考虑采空区压实效应的沿空掘巷煤柱设计方法研究*

为建立1种相对科学的沿空掘巷煤柱尺寸设计方法,采用理论与数值试验研究、现场试验等手段,基于采空区压实效应,分析各尺寸煤柱沿空掘巷掘采全过程围岩应力分布与变形。研究结果表明:采空区压实效应模拟研究方法能够模拟采空区应力恢复;掘巷过程中,煤柱内应力由小到大依次为:工作面倾向水平应力、工作面推进方向水平应力、垂直应力,在小尺寸煤柱内呈偏向采空区一侧的单峰分布,小尺寸煤柱逐渐向大尺寸煤柱过渡期间,内部应力量值开始比原岩应力小,随后逐渐增加至出现一定的应力集中,而实体煤帮中峰值应力不断降低,位置逐步向巷帮转移;受超前采动作用后,更大面积的煤柱会受高应力作用,大尺寸煤柱内垂直及水平应力集中系数逐步提高,工作面倾向的高应力区范围更广,当煤柱宽度不超过一定数值时,内部应力大小均低于掘巷过程中相应数值,大煤柱则具有相反的规律,实体煤帮中应力集中系数与掘巷时相比更大,峰值点向围岩深处进一步转移;研究结果通过工程实践检验,可为合理煤柱尺寸设计提供1种新的方法。     

黄淮海地区干热风灾害致灾因子时空特征分析

黄淮海地区是我国冬小麦主产区,也是干热风灾害危害最重、影响最广的地区,本研究利用黄淮海冬麦主产区81个站点1961-2017年的逐日气象数据和冬小麦生育期资料,分析了该地区小麦成熟期和干热风致灾因子的时空变化特征。在81个测站中,有23个成熟期提前趋势显著或极显著,但大部地区成熟期变化趋势不显著,有63%的站点未通过显著性检验。对干热风致灾因子达标日数和相似系数的分析表明,达到干热风灾害阈值的概率依次为14:00风速>14:00相对湿度>日最高气温,最高气温是形成干热风的主要限制因素,轻干热风的发生最高气温和相对湿度起主要作用,重干热风则是高温胁迫起决定作用,低湿条件使胁迫加重,风速只起辅助作用。揭示了该地区干热风危害总体减轻的气象条件基础,即干热风3要素表现为最高气温略降、14:00相对湿度略增、14:00风速明显减小的特征,3要素均向有利于减轻干热风发生的方向变化,对于冬小麦籽粒灌浆和产量形成是有利的。但灌浆成熟期内最低气温的显著升高,意味着气温日较差减小、小麦夜间呼吸消耗增大,对其干物质积累和产量形成带来潜在不利影响。     

Starting improvement of micro-wind turbines operating in low wind speed regions

The study deals with the design and optimization of external and internal geometry of micro-wind turbines blades. A specified objective function which consists of the power coefficient and the starting time was defined and the genetic algorithm optimization technique in conjunction with the blade-element momentum theory was adopted to find the geometry of the blades including the distributions of the chord, the twist angle and also the shell thickness. Moreover, the allowable stress of the blades was considered as a constraint to the objective function. Results show that a reasonable compromise is achievable such that the starting time of the blades reduces noticeably in return for a small drop in the power coefficient. The significant improvement of the hollow blades over the solid ones indicates that the power coefficient and the starting performance could be improved through the appropriate distributions of the considered decision variables, i.e. the chord, the twist angle and also the shell thickness.     

影响危险化学品生产企业安全评价有效性的因素探讨

随着化学工业的迅速发展,化学品的产量和品种大幅增加,危险化学品生产企业各类事故频发,严重阻碍了化学工业的发展.为此,国家制定了一系列的法律法规,以期遏制恶性事故的发生.安全评价作为预防事故的重要手段,现已广泛应用于各个行业,危险化学品生产企业也不例外.但是,随着安全评价工作的开展,也暴露出与安全评价有关的一些问题.本文简要介绍了我国危险化学品生产企业的安全现状,详细分析了影响危险化学品生产企业安全评价有效性的各种因素,并提出了相应的对策措施.     

