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Nonlinear dynamic behavior of a flexible asymmetric aero-engine rotor system in maneuvering flight

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Chinese Journal of Aeronautics 2020年第10期33卷 2633-2648页

作者： Tian Gao Shuqian CAO Yongtao SUN Department of Mechanics Tianjin UniversityTianjin 300354China tianjin Key Laboratory of Nonlinear Dynamics and Control Tianjin 300354China National Demonstration Center for Experimental Mechanics Education Tianjin UniversityTianjin 300354China

Aero-engine rotor systems installed in aircraft are considered to have a base motion.In this paper,a flexible asymmetric rotor system is modeled considering the nonlinear supports of ball bearings and Squeeze Film Dampers(SFDs),and the dynamic characteristics of the rotor system under maneuvering flight are systematically studied.Effects of the translational accelerative motions,the angular motions and the pitching flight with combined translational and angular motions on nonlinear dynamic behavior of the rotor system are investigated.The results show that,due to the nonlinear coupled effects among the rotor,ball bearings and SFDs,within the first bending resonance region,responses of the rotor show obvious nonlinear characteristics such as bistable phenomenon,amplitude jumping phenomenon and non-synchronous vibration.Translational acceleration motion of the aircraft leads to axis offset of the rotor system and thus results in the reduction and the final disappearance of the bistable rotating speed region.The pitching angular motion mainly affects rotational vibration of the rotor system,and thus further induces their transverse vibrations.For the pitching flight with combined translational and angular motions,a critical flight parameter is found to correspond to the conversion of two steady responses of the rotor system,in which one response displays small amplitude and synchronous vibration,and the other shows large amplitude and non-synchronous vibration.

关键词： Aero-engine rotor system Ball bearings Maneuvering flight Nonlinear dynamics Squeeze film dampers

Non-hallucinogenic Psychedelic Analog Design:A Promising Direction for Depression Treatment

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Neuroscience Bulletin 2023年第1期39卷 170-172页

作者： Ya-Nan Yin tian-Ming gao State Key Laboratory of Organ Failure Research Key Laboratory of Mental Health of the Ministry of EducationGuangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired IntelligenceGuangdong Province Key Laboratory of Psychiatric DisordersDepartment of NeurobiologySchool of Basic Medical SciencesSouthern Medical UniversityGuangzhou510515China

Depression is the most common neuropsychiatric disorder,affecting 350million people worldwide;it has been a leading cause of suicide,causing serious harm to family members and consuming a large amount of social resources.The onset time of traditional antidepressants is usually 3-4 weeks,and there is no ameliorating effect in nearly one-third of patients with depression.

关键词： consuming patients Depression

Galacto-oligosaccharides improve barrier function and relieve colonic inflammation via modulating mucosa-associated microbiota composition in lipopolysaccharides-challenged piglets

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Journal of Animal Science and Biotechnology 2022年第1期13卷 240-255页

作者： Ren gao Shiyi tian Jing Wang Weiyun Zhu National Center for International Research on Animal Gut Nutrition Jiangsu Key Laboratory of Gastrointestinal Nutrition and Animal HealthNational Experimental Teaching Demonstration Center of Animal ScienceLaboratory of Gastrointestinal MicrobiologyCollege of Animal Science and TechnologyNanjing Agricultural UniversityNanjing 210095China

