At a fully mechanized working face of a coal mine as prototype,we investigated,by simulation,the flow field and dust distribution during the process of its isolation by a curtain of air,using the CFD software, Fluent....At a fully mechanized working face of a coal mine as prototype,we investigated,by simulation,the flow field and dust distribution during the process of its isolation by a curtain of air,using the CFD software, Fluent.The results show that the air curtain installed on the shearer can effectively prevent the dust （especially the respirable dust）from diffusing into the work area of the operator,reducing the dust concentration on the side of the operator and greatly improving his working environment.The field application of the air curtain shows that the dust-isolation effect of an air curtain is quite noticeable.The isolation efficiency for respiratory dust is over 70%and,as well,it has good dust-isolation effect for nonrespiratory dust.The air curtain is a useful way to resolve the problem of dust-isolation at a fully mechanized working face.It has a practical background elsewhere with more extensive applications.展开更多
This paper presents a variational method for the fuse-warhead coordination design of an air-faced missile, which takes the distribution density of fragments for a variable and the totalprobability of kill of single mi...This paper presents a variational method for the fuse-warhead coordination design of an air-faced missile, which takes the distribution density of fragments for a variable and the totalprobability of kill of single missile against an air-target for an objective function.展开更多
A combined method of numerical simulation and field testing was adopted in this study in the interest of solving the problem of hard to control high concentrate dusts on a fully mechanized mining face. In addi- tion, ...A combined method of numerical simulation and field testing was adopted in this study in the interest of solving the problem of hard to control high concentrate dusts on a fully mechanized mining face. In addi- tion, the dust suppression effect of a multi-direction whirling air curtain was studied in this paper. Under the influence of the wall attachment effect, the compressed air which blows out from the two-phase or three-phase radial outlets on the generator of the air curtain can form a multi-direction whirling air curtain, which can cover the whole roadway section of a fully mechanized mining face. The traditional method of controlling dust is a forcing system with exhaust overlap which has the major disadvantage of lacking a jet effect and consequently results in poor dust control. It is difficult to form the air flow field within the range of Lp ≤ 5√S. However, due to the effect of this novel system, the radial airflow can be turned into axial airflow allowing fresh air to flow through the