共查询到20条相似文献,搜索用时 15 毫秒
2.
稠油在我国已探明的储量中占比50%以上,而它的高密度、高黏度等特征使得其开采和运输的难度极大,因此,稠油降黏意义重大。超声波技术在稠油降黏的应用中已取得了一定的成效,但尚未得到现场大规模应用。为探究超声波在稠油降黏过程中的作用规律,基于室内实验设计了包括超声波发生器、流变仪、电子天平、恒温水浴等仪器组成的超声稠油降黏评价测试平台。在测试平台上,观测了超声波发生器的电功率、超声作用时间以及油样初始黏度对稠油降黏效果的影响。结果表明,只有在一定的条件下,超声波技术在稠油降黏中的应用才能取得较好的效果,说明了超声波技术对于稠油降黏以及油井的增产增注具有适用性。目前看来,超声波降黏技术在油田现场实际井中的应用及其降黏机理还需进一步深入的研究。 相似文献
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本文工作的目的是欲获得换参器的高分辨率,追求最为理想的响应波形-单极脉冲,单极脉冲的获得需要同时考虑换能器自身的匹配情况及发射,接收电源的状态,本文工作的第一部分用Mason等效电路对单极脉冲的获得进行了理论分析,第二部分进行了电源的改造工作,得到与理论计算相符合的实验结果。 相似文献
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S. R. Murthy 《Bulletin of Materials Science》2001,24(6):611-616
Polycrystalline NiZn ferrites with different grain sizes (1.2 (Am to 10.2 (Am) were prepared by the usual ceramic method.
The magnetic properties were measured at room temperature. The ultrasonic velocity and attenuation were measured on Ni-Zn
ferrite by using the pulse transmission method at 1 MHz, in the temperature range 300–600 K. The velocity was found to be
slightly sample dependent at room temperature and decreased with increasing temperature, except near the Curie temperature,
T
c
,where a small anomaly was observed. The longitudinal attenuation (α
1
)at room temperature was found to be more sample dependent. The temperature variation of ultrasonic longitudinal attenuation
exhibited a broad maximum around 400 K and a sharp maximum just below Curie temperature (
T
c
).The above observations were carried out in the demagnetized state. The application of a 380 mT magnetic field allowed us to
reach the saturated state of the sample at all the measuring temperatures. The anomaly observed in the thermal variation of
velocities (longitudinal and transverse) and attenuation has been qualitatively explained with the help of the temperature
variation of the magneto-crystalline anisotropy constant. 相似文献
5.
O. Vigil-Galán E. Marín J-Sastré Hernández E. Saucedo C. M. Ruiz G. Contreras-Puente A. Calderón 《Journal of Materials Science》2007,42(17):7176-7179
We show that the Photo-Acoustic Spectroscopy (PAS) is an useful alternative method for the determination of the optical-absorption
coefficient of CdTe thin films, in the spectral region near to the fundamental absorption edge, ranging from 1.0 eV to 2.4 eV,
using an open cell in the transmission configuration. We applied this method to the optical characterization of CdTe layers
for several values of their thickness. These CdTe samples were deposited by closed-space vapor transport (CSVT) technique
under different growth conditions. 相似文献
6.
基于夹心式压电换能器基本原理,设计了一种可用于井口重油降粘和高凝油降凝的工业规模应用的大功率压电超声换能器,其工作频率为16.86 kHz,输入电功率为500 W,可在100℃高温环境下长时间连续工作。首先根据工作环境需要设计了换能器模型,结合等效电路法和传输矩阵法,计算了换能器满足谐振频率条件的各部分参数;通过有限元仿真软件ANSYS对换能器进行了模态分析和谐响应分析,确定了换能器的最佳工作模态和工作频率。根据仿真模型,制作了工程样机,通过阻抗分析仪测得其实际的工作频率与仿真结果的误差为0.5%。这种大功率压电超声换能器有望在重油降粘以及超声处理工业中得到规模化应用。 相似文献
7.
目前基于脉冲技术的超声测温研究主要侧重于超声换能器和系统硬件电路设计,而对高温敏感元件的研究较少。通过选取合适的敏感元件材料,以及对超声导波在杆中的频散特性和反射、透射分析,最终选用了一根长为1 m、直径1 mm左右的带反射凹槽的钍钨杆作为敏感元件,并在一个超声测温平台进行了初步的实验。实验结果表明,采用钍钨合金杆作为敏感元件,可有效测量12℃~1 600℃声速与温度的关系,所测得的高温下的声速与参考值相比误差不超过0.68%。 相似文献
8.
