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Clinical study of NFNC in the treatment of acute exacerbation chronic obstructive pulmonary disease patients with respiratory failure

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World Journal of Clinical Cases 2023年第32期11卷 7770-7777页

作者： Xiang Chen Ling Dai Jin-Zhu Ma Xin-Xu Chu Liang Dai jian-ming liu Si-Wei Guo Xin-Wei Ru Xue-Shi Zhuang Pulmonary and Critical Care Medicine The Sixth Hospital of WuhanAffiliated Hospital of Jianghan UniversityWuhan 430000Hubei ProvinceChina Department of Intensive Care Second Unit Wuhan No.1 HospitalWuhan 430000Hubei ProvinceChina Department of Intensive Care Medicine Lixin County People's HospitalBozhou 236700Anhui ProvinceChina

BACKGROUND Most patients with acute exacerbation chronic obstructive pulmonary disease(AECOPD)have respiratory failure that necessitates active correction and the improvement of oxygenation is particularly important during treatment.High flow nasal cannula(HFNC)oxygen therapy is a non-invasive respiratory aid that is widely used in the clinic that improves oxygenation state,reduces dead space ventilation and breathing effort,protects the loss of cilia in the airways,and improves patient comfort.AIM To compare HFNC and non-invasive positive pressure ventilation in the treatment of patients with AECOPD.METHODS Eighty AECOPD patients were included in the study.The patients were in the intensive care department of our hospital from October 2019 to October 2021.The patients were divided into the control and treatment groups according to the different treatment methods with 40 patients in each group.Differences in patient comfort,blood gas analysis and infection indices were analyzed between the two groups.RESULTS After treatment,symptoms including nasal,throat and chest discomfort were significantly lower in the treatment group compared to the control group on the 3rd and 5th days(P0.05).After treatment,the same indicators were significantly improved in both patient groups but had improved more in the treatment group compared to the control group(P<0.05).After treatment,the white blood cell count,and the levels of C-reactive protein and calcitonin in patients in the treatment group were significantly higher compared to patients in the control group(P<0.05).CONCLUSION HFNC treatment can improve the ventilation of AECOPD patients whilst also improving patient comfort,and reducing complications.HFNC is a clinically valuable technique for the treatment of AECOPD.

关键词： Acute exacerbation chronic obstructive pulmonary disease HFNC Noninvasive positive pressure ventilation Application value

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Objective Omega vortex identification method

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Journal of Hydrodynamics 2019年第3期31卷 455-463页

作者： jian-ming liu Yi-sheng Gao Yi-qian Wang Chaoqun liu School of Mathematics and Statistics Jiangsu Normal University Xuzhou 221116 China Department of Mathematics University of Texas at Arlington Arlington 76019 Texas USA School of Aerospace Engineering Tsinghua University Beijing 100084 China

A new vortex identification method (liu et al. 2016) was proposed to represent the rotation relative strength and capture and visualize the vortices in our previous study. The basic idea of the Ω method is that a ratio of the vorticity squared over the summation of the vorticity squared and the deformation squared should be used to measure the relative rotation strength. However, the vorticity tensor norm is not objective. Thus, a moving observer will observe different vortex structures in a moving reference frame, which will make confusions about the real vortex structures. In the present study, by the definitions of the net spin tensor and the net vorticity vector, an objective Ω vortex identification method is presented with examples to verify that the vortex structures retain in a moving reference frame.

关键词： Vortex identification the Ω method objectivity turbulence visualization turbulence

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Galilean invariance of Omega vortex identification method

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Journal of Hydrodynamics 2019年第2期31卷 249-255页

作者： jian-ming liu Yi-qian Wang Yi-sheng Gao Chaoqun liu School of Mathematics and Statistics Jiangsu Normal UniversityXuzhou 221116China Department of Mathematics University of Texas at ArlingtonArlington 76019TexasUSA School of Aerospace Engineering Tsinghua UniversityBeijing 100084China

In the new vortex identification method(liu et al.2016)to represent the rotation level and capture and visualize the vortices,proposed in our previous study,the independence of the reference frame and the Galilean invariant were not proved.In the present study,the Galilean invariance of the omega vortex identification method is proved and several examples are presented to verify the conclusion.

