应用综合指标评价底分层突出危险性

具有突出特性的厚煤层分层开采时,对其底分层是否消除突出危险性,采用多个指标并结合芦岭矿Ⅱ824的下分层Ⅱ824-2工作面的情况,进行了应用性的突出危险评价。     

Simplified Calculation Methods for Static Behaviors of Triple-Tower Suspension Bridges and Parametric Study

International Journal of Steel Structures - In this paper, simplified formulas to determine the static behaviors of triple-tower suspension bridges were derived, including the formulas for the...     

Role of molecular structure on bioelectrochemical reduction of mononitrophenols from wastewater

The effect of nitro-substituent on mononitrophenol (o-nitrophenol (ONP), m-nitrophenol (MNP) and p-nitrophenol (PNP)) reduction in a bioelectrochemical system (BES) was investigated in this study. The results show that the removal of all three nitrophenols was significantly enhanced with more negative cathode potential and shortened hydraulic retention time in the BESs. Moreover, the reduction of the three nitrophenols followed in the order of ONP > MNP > PNP in the BESs. Both quantum chemical calculation using density function theory and cyclic voltammetry analysis confirmed the reductive sequence of the three nitrophenols. In addition, the acute toxicity of nitrophenol effluent significantly decreased while its biodegradability was enhanced after treatment in the BES. Therefore, the BES technology offers bright prospects for efficient treatment of nitrophenol-containing wastewater.     

气流扰动下单液滴撞击单根干燥扁网丝特性数值研究

丝网分离器在工业中有着广泛地应用。本文针对液滴撞击网丝的动态过程,采用CLSVOF方法对单个液滴撞击干燥网丝的问题进行数值模拟,经过合理的简化,建立了气流扰动下单液滴撞击干燥扁网丝面的二维数学模型,分析了液滴撞击角和撞击位置对液滴撞击行为特性的影响。数值计算的结果表明:液滴撞击到干燥网丝上分为铺展和飞溅2个过程,撞击角越小,上铺展半径越大,下铺展半径越小,分离的二次液滴体积越大;液滴撞击网丝的位置离网丝边缘越近,越容易产生二次液滴,二次液滴的总体积越多。     

南京越江盾构隧道纵向抗弯能力研究

针对南京越江盾构隧道建立了三维有限元实体模型,根据中性轴的位置通过施加节点荷载的方法来施加纵向弯矩.模型中将管片环视为一均质体,采用接触单元来模拟管片环之间的相互作用.纵向螺栓采用梁单元来模拟,并考虑预紧力作用.计算表明,接触面上的受压区仅位于环缝上端很小一部分区域,环缝张开区域较大,但较大裂隙的分布也局限于环缝下端一小块区域.在弹性状态下,螺栓的轴力、最大拉应力与纵向弯矩基本上成线性关系.该工作可为管片结构的设计提供参考.     

Plate-like carbon-supported Fe_3C nanoparticles with superior electrochemical performance

Iron-based anodes for lithium-ion batteries(LIBs) with higher theoretical capacity,natural abundance and cheapness have received considerable attention,but they still suffer from the fast capacity fading.To address this issue,we report a facile synthesis of plate-like carbonsupported Fe3 C nanoparticles through chemical blowing/carbonization under calcination.The ultrafine Fe3 C nanoparticles are prone to be oxidized when exposing in air;thus,Fe3 C/C with mild oxidization and the fully oxidized product of Fe_2 O_3/C are successfully prepared by controlling the oxidization condition.When applied as an anode material in LIB,the Fe3 C/C electrode demonstrates excellent cycle stability(826 mAh·g~(-1) after 120 cycles under 500 mA·g~(-1)) and rate performance(410.6 mAh·g~(-1)under 2 A·g~(-1)),compared with the Fe_2 O_3/C counterpart.The enhanced electrochemical performance can be ascribed to the synergetic effect of the Fe3 C with mild oxidation and the unique hierarchical structure of plate-like carbon decorated with Fe_3 C catalyst.More importantly,this work may offer new approaches to synthesize other transition metal(e.g.,Co,Ni)-based anode material by replacing the precursor ingredient.     

某大型特种工程车液压系统故障本体构建

为实现某大型特种工程车液压系统故障知识的共享,提出利用本体进行故障建模。根据液压系统特点设计出本体,针对本体难以描述的复杂故障引进SWRL,建立SWRL规则,最后进行实例的推理,结果表明利用本体和SWRL可以实现故障表示和故障推理。     

电流辅助对铆钉压铆过程及连接性能的影响

钛合金铆钉在塑性成型过程中存在变形抗力大、变形不均匀等问题。在铆接过程中引入电流辅助铆接技术可有效提升钛合金铆钉的铆接质量,其原理为通过在铆接过程中施加电流,改善金属铆钉塑性,提高铆钉的可加工性。以TA2M航空用铆钉为研究对象,研究了6种电流密度水平下铆钉的温升过程与成型效果,并开展拉伸试验与疲劳试验研究铆接件的力学性能。研究发现,通电会在较短时间内产生显著的焦耳热效应,这对难变形的钛合金铆钉来说是一种有效的热软化手段;通电带来的铆钉软化效应极大降低了加工难度,改善了镦头的成型效果;当通以电流密度为26 A/mm²的电流时,压铆力降低了24.69%,且镦头直径增大了6.80%,高度降低了14.04%,更加接近标准所要求的尺寸;电流辅助铆接技术对钛合金板连接件静态拉伸强度的影响不显著,但可有效提升连接件的疲劳寿命。     

A vacuum ultraviolet laser with a submicrometer spot for spatially resolved photoemission spectroscopy

Vacuum ultraviolet(VUV)lasers have demonstrated great potential as the light source for various spectroscopies,which,if they can be focused into a small beam spot,will not only allow investigation of mesoscopic materials and structures but also find application in the manufacture of nano-objects with excellent precision.In this work,we report the construction of a 177 nm VUV laser that can achieve a record-small(〜0.76 μm)focal spot at a long focal length(~45 mm)by using a flat lens without spherical aberration.The size of the beam spot of this VUV laser was tested using a metal grating and exfoliated graphene flakes,and we demonstrated its application in a fluorescence spectroscopy study on pure and Tm3+-doped NaYF4 microcrystals,revealing a new emission band that cannot be observed in the traditional up-conversion process.In addition,this laser system would be an ideal light source for spatially and angleresolved photoemission spectroscopy.