立井揭煤前测定煤层瓦斯压力的方法与实践

为了解决复杂环境下立井揭煤前煤层瓦斯压力的可靠测定,基于揭煤井筒瓦斯地质特征、煤岩体物理力学性质,应用COMSOL软件模拟揭煤工作面在接近目标煤层时,井筒周围煤岩的地应力分布特征,直观展现了目标煤层中的应力分布结果。模拟结果表明,立井工作面距煤层的垂直距离为7 m时,煤层中会形成一个近似于环形的卸压圈,卸压半径为16 m,因此煤层瓦斯压力测试孔的终孔位置应布置在井筒中心线16 m以外的原始地应力区,以保证测压点瓦斯压力不受揭煤井筒卸压区的影响,令测压结果准确可靠,从而更好地预测煤与瓦斯突出区域的危险性。同时,结合立井揭煤工作面的水文地质特征和井筒严重淋水情况,自主研发并应用了瓦斯测压孔"两堵一注"封孔材料及特定的封孔工艺,进一步保障了封孔质量和瓦斯压力测试结果的可靠性。最后,依据测压结束时测压管内的实际水压情况,对测压结果进行修正,并依据实测瓦斯含量,采用间接法对所测得的瓦斯压力进行验证,实测值在反算得到的瓦斯压力值域内,表明此方法有效可行。     

Vegetation changes in Conservation Reserve Program lands in interior Alaska

Over 14 million hectares of erosion prone cropland in the United States has been converted into grasslands through the Conservation Reserve Program (CRP) administered by the United States Department of Agriculture, however, studies of the effects of CRP enrollment on plant communities and subsequent plant succession are largely lacking. In Delta Junction, Alaska plant communities in CRP fields are transitioning from grasslands to shrub dominated plant communities, which are resulting in compliance problems with program regulations that state “fields must be maintained in a condition that permits easy conversion to cropland”. To determine plant succession and how previous land management and soils might influence the transition, we measured plant populations in 20 CRP fields throughout Delta Junction using modified-Whittaker plots. These data were combined with data on current management practices, previous farming history, soils, soil properties, diversity indices, and time since land was cleared and analyzed with nonmetric multidimensional scaling ordination to determine factors that influence plant succession. Time in the CRP was the only factor consistently influencing plant succession. As time in the CRP increased, the planted introduced grasses brome grass (Bromus inermis) and red fescue (Festuca rubra) and the native pteridophyte (Equisetum arvense) decreased, whereas a native grass (Calamigrostis canadensis), five native forb, two native shrub, and three native tree species increased. Plant diversity increased at a rate of more than 2 species per 1000 m² per year. Regression analyses of plant species and plant groups using time in the CRP as the dependent variable resulted in the identification of outlier CRP fields with significantly more or less than expected covers of vegetation. All fields with these outliers had reasonable explanations for the differences in cover that were unrelated to the overall rate of plant succession. Current management practices will result in incompliant fields and different management practices that result in woody vegetation control is key to maintaining CRP fields in compliance.     

Evaluation of pliers’ grip spans in the maximum gripping task and sub-maximum cutting task

A total of 25 males participated to investigate the effects of the grip spans of pliers on the total grip force, individual finger forces and muscle activities in the maximum gripping task and wire-cutting tasks. In the maximum gripping task, results showed that the 50-mm grip span had significantly higher total grip strength than the other grip spans. In the cutting task, the 50-mm grip span also showed significantly higher grip strength than the 65-mm and 80-mm grip spans, whereas the muscle activities showed a higher value at 80-mm grip span. The ratios of cutting force to maximum grip strength were also investigated. Ratios of 30.3%, 31.3% and 41.3% were obtained by grip spans of 50-mm, 65-mm, and 80-mm, respectively. Thus, the 50-mm grip span for pliers might be recommended to provide maximum exertion in gripping tasks, as well as lower maximum-cutting force ratios in the cutting tasks.     

综采工作面人员操作可靠性与割煤机运行方式的选择与分析

应用人机工程及可靠性理论,分析了连续作业时间和割煤机运行方式对综采工作面人员操作可靠性的影响,建立了割煤机运行方式的优化模型。根据模型所选择的割煤机运行方式,既能提高工作面产量,也能提高人员操作可靠性,有利于综采工作面高效安全生产     

刈割对牧草地下部根区土壤养分及土壤酶活性的影响

对不同刈割强度对牧草地下部根区土壤养分状况及土壤酶活性进行了研究,结果表明,牧草刈割对根区土壤养分、土壤酶活性和土壤微生物数量存在一定影响。不同刈割强度对牧草根区土壤有机质、全磷和全钾含量无明显影响。土壤全氮、碱解氮、速效磷、速效钾含量均因刈割强度的增加而显著下降。土壤蔗糖酶、脲酶活性因刈割处理强度的增加而下降;土壤过氧化氢酶活性则表现为相反的变化趋势。刈割对土壤微生物总数量的影响较大,表现为轻刈割>不刈割>重刈割。     