Background:Galacto-oligosaccharides(GOS)have been shown to modulate the intestinal microbiota of suckling piglets to exert beneficial effects on intestinal function.However,the modulation of intestinal microbiota and intestinal function by GOS in intestinal inflammation injury models has rarely been reported.In this study,we investigated the effects of GOS on the colonic mucosal microbiota composition,barrier function and inflammatory response of lipopolysaccharides(LPS)-challenged suckling piglets.Methods:A total of 18 newborn suckling piglets were divided into three groups,the CON group,the LPS-CON group and the LPS-GOS group.Piglets in the LPS-GOS group were orally fed with 1 g/kg body weight of GOS solution every day.On the d 14,piglets in the LPS-CON and LPS-GOS group were challenged intraperitoneally with LPS solution.All piglets were slaughtered 2 h after intraperitoneal injection and sampled.Results:We found that the colonic mucosa of LPS-challenged piglets was significantly injured and shedding,while the colonic mucosa of the LPS-GOS group piglets maintained its structure.Moreover,GOS significantly reduced the concentration of malondialdehyde(MDA)and the activity of reactive oxygen species(ROS)in the LPS-challenged suckling piglets,and significantly increased the activity of total antioxidant capacity(T-AOC).GOS significantly increased the relative abundance of norank_f_Muribaculaceae and Romboutsia,and significantly decreased the relative abundance of Alloprevotella,Campylobacter and Helicobacter in the colonic mucosa of LPS-challenged suckling piglets.In addition,GOS increased the concentrations of acetate,butyrate and total short chain fatty acids(SCFAs)in the colonic digesta of LPS-challenged suckling piglets.GOS significantly reduced the concentrations of interleukin 1β(IL-1β),interleukin 6(IL-6),tumor necrosis factor-α(TNF-α)and cluster of differentiation 14(CD14),and the relative mRNA expression of Toll-like receptor 4(TLR4)and myeloid differentiation primary response 88(MyD88)in the LPS-challenge

关键词： Barrier function Galacto-oligosaccharides Intestinal microbiota Lipopolysaccharides Suckling piglets

Associations of daily sedentary behavior,physical activity,and sleep with irritable bowel syndrome:A prospective analysis of 362,193 participants

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Journal of Sport and Health Science 2024年第1期13卷 72-80页

作者： Xu gao Sifan tian Ninghao Huang Gang Sun Tao Huang Department of Occupational and Environmental Health Sciences School of Public HealthPeking UniversityBeijing 100191China Department of Epidemiology and Biostatistics School of Public HealthPeking UniversityBeijing 100191China Department of Gastroenterology and Hepatology First Medical Center of People's Liberation Army General HospitalBeijing 100853China

Background:Irritable bowel syndrome(IBS)substantially affects quality of life and requires early prevention.This study aimed to elucidate the relationships between IBS and daily behaviors,including sedentary behavior(SB),physical activity(PA),and sleep.In particular,it seeks to identify healthy behaviors to reduce IBS risk,which previous studies have rarely addressed.Methods:Daily behaviors were retrieved from self-reported data of 362,193 eligible UK Biobank participants.Incident cases were determined by self-report or health care data according to RomeⅣcriteria.Results:A total of 345,388 participants were IBS-free at baseline,during a median follow-up of 8.45 years,19,885 incident IBS cases were recorded.When examined individually,SB and shorter(≤7 h/day)or longer(>7 h/day)sleep duration were each positively associated with increased IBS risk,and PA was associated with lower IBS risk.The isotemporal substitution model suggested that replacing SB with other activities could provide further protective effects against IBS risk.Among people sleeping≤7 h/day,replacing 1 h of SB with equivalent light PA,vigorous PA,or sleep was associated with 8.1%(95%confidence interval(95%CI):0.901-0.937),5.8%(95%CI:0.896-0.991),and 9.2%(95%CI:0.885-0.932)reduced IBS risk,respectively.For people sleeping>7 h/day,light and vigorous PA were associated with a 4.8%(95%CI:0.926-0.978)and a 12.0%(95%CI:0.815-0.949)lower IBS risk,respectively.These benefits were mostly independent of genetic risk for IBS.Conclusion:SB and unhealthy sleep duration are risk factors for IBS.A promising way to mitigate IBS risk for individuals sleeping≤7 h/day and for those sleeping>7 h/day appears to be by replacing SB with adequate sleep or vigorous PA,respectively,regardless of the genetic predisposition of IBS.

