178 resultados para 306-U1313C
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在现代工业生产过程中,螺纹联接由于稳定可靠、拆卸方便,而广泛应用于众多的机构装配当中。目前在中国,由于传统工艺和技术水平的原因,广泛应用在装配线上的是气动与液压扳手,其存在操作不方便、工人劳动强度大、效率低、角度和扭矩控制精度差,无法实现集中式管理等缺点。这也逐渐成为制约我国装备制造业发展的重要瓶颈。随着近几年装备制造业的飞速发展,对螺纹装配的效率和质量提出了更高的要求,自动螺纹拧紧机由于其装配效率高、控制精确、能够实现网络化等优点,逐渐应用于发动机、制冷压缩机、变速箱、机床、仪表等对螺纹拧紧的角度和位置精度要求很高的场合。但目前,我国所使用的自动螺纹拧紧机还完全依赖于国外,国内在自动螺纹拧紧机的研制和设计上才刚刚起步,同国外相比还存在着较大的差距。 本论文适应装备制造业的发展和自动螺纹拧紧设备市场的需要,根据现代螺纹拧紧理论与技术的发展情况,对自动螺纹拧紧机进行了深入研究。本论文结合嵌入式技术,设计出了基于嵌入式微控制器的螺纹拧紧机机轴控制器。 论文的第一部分介绍了自动螺纹拧紧机国内外发展现状,在此基础上,提出了本课题的研究目标与研究内容。 第二部分详细分析了现代螺纹拧紧理论。在此基础上,给出了在机轴控制器上实现精确预紧力控制的控制算法、包括紧固扭矩的计算、转角的计算、屈服点的计算等问题。同时,在扭矩控制中采用角度监视;在转角控制中采用扭矩监视;在屈服极限控制中采用扭矩监视和角度监视。可以自动对最终拧紧结果的有效性进行判断,从而实现有效、准确的螺纹多目标控制方式。本论文实现了扭矩控制/角度监视、转角控制/扭矩监视、屈服极限控制/扭矩、角度监视。 第三部分介绍了机轴控制器的硬件结构。本文采用美国Silicon Lab公司的C8051F040微控制器,使得成本大大降低。在硬件设计中采用大量可靠性设计,保证了螺纹拧紧机在复杂的工业环境下能够稳定工作。 第四部分介绍了机轴控制器的软件设计。在机轴控制软件的实现中,引入了嵌入式实时操作系统 C/OS-II。这部分首先将 C/OS-II移植到单片机C8051F040上,接着在 C/OS-II上完成整个机轴控制软件的编写。 C/OS-II的使用使得上层应用程序容易设计和扩展,提高了机轴控制软件的实时性。 实验证明,本文设计的基于嵌入式微控制器的螺纹拧紧机机轴控制器,控制精度较高、性能稳定、质量可靠、操作简便。在扭矩控制模式下,误差可以控制在5%以内;在屈服极限控制模式下,误差可以控制在15%以内。同时,由于在控制软件的设计中引入了嵌入式实时操作系统 C/OS-II, 使得该控制系统具有较好的扩展性和实时性。本设计进一步缩小了我国与国外同类产品的差距,因此,具有很好的市场发展前景。
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使用YJ-3000t紧装式六面顶高压设备和1260阻抗/增益-相位分析仪,在1.0~4.0GPa和773~1134K下用阻抗谱法就位测定了辉石岩的电导率。实验结果表明,电导率对频率具有很强的依赖性;温度是决定辉石岩电导率的一个重要物理参数,电导率随着温度升高而增大,lgσ与I/T之间符合Arrenhius关系式;随着压力升高。电导率降低,活化焓和独立于温度的指前因子亦降低。
