The role of microstructure on pesting during oxidation of MoSi2 and Mo(Si,Al)2 at 773 K

The pesting behavior of MoSi₂ and Mo(Si,Al)₂ has been examined in air at 773 K to clarify the origin and mechanism of pesting phenomena and the effect of aluminum on pesting phenomena. The initial cracks play a much more important role than the grain boundaries and the initial oxide layer in pesting. Mo and Si oxidize to amorphous Mo-Si-O simultaneously with about a 200% volume expansion. Therefore, large stress appears at the cracktips and induce many new cracks. MoO₃ vaporizes from the Mo-Si-O layer on the external surface and crack surfaces causing the oxides in the initial cracks to become porous. Oxygen has a short-circuit path to enter the sample in the cracks. Therefore, the partial pressure of oxygen is sufficiently high to allow oxidation of Mo in the materials. The platelet-like MoO₃ grows on the external surface and also in the cracks. Finally, the sample distintegrates into powder. Pesting of Mo(Si,Al)₂ occurs in the same way, however, its rate is much lower than that of MoSi₂. The role of Al is to decrease the initial crack density of the samples from the melt. Other effects of Al might be to decrease the oxygen flux toward the oxide-intermetallic interface and to increase the plasticity of the amorphous oxide being formed in the cracks.     

Ultrasonic pre‐treatment of biological sludge: consequences for disintegration,anaerobic biodegradability,and filterability

BACKGROUND: Disintegration was developed as a pretreatment process for sludge to accelerate the digestion processes. Ultrasonic treatment may be a good alternative for sludge disintegration. In this study, different specific energy inputs ranged between 0 and 15 880 kJ kg^?1 and very low ultrasonic densities ranged between 0.04 and 0.1 W mL^?1 were applied to biological sludge for disintegration purposes. The potential for improving anaerobic digestion through ultrasonic pre‐treatment and the effect of ultrasonic pre‐treatment on the filterability characteristics of sludge were also investigated. RESULTS: 9690 kJ kg^?1 TS of supplied energy and very low power density of 0.09 Wm L^?1 are efficient for floc disintegration. For 9690 kJ kg^?1 TS, 44% higher methane production was achieved than with raw sludge as a result of biochemical methane potential assay. The supernatant characteristics of the sludge were also affected by the ultrasonic pre‐treatment. For 9690 kJ kg^?1 TS, the soluble chemical oxygen demand (SCOD), dissolved organic carbon (DOC), total nitrogen (TN), and total phosphorus (TP) in the sludge supernatant increased by 340%, 860%, 716%, and 207.5%, respectively. CONCLUSION: Ultrasonic pre‐treatment is an effective method for biological sludge disintegration even at very low ultrasonic density levels. It leads to increased anaerobic biodegradability but deteriorates the filterability characteristics of biological sludge. Copyright © 2009 Society of Chemical Industry     

异常高压气井生产动态仿真研究及应用

异常高压气井生产动态仿真方法不仅改变了传统物理仿真成本高、过程复杂的缺点,而且具备了计算机仿真模拟的准确性。考虑异常高压气井流体高压、高温的特点,本文将异常高压气井生产压降分解为地层流动压降、井筒流动压降和嘴流流动压降三个过程,并建立了气井生产动态流动数学模型;本文利用计算机仿真技术模拟了异常高压气井地层流体流动过程、井筒流体流动过程和气嘴流体流动过程,并预测了气井生产动态流动参数,为下步异常高压气井动态配产提供了基础数据。通过实例分析,将计算机仿真预测出的异常高压气井流动参数代入优化配产模型计算出配产结果与实际配产结果十分接近,表明异常高压气井生产动态仿真对实际生产具有重要的指导意义。     

