Purpose–The study aims to build a high-precision longitudinal dynamics model for heavy-haul trains and validate it with line test data,present an optimization method for multi-stage cyclic brakes based on the model a...Purpose–The study aims to build a high-precision longitudinal dynamics model for heavy-haul trains and validate it with line test data,present an optimization method for multi-stage cyclic brakes based on the model and conduct a multi-objective detailed evaluation of the driver’s manipulation during cyclic braking.Design/methodology/approach–The high-precision longitudinal train dynamics model was established and verified by the cyclic braking test data of the 20,000 t heavy-haul combination train on the long and steep downgrade.Then the genetic algorithm is employed for optimization subsequent to decoupling multiple cyclic braking procedures,with due consideration of driver operation rules.For evaluation,key manipulation assessments in the scenario are prioritized,supplemented by multi-objective evaluation requirements,and the computational model is employed for detailed evaluation analysis.Findings–Based on the model,experimental data reveal that the probability of longitudinal force error being less than 64.6 kN is approximately 68%,95%for less than 129.2 kN and 99.7%for less than 193.8 kN.Upon optimizing manipulations during the cyclic braking,the maximum reduction in coupler force spans from 21%∼23.9%.Andtheevaluation scoresimply that a proper elevationof the releasingspeed favorssafety.A high electric braking force,although beneficial to some extent for energy-saving,is detrimental to reducing coupler force.Originality/value–The results will provide a theoretical basis and practical guidance for further ensuring the safety and energy-efficient operation of heavy haul trains on long downhill sections and improving the operational quality of heavy-haul trains.展开更多
Purpose–This study summarizes the overall situation of the resources of the national science and technology innovation platform in the railway industry,including the distribution of platform types,supporting institut...Purpose–This study summarizes the overall situation of the resources of the national science and technology innovation platform in the railway industry,including the distribution of platform types,supporting institutions,construction sites,professional fields,etc.,to provide a reference for the further improvement and optimization of the national science and technology innovation platform system in the railway industry.Design/methodology/approach–Through literature review,field investigation,expert consultation and other methods,this paper systematically investigates and analyzes the development status of the national science and technology innovation platform in the railway industry.Findings–Taking the national science and technology innovation platform of the railway industry as the research object,this paper investigates and analyzes the construction,development and distribution of the national science and technology innovation platform of railway industry over the years.And the National Engineering Research Center of High-speed Railway and Urban Rail Transit System Technology was taken as an example to introduce its operation effect.Originality/value–China Railway has made great development achievements,with the construction and development of national science and technology innovation platform in the railway industry.In recent years,a large number of national science and technology innovation platforms have been built in the railway industry,which play an important role in railway technological innovation,standard setting and commodification,and Railway Sciences provide strong support for railway technology development.展开更多
Cordyceps is treasured entomopathogenic fungi that have been used as antitumor,immunomodulating,antioxidant,and pro-sexual agent.Cordyceps,also called DongChongXiaCao in Chinese,Yartsa Gunbu(Tibetan),means winter worm...Cordyceps is treasured entomopathogenic fungi that have been used as antitumor,immunomodulating,antioxidant,and pro-sexual agent.Cordyceps,also called DongChongXiaCao in Chinese,Yartsa Gunbu(Tibetan),means winter worm-summer grass.Natural Cordyceps sinensis with parasitic hosts is difficult to be collected and the recent findings on its potential pharmacological functions,resulted in skyrocketing prices.Therefore,finding a mass-production method or an alternative for C.sinensis products is a top-priority task.In this review,we describe current status of Cordyceps research and its recent developments in Taiwan.The content and pharmacological activities of four major industrial species of Cordyceps(C.sinensis,Cordyceps militaris,Cordyceps cicadae and Cordyceps sobolifera)used in Taiwan,were reviewed.Moreover,we highlighted the effect of using different methods of fermentation and production on the morphology and chemical content of Cordyceps sp.Finally,we summarized the bottle-necks and challenges facing Cordyceps research as well as we proposed future road map for Cordyceps industry in Taiwan.展开更多
Precise and quantitative measurement of soot particle emission plays an essential role in accurately assessing the combustion performance of aero-engine combustors and infrared signature levels in aircraft exhausts.Am...Precise and quantitative measurement of soot particle emission plays an essential role in accurately assessing the combustion performance of aero-engine combustors and infrared signature levels in aircraft exhausts.Among various intrusive or non-intrusive approaches for soot diagnostics,Laser-Induced Incandescence(LⅡ)technique has been increasingly applied for soot concentration measurement in various combustion environments such as laminar flames and internal combustion engines due to its high spatial resolution and sensitivity.As for LⅡmeasurement in aero-engine combustors,however,it normally suffers from very limited optical accesses and often faces mandatory requirements of oblique imaging from a small backward angle.In this work,we demonstrate a Two-Color(2C)LⅡsystem that simultaneously captures LⅡsignal images at two distinct wavelengths using a Scheimpflug imaging configuration.A projective transformation algorithm and image overlapping procedures were employed to spatially correct the raw Scheimpflug LⅡimages.Performance validation of the developed 2C-Scheimpflug LⅡsystem was first conducted under specified conditions in a laminar C_(2)H_(4)/air McKenna flame.The obtained Soot Volume Fraction(SVF)level and its spatial distribution are in consistent with previous studies under identical flame conditions reported by other research groups.Finally,as a demonstration of engineering benchmark application,we applied the developed 2C-Scheimpflug LⅡsystem to measure SVF distribution in the cross-section plane perpendicular to the direction of flame propagation at the exhaust of a single-sector dual-swirl aero-engine model combustor.Transient soot production events were observed and characteristics of the SVF distribution were investigated.These experimental results suggest the feasibility of the 2C-Scheimpflug LⅡtechnique developed in this work for precise and quantitative measurements of soot concentration in practical environments.展开更多
