Aircraft passengers are more and demanding in terms of thermal comfort. But it is not yet easy for aircraft crew to control the environment control system （ECS） that satisfies the thermal comfort for most passengers...Aircraft passengers are more and demanding in terms of thermal comfort. But it is not yet easy for aircraft crew to control the environment control system （ECS） that satisfies the thermal comfort for most passengers due to a number of causes. This paper adopts a corrected predicted mean vote （PMV） model and an adaptive model to assess the thermal comfort conditions for 31 investigated flights and draws the conclusion that there does exist an uncomfortable thermal phe- nomenon in civil aircraft cabins, especially in some short-haul continental flights. It is necessary to develop an easy way to predict the thermal sensation of passengers and to direct the crew to con- trol ECS. Due to the assessment consistency of the corrected PMV model and the adaptive model, the adaptive model of thermal neutrality temperature can be used as a method to predict the cabin optimal operative temperature. Because only the mean outdoor effective temperature ET＊ of a departure city is an input variable for the adaptive model, this method can be easily understood and implemented by the crew and can satisfy 80-90% of the thermal acceptability levels of passen- gers.展开更多
The emergence of the novel coronavirus has led to a global pandemic which has led to the airline industry facing severe losses. For air travel to recover, airlines need to ensure safe air travel. In this paper, the au...The emergence of the novel coronavirus has led to a global pandemic which has led to the airline industry facing severe losses. For air travel to recover, airlines need to ensure safe air travel. In this paper, the authors have modeled droplet dispersion after a single breath from an index patient. Computational Fluid Dynamics (CFD) simulations are conducted using the k-ωSST turbulence model in ANSYS Fluent. The authors have taken into consideration several parameters such as the size of the mouth opening, the velocity of the cabin air as well as the number of droplets being exhaled by the index patient to ensure a realistic simulation. Preliminary results indicate that after a duration of 20 s, droplets from the index patient disperse within a 10 m2 cabin area. About 75% of the droplets are found disperse for up to 2 m axially behind the index patient. This could possess an enhanced risk to passengers sitting behind the index patient. Ultimately, this paper provides an insight into the potential of CFD to visualise droplet dispersal and give impetus to ensure that necessary mitigating measures can be taken to reduce the risk of infection through droplet dispersal.展开更多
Abstract Air distribution in commercial airliner cabins is very important for the comfort and health of passengers and crew. Experimental measurements, computational fluid dynamics （CFD） simulations, and inverse mod...Abstract Air distribution in commercial airliner cabins is very important for the comfort and health of passengers and crew. Experimental measurements, computational fluid dynamics （CFD） simulations, and inverse modeling are state-of-the-art methods available for studying the air distri- bution. This paper gave an overview of the different experimental models, such as scale models, simplified models, full-scale mockups, and actual air cabins. Although experimental measurements were expensive and time consuming, the data were essential for validating CFD simulations. Different modeling strategies for CFD simulations were also discussed in this paper, including large eddy simulations and Reynolds averaged Navier-Stokes equation modeling. CFD simulations were main stream approaches for studying the air distribution but they could not easily lead to optimal design. Inverse modeling of air distribution has recently emerged into a very powerful and attractive tool for designing the air distribution in airliner cabins, although most of the studies were preliminary.展开更多
The vibration and noise produced by the powertrain and waves inside ship cabins limit working efficiency and crew and passengers’accommodation quality.This paper simplifies ship cabins as cavities and explores active...The vibration and noise produced by the powertrain and waves inside ship cabins limit working efficiency and crew and passengers’accommodation quality.This paper simplifies ship cabins as cavities and explores active control techniques to attenuate sound transmission via multiple parallel-supported flexible subplates.The theoretical formulations of the interaction between multiple subplates and cavities were performed and the coupling relationships between them were analyzed.Based on the multiple subplates and the cavity coupling models,numerical simulations were performed using the derived optimal controller to minimize the transmission of sound into the cavities through two and nine parallel-supported subplates.The various control strategies were explored to minimize the coupling system’s acoustic potential energy,and the control performances were compared and discussed.The mechanism of reducing sound transmission through multiple supported subplates into a cavity is revealed.The simulation results showed that the vibration pattern of the controlled subplate is changed after it is regulated,which increases its radiation to subdue the other subplates’radiation,while increasing vibration of the controlled subplate.The more subplates a cavity has,the more kinetic energy the controlled subplate possess.Furthermore,the noise reduction performance of a cavity with fewer subplates is better than that with more subplates.展开更多
The research of the ergonomic parameters of two tested forwarders was based on the measurement of a variability of physiological functions of the operator during one work shift. The research included a series of six m...The research of the ergonomic parameters of two tested forwarders was based on the measurement of a variability of physiological functions of the operator during one work shift. The research included a series of six measurements, each lasting l h and starting at 5：00, 12：00 and 17：00 O＇clock. The measured operator was at all times the same person. We had a hypothesis that the rate of the measured variability would have to do with the following four factors： forwarder cabin type, terrain character, fatigue during the work shift and work at daylight or in dark. Main findings are described below： during his work with a fixed type of the forwarder cab, the operator＇s brain waves at the frequency of Gamma, high Beta, Beta and Alpha reached statistically significantly higher average values than during his work with a rotating cab. With a higher degree of terrain roughness and in the forwarder with the rotating cab, the operator showed a significantly higher frequency and lower amplitude of respiration. At the beginning of the work shift, the tension of muscles in the operator＇s neck was at the significantly lowest level. In the afternoon, at the end of the work shift, the level of muscle tension was the highest. The “daylight/dark” work had a significantly highest impact on volume changes in the amplitude （strength） of blood pulse and on the skin conductance level. All research factors explained together 15%-65% of the variability of physiological functions.展开更多
