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In this paper, we obtain a refined temporal asymptotic upper bound of the global axially symmetric solution to the Boussinesq system with no thermal diffusivity. We show the spacial $W^{1,p}$-Sobolev ($2\leq p, 22 pages, all comments are welcome

In this paper, we will solve the Leray's problem for the stationary Navier-Stokes system in a 2D infinite distorted strip with the Navier-slip boundary condition. The existence, uniqueness, regularity and asymptotic behavior of the solution will be investigated. Moreover, we discuss how the friction coefficient affects the well-posedness of the solution. Due to the validity of the Korn's inequality, all constants in each a priori estimate are independent of the friction coefficient. The main novelty is the total flux of the velocity can be relatively large (proportional to the {\it slip length}) when the friction coefficient of the Navier-slip boundary condition is small, which is essentially different from the 3D case., 45 pages. arXiv admin note: text overlap with arXiv:2204.10578. A remark is added to state the independent accomplishment of solving the 2D Leray's problem with the Navier-slip boundary condition by our group and Professor Chunjing Xie's group

Shale oil reservoirs are more complex and difficult to exploit than conventional and tight oil reservoirs because of low porosity, permeability, and rich organic matter. The presence of organic mat...

The original Leray's problem concerns the well-posedness of weak solutions to the steady incompressible Navier-Stokes equations in a distorted pipe, which approach to the Poiseuille flow subject to the no-slip boundary condition at spacial infinity. In this paper, the same problem with the Navier-slip boundary condition instead of the no-slip boundary condition, is addressed. Due to the complexity of the boundary condition, some new ideas, presented as follows, are introduced to handle the extra difficulties caused by boundary terms. First, the Poiseuille flow in the semi-infinite straight pipe with the Navier-slip boundary condition will be introduced, which will be served as the asymptotic profile of the solution to the generalized Leray's problem at spacial infinity. Second, a solenoidal vector function defined in the whole pipe, satisfying the Navier-slip boundary condition, having the designated flux and equalling to the Poiseuille flow at large distance, will be carefully constructed. This plays an important role in reformulating our problem. Third, the energy estimates depend on a combined $L^2$ estimate of the gradient and the stress tensor of the velocity.

CO2 miscible displacement is an efficient method for enhanced shale-oil recovery. Understanding the movability of shale oil in different states of occurrence is important for CO2 miscible displacem...

The adsorbed and dissolved oil in the shale reservoirs can be produced during CO2 injection. However, the effects of different factors on the adsorption and dissolution behaviors of CO2 and oil mixtures in the shale were unclear, such as the oil composition, shale properties and temperature. In this study, a series of adsorption and dissolution tests of CO2 and different n-alkane mixtures in organic-rich shales were performed under different condition. The effects of the alkane type, shale properties and temperature on the adsorption and dissolution amount of mixtures and the replace ability of CO2 to n-alkane were discussed, respectively. The results indicate that the dissolution amount was decreased with the chain length of alkane and increased with TOC and temperature. The adsorption amount of the mixtures in shale was low and only account for 3–16% of total adsorption and dissolution amount, which mainly depended on the specific surface area of the shale samples. Additionally, the replace ability of CO2 to dissolved n-alkane was decreased with the chain length of alkane and temperature. However, there are no obvious rules between the replace ability with TOC of shale. This study can provide useful information for EOR of shale oil reservoirs by CO2 injection and the geological storage of CO2 in shale oil reservoir.

Rheological behaviors of microbial polysaccharides with different substituents in aqueous solutions have been systematically investigated. Both the saccharide side chains and acetyl substituents improve the gelation of welan gum (WG), diutan gum (DG) and gellan gum (GG) in pure water at 25 °C. For the polysaccharides with saccharide side chains (WG and DG), the relationship between the apparent viscosity and concentration conforms to the linear equation, while that of the polysaccharide with acetyl (GG) is exponential. More importantly, the roles of substituents on the stability of the molecular conformation of polysaccharides are significantly depended on the surrounding environment. Disaccharide side chains promote the stability of helical conformation and gel aggregates of GG at high temperature (85 °C) or in the presence of inorganic salts with the ionic strength of 2.0 mol L−1. The stability of gel structure containing acetyl (GG) shows higher temperature/salt sensitivity. Additionally, deacylated gellan gum (GG(d)) solutions transform into hydrogels in the presence of dodecyltrimethylammonium bromide (DTAB). This study will help to obtain a better understanding on the rheological properties of polysaccharides with respect to the conformation and applications.