In recent years, with the rapid development of large-scale distributed wireless sensor systems and micro-power devices, the disadvantages of traditional chemical battery power supply mode are becoming more and more ob...In recent years, with the rapid development of large-scale distributed wireless sensor systems and micro-power devices, the disadvantages of traditional chemical battery power supply mode are becoming more and more obvious. Piezoelectric energy collector has attracted wide attention because of its simple structure, no heating, no electromagnetic interference, environmental protection and easy miniaturization. Wind energy is a reproducible resource. Wind energy harvester based on piezoelectric intelligent material can be named piezoelectric wind energy harvesting which converts wind energy into electric power and will have great application prospect. To promote the development of piezoelectric wind energy harvesting technology, research statuses on piezoelectric wind energy harvesting technology are reviewed. The existing problem and development direction about piezoelectric wind energy harvester in the future are discussed. The study will be helpful for researchers engaged in piezoelectric wind energy harvesting.展开更多
Fluidic Thrust Vectoring(FTV)is used for the yaw attitude control of tailless flying wing,which can significantly improve stealth performance,maneuverability and lateral/heading maneuverability.The FTV control scheme ...Fluidic Thrust Vectoring(FTV)is used for the yaw attitude control of tailless flying wing,which can significantly improve stealth performance,maneuverability and lateral/heading maneuverability.The FTV control scheme of co-directional secondary flow was designed based on a 30 kgf thrust turbojet engine,an equivalent rudder deflection control variable of Mass Flow Combination(MFC)was proposed,and a control model was established to form a FTV control system scheme,which was integrated with the flight control system of a 100 kg tailless flying wing with medium aspect ratio to achieve closed-loop control of the yaw attitude based on FTV.The heading stability augmentation and maneuvering control characteristics and time response characteristics of tailless flying wing by FTV were quantitatively studied through virtual flight test in a wind tunnel at a wind speed of 35 m/s.The results show that the control strategy based on MFC achieves bidirectional continuous and stable control of thrust vector angle in a range of±11°,and the thrust vector angle varies monotonically with MFC;the co-directional FTV realizes bidirectional continuous and stable control of the yaw attitude of tailless flying wing,without longitudinal/lateral coupling moment.The increment of the maximum yawing moment coefficient is 0.0029,the maximum yaw rate is 7.55(°)/s,and the response time of the yaw rate of the vectoring nozzle actuated by the secondary flow is about 0.06 s,which satisfies the heading stability augmentation and maneuvering control response requirements of the aircraft with statically unstable heading,and provides new control means for the heading rudderless attitude control of tailless flying wing.展开更多
The stator of the maglev track plays a crucial role in the operation of the maglev system.Currently,the efficiency of maglev track inspection is limited by several factors,including the large span of elevated structur...The stator of the maglev track plays a crucial role in the operation of the maglev system.Currently,the efficiency of maglev track inspection is limited by several factors,including the large span of elevated structures,manual visual inspection,short inspection window times,and limited GPS positioning accuracy.To address these issues,this paper proposes a deep learning-based method for detecting and locating stator surface damage.This study establishes a maglev track stator surface image dataset,trains different object detection models,and compares their performance.Ultimately,YOLO and ByteTrack object tracking algorithms were chosen as the basic framework and enhanced to achieve automatic identification of high-speed maglev track stator surface damage images and track and count stator surface localization feature images.By matching the identified damaged images with their corresponding stator segment and beam segment sequence numbers,the location of the damage is pinpointed to the corresponding stator segment,enabling rapid and accurate identification and localization of complex damage to the maglev track stator surface.展开更多
Regenerative catalytic oxidizers(RCO)are widely used to remove volatile organic compounds(VOCs)due to their energy-saving and stability.In this study,a multi-component catalytic reaction model was constructed to numer...Regenerative catalytic oxidizers(RCO)are widely used to remove volatile organic compounds(VOCs)due to their energy-saving and stability.In this study,a multi-component catalytic reaction model was constructed to numerically investigate the reaction process of hydrocarbon-containing VOCs in RCO using computational fluid dynamics(CFD)simulation.To obtain the conversion characteristics of multi-component hydrocarbons,the effects of intake load,equivalence ratio,and the composition of multi-component hydrocarbons on the flow,heat transfer,and conversion rate of the reactor were analyzed.A feasibility study plan targeting the hard-to-convert components was also proposed.The results indicated that as the load increases,the conversion rates of the various components decrease,while the reaction rates increase.Moreover,increasing the flow velocity intensifies turbulence and enhances the collision frequency between the gas and the wall surfaces.This,in turn,amplifies the resistance effect of the porous medium.As the equivalence ratio of VOCs to oxygen increases,the oxygen-deficient condition leads to a decrease in the molecular weight of the hydrocarbons involved in the reaction.The reaction temperature also shows a downward trend.A comparative analysis of the catalytic combustion characteristics of multi-component VOCs and single-component gases reveals that adding ethane and propane can facilitate methane oxidation.展开更多
This study experimentally investigates complex wave structures and flow characteristics in a transonic free jet using two high-resolution optical diagnostics techniques:tomographic particle image velocimetry(Tomo-PIV)...This study experimentally investigates complex wave structures and flow characteristics in a transonic free jet using two high-resolution optical diagnostics techniques:tomographic particle image velocimetry(Tomo-PIV)and tomographic background oriented schlieren(Tomo-BOS).The measurements reveal three typical flow features in the jet:the potential core,shock cells,and shear layers.Notably,the shear layer displays significant velocity gradient variations across the lip line and plays a critical role in pressure regulation.The first invariant of the velocity gradient tensor,P,effectively characterizes local compressibility effects,facilitating the identification of key flow structures.In conjunction with-Q_(s)analysis,the results emphasize shear-driven deformation and the radial decay of wave intensity.Overall,the study demonstrates that current experimental techniques enable preliminary quantitative evaluation of transonic wave phenomena,providing valuable tools for the analysis of compressible flows.展开更多