Seoul metropolitan subway network is known to be the one of the most heavily used transportation means in the world. The subway cabins are naturally ventilated when the cabin doors are opened and through the gaps caus...Seoul metropolitan subway network is known to be the one of the most heavily used transportation means in the world. The subway cabins are naturally ventilated when the cabin doors are opened and through the gaps caused by the incomplete air-tightening of cabin bodies. Although, subway trains are equipped with a mechanical exhaust fan, the apparatus is rarely operated due to the problem of heating/cooling efficiency especially in the summer and winter seasons. In this study, we analyzed the transient CO2 （carbon dioxide） concentration level during the journey of a subway cabin when a heavy load of passengers of up to 200% of designed capacity using a CFD （computational fluid dynamics） analysis. With an increased journey time, the CO2 concentration increased by up to 5,000 ppm depending on passenger load. Through the operation of a mechanical exhaust fan, the high concentration of CO2 decreased down to 1,500 ppm. The effect of the exhaust fan operating on the dilution of indoor air was estimated by comparison with a closed cabin. In addition, the energy consumption for cooling in summer time was assessed for exhaust fan operations.展开更多
Air pollution induces significant health risks to individuals exposed to high levels of pollutants concentration. For ground vehicles, pollutants infiltrate the car cabin through the ventilation system, leading to pot...Air pollution induces significant health risks to individuals exposed to high levels of pollutants concentration. For ground vehicles, pollutants infiltrate the car cabin through the ventilation system, leading to potential health issues. To address this problem, a project was undertaken to develop a protocol for characterizing in-cabin air quality. The study involved a closed chamber (the bubble) where its internal multiphase flow has been optimized to create controlled polluted atmospheres. Experiments were conducted to optimize the positioning of the stirring fan and particle generation source, ensuring a homogeneous distribution of fine and ultrafine particles. This study demonstrated the feasibility of implementing a platform dedicated to characterizing the vehicles’ in-cabin air quality under controlled conditions. It allows a better understanding of the dynamics of particle infiltration and the establishment of an optimized protocol for simultaneous measurements of indoor and outdoor concentrations.展开更多
With projections indicating an increase in mobility over the next few decades andannual flight departures expected to rise to over 16 billion by 2050,there is a demand for theaviation industry and associated stakehold...With projections indicating an increase in mobility over the next few decades andannual flight departures expected to rise to over 16 billion by 2050,there is a demand for theaviation industry and associated stakeholders to consider new forms of aircraft and technology.Customer requirements are recognized as a key driver in business.The airline is the principalcustomer for the aircraft manufacture.The passenger is,in turn,the airline's principal customerbut they are just one of several stakeholders that include aviation authorities,airport operators,air-traffic control and security agencies.The passenger experience is a key differentiator usedby airlines to attract and retain custom and the fuselage that defines the cabin envelope for thein-flight passenger experience and cabin design therefore receives significant attention for newaircraft,service updates and refurbishments.Decision making in design is crucial to arrivingat viable and worthwhile cabin formats.Too litle innovation will result in an aircraftmanufacturer and airlines using its products falling behind its competitors.Too much mayresult in an over-extension with,for example,use of immature technologies that do not havethe necessary reliability for a safety critical industry or sufficient value to justify the develop-ment effort.The multiple requirements associated with cabin design,can be viewed as an area for optimisation,accepting trade-offs between the various parameters.Good design,however,is often defined as developing a concept that resolves the contradictions and takes the solutiontowards a win-win scenario.Indeed our understanding and practice of design allows forbehaviors that enhance design thinking through divergence and convergence,the use ofabductive reasoning,experimentation and systems thinking.This paper explores and definesthe challenges of designing the aireraft cabin of the future that will deliver on the multiplerequirements using experiences from the A350 XWB and future cabin design concepts.Inparticular the paper explores the value of implementing design thinking insights in engineeringpractice and discusses the relative merits of decisions based on optimisation versus win-winscenarios for aircraft cabin design and wider applications in aerospace environments.Theincreasing densification of technological opportunities and shifting consumer demand coupledwith highly complex systems may ultimately challenge our ability to make decisions based onoptimisation balances.From an engineering design perspective optimisation tends to precludecertain strategies that deliver high quality results in consumer scenarios whereas win-winsolutions may face challenges in complex technical environments.展开更多