Pratik Nayak 《International Journal of Pavement Engineering》2017,18(7):595-607
Recycling of highway materials is an effort to preserve the natural environment, reduce waste and provide a cost-effective way for construction of highways. The reclaimed asphalt pavement (RAP) contains stiffened binder caused by loss of volatile materials and oxidation. Hence, the addition of high amount of the RAP to asphalt mix may make it prone to fatigue failure. Due to this reason, addition of RAP to asphalt mixture in substantial amount has been a challenge so far. Therefore, ‘rejuvenators’ which are supposed to restore chemical and physical properties of the aged asphalts are used effectively in asphalt mixture. In this study, two locally available oils, i.e. pongamia oil (locally known as Karanja oil) derived from the seeds of Pongamia pinnata and a composite rejuvenator made of castor oil and coke oven gas condensate have been explored for rejuvenating the aged binder. The rheological properties of aged binder and rejuvenated binders were studied using a dynamic shear rheometer. From the various rheological tests conducted, it was found that certain proportion of pongamia oil as well as composite castor oil was able to impart desirable rutting as well as fatigue performance for the rejuvenated binder samples. The thermal analysis carried out using thermogravimetric analysis ensured adequate thermal stability for the binder specimens treated with these oils. In terms of binder performances, it was found that these oils could be considered as suitable rejuvenators for effectively restoring properties of the aged binder. Performance studies on RAP mixes may be extended for recommending these two oils as rejuvenators for hot mix pavement recycling. 相似文献
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以委内瑞拉超重油和新疆风城超重油为研究对象,进行了超声辅助降粘的研究。在实验中,制备了两类四种实验样品:分别掺入20%和30%柴油的两种委内瑞拉超重油样品、在O/W降粘体系下制备的委内瑞拉超重油样品和风城超重油样品。使用频率为18 k Hz的超声变幅杆和24 k Hz的超声清洗槽对上述四种实验样品进行超声处理,结果表明:1)对掺入20%和30%柴油的委内瑞拉超重油,经过超声处理的超重油样品在20℃时粘度分别增高了25%和15%以上;2)在O/W降粘体系超重油降粘中,风城超重油样品经过超声作用后,在20℃粘度降低了25%以上,而降粘剂的使用量可减少20%,超声辅助降粘效果明显;3)在O/W降粘体系超重油降粘中,委内瑞拉超重油样品经过超声处理后,在14℃时,超声处理过的样品的粘度降低不高于25%,在高于这一温度的情况下则未观察到明显的粘度降低。文中对上述实验结果产生的原因进行了定性的分析。 相似文献
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《中国计量学院学报》2018,(1):14-19
对与球罐材质相近,厚度、坡口形式和焊接工艺相同定制的对接焊缝试块,利用超声衍射时差法(TOFD)检测技术和超声相控阵检测技术进行检测,分析比较两种方法的检测结果.实验结果表明,超声TOFD检测可以高效和精确地检测出焊缝中的缺陷,但它存在近表面和近底面盲区;超声相控阵检测可以借助探头声束的聚焦和可转向的特点,检测出焊缝近表面和近底面的缺陷.因此,将两种检测方法结合使用,可以有效提高焊缝近表面检测效果,提高缺陷的检出率,实现缺陷的精确定位和定量. 相似文献
16.
Ludwig R Lord W 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1988,35(6):809-820
The authors present a finite-element formulation for an overall ultrasonic NDT (nondestructive testing) system, including appropriate models for transmitter and receiver transducers. Transducer considerations are discussed. Results are given for two-dimensional plane-strain geometry simulations that agree qualitatively with corresponding experimental measurements and show the potential of the method. 相似文献
17.
为研究挤压加工时静压力、进给量和挤压速度等工艺参数对试件表面质量的影响,在挤压加工中引入纵-弯复合振动后对Q235钢轴件端面进行处理,并与普通挤压加工进行对比,基于正交试验结果构建了挤压加工后表面粗糙度和表面里氏硬度二次回归预测模型.试验发现:在相同加工工艺参数下,在普通挤压加工中引入纵-弯复合超声振动后获得的表面粗糙度Ra值更小,而表面里氏硬度值显著提高;采用两种挤压加工方法后工件表面粗糙度Ra值均随着静压力和进给量的增加而增大,而挤压速度的影响很小,进给量对表面粗糙度的影响最为显著;工件经超声挤压加工时静压力越大,则获得的表面硬度越大,且表面硬度随进给量的增大先增大后减小,而普通挤压加工后表面硬度随静压力和进给量的增大先增后减,且在两种加工方式下工件表面硬度基本不受挤压速度的影响.纵-弯复合振动超声挤压加工工艺适合Q235钢表面强化处理,构建的表面粗糙度和硬度的预测模型可用于指导Q235钢表面强化处理工艺生产. 相似文献
18.
一种大功率超声振动子的实验研究 总被引:1,自引:0,他引:1
本文给出了一种大功率超声振动子的基本结构,从波动方程出发推导了各分段的位移及应变的表达式,同时给出了频率方程。采用微机辅助设计可计算出各点的位移值,应变值和尺寸。在研制过程中作者对国内传统的结构设计和装配工作作了较大的改进,理论值和实测值非常接近。本文所述振动子完全可以代替进口振动子,某些性能指标还超过进口同类产品。 相似文献
19.
Deconvolution reconstruction of full-view and limited-view photoacoustic tomography: a simulation study 总被引:1,自引:0,他引:1
Zhang C Wang Y 《Journal of the Optical Society of America. A, Optics, image science, and vision》2008,25(10):2436-2443
Although many algorithms are available for full-view photoacoustic tomography (PAT), no exact and stable algorithm for limited-view PAT has been proposed. In this paper the deconvolution reconstruction (DR) algorithm is proposed for both full-view and limited-view PAT. In the DR algorithm, first a new function is constructed from detected photoacoustic signals and approximately simplified, and then the tissue's electromagnetic absorption is derived from this function on the basis of Fourier-based deconvolution. Computer simulations are carried out to compare the DR algorithm with two popular PAT algorithms, the time-domain reconstruction (TDR) and the filtered back projection (FBP). Although the error of the DR algorithm increases with the size of the detected object, it is shown that the DR algorithm has good precision and strong robustness to noise in the full-view PAT, nearly equivalent to the TDR and FBP. Yet the DR algorithm is more than ten times faster in computation speed. In the limited-view PAT, the DR is superior to the TDR and FBP in terms of both accuracy and robustness to noise. 相似文献