Inexpensive substrate sampler for macroinvertebrates

Assessment of aquatic macroinvertebrates is a critical component of many watershed monitoring programs and passive samplers are often used to collect long-term site data, especially in environments where active sampling is not possible. However, standard passive samplers can be expensive and lost in extreme conditions. We developed a sampler using plastic soda bottles (PSB) filled with river rock and compared its effectiveness with standard Hester-Dendy samplers in both lotic and lentic environments. Abundance, taxa richness, and macroinvertebrate composition showed no significant differences between sampler types in either habitat type. PSB samplers, which can be constructed for less than one dollar each, collected the same number of organisms and represented the same diversity as Hester-Dendy devices that cost around $38 each. In studies where funds are limited, PSB samplers appear to be suitable for passive monitoring.     

循环载荷下煤裂隙演化试验研究

为了研究循环载荷下的煤体裂隙演化特征，在不同应力水平和不同频率条件下分别进行煤样破坏力学及声发射试验。结果表明:应力-应变曲线呈疏-密-疏的变化特征，对应的振铃数柱状图呈U型；上限应力点的应变值、累积能量、撞击计数均随循环次数增加而上升，曲线呈倒S型；煤裂隙演化经历了原始裂隙闭合、新生裂隙稳定发育和裂纹贯穿破坏等3个不同阶段；循环载荷的应力水平和加载频率对煤体疲劳寿命的影响具有差异性，对煤体裂隙演化和破坏模式均有明显影响。     

基于多孔环形喷嘴的可燃爆粉尘分散特征的密度效应研究*

为了研究不同密度的可燃爆粉尘在内置多孔环形喷嘴的20 L爆炸特性测试装置中的分散特征，基于负载粒子流方法、耦合DPM动量平衡方程和时间平均 Navier Stokes控制方程组，实现3种不同密度的煤粉、铝粉和锆粉在20 L爆炸测试装置中粉尘分散全过程的数值模拟。研究结果表明:多孔环形喷嘴的分散较为均匀，但是约束管道末端存在局部粉尘残留区，致使爆炸仓内真实粉尘浓度远低于形式浓度；爆炸仓中心位置的最大湍动能随着粉尘密度的增加而减小，只有显著地变化粉尘密度才能展示区分度较高的浓度峰值和抵达浓度峰值的时间。     

加轴压卸围压下含瓦斯煤岩损伤变形的能量演化机制

采动影响下含瓦斯煤岩的损伤变形是一个极其复杂的非线性过程，单纯依靠传统经典弹塑性力学无法准确分析其破坏机理。针对此情况，通过试验研究了不同初始围压条件下含瓦斯煤岩的损伤变形特征，并分析了损伤变形与能量演化规律之间的内在联系。研究表明:初始围压越高，煤样破坏时强度越大，脆性破坏特征越明显，瓦斯流量急剧增加幅度越大，煤样破坏时积累的总能量和弹性应变能越多，且初始围压与弹性能之间满足对数函数关系。采用累积耗散能定义了煤岩损伤变量，并分析了不同阶段损伤与渗透率之间的演化关系。     

Validation of a booted finite element model of the WIAMan ATD lower limb in component and whole-body vertical loading impacts with an assessment of the boot influence model on response

Objective: A novel anthropomorphic test device (ATD) representative of the 50th percentile male soldier is being developed to predict injuries to a vehicle occupant during an underbody blast (UBB). The main objective of this study was to develop and validate a finite element (FE) model of the ATD lower limb outfitted with a military combat boot and to insert the validated lower limb into a model of the full ATD and simulate vertical loading experiments.

Methods: A Belleville desert combat boot model was assigned contacts and material properties based on previous experiments. The boot model was fit to a previously developed model of the barefoot ATD. Validation was performed through 6 matched pair component tests conducted on the Vertically Accelerated Loads Transfer System (VALTS). The load transfer capabilities of the FE model were assessed along with the force-mitigating properties of the boot. The booted lower limb subassembly was then incorporated into a whole-body model of the ATD. Two whole-body VALTS experiments were simulated to evaluate lower limb performance in the whole body.