The purpose of this study was to develop and evaluate a visibility evaluation system for the cabin type Far-East combine harvester.The human field of view has been classified into five levels(perceptive,effective,stab...The purpose of this study was to develop and evaluate a visibility evaluation system for the cabin type Far-East combine harvester.The human field of view has been classified into five levels(perceptive,effective,stable gaze,induced,and auxiliary)depending on the rotation of the human head and eye.The divider,reaper lever,gearshift,dashboard,and conveying component were considered as major viewpoints of the cabin type Far-East combine harvester.The visibility of the cabin type Far-East combine harvester was evaluated quantitatively using viewpoints and human field of view levels.The visibility evaluation system for the cabin type Far-East combine harvester consisted of a laser pointer,stepping motors to control the directions of the view,gyro sensors to measure horizontal and vertical angles,and I/O interface to acquire the signals.The visibility evaluation tests were conducted at different postures(‘sitting straight’,‘sitting with a 15°tilt’,‘standing straight’,and‘standing with a 15°tilt’)for three cabin type Far-East combine harvesters.The LSD(least significant difference)multiple comparison tests showed that the visibilities of viewpoints differed significantly as the operator's posture changed.The results showed that the posture while standing with a 15°tilt provided the best visibility.The average visibility scores at sitting postures were 22.3(straight)and 24.4(15°tilt),and the scores at standing postures were 18.7(straight)and 29.5(15°tilt).Also,the average visibility scores were observed in order from highest to lowest as reaper lever(44.6),divider(28.7),dashboard(23.1),conveying part(12.2),and gearshift lever(10.1).Most viewpoints of the cabin type Far-East combine harvester were out of the stable gaze field of the view level.Modifications of the cabin type Far-East combine harvester design will be required to enhance the visibility during harvesting operation and to improve safety and convenience of farmers.展开更多
Cabin cables,as critical components of an aircraft's electrical system,significantly impact the operational efficiency and safety of the aircraft.The existing cable segmentation methods in civil aviation cabins ar...Cabin cables,as critical components of an aircraft's electrical system,significantly impact the operational efficiency and safety of the aircraft.The existing cable segmentation methods in civil aviation cabins are limited,especially in automation,heavily dependent on large amounts of data and resources,lacking the flexibility to adapt to different scenarios.To address these challenges,this paper introduces a novel image segmentation model,CableSAM,specifically designed for automated segmentation of cabin cables.CableSAM improves segmentation efficiency and accuracy using knowledge distillation and employs a context ensemble strategy.It accurately segments cables in various scenarios with minimal input prompts.Comparative experiments on three cable datasets demonstrate that CableSAM surpasses other advanced cable segmentation methods in performance.展开更多
The design of casting gating system directly determines the solidification sequence,defect severity,and overall quality of the casting.A novel machine learning strategy was developed to design the counter pressure cas...The design of casting gating system directly determines the solidification sequence,defect severity,and overall quality of the casting.A novel machine learning strategy was developed to design the counter pressure casting gating system of a large thin-walled cabin casting.A high-quality dataset was established through orthogonal experiments combined with design criteria for the gating system.Spearman’s correlation analysis was used to select high-quality features.The gating system dimensions were predicted using a gated recurrent unit(GRU)recurrent neural network and an elastic network model.Using EasyCast and ProCAST casting software,a comparative analysis of the flow field,temperature field,and solidification field can be conducted to demonstrate the achievement of steady filling and top-down sequential solidification.Compared to the empirical formula method,this method eliminates trial-and-error iterations,reduces porosity,reduces casting defect volume from 11.23 cubic centimeters to 2.23 cubic centimeters,eliminates internal casting defects through the incorporation of an internally cooled iron,fulfilling the goal of intelligent gating system design.展开更多
Today,noise control is of critical importance.In order to provide sound insulation,parameters such as Sound Transmission Loss(STL)and sound absorption coefficient are measured in environments such as impedance tubes,A...Today,noise control is of critical importance.In order to provide sound insulation,parameters such as Sound Transmission Loss(STL)and sound absorption coefficient are measured in environments such as impedance tubes,Alpha Cabin and echo chambers.However,the low number of accredited acoustic test rooms in Turkey and the high-test costs cause these tests to be performed in limited numbers.In this direction,test box similar to the Alpha Cabin designed aims to both reduce costs and perform tests in a healthy way using natural and recyclable materials,and to prevent damage to test devices caused by hard materials.In this study,samples with STL values above 30 dB at 500–8000 Hz.were selected and tested in the designed system.As a result,it was seen that the data were close to each other.The highest value was obtained as 49.13 dB at 4000 Hz.in a 2 cm thick gypsum board,gypsum and concave walnut shell sample(moving surface L_(1)).This situation provides an important contribution in terms of sound insulation by using natural and recyclable materials and the proposed test box,meeting the experimental criteria at low cost and in the field of noise control.展开更多
This paper presents a comprehensive test and systematic evaluation analysis of cabin noise in the Robinson R44 RAVEN II helicopter.Initially,microphones were placed within the cabin to conduct systematic assessments o...This paper presents a comprehensive test and systematic evaluation analysis of cabin noise in the Robinson R44 RAVEN II helicopter.Initially,microphones were placed within the cabin to conduct systematic assessments of noise levels under various flight conditions,including takeoff,climbing,level flight,landing,hovering,etc.Subsequently,time–frequency analysis was conducted on the test data utilizing traditional A-weighted sound pressure levels,which was followed by quantitative comparisons across different flight conditions.Then,detailed evaluation and discussion were conducted,taking into account the subjective perceptions and communication challenges of cabin crew members.This assessment incorporated the use of aviation noise indicators,speech interference levels,and metrics related to sound quality.Finally,potential noise reduction measures and their effects were preliminarily discussed.The results indicate that helicopter cabin noise exhibited variations across different flight states or positions within the same state,ranging from 87.6 d B(A)to 92.6 dB(A).Discrepancies between A-weighted sound pressure level and psychoacoustic parameters were observed,particularly during hovering states,which indicate that there is a necessity for the combination of multiple evaluation indicators.Notably,damping measure can serve as a pivotal factor in mitigating cabin noise.展开更多
