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How will our knowledge of short gamma-ray bursts affect the distance measurement of binary neutron stars?

Science China(Physics,Mechanics & Astronomy) 2022年第1期65卷 103-118页

作者： Minghui Du Lixin Xu Institute of Theoretical Physics School of PhysicsDalian University of TechnologyDalian 116024China

Gravitational waves from binary neutron stars associated with short gamma-ray bursts have drawn considerable attention due to their prospect in cosmology.For such events,the sky locations of sources can be pinpointed with techniques such as identifying the host galaxies.However,the cosmological applications of these events still suffer from the problem of degeneracy between luminosity distance and inclination angle.To address this issue,a technique was proposed in previous study,i.e.,using the collimation property of short gamma-ray bursts.Based on the observations,we assume that the cosine of inclination follows a Gaussian distribution,which may act as a prior in the Bayes analysis to break the degeneracy.This paper investigates the effects of different Gaussian priors and detector configurations on distance measurement and cosmological research.We first derive a simplified Fisher information matrix for demonstration,and then conduct quantitative analyses via simulation.By varying the number of third-generation detectors and the scale of prior,we generate four catalogs of 1000 events.It is shown that,in the same detecting period,a network of detectors can recognize more and farther events than a single detector.Besides,adopting tighter prior and employing multiple detectors both decrease the error of luminosity distance.Also considered is the performance of a widely adopted formula in the error budget,which turns out to be a conservative choice in each case.As for cosmological applications,for theΛCDM model,500,200,600,and 300 events are required for the four configurations to achieve 1%H;accuracy.With all 1000 events in each catalog,H;and?;can be constrained to(0.66%,0.37%,0.76%,0.49%),and(0.010,0.006,0.013,0.010),respectively.The results of the Gaussian process also show that the gravitational wave standard siren can serve as a probe of cosmology at high redshifts.

关键词： gravitational wave binary neutron star short gamma-ray burst cosmology

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Advances in immune response to pulmonary infection:Nonspecificity,specificity and memory

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Chronic Diseases and Translational Medicine 2023年第2期9卷 71-81页

作者： Jianqiao xu lixin Xie College of Pulmonary&Critical Care Medicine 8th Medical CenterChinese PLA General HospitalBeijingChina Medical School of Chinese PLA BeijingChina

The lung immune response consists of various cells involved in both innate and adaptive immune processes.Innate immunity participates in immune resistance in a nonspecific manner,whereas adaptive immunity effectively eliminates pathogens through specific recognition.It was previously believed that adaptive immune memory plays a leading role during secondary infections;however,innate immunity is also involved in immune memory.Trained immunity refers to the long-term functional reprogramming of innate immune cells caused by the first infection,which alters the immune response during the second challenge.Tissue resilience limits the tissue damage caused by infection by controlling excessive inflammation and promoting tissue repair.In this review,we summarize the impact of host immunity on the pathophysiological processes of pulmonary infections and discuss the latest progress in this regard.In addition to the factors influencing pathogenic microorganisms,we emphasize the importance of the host response.

关键词： adaptive immunity innate immunity lung infection trained immunity

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考虑位置度误差的RV减速器多组滚针轴承动态载荷特性研究

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机械工程学报 2022年第17期58卷 144-155页

作者：许立新重庆大学机械与运载工程学院重庆400044 重庆大学机械传动国家重点实验室重庆400044

滚针轴承是制约RV减速器工作可靠性及其使用寿命的关键部件,为有效地揭示位置度误差对滚针轴承动态接触载荷变化及多组滚针轴承传力均载性能的影响规律,提出含位置度误差的多组滚针轴承-摆线针轮耦合传动机构动力学模型。该方法通过开... 详细信息