Laser-induced aerosols,predominantly submicron in size,pose significant environmental and health risks during the decommissioning of nuclear reactors.This study experimentally investigated the removal of laser-generat...Laser-induced aerosols,predominantly submicron in size,pose significant environmental and health risks during the decommissioning of nuclear reactors.This study experimentally investigated the removal of laser-generated aerosol particles using a water spray system integrated with an innovative system for pre-injecting electrically charged mist in our facility.To simulate aerosol generation in reactor decommissioning,a high-power laser was used to irradiate various materials(including stainless steel,carbon steel,and concrete),generating aerosol particles that were agglomerated with injected water mist and subsequently scavenged by water spray.Experimental results demonstrate enhanced aerosol removal via aerosol-mist agglomeration,with charged mist significantly improving particle capture by increasing wettability and size.The average improvements for the stainless steel,carbon steel,and concrete were 40%,44%,and 21%,respectively.The results of experiments using charged mist with different polarities(both positive and negative)and different surface coatings reveal that the dominant polarity of aerosols varies with the irradiated materials,influenced by their crystal structure and electron emission properties.Notably,surface coatings such as ZrO_(2)and CeO_(2)were found to possibly alter aerosol charging characteristics,thereby affecting aerosol removal efficiency with charged mist configurations.The innovative aerosol-mist agglomeration approach shows promise in mitigating radiation exposure,ensuring environmental safety,and reducing contaminated water during reactor dismantling.This study contributes critical knowledge for the development of advanced aerosol management strategies for nuclear reactor decommissioning.The understanding obtained in this work is also expected to be useful for various environmental and chemical engineering applications such as gas decontamination,air purification,and pollution control.展开更多
To understand fundamental problems in hypersonic laminar-turbulent boundary layer transition for three-dimensional complex vehicles,a new standard model with typical lifting-body features has been proposed,named as hy...To understand fundamental problems in hypersonic laminar-turbulent boundary layer transition for three-dimensional complex vehicles,a new standard model with typical lifting-body features has been proposed,named as hypersonic transition research vehicle(HyTRV).The configuration of HyTRV is fully analytical,and details of the design process are discussed in this study.The transition characteristics for HyTRV are investigated using three combined methods,i.e.,theoretical analyses,numerical simulations,and wind tunnel experiments.Results show that the fully analytic parameterization design of HyTRV can satisfy the model simplification requirements from both numerical simulations and wind tunnel experiments.Meanwhile,the flow field of HyTRV reveals typical transition mechanisms in six relatively separated regions,including the streamwise vortex instability,crossflow instability,secondary instability,and attachment-line instability.Therefore,the proposed HyTRV model is valuable for fundamental researches in hypersonic boundary layer transition.展开更多
The impact of unstable supercooled water droplets suspended in the cloud on the solid will cause its surface to freeze,and the flight safety of the aircraft will be seriously affected when flying in this environment.A...The impact of unstable supercooled water droplets suspended in the cloud on the solid will cause its surface to freeze,and the flight safety of the aircraft will be seriously affected when flying in this environment.Aircraft icing protection system is an important device to reduce icing accidents and improve aircraft safety performance,which is of great significance to ensure flight safety.Based on the energy source,this paper proposes a general strategy for constructing an aircraft icing protection system,including Active Anti-icing and De-icing(AAD)system,Passive Antiicing and De-icing(PAD)system and Composite Anti-icing and De-icing(CAD)system.The principle,scope of application,advantages and disadvantages of aircraft anti-icing and de-icing technologies such as electric pulse de-icing,low-frequency piezoelectric de-icing,and hydrophobic material anti-icing are explored in detail,and the corresponding improvement measures are proposed.The future development of aircraft anti-icing and de-icing technology is prospected,and some new ideas are provided for the improvement of aircraft anti-icing and de-icing technology.展开更多
The availability of local feed resources in various seasons can contribute as essential sources of carbohydrate and protein which significantly impact rumen fermentation and the subsequent productivity of the ruminant...The availability of local feed resources in various seasons can contribute as essential sources of carbohydrate and protein which significantly impact rumen fermentation and the subsequent productivity of the ruminant.Recent developments,based on enriching protein in cassava chips,have yielded yeast fermented cassava chip protein（YEFECAP） providing up to 47.5% crude protein（CP）,which can be used to replace soybean meal.The use of fodder trees has been developed through the process of pelleting;Leucaena leucocephala leaf pellets（LLP）,mulberry leaf pellets（MUP） and mangosteen peel and/or garlic pellets,can be used as good sources of protein to supplement ruminant feeding.Apart from producing volatile fatty acids and microbial proteins,greenhouse gases such as methane are also produced in the rumen.Several methods have been used to reduce rumen methane.However,among many approaches,nutritional manipulation using feed formulation and feeding management,especially the use of plant extracts or plants containing secondary compounds（condensed tannins and saponins） and plant oils,has been reported.This approach could help todecrease rumen protozoa and methanogens and thus mitigate the production of methane.At present,more research concerning this burning issue-the role of livestock in global warming-warrants undertaking further research with regard to economic viability and practical feasibility.展开更多
Seawater desalination has been peoples fond dream since ancient times, the dream is now becoming a reality. This paper presents a brief development history of reverse osmosis. Much attention was paid to innovative dev...Seawater desalination has been peoples fond dream since ancient times, the dream is now becoming a reality. This paper presents a brief development history of reverse osmosis. Much attention was paid to innovative development in membranes, modules, equipments and applied technology, including asymmetric and composite membranes, spiral-wound element and hollow fiber module, energy recovery equipments and different technological processes. The extension of reverse osmosis, such as desalination, pre-concentration, integrated processes and nanofiltration, is also briefly mentioned.展开更多
The linearity of the traveling-wave tube is a very important characteristic for a modern communication system. To improve the linearity of the traveling-wave tube at no expense of the saturated output power and overal...The linearity of the traveling-wave tube is a very important characteristic for a modern communication system. To improve the linearity of the traveling-wave tube at no expense of the saturated output power and overall efficiency, a modified pitch profile combined with a small adjustment of operating parameters is proposed. The optimal design of the helix circuit is evaluated theoretically by a large signal analysis, and the experimental test is also carried out to make a comparison of performance between the novel and original designed traveling-wave tubes. The experiments show that the saturated output powers and efficiencies of these two tubes are close to each other, while the linearity of the traveling-wave tube is obviously improved. The total phase shift and AM/PM conversion at saturation of the novel tube, averaged over the operating band, are only 30.6°/d B and 2.5°/d B, respectively, which are 20.1°/d B and 1.6°/d B lower than those of the original tube, respectively. Moreover, the third-order intermodulation of the novel tube is up to 2.2 d Bc lower than that of the original tube.展开更多