To investigate the explosion load characteristics and structural response law in a water mist environment in a cabin,explosion experiments are carried out.The weakening rates of the initial peak overpressure,quasistat...To investigate the explosion load characteristics and structural response law in a water mist environment in a cabin,explosion experiments are carried out.The weakening rates of the initial peak overpressure,quasistatic pressure and structural residual deflection increase with increasing working pressure of the water mist nozzle.Specifically,the weakening rate of the initial peak overpressure ranges from 7.8%to 31.0%,the quasistatic pressure weakening rate ranges from 29.2%to 41.0%,and the weakening rate of the center of the plate residual deflection ranges from 10.8%to 34.4%under the various working pressures of the nozzles.To further explore the effect of water mist explosion suppression,a method for three-dimensional numerical simulations of water mist weakening the explosion shock wave is established to explore the explosion load characteristics of the compartment and the bulkhead response law.On the basis of the dimension analysis method,empirical formulas are derived to predict the residual deflection thickness in the center of the bulkheads.These findings provide the fundamental basis for the appli-cation of water mist in anti-explosive protection.展开更多
This study examines the variations in noise levels across various subway lines in Singapore and three other cities,and provides a detailed overview of the trends and factors influencing subway noise.Most of the equiva...This study examines the variations in noise levels across various subway lines in Singapore and three other cities,and provides a detailed overview of the trends and factors influencing subway noise.Most of the equivalent sound pressure level(Leq)in typical subway cabins across the Singapore subway lines are below 85 dBA,with some notable exceptions.These variations in noise levels are influenced by several factors,including rolling stock structure,track conditions and environmental and aerodynamic factors.The spectrogram analysis indicates that the cabin noise is mostly concentrated below the frequency of 1,000 Hz.This study also analyzes cabin noise in subway systems in Suzhou,Seoul,and Tokyo to allow for broader comparisons.It studies the impact of factors such as stock materials,track conditions including the quality of the rails,the presence of curves or irregularities,and maintenance frequency on cabin noise.展开更多
Ive always been an adventure seeker,and my interest in Lake Clark National Park and Preserve was inspired when I explored Dick Proennekes story through videos and books at home.His life in that beautiful place was so ...Ive always been an adventure seeker,and my interest in Lake Clark National Park and Preserve was inspired when I explored Dick Proennekes story through videos and books at home.His life in that beautiful place was so fascinating that I knew I had to visit the lake and Proennekes cabin.Seeing the cabin in person and experiencing the place where Proenneke lived for so many years were the highlights of my trip.展开更多
The study adopted a 20-foot long container to simulate the situation inside a turbine cabin. Water mist sprays were installed internally and used to perform fire extinguishing tests. Under these different scenarios, s...The study adopted a 20-foot long container to simulate the situation inside a turbine cabin. Water mist sprays were installed internally and used to perform fire extinguishing tests. Under these different scenarios, several operating factors were adjusted with the results of each adjustment subsequently measured. The operating factors studied included： operating pressures, foam concentrations, cabin opening issues, and obstacles. Each of the factors was compared with the others so as to find out which combinations would be most suitable for a water mist spray system installed inside a wind turbine cabin. The presence of obstructions hinders the direct impact of the mist spray on the fire source and in average an additional 2 to 3 minutes is required to put out the fire. This study found that the effect of the foam-water ratio is linear. Regardless of the scenario, the optimum mixture ratio is 3%. The line graph shows that the most unsuitable aqueous film-forming mixture ratio is 6%. This experiment found that the main fire extinguishing mechanism of water mist spray is the cooling of a large area via water droplets. This system is very effective in bringing down the temperature. The addition of foam in water mist spray, however, impaired the effectiveness of the cooling effect although the fire control mechanism via emulsification markedly reduced the time required to put out the fire. The increase in foam magnification will considerably enhance the fire extinguishing efficiency.展开更多
The basic assumption of Marxist criticism is that those who control a society's economy also control or largely influence its material, cultural, and intellectual products. The Marxist criticism theory in Uncle To...The basic assumption of Marxist criticism is that those who control a society's economy also control or largely influence its material, cultural, and intellectual products. The Marxist criticism theory in Uncle Tom's Cabin is about the reality of liberation theology, and twentieth-century political resistance movement in order to expose the evilness of slavery.展开更多