滚针轴承是制约RV减速器工作可靠性及其使用寿命的关键部件,为有效地揭示位置度误差对滚针轴承动态接触载荷变化及多组滚针轴承传力均载性能的影响规律,提出含位置度误差的多组滚针轴承-摆线针轮耦合传动机构动力学模型。该方法通过开展摆线针轮多点啮合接触分析,计算摆线针齿副法向接触载荷和切向摩擦载荷;通过开展滚针轴承动态接触分析,计算滚动体接触载荷及轴承转动副等效约束反力。在此基础上,提出摆线轮滚针轴承孔位置度误差表达方法,完成多组滚针轴承-摆线针轮耦合传动机构动力学模型组集。最后,以典型三曲轴RV80E减速器为对象,分析位置度误差对滚针轴承动态载荷分布规律及多组轴承传力均载特性的影响。研究表明,轴承滚动体接触载荷最大峰值可达其平均值的5.19倍,轴承载荷最大值和最小值分别是其平均值的1.60倍和0.21倍,载荷波动幅值差很大;随着位置度误差范围的放大,加工精度等级的降低,滚针轴承载荷平均值偏差增大,轴承之间偏载问题越突出。

关键词： RV减速器滚针轴承摆线传动动力学

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Application of an atmospheric pressure plasma jet in a rat model of ischaemic stroke:Design,optimisation,and characteristics

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High Voltage 2023年第2期8卷 315-325页

作者： Ye Chen Bingyan Yang Yuqing Liu Lixin Xu Zhongfang Shi Yixiao Liu Ruoyu Han Fang Yuan Jiting Ouyang xu Yan Kostya(Ken)Ostrikov Department of Pathophysiology Beijing Neurosurgical Institute/Beijing Tiantan HospitalCapital Medical UniversityBeijingChina School of Basic Medical Sciences Capital Medical UniversityBeijingChina School of Physics Beijing Institute of TechnologyBeijingChina School of Chemistry and Physics and Centre for Biomedical Technologies Queensland University of TechnologyBrisbaneQueenslandAustralia

Recent studies have shown the in vitro neuro-protective functions of atmospheric pressure plasma(APP)against multiple pathological injuries during ischaemic stroke(IS).However,whether APP treatment exerts a therapeutic effect on a rat IS model remains unclear.Here,on the basis of needle-to-ring dielectric barrier discharge,an atmospheric pressure plasma jet(APPJ)was designed,with the Helium as the working gas which was driven by a sinusoidal voltage.Then,the treatment conditions were optimised for IS rat model treatment and the characteristics of this APPJ were further diagnosed.Subsequently,the rat IS model was established through 90 min middle cerebral artery occlusion(MCAO),and plasma was intermittently inhaled by rats via the nasal cavity for a 2 min period at 60 min of MCAO process.The therapeutic effects of this plasma jet device were then evaluated using biomedical analyses.According to our results,intermittent APP inhalation in the MCAO rats increased the serum NO content,improved the neurological function,enhanced regional cerebral blood flow,lowered brain infarction,and reduced the cell apoptosis in brain tissues of MCAO rats.Collectively,our data provides a novel potential strategy for IS treatment by using atmospheric-pressure plasma inhalation.

关键词： needle cerebral MCAO treatment

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Suboptimal adaptive tracking control for FIR systems with binary-valued observations

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Science China(Information Sciences) 2021年第7期64卷 37-47页

作者： Xiangquan LI Zhengguang xu Jiarui CUI lixin ZHANG School of Automation and Electrical Engineering University of Science and Technology Beijing Key Laboratory of Knowledge Automation for Industrial Processes Ministry of Education

In this paper, we investigate and analyze the suboptimal adaptive control for finite impulse response(FIR) systems with binary-valued observations. As the parameters of FIR systems are unknown and the measurable observations can only provide limited information, we propose and analyze a two-segment design method of an adaptive control law. First, we divide the system running time axis into many sections;each of these sections is divided into two segments. During the short segment, we design the system inputs for estimating parameters. Thus, we employ the empirical-measure-based technique for designing the identification algorithm. Second, we introduce a tracking control law to track a given target based on the system parameter estimates obtained in the short segment. We achieve this using the certainty equivalent principle in the long segment. As the length of short segments tends to infinity, we observe that the parameter estimation algorithm is consistent. However, when the length of segments tends to infinity, we find that the adaptive tracking control law is asymptotically suboptimal. Finally, we demonstrate the efficiency of the two-segment design method using the simulation results.