关键词： Vortex identification Ωmethod.Galilean invariance turbulence visualization

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A liutex based definition and identification of vortex core center lines

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Journal of Hydrodynamics 2019年第3期31卷 445-454页

作者： Yi-sheng Gao jian-ming liu Yi-fei Yu Chaoqun liu Department of Mathematics University of Texas at Arlington Arlington Texas 76019 USA School of Mathematics and Statistics Jiangsu Normal University Xuzhou 221116 China

Six core issues for vortex definition and identification concern with (1) the absolute strength,(2) the relative strength,(3) the rotational axis,(4) the vortex core center,(5) the vortex core size, and (6) the vortex boundary (liu C. 2019). However, most of the currently popular vortex identification methods, including the Q criterion, the criterion and the Acj criterion etc., are Eulerian local region-type vortex identification criteria and can only approximately identify the vortex boundary by somewhat arbitrary threshold. On the other hand, the existing Eulerian local line-type methods, which seek to extract line-type features such as vortex core line, are not entirely satisfactory since most of these methods are based on vorticity or pressure minimum that will fail in many cases. The key issue is the lack of a reasonable mathematical definition for vortex core center. To address this issue, a liutex (previously named Rortex) based definition of vortex core center is proposed in this paper. The vortex core center, also called vortex rotation axis line here, is defined as a line where the liutex magnitude gradient vector is aligned with the liutex vector, which mathematically implies that the cross product of the liutex magnitude gradient vector and the liutex vector on the line is equal to zero. Based on this definition, a novel three-step method for extracting vortex rotation axis lines is presented. Two test cases, namely the Burgers vortex and hairpin vortices, are examined to justify the proposed method. The results demonstrate that the proposed method can successfully identify vortex rotation axis lines without any user-specified threshold, so that the proposed method is very straightforward, robust and efficient.

关键词： Vortex definition vortex identification flow visualization liutex liutex magnitude gradient vortex core lines

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Explicit formula for the liutex vector and physical meaning of vorticity based on the liutex-Shear decomposition

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Journal of Hydrodynamics 2019年第3期31卷 464-474页

作者： Yi-qian Wang Yi-sheng Gao jian-ming liu Chaoqun liu School of Aerospace Engineering Tsinghua University Beijing 100084 China Department of Mathematics University of Texas at Arlington Arlington 76019 Texas USA School of Mathematics and Statistics Jiangsu Normal University Xuzhou 221116 China

In the present study, the physical meaning of vorticity is revisited based on the liutex-Shear (RS) decomposition proposed by liu et al. in the framework of liutex (previously called Rortex), a vortex vector field with information of both rotation axis and swirling strength (liu et al. 2018). It is demonstrated that the vorticity in the direction of rotational axis is twice the spatial mean angular velocity in the small neighborhood around the considered point while the imaginary part of the complex eigenvalue (2c.) of the velocity gradient tensor (if exist) is the pseudo-time average angular velocity of a trajectory moving circularly or spirally around the axis. In addition, an explicit expression of the liutex vector in terms of the eigenvalues and eigenvectors of velocity gradient is obtained for the first time from above understanding, which can further, though mildly, accelerate the calculation and give more physical comprehension of the liutex vector.

关键词： Vorticity liutex liutex-Shear(RS)decomposition explicit formula of liutex

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Mathematical foundation of turbulence generation-From symmetric to asymmetric liutex

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Journal of Hydrodynamics 2019年第3期31卷 632-636页

作者： jian-ming liu Yue Deng Yi-sheng Gao Sita Charkrit Chaoqun liu School of Mathematics and Statistics Jiangsu Normal University Xuzhou 221116 China Department of Mathematics University of Texas at Arlington Arlington 76019 Texas USA Department of Physics University of Texas at Arlington Arlington 76019 Texas USA

Vortices have been regarded as the building blocks and muscles of turbulence for a long time. To better describe and analyze vortices or vortical structures, recently a new physical quantity called liutex (previously named Rortex) is introduced to present the rigid rotation part of fluid motion (liu et al. 2018). Since turbulence is closely related to the vortex, it can be postulated that there exists no turbulence without liutex. According to direct numerical simulations (DNS) and experiments, forest of hairpin vortices has been found in transitional and low Reynolds number turbulent flows, while one-leg vortices are predominant in full developed turbulent flows. This paper demonstrates that the hairpin vortex is unstable. The hairpin vortex will be weakened or lose one leg by the shear and liutex interaction, based on the liutex definition and mathematical analysis without any physical assumptions. The asymmetry of the vortex is caused by the interaction of symmetric shear and symmetric liutex since the smaller element of a pair of vorticity elements determines the rotational strength. For a 2-D fluid rotation, if a disturbance shear effects the larger element, the rotation strength will not be changed, but if the disturbance shear effects the smaller element, the rotation strength will be immediately changed due to the definition of the liutex strength. For a rigid rotation, if the shearing part of the vorticity and liutex present the same directions, e.g., clockwise, the liutex strength will not be changed. If the shearing part of the vorticity and liutex present different directions, e.g., one clockwise and another counterclockwise, the liutex strength will be weakened.Consequently, the hairpin vortex could lose the symmetry and even deform to a one-leg vortex. The one-leg vortex cannot keep balance, and the chaotic motion and flow fluctuation are doomed. This is considered as the mathematical foundation of turbulence formation. The DNS results of boundary layer transition are used to justify this theory.