The existing investigations on thermal comfort mostly focus on the thermal environment conditions,especially of the air-flow field and the temperature distributions in vehicle cabin.Less attention appears to direct to...The existing investigations on thermal comfort mostly focus on the thermal environment conditions,especially of the air-flow field and the temperature distributions in vehicle cabin.Less attention appears to direct to the thermal comfort or thermal sensation of occupants,even to the relationship between thermal conditions and thermal sensation.In this paper,a series of experiments were designed and conducted for understanding the non-uniform conditions and the occupant's thermal responses in vehicle cabin during the heating period.To accurately assess the transient temperature distribution in cabin in common daily condition,the air temperature at a number of positions is measured in a full size vehicle cabin under natural winter environment in South China by using a discrete thermocouples network.The occupant body is divided into nine segments,the skin temperature at each segment and the occupant's local thermal sensation at the head,body,upper limb and lower limb are monitored continuously.The skin temperature is observed by using a discrete thermocouples network,and the local thermal sensation is evaluated by using a seven-point thermal comfort survey questionnaire proposed by American Society of Heating,Refrigerating and Air-Conditioning Engineers,Inc(ASHRAE)Standard.The relationship between the skin temperature and the thermal sensation is discussed and regressed by statistics method.The results show that the interior air temperature is highly non-uniform over the vehicle cabin.The locations where the occupants sit have a significant effect on the occupant's thermal responses,including the skin temperature and the thermal sensation.The skin temperaWa-e and thermal sensation are quite different between body segments due to the effect of non-uniform conditions,clothing resistance,and the human thermal regulating system.A quantitative relationship between the thermal sensation and the skin temperature at each body segment of occupant in real life traffic is presented.The investigation result indicates that the skin temperature is a robust index to evaluate the thermal sensation.Applying the skin temperature to designing and controlling parameters of the heating,ventilation and air conditioning(HVAC)system may benefit the thermal comfort and reducing energy consumption.展开更多
基金supported by the Civil Aircraft Pre-research Project of China
文摘Aircraft passengers are more and demanding in terms of thermal comfort. But it is not yet easy for aircraft crew to control the environment control system （ECS） that satisfies the thermal comfort for most passengers due to a number of causes. This paper adopts a corrected predicted mean vote （PMV） model and an adaptive model to assess the thermal comfort conditions for 31 investigated flights and draws the conclusion that there does exist an uncomfortable thermal phe- nomenon in civil aircraft cabins, especially in some short-haul continental flights. It is necessary to develop an easy way to predict the thermal sensation of passengers and to direct the crew to con- trol ECS. Due to the assessment consistency of the corrected PMV model and the adaptive model, the adaptive model of thermal neutrality temperature can be used as a method to predict the cabin optimal operative temperature. Because only the mean outdoor effective temperature ET＊ of a departure city is an input variable for the adaptive model, this method can be easily understood and implemented by the crew and can satisfy 80-90% of the thermal acceptability levels of passen- gers.
文摘The emergence of the novel coronavirus has led to a global pandemic which has led to the airline industry facing severe losses. For air travel to recover, airlines need to ensure safe air travel. In this paper, the authors have modeled droplet dispersion after a single breath from an index patient. Computational Fluid Dynamics (CFD) simulations are conducted using the k-ωSST turbulence model in ANSYS Fluent. The authors have taken into consideration several parameters such as the size of the mouth opening, the velocity of the cabin air as well as the number of droplets being exhaled by the index patient to ensure a realistic simulation. Preliminary results indicate that after a duration of 20 s, droplets from the index patient disperse within a 10 m2 cabin area. About 75% of the droplets are found disperse for up to 2 m axially behind the index patient. This could possess an enhanced risk to passengers sitting behind the index patient. Ultimately, this paper provides an insight into the potential of CFD to visualise droplet dispersal and give impetus to ensure that necessary mitigating measures can be taken to reduce the risk of infection through droplet dispersal.
基金supported by the National Basic Research Program of China(973 Program)(2012CB720100)
文摘Abstract Air distribution in commercial airliner cabins is very important for the comfort and health of passengers and crew. Experimental measurements, computational fluid dynamics （CFD） simulations, and inverse modeling are state-of-the-art methods available for studying the air distri- bution. This paper gave an overview of the different experimental models, such as scale models, simplified models, full-scale mockups, and actual air cabins. Although experimental measurements were expensive and time consuming, the data were essential for validating CFD simulations. Different modeling strategies for CFD simulations were also discussed in this paper, including large eddy simulations and Reynolds averaged Navier-Stokes equation modeling. CFD simulations were main stream approaches for studying the air distribution but they could not easily lead to optimal design. Inverse modeling of air distribution has recently emerged into a very powerful and attractive tool for designing the air distribution in airliner cabins, although most of the studies were preliminary.
文摘The vibration and noise produced by the powertrain and waves inside ship cabins limit working efficiency and crew and passengers’accommodation quality.This paper simplifies ship cabins as cavities and explores active control techniques to attenuate sound transmission via multiple parallel-supported flexible subplates.The theoretical formulations of the interaction between multiple subplates and cavities were performed and the coupling relationships between them were analyzed.Based on the multiple subplates and the cavity coupling models,numerical simulations were performed using the derived optimal controller to minimize the transmission of sound into the cavities through two and nine parallel-supported subplates.The various control strategies were explored to minimize the coupling system’s acoustic potential energy,and the control performances were compared and discussed.The mechanism of reducing sound transmission through multiple supported subplates into a cavity is revealed.The simulation results showed that the vibration pattern of the controlled subplate is changed after it is regulated,which increases its radiation to subdue the other subplates’radiation,while increasing vibration of the controlled subplate.The more subplates a cavity has,the more kinetic energy the controlled subplate possess.Furthermore,the noise reduction performance of a cavity with fewer subplates is better than that with more subplates.