length of the heading. The air flow field which is good at controlling dust diffusion can be formed 12.8 m from the heading face. Furthermore, the field measurement results show that before the application of a multi-direction whirling air curtain, the dust concentration is 348.6 mg/m^3 and 271.4 mg/m^3 respectively at the roadway cross-section measurement points which are 5 m and 10 m from the heading face. However, after the application of the multi-direction whirling air curtain, the dust concentration is only 61.2 mg/m3 and 14.8 mg/m^3, respectively. Therefore, the dust control effect of a multi-direction whirling air curtain is obvious.展开更多
Carbon dioxides (CO<sub>2</sub>) concentration has become much higher every year and this has already become the global issue. Lichen is a symbiotic organism that is best known as the air pollution indicat...Carbon dioxides (CO<sub>2</sub>) concentration has become much higher every year and this has already become the global issue. Lichen is a symbiotic organism that is best known as the air pollution indicator. Based on its frequency and diversity distribution, the level of pollution that has been made can be determined. This re-search was conducted in UKM Fernarium Free Air Carbon Dioxides Enrichment Station (FACE Station) with lichen frequencies and diversities observed and analyzed statistically and graphically. Seven species of li-chens were found at the sampling locations. Findings showed that there was significant relationship in lichen frequency and diversity distribution under elevated CO<sub>2</sub> inside FACE Station with its surrounding.展开更多
人类活动导致的大气和气候变化将极大地改变作物的生长环境,其中最大的一个变化就是大气二氧化碳(CO2)浓度的迅速上升:从工业革命前的平均270μmol/mol上升到目前的381μmol/mol,到2050年至少超过550μmol/mol。FACE(Free-air CO2 enric...人类活动导致的大气和气候变化将极大地改变作物的生长环境,其中最大的一个变化就是大气二氧化碳(CO2)浓度的迅速上升:从工业革命前的平均270μmol/mol上升到目前的381μmol/mol,到2050年至少超过550μmol/mol。FACE(Free-air CO2 enrichment,开放式空气中CO2浓度增高)试验是目前评估未来高浓度CO2对作物生长和产量实际影响的最佳方法。水稻无疑是人类最重要的食物来源,迄今为止人类利用FACE技术开展水稻响应和适应的研究已有10a(19982008年)的历史。以生长发育为主线,首次系统综述了10a水稻FACE试验在该领域的研究成果,总结了FACE情形下高浓度CO2(模拟本世纪中叶大气CO2浓度)对主要供试水稻品种(小区面积大于4m2)光合作用、生育进程、地上部生长、地下部生长、物质分配、籽粒灌浆、产量构成以及倒伏性状等影响的研究进展,比较了FACE与非FACE研究之间以及中国和日本FACE研究(世界上唯一的两个大型水稻FACE研究)之间的异同点。根据研究进展以及当前的技术水平,文章最后提出了该领域的3个优先课题:(1)FACE情形下杂交稻生产力响应高于预期的生物学机制;(2)FACE情形下CO2与主要栽培措施的互作效应;(3)FACE情形下CO2与主要空气污染物臭氧的互作效应。这些响应的机理性解析将有助于从根本上减少人类预测未来粮食安全的不确定性,进而更加有效地制订出应对全球变化的适应策略。展开更多
联合国政府间气候变化专业委员会(IPCC)最新报告预测20世纪中叶全球大气二氧化碳(CO2)浓度将由目前的381μmolmol-1至少上升到550μmolmol-1,CO2浓度不断升高将对世界粮食生产和安全产生深刻影响。与封闭和半封闭气室相比,FACE(FreeAir ...联合国政府间气候变化专业委员会(IPCC)最新报告预测20世纪中叶全球大气二氧化碳(CO2)浓度将由目前的381μmolmol-1至少上升到550μmolmol-1,CO2浓度不断升高将对世界粮食生产和安全产生深刻影响。与封闭和半封闭气室相比,FACE(FreeAir CO2 Enrichment,开放式空气中CO2浓度增高)技术平台,在完全开放的大田条件下运行,代表了人们对未来高CO2浓度环境的最好模拟。水稻是世界上最重要的粮食作物之一,在过去10a中(1998～2007年),全球有两个大型水稻FACE平台(直径12m)在运行,一个在温带地区的日本岩手,另一个在亚热带地区的中国江苏。以FACE研究为重点,系统收集和整理了高CO2浓度对水稻产量影响的研究进展,比较了FACE与各种气室研究结果的异同点,评估了CO2与生物(品种、病虫和杂草)和非生物因子(肥料、水分、温度和臭氧)的互作效应,提出了未来大气CO2浓度升高情形下水稻生产的适应策略,并讨论了该领域有待深入研究的方向。展开更多
