铝箔纸替代金属环进行建筑密封材料质量损失率测试的可行性探讨

分别参照国标GB/T 13477.19—2017《建筑密封材料试验方法第19部分:质量与体积变化的测定》规定的金属环法和企业简易铝箔纸法对市场上40种建筑用硅酮耐候密封胶进行质量损失率测试,对两种方法试验结果进行了比对分析,探讨两种测试方法间数据的关联性以及铝箔纸法替代金属环法的可行性。

建筑密封胶密度试验方法的研究

介绍了建筑密封胶密度试验方法的研究背景,对金属环法、金属模框法及体积校正法3种密封胶的密度测定方法进行了研究分析。结果表明,采用金属环法和金属模框法测定密度能有效降低体积校正法中体积标定引起的误差,弥补试样体积校正程序,提高试验结果的重现性,使试验结果更加准确、合理。同时,金属环法和金属模框法测定密度适用范围更广、方法更严谨。

Persistent toxic substances in urban highway runoff in Shanghai

Urban highway runoff samples from seventeen rainfall events were collected in Shanghai in 2011. The concentrations of ten heavy metals and sixteen polycyclic aromatic hydrocarbons PAHs are analyzed. The results show that the heavy metal concentrations range within 0.50 to 51.80 As 0 to 20.80 Se 13.67 to 445.80 Zn 0 to 44.20 Pb 0 to 15.80 Ni 39.58 to 264.20 Fe 0 to 253.00 Mn 0 to 8.20 Cr 0 to 124.20 Cu and 159.83 to 536.40 μg/L Al . Se Pb Mn and Al concentrations in most samples exceed their corresponding criterion continuous concentrations CCCs while Zn and Cu concentrations exceed their criterion maximum concentrations CMCs .The concentrations ofΣPAHs range within 37.25 to 114.57 ng/L and concentrations of PAHs are all below their corresponding CCCs.Cu Zn and ΣPAHs show the first flush phenomenon. Analysis results of the modified Nemerow index method NIM indicate that runoff from eight rainfall events may have very strong biological toxicity effects four have strong effects three have moderate effects and only two have insignificant effects.Therefore it is concluded that urban highway runoff is a significant pollution source to aquatic ecosystems and needs immediate purification.

Application of synthetic principal component analysis model to mine area farmland heavy metal pollution assessment

Referring to GB5618-1995 about heavy metal pollution,and using statistical analysis SPSS,the major pollutants of mine area farmland heavy metal pollution were identified by variable clustering analysis.Assessment and classification were done to the mine area farmland heavy metal pollution situation by synthetic principal components analysis (PCA).The results show that variable clustering analysis is efficient to identify the principal components of mine area farmland heavy metal pollution.Sort and clustering were done to the synthetic principal components scores of soil sample,which is given by synthetic principal components analysis.Data structure of soil heavy metal contaminations relationships and pollution level of different soil samples are discovered.The results of mine area farmland heavy metal pollution quality assessed and classified with synthetic component scores reflect the influence of both the major and compound heavy metal pol- lutants.Identification and assessment results of mine area farmland heavy metal pollution can provide reference and guide to propose control measures of mine area farmland heavy metal pollution and focus on the key treatment region.

Effect of surface treatment to inserted ring on Al–Fe bonding layer of aluminium piston with reinforced cast iron ring

In order to improve the bonding strength between piston alloys and cast iron ring of aluminum piston with reinforced cast iron ring,the different methods of the surface treatments(shot blasting and sand blasting) to the cast iron ring are experimented.The optical micrograph shows that an intermetallic layer and a ligulate shaped structure are formed between piston alloys and cast iron base ring.After sand blasting treatment,the ring surface is non-metal shiny,matte-like and has no obvious pits.The intermetallic layer thickness formed between piston alloys and cast iron is thinner and more equally distributed after sand blasting to the ring.The content of the graphite distributed the interfacial zone after the shot blasting treatment is little.With the increase of time by sand blasting,the hardness starts to slightly descend.The bonding strength of the sample by sand blasting is obviously higher than that by shot blasting and increases from 9.32 MPa to 19.53 MPa.