文摘The research of the ergonomic parameters of two tested forwarders was based on the measurement of a variability of physiological functions of the operator during one work shift. The research included a series of six measurements, each lasting l h and starting at 5：00, 12：00 and 17：00 O＇clock. The measured operator was at all times the same person. We had a hypothesis that the rate of the measured variability would have to do with the following four factors： forwarder cabin type, terrain character, fatigue during the work shift and work at daylight or in dark. Main findings are described below： during his work with a fixed type of the forwarder cab, the operator＇s brain waves at the frequency of Gamma, high Beta, Beta and Alpha reached statistically significantly higher average values than during his work with a rotating cab. With a higher degree of terrain roughness and in the forwarder with the rotating cab, the operator showed a significantly higher frequency and lower amplitude of respiration. At the beginning of the work shift, the tension of muscles in the operator＇s neck was at the significantly lowest level. In the afternoon, at the end of the work shift, the level of muscle tension was the highest. The “daylight/dark” work had a significantly highest impact on volume changes in the amplitude （strength） of blood pulse and on the skin conductance level. All research factors explained together 15%-65% of the variability of physiological functions.
文摘Seoul metropolitan subway network is known to be the one of the most heavily used transportation means in the world. The subway cabins are naturally ventilated when the cabin doors are opened and through the gaps caused by the incomplete air-tightening of cabin bodies. Although, subway trains are equipped with a mechanical exhaust fan, the apparatus is rarely operated due to the problem of heating/cooling efficiency especially in the summer and winter seasons. In this study, we analyzed the transient CO2 （carbon dioxide） concentration level during the journey of a subway cabin when a heavy load of passengers of up to 200% of designed capacity using a CFD （computational fluid dynamics） analysis. With an increased journey time, the CO2 concentration increased by up to 5,000 ppm depending on passenger load. Through the operation of a mechanical exhaust fan, the high concentration of CO2 decreased down to 1,500 ppm. The effect of the exhaust fan operating on the dilution of indoor air was estimated by comparison with a closed cabin. In addition, the energy consumption for cooling in summer time was assessed for exhaust fan operations.
文摘Air pollution induces significant health risks to individuals exposed to high levels of pollutants concentration. For ground vehicles, pollutants infiltrate the car cabin through the ventilation system, leading to potential health issues. To address this problem, a project was undertaken to develop a protocol for characterizing in-cabin air quality. The study involved a closed chamber (the bubble) where its internal multiphase flow has been optimized to create controlled polluted atmospheres. Experiments were conducted to optimize the positioning of the stirring fan and particle generation source, ensuring a homogeneous distribution of fine and ultrafine particles. This study demonstrated the feasibility of implementing a platform dedicated to characterizing the vehicles’ in-cabin air quality under controlled conditions. It allows a better understanding of the dynamics of particle infiltration and the establishment of an optimized protocol for simultaneous measurements of indoor and outdoor concentrations.
文摘With projections indicating an increase in mobility over the next few decades andannual flight departures expected to rise to over 16 billion by 2050,there is a demand for theaviation industry and associated stakeholders to consider new forms of aircraft and technology.Customer requirements are recognized as a key driver in business.The airline is the principalcustomer for the aircraft manufacture.The passenger is,in turn,the airline's principal customerbut they are just one of several stakeholders that include aviation authorities,airport operators,air-traffic control and security agencies.The passenger experience is a key differentiator usedby airlines to attract and retain custom and the fuselage that defines the cabin envelope for thein-flight passenger experience and cabin design therefore receives significant attention for newaircraft,service updates and refurbishments.Decision making in design is crucial to arrivingat viable and worthwhile cabin formats.Too litle innovation will result in an aircraftmanufacturer and airlines using its products falling behind its competitors.Too much mayresult in an over-extension with,for example,use of immature technologies that do not havethe necessary reliability for a safety critical industry or sufficient value to justify the develop-ment effort.The multiple requirements associated with cabin design,can be viewed as an area for optimisation,accepting trade-offs between the various parameters.Good design,however,is often defined as developing a concept that resolves the contradictions and takes the solutiontowards a win-win scenario.Indeed our understanding and practice of design allows forbehaviors that enhance design thinking through divergence and convergence,the use ofabductive reasoning,experimentation and systems thinking.This paper explores and definesthe challenges of designing the aireraft cabin of the future that will deliver on the multiplerequirements using experiences from the A350 XWB and future cabin design concepts.Inparticular the paper explores the value of implementing design thinking insights in engineeringpractice and discusses the relative merits of decisions based on optimisation versus win-winscenarios for aircraft cabin design and wider applications in aerospace environments.Theincreasing densification of technological opportunities and shifting consumer demand coupledwith highly complex systems may ultimately challenge our ability to make decisions based onoptimisation balances.From an engineering design perspective optimisation tends to precludecertain strategies that deliver high quality results in consumer scenarios whereas win-winsolutions may face challenges in complex technical environments.
文摘The purpose of this study was to develop and evaluate a visibility evaluation system for the cabin type Far-East combine harvester.The human field of view has been classified into five levels(perceptive,effective,stable gaze,induced,and auxiliary)depending on the rotation of the human head and eye.The divider,reaper lever,gearshift,dashboard,and conveying component were considered as major viewpoints of the cabin type Far-East combine harvester.The visibility of the cabin type Far-East combine harvester was evaluated quantitatively using viewpoints and human field of view levels.The visibility evaluation system for the cabin type Far-East combine harvester consisted of a laser pointer,stepping motors to control the directions of the view,gyro sensors to measure horizontal and vertical angles,and I/O interface to acquire the signals.The visibility evaluation tests were conducted at different postures(‘sitting straight’,‘sitting with a 15°tilt’,‘standing straight’,and‘standing with a 15°tilt’)for three cabin type Far-East combine harvesters.The LSD(least significant difference)multiple comparison tests showed that the visibilities of viewpoints differed significantly as the operator's posture changed.The results showed that the posture while standing with a 15°tilt provided the best visibility.The average visibility scores at sitting postures were 22.3(straight)and 24.4(15°tilt),and the scores at standing postures were 18.7(straight)and 29.5(15°tilt).Also,the average visibility scores were observed in order from highest to lowest as reaper lever(44.6),divider(28.7),dashboard(23.1),conveying part(12.2),and gearshift lever(10.1).Most viewpoints of the cabin type Far-East combine harvester were out of the stable gaze field of the view level.Modifications of the cabin type Far-East combine harvester design will be required to enhance the visibility during harvesting operation and to improve safety and convenience of farmers.