开放式大气CO2浓度增加(Free-air CO2 Enrichment,FACE)的处理普遍降低了作物含氮率,研究作物体内各种氮形态尤其是可溶蛋白的含量特征,对于解析FACE条件下氮代谢机制具有重要意义。在大田栽培条件下,研究了开放式大气CO2浓度增加200μm...开放式大气CO2浓度增加(Free-air CO2 Enrichment,FACE)的处理普遍降低了作物含氮率,研究作物体内各种氮形态尤其是可溶蛋白的含量特征,对于解析FACE条件下氮代谢机制具有重要意义。在大田栽培条件下,研究了开放式大气CO2浓度增加200μmol.mol-1的处理对粳稻品种武香粳14各生育期功能叶片及根系可溶蛋白含量的影响。结果表明:(1)FACE处理显著增加了高、中氮水平下抽穗期顶叶的可溶蛋白含量,增幅分别为4%和7%,相反,不同氮水平下成熟期顶叶可溶蛋白含量显著低于对照,而拔节期及孕穗期顶叶可溶蛋白含量与对照无显著差异;(2)FACE处理显著提高了高、中氮水平下抽穗期倒二叶可溶蛋白的含量,增幅分别为16%和14%,但明显降低了不同氮水平下拔节期、孕穗期和成熟期倒二叶可溶蛋白的含量;(3)FACE处理显著提高了拔节期、孕穗期和抽穗期根系可溶蛋白的含量,增幅分别达18%、19%和12%,而成熟期根系可溶蛋白含量与对照无显著差异;(4)CO2和N处理对水稻拔节期、抽穗期和成熟期倒二叶以及抽穗期剑叶可溶性蛋白含量的互作效应均达显著或极显著水平。在此基础上,对FACE条件下功能叶片及根可溶蛋白含量变化的可能机制进行了讨论。展开更多
近地层臭氧(O3)浓度升高使作物生长发育受到抑制进而使产量下降,但O3胁迫条件下作物抗倒性状的变化及其可能原因均不清楚。FACE(Free Air gas Concentration Enrichment)试验在很少扰动的自然农田实施,其特有的空间优势为研究这一问题...近地层臭氧(O3)浓度升高使作物生长发育受到抑制进而使产量下降,但O3胁迫条件下作物抗倒性状的变化及其可能原因均不清楚。FACE(Free Air gas Concentration Enrichment)试验在很少扰动的自然农田实施,其特有的空间优势为研究这一问题提供了最好的机会。依托全球唯一的稻田臭氧FACE技术平台,以杂交稻两优培九为供试材料,设置大气背景O3浓度和高O3浓度两个水平首次对这一问题进行了实验研究。结果表明:高O3浓度使水稻抽穗期单茎(去除叶鞘)倒5、倒4和倒3节间的平均倒伏指数分别增加25%、16%和14%,使抽穗后35 d对应节间倒伏指数分别增加13%、12%和2%,除抽穗后35 d倒3节间外均达显著或极显著水平;高浓度O3使水稻抽穗期和抽穗后35 d植株倒5、倒4和倒3节间的抗折力和弯曲力矩均下降,前者降幅明显大于后者;高O3浓度对抽穗期和抽穗后35 d倒5、倒4、倒3和倒2和倒1节间的长度和粗度影响较小,但使各节间单位长度鲜重和干重一致下降,以单位长度干重降幅更大;高O3浓度使结实期倒5、倒4、倒3、倒2和倒1节间可溶性糖和淀粉含有率均下降,抽穗后35 d降幅大于抽穗期。以上数据表明,未来高浓度臭氧环境条件下两优培九结实期的倒伏风险明显增加,这主要与基部节间抗折能力明显削弱有关,而后者可能又与节间充实程度下降有关。展开更多
基金Financial support for this work,provided by the National Natural Science Foundation of China(No.50974060)the State Safety Production Science and Technology Development Plan (No.06-396)
文摘At a fully mechanized working face of a coal mine as prototype,we investigated,by simulation,the flow field and dust distribution during the process of its isolation by a curtain of air,using the CFD software, Fluent.The results show that the air curtain installed on the shearer can effectively prevent the dust （especially the respirable dust）from diffusing into the work area of the operator,reducing the dust concentration on the side of the operator and greatly improving his working environment.The field application of the air curtain shows that the dust-isolation effect of an air curtain is quite noticeable.The isolation efficiency for respiratory dust is over 70%and,as well,it has good dust-isolation effect for nonrespiratory dust.The air curtain is a useful way to resolve the problem of dust-isolation at a fully mechanized working face.It has a practical background elsewhere with more extensive applications.
文摘This paper presents a variational method for the fuse-warhead coordination design of an air-faced missile, which takes the distribution density of fragments for a variable and the totalprobability of kill of single missile against an air-target for an objective function.
