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海洋立管是海上油气集输系统的重要组成部分,用于连接海底油气井口与海上油气集输站。在油气储运工程中,海洋油气集输介质多为油气水三相流体。为了研究油气水三相流海洋立管系统在严重段塞流作用下产生的耦合振动问题,进行了数值计算与实证研究。基于多相流体力学与动力学理论,构建了油气水三相严重段塞流模型和海洋立管结构动力学模型,结合这2个模型,模拟了立管耦合振动响应过程,并设计了下倾管倾斜角度为3°的L型油气水三相流立管系统进行实验。对模型计算值和实测值进行对比,结果表明:所提出的耦合振动响应模型比现有严重段塞流瞬态数学模型更适用于油气水三相段塞流引起的海洋立管耦合振动响应问题的研究,计算结果与实验结果较吻合;立管底部压强与底部位移呈周期性变化,且变化周期基本一致;流体压强是引发立管系统耦合振动响应问题的关键因素。研究结果为油气水三相流海洋立管系统在严重段塞流作用下的耦合振动响应特性分析及其结构设计提供了参考。 相似文献
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《功能材料》2017,(7)
以超磁致伸缩材料(giant magnetostrictive material,GMM)作为接收端负载的磁耦合谐振式(magnetically coupled resonant,MCR)WPT系统中存在电-磁-机多场耦合问题,由此增加了系统数学和电路建模复杂度。为解决上述问题,分析以GMM为负载的MCR WPT系统,构建其电路模型,采用多场耦合理论分析MCR WPT接收端负载GMM的阻抗特性。由分析结果可知,电磁线圈缠绕下的GMM阻抗特性为感性,其数值由电气部分和机械部分转换后共同组成。基于GMM的电气阻抗模型,对MCR WPT系统接收端模型进行仿真分析,并构建MCR WPT系统进行实验验证,实验结果与建模结果吻合,表明所提出的GMM负载多场耦合建模方法的正确性和有效性。 相似文献
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《高分子材料科学与工程》2015,(5)
以甲氧基聚乙二醇甲基丙烯酸酯(m PEGMA)、甲基丙烯酸-N-N-二乙氨基乙酯(DEAM)为单体,2,2'-二硫二乙醇的二甲基丙烯酸酯(SS)为交联剂,采用自由基交联共聚法制备了具有p H-GSH双敏感性的P(m PEGMA-DEAM-SS)水凝胶。研究了溶剂对凝胶溶胀性能的影响,并初步研究了在不同介质中水凝胶的溶胀动力学。结果表明,以N-N-二甲基甲酰胺(DMF)为溶剂时,可获得良好p H响应能力的水凝胶;水凝胶的溶胀过程表现出良好的p H-GSH双敏感性,该水凝胶的扩散行为在酸性介质中符合non-Fickian模型,而在中性介质则符合Fickian模型;在10 mmol/L GSH条件下,水凝胶溶胀率上升了4倍多,其扩散亦为non-Fickian扩散模式。 相似文献
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本文对应用分相的普适性及定量计算方程来预测分相区进行了分析,认为,对二元系统的分相,只要知道临界点的实验值或临界点附近某两点以上的实验值,就可定量预测出临界点附近的分相区。并用此方法对已知分相区的硼酸盐碱土金属二元系 RO-B_2O_3(R=Mg、Ca、Sr、Ba)的分相区进行了预测验证。结果表明,用本文的方法来预测它们的分相区是可行的。本方法可望用于其它二元系统分相区的预测。 相似文献
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跨介质飞行器气/水两相弹道仿真研究 总被引:1,自引:0,他引:1
《工程力学》2010,(8)
跨介质飞行器是介于空气与水之间运动的新概念两栖飞行器,由于同时受到空气动力,水动力的作用,动力学特征较巡航飞行器和水面滑行艇均有很大差别。基于空气动力学和二元平面滑行理论,建立了跨介质飞行器滑跳动力学模型。重点对飞行器滑跳弹道特点进行了分析,并对滑跳弹道影响因素进行了仿真研究。结果显示:滑跳飞行距离和飞行器推力对滑跳弹道均有较大影响。研究结果可以为跨介质飞行器总体设计,弹道设计与优化和飞行稳定性评估等方面提供了理论依据和研究手段。 相似文献
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This paper presented the fabrication and calibration of a clad-modified evanescent based plastic optical fiber (POF) sensor for the detection of ammonia in both stagnant and dynamic aqueous media. This optochemical sensor was based on Oxazine 170 perchlorate (sensing material) and polydimethylsiloxane (PDMS) (protective material) thin layers. A special chemical solution was developed for the etching removal of cladding and a methodology for trapping moisture was exercised. Experimental results on dissolved ammonia detection exhibited short response time (≤10 s), low detection limit (minimum detection limit 1.4 ppm), high sensitivity, and excellent reversibility (over 99%). 相似文献
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We propose and analyse a novel optical pressure sensor based on series-coupled double microring resonators (SDMRRs) on a simple beam. The pressure applied on the sensor is measured through the change of the optical transmission spectrum at the output port. The optical transmission performances of the SDMRRs have been analysed and compared with the single and paralleled-coupled structures by the method of finite element analysis and numerical simulation. The simulation results showed that the stress sensitivity is 0.0225?kPa–1 and linear measurement range of the sensor is 30?kPa. Furthermore, the influence of the amplitude transmission coefficient, half round phase shift and microring radius on the sensitivity have been investigated to optimize the sensor performance. This proposed sensor can be used for the smaller pressure detection in automotive, aerospace, oil/logging equipment and other harsh environmental application. 相似文献