燃煤烟气中CO_2脱除方法的分析与探讨

作为主要的温室气体,CO2减排问题引起全球范围的广泛关注。阐述了燃煤烟气中CO2脱除的多种方法,分析比较了CO2的吸收法、吸附法、膜分离法等的特点及各自的优缺点,侧重介绍了有机胺和氨水脱除的技术进展,并介绍了氨水烟气脱碳的部分试验结果。     

Effect of cadmium alone and in combination with butachlor on soil enzymes

The ecological toxicity of cadmium (Cd, 10 mg kg⁻¹ of dry weight soil) and butachlor (10, 50 and100 mg kg⁻¹ of dry weight soil) in both their single and combined effects on soil urease and phosphatase was studied after 1, 3, 7, 14, 21 and 28 days exposure under controlled conditions in paddy and phaeozem soils. The results showed that Cd reduced the activities of urease and phosphatase at early incubation time (1–7 days), while the reduction almost disappeared at the end of the incubation. The effect of Cd on phosphatase was more pronounced than that on urease. The activities of urease and phosphatase were reduced by butachlor, while urease activity was significantly (P < 0.05 or P < 0.01) improved when the concentrations of butachlor were 10 and 50 mg kg⁻¹ at the end of the incubation. When Cd (10 mg kg⁻¹) was combined with butachlor (50 and 100 mg kg⁻¹), the activities of urease and phosphatase became lower than without combination at early incubation time, which indicated that the toxicity of Cd significantly increased (P < 0.05 or P < 0.01). However, when Cd (10 mg kg⁻¹) was combined with butachlor (10 mg kg⁻¹), the activities of urease and phosphatase became higher than those without combination at the end of the incubation, which indicated that the toxicity of Cd decreased. It was indicated that the combined effects depended largely on the incubation time and the concentration ratio of Cd and butachlor. In addition, it was showed that the combined effects of butachlor and Cd appeared different in paddy from phaeozem, which may be related to the different properties of these soils.     

壬基酚与壬基酚聚氧乙烯醚对多刺裸腹溞的复合毒性效应

为了探讨壬基酚聚氧乙烯醚（NP10EO）与其降解产物壬基酚（NP）对多刺裸腹溞的复合毒性效应,在实验室条件下研究了NP和NP10EO单一暴露对多刺裸腹溞的急性毒性和亚慢性毒性,以及两者混合暴露对多刺裸腹溞的联合毒性效应。结果表明：NP和NP10EO两种物质单一暴露对多刺裸腹溞的24 h LC50分别为0.154和3.37 mg.L-1,48 h LC50分别为0.065和2.11 mg.L-1。联合毒性实验中,定义0.5×LC50（NP）＋0.5×LC50（NP10EO）为一个毒性单位（1TU）。NP和NP10EO混合暴露后对多刺裸腹溞的24 h和48 h的LC50分别是0.646TU和0.291TU,联合毒性强度明显高于两种物质单一暴露时的毒性强度。在持续混合暴露条件下,多刺裸腹溞的首次生殖时间延迟、母体体长和初生幼体体长严重缩短、首次生殖数量大幅减少。说明NP和NP10EO对多刺裸腹溞的复合毒性表现出明显的协同效应。     

不同混凝剂在水厂原水处理中的混凝效果比较

针对水厂原水水质情况,对4种不同混凝剂的污染物去除效果进行了试验对比,研究不同混凝剂用于水厂原水处理的混凝效果．为优化后续工艺提供依据。     

棘洪滩水库典型风况分析及其应用研究

棘洪滩水库的源水是水库流场变化的主要动力,风力状况也是影响棘洪滩水库流场况变化的重要因素,当水库处于非调水期,风力状况的作用尤为明显。本论文整理了棘洪滩水库1989-2008年20年间气象资料,统计得出水库年际和四个季度的风向、风力变化情况。结果表明,棘洪滩水库常年盛行风向是南风和西北风。春季和冬季以西北风为主,夏季和秋季以东风和东南风为主。通过sMs软件建立的水质模型可以验证,不同的风向与风力大小对水库流场的变化有着显著的影响。     

大亚湾水体营养盐分布特征及其生态环境效应

2019年秋季和2020年春季在大亚湾海域开展了生态环境现状调查,调查要素包括水温、盐度、pH、溶解氧、化学需氧量(COD)、溶解无机氮(DIN)、磷酸盐(DIP)、叶绿素a等。秋季DIN和DIP平均浓度分别为(5.00±3.36)、(0.31±0.56) μmol/L,春季分别为(3.12±1.97)、(0.13±0.05) μmol/L,春季DIN和DIP含量低于秋季。秋、春季DIN和DIP高值区均位于淡澳河入海口、哑铃湾和范和港湾口以及渔业养殖和港口交汇海域,且呈现自湾顶至湾口逐渐减小趋势,主要受入海径流、外海水入侵、渔业养殖、污水排放等多重因素影响。大部分海域处于贫营养化状态,仅湾顶局部海域为中度富营养化水平。春季叶绿素a平均值为(2.10±1.07) μg/L,大于秋季[(0.83±0.54) μg/L],秋、春季叶绿素a空间分布大体与营养盐相同,即湾顶高,湾中和湾口逐渐降低,秋、春季N/P平均值分别为30.52±20.09和26.68±17.70,湾顶浮游植物繁殖的主要限制因子为磷,湾口的主要限制因子为氮。