几种改性磷肥的X射线衍射特征初报

运用X射线衍射技术对改性磷肥的结构进行研究,发现其晶体结构发生了较大的变化;这种晶体结构的变化减少了改性磷肥中有效磷在土壤中的固定,从而大大提高了其生物有效性,是生物量增加的主要原因。     

一种基于Landsat 8 OLI影像的水体信息提取方法研究

提出一种基于Landsat 8 OLI影像提取水体信息的斜率比值法（SR）,比对不同方法、不同类型水体和不同季节影像的数据,结果表明：SR法相比归一化差异水体指数法（NDWI）和改进的归一化差异水体指数法（MNDWI）,水体信息提取精度更高,且对阈值精确度的要求低,阈值一般设定为2.0;SR法适用于清澈水体、浑浊水体、浅水河滩等水体,对河流干流和较大支流的提取精度达到99%,细小支流、沟渠的提取精度为66%,面积较小的水体提取精度为65%;在冬季太阳高度角较低时,SR也能较好地去除阴影。     

平顶山矿区塌陷地区位分析与分区利用

矿区塌陷地是一种重要的土地资源和资产,对其利用要在空间上进行科学的规划和合理的布局。土地分区利用原理使我们对矿区塌陷地的利用由盲目的农业复垦而转到自觉的进行区位选择,使平顶山矿区塌陷地的利用符合其区位特征,从而实现塌陷地区位效益。     

低压配电线路剩余电流断路器动作判据的研究

为了改善剩余电流断路器频繁误动作的问题,提出以偶次谐波变化率最小值阈值、工频变化量阈值、剩余电流动作整定值相结合的三重判据.首先,搭建活体触电试验平台,获取活体不同部位的多组触电试验数据,利用S变换提取触电波形谐波特征,并计算出触电时刻偶次谐波变比率最小值阈值和工频变化量阈值.其次,搭建人体触电仿真模型,发现存在相似的...     

专业认证背景下的安全工程专业特色教育研究与实践

回顾专业认证在国内外的发展情况,简单介绍《安全工程专业本科教育认证标准》的内容和安全工程专业认证近年来在国内的发展情况。根据南华大学的实际情况,提出在专业认证的背景下,针对行业特点,实行分方向设置课程和从事教学活动。南华大学安全工程专业主要依托"核"行业背景,下设核安全、建筑安全和化工安全3个方向;3个专业方向分别设置了不同的基础课、专业基础课、专业课和选修课;课程设置符合《安全工程专业本科教育认证标准》的要求,并严格按照教学计划开展教学。实践证明,该项教学改革取得明显成效,该校安全工程专业近两年的就业率和考研率都居于全校前列,并且就业单位具有明显的行业特点。     

医护人员血源性病原体职业危害研究进展

本研究的目的是了解医护人员血源性病原体职业接触流行特征、职业危害及其研究进展。结果表明,发生针刺及其他锐器损伤的最主要的职业群体是护理人员,最容易导致医护人员损伤的锐器为注射器针头、玻璃安瓿、缝合针和手术刀片等,导致医护人员锐器伤的最常见的医疗操作是注射、缝合和采血。发生血源性病原体职业接触后,医护人员可能感染HBV、HCV及HIV等多种血源性病原体。国内既往研究大多关注伤害发生率及相关危险因素,未对血源性病原体职业接触后感染HBV、HCV及HIV的风险开展研究,尚需通过建立队列,开展前瞻性调查研究。     

天山公路溜砂坡动力学特性及分形特征试验研究

溜砂坡动力学特性研究是寻求有效防治措施的关键。本文通过天山公路溜砂坡的动力学特性物理模拟试验,初步探索了其崩滑的动力学机制,发现溜砂坡堆积呈现分形结构,表明其堆积过程是一个典型的自组织临界过程,整个坡体是一个广延耗散动力学系统。试验中发现了一种新的崩滑动力学机制——滑塌式崩滑,其失稳过程中存在一个潜在的滑动面,坡体呈现整体失稳的特征,颗粒呈现类似冲洪积物互层现象的堆积特征。     