关键词： Irritable bowel syndrome Isotemporal substitution model Physical activity Sedentary behavior Sleep

On a novel tracking differentiator design based on iterative learning in a moving window

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Control Theory and Technology 2023年第1期21卷 46-55页

作者： Xiangyang Li Rafal Madonski Zhiqiang gao Senping tian Key Laboratory of Autonomous Systems and Network Control Ministry of EducationSchool of Automation Science and EngineeringSouth China University of TechnologyGuangzhou 510641China Energy and Electricity Research Center Jinan UniversityZhuhai 519070China Department of Electrical and Computer Science Cleveland State UniversityClevelandOH 44115USA

Differential signals are key in control engineering as they anticipate future behavior of process variables and therefore are critical in formulating control laws such as proportional-integral-derivative(PID).The practical challenge,however,is to extract such signals from noisy measurements and this difficulty is addressed first by J.Han in the form of linear and nonlinear tracking differentiator(TD).While improvements were made,TD did not completely resolve the conflict between the noise sensitivity and the accuracy and timeliness of the differentiation.The two approaches proposed in this paper start with the basic linear TD,but apply iterative learning mechanism to the historical data in a moving window(MW),to form two new iterative learning tracking differentiators(IL-TD):one is a parallel IL-TD using an iterative ladder network structure which is implementable in analog circuits;the other a serial IL-TD which is implementable digitally on any computer platform.Both algorithms are validated in simulations which show that the proposed two IL-TDs have better tracking differentiation and de-noise performance compared to the existing linear TD.

关键词： Tracking differentiator(TD) Iterative learning Iterative learning tracking differentiator(IL-TD) Active disturbance rejection control(ADRC)-Two-dimensional system(2-D system)

Stem and leaf traits as co-determinants of canopy water flux

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Plant Diversity 2019年第4期41卷 258-265页

作者： Jianguo gao Kai tian Department of Ecology College of Urban and Environmental SciencesKey Laboratory for Earth Surface Processes of the Ministry o f EducationPeking UniversityNo.5 Yiheyuan Road Haidian DistrictBeijing100871PR China School of Life Sciences Nanjing UniversityNanjing210023PR China Coastal Ecosystems Research Station of the Yangtze River Estuary Ministry of Education Key Laboratory for Biodiversity Science and Ecological EngineeringInstitute of Biodiversity ScienceFudan UniversityShanghai200438PR China Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems Chinese Academy o f SciencesSouth China Botanical GardenGuangzhou510650PR China

However,the empirical relationship between leaf stomata anatomy and canopy stomatal conductance(Gs)is surprisingly rare,thereby the underlying biological mechanisms of terrestrial water flux are not well elucidated.To gain further insight into these mechanisms,we reanalyzed the dataset of Gs previously reported by gao et al.(2015)using a quantile regression model.The results indicated that the reference Cs(Gsref.Gs at 1 kPa)was negatively correlated with wood density at each quantile,which confirmed previous data;however,Gsref was significantly correlated with stomatal density at the 0.6 quantile,i.e.,450 stomata mm-2.This highlighted the potential of using stomatal density as a trait to predict canopy water flux.A conceptual model of co-determinants of xylem and stomatal morphology suggests that these traits and their coordination may play a critical role in determining tree growth,physiological homeostatic response to environmental variables,water use efficiency,and drought resistance.

关键词： Gsref Quantile regression Stomatal density Water flux Wood density

The effects of cool materials,façade orientation,and morphological parameters on energy consumption at the residential neighborhood scale

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Building Simulation 2024年第4期17卷 525-542页

作者： Fusuo Xu Dongdong tian Zhi gao Jianshun Jensen Zhang Department of Mechanical and Aerospace Engineering Syracuse UniversitySyracuseNY13210USA School of Architecture and Urban Planning Nanjing University22 Hankou RoadNanjingJiangsu Province210093China

Building surface cool materials are novel materials that can reduce urban heat island intensity and decrease building energy consumption.This study investigated the impact of radiative properties of materials,façade orientation,and morphological parameters on energy consumption in six typical residential neighborhoods in Nanjing,China.The neighborhood energy consumption of 16 application schemes considering the façade orientation factor is compared to determine the best energy-saving scheme.Seasonal and annual energy-saving rates,savings in electricity costs,and the price ceiling for materials per unit area are analyzed.The results show that for low-rise buildings,using cool materials only on the roof can reduce the annual energy consumption by 1%.When cool or super cool materials are also used on the building façade,the annual energy saving rate can be up to 3.4%and 4.3%,respectively.Using cool materials on the south façade of buildings is not recommended due to significant heat loss in winter.Considering savings in electricity costs and the price ceiling for materials per unit area,the price of cool and super cool materials should be less than 3.0 and 3.7 RMB/m2,respectively,assuming a lifespan of eight years in Nanjing.