关键词： Turbulence generation mathematical principle liutex/Rortex asymmetry

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Chinese Internet Searches Provide Inaccurate and Misleading Information to Epilepsy Patients

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Chinese Medical Journal 2015年第24期128卷 3324-3328页

作者： jian-ming liu Ru-Xiang Xu Yong-Sheng Hu Lian-Kun Ren Hui Qiao Hu Ding Zhi-Liang liu Affiliated Bayi Brain Hospital Bayi Clinical College Southern Medical University Beijing 100700 China Department of Function Neurosurgery Beijing Xuanwu Hospital Beijing 100053 China Department of Neurology China-Japan Friendship Hospital Beijing 100029 China Department of Neuroelectrophysiology Beijing Tiantan Hospital Beijing 100050 China

Background： Most patients with epilepsy want to learn as much as possible about the disease, and many have turned to the internet for information. Patients are likely to use information obtained from the internet to control their epilepsy, but little is known about the accuracy of this information. In this survey, we have assessed the feasibility and usability ofinternet-based interventions for the treatment of epilepsy. Methods： Data were collected from an internet search. Different search terms were used to obtain general information on epilepsy together with information about medication, types of epilepsy, treatment, women＇s health, and other information. The accuracy of the information was evaluated by a group of experts. Results： A total of 1320 web pages were assessed. The majority were websites related to health. A large number （80.2%） of web pages contained content related to the search term. A significant number of web pages 450/1058 （42.5%） claimed to provide information from a credible source： however, only 206/1058 （19.5%） of the information was accurate and complete; 326/1058 （30.8%） was accurate but incomplete; 328/1058 （31.0%） was correct but nonstandard, and 198/1058 （18.8%） was inaccurate. The authenticity of the information was not significantly different between the two search engines （x^2 = 0.009, P - 0.924）. No significant difference was observed in the information obtained from a specialist or nonspecialist source （x^2 = 7.538, P- 0.057）. There was also no correlation between the quality of the information and the priority （x^2 = 6.880, P = 0,076）. Conclusions： Searching for information about epilepsy on the internet is convenient, but the information provided is not reliable. Too much information is inaccurate or for advertisement purposes, and it is difficult for patients to find the useful information. Turning to the internet for medical knowledge may be harmful. Physicians should be aware that their patients may search for information on the internet and guide them to safe, reputable web

关键词： Epilepsy Health Information Internet Self-management

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Corrosion behaviour of NiCrFeAl-hBN seal coatings in oxidation environments at a high temperature

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Rare Metals 2021年第1期40卷 212-218页

作者： Su-Yuan Yang Dan Guo Xing-Wang Cheng jian-ming liu Yue-Guang Yu School of Materials Science and Engineering Beijing Institute of TechnologyBeijing 100081.China National Key Laboratory of Science and Technol Beijing General Research

The purpose of this investigation was to evaluate the microstructure,high-temperature oxidation behaviour,and hardness of a seal coating under controlled exposures at 750℃with different exposure times.The results reveal that the main phases in the coating are Ni,FeNi3,and hexagonal BN,withα-Al_(2)O_(3)peaks appearing after 2-h oxidation.As the exposure time increases,the diffraction peak intensity ofα-Al_(2)O_(3)begins to decrease and Cr_(2)O_(3)peaks appear after 200 h.After 1000 h,Cr_(2)O_(3)becomes dominant with only small amounts ofα-Al_(2)O_(3)remaining.The high-temperature oxidation process of the coating includes three stages:the fast stage,transition stage,and slow stage.The oxidation rate is constant in each stage,and in the fast stage and slow stages with values of7.9×10^(-4)and 8.37×10^(-5)mg^(2)·cm^(-4)·s^(-1),respectively.Initially,α-Al_(2)O_(3)forms near the pores in the coating,followed by the formation of Cr_(2)O_(3).As the exposure time increases,oxidation penetrates into the interior of the coating along phase boundaries to form island-shaped inner oxide layers with high concentrations of Cr,Ni,and Fe.Additionally,hardness increases with increasing oxide percentage.

