Cabin Interior Research Articles

Psychoacoustic Bias in Vehicle Interior Noise – Preliminary Study

This paper presents a preliminary study of psychoacoustic response bias in vehicle interior noise. The subjective response in psychoacoustics require human subject with relevant background and tendency for the best data analysis. In the vehicle interior sound quality subjective investigation, different vehicle owner have different expectation in vehicle comfort based on their preference. The perception and hearing sensitivity will be based on their day-to-day exposure. The objective of this paper is to study the bias response in vehicle sound quality judgement for different categories of car user (such as compact, sedan and luxury car). In this study, a survey has been conducted in an automotive service workshop. The questionnaire was designed to obtain the perception towards overall vehicle interior noise. The questionnaire are divided into three section; Part I: demographic information, Part II: Customer comfort level on level in vehicle cabin, Part III: Customer comfort level of sound loudness. The part III questions is created based on Loudness Fastl's Thermometer. The respondents were given brief demonstration of loudness and sharpness. Two examples of each type were given to assist respondent in grasping the concept and come out with their judgement toward the related sound mentioned in the survey. In this study, 30 male and 12 female respondents participated in the survey. The results showed80% of the respondents feel comfort with their respective vehicle regardless of what type of car there are driving. This indicates clear bias response based on the user's experience in driving different type of car. In a nutshell, different car owner define comfort level differently. Even if the sound level is different in comfort, sedan and luxury car, the driver still feel comfort which lead to different perception in defining vehicle cabin interior noise comfort.

D7-3 From the Point of a Tower Crane Operator's View: Use of an Eye-Tracker in Construction Sites

The need for high-rise building constructions, large-scale apartment blocks, or construction in urban areas raised the number of tower crane use. For safe and efficient activities in construction sites; tower crane type selection, decision of tower crane location, decision of load type, load location, specified area, and their supply, securing equipment, also the work schedules and maintenance should carefully be planned. This study proposes a methodology to support accident management in construction sites where a single tower crane is used. Aim is to identify the risks during operations and rank the severity levels of the activities to avoid property damage and bodily injuries. Up to best knowledge, a mobile type eye-tracker is used for the first time to record the view of tower crane operator during operations. In the first step, operator is asked to wear the eye-tracker as a regular glasses and climb the operating cabin that is attached to the structure of the tower crane. Based on the video records, it is possible assess not only the guiderails, handholds, steps, and trap door but also the operating cabin interior design in terms of control unit locations, window panels. In the second step, the data collected during material handling operations is used to assess the location of loads, potential risks for the slinger who is responsible for attaching and detaching the load to and from the crane and the signaler who is responsible for relaying the signal from the slinger to the crane operator and directing the safe movement of the crane. The visual attention of the tower crane operator and working postures are evaluated. In the third step, the records when tower crane operator is descending the ladder of the tower are considered. Obtained data is interpreted as indicators of fatigue such as duration of fixation, number of fixation, and pupil size change. Data obtained from two construction sites (one constructed near the single building construction site and other between two buildings construction site) where one tower crane is used to test the hypothesis. Results illustrate that the location of tower crane have a significant effect on safe operations for the crane operator. Further comments are made based on the possible impacts of communication system, high visibility clothing, and weather conditions for an efficient accident management.

Recent Advances in Active Noise Control Inside Automobile Cabins: Toward quieter cars

Minimization of interior cabin noise has been a key topic of research in the automobile industry for the last two decades. This problem was initially approached via passive noise cancelation methods, where physical treatments such as structural damping and acoustic absorption were used. However, with vehicle manufacturers striving for more economical and lightweight designs, the resulting car interiors invariably became noisier due to the increased structural vibrations. These noise fields are generally dominanted by low frequencies (i.e., 0-500 Hz) [1], [2], hence, the conventional passive noise cancelation approaches are less effective. In an attempt to resolve the aforementioned problem, active noise control (ANC) methods were developed where secondary sources were proposed to attenuate the noise inside the cabin. With modern in-car entertainment systems providing four to six built-in loudspeakers, the addition of an ANC system comes at a relatively low additional cost.