基金supported by the Key Program of the Coal Joint Funds of the National Natural Science Foundation of China (No.U1261205)the Youth Program of National Natural Science Foundation of China (No.51404147)+2 种基金the Class General Financial Grant from the China Postdoctoral Science Foundation (No.2015M570601)the Scientific Research Foundation of Shandong University of Science and Technology for Recruited Talents (No.2014RCJJ029)the State Key Laboratory of Mining Disaster Prevention and Control Co-founded by Shandong Province and the Ministry of Science and Technology,Shandong University of Science and Technology (No.MDPC2013ZR02)
文摘A combined method of numerical simulation and field testing was adopted in this study in the interest of solving the problem of hard to control high concentrate dusts on a fully mechanized mining face. In addi- tion, the dust suppression effect of a multi-direction whirling air curtain was studied in this paper. Under the influence of the wall attachment effect, the compressed air which blows out from the two-phase or three-phase radial outlets on the generator of the air curtain can form a multi-direction whirling air curtain, which can cover the whole roadway section of a fully mechanized mining face. The traditional method of controlling dust is a forcing system with exhaust overlap which has the major disadvantage of lacking a jet effect and consequently results in poor dust control. It is difficult to form the air flow field within the range of Lp ≤ 5√S. However, due to the effect of this novel system, the radial airflow can be turned into axial airflow allowing fresh air to flow through the length of the heading. The air flow field which is good at controlling dust diffusion can be formed 12.8 m from the heading face. Furthermore, the field measurement results show that before the application of a multi-direction whirling air curtain, the dust concentration is 348.6 mg/m^3 and 271.4 mg/m^3 respectively at the roadway cross-section measurement points which are 5 m and 10 m from the heading face. However, after the application of the multi-direction whirling air curtain, the dust concentration is only 61.2 mg/m3 and 14.8 mg/m^3, respectively. Therefore, the dust control effect of a multi-direction whirling air curtain is obvious.