关键词： parameter identification FIR systems binary-valued observations asymptotically suboptimal tracking adaptive control

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Concentration of mixed acid by electrodialysis for the intensification of absorption process in acrylic acid production

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Chinese Journal of Chemical Engineering 2021年第8期34卷 10-18页

作者： Hanxiao Du lixin Xie Jie Liu Shichang xu School of Chemical Engineering and Technology Tianjin UniversityTianjin 300072China Tianjin Key Laboratory of Membrane Science and Desalination Technology State Key Laboratory of Chemical EngineeringTianjin UniversityTianjin 300072China School of Chemical Engineering and Technology Hebei University of TechnologyTianjin 300130China Engineering Research Center of Seawater Utilization Ministry of EducationTianjin 300130China

The absorption process in acrylic acid production was water-intensive.The concentration of acrylic acid before distillation process was low,which induced to large amount of wastewater and enormous energy consumption.In this work,a new method was proposed to concentrate the side stream of absorption column and thus increase the concentration in bottom product by electrodialysis.The influence of operating conditions on concentration rate and specific energy consumption were investigated by a laboratory-scale device.When the voltage drop was 1 V·cP^(-1)(1 cP=10^(-3) Pa·s),flow velocity was 3 cm·s^(-1) and the temperature was 35℃,the concentration rates of acrylic acid and acetic acid could be 203.3%and 156.6%in the continual-ED process.Based on the experimental data,the absorption process combined with ED was simulated,in which the diluted solution from ED process was used as spray water and the concentrated solution was feed back to the absorption column.The results shown that the flow rate of spray water was decreased by 37.1%,and the acrylic acid concentration at the bottom of the tower was increased by 4.56%.The ions exchange membranes before and after use 1200 h were tested by membrane surface morphology(scanning electron microscope),membrane chemical groups(infrared spectra),ion exchange capacity,and membrane area resistance,which indicated the membrane were stable in the acid system.This method provides new method for energy conservation and emission reduction in the traditional chemical industry.

关键词： Acrylic acid production Electrodialysis Concentration Membranes Absorption Mixtures

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Distributed Adaptive Cooperative Tracking of Uncertain Nonlinear Fractional-order Multi-agent Systems

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IEEE/CAA Journal of Automatica Sinica 2020年第1期7卷 292-300页

作者： Zhitao Li lixin Gao Wenhai Chen Yu xu Institute of Intelligent Systems and Decision Wenzhou UniversityZhejiang 325035China College of Physics and Electronic Information Engineering Wenzhou UniversityWenzhou 325035China

In this paper, the leader-following tracking problem of fractional-order multi-agent systems is addressed. The dynamics of each agent may be heterogeneous and has unknown nonlinearities. By assumptions that the interaction topology is undirected and connected and the unknown nonlinear uncertain dynamics can be parameterized by a neural network, an adaptive learning law is proposed to deal with unknown nonlinear dynamics, based on which a kind of cooperative tracking protocols are constructed. The feedback gain matrix is obtained to solve an algebraic Riccati equation. To construct the fully distributed cooperative tracking protocols, the adaptive law is also adopted to adjust the coupling weight. With the developed control laws,we can prove that all signals in the closed-loop systems are guaranteed to be uniformly ultimately bounded. Finally, a simple simulation example is provided to illustrate the established result.

关键词： Index Terms—Adaptive control consensus distributed control,fractional-order systems multi-agent system.

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A systematic study on mycochemical profiles, antioxidant, and anti-inflammatory activities of 30 varieties of Jew’s ear(Auricularia auricula-judae)

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Food Science and Human Wellness 2022年第4期11卷 781-794页

作者： Tahidul Islam Fangjie Yao Wenyi Kang lixin Lu Baojun xu College of Horticulture Jilin Agricultural UniversityChangchun 130118China Food Science and Technology Program BNU-HKBU United International CollegeZhuhai 519087China National R&D Center for Edible Fungus Processing Technology Henan UniversityKaifeng 475004China

