分段变速加载对含瓦斯突出煤力学特性影响试验研究

为探究采动应力变化对含瓦斯突出煤力学特性的影响,利用RLW-500G煤岩三轴蠕变-渗流试验系统,对新景矿含瓦斯突出煤进行了不同围压和瓦斯压力下的常规三轴和分段变速加载力学试验。结果表明:煤样在2种应力路径下的全应力应变曲线均可分为压密、线弹性、塑性变形、应力跌落和残余应力5个阶段;随着围压的升高或者瓦斯压力的降低,煤体在2种应力路径下的强度和弹性模量均增大;相较于常规三轴,煤体在分段变速加载路径下的强度普遍增大,峰值轴向应变、峰值环向应变绝对值和峰值体积应变绝对值也普遍增大,失稳破坏瞬间应力跌落和能量释放更加剧烈。Mohr-Coulomb强度准则仍然适用于分段变速加载条件下的含瓦斯突出煤,该研究对于认识煤与瓦斯突出的发生机制具有一定的指导意义。     

Novel mesoporous microspheres of Al and Ni doped LMO spinels and their performance as cathodes in secondary lithium ion batteries

A facile, scalable, and solution-based technique is used to fabricate Al and Ni-doped (LiAl_0.1Mn_1.9O₄ and LiAl_0.1Ni_0.1Mn_1.8O₄) microspheres of lithium manganese oxide (LMO) spinels for use as reversible cathode materials for lithium ion batteries (LIBs). The spheres of the two samples exhibit different porosities. Cells with these LMO-based cathodes are then cycled between 4.5 V and 2 V to study their stabilities while simultaneously being subjected to the undesirable Jahn-Teller distortion that occurs around the ~3 V regime. The LiAl_0.1Mn_1.9O₄ (LAMO) and the LiAl_0.1Ni_0.1Mn_1.8O₄ (LANMO) cells exhibit comparable open circuit voltages (OCV) of 2.94 V and 2.97 V, respectively. During cell cycling, the LAMO cell exhibits a maximum specific capacity of 122.51 mAh g^?1 with a capacity fade of 65.35% after 75 cycles. The LiAl_0.1Ni_0.1Mn_1.8O₄ (LAMO) sample fares better and exhibits a maximum of 140.49 mAh g^?1 and a capacity drop of 52.59%. Detailed structural studies indicate that Ni doping and the greater degree of porosity of the LANMO sample to be a stabilizing factor. This is further confirmed by cyclic voltammetry (CV) and AC impedance spectra analysis.     

An evaluation of lead concentrations in imported hot sauces

In the last decade, the U.S. Food and Drug Administration (FDA) has issued several warnings and recalls for food products that exceed FDA standards for lead. Products containing chili peppers and salt were often suspected as sources of lead contamination, and included items such as candy that are routinely investigated. However, products such as hot sauces that contain similar ingredients have not been the focus of evaluations. This study quantified lead concentrations in imported hot sauces, evaluated product compliance to existing United States standards, and calculated potential dietary lead exposure for children using the Integrated Exposure Uptake Biokinetic Model. Finally, recommendations for reducing the risk of lead exposure from hot sauces are provided. Twenty-five (25) bottles of imported hot sauces manufactured in Mexico and South America were purchased in Clark County, Nevada. All hot sauces were analyzed for lead concentrations, pH, and leaded packaging. Hot sauces were analyzed by inductively coupled plasma mass spectrometry and packaging was analyzed using x-ray fluorescence technology. Four brands of hot sauces (16%) exceeded 0.1 ppm lead, the current FDA action level for lead in candy. Hot sauces with lead concentrations >0.1 ppm lead contained salt and were manufactured in Mexico. Subsequent analysis of additional lots of hot sauces exceeding 0.1 ppm lead revealed inconsistent lead concentrations between and within manufacturer lots. The lead concentrations of the plastic hot sauce lids ranged from below the limit of detection to 2,028 ppm lead. There was no association between lead concentrations in hot sauces and pepper type. These results indicate the need for more rigorous screening protocols for products imported from Mexico, the establishment of an applicable standard for hot sauce, and resources to allow for the enforcement of existing food safety policies. The data reported herein represent the first known investigation of lead concentrations in hot sauces.     