Results: The lower limb model accurately predicted axial loads measured at heel, tibia, and knee load cells during matched pair component tests. Forces in booted simulations were compared to unbooted simulations and an amount of mitigation similar to that of experiments was observed. In a whole-body loading environment, the model kinematics match those recorded in experiments. The shape and magnitude of experimental force–time curves were accurately predicted by the model. Correlation between the experiments and simulations was backed up by high objective rating scores for all experiments.

Conclusion: The booted lower limb model is accurate in its ability to articulate and transfer loads similar to the physical dummy in simulated underbody loading experiments. The performance of the model leads to the recommendation to use it appropriately as an alternative to costly ATD experiments.     

井下采空区构筑物漏风实测装置研发及应用

为了实时动态监测采空区构筑物漏风情况，自主研发了一种井下采空区构筑物漏风实测装置。通过现场实测及应用，研究结果表明:风流从工作面上进风口漏入采空区，而采空区中风流一部分通过与工作面之间的漏风流进入工作面下进风口，在下隅角位置附近形成一个涡流区；另一部分风流穿过沿空留巷构筑物进入留巷内，由于采空区的压实程度不同，采空区侧留巷内漏风速度曲线近似呈“L”型下降；通过收集分析留巷内漏风气体，其结果可反映采空区中瓦斯浓度分布情况，为采空区瓦斯治理提供了一种新的监测技术手段，且能有效地降低采空区瓦斯事故发生率，保证矿井的安全生产。     

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。     

火车装油过程初期火灾扑救方法探讨

以敞口、小鹤管、人工装汽油为例,通过试验分析认为:通常采用的干粉灭火法从理论和生产实际来看都存在问题,细水雾法是适合火车装油过程初期火灾扑救的较好方法,具有安全高效的特点。     

诱导喷嘴改进滤筒脉冲清灰效果的实验研究

改善清灰效果是提高滤筒除尘效率的关键和难点问题。运用自制脉冲喷吹实验台,采用诱导喷嘴(超音速引流喷嘴和气流散射器)对325 mm×660 mm滤筒进行脉冲喷吹清灰实验研究,并与采用普通喷吹孔的实验结果进行比较分析,得出采用诱导喷嘴时侧壁正压力峰值平均值是普通喷吹孔的1.465倍;且采用诱导喷嘴时各测点的不均衡系数为0.768～1.336,普通喷口为0.270～2.251,而不均衡系数越接近于1,其清灰效果越好;同时,采用诱导喷嘴时各测点基本在同一时刻达到正峰值。实验充分表明采用诱导喷嘴确保了滤筒长度方向上内壁清灰压力的均匀性,且对滤筒清灰效果有明显的改善作用。     

济南市道路扬尘排放因子估算及其影响因素研究

以济南城市道路为研究对象,采用美国环保署AP-42模型和方法,通过道路分类、优化布点、样品采集、实地观测和计算分析,获得道路粉尘负荷及四种类型道路扬尘的排放因子,探讨了排放因子的主要影响因素。结果表明,路面粉尘负荷随车流量增大而逐渐降低,城市城区路面粉尘负荷多小于城市外围路面,且外围道路路面粉尘负荷随时间和空间变化大;支路和次干道排放因子相对较小,快速路排放因子较高,主干道排放因子最高,其TSP、PM10、PM2.5排放因子分别高达25.239 3 g/VKT、4.731 1 g/VKT、0.597 2 g/VKT;排放因子随平均车重增加呈现逐渐增大趋势;同种类型道路排放因子均随道路粉尘负荷的增加而增加;次干道和快速路排放因子随车流量增大而减小。所获结论可为城市道路扬尘排放估算提供参考。