Reverse transcription quantitative PCR (RT-qPCR) is a highly sensitive technique that has become the standard for the analysis of differences in gene expression in response to experimental treatments or among genetic ...Reverse transcription quantitative PCR (RT-qPCR) is a highly sensitive technique that has become the standard for the analysis of differences in gene expression in response to experimental treatments or among genetic sources. The accuracy of the RT-qPCR results can be significantly affected by uncontrolled sources of variation that can be accounted for normalization with so-called reference genes stably expressed under various conditions. In this study we assessed the stability of 21 reference gene candidates in crowns of two alfalfa cultivars (Apica and Evolution) exposed to various environmental conditions (cold, water stress and photoperiod) and from above ground biomass of the cultivar Orca sampled at three developmental stages (vegetative, full bloom and mature pods). Candidates were selected based on their previous identification in other plant species or their stable expression in a differential hybridization of alfalfa ESTs with cDNA from non-acclimated and cold-acclimated alfalfa. Genes encoding ubiquitin protein ligase 2a (UBL-2a), actin depolymerizing factor (ADF) and retention in endoplasmic reticulum 1 protein (Rer1) were the most stable across experimental conditions. Conversely β-actin (Act), α-tubulin (Tub) and glyce-raldehyde 3-phosphate dehydrogenase (GAPDH) frequently used as “housekeeping genes” in gene expression studies showed poor stability. No more than two reference genes were required to normalize the gene expression data under each condition. Normalization of the expression of genes of interest with unstable reference genes led to observations that were conflicting with those made with validated reference genes and that were in some cases inconsistent with the current knowledge of the trait. The reference genes identified in this study are strong candidates for normalization of gene expression in cultivated alfalfa.展开更多
Bitterness,one of the 5“basic tastes”,is usually undesired by humans.However,abundant literature reported that bitter fruits and vegetables have beneficial health effects due to their bitter contributors.This review...Bitterness,one of the 5“basic tastes”,is usually undesired by humans.However,abundant literature reported that bitter fruits and vegetables have beneficial health effects due to their bitter contributors.This review provided an updated overview of the main bitter contributors of typical bitter fruits and vegetables and their health benefits.The main bitter contributors,including phenolics,terpenoids,alkaloids,amino acids,nucleosides and purines,were summarized.The bioactivities and wide range of beneficial effects of them on anti-cancers,anti-inflammations,anti-microbes,neuroprotection,inhibiting chronic and acute injury in organs,as well as regulating behavior performance and metabolism were reported.Furthermore,not only did the bitter taste receptors(taste receptor type 2 family,T2Rs)show taste effects,but extra-oral T2Rs could also be activated by binding with bitter components,regulating physiological activities via modulating hormone secretion,immunity,metabolism,and cell proliferation.This review provided a new perspective on exploring and explaining the nutrition of bitter foods,revealing the relationship between the functions of bitter contributors from food and T2Rs.Future trends may focus on revealing the possibility of T2Rs being targets for the treatment of diseases,exploring the mechanism of T2Rs mediating the bioactivities,and making bitter foods more acceptable without getting rid of bitter contributors.展开更多
This paper presents the state of the art research and application of microgrid in China, and then introduces the major concerns for the development of microgrid. The research related to microgrid inChinaarose around 2...This paper presents the state of the art research and application of microgrid in China, and then introduces the major concerns for the development of microgrid. The research related to microgrid inChinaarose around 2004, focused on the connection of distributed energy resources (DERs) to grid and its influence on distribution network, and then followed the microgrid concept of Consortium for Electric Reliability Technology Solutions (CERTS). However, the microgrid inChinahas taken a more active path with the development of DER and the encouragement of the development of smart grid and resource and energy needing. Now, nearly every province inChinahas typical researches and applications of microgrid. Besides, there are already two major patterns in the development of microgrid, the institute-domi- nating research and the enterprise-dominating application. Research institutions likeTianjinUniversity, Hefei University of Technology, Xi’an Jiaotong University,InstituteofElectrical Engineering(ChineseAcademyof Sciences), etc., are leading the research on microgrid. The companies like State Grid Corporation of China (SGCC), China Southern Power Grid (CSPG), etc., have accomplished several demonstration projects of microgrid, and give a further boost to its application. At the end of the paper, according to the present situation of the development of microgrid inChina, the facing problems and the way to deal with it are put forward.展开更多
Purpose–High-speed maglev technology can address the issues of adhesion,friction,vibration and highspeed current collection in traditional wheel-rail systems,making it an important direction for the future developmen...Purpose–High-speed maglev technology can address the issues of adhesion,friction,vibration and highspeed current collection in traditional wheel-rail systems,making it an important direction for the future development of high-speed rail technology.Design/methodology/approach–This paper elaborates on the demand and significance of developing high-speed maglev technology worldwide and examines the current status and technological maturity of several major high-speed maglev systems globally.Findings–This paper summarizes the challenges in the development of high-speed maglev railways in China.Based on this analysis,it puts forward considerations for future research on high-speed maglev railways.Originality/value–This paper describes the development status and technical maturity of several major high-speed maglev systems in the world for the first time,summarizes the existing problems in the development of China’s high-speed maglev railway and on this basis,puts forward the thinking of the next research of China’s high-speed maglev railway.展开更多