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喀斯特石漠化代表了世界上一个比较独特的荒漠类型,即湿润区石质荒漠化。目前石漠化面积快速扩展的总体趋势并没有得到有效遏止,因对石漠化发生机制与喀斯特生态系统稳定性机制还不清楚,同时缺乏比较完善的石漠化防治理论和技术体系也是重要的原因之一。较为详细地介绍了目前西南喀斯特山区石漠化过程和适应性生态修复研究方面存在的基础理论问题,包括喀斯特石漠化的时空格局变化与驱动力、喀斯特山地的侵蚀过程、驱动力与危险性、以水为纽带的喀斯特生态系统退化和石漠化过程中的生物地球化学过程、喀斯特受损生态系统的适应性修复、喀斯特生态系统的服务功能优化和综合调控等方面,阐述了上述几个研究领域的研究现状与可能的发展方向;强调喀斯特石漠化是一个非地带性问题,不是纯自然过程,而是与自然、社会与经济紧密相关,需要以喀斯特科学为主的多学科交叉与综合集成研究。
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贵州茂兰喀斯特原始森林地区25个雨水样品的化学组成研究表明,该区雨水的pH值为4.4~7.2,平均为5.1。雨水样品富NH4^+、Ca^2+和SO4^2-、C1^-。NH4^+是最主要的阳离子,平均值为56.8/μmol/L,占阳离子组成的26%~74%,Ca^2+次之,平均值为14.8μmol/L,NHg和Ca^2+之和占了阳离子组成的71%~94%,SO4^2-是最主要的阴离子,平均值为39.2μmol/L,占了阴离子组成的69%~91%,CI一次之,平均值为9.5μmol/L。SO4^2-和C1-占了阴离子组成的71%~96%。与中国其他地区的雨水样品相比,茂兰地区雨水离子含量要低1~2个数量级;物质来源分析表明茂兰地区雨水中溶质主要来源于自然过程的输入,人为活动输入可以忽略不计.
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系统地收集和分析IAEA/WMO数据库GNIP/ISOHIS与文献报道的中国及周边大气降水和石笋的δ^18O等数据,发现大气降水δ^18O值和降水量效应在大尺度上均与前人研究结果相似,但在小尺度上具有显著的区域性特征:以塔里木盆地、鄂尔多斯盆地和潢川-合肥盆地等为中心的区域大气降水δ^18O值明显高于其它地区,而以拉萨和川-滇-黔为中心的区域明显低于其它地区;在川-滇-黔三省交界地区和湖南中东部分别出现了强和弱降水量效应。大气降水出现δ^18O较高值或降低值的主要原因可能与当地蒸发和季风等因子控制的水汽来源特征有关;而降水量效应的区域性特征可能与水汽来源结构变化密切相关。对区域上的大气降水和石笋δ^18O进行比较分析表明,以单一水汽来源为主的地区,石笋δ^18O值能较好地反映太阳辐射强度或季风强度;两种水汽来源强度相当的地区,石笋δ^18O值反映的是两种水汽来源的综合信息;在太阳辐射强度变化对不同水汽影响差异性明确之前很难直接解析为太阳辐射或季风强度信息.
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通过改进的连续浸提技术,把土壤钙的赋存形态划分为5个类型:水溶态、交换态、酸溶态、有机结合态及残渣态,用原子吸收光谱法测定各形态钙含量及总钙量,各形态钙的加和值与测得的总钙量基本相符,且各形态钙8次浸提的相对标准偏差基本在10%以内。探讨了改进的连续浸提方法提取条件(包括浸提剂、水土比、提取时间、离心速率及离心时间等)对提取效果的影响。结果表明,土壤中各形态钙可以满足生态地球化学土壤样品评价需要。
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多氯联苯(PCBs)是一种具有亲脂性、低水溶性、高稳定性和高生物富集性等特性的持久性有机污染物(POPs),而沉积物作为疏水性有机污染物(HOCs)的重要地质宿体,PCBs在POPs中发生的环境过程是研究的热点。本文综述国内外近几年来沉积物中PCBs分析测定以及迁移转化的研究动态,并对今后PCBs污染的生物修复研究提出了自己的见解.