丙烷扩散火焰燃烧光谱特性研究

为实现烃类火灾事故的光谱辨识,对丙烷火焰燃烧初期过程中的光谱特性进行实验研究,利用拉曼光谱仪等设备采集、提取丙烷扩散火焰光谱数据。分析燃烧初期OH~*,C₂~*,CH~*,H₂O分子谱带范围及特征峰值分布特性,揭示谱带光谱特征强弱的主要原因,阐述沿火焰轴向与径向C₂~*,CH~*以及H₂O分子光谱峰值强度的分布特性。研究结果表明：丙烷火焰特征光谱主要分布在可见光与近红外波段,250～380 nm的近紫外波段光谱强度较弱。C₂~*的509.4,512.8,810.5 nm特征谱带,CH~*的431.4 nm谱带以及H₂O分子的586.2,652.2 nm处振动-转动谱带可作为丙烷火焰燃烧的关键特征光谱,为烃类火灾的早期识别与防控提供光谱实验依据。     

The injury epidemiology of adult riders in vehicle-two-wheeler crashes in China,Ningbo, 2011–2015

Introduction: We used road crashes between vehicles and two-wheelers from Yinzhou District Ningbo in 2011–2015 from the China In-depth Accident Study (CIDAS) as sample cases. The risk factors of different injury severity grades were analyzed. Method: The classification tree model was used to screen the possible interaction items, and the corresponding regression model was constructed according to the results of the tree model to explore the influencing factors of cyclist injury. Results: The road types, weather types, gender, age of the riders, and vehicle speed were significantly correlated with the dependent variables. The interaction effect of gender*road type, weather*age, weather*speed and speed*age were obtained through a tree model. Conclusions: The risk of male casualties at the crossroads was 3.31 times higher than that of female casualties at the straight roads. On sunny days, the risk of crash casualties in Ningbo was low, and the fatality risk when the speed reached 38 km/h was 10%. Under the interaction effect of weather and age, the fatality risk in cloudy/foggy and rainy days was almost coincident, and the serious risk in cloudy/foggy conditions was the highest. Practical applications: Through factor analysis, it is confirmed that there is interaction effect among the factors, and it can provide reference for relevant departments to formulate more targeted and effective governance strategies.     

Metallurgical analysis of the ‘cause’ arc beads pattern characteristics under different short-circuit currents

Electric arc beads commonly cause large fire and explosion accidents, especially during the powder process industries. During such fires, the original equipment is often severely burned, rendering electrical fire investigation impossible. Therefore, identifying the beads caused by electrical faults through metallurgical investigation is crucial. This study focused on the ‘cause’ of arc beads and determined their pattern characteristics through metallurgical analysis of copper wires with short-circuit currents of 100, 160, 200, and 240 A. According to microstructure characteristics and metallographic knowledge, bead pattern characteristics were divided into six types: hypereutectic (A), dendritic eutectic (B), chilled layer (C), cellular crystal (D), dendritic (E), and coarse columnar crystal (F). Oxide levels of each category were A (4.5%–7.6%) > C (2.0%–3.8%) > B (1.1%–2.4%) > D (1.0%–2.1%) > E (0.6%–1.9%) > F (0.1%–0.7%). When the short-circuit currents were the same, there were a greater number of small particle beads than large ones. As the current increased, the number of distributed beads with a particle size d < 1 mm decreased, with 1 mm ≤ d < 2 mm increased, and with d ≥ 2 mm were stable. Bead size and distribution had a negative linear correlation at 200 A. When the current increased, the proportion of beads with A and C structures gradually decreased, and those with D structures increased to more than 50%. Oxygen content and arc temperature determined the oxide form. These results are vital for electrical fire investigations and provide theoretical support for fire material evidence extraction and cause identification.