An original 600MPa high aluminum dual phase steel had been successfully developed in this paper.The microstructure analysis showed that the microstructures of the steel mainly consist of ferrite and 16%martensite whic...An original 600MPa high aluminum dual phase steel had been successfully developed in this paper.The microstructure analysis showed that the microstructures of the steel mainly consist of ferrite and 16%martensite which distributed around the ferrite grain boundaries.TEM analysis demonstrated that there exist lots of high density dislocations in ferrite as well as an obvious twin-structure and some ribbon structures in martensite.The tensile test and the bake-hardening test showed that the steel delivers an excellent mechanical properties of R p0.2=350-390MPa,R m=620-660MPa,R p0.2/R m=0.55-0.65,A 80mm=25-29%,n=0.18-0.21 and an excellent bake-hardening property of BH 2=50-60MPa as well as an excellent of work-hardening(WH)property of WH=120MPa。The spot-welding test showed that this dual phase steel has a good welding adaptability.Own to the excellent formability,the steel has been successfully used in the production of some auto parts.展开更多
文摘Purpose–The study aims to build a high-precision longitudinal dynamics model for heavy-haul trains and validate it with line test data,present an optimization method for multi-stage cyclic brakes based on the model and conduct a multi-objective detailed evaluation of the driver’s manipulation during cyclic braking.Design/methodology/approach–The high-precision longitudinal train dynamics model was established and verified by the cyclic braking test data of the 20,000 t heavy-haul combination train on the long and steep downgrade.Then the genetic algorithm is employed for optimization subsequent to decoupling multiple cyclic braking procedures,with due consideration of driver operation rules.For evaluation,key manipulation assessments in the scenario are prioritized,supplemented by multi-objective evaluation requirements,and the computational model is employed for detailed evaluation analysis.Findings–Based on the model,experimental data reveal that the probability of longitudinal force error being less than 64.6 kN is approximately 68%,95%for less than 129.2 kN and 99.7%for less than 193.8 kN.Upon optimizing manipulations during the cyclic braking,the maximum reduction in coupler force spans from 21%∼23.9%.Andtheevaluation scoresimply that a proper elevationof the releasingspeed favorssafety.A high electric braking force,although beneficial to some extent for energy-saving,is detrimental to reducing coupler force.Originality/value–The results will provide a theoretical basis and practical guidance for further ensuring the safety and energy-efficient operation of heavy haul trains on long downhill sections and improving the operational quality of heavy-haul trains.
文摘Purpose–This study summarizes the overall situation of the resources of the national science and technology innovation platform in the railway industry,including the distribution of platform types,supporting institutions,construction sites,professional fields,etc.,to provide a reference for the further improvement and optimization of the national science and technology innovation platform system in the railway industry.Design/methodology/approach–Through literature review,field investigation,expert consultation and other methods,this paper systematically investigates and analyzes the development status of the national science and technology innovation platform in the railway industry.Findings–Taking the national science and technology innovation platform of the railway industry as the research object,this paper investigates and analyzes the construction,development and distribution of the national science and technology innovation platform of railway industry over the years.And the National Engineering Research Center of High-speed Railway and Urban Rail Transit System Technology was taken as an example to introduce its operation effect.Originality/value–China Railway has made great development achievements,with the construction and development of national science and technology innovation platform in the railway industry.In recent years,a large number of national science and technology innovation platforms have been built in the railway industry,which play an important role in railway technological innovation,standard setting and commodification,and Railway Sciences provide strong support for railway technology development.
文摘Cordyceps is treasured entomopathogenic fungi that have been used as antitumor,immunomodulating,antioxidant,and pro-sexual agent.Cordyceps,also called DongChongXiaCao in Chinese,Yartsa Gunbu(Tibetan),means winter worm-summer grass.Natural Cordyceps sinensis with parasitic hosts is difficult to be collected and the recent findings on its potential pharmacological functions,resulted in skyrocketing prices.Therefore,finding a mass-production method or an alternative for C.sinensis products is a top-priority task.In this review,we describe current status of Cordyceps research and its recent developments in Taiwan.The content and pharmacological activities of four major industrial species of Cordyceps(C.sinensis,Cordyceps militaris,Cordyceps cicadae and Cordyceps sobolifera)used in Taiwan,were reviewed.Moreover,we highlighted the effect of using different methods of fermentation and production on the morphology and chemical content of Cordyceps sp.Finally,we summarized the bottle-necks and challenges facing Cordyceps research as well as we proposed future road map for Cordyceps industry in Taiwan.
基金supported by the Equipment Test and Evaluation Technology Research Project,China(No.2100070017)the Natural Science Foundation of Gansu Province,China(No.24JRRA415)。
文摘Precise and quantitative measurement of soot particle emission plays an essential role in accurately assessing the combustion performance of aero-engine combustors and infrared signature levels in aircraft exhausts.Among various intrusive or non-intrusive approaches for soot diagnostics,Laser-Induced Incandescence(LⅡ)technique has been increasingly applied for soot concentration measurement in various combustion environments such as laminar flames and internal combustion engines due to its high spatial resolution and sensitivity.As for LⅡmeasurement in aero-engine combustors,however,it normally suffers from very limited optical accesses and often faces mandatory requirements of oblique imaging from a small backward angle.In this work,we demonstrate a Two-Color(2C)LⅡsystem that simultaneously captures LⅡsignal images at two distinct wavelengths using a Scheimpflug imaging configuration.A projective transformation algorithm and image overlapping procedures were employed to spatially correct the raw Scheimpflug LⅡimages.Performance validation of the developed 2C-Scheimpflug LⅡsystem was first conducted under specified conditions in a laminar C_(2)H_(4)/air McKenna flame.The obtained Soot Volume Fraction(SVF)level and its spatial distribution are in consistent with previous studies under identical flame conditions reported by other research groups.Finally,as a demonstration of engineering benchmark application,we applied the developed 2C-Scheimpflug LⅡsystem to measure SVF distribution in the cross-section plane perpendicular to the direction of flame propagation at the exhaust of a single-sector dual-swirl aero-engine model combustor.Transient soot production events were observed and characteristics of the SVF distribution were investigated.These experimental results suggest the feasibility of the 2C-Scheimpflug LⅡtechnique developed in this work for precise and quantitative measurements of soot concentration in practical environments.