AC/DC power electronic transformer is the core of the energy conversion device as a micro grid having a multi-port, high-capacity, high efficiency functions. Bipolar failure is one of the typical failures, causing the system does not work. This article aims to analyze the post bipolar DC microgrid faults in the AC/DC power electronic transformer is proposed to suppress over-voltage topology, analyzes the effects of lightning on the drive characteristics of a fault, and consider the safety of the system in order to run, reliability and economy, designed arrester parameters for the arrester between the valve outlet and the neutral point commutation. The energy simulation calculation of the arrester was carried out, and the effectiveness of the selection and configuration method of the arrester was verified by building a simulation platform that does not affect the normal operation. Suppressing the sub-module voltage can provide a reference for the selection of main equipment and insulation coordination.

Smooth solutions of the stationary Navier-Stokes equations in an infinitely long pipe, equipped with the Navier-slip or Navier-Hodge-Lions boundary condition, are considered in this paper. Three main results are presented. First, when equipped with the Navier-slip boundary condition, it is shown that, $W^{1,\infty}$ axially symmetric solutions with zero flux at one cross section, must be swirling solutions: $u=(- C x_2, C x_1,0)$, and $x_3-$periodic solutions must be helical solutions: $u=(-C_1x_2,C_1x_1,C_2)$. Second, also equipped with the Navier-slip boundary condition, if the swirl or vertical component of the axially symmetric solution is independent of the vertical variable $x_3$, solutions are also proven to be helical solutions. In the case of the vertical component being independent of $x_3$, the $W^{1,\infty}$ assumption is not needed. In the case of the swirl component being independent of $x_3$, the $W^{1,\infty}$ assumption can be relaxed extensively such that the horizontal radial component of the velocity, $u_r$, can grow exponentially with respect to the distance to the origin. Also, by constructing a counterexample, we show that the growing assumption on $u_r$ is optimal. Third, when equipped with the Navier-Hodge-Lions boundary condition, we can show that if the gradient of the velocity grows sublinearly, then the solution, enjoying the Liouville-type theorem, is a trivial shear flow: $(0,0,C)$., Comment: Compared to the previous version, title is chagned. Two new resutls is added and one result is improved. Also one new contributed author is added

In this paper, we consider regularity criteria of a class of 3D axially symmetric MHD-Boussinesq systems without magnetic resistivity or thermal diffusivity. Under some Prodi-Serrin type critical assumptions on the horizontal angular component of the velocity, we will prove that strong solutions of the axially symmetric MHD-Boussinesq system can be smoothly extended beyond the possible blow-up time $T_\ast$ if the magnetic field contains only the horizontal swirl component. No a priori assumption on the magnetic field and the temperature fluctuation is imposed., 20 pages, all comments are welcome

The anti-vignetting glass (AVG) is the key material for super-second and third-generation low-light image intensifiers. With the development of low-light night vision technology, the requirements of high precision and low damage are put forward to AVG. However, traditional measurement methods, such as vernier calipers, micrometers, dial indicators, etc., are all contact measurement, which will inevitably cause damage to AVG during the measurement process. They cannot meet the technical requirements for low damage. Non-contact measurement technology is a non-destructive testing method that realizes the geometric measurement of AVG by writing measurement programs and setting measurement parameters. However, due to the special structure of AVG, the non-contact measurement technology has measurement errors and cannot meet the high-precision measurement requirements. In this paper systematically analyzes the causes of errors in non-contact measurement technology by studying the characteristics of the light source, the difference in light intensity, and the way of grabbing contour edges. Through the error correction technology, the error of the non-contact measurement technology is eliminated, the AVG high-precision and low-damage non-destructive testing is realized.

Through the influence of the temperature, concentration, acid type and acid dissolution time of the acid solution on the acid etching speed of the multi-fiber and the surface quality after acid etching, the acid dissolution mechanism of the acid solution flexible optical fiber image bundle is discussed. The weight loss method was used to test the acid dissolution rate of different acid-soluble glasses, combined with the breakage of the multi-fiber after acid dissolution, to study the effect of acid-soluble glass on the image quality of the flexible optical fiber image bundle. The experimental results show that using a suitable acid solution, a suitable acid solution concentration, a suitable temperature and a reasonable acid dissolution time has obvious effects on reducing the broken wire rate of the flexible optical fiber image bundle and improving the image transmission quality.

