多弧离子镀铝工艺对TC4钛合金微弧氧化膜结构及性能的影响

采用多弧离子镀技术,在不同偏压和沉积温度工艺条件下,在TC4钛合金上制备铝镀层,然后进行微弧氧化。采用光学显微镜、摩擦磨损试验机、点滴试验研究了不同多弧离子镀工艺对镀铝层微弧氧化磨微观结构、耐磨性和耐蚀性能的影响。结果表明:随着多弧离子镀基体偏压由-200 V增加至-300 V,温度由25℃增加至250℃,微弧氧化膜表面变得更致密,膜层表面微孔孔径减小,偏压和温度分别为-300 V、250℃的条件下,微弧氧化膜的摩擦系数最低,磨损量最小,在酸性重铬酸钾溶液的点滴实验中,耐蚀性最好。     

煤低温氧化的红外光谱研究

利用傅立叶红外光谱(FTIR)分析了下沟煤矿8#煤层煤样经过不同温度、不同时间氧化的产物中,各官能团的组成及变化,研究了煤中部分官能团随氧化温度和时间变化的规律,据此推测了煤低温氧化的反应历程。     

姚桥煤矿8煤低温氧化的研究

不同温度下煤氧化的吸氧量和放热量是进行煤自燃数值模拟的基础数据,氧化放热量的测定直接影响到模拟的基础数据,氧化放热量的测定直接影响到模拟结果是否符合实际。通过对姚桥煤矿8煤在不同粒度和水分条件下吸氧量和放热量随温度的变化规律,分析8煤低温氧化的规律性。     

钢件氧化工艺的影响因素分析

在工业生产中,经碱性氧化(发黑或发蓝)处理的钢铁件,易出现挂红,氧化膜疏松,氧化膜色泽不均匀以及经过后处理的钢铁件表面泛白斑,易锈蚀等问题,严重影响氧化膜质量.本文巧妙地采用了近似“稳态”反应条件,通过单因素实验探讨氧化液的组分、氧化时间以及操作工艺等多因素对氧化效果的影响,针对性地对上述故障进行初步分析,并提出一些改进方法.     

谈煤的孔隙大小分类

介绍了目前常见的测试煤孔隙的方法及分类方案,并在此基础上提出了建议使用的煤孔隙大小的分类方案。     

两种山野菜与蔬菜中矿物质含量的比较研究

目的:对山野菜和蔬菜中矿物质含量进行分析和比较,为野菜的综合开发利用提供理论依据。方法:取荠菜、蒲公英、芹菜和韭菜的可食部位作为样本。用原子吸收分光光度计测定其钙、铁、锌含量。结果:每100g荠菜含铁3.20mg;锌0.28mg。100g蒲公英含钙98.34mg;铁3.85mg;锌0.16mg。100g芹菜含钙107.40mg;铁2.45mg;锌0.14mg。100g韭菜含钙59.75mg;铁2.67mg;锌0.28mg。结论:荠菜钙的含量高于蒲公英及蔬菜。野菜中的铁和锌元素高于蔬菜。     

吉伦台-塘坝4勘查区八道湾组三段含煤性与煤质特征

新疆尼勒克煤田吉伦台-塘坝4勘查区位于天山褶皱带西部,具山间盆地特征。文章通过煤岩特征与含煤性、煤层与空间展布、煤质特征、煤质类型与风氧化特征等分析,阐述了八道湾组三段含煤性与煤质变化特征。     

谈化工氧化过程的基本原理

化工氧化过程分为均相催化氧化过程和非均相催化氧化过程。均相催化氧化反应有多种类型,工业上常用催化自氧化和配位催化氧化两类反应。配位催化氧化反应中,催化剂由中心金属离子与配位体构成。将对化工氧化过程的基本原理进行详细阐述。     