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构建了贵州20世纪80年代、90年代和21世纪初等3期历史石漠化数据,利用其空间变换和数学模型详细探讨和评价了石漠化的时空演变过程,研究发现:(1)研究时段内贵州省石漠化总面积变化不明显,但石漠化内部类型之间的相互演变非常显著,各类型之间的演变具有转移、多变、“此消彼长”的特点。(2)石漠化的时空演变过程可分为单变方式、层变方式、返变方式等3种基本类型,其中以层变方式为主,单变方式为辅,返变方式较少。(3)石漠化正向演变与逆向演变并存,治理速度赶不上恶化速度,两者的比值为82.29%,局部治理,整体恶化。(4)各石漠化类型总的演变速率是398.31km^2·a^-1,石漠化等级越高,演变速率越慢。(5)石漠化演变频率最快的是中度石漠化和潜在石漠化,轻度石漠化的演变频率明显低于中度石漠化。对石漠化的空间演变区域特征和影响因子做了宏观的定性分析、并根据石漠化演变特点对综合治理提出了相应的建议。
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研究区内火山岩从基性—中性—中酸性都有出露,包括橄榄玄武岩、安山岩和英安岩,且都属于非碱性系列。通过对主元素和微量元素的研究,认为本区火山岩为滞后型弧(陆缘弧)火山作用的产物。源区由于存在大量的因俯冲作用进入地幔的陆壳物质以及流体的交代作用,从而出现富含金云母和不相容元素的交代富集型地幔源,并具有壳源的元素组成特征。火山岩的形成是富集地幔部分熔融的结果,但在成岩过程中可能存在单斜辉石、斜长石、橄榄石和Ti—Fe氧化物等矿物的分离结晶作用,以及橄榄石的堆晶作用。
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雪鸡坪斑岩铜矿位于西南三江构造火成岩带义敦岛孤带,其成矿斑岩为印支期石英闪长玢岩和石英二长宽岩。研究对该矿区安山岩、矿化斑岩和矿石矿物系统进行S,Pb同位素分析结果表明:金属硫化物的δ34S值为-3.1‰~+0.7‰,平均值为-1.1‰,与矿化斑岩的硫同位素组成(-1.4‰和-1.5‰)一致,均落入幔源硫范围,表明硫主要来自岩浆;δ34S黄铁矿(-1.8‰~+0.7‰,平均0.5‰)〉δ34S黄铜矿(-2.2‰~0.0‰,平均-1.2‰)〉δ34S方铅矿(-3.1‰~1.3‰,平均-2.4‰),硫同位素分馏基本达到平衡。矿石矿物(208Pb/204Pb=37.917~38.230,平均值38.075;207Pb/204Pb-15.528~15.614,平均值15.571;206Pb/204Pb=17.929~18.082,平均值17.981)与矿化斑岩(208Pb/204Pb=37.832、37.883,207Pb/204Pb=15.529、15.538,206Pb/204Pb=17.906、17.910)以及安山岩(208Pb/204Pb=37.816~37.884,207Pb/204Pb-15.549~15.562,206Pb/204Pb=17.845~17.919)的初始铅组成基本一致,变化范围较小,表明三者具有相同的来源;在铅构造模式图上,所有样品铅同位素均位于造山带演化线上或附近,在铅同位素源区判别图中,均落入造山带和下地壳区域,这表明Pb主要来源于壳幔混合。雪鸡坪铜矿S,Pb同位素组成共同指示成矿物质主要来自于深部岩浆,这种岩浆可能主要起源于俯冲洋壳板片的部分熔融并受到少量地壳物质的混染。
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:本文对含金石英脉中流体包裹体进行了研究,结果表明主阶段石英中流体包裹体均一温度为122~306℃ ,存在两个区间分别为130~22O℃、250~270℃ ,均一温度在水平和垂直方向存在规律性变化,盐度主要集中在3% ~8%NaCl范围内,密度为0 80~0.95 c ,流体包裹体具有相对稳定的气液比,流体包裹体气液相成分与典型的岩浆水和大气降水不同。结合氢氧锶和稀有气体同位素研究,认为墨江金矿成矿流体曾发生过部分地幔流体、大气降水等多种类型水不充分的混合,水岩反应和多种流体混合可能为墨江金矿矿质迁移沉淀主要机制。结 合哀牢山金矿带成矿流体类似性和流体包裹体特征分析认为墨江金矿深部可能存在有含金石英脉型矿体。
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To study the relationship between mental-physical health and coping behavior,job stress and job motivation in medical laboratory scientists and technicians. A cross-section survey was conducted,using the anxiety rating scale(SAS), depression rating scale(SDS), coping behavior rating scale,self-rating subhealth scale,self-rating stress scale,and self-rating job motivation scale among 289 medical laboratory scientists and technicians with analysis of ANOVA and Regression. The study was carried out in three steps:step1 is to analyze the general situation of the mental-physical health.Step 2 is to analyze the features of the main influencial facotors.Step 3 is to study the influence of the relative factors on mental-physical health.The following are the results: 1.The anxiety and depression scores of the medical researchers and technicians were 30±6 and 37±8 respectively,both significantly lower than those of the national norm(34±6 and 42±11 respectively,both P<0.01),which are of significant difference. The depression score of the associate chief technician was 42±7, significantly higher than those of the medical researchers and technicians with any other professional titles (all P<0.05), and the anxiety score of the associate chief technicians was 32±7, significantly higher than that of the research fellows(28±4, P<0.05),with no significant difference to the score of the medical researchers and technicians with other professional titles. The depression score,anxiety score and the subhealth score of the age group of 36~49 were 39±9,31±7 and 32±9 respectively, both higher than that of the age group of 20~35 (36±8,29±6 and 29±7 respectively,both P<0.05),while there is much diference among other age groups. And the subhealth status has nothing to do with marital status,education background and professional titles. 2.The coping behaviors,job stress and motivation of the military medical laboratory scientists and technicians. 