Flexible DC transmission lines have been used in some parts of the northern China electric power system. Due to unstable centralized penetration of renewable generators, pumped storage power stations have also been established to enhance the flexibility of the power system. This paper proposes a dispatch method for AC/DC hybrid power systems with flexible DC transmission lines and pumped storage power stations. In the proposed dispatch model, the objective contains transmission cost, generation cost, and penalty cost. Constraints of flexible DC transmission lines, pumped storage power stations, as well as regular generator and system-wide dispatch constraints are considered. Case studies demonstrate that the proposed model can handle unstable power outputs of renewable generators by pumped storage power stations, eliminate renewable generator variations, and regularize the transmission power to load center.

CO2 cyclic injection is a promising method for enhanced shale oil recovery. However, the enhanced shale oil recovery mechanism is unclear, especially the adsorption and dissolution of CO2 and oil in kerogen. Therefore, it is of great importance to study the adsorption and dissolution mechanisms of CO2 and oil mixtures in shale. In this study, a new experimental apparatus was designed to test the change in the mole fractions of CO2 and oil before and after adsorption and dissolution at equilibrium conditions. For simplicity, n-dodecane (n-C12) was used as the oil. The adsorption and dissolution amounts of CO2 and n-C12 were obtained using a mathematical method. Moreover, the adsorption and dissolution characteristics of the CO2 and n-C12 mixtures in shale and the effect of pressure on the adsorption and dissolution amounts were studied. Finally, the swelling factor of the shale, which was caused by the dissolution of the mixtures, was calculated from the experimental results. The results show that dissolve...

Unlike melody extraction and other aspects of music transcription, research on playing technique detection is still in its early stages. Compared to existing work mostly focused on playing technique detection for individual single notes, we propose a general end-to-end method based on Sound Event Detection by FCN for musical instrument playing technique detection. In our case, we choose Erhu, a well-known Chinese bowed-stringed instrument, to experiment with our method. Because of the limitation of FCN, we present an algorithm to detect on variable length audio. The effectiveness of the proposed framework is tested on a new dataset, its categorization of techniques is similar to our training dataset. The highest accuracy of our 3 experiments on the new test set is 87.31%. Furthermore, we also evaluate the performance of the proposed framework on 10 real-world studio music (produced by midi) and 7 real-world recording samples to address the ability of generalization on our model., Submitted to ICASSP 2020

We propose an algorithm that is capable of synthesizing high quality target speaker's singing voice given only their normal speech samples. The proposed algorithm first integrate speech and singing synthesis into a unified framework, and learns universal speaker embeddings that are shareable between speech and singing synthesis tasks. Specifically, the speaker embeddings learned from normal speech via the speech synthesis objective are shared with those learned from singing samples via the singing synthesis objective in the unified training framework. This makes the learned speaker embedding a transferable representation for both speaking and singing. We evaluate the proposed algorithm on singing voice conversion task where the content of original singing is covered with the timbre of another speaker's voice learned purely from their normal speech samples. Our experiments indicate that the proposed algorithm generates high-quality singing voices that sound highly similar to target speaker's voice given only his or her normal speech samples. We believe that proposed algorithm will open up new opportunities for singing synthesis and conversion for broader users and applications., Comment: Submitted to ICASSP-2020

In this paper, we study the finite-time blow up of solutions to the following semilinear wave equation with time-dependent damping \[ \partial_t^2u-\Delta u+\frac{\mu}{1+t}\partial_tu=|u|^p \] in $\mathbb{R}_{+}\times\mathbb{R}^n$. More precisely, for $0\leq\mu\leq 2,\mu \neq1$ and $n\geq 2$, there is no global solution for $1, Comment: 11 pages

According to the characteristics of duplicate web pages in the meta search engine, a duplicate web pages detection algorithm is proposed based on a web page URL, title and abstract, and according to their different characteristics, different similarity computing method is proposed, firstly, the page URL is standardization processed in the algorithm, and then for the title detection, the algorithm improves the title string fuzzy matching algorithm and calculate the similarity based on the word frequency of each items in the query, for the abstract judgment, similarity computing is in accordance with the sentences of the abstract, for each sentence the algorithm gives three weights, and calculates the weights of similarity on base of each summary statement, the effect of the algorithm is obvious, it has been verified by experiment that the algorithm is superior to the traditional algorithm in the precision and recall rate.