Workspace design for crane cabins applying a combined traditional approach and the Taguchi method for design of experiments

Procedures in the development process of crane cabins are arbitrary and subjective. Since approximately 42% of incidents in the construction industry are linked to them, there is a need to collect fresh anthropometric data and provide additional recommendations for design. In this paper, dimensioning of the crane cabin interior space was carried out using a sample of 64 crane operators’ anthropometric measurements, in the Republic of Serbia, by measuring workspace with 10 parameters using nine measured anthropometric data from each crane operator. This paper applies experiments run via full factorial designs using a combined traditional and Taguchi approach. The experiments indicated which design parameters are influenced by which anthropometric measurements and to what degree. The results are expected to be of use for crane cabin designers and should assist them to design a cabin that may lead to less strenuous sitting postures and fatigue for operators, thus improving safety and accident prevention.

Conforto e desconforto em cabines de aeronaves: um método baseado na análise da atividade

Resumo A literatura mostra que as poltronas aeronáuticas usualmente são avaliadas por métodos objetivos em experimentos estáticos e realizados fora do seu contexto de uso. O objetivo deste artigo é apresentar um método que utiliza medição contínua de pressão de interface ocupante-poltrona em conjunto com outras técnicas, como observação, relato pós-experimento e filmagem para avaliar o conforto e o desconforto de poltronas e cabines de aeronaves em suas fases de concepção e desenvolvimento. Na primeira etapa do método, os participantes avaliaram as condições para realizar as atividades de ler e repousar em ensaios de 40 minutos, realizados em um simulador de interior de cabine de aeronave. Na segunda etapa, foi realizada uma sessão de brainstorming para gerar ideias e captar oportunidades de melhoria para a poltrona e a cabine da aeronave avaliada. Na última etapa, uma solução sugerida no brainstorming foi prototipada e avaliada em condição de uso.

Finite Element Approach to Identify the Potential of Improved Heavy-Truck Crashworthiness and Occupant Protection in Frontal Impacts

Interior crash protection has not yet received adequate attention for heavy trucks, as such protection did for automobiles. The goal of this pilot project was to determine the nature of truck crashes that would remain after full deployment of advanced collision avoidance technologies and to assess the crashes with respect to truck driver injury and prevention. Heavy-truck occupant safety was analyzed according to injury pattern and severity to help identify and characterize heavy-truck crashes to define opportunities for improved truck crashworthiness and reduce truck driver fatalities and injuries. A finite element (FE) model combining heavy-truck cabin structure, interior components, dummy, and passive restraint systems was developed to simulate a head-on crash into a rigid barrier at 35 mph, the impact conditions used with the NHTSA new car assessment program test. This crash also represented an impact condition that was overrepresented in real-world crash data and for which there was room for improvement in occupant safety. A full FE tractor semitrailer model was employed to collect the crash pulse resulting on the truck cab as outcome of the computer simulation, which was then applied to defined locations of the FE cab model. Acceleration data were collected from impact of different parts of the dummy with interior components of the occupant compartment to assist in the calculation of body injury levels. The researchers developed a comparative risk study to evaluate the effectiveness of passive safety restraints, which would lead to preliminary guidance on the effectiveness of the use of such occupant injury mitigation systems.

Active and passive techniques for a cost-effective noise reduction in the interior of aircraft cabins

Different noise reduction techniques that can be applied to the interior of aircraft cabin are investigated, to determine the most cost-effective means, without any aircraft external modifications, such as jet engine design change, or fuselage modifications, with no significant added weight. The goal of this research is to arrive at a cabin interior design that can be retrofitted to the existing aircraft interior to reduce overall cabin noise. Relaxation oscillations of the aircraft cabin model, considered as a system in forced vibrations with non-linear damping, and sub-harmonic resonances are considered. Negative and positive damping coefficients, and some techniques for noise cancelation