文摘In recent years, with the rapid development of large-scale distributed wireless sensor systems and micro-power devices, the disadvantages of traditional chemical battery power supply mode are becoming more and more obvious. Piezoelectric energy collector has attracted wide attention because of its simple structure, no heating, no electromagnetic interference, environmental protection and easy miniaturization. Wind energy is a reproducible resource. Wind energy harvester based on piezoelectric intelligent material can be named piezoelectric wind energy harvesting which converts wind energy into electric power and will have great application prospect. To promote the development of piezoelectric wind energy harvesting technology, research statuses on piezoelectric wind energy harvesting technology are reviewed. The existing problem and development direction about piezoelectric wind energy harvester in the future are discussed. The study will be helpful for researchers engaged in piezoelectric wind energy harvesting.
文摘Fluidic Thrust Vectoring(FTV)is used for the yaw attitude control of tailless flying wing,which can significantly improve stealth performance,maneuverability and lateral/heading maneuverability.The FTV control scheme of co-directional secondary flow was designed based on a 30 kgf thrust turbojet engine,an equivalent rudder deflection control variable of Mass Flow Combination(MFC)was proposed,and a control model was established to form a FTV control system scheme,which was integrated with the flight control system of a 100 kg tailless flying wing with medium aspect ratio to achieve closed-loop control of the yaw attitude based on FTV.The heading stability augmentation and maneuvering control characteristics and time response characteristics of tailless flying wing by FTV were quantitatively studied through virtual flight test in a wind tunnel at a wind speed of 35 m/s.The results show that the control strategy based on MFC achieves bidirectional continuous and stable control of thrust vector angle in a range of±11°,and the thrust vector angle varies monotonically with MFC;the co-directional FTV realizes bidirectional continuous and stable control of the yaw attitude of tailless flying wing,without longitudinal/lateral coupling moment.The increment of the maximum yawing moment coefficient is 0.0029,the maximum yaw rate is 7.55(°)/s,and the response time of the yaw rate of the vectoring nozzle actuated by the secondary flow is about 0.06 s,which satisfies the heading stability augmentation and maneuvering control response requirements of the aircraft with statically unstable heading,and provides new control means for the heading rudderless attitude control of tailless flying wing.
基金supported in part by the National Natural Science Foundation of China under Grant 52432012in part by the Shanghai Science and Technology Project with 25ZR1402508。
文摘The stator of the maglev track plays a crucial role in the operation of the maglev system.Currently,the efficiency of maglev track inspection is limited by several factors,including the large span of elevated structures,manual visual inspection,short inspection window times,and limited GPS positioning accuracy.To address these issues,this paper proposes a deep learning-based method for detecting and locating stator surface damage.This study establishes a maglev track stator surface image dataset,trains different object detection models,and compares their performance.Ultimately,YOLO and ByteTrack object tracking algorithms were chosen as the basic framework and enhanced to achieve automatic identification of high-speed maglev track stator surface damage images and track and count stator surface localization feature images.By matching the identified damaged images with their corresponding stator segment and beam segment sequence numbers,the location of the damage is pinpointed to the corresponding stator segment,enabling rapid and accurate identification and localization of complex damage to the maglev track stator surface.
基金supported by National Key Research&Development Program of China(2022YFB4101500).
文摘Regenerative catalytic oxidizers(RCO)are widely used to remove volatile organic compounds(VOCs)due to their energy-saving and stability.In this study,a multi-component catalytic reaction model was constructed to numerically investigate the reaction process of hydrocarbon-containing VOCs in RCO using computational fluid dynamics(CFD)simulation.To obtain the conversion characteristics of multi-component hydrocarbons,the effects of intake load,equivalence ratio,and the composition of multi-component hydrocarbons on the flow,heat transfer,and conversion rate of the reactor were analyzed.A feasibility study plan targeting the hard-to-convert components was also proposed.The results indicated that as the load increases,the conversion rates of the various components decrease,while the reaction rates increase.Moreover,increasing the flow velocity intensifies turbulence and enhances the collision frequency between the gas and the wall surfaces.This,in turn,amplifies the resistance effect of the porous medium.As the equivalence ratio of VOCs to oxygen increases,the oxygen-deficient condition leads to a decrease in the molecular weight of the hydrocarbons involved in the reaction.The reaction temperature also shows a downward trend.A comparative analysis of the catalytic combustion characteristics of multi-component VOCs and single-component gases reveals that adding ethane and propane can facilitate methane oxidation.
文摘This study experimentally investigates complex wave structures and flow characteristics in a transonic free jet using two high-resolution optical diagnostics techniques:tomographic particle image velocimetry(Tomo-PIV)and tomographic background oriented schlieren(Tomo-BOS).The measurements reveal three typical flow features in the jet:the potential core,shock cells,and shear layers.Notably,the shear layer displays significant velocity gradient variations across the lip line and plays a critical role in pressure regulation.The first invariant of the velocity gradient tensor,P,effectively characterizes local compressibility effects,facilitating the identification of key flow structures.In conjunction with-Q_(s)analysis,the results emphasize shear-driven deformation and the radial decay of wave intensity.Overall,the study demonstrates that current experimental techniques enable preliminary quantitative evaluation of transonic wave phenomena,providing valuable tools for the analysis of compressible flows.
基金financial support from the Nuclear Energy Science&Technology and Human Resource Development Project of the Japan Atomic Energy Agency/Collaborative Laboratories for Advanced Decommissioning Science(No.R04I034)The author Ruicong Xu appreciates the scholarship(financial support)from the China Scholarship Council(CSC,No.202106380073).
