膨胀机振动监测与隐患排查研究

通过对膨胀机振动监测信息的研究,及时发现故障苗子,排除仪表监测参数正常的假象,果断进行停机解体检查。通过隐患排查及原因分析研究,验证了振动监测结果,及时修复了轴向推力平衡系统,防止了膨胀机重大损毁事故的发生。以具体实例展示了振动监测系统在了解设备运行状况过程中的重要性。振动监测信息有助于从宏观和微观上了解设备,有助于更科学地制订维修策略和维修计划,既保证设备安全可靠的运行,也确保设备维修的经济性。     

Stability of caisson-type breakwater foundation under tsunami-induced seepage

A tsunami-induced difference between the water levels of the seaward and the landward sides of breakwaters generates one-way seepage in the rubble foundation under the breakwaters. Such seepage may decrease the bearing capacity of the rubble foundation, trigger the piping and/or boiling of the foundation, and cause the scouring of the sandy seabed. In this paper, we describe the stability of a breakwater foundation under the action of seepage based on the results of model tests and FEM analyses. The main feature of our study is the application of the centrifuge technique to such composite hydrodynamic and geotechnical problems. The centrifuge technique can be used to produce high-water pressure and ground stress corresponding to those of prototype-scale breakwaters. The experimental results show that seepage-induced scouring and boiling occur, and that the seepage force decreases the bearing capacity of the rubble foundation. The results of the numerical analyses also reveal the effect of the reduction in bearing capacity in the presence of seepage.     

Design approach to a method for reinforcing existing caisson foundations using steel pipe sheet piles

This paper proposes a steel pipe sheet pile (SPSP) reinforcement method for existing caisson foundations in water. The technique involves driving SPSPs around the caisson foundation and connecting them to it with reinforcing footing. To support the rational design of reinforcements using this method, the following factors influencing the technique׳s effectiveness and related mechanical behavior should be considered: (1) the conditions of the caisson/SPSP reinforcement footing connection; (2) the caisson/SPSP flexural rigidity ratio; (3) the distance between the caisson and the SPSP wall; and (4) the pile length. However, as the influence of these factors on the reinforcement effect and mechanical behavior has not yet been clarified, the current method has no standardization for the concept of the load transfer mechanism in reinforced foundation systems, and the ultimate lateral bearing capacity of existing caissons has been largely ignored in previous construction. This paper describes centrifuge model tests and three-dimensional elasto-plastic finite element total stress analysis conducted in relation to real cases in order to identify a more effective and rational reinforcement structure. The static lateral bearing capacity and seismic performance of reinforced foundations were investigated, and the following factors were considered: (1) the conditions of the caisson/SPSP reinforcement footing connection; (2) the caisson/SPSP flexural rigidity ratio; and (3) the pile length. Finally, a structural design flow is proposed based on the experimental and numerical simulation results. A chart to facilitate determination of appropriate reinforcement structures is also presented.     

石灰改性膨胀土强度的室内试验研究

研究了不同含水率、石灰掺量、干密度、龄期对改性中膨胀土承载力(CBR)值和无侧限抗压强度值的影响。结果表明:不同条件对CBR值和无侧限抗压强度值的影响基本相同;CBR值和无侧限抗压强度值随着石灰掺量、干密度、龄期的增加而增加;最佳石灰掺量为6%;最佳龄期控制在14 d;现场干密度控制在最大干密度;压实含水率按高于最优含水率的2%~3%来控制。     

旁压试验曲线分析及其深度变化特征

松塔水电站1#～6#钻孔旁压试验曲线表明,其压密阶段变化特征直接反映试验成败及试验结果的可靠性,其线性变形阶段与破坏阶段变化特征直接影响地层工程力学参数的取值。通过对7#～9#三个钻孔内的旁压试验结果分析得知,同一土层的旁压试验结果在深度方向上具有大体一致的变化特征,但不同深度其变化曲线不同,对试验结果进行汇总分析,可以对岩土层在深度上的力学特性进行估算,为确定不同深度地基承载力提供帮助。     

Barium Salts of Tetrazole Derivatives – Synthesis and Characterization

The compounds barium tetrazolate ( 6 ), barium 5‐aminotetrazolate tetrahydrate ( 7 ), barium 5‐nitriminotetrazolate dihydrate ( 8 ), barium bis(1H‐5‐nitriminotetrazolate) tetrahydrate ( 9 ), barium 1‐methyl‐5‐nitriminotetrazolate monohydrate ( 10 ), and barium 2‐methyl‐5‐nitriminotetrazolate dihydrate ( 11 ) were synthesized by the reactions of barium hydroxide octahydrate and 1H‐tetrazole ( 1 ), 5‐aminotetrazole ( 2 ), 1,4H‐5‐nitriminotetrazole ( 3 ), 1‐methyl‐5‐nitriminotetrazole ( 4 ), and 2‐methyl‐5‐nitraminotetrazole ( 5 ), respectively. The compounds were characterized using multi‐nuclear NMR spectroscopy, vibrational (IR and Raman) spectroscopy, elemental analysis, and differential scanning calorimetry. The solid‐state structures of 7 – 11 were determined using low temperature X‐ray diffraction and a comprehensive characterization is given. In addition, the sensitivities (impact, friction, electrical discharge) of 6 – 11 were investigated and bomb calorimetric measurements were carried out.     