基金supported by the Innovation Foundation of National Commercial Aircraft Manufacturing Engineering Technology Research Center(No.COMAC-SFGS-2022-1877)in part by the National Natural Science Foundation of China(No.92048301)。
文摘Cabin cables,as critical components of an aircraft's electrical system,significantly impact the operational efficiency and safety of the aircraft.The existing cable segmentation methods in civil aviation cabins are limited,especially in automation,heavily dependent on large amounts of data and resources,lacking the flexibility to adapt to different scenarios.To address these challenges,this paper introduces a novel image segmentation model,CableSAM,specifically designed for automated segmentation of cabin cables.CableSAM improves segmentation efficiency and accuracy using knowledge distillation and employs a context ensemble strategy.It accurately segments cables in various scenarios with minimal input prompts.Comparative experiments on three cable datasets demonstrate that CableSAM surpasses other advanced cable segmentation methods in performance.
基金supported by the National Natural Science Foundation of China(Nos.52074246,52275390,52375394)the National Defense Basic Scientific Research Program of China(No.JCKY2020408B002)the Key R&D Program of Shanxi Province(No.202102050201011).
文摘The design of casting gating system directly determines the solidification sequence,defect severity,and overall quality of the casting.A novel machine learning strategy was developed to design the counter pressure casting gating system of a large thin-walled cabin casting.A high-quality dataset was established through orthogonal experiments combined with design criteria for the gating system.Spearman’s correlation analysis was used to select high-quality features.The gating system dimensions were predicted using a gated recurrent unit(GRU)recurrent neural network and an elastic network model.Using EasyCast and ProCAST casting software,a comparative analysis of the flow field,temperature field,and solidification field can be conducted to demonstrate the achievement of steady filling and top-down sequential solidification.Compared to the empirical formula method,this method eliminates trial-and-error iterations,reduces porosity,reduces casting defect volume from 11.23 cubic centimeters to 2.23 cubic centimeters,eliminates internal casting defects through the incorporation of an internally cooled iron,fulfilling the goal of intelligent gating system design.
文摘Today,noise control is of critical importance.In order to provide sound insulation,parameters such as Sound Transmission Loss(STL)and sound absorption coefficient are measured in environments such as impedance tubes,Alpha Cabin and echo chambers.However,the low number of accredited acoustic test rooms in Turkey and the high-test costs cause these tests to be performed in limited numbers.In this direction,test box similar to the Alpha Cabin designed aims to both reduce costs and perform tests in a healthy way using natural and recyclable materials,and to prevent damage to test devices caused by hard materials.In this study,samples with STL values above 30 dB at 500–8000 Hz.were selected and tested in the designed system.As a result,it was seen that the data were close to each other.The highest value was obtained as 49.13 dB at 4000 Hz.in a 2 cm thick gypsum board,gypsum and concave walnut shell sample(moving surface L_(1)).This situation provides an important contribution in terms of sound insulation by using natural and recyclable materials and the proposed test box,meeting the experimental criteria at low cost and in the field of noise control.
基金the Natural Science Foundation of Sichuan Province,China(Nos.2023NSFSC0902,2024ZYD0083)the Open Project of Key Laboratory of Aerodynamic Noise Control of China Aerodynamics Research and Development Center(No.ANCL20220202)+1 种基金the Open Project of Key Laboratory of Flight Techniques and Flight Safety,CAAC,China(No.FZ2022KF01)the Fundamental Research Funds for the Central Universities,China(No.24CAFUC01007)。
文摘This paper presents a comprehensive test and systematic evaluation analysis of cabin noise in the Robinson R44 RAVEN II helicopter.Initially,microphones were placed within the cabin to conduct systematic assessments of noise levels under various flight conditions,including takeoff,climbing,level flight,landing,hovering,etc.Subsequently,time–frequency analysis was conducted on the test data utilizing traditional A-weighted sound pressure levels,which was followed by quantitative comparisons across different flight conditions.Then,detailed evaluation and discussion were conducted,taking into account the subjective perceptions and communication challenges of cabin crew members.This assessment incorporated the use of aviation noise indicators,speech interference levels,and metrics related to sound quality.Finally,potential noise reduction measures and their effects were preliminarily discussed.The results indicate that helicopter cabin noise exhibited variations across different flight states or positions within the same state,ranging from 87.6 d B(A)to 92.6 dB(A).Discrepancies between A-weighted sound pressure level and psychoacoustic parameters were observed,particularly during hovering states,which indicate that there is a necessity for the combination of multiple evaluation indicators.Notably,damping measure can serve as a pivotal factor in mitigating cabin noise.
基金supported by the National Natural Science Foundation of China(grant numbers:52201334)sup-ported by National Key Laboratory of Ship Structural Safety(grant numbers:Naklas2024-KF015-s).