The health-promoting properties and chemical profiles of 30 Jew’s ear mushroom varieties were investigated. The antioxidant properties were determined by ferric reducing antioxidant power(FRAP), 1,1-diphenyl-2-picrylhydrazyl(DPPH) free radical scavenging, 2,2’-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS) free radical scavenging, and metal chelating ability(MCA) assays, while phenolic profiles were determined by total phenol content(TPC) and total flavonoid content(TFC) colorimetric assays. Total carbohydrate, β-glucan, and melanin contents were determined by colorimetric methods. 5’-Nucleotides, vitamin D_(2), ergosterol, and ergothioneine contents were determined by high performance liquid chromatography(HPLC). Anti-inflammation activities of Jew’s ear were evaluated by the colorimetric protease inhibitory method. The results showed that Jew’s ear mushrooms possessed substantial phenolics and antioxidant properties. All the Jew’s ear varieties contain high amount of total carbohydrate, β-glucan, reducing sugar, melanin, pectin, vitamin D2, ergosterol, and ergothioneine. The current findings could provide scientific information for breeders to nurture desired varieties and for food industry to develop new health promoting products.

关键词： Auricularia auricula-judae Phenolic compounds Antioxidant properties Chemical composition Anti-inflammation High performance liquid chromatography

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Dynamic characteristics analysis and flight control design for oblique wing aircraft

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Chinese Journal of Aeronautics 2016年第6期29卷 1664-1672页

作者： Wang lixin xu Zijian Yue Ting School of Aeronautics Science and Engineering Beihang University

The movement characteristics and control response of oblique wing aircraft(OWA) are highly coupled between the longitudinal and lateral-directional axes and present obvious nonlinearity. Only with the implementation of flight control systems can flying qualities be satisfied. This article investigates the dynamic modeling of an OWA and analyzes its dynamic characteristics.Furthermore, a flight control law based on model-reference dynamic inversion is designed and verified. Calculations and simulations show that OWA can be trimmed by rolling a bank angle and deflecting the triaxial control surfaces in a coordinated way. The oblique wing greatly affects longitudinal motion. The short-period mode is highly coupled between longitudinal and lateral motion,and the bank angle also occurs in phugoid mode. However, the effects of an oblique wing on lateral mode shape are relatively small. For inherent control characteristics, symmetric deflection of the horizontal tail will generate not only longitudinal motion but also a large rolling rate. Rolling moment and pitching moment caused by aileron deflection will reinforce motion coupling, but rudder deflection has relatively little effect on longitudinal motion. Closed-loop simulations demonstrate that the flight control law can achieve decoupling control for OWA and guarantee a satisfactory dynamic performance.

关键词： Control allocation Decoupling Dynamic characteristics Model-reference dynamic inversion Oblique wing aircraft

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Sliding mode control design for oblique wing aircraft in wing skewing process

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Chinese Journal of Aeronautics 2019年第2期32卷 263-271页

作者： Ting YUE Zijian xu lixin WANG Tong WANG School of Aeronautic Science and Engineering Beihang University China Ship Development and Design Center

When the wing of Oblique Wing Aircraft(OWA) is skewed, the center of gravity, inertia and aerodynamic characteristics of the aircraft all significantly change, causing an undesirable flight dynamic response, affecting the flying qualities, and even endangering the flight safety. In this study,the dynamic response of an OWA in the wing skewing process is simulated, showing that the threeaxis movements of the OWA are highly coupled and present nonlinear characteristics during the wing skewing. As the roll control efficiency of the aileron decreases due to the shortened control arm in an oblique configuration, the all-moving horizontal tail is used for additional roll and the control allocation is performed based on minimum control energy. Given the properties of pitchroll-yaw coupling and control input and state coupling, and the difficulty of establishing an accurate aerodynamic model in the wing skewing process due to unsteady aerodynamic force, a multi-loop sliding mode controller is formulated by the time-scale separation method. The closed-loop simulation results show that the asymmetric aerodynamics can be balanced and that the velocity and altitude of the aircraft maintain stable, which means that a smooth transition is obtained during the OWA's wing skewing.

关键词： Decoupling Dynamic response Oblique wing aircraft Sliding mode control Wing skewing process

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