文摘Laser-induced aerosols,predominantly submicron in size,pose significant environmental and health risks during the decommissioning of nuclear reactors.This study experimentally investigated the removal of laser-generated aerosol particles using a water spray system integrated with an innovative system for pre-injecting electrically charged mist in our facility.To simulate aerosol generation in reactor decommissioning,a high-power laser was used to irradiate various materials(including stainless steel,carbon steel,and concrete),generating aerosol particles that were agglomerated with injected water mist and subsequently scavenged by water spray.Experimental results demonstrate enhanced aerosol removal via aerosol-mist agglomeration,with charged mist significantly improving particle capture by increasing wettability and size.The average improvements for the stainless steel,carbon steel,and concrete were 40%,44%,and 21%,respectively.The results of experiments using charged mist with different polarities(both positive and negative)and different surface coatings reveal that the dominant polarity of aerosols varies with the irradiated materials,influenced by their crystal structure and electron emission properties.Notably,surface coatings such as ZrO_(2)and CeO_(2)were found to possibly alter aerosol charging characteristics,thereby affecting aerosol removal efficiency with charged mist configurations.The innovative aerosol-mist agglomeration approach shows promise in mitigating radiation exposure,ensuring environmental safety,and reducing contaminated water during reactor dismantling.This study contributes critical knowledge for the development of advanced aerosol management strategies for nuclear reactor decommissioning.The understanding obtained in this work is also expected to be useful for various environmental and chemical engineering applications such as gas decontamination,air purification,and pollution control.
基金This work was supported by the National Natural Science Foundation of China(Grant 11702315,92052301)the National Key Research and Development Program of China(Grant 2016YFA0401200).
文摘To understand fundamental problems in hypersonic laminar-turbulent boundary layer transition for three-dimensional complex vehicles,a new standard model with typical lifting-body features has been proposed,named as hypersonic transition research vehicle(HyTRV).The configuration of HyTRV is fully analytical,and details of the design process are discussed in this study.The transition characteristics for HyTRV are investigated using three combined methods,i.e.,theoretical analyses,numerical simulations,and wind tunnel experiments.Results show that the fully analytic parameterization design of HyTRV can satisfy the model simplification requirements from both numerical simulations and wind tunnel experiments.Meanwhile,the flow field of HyTRV reveals typical transition mechanisms in six relatively separated regions,including the streamwise vortex instability,crossflow instability,secondary instability,and attachment-line instability.Therefore,the proposed HyTRV model is valuable for fundamental researches in hypersonic boundary layer transition.
基金the Open Fund of Key Laboratory of Power Research of China and the National Natural Science Foundation of China(No.2018YFC0809500)the Sichuan Science and Technology Plan Project,China(No.23NSFSC1923)+2 种基金the Laboratory of Icing and Anti/De-icing of CARDC,China(No.IADL20220406)the Key R&D Special Projects in Henan Province,China(No.221111321000)the Basic Scientific Research Business Expenses of Central Universities,China(No.J2023-033)。
文摘The impact of unstable supercooled water droplets suspended in the cloud on the solid will cause its surface to freeze,and the flight safety of the aircraft will be seriously affected when flying in this environment.Aircraft icing protection system is an important device to reduce icing accidents and improve aircraft safety performance,which is of great significance to ensure flight safety.Based on the energy source,this paper proposes a general strategy for constructing an aircraft icing protection system,including Active Anti-icing and De-icing(AAD)system,Passive Antiicing and De-icing(PAD)system and Composite Anti-icing and De-icing(CAD)system.The principle,scope of application,advantages and disadvantages of aircraft anti-icing and de-icing technologies such as electric pulse de-icing,low-frequency piezoelectric de-icing,and hydrophobic material anti-icing are explored in detail,and the corresponding improvement measures are proposed.The future development of aircraft anti-icing and de-icing technology is prospected,and some new ideas are provided for the improvement of aircraft anti-icing and de-icing technology.
文摘The availability of local feed resources in various seasons can contribute as essential sources of carbohydrate and protein which significantly impact rumen fermentation and the subsequent productivity of the ruminant.Recent developments,based on enriching protein in cassava chips,have yielded yeast fermented cassava chip protein（YEFECAP） providing up to 47.5% crude protein（CP）,which can be used to replace soybean meal.The use of fodder trees has been developed through the process of pelleting;Leucaena leucocephala leaf pellets（LLP）,mulberry leaf pellets（MUP） and mangosteen peel and/or garlic pellets,can be used as good sources of protein to supplement ruminant feeding.Apart from producing volatile fatty acids and microbial proteins,greenhouse gases such as methane are also produced in the rumen.Several methods have been used to reduce rumen methane.However,among many approaches,nutritional manipulation using feed formulation and feeding management,especially the use of plant extracts or plants containing secondary compounds（condensed tannins and saponins） and plant oils,has been reported.This approach could help todecrease rumen protozoa and methanogens and thus mitigate the production of methane.At present,more research concerning this burning issue-the role of livestock in global warming-warrants undertaking further research with regard to economic viability and practical feasibility.
文摘Seawater desalination has been peoples fond dream since ancient times, the dream is now becoming a reality. This paper presents a brief development history of reverse osmosis. Much attention was paid to innovative development in membranes, modules, equipments and applied technology, including asymmetric and composite membranes, spiral-wound element and hollow fiber module, energy recovery equipments and different technological processes. The extension of reverse osmosis, such as desalination, pre-concentration, integrated processes and nanofiltration, is also briefly mentioned.
基金Project supported by the National Natural Science Foundation of China(Grant No.61401430)
文摘The linearity of the traveling-wave tube is a very important characteristic for a modern communication system. To improve the linearity of the traveling-wave tube at no expense of the saturated output power and overall efficiency, a modified pitch profile combined with a small adjustment of operating parameters is proposed. The optimal design of the helix circuit is evaluated theoretically by a large signal analysis, and the experimental test is also carried out to make a comparison of performance between the novel and original designed traveling-wave tubes. The experiments show that the saturated output powers and efficiencies of these two tubes are close to each other, while the linearity of the traveling-wave tube is obviously improved. The total phase shift and AM/PM conversion at saturation of the novel tube, averaged over the operating band, are only 30.6°/d B and 2.5°/d B, respectively, which are 20.1°/d B and 1.6°/d B lower than those of the original tube, respectively. Moreover, the third-order intermodulation of the novel tube is up to 2.2 d Bc lower than that of the original tube.