文摘To investigate the explosion load characteristics and structural response law in a water mist environment in a cabin,explosion experiments are carried out.The weakening rates of the initial peak overpressure,quasistatic pressure and structural residual deflection increase with increasing working pressure of the water mist nozzle.Specifically,the weakening rate of the initial peak overpressure ranges from 7.8%to 31.0%,the quasistatic pressure weakening rate ranges from 29.2%to 41.0%,and the weakening rate of the center of the plate residual deflection ranges from 10.8%to 34.4%under the various working pressures of the nozzles.To further explore the effect of water mist explosion suppression,a method for three-dimensional numerical simulations of water mist weakening the explosion shock wave is established to explore the explosion load characteristics of the compartment and the bulkhead response law.On the basis of the dimension analysis method,empirical formulas are derived to predict the residual deflection thickness in the center of the bulkheads.These findings provide the fundamental basis for the appli-cation of water mist in anti-explosive protection.
文摘This study examines the variations in noise levels across various subway lines in Singapore and three other cities,and provides a detailed overview of the trends and factors influencing subway noise.Most of the equivalent sound pressure level(Leq)in typical subway cabins across the Singapore subway lines are below 85 dBA,with some notable exceptions.These variations in noise levels are influenced by several factors,including rolling stock structure,track conditions and environmental and aerodynamic factors.The spectrogram analysis indicates that the cabin noise is mostly concentrated below the frequency of 1,000 Hz.This study also analyzes cabin noise in subway systems in Suzhou,Seoul,and Tokyo to allow for broader comparisons.It studies the impact of factors such as stock materials,track conditions including the quality of the rails,the presence of curves or irregularities,and maintenance frequency on cabin noise.
文摘Ive always been an adventure seeker,and my interest in Lake Clark National Park and Preserve was inspired when I explored Dick Proennekes story through videos and books at home.His life in that beautiful place was so fascinating that I knew I had to visit the lake and Proennekes cabin.Seeing the cabin in person and experiencing the place where Proenneke lived for so many years were the highlights of my trip.
文摘The study adopted a 20-foot long container to simulate the situation inside a turbine cabin. Water mist sprays were installed internally and used to perform fire extinguishing tests. Under these different scenarios, several operating factors were adjusted with the results of each adjustment subsequently measured. The operating factors studied included： operating pressures, foam concentrations, cabin opening issues, and obstacles. Each of the factors was compared with the others so as to find out which combinations would be most suitable for a water mist spray system installed inside a wind turbine cabin. The presence of obstructions hinders the direct impact of the mist spray on the fire source and in average an additional 2 to 3 minutes is required to put out the fire. This study found that the effect of the foam-water ratio is linear. Regardless of the scenario, the optimum mixture ratio is 3%. The line graph shows that the most unsuitable aqueous film-forming mixture ratio is 6%. This experiment found that the main fire extinguishing mechanism of water mist spray is the cooling of a large area via water droplets. This system is very effective in bringing down the temperature. The addition of foam in water mist spray, however, impaired the effectiveness of the cooling effect although the fire control mechanism via emulsification markedly reduced the time required to put out the fire. The increase in foam magnification will considerably enhance the fire extinguishing efficiency.
文摘The basic assumption of Marxist criticism is that those who control a society's economy also control or largely influence its material, cultural, and intellectual products. The Marxist criticism theory in Uncle Tom's Cabin is about the reality of liberation theology, and twentieth-century political resistance movement in order to expose the evilness of slavery.
基金supported by National Natural Science Foundation of China(Grant No.51375170)Open Fund of State Key Lab of Environmental Adaptability for Industrial Products of China
文摘The existing investigations on thermal comfort mostly focus on the thermal environment conditions,especially of the air-flow field and the temperature distributions in vehicle cabin.Less attention appears to direct to the thermal comfort or thermal sensation of occupants,even to the relationship between thermal conditions and thermal sensation.In this paper,a series of experiments were designed and conducted for understanding the non-uniform conditions and the occupant's thermal responses in vehicle cabin during the heating period.To accurately assess the transient temperature distribution in cabin in common daily condition,the air temperature at a number of positions is measured in a full size vehicle cabin under natural winter environment in South China by using a discrete thermocouples network.The occupant body is divided into nine segments,the skin temperature at each segment and the occupant's local thermal sensation at the head,body,upper limb and lower limb are monitored continuously.The skin temperature is observed by using a discrete thermocouples network,and the local thermal sensation is evaluated by using a seven-point thermal comfort survey questionnaire proposed by American Society of Heating,Refrigerating and Air-Conditioning Engineers,Inc(ASHRAE)Standard.The relationship between the skin temperature and the thermal sensation is discussed and regressed by statistics method.The results show that the interior air temperature is highly non-uniform over the vehicle cabin.The locations where the occupants sit have a significant effect on the occupant's thermal responses,including the skin temperature and the thermal sensation.The skin temperaWa-e and thermal sensation are quite different between body segments due to the effect of non-uniform conditions,clothing resistance,and the human thermal regulating system.A quantitative relationship between the thermal sensation and the skin temperature at each body segment of occupant in real life traffic is presented.The investigation result indicates that the skin temperature is a robust index to evaluate the thermal sensation.Applying the skin temperature to designing and controlling parameters of the heating,ventilation and air conditioning(HVAC)system may benefit the thermal comfort and reducing energy consumption.