关键词： NiCrFeAl-hBN Seal coating Oxidation Microstructure High temperature

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liutex theoretical system and six core elements of vortex identification

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Journal of Hydrodynamics 2020年第2期32卷 197-211页

作者： Yi-qian Wang Yi-sheng Gao Hongyi Xu Xiang-rui Dong jian-ming liu Wen-qian Xu Meng-long Chen Chaoqun liu School of Mathematical Science Soochow UniversitySuzhou215006China College of Aerospace Engineering Nanjing University of Aeronautics and AstronauticsNanjing210016China Aeronautics and Astronautics Department Fudan UniversityShanghai200433China School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai200093China School of Mathematics and Statistics Jiangsu Normal UniversityXuzhou221116China Faculty of Mechanical Engineering and Automation Zhejiang Sci-Tech UniversityHangzhou310018China SimpleHPC LTD. Shanghai200030China Department of Mathematics University of Texas at ArlingtonArlington76019USA

The third-generation vortex identification method of liutex(previously called Rortex)was introduced by the team led by Prof.Chaoqun liu from University of Texas at Arlington to mathematically extract the rigid rotation part from the fluid motion,and thus to define and visualize vortices.Unlike the vorticity-based first generation and the scalar-valued second generation,Q,λ2,Δandλci methods for example,the liutex vector provides a unique,mathematical and systematic way to define vortices and visualize vortical structures from multiple perspectives without ambiguity.In this article,we summarize the recent developments of the liutex framework and discuss the liutex theoretical system including its existence,uniqueness,stability,Galilean invariance,locality and globality,decomposition in tensor and vector forms,liutex similarity in turbulence,and multiple liutex-based vortex visualization methods including liutex lines,liutex magnitude iso-surfaces,liutex-Ωmethod,and liutex core line method,etc..Thereafter,the six core elements of vortex identification,including(1)absolute strength,(2)relative strength,(3)local rotational axis,(4)vortex rotation axes,(5)vortex core size,(6)vortex boundary,are used as touchstones against which the liutex vortex identification system is examined.It is demonstrated with illustrative examples that the liutex system is able to give complete and precise information of all six core elements in contrast to the failure and inaccuracy of the first and second-generation methods.The important concept that vorticity cannot represent vortex and the superiority of the liutex system over previous methods are reiterated and stated in appropriate places throughout the paper.Finally,the article concludes with future perspectives,especially the application of the liutex system in studying turbulence mechanisms encouraged by the discovery of liutex similarity law.As a newly defined physical quantity,liutex may open a door for quantified vortex and turbulence research including liutex(vortex)dynamics and

关键词： Vortex identification liutex vector six core elements liutex core line liutex similarity turbulence

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Journal of Hydrodynamics 2019年第6期31卷 1259-1262页

作者： Wen-qian Xu Yi-qian Wang Yi-sheng Gao jian-ming liu Hua-shu Dou Chaoqun liu Faculty of Mechanical Engineering and Automation Zhejiang Sci-Tech UniversityHangzhou 310018China Department of Mathematics University of Texas at ArlingtonArlington 76019USA School of Mathematical Science Soochow UniversitySuzhou 215006China College of Aerospace Engineering Nanjing university of Aeronautics and AstronauticsNanjing 210016China School of Mathematics and Statistics Jiangsu Normal UniversityXuzhou 221116China

Kolmogorov's 1941 theory(K41)of similarity hypotheses and the-5/3 law for energy spectrum are considered as the most important theoretical achievement in turbulence research and the success of the modem turbulence theory.The assumptions of sufficient high Reynolds number and isotropy of turbulence that K41 based upon,however,cannot generally be met in practice,and thus discrepancy is often observed between the f law and direct numerical simulation(DNS)results of boundary layers in wall bounded turbulence,especially for moderate to low Reynolds number flows.liutex vector is a recently defined new physical quantity which is extracted from turbulent flow to represent the rigid rotation part of fluid motion.Actually,liutex is free from viscous dissipation and thus independent of Reynolds number,relaxing the very high Reynold number assumption of K41.liutex similarity has been solidly demonstrated by DNS for a moderate Reynolds number turbulent boundary layer(Reθ≈1000),both the frequency and wavenumber spectrum of liutex accurately matches the-5/3 law,which is obviously much better than the turbulence energy spectrum,while vorticity and other popular vortex identification methods,Q criterion for example,do not possess such a distinguished feature due to stretching and shearing contamination.

关键词： -5/3 law liutex similarity K41 turbulent boundary layer moderate and low Reynolds number

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