Glass Melting Phenomena of a Fluorescent Lamp and a Protection Method by a Metal Ring

The formation mechanism of the discharge spot at a bottom of a lead wire in a fluorescent lamp at end-of-life is investigated. When the lamp at end-of life is ignited by applying high voltage, glow-like discharge is formed on the surface of the lead wire. A few seconds later, a bright spot is formed at the bottom 0fthe lead-wire. Then the stem glass on which the lead-wires are mounted begins to melt. High electric field is formed between the surface of the lead-wire and the stem glass surrounding the lead wire. Then discharge spot will be formed at the contact portion of the lead wire to the stem glass by this high electric field. To prevent discharge spot formation at the bottom of the lead wire, the metal ring is set to encircle the lead wire and is connected to the lead wire potential through a resistor. By this configuration, discharge spot formation is effectively suppressed. The mechanism for preventing hot discharge spot formation by the metal ring is discussed.

Research on the Progress of Environmental Remediation Methodologies under the Conditions of Oil and Heavy Metal Pollution

In this paper, we conduct research on the progress of environmental remediation methodologies under the conditions of oil and heavy metal pollution. The main repair contaminated soil measures include chemical, physical and chemical measures, biological repair measures and agricultural ecological measures, engineering measures, etc. Selection principle is to adjust measures to local conditions, at the same time, take the technical, economic and effects of factors such as accessibility. After comparing the mentioned techniques, we conclude that the bioremediation method holds the best effectiveness for us to make contribution to the environmental protection. In final part, we give the conclusion and sct up the prospect.

Numerical and experimental analysis of the reusability of spring energized metal C rings

It is well known that static seals are usually designed to be used once. In this paper, we discuss the reusability of a type of static seal called the spring energized metal C ring, which is required to be reused 4-5 times without maintenance during the lifetime of the pump. A theoretical analysis based on the nonlinear finite element method and an experimental investigation of the reusability of the C ring are carried out. The effects of the elastic modulus of the ring material, the ring wall thickness, the amount of assembly interference between the spring and the C ring, the operating temperature and the compression ratio are discussed. The parameter S, which denotes the reaction force difference percentage, is determined to measure the reusability of the C ring. The results show that the ring wall thickness plays an important role in the reusability. Although the normal force of a thick wall decreases after the ring is reused eight times, the value is still higher than the first normal force of a thin wall. In contrast, the elastic modulus of the material has the lowest impact. Here, a pre-compression ratio of 18.2% not only produces a larger first normal force but also leads to a smaller reduction in the normal force when the ring is reused. A simulated experiment is carried out to investigate the influence of the coating of the C ring on its reusability. The results show that when plastic deformation occurs on the contact surface, the contact state of the C ring coating becomes a major factor that affects the seal performance. Aging treatment at high temperatures （250℃） reduces gized metal C ring, which leads to the deterioration in the reusability the binding force of the silver coating on the spring ener of the ring.

Risk Assessment of Metal Contamination in Soil and Groundwater in Asia： A Review of Recent Trends as well as Existing Environmental Laws and Regulations

Asia is experiencing a more rapid economic growth compared to any other regions. The contamination of soil and groundwater with metals can mainly be attributed to human activities; therefore, risk assessments to characterize the nature and magnitude of risks to humans and ecological receptors from contaminants are important. Risk assessments are often iterative processes, which involve identification and filling data gap. Experimental samplings, geostatistical and multivariate statistical methods as well as multimedia risk assessment modeling are the three major methodologies used in the assessment of metal contamination in soil and groundwater.This review highlights a number of measurements for improving risk calculation methods and expounds scientific approaches that involve the identification of the major source of contamination, exposure pathways and bioavailability of metals. In general, risk assessments of metals in soil and groundwater worldwide are mainly focused on the levels of contamination, identification of exposure pathways, and prediction of the probability of contamination. To date, very limited studies have reported the development of relevant environmental laws and policies in the regulation of soil and groundwater contamination in Asia. The development, variations and limitations in the regulations of soil and groundwater contamination among developed countries may provide helpful guidance for the developing countries in Asia.