高活性氧化钙生产技术

1技术原理高活性氧化钙的生产技术，系选用优质石灰石（主要成分碳酸钙）和煤，在普通生产石灰工艺基础上，加入激发素和除硫团化剂，经高温级烧而得。以氯化钠作为激发素，在浴烧过程中，由于氯化钠的事与作用，增加了碳酸钙的分解速度和氧化钙的结晶速度，确保氧化钙由细小晶粒组成的疏松块状集合作。同时，选用石灰、三氧化二铁、二氧化标、硝酸钠等组成的除硫团化剂添加在煤中，促使煤中的一氧化碳和二氧化硫发生放热氧化反应，最后形成馆点较高、较难分解的化合物沉积在炉渣中，因硫率达到70％～80％以上，既能充分发掘和利用煤的热效…     

浅析煤炭自燃中水分的影响因素

水分对煤的低温氧化的作用是双重的,即水分对煤的低温氧化或是促进作用或是抑制作用。通过查阅文献,对水分两种作用的原因进行解释：水分对煤的低温氧化究竟是哪种作用取决于煤中的水分含量,并存在一个最佳的水分含量使得煤的低温氧化过程最容易进行;不同煤种这个最佳水分含量是不同的,褐煤大约为25％。30％,无烟煤大约为25％,烟煤则根据其具体煤种分类的不同,最佳水分含量也不相同。     

The impact of numerical superstition on the final digit of stock price

This paper investigates the extent to which the frequency distribution of the rightmost digit of stock prices is influenced by numerical superstitions. To identify the moderating variables that strengthen the superstition for numbers, we take into account factors including the amount of information, change of tick size, Chinese festivals, and bear market effect. Furthermore, we examine whether the frequency of lucky (unlucky) numbers as the final digit of prices decreases (increases) for firms with higher trading by institutional investors. The results indicate that investors in the Taiwan Stock Exchange tend to avoid number 4. Our results also find that the effects of numerical superstitions on the frequency of the final digit decrease when the amount of information increases. Investors appear to be more likely to avoid unlucky number 4 in the following four conditions: when the tick size becomes smaller, when it is one week before Chinese New Year, when it is the seventh month in the lunar calendar, and when it is in a bear market. We further document that institutional investors are not affected by numerical superstition. Moreover, our results support the notion that informed traders buy and sell more (less) actively the stocks with a lower (higher) frequency of prices ending with 4.     

吉伦台-塘坝矿区7井田煤质特征及其变化规律探讨

通过对勘查区地质资料和煤质化验成果分析,阐述了煤质基本特征,初步分析认为本区的煤层由浅入深随着煤层埋深增加,变质程度也逐步增大的希尔特定律。煤类变化规律是:在地质剖面上呈现垂直分带现象,上部煤层较下部煤层变质程度低;在水平分带上,同一煤层中北部较南部变质程度高。从煤类分带图上可以看出,本区主要煤类有长焰煤(41CY、42CY)、不粘煤(31BN)、气煤(43QM、44QM、45QM)。     

Employers' hiring practices,employment protection,and costly search: A vacancy-level analysis

An employer with a vacancy may respond to high search costs by lowering hiring requirements. While such an adjustment increases the employer's chances of filling the vacancy, it also more likely results in a match that terminates when the match is hit by match-specific productivity shocks. Drawing on a novel Slovenian vacancy dataset, we find that employers who are searching to fill temporary positions are more likely to hire underqualified workers when search costs are high. We find that search costs are taken into consideration when employers are searching to fill permanent positions in some specifications but not all. These findings suggest that for employers who are searching to fill a permanent position, the benefits of lowering hiring requirements when search costs are high are likely outweighed by: a) high firing costs if an under-qualified worker is hired on a permanent contract or b) the costs of undertaking a new search later if an under-qualified worker is hired on a temporary contract. These are novel findings about the employers' hiring practices in the presence of employment protection laws and costly search.     