文摘Reverse transcription quantitative PCR (RT-qPCR) is a highly sensitive technique that has become the standard for the analysis of differences in gene expression in response to experimental treatments or among genetic sources. The accuracy of the RT-qPCR results can be significantly affected by uncontrolled sources of variation that can be accounted for normalization with so-called reference genes stably expressed under various conditions. In this study we assessed the stability of 21 reference gene candidates in crowns of two alfalfa cultivars (Apica and Evolution) exposed to various environmental conditions (cold, water stress and photoperiod) and from above ground biomass of the cultivar Orca sampled at three developmental stages (vegetative, full bloom and mature pods). Candidates were selected based on their previous identification in other plant species or their stable expression in a differential hybridization of alfalfa ESTs with cDNA from non-acclimated and cold-acclimated alfalfa. Genes encoding ubiquitin protein ligase 2a (UBL-2a), actin depolymerizing factor (ADF) and retention in endoplasmic reticulum 1 protein (Rer1) were the most stable across experimental conditions. Conversely β-actin (Act), α-tubulin (Tub) and glyce-raldehyde 3-phosphate dehydrogenase (GAPDH) frequently used as “housekeeping genes” in gene expression studies showed poor stability. No more than two reference genes were required to normalize the gene expression data under each condition. Normalization of the expression of genes of interest with unstable reference genes led to observations that were conflicting with those made with validated reference genes and that were in some cases inconsistent with the current knowledge of the trait. The reference genes identified in this study are strong candidates for normalization of gene expression in cultivated alfalfa.
基金the financial support provided by“Pioneer”and“Leading Goose”R&D Program of Zhejiang(2022C020122022C02078)。
文摘Bitterness,one of the 5“basic tastes”,is usually undesired by humans.However,abundant literature reported that bitter fruits and vegetables have beneficial health effects due to their bitter contributors.This review provided an updated overview of the main bitter contributors of typical bitter fruits and vegetables and their health benefits.The main bitter contributors,including phenolics,terpenoids,alkaloids,amino acids,nucleosides and purines,were summarized.The bioactivities and wide range of beneficial effects of them on anti-cancers,anti-inflammations,anti-microbes,neuroprotection,inhibiting chronic and acute injury in organs,as well as regulating behavior performance and metabolism were reported.Furthermore,not only did the bitter taste receptors(taste receptor type 2 family,T2Rs)show taste effects,but extra-oral T2Rs could also be activated by binding with bitter components,regulating physiological activities via modulating hormone secretion,immunity,metabolism,and cell proliferation.This review provided a new perspective on exploring and explaining the nutrition of bitter foods,revealing the relationship between the functions of bitter contributors from food and T2Rs.Future trends may focus on revealing the possibility of T2Rs being targets for the treatment of diseases,exploring the mechanism of T2Rs mediating the bioactivities,and making bitter foods more acceptable without getting rid of bitter contributors.
文摘This paper presents the state of the art research and application of microgrid in China, and then introduces the major concerns for the development of microgrid. The research related to microgrid inChinaarose around 2004, focused on the connection of distributed energy resources (DERs) to grid and its influence on distribution network, and then followed the microgrid concept of Consortium for Electric Reliability Technology Solutions (CERTS). However, the microgrid inChinahas taken a more active path with the development of DER and the encouragement of the development of smart grid and resource and energy needing. Now, nearly every province inChinahas typical researches and applications of microgrid. Besides, there are already two major patterns in the development of microgrid, the institute-domi- nating research and the enterprise-dominating application. Research institutions likeTianjinUniversity, Hefei University of Technology, Xi’an Jiaotong University,InstituteofElectrical Engineering(ChineseAcademyof Sciences), etc., are leading the research on microgrid. The companies like State Grid Corporation of China (SGCC), China Southern Power Grid (CSPG), etc., have accomplished several demonstration projects of microgrid, and give a further boost to its application. At the end of the paper, according to the present situation of the development of microgrid inChina, the facing problems and the way to deal with it are put forward.
基金This paper was supported by the funding of Strategic research and consulting project of Chinese Academy of Engineering(Grant No.2022-XBZD-20).
文摘Purpose–High-speed maglev technology can address the issues of adhesion,friction,vibration and highspeed current collection in traditional wheel-rail systems,making it an important direction for the future development of high-speed rail technology.Design/methodology/approach–This paper elaborates on the demand and significance of developing high-speed maglev technology worldwide and examines the current status and technological maturity of several major high-speed maglev systems globally.Findings–This paper summarizes the challenges in the development of high-speed maglev railways in China.Based on this analysis,it puts forward considerations for future research on high-speed maglev railways.Originality/value–This paper describes the development status and technical maturity of several major high-speed maglev systems in the world for the first time,summarizes the existing problems in the development of China’s high-speed maglev railway and on this basis,puts forward the thinking of the next research of China’s high-speed maglev railway.
文摘An original 600MPa high aluminum dual phase steel had been successfully developed in this paper.The microstructure analysis showed that the microstructures of the steel mainly consist of ferrite and 16%martensite which distributed around the ferrite grain boundaries.TEM analysis demonstrated that there exist lots of high density dislocations in ferrite as well as an obvious twin-structure and some ribbon structures in martensite.The tensile test and the bake-hardening test showed that the steel delivers an excellent mechanical properties of R p0.2=350-390MPa,R m=620-660MPa,R p0.2/R m=0.55-0.65,A 80mm=25-29%,n=0.18-0.21 and an excellent bake-hardening property of BH 2=50-60MPa as well as an excellent of work-hardening(WH)property of WH=120MPa。The spot-welding test showed that this dual phase steel has a good welding adaptability.Own to the excellent formability,the steel has been successfully used in the production of some auto parts.