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A diaphragm-based interferometric fiberoptic sensor that uses a low-coherence light source was designed and tested for on-line detection of the acoustic waves generated by partial discharges inside high-voltage power transformers. The sensor uses a fused-silica diaphragm and a single-mode optical fiber encapsulated in a fused-silica glass tube to form an extrinsic Fabry-Perot interferometer, which is interrogated by low-coherence light. Test results indicate that these fiber optic acoustic sensors are capable of faithfully detecting acoustic signals propagating inside transformer oil with high sensitivity and wide bandwidth. 相似文献
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《IEEE transactions on instrumentation and measurement》2009,58(12):4001-4011
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Phuong Dinh Tam Hoang Sy Hong Nguyen Van Hieu 《Journal of Experimental Nanoscience》2014,9(7):652-660
A novel, portable, electrical detection system was constructed for DNA sensor application to detect DNA hybridisation. The read-out circuit consists of an analogue circuit and a digital circuit. The analogue circuit with an IC MAX038 generates a sine wave with a constant frequency (10?kHz), which serves as the input for the DNA sensor. The DNA sensor consists of active and reference sensors. DNA hybridisation between the DNA probe and the target sequences causes changes in the conductance of the conductive membrane (DNA/MWCNTs) on the sensor surface, which lead to changes in the amplitude of the sine wave from the sensor output compared with that of the reference signal output (input sine wave). We used a digital circuit with a microprocessor (PIC33FJ256MC710) to determine the change in the amplitude of the sine wave signal of the sensor. From these digital data, the difference in the amplitudes of the active and reference sensors was calculated and displayed on the liquid crystal display. Measurement results show that the portable electrical detection system can detect DNA target concentrations as low as 0.16?µM. The detection of the amplified polymerase chain reaction sample and the reproducibility of the DNA sensor results were also determined using the designed readout circuit. The proposed electrical detection system is suitable for DNA sensor application. 相似文献
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齿轮箱润滑油液中的磨粒携带了大量磨损状态的信息,通过在线监测传感器能监测出油液中磨粒的相关参数(尺寸、数量、生成率等),可判断或推测出齿轮箱的磨损状态。然而,目前在线监测的磨粒相关特征参数与齿轮箱磨损状态的准确对应关系还未得到深入研究。本研究首先采用离线检测的方法验证了在线监测传感器的可靠性,然后通过自主研制的试验台进行了齿轮箱全寿命加速试验,根据不同尺寸磨粒数量、磨粒生成率等的变化趋势对齿轮箱磨损程度做出了预判;最后采用铁谱分析法进一步验证了在线监测齿轮箱故障的准确性。结果表明:基于油液在线监测的磨粒信息(尺寸、数量、生成率)能很好地对齿轮箱磨损状态进行判定和预测。 相似文献
