表面活性剂对低渗透油藏渗吸的影响

采用不同类型的表面活性剂进行自发渗吸实验,并对表面活性剂改善岩石润湿性、降低界面张力的能力进行了分析。实验结果表明,阴离子型表面活性剂改善润湿性的能力好于其他类型的表面活性剂,且在岩心中的自发渗吸效果最好,这是由于阴离子型表面活性剂改善润湿性的机理为离子对形成机理,强于阳离子的吸附机理;接触角是决定渗吸能否发生的决定性因素,只有接触角小于70°时渗吸才能发生;界面张力影响渗吸速度和最终采出程度,对于渗透率为1 mD的岩心,最佳界面张力为10~(-1) mN/m。     

积分中值屈服准则解析厚板轧制椭圆速度场

为解决非线性Mises比塑性功率积分困难以及由此导致的轧制功率解析式难以获得的问题,本文通过建立并利用线性比塑性功率表达式对提出的椭圆速度场进行能量分析,得到了轧制力能参数的解析解.文中通过对变角度屈服函数求积分中值,构建了一个新的屈服准则,它是主应力分量的线性组合,在π平面上的轨迹是逼近Mises圆的等边非等角的十二边形,其基于Lode参数表达式的理论结果也与实验数据吻合较好.同时,根据厚板轧制时金属流动速度从入口到出口逐渐增大的特点,提出了水平速度分量满足椭圆方程的速度场,该速度场满足运动许可条件.通过相应的轧制能量分析,获得了基于线性屈服准则的内部变形功率以及基于应变矢量内积法上的摩擦功率与剪切功率.在此之上,通过泛函的极值变分导出了轧制力矩、轧制力以及应力状态系数的解析解,并与现场实测数据进行了对比,结果表明利用本文提出的屈服准则与速度场所建立的轧制力矩与轧制力模型与实测值吻合较好,其中轧制力误差小于5.3%,轧制力矩误差在6%左右.     

Thermal and transport properties of as-grown Ni-rich TiNi shape memory alloys

Electrical resistivity, Seebeck coefficient, specific heat and thermal conductivity measurements on the Ti_50−xNi_50+x (x = 0.0–1.6 at.%) shape memory alloys are performed to investigate their thermal and transport properties. In this study, anomalous features are observed in both cooling and heating cycles in all measured physical properties of the slightly Ni-rich TiNi alloys (x ≤ 1.0), corresponds to the transformation between the B19′ martensite and B2 austenite phases. Besides, the transition temperature is found to decrease gradually with increasing Ni content, and the driving force for the transition is also found to diminish slowly with the addition of excess Ni, as revealed by specific heat measurements. While the signature of martensitic transformation vanishes for the Ni-rich TiNi alloys with x ≥ 1.3, the characteristics of strain glass transition start to appear. The Seebeck coefficients of these TiNi alloys were found to be positive, suggesting the hole-type carriers dominate the thermoelectric transport. From the high-temperature Seebeck coefficients, the estimated value of Fermi energy ranges from ∼1.5 eV (Ti_48.4Ni_51.6) to ∼2.1 eV (Ti₅₀Ni₅₀), indicating the metallic nature of these alloys. In addition, the thermal conductivity of the slightly Ni-rich TiNi alloys with x ≤ 1.0 shows a distinct anomalous feature at the B19′ → B2 transition, likely due to the variation in lattice thermal conductivity.     

菌型叶根动叶片叶根叶冠内径向的加工

菌型叶根动叶片是一种新型的动叶片,采用数控铣加工叶根内径向面时留0.1~0.2mm余量,然后在进行叶根内径向磨削,叶冠直接加工到位,没有后序磨削加工,由于叶根叶冠在加工过程中不是一次装夹完成的,根冠存在一定的落差,在后续的装配中容易产生配合间隙,无法达到要求。文中介绍了一种新的加工工艺,解决了这一问题。     

Contribution of metal vapor mass at periphery part of pulsed arc to electromagnetic force in weld pool

The arc welding has been used in various welding methods because it is inexpensive and high in strength after welding. However, it is a problem that accidents such as collapse of the bridge occur because of the welding defects. The welding of low cost and high productivity is required without the welding defects. The pulsed TIG welding is inexpensive and capable of high‐quality welding. The electromagnetic force contributing to penetration changes because the transient response of arc temperature and iron vapor generated from anode occurs. However, the analysis of pulsed TIG welding with metal vapor has been elucidated only metal vapor concentration near anode with transient phenomenon and heat flux. Thus, the theoretical elucidation of penetration depth with control factor has not been researched. In this paper, the contribution of metal vapor mass at the periphery part of pulsed arc to the electromagnetic force in the weld pool is elucidated. As a result, the iron vapor mass at periphery part decreased with increasing the frequency. The iron vapor was stagnated at axial center within one cycle. The electromagnetic force to the penetration depth direction in weld pool increased at axial center. Therefore, the metal vapor mass at periphery part plays an important role for the electromagnetic force increment at axial center.     

Numerical Investigation of the Capture of Polydisperse Particles by Charged Droplets

The capture of particles by charged droplets was simulated by considering the electrostatic interactions of droplet-droplet and droplet-particle. The results indicate that the electrostatic repulsion between droplets leads to a dynamic accumulation mode of particles. However, the droplet spacing has an insignificant effect on the capture efficiency when the electrostatic deposition predominates. The increase of droplet charge remarkably improves the capture efficiency, in which the capture of fine particles accounts for the largest proportion. Compared to the droplet charge, the droplet size shows a limited improvement in the capture efficiency. Reducing the droplet velocity prolongs the capture time instead of enhancing the capture capacity per unit time, thereby improving capture efficiency.     

Ergonomically based design of tractor control tools

Musculoskeletal injuries are well-known disorders among the agricultural tractor operators. Overexertion is a critical factor which can agitate these injuries. Physical body characteristics should be measured for an ergonomically best-fit-optimal design for the operators. In this study, a designed setup was employed to derive the applied forces by tractor operators on the control tools. The different muscle strengths including leg/foot strength, hand push/pull strength, and torque strength applied by both hands were measured. A comparison was made for the obtained values for different strengths by considering the effects of hand dominance. The obtained data were used to estimate the maximum allowed forces in these tools. In contrast to the previous studies, the minimum allowed actuating forces of the pedals were calculated using reasonable assumptions. These values could provide more comfort and less exhaustion for the tractor operators. The obtained ranges were benchmarked against corresponding recommended values in some standards (ISO, ISIRI, and ASABE family). The results revealed the unsuitability of evaluated standards for a proper design and the excessive overestimation of those recommended values (in some cases more than 3 times). In all of the design procedure, a suitable attention was paid to accommodate it with more than 90% of target population.Relevance to industryA prosperous industry which considers ergonomic factors in the design of agricultural machine workplace can overcome the disorders and generate more comfort. Evaluating more exact mechanical forces can result in a suitable design of workplace.     

Quantitative investigation of electromechanical coupling of potassium sodium niobate-based thin films

High-performance environment-friendly piezoelectric potassium sodium niobate (KNN)-based thin films have been emerged as promising lead-free candidates, while their substrate-dependent piezoelectricity faces the lack of high-quality information due to restraints in measurements. Although piezoresponse force microscopy (PFM) is a potential measuring tool, still its regular mode is not considered as a reliable characterization method for quantification. After combining machine-learning enabled analysis using PFM datasets, it is possible to measure piezoelectric properties quantitatively. Here we utilized advanced PFM technology empowered by machine learning to measure and compare the piezoelectricity of KNN based thin films on different substrates. The results provide a better understanding of the relationship between structures and piezoelectric properties of the thin films.