不同地应力条件下直眼掏槽破岩的理论研究与数值模拟

为了研究不同地应力场对直眼掏槽破岩的影响,提出了基于Schwarz交替迭代法和弹性力学理论建立的掏槽区岩体的应力状态方程,同时对不同地应力条件下单孔直眼掏槽破岩过程进行了数值模拟。结果表明:在炸药爆炸前期和中期,初始地应力场对结果影响较小,主要是槽孔爆炸应力场起主导作用,在爆炸后期,初始地应力场对爆破后裂纹的扩展具有导向作用,裂纹扩展主方向趋向于最大初始地应力方向。进一步分析表明,岩体在初始地应力场与爆炸应力场共同作用后,在空孔和槽孔圆心连线上产生最大拉应力,并且在不同地应力条件下最大拉应力模拟值的发展趋势与理论计算较为一致。     

多晶硅切割液废液的回收与利用

结合工程实际,介绍了太阳能产业用多晶硅片切割过程中产生的割液废液的处理工艺及回收工艺,并分析了它的投资成本和经济效益。     

上海崇明东滩互花米草种子产量与活性对刈割的响应

有性繁殖与种子扩散是互花米草（Spartina alterniflora）侵入新生境的重要途径,抑制有性繁殖是有效控制互花米草进一步扩散与二次入侵的关键。文章研究了刈割对互花米草种子产量及其活性的影响,结果表明：四月（生长初期）1次刈割在一定程度上促进了互花米草的有性繁殖,其每穗种子数（481.3粒）、种子平均生活力（36.7%）与对照每穗种子数（425.5粒）和种子平均生活力（41.3%）间不存在显著差异,表现出超量补偿现象。四月和七月（扬花期）2次刈割与扬花期1次刈割能有效抑制互花米草的有性繁殖,其种子的生产量（每穗种子数分别为186.3和173.6粒）与活性（分别为18.0%和17.3%）较对照显著降低,表现出不足补偿现象。四月和七月2次刈割与七月扬花期1次刈割对互花米草有性繁殖的控制效果较好。在互花米草管理与控制实践中,扬花期刈割是有效控制互花米草有性繁殖与扩散的重要途径。     

水力割缝增透抽采煤层瓦斯原理及应用

煤层瓦斯抽采是避免煤矿瓦斯灾害发生的根本防治措施,水力割缝技术使煤体在割缝后应力松弛、卸压、破坏、破裂,以成倍或者十几倍地提高煤层的渗透性,继而对煤层瓦斯进行抽采,使瓦斯煤层变为低瓦斯或无瓦斯煤层,从根本上避免瓦斯灾害发生。从水力割缝技术切割煤层致煤层应力变化角度,将理论分析和数值模拟方法相结合,根据渗流力学平面径向流理论,分析给出水力割缝技术增透抽采瓦斯原理。以兖州东滩矿3号煤层为例,分析采用水力割缝技术前后煤层应力变化、渗透率变化规律。结果表明:大面积割缝后,应力重新分布,由均匀状态转变为非均匀状态分布,水平缝使煤层卸压,煤层应力普遍降低,在缝上部煤层局部形成拉应力区。割缝后渗透率是割缝前的4.34倍,渗透率大幅度增加,从而提高瓦斯抽采速度和最终抽采率。     

我国厨余垃圾资源化技术的多维绩效评价

随着我国大力推动生活垃圾分类管理工作,厨余垃圾的资源化利用受到越来越多关注.厨余垃圾资源化技术已有包括厌氧消化处理、好氧生物处理和昆虫饲料转化等类型,但在已有应用案例中存在资源化程度低、环境影响显著和经济效益差等诸多问题,缺乏技术绩效的系统化分析和综合性评价.为此,研究面向厨余垃圾资源化技术应用的全生命周期过程,构建了资源效率、环境影响、经济可行和社会效应的多维绩效评价指标体系(包括21项指标),以我国的14项典型技术应用项目为案例开展定量化综合评价研究.结果表明,厌氧消化和昆虫饲料转化处理技术的得分分别为58.39分和59.65分,高于好氧生物处理(49.16分);按细分技术类型,集中式黑水虻转化和中温湿式厌氧工艺得分较高,分别为67.14分和60.82分.按技术的处理规模和设施分布方式,集中式处理技术在资源效率和经济效益维度上分别比分散式技术高出13%和62%;分散式处理技术在环境影响和社会效应维度上比集中式高出8%和34%.在厨余垃圾资源化实践中,应结合当地的厨余垃圾理化性质、生活垃圾分类收集工作推进情况、财政承担能力和收运距离等多因素综合考量,因地制宜的选择适宜技术路线.