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A highly sensitive surface plasmon resonance (SPR) biosensor employing magnetic nanoparticle (MNP) assays is presented. In the reported approach, MNPs simultaneously served as "vehicles" for rapid delivery of target analyte from a sample to the sensor surface and as labels increasing the measured refractive index changes that are associated with the binding of target analyte. An optical setup based on grating-coupled surface plasmon resonance (GC-SPR) was used with a magnetic field gradient applied through the sensor chip for manipulating with MNPs on its surface. Iron oxide MNPs and a sensor surface with metallic diffraction grating were modified with antibodies that specifically recognize different epitopes of the analyte of interest. The sensitivity of the biosensor was investigated as a function of mass transport of the analyte to the sensor surface driven by diffusion (free analyte) or by the magnetic field gradient (analyte bound to MNPs). Immunoassay-based detection of β human chorionic gonadotropin (βhCG) was implemented to evaluate the sensitivity of the MNP-enhanced GC-SPR biosensor scheme. The results reveal that the sensitivity of βhCG detection was improved by 4 orders of magnitude compared with the regular SPR sensor with direct detection format, and a limit of detection below pM was achieved. 相似文献
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Goutam Koley Jie Liu Md. W. Nomani Moonbin Yim Xuejun Wen Tain-Yen Hsia 《Materials science & engineering. C, Materials for biological applications》2009,29(3):685-690
We demonstrate the application of polydimethylsiloxane (PDMS) thin films in highly sensitive pressure and oxygen sensors, designed for pressure and oxygen content measurements within the heart and blood vessels. PDMS thin film displacement as a result of pressure changes was transduced by a capacitive detection technique to produce quantitative measurement of absolute pressures. Oxygen measurements were obtained by transducing the current change between a Pt and an Ag/AgCl electrode on a glass substrate, with KCl soaked filter paper as the electrolytic media that is separated from the oxygen carrying fluid by a thin PDMS membrane. The best sensitivity for the pressure sensor was ~ 0.1 nA/KPa, with a noise limited resolution of ~ 0.09 KPa. For the oxygen sensor, the best sensitivity was ~ 2.75 µA for 1% change in oxygen content of the surrounding media, with a noise limited resolution of ~ 6.18 ppm oxygen. These experimental results agree with theoretical modeling predictions, and suggest that the semi-permeable and biocompatible PDMS can be successfully adopted as the contacting membrane in an integrated sensor design to quantify pressure and oxygen content in blood. 相似文献
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多孔介质的有效应力定律广泛应用于流固耦合变形分析问题。该文考虑孔隙的重数、孔隙流体的相数、各向异性、非饱和、基质吸力等条件,提出了广义多相非饱和多重孔隙介质的有效应力定律。在固体相及各流体相线弹性变形的假设下,首先通过应力状态分解、边界条件叠加方法,得到了不考虑基质吸力的多相等效饱和各向异性多重孔隙介质的有效应力。考虑到非饱和多孔介质中两相界面张力引起的基质吸力,在线弹性变形基础上,叠加了基质吸力引起的变形部分,推导得到非饱和多孔介质的有效应力定律的一般形式。将所得公式根据实际需要进行简化处理,可以得到目前常用的有效应力定律的表达形式,充分说明了该文所得结论的合理性。 相似文献