar collision, the chest was struck with the bonnet top and cowl area at a low velocity, and the deformation was small due to the distributed contact force between the chest and the bonnet top. Besides, the ribcage deformation was too small for bridging a relation between the headform accelerations and rib deflections. In the medium car collision, the deformation mode of the chest was similar to that in the minicar collision. The chest collided with the bonnet top at a low velocity and deformed uniformly. The deflection of the ribs had an observable correlation with the headform accelerations measured in the headform impact tests. The frontal shape of a vehicle has a large influence on a pedestrian’s chest loadings, and the chest deformation depends on the size of the pedestrian and the stiffness of the vehicle. The one-box passenger vehicle causes a high chest injury risk. The headform impactor test can be utilized for the evaluation of the local stiffness of a vehicle’s frontal structure. The reduction of the headform acceleration is an effective measure for pedestrian chest protection for specific shapes of vehicles by efficacy in modifying the local structural stiffness.     

散煤运输用膜型抑尘剂的制备及性能研究

采用水溶液聚合法,以氧化淀粉、丙烯酸(AA)、二甲基二烯丙基氯化铵(DMDAAC)为原料,通过接枝共聚制备了一种软膜型抑尘剂(抑尘剂液体干燥后形成具有一定韧性的软膜)。与聚乙烯醇类壳型抑尘剂(干燥后形成很脆的壳层)相比,软膜型抑尘剂提高了煤粉固化层的抗破裂能力。由抗震荡性试验可知,使用膜型抑尘剂后,经过18 h的震荡,煤粉的损失率仅为1.91%,而使用壳型抑尘剂后煤粉的损失率为4.85%。还测定了2种抑尘剂的保湿性和耐破度。利用红外光谱对产物的结构进行了表征,采用SEM观察了该产物在煤粉表面形成的膜层形貌。试验结果表明,散煤运输中膜型抑尘剂在减少煤粉损失和控制扬尘污染方面性能优于壳型抑尘剂。     

Plant biomass allocation strategies of the dominant species in an alpine meadow of northwestern Sichuan,China北大核心CSCD

Plant biomass partitioning is an important driver of whole-plant net carbon gain, as biomass allocation could directly affect plant's future growth and reproduction. Alpine meadow in the northwestern Sichuan was impressed by the abundant community structure and species diversity. This study on biomass allocation pattern of different functional types and lifeforms might help understand plant life-history strategy of alpine meadow plants. We investigated 72 dominant herbaceous species for their compartments, biomass, and morphological traits during 2012-2014. These plants were sampled from natural grassland, disturbed grassland, and wintergreen grassland; they belonged to three functional types (grass, sedge, and forb) and two lifeforms (annual and perennial). The scaling relationships between functional traits of these plants were analyzed using Model type II regression method to estimate the parameters of the allometric equations. (1) Biomass allocation proportion of components significantly differed among grasses, sedges, and forbs owing to phylogeny: grasses had the highest stem biomass percentage, sedges had higher root biomass percentage, and forbs had higher leaf biomass percentage, but the scaling relationships were not significantly different, and isometric scaling was noted between biomass components for the three functional types. (2) Moreover, plant lifeforms affected the biomass allocation proportion of components, owing to the shorter or longer turnover rate and investment strategy between annual and perennial species. Annuals allocated more biomass to the stem and reproduction organs, but perennials invested more biomass to the leaves and roots. (3) In addition, plants from different grassland types differed in both biomass and morphology traits. Moreover, forbs from natural grassland and wintergreen grassland had higher leaf and reproductive biomass, but those from disturbed grasslands had higher stem biomass. Our results suggest that the functional type and lifeform decide the inherent scaling relationships between components of plants, but anthropogenic disturbance significantly impacted the quantity of component biomass. This study has important theoretical and practical significance to understand the response of alpine plants to climate change and anthropogenic disturbance as well as to help in the scientific management of alpine meadow. © 2018 Science Press. All rights reserved.