降雨主导型库岸滑坡变形时空分布特征

根据某大型水库近坝库岸滑坡8年的监测资料,对该滑坡变形的时空分布特征进行了分析。该滑坡变形的空间分布特征主要表现为3个方面的差异,即区域差异、高程差异和深度差异。而滑坡变形的时间分布特征主要体现在库水作用和降雨两个方面:在重点监测的Ⅱ区,库水作用只影响到其前端部分,对中、后部影响很小;该区的整体变形与降雨关系密切,响应明显。这些特征表明该滑坡为降雨主导型库岸滑坡,并有向稳定方向发展的趋势;但Ⅱ区特有的"后坐式"变形特征又存在一定的安全隐患,因此,该滑坡的监测还应长期进行。     

西南山区某气井井场地基稳定性模拟分析

中国西南山区蕴藏着丰富的天然气资源,但随着开发规模的日益扩大,天然气井逐步转向山区这类地质环境恶劣的地区。本文以西南山区某气井为原型,在详细阐明井场区地质环境背景特征的基础上,首先对井场出现的典型地质问题——地下采空区进行定性判断和分析;之后选用F lac-2D有限差分软件,对井场加载前/后地下采空区可能造成的井场地基应力和变形特征,采用双洞和采空区这2种计算模型,进行数值模拟分析。模拟结果表明,井场加载前/后地基最大位移量为2 mm,地基局部地段出现拉应力区,但总体上地基稳定。研究结论将为后期建设中井场建筑物的优化布局及基础的选型提供依据。     

不同瓦斯压力下煤体力学特性试验研究

为研究瓦斯对煤体力学特性的影响,设计不同瓦斯压力条件下煤体单轴压缩试验,研究煤样力学参数及变形特征随瓦斯压力的变化趋势,探讨瓦斯对煤体力学性质的影响机制,得出单轴压缩下煤样力学参数,并记录煤样的破坏形态.研究结果表明:随瓦斯压力增大,应力-应变曲线压实阶段增大,弹性阶段缩小,失稳破坏后曲线缓慢下降,抗压强度和弹性模量单...     

塑烧管除尘器在冶金精轧线的应用

冶金精轧线烟气烟尘含油含水，采用传统的布袋除尘等方式难以治理。塑烧管具有刚性结构、高过滤效率、压降稳定、疏水疏油性、防静电等特性，适合于治理含油含水的烟气。塑烧管除尘器在冶金精轧线的应用取得了良好的效果。     

对华北GPS监测区近期地壳应变连续分布的估计

直接利用华北ＧＰＳ监测网各个测点的位移观测值,借助高斯型位移协方差函数通过最小二乘配置建立连续分布的位移函数,并根据应变与位移的偏导关系,对华北ＧＰＳ监测区１９９２～１９９５年、１９９５～１９９６年最大剪应变及面膨胀连续分布进行估算,得到其应变场动态图像。     

提高节理面c和φ对岩坡开挖变形的影响

为了反映岩质边坡在节理面注浆后的变形效应,首先,通过室内试验,分析注浆前后岩体变形和破坏的全过程,以探讨其抗剪性能(粘结力c和内摩擦角φ)的变化;然后,基于理想弹塑性本构模型的Mohr-Cou-lomb准则,运用拉格朗日元数值方法(FLAC3D),对岩坡注浆前后变形效应(水平位移、垂直位移、剪应变增量)进行模拟。结果表明:注浆加固后,岩体的位移场变得均匀和连续,节理面处的较大位移受到抑制,边坡的整体性得到提高,有利于边坡的稳定性。     

碗窑碾压混凝土坝变形成因分析及监控指标的拟定

鉴于碗窑碾压混凝土重力坝个别变形测点测值异常现象,依据大坝变形观测资料,通过变形规律时空分析和统计模型的建立,以及影响因子的分解,合理地解释了其变形成因,从而得出碗窑水库大坝变形性态总体正常的结论。为确保大坝安全运行,通过建立有限元力学模型和混合模型,拟定了典型坝段坝顶水平位移的一级监控指标,进而更有效地监控大坝的安全性态。另外,就个别测点坝段时效有呈逐年缓慢上升的趋势,建议管理单位加强观测,并及时分析,确保工程安全运行。