基于矿区水文地质条件及含水层分布特征分析

本文对七台河东部某矿区进行了水文地质条件综合分析。就含水层和隔水层的分布,对第四系裂隙含水带,风化裂隙含水带,亚风化孔隙含水带,立新河第四系孔隙含水层,侏罗系含煤地层裂隙含水层,含水性较强的岩层,含水性中等岩层,含水性较弱的岩层等进行了规律与特征分析。     

煤矿经济形势分析

经济的发展增加了对煤炭的使用量,有越来越多的煤炭企业开始更多的进行煤炭采挖。煤炭是不可再生的,需要企业对其进行有效管理和利用。本文通过对我国煤炭经济的发展形势进行分析,提出了相关的发展策略。     

复杂地质条件下的煤矿掘进支护技术应用探究

近年来,我国煤矿开采的强度不断增加,开采范围和深度持续增大,使得煤矿开采的地质条件越来越复杂。本文就复杂地质条件下煤矿掘进支护技术的应用进行分析探究。     

多孔结构建筑材料力学性能的有限元分析

多孔材料是一种新兴的材料,制备较易,成本较低。相对于一般连续介质材料而言,多孔材料具有比强度高、比表面积高、相对密度低、重量轻、隔音、隔热等优点。它最大的特点是具有排列规则、大小可调的孔道结构,在建筑材料中也有很多的应用。因此,对非均匀孔洞与均匀孔洞建筑材料力学性能的研究是很重要的课题。论文通过建立非均匀孔洞和均匀孔洞的有限元模型,对比分析两种模型的受力性能,更好地进行多孔建筑材料的推广和使用。     

Economic Background to the Coal Dispute

This Briefing Paper attempts to explain the economic forces behind the decline of the coal industry. The main findings (presented in the order in which the argument is developed) are:

• 1 Coal output has been declining throughout this century. This decline accelerated in the 1950s and 1960s when coal was faced with competition from oil.
• 2 The decline was arrested by the the oil price increases of the 1970s which have allowed coal to establish and maintain a price advantage over alternative fuels. Despite this, coal has not increased its market share over the past decade.
• 3 Because of energy conservation, in response to the price increases of the 1970s, total energy demand has fallen over the past ten years.
• 4 With coal holding a stable share of a static market, the output projections for the industry drawn up in the 1970s including those in the 1974 “Plan for Coal” are now totally outdated.
• 5 Even if total energy demand were to expand, there would not necessarily be increased demand for British coal, which is more expensive to produce at the margin than alternative sources of supply (from the US, South Africa and Australia).
• 6 Home-produced coal enjoys some natural protection from overseas competition because of high transport costs. In addition there is a tax on fuel oil and informal restrictions on imports. These partially insulate the domestic price of coal from changes in the world price.
• 7 The cost of producing coal has risen substantially in real terms since 1973-4, despite a major investment programme. Productivity has risen slightly faster than the national average, but wages and non-wage costs have risen very much faster.
• 8 The upward pressure on costs has come partly from the mineworkers' climb from twelfth to first or second place in the wages' league; and partly from the failure to close non-economic pits fast enough.
• 9 This pressure on costs meant that by 1981-2 less than half of the industry's total output was produced at profitable pits, which employed only 65,000 mineworkers.
• 10 There is a large tranche of marginally uneconomic pits which may be unprofitable one year but profitable another, and there is a strong case for keeping such pits open.
• 11 The number of pits which are profitable at the margin is very sensitive to movements in costs. I f mineworkers' wages had risen only in line with the national average for manufacturing over the period 1973-4 to 1981-2, the number of jobs in profitable pits would have been 95,000 rather than 65,000.
• 12 The subsidy per man in the most inefficient pit in 1981-2 was of the order of £14000. The subsidy per man in the marginal pit at break-even point for the industry as a whole was nearly £5000.
• 13 Under a cash limit system every pound spent on subsidising miners is a pound less available to spend elsewhere. Subsidising coal miners is a costly way of preserving jobs compared with alternatives.

     

居民收入增长对城市生活废弃物产出量的影响

近年来,随居民人均收入的增长,国内城市生活废弃物问题呈现出持续恶化的态势.从微观个体的角度对其进行分析,可以将问题产生的诱因归结为收入效应和替代效应:收入效应,收入增长使消费者可以购买更多的商品,这造成生活废弃物的增加;替代效应,收入上升使消费者消费商品的时间机会成本也随之上升,为节约时间机会成本,消费者倾向于购买更多的一次性商品,这导致生成更多的生活废弃物.通过提高城市居民的环保意识来增加其消费产品的边际负效用,是缓解城市生活废弃物问题持续恶化的有效途径.