The Development of a New Synthesis Process for 3,3′‐Diamino‐4,4′‐azoxyfurazan (DAAF)

Process optimization studies were performed for the preparation of the high explosive 3,3′‐diamino‐4,4′‐azoxyfurazan (DAAF). These process studies were pursued to address issues such as problematic waste generation products, particle size, impurities, and manufacturability. This paper describes the original synthesis method and inherent issues. An optimization process was designed to investigate the issues with purity and manufacturability. Particle size effects were addressed by adding a recrystallization step to the synthesis. Ultimately, a complete solution to all observed issues was found with a new synthesis process, which now allows DAAF to be prepared without any impurities, with good particle size and without the need for recrystallization. Importantly, the new synthesis process can be performed in an environmentally friendly manner, with the production of non‐hazardous waste.     

石蜡相变微胶囊研究进展

介绍了石蜡相变材料物相变化的特点,阐述了石蜡微胶囊制备的主要方法。对石蜡微胶囊在能量利用与热交换、温度控制和军事领域的应用进行了综述。分析了石蜡微胶囊在研究和应用中存在的问题及解决的方向。     

EVA/ATO透明隔热中间膜的制备及性能研究

通过挤出共混法将透明且具有红外反射功能的纳米锑掺杂二氧化锡(ATO)添加到乙烯-乙酸乙烯酯共聚物(EVA)中,并经热压成型制备了夹层玻璃用EVA/ATO透明隔热中间膜;表征了EVA/ATO中间膜的隔热性能,并考察了ATO用量对EVA/ATO材料的拉伸性能、光学性能、热稳定性及其与玻璃的黏合性能的影响。结果表明,添加1%～5%(质量分数)纳米ATO的EVA/ATO胶膜对光的透过性能表现出明显的光谱选择性,能在保持相对较高的可见光透过率的同时,有效地阻隔红外光区的热能;随纳米ATO用量的增加,EVA/ATO材料的隔热效果不断提高,但其热导率也呈上升趋势。与未添加ATO的EVA相比,用EVA/ATO(ATO质量分数为3%)中间膜制作的盖板能够使隔热箱内的空气温度降低7.9℃。在所考察的ATO用量范围内,所制备的EVA/ATO透明隔热中间膜与玻璃的强度均大于3000N/m。     

Active metal-based corrosion protective coating systems for aircraft requiring no-chromate pretreatment

There has been much R&D effort expended to develop pretreatments and coatings that allow the replacement of toxic, carcinogenic, mutagenic, environmentally hazardous chromates used as pretreatments and pigments in aircraft coating systems. There have been many claims for chromate replacement in primer and pretreatment systems for aircraft, but no systems presently are in use that can function and meet specifications without some form of chromate used in the pretreatment and/or primer. The Mg-rich primer technology developed at North Dakota State University and now in final commercial development at AKZO Nobel Aerospace Coatings shows that finally aerospace Al alloys can be protected against corrosion. With simple cleaning only or a non-chromate pretreatment, the Mg-rich primer (MgRP) + aerospace topcoat provides an aircraft protection system that give corrosion protection that equals or exceeds any system using chromate in any form. About 18 peer reviewed papers have been published and at least twice that many presentations at technical meetings describing this new aircraft primer technology. There are an extensive number of samples in outdoor exposure, and in exposure on small parts of aircraft like port-hole covers and doors, and the coating system has been in accelerated exposure cabinets of all sorts. In the first versions of the magnesium primer premature blistering was noted during immersion or B117 continuous salt spray testing which may be due to hydrogen generation from water contact at a particle. Efforts to control the level of activity of the magnesium have been successfully accomplished since the testing reported in this paper which controls this phenomenon. Current formulations meet and exceed the ASTM B117 test results of full chromate primer systems. Open circuit potential (OCP) measurements indicate an extended period of cathodic protection of the Al aircraft alloys such as AA 2024 T-3 and AA 7075 T-6. After this stage of protection, a combination of Mg oxide, hydroxide and carbonate compounds seem to give protection to the system, as we have seen corrosion protection given to samples for greater than 10,000 h of cyclic exposure for Mg-rich primers with good aerospace topcoats. Preliminary data are presented for other Mg alloys as pigments in metal-rich coating systems. All data indicates that the Mg-rich (or Mg-alloy pigment-rich) primer + aircraft topcoat system gives excellent corrosion protection by mechanisms entirely different from the modes of protection for aircraft alloys given by the toxic, carcinogenic chromate compounds now in use in all corrosion protection systems for aircraft. In most cases thus far examined, the protection, especially in cyclic exposure, exceeds the present chromate-based systems.