文摘Carbon dioxides (CO<sub>2</sub>) concentration has become much higher every year and this has already become the global issue. Lichen is a symbiotic organism that is best known as the air pollution indicator. Based on its frequency and diversity distribution, the level of pollution that has been made can be determined. This re-search was conducted in UKM Fernarium Free Air Carbon Dioxides Enrichment Station (FACE Station) with lichen frequencies and diversities observed and analyzed statistically and graphically. Seven species of li-chens were found at the sampling locations. Findings showed that there was significant relationship in lichen frequency and diversity distribution under elevated CO<sub>2</sub> inside FACE Station with its surrounding.
文摘人类活动导致的大气和气候变化将极大地改变作物的生长环境,其中最大的一个变化就是大气二氧化碳(CO2)浓度的迅速上升:从工业革命前的平均270μmol/mol上升到目前的381μmol/mol,到2050年至少超过550μmol/mol。FACE(Free-air CO2 enrichment,开放式空气中CO2浓度增高)试验是目前评估未来高浓度CO2对作物生长和产量实际影响的最佳方法。水稻无疑是人类最重要的食物来源,迄今为止人类利用FACE技术开展水稻响应和适应的研究已有10a(19982008年)的历史。以生长发育为主线,首次系统综述了10a水稻FACE试验在该领域的研究成果,总结了FACE情形下高浓度CO2(模拟本世纪中叶大气CO2浓度)对主要供试水稻品种(小区面积大于4m2)光合作用、生育进程、地上部生长、地下部生长、物质分配、籽粒灌浆、产量构成以及倒伏性状等影响的研究进展,比较了FACE与非FACE研究之间以及中国和日本FACE研究(世界上唯一的两个大型水稻FACE研究)之间的异同点。根据研究进展以及当前的技术水平,文章最后提出了该领域的3个优先课题:(1)FACE情形下杂交稻生产力响应高于预期的生物学机制;(2)FACE情形下CO2与主要栽培措施的互作效应;(3)FACE情形下CO2与主要空气污染物臭氧的互作效应。这些响应的机理性解析将有助于从根本上减少人类预测未来粮食安全的不确定性,进而更加有效地制订出应对全球变化的适应策略。
文摘联合国政府间气候变化专业委员会(IPCC)最新报告预测20世纪中叶全球大气二氧化碳(CO2)浓度将由目前的381μmolmol-1至少上升到550μmolmol-1,CO2浓度不断升高将对世界粮食生产和安全产生深刻影响。与封闭和半封闭气室相比,FACE(FreeAir CO2 Enrichment,开放式空气中CO2浓度增高)技术平台,在完全开放的大田条件下运行,代表了人们对未来高CO2浓度环境的最好模拟。水稻是世界上最重要的粮食作物之一,在过去10a中(1998～2007年),全球有两个大型水稻FACE平台(直径12m)在运行,一个在温带地区的日本岩手,另一个在亚热带地区的中国江苏。以FACE研究为重点,系统收集和整理了高CO2浓度对水稻产量影响的研究进展,比较了FACE与各种气室研究结果的异同点,评估了CO2与生物(品种、病虫和杂草)和非生物因子(肥料、水分、温度和臭氧)的互作效应,提出了未来大气CO2浓度升高情形下水稻生产的适应策略,并讨论了该领域有待深入研究的方向。
文摘开放式大气CO2浓度增加(Free-air CO2 Enrichment,FACE)的处理普遍降低了作物含氮率,研究作物体内各种氮形态尤其是可溶蛋白的含量特征,对于解析FACE条件下氮代谢机制具有重要意义。在大田栽培条件下,研究了开放式大气CO2浓度增加200μmol.mol-1的处理对粳稻品种武香粳14各生育期功能叶片及根系可溶蛋白含量的影响。结果表明:(1)FACE处理显著增加了高、中氮水平下抽穗期顶叶的可溶蛋白含量,增幅分别为4%和7%,相反,不同氮水平下成熟期顶叶可溶蛋白含量显著低于对照,而拔节期及孕穗期顶叶可溶蛋白含量与对照无显著差异;(2)FACE处理显著提高了高、中氮水平下抽穗期倒二叶可溶蛋白的含量,增幅分别为16%和14%,但明显降低了不同氮水平下拔节期、孕穗期和成熟期倒二叶可溶蛋白的含量;(3)FACE处理显著提高了拔节期、孕穗期和抽穗期根系可溶蛋白的含量,增幅分别达18%、19%和12%,而成熟期根系可溶蛋白含量与对照无显著差异;(4)CO2和N处理对水稻拔节期、抽穗期和成熟期倒二叶以及抽穗期剑叶可溶性蛋白含量的互作效应均达显著或极显著水平。在此基础上,对FACE条件下功能叶片及根可溶蛋白含量变化的可能机制进行了讨论。
文摘近地层臭氧(O3)浓度升高使作物生长发育受到抑制进而使产量下降,但O3胁迫条件下作物抗倒性状的变化及其可能原因均不清楚。FACE(Free Air gas Concentration Enrichment)试验在很少扰动的自然农田实施,其特有的空间优势为研究这一问题提供了最好的机会。依托全球唯一的稻田臭氧FACE技术平台,以杂交稻两优培九为供试材料,设置大气背景O3浓度和高O3浓度两个水平首次对这一问题进行了实验研究。结果表明:高O3浓度使水稻抽穗期单茎(去除叶鞘)倒5、倒4和倒3节间的平均倒伏指数分别增加25%、16%和14%,使抽穗后35 d对应节间倒伏指数分别增加13%、12%和2%,除抽穗后35 d倒3节间外均达显著或极显著水平;高浓度O3使水稻抽穗期和抽穗后35 d植株倒5、倒4和倒3节间的抗折力和弯曲力矩均下降,前者降幅明显大于后者;高O3浓度对抽穗期和抽穗后35 d倒5、倒4、倒3和倒2和倒1节间的长度和粗度影响较小,但使各节间单位长度鲜重和干重一致下降,以单位长度干重降幅更大;高O3浓度使结实期倒5、倒4、倒3、倒2和倒1节间可溶性糖和淀粉含有率均下降,抽穗后35 d降幅大于抽穗期。以上数据表明,未来高浓度臭氧环境条件下两优培九结实期的倒伏风险明显增加,这主要与基部节间抗折能力明显削弱有关,而后者可能又与节间充实程度下降有关。