1)Coping behaviors:The seeking help score of the associate chief technicians was 2.8±0.5,not significantly different from that of the associate research fellows(2.8±0.5),but significantly lower than those of the medical researchers and technicians with other professional titles(all P<0.01),and whose self-blame score was higher than that of the research fellows,which is of significant difference.The self-blame score and the imagination score of the associate research fellows were 2.0±0.5 and 2.4±0.5 respectively, significantly higher than that of the research fellows(1.6±0.4, 2.1±0.4,both P<0.01). The seeking help score of the females was 3.1±0.5, significantly higher than that of the males(2.9±0.5, both P<0.01),and the solving problem score was 3.4±0.6,significantly lower than the male(3.6±0.7, both P<0.01).There is no any significant difference in coping behaviors among researchers and technicians of different marital status,education background and age groups. 2)Job stress: The score of job stress of the age group of 35~49 and 50~60 were 23±8 and 25±6 respectively,significantly higher than that of the 20~35(21±7,both P<0.05). There is no any significant difference in job stress among researchers and technicians of different marital status,gender,professional titles and education background. 3)The score of meeting personal desire for reputation and interests of the males was 19.6±5.4,significantly higher than that of the females(18.4±5.0, both P<0.05), while there is no significant difference in job motivation among researchers and technicians of different titles,education,age and marital status. 3.The relationship of the mental-physical health of the military medical laboratory scientists and technicians with their coping behaviors,job stress and motivations 1) Coping behaviors:Regression analysis showed that, the best predictors of subhealth were anxiety,depression and escaping (β=-0.40,β=0.23, β=0.14, both P<0.01).the best predictors of anxiety and depression were active coping behaviors and negative coping behaviors (β=-0.40,β=0.40, both P<0.01).The moderate(rational) coping behaviors is the best predictor only of anxiety and of significant difference. 2)job stress : Regression analysis demonstrated that anxiety,depression,job stress 2 and job stress 4 are the best predictor for subhealth;job stress 12 is the best retro-predictor for depression; job stress 3 and 8 are the best predictor for depression;and job stress 2 and 9 are the best predictor for anxiety ,which are of significant difference. 3)Motivation:Regression analysis demonstrated that depression is the best predictor for subhealth while motivation itself doesn't predict subhealth;with respect to the specific contents of motivation,"probing unknown rules and making contributions to the human society "is the best retro-predictor for depression and has nothing to do with anxiety prediction. 4) The combined influences of coping behaviors,job stress and motivations: Regression analysis showed that, the best predictors for subhealth were anxiety,depression and job stress(β=0.41,β=0.24, β=0.19, both P<0.01).the best predictors for anxiety and depression were active coping behaviors and negative coping behaviors (β=-0.40,β=0.40, both P<0.01).The moderate(rational) coping behaviors is the best predictor only for anxiety and of significant difference. CONCLUSIONS: Regression analysis showed that the best predictors for anxiety and depression were active coping behaviors and negative coping behaviors, the best predictors for subhealth were anxiety,depression and job stress.Coping behaviors, job stress and motivations have significant influences on the mental-physical health of the military medical researchers and and technicians. Among them,coping behavior is the most important factor while job stress and motivation follow. Seeking help more often,less self-blame ,imagination and job stress could help release the anxiety, depression and improve the subhealth of the medical researchers and technicians. The findings of this study indicate we should address the physical and mental health of the military laboratory researchers and technicians.