关键词： cool materials building energy saving neighborhood morphology façade orientation

Reflection and operationalization of the common but differentiated responsibilities and respective capabilities principle in the transparency framework under the international climate change regime

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Advances in Climate Change Research 2018年第4期9卷 253-263页

作者： WANG tian gao Xiang National Center for Climate Change Strategy and International Cooperation Ministry of Ecology and Environment Beijing 100038 China Energy Research Institute National Development and Reform Commission Beijing 100038 China

“Common but differentiated responsibilities and respective capabilities”(CBDRRC) is the most significant guiding principle in the international climate change regime, created by the United Nations Framework Convention on Climate Change in 1992 and inherited by the Paris Agreement 24 years later. This paper examines the operationalization of the CBDRRC principle in one of the cornerstone rules of the regimedits transparency provisions, both in existing practice under the convention and possible evolvement in negotiations under the Paris Agreement, from the perspectives of both international rule-making and domestic implementation. The authors have found a continuous enhancement of the transparency framework since the 1990s, and gradual consolidation of a bifurcated system between developed and developing countries into a common one. The authors argue that the transparency framework, as part of the procedural rules, should be designed to facilitate transparent information sharing in accordance with substantive commitments under international climate change laws. Thus, it indirectly reflects historical responsibilities for climate change, while the framework should also be designed as feasible and reflective of the respective capabilities of nations. Finally, the evolution of the transparency framework will aim to enact common and enhanced provisions while differentiating between developed and developing countries in the near term, and greater transparency-related capacity-building for developing countries.

关键词： International climate change law UNFCCC Paris agreement Transparency Common but differentiated responsibilities and respective capabilities principle

Early-life galacto-oligosaccharides supplementation alleviates the small intestinal oxidative stress and dysfunction of lipopolysaccharide-challenged suckling piglets

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Journal of Animal Science and Biotechnology 2022年第5期13卷 1543-1556页

作者： Shiyi tian Jue Wang Ren gao Jing Wang Weiyun Zhu Laboratory of Gastrointestinal Microbiology Jiangsu Key Laboratory of Gastrointestinal Nutrition and Animal HealthNational Center for International Research on Animal Gut NutritionNational Experimental Teaching Demonstration Center of Animal ScienceCollege of Animal Science and TechnologyNanjing Agricultural UniversityNanjing 210095China

Background:Galacto-oligosaccharides(GOS)are non-digestible food ingredients that promote the growth of beneficial bacteria in the gut.This study investigated the protective effect of the early-life GOS supplement on the piglets’gut function against the oxidative stress induced by lipopolysaccharide(LPS)-challenge.Methods:Eighteen neonatal piglets were assigned to three groups including CON,LPS and LPS+GOS groups.The piglets in CON group and LPS group received physiological saline,while those in LPS+GOS group received GOS solution for 13 d after birth.On d 14,the piglets in LPS group and LPS+GOS group were injected with LPS solutions,while the piglets in CON group were injected with the same volume of physiological saline.Results:The results showed that the early-life GOS supplement blocked the LPS-induced reactive oxygen species(ROS)secretion,malondialdehyde(MDA)production and the increase of pro-apoptotic factor expression.Meanwhile,the early-life GOS supplement improved the activities of antioxidant enzymes,disaccharidase enzymes activities,and digestive enzymes activities,and increased the mRNA abundance of the gene related to nutrient digestion and absorption and the relative protein expression of tight junction.The study also showed that the early-life GOS supplement improved the expression of Hemeoxygenase-1(HO-1)and NAD(P)H/quinone acceptor oxidoreductase-1(NQO-1),and activated the AMP-activated protein kinase(AMPK).Conclusions:These results suggested that GOS enhanced the gut function,reduced the ROS production and proapoptotic factors gene expression,and activated the AMPK signaling pathway in LPS-challenged piglets.

关键词： Early-life Galacto-oligosaccharides Lipopolysaccharide Oxidative stress Suckling piglets