Numerical investigation on dynamic characteristics of drilling shaft in deep hole drilling influenced by minimal quantity lubrication

The dynamic characteristics of drilling shaft in deep hole drilling influenced by minimal quantity lubrication (MQL) is investigated. According to the features of the compressible fluid Reynolds equation in oil/air feature, a time-dependent mathematical model is established to describe the pressure distribution of cutting fluid with nonlinearity in MQL deep hole drilling. By introducing the differential transformation approach, the time-dependent pressure equation arising from cutting fluid is solved by the use of direct integral method. The influences of the rotational speed, the transverse displacement ratio, and radial clearance on the hydrodynamic pressure distribution of cutting fluid are obtained. The advantage of this method is to overcome much of the computational cost and has its rapid convergence rate. Furthermore, the nonlinear responses of drilling shaft influenced by MQL are analyzed, and the instability rotational speeds of drilling tool are discussed while the design parameters of drilling shaft system changing.     

Facile preparation of polyethylene glycol/wood-flour composites as form-stable phase change materials for thermal energy storage

Journal of Thermal Analysis and Calorimetry - The polyethylene glycol/wood-flour (PEG/WF) composites were synthesized as novel form-stable phase change materials (PCMs) using PEG as phase change...     

Effect of tungsten oxide loading on metathesis activity of ethene and 2-butene over WO<Subscript>3</Subscript>/SiO<Subscript>2</Subscript> catalysts

The metathesis of ethene and 2-butene to propene was studied over WO₃/SiO₂ catalysts with various WO₃ loadings (2, 4, 8, 12, 16, and 24 wt%). The 2-butene conversion and propene selectivity increased greatly with WO₃ loading increasing from 2 to 8 wt%, reached maximum at 8–12 wt% WO₃ loading, and then decreased when the WO₃ loading was higher than 12 wt%. From the above results and taking the economics into account, the optimal amount of WO₃ loading was ~8 wt%. The catalysts were characterized by physico-chemical and spectroscopic techniques to elucidate the effect of different tungsten oxide loadings on the metathesis reactivity of ethene and 2-butene. The characterization data indicated that three types of tungsten species (i.e., surface tetrahedral tungsten species, surface octahedral polytungstate species, and WO₃ crystallites) were present in the catalysts. It was found that WO₃ was not the active centers, and surface tetrahedral tungsten species might be more active than octahedral polytungstate species in metathesis reaction. The reduced form of tungsten species [W⁺⁴, W⁺⁵, and W^+(6−y) (0 < y < 1)] may be the suitable state of W species acting as metathesis active centers.     

Analysis on acoustic characteristics of opposed multi-burner gasifier

Hilbert–Huang Transformation and Statistical Theory are used to analyze the impinging flame noise signals of a gasifier. The characteristic of the flame noise energy is studied by standard deviation and probability density, and frequency–time distribution is generated by the empirical mode decomposition (EMD) method and Hilbert spectrum. The results show that, in different conditions, the value of standard deviation of four burners impinging flame noise is greater than that of the two burners, but not for the probability density. The change of the standard deviation and probability density of four burners is smaller than that of two burners. It means that the flame of four burners combusts severely but stably. Under the condition of low feed and oxygen ratio, the two flame burner noise signals frequency and energy distribute mainly in 100 Hz regions; and four burners flame noise distribution is concentrated in the low-frequency bands below 45 Hz and the 45–100 Hz bands.     

Generation of millimeter-wave sub-carrier optical pulse by using cascaded all-pass cavities

A novel scheme is proposed to transform an ultra-short optical pulse to a millimeter-wave frequencymodulated pulse by using the cascaded all-pass cavities （APCs）. The envelope waveform of the generated pulse train is calculated, showing effective improvement by APC cascading. The extinction ratio is analyzed with different input pulses, different cavity reflectivities, and different cascading numbers. It is shown that the cascading does not introduce much effect on the extinction ratio. Two designs by using Gires-Tournois cavity and waveguide ring resonators are proposed to realize the cascaded APC.     

The asymmetrical fractional Fourier transforms and its optical implement

Compared with the symmetrical lens system, the structure which contains double cylindrical lenses is also the basic units of a complex system and implement practical asymmetrical fractional Fourier transforms. Based on the theory of scalar diffraction and on the Fourier optics, we implement several kinds of asymmetrical fractional Fourier transforms and make the different mathematical manipulation at the corresponding coordinates, while the symmetrical system cannot. Meanwhile, the simulation experiment shows that such system not only makes the two perpendicular coordinates to be independently operated, but also increases the flexibility of the optical setup. All these characteristics make it flexible to application domain in optics.     

新型聚乙烯醇系亲和吸附剂的制备及其在糖蛋白纯化中的应 …

利用已合成的聚醋酸乙烯酯－甲基丙烯酸缩水甘油酯－甲基丙烯酸烯丙酯大孔共聚物。醇解后与６－氨基正已酸反应，进一步在ＥＤＡＣ的作用下实现与间氨基苯硼酸的偶联，得到亲水性的亲和吸附剂；配基密度为０．８６５ｍｍｏｌ／ｇ干树脂，偶联效率为８９％，以云芝糖肽八方地，吸附容量为５３．７ｍｇ／ｇ干树脂，为醇解前的７．７倍。     

Completion of R2 with a Conformal Metric as a Closed Surface

In this paper,we obtain some asymptotic behavior results for solutions to the prescribed Gaussian curvature equation.Moreover,we prove that under a con-formal metric in R2,if the total Gaussian curvature is 4π,the conformal area of R2 is finite and the Gaussian curvature is bounded,then R2 is a compact C1,α surface after completion at ∞,for any α ∈(0,1).If the Gaussian curvature has a Holder decay at in-finity,then the completed surface is C2.For radial solutions,the same regularity holds if the Gaussian curvature has a limit at infinity.     

钻柱振动信息测量技术研究进展

随着深井、超深井数量的快速增加, 钻柱振动导致的钻具失效问题更加突出. 针对钻柱振动的研究可分为理论与数值模拟、测量分析两种方法. 由于钻柱振动具有复杂的非线性特征, 使得理论与数值模拟研究受到了很大限制, 因此井下振动测量技术的研究显得尤为重要. 本文比较全面和系统地介绍了国内外钻柱振动测量技术研究现状和进展情况, 并对几个应用较为成熟的国外测量系统的工作原理、分析方法及应用技术进行了详细的综述. 所得结论可为我国井下振动测量技术的发展提供重要参考.     

Form-stable phase change materials based on castor oil and palmitic acid for renewable thermal energy storage

Journal of Thermal Analysis and Calorimetry - Utilization of renewable biomass to prepare phase change material (PCM) that can reversibly store renewable thermal energy is of great interest. Castor...