高铝锌合金离心铸件带状缩松的形成机理

介绍了高铝锌合金离心铸件带状缩松的形态特征，并对其形成机理进行了分析。     

水平井分层试油管柱及工艺

介绍了套管完井方式的水平井对分层试油工艺管柱的要求、管柱结构、工作原理；介绍了替喷、气举和泵抽等分层试油工艺方法。用该管柱在埕科一井、水平一井两口水平井上对６个层位进行了１１井次的分层试油，取得了齐全准确的油水性及压力等试油资料，通过对试油资料的分析知道工艺管柱的工作效果良好，封隔器密封可靠。实践证明：对于地质结构特殊的油藏可以打水平井穿透多个油层，进行分层试油和开采；水平井分层试油工艺管柱应采用液压操纵和控制，常规试油工艺可以用于水平井；水平井中油管重力对封隔器密封的影响可忽略不计。     

ZHS添加剂对济(源)钢烧结矿性能的影响

通过对济源钢铁公司烧结矿添加ZHS添加剂的系列试验，着重研究了ZHS添加剂对烧结矿转鼓指数，还原性，低温还原粉化率及熔滴性能的影响，试验表明，ZHS添加剂对改善烧结矿冶金性能具有良好效果，为改善济（源）钢烧结矿质量提供了新的途径。     

Zonal network solution of temperature profiles in a ventilated wall module

A ventilated wall module is an outdoor air-intake device that can clean the drawn air, reduce heat loss or gain, and insulate outdoor noises. It contains a solar board, air cavities, and an air filter. This investigation proposes a zonal network model to efficiently predict temperature profiles in a ventilated wall module. The thermal network is established by applying an energy balance to each network node. The outdoor temperature, indoor temperature, and solar irradiation intensity are specified as boundary parameters. The proposed model is validated by the measured temperatures in a prototype model. The results show that the proposed model provides reasonably accurate temperatures with a maximum gap of 3°C between the prediction and the measurement. The temperature profiles approach straight lines when the mass flow rate significantly increases. A similar trend is observed when the solar irradiation intensity, the solar board absorptivity, or the glass transmitivity dramatically decreases.     

排风隔热窗一维简化传热模型研究

排风隔热窗作为一种新型外窗结构,可以有效地降低室内侧玻璃表面与室内空气之间的温差,减少外窗形成的室内负荷,改善室内的热舒适性。利用能量守恒原理,建立了排风隔热窗的一维简化传热数学模型,研究了该结构外窗在夏热冬冷气候条件下的传热特性。将排风隔热窗的简化传热数学模型和区域模型的计算结果进行比较,计算结果表明,简化模型可以较好地模拟排风隔热窗的传热特性,适用于研究初期的简化计算和工程计算。     

苯磺酸氨氯地平口腔崩解片处方优化的研究

目的研究苯磺酸氨氯地平口腔崩解片处方的优化。方法结合矫味剂和β-环糊精包合技术改善口感,通过正交实验筛选最优处方。结果最优处方为:苯磺酸氨氯地平0.3g,β-环糊精1.0g,阿司帕坦0.05g,枸橼酸0.25g,微晶纤维素2.5g,α-乳糖1.35g,甘露醇0.5g,硬脂酸镁0.1g。产品崩解时限为(12.10±0.06)s。结论所得产品能较好地达到口腔崩解片的各项要求。     

Numerical simulation on the behavior of a liquid jet into an air flow

A numerical simulation has been performed to clarify the effects of turbulence in a liquid on the deformation of the liquid jet surface into an air flow. The turbulences in the liquid jet were simulated by the Rankin vortices, and the liquid jet surface was tracked numerically by the volume of fluid method. By numerical simulations, the onset of the protrusions on the liquid jet surface is caused by the vortices in the liquid, and the surrounding air flow plays an important role in the amplification of the protrusions. The amplification rate of the trough displacement is proportional to the air‐to‐liquid velocity ratio. At large imposed vortex intensities, the trough displacement increases with the vortex intensity. On the other hand, at small imposed vortex intensities, the amplification of the trough displacement is also affected by factors other than vortex intensity. © 2001 Scripta Technica, Heat Trans Asian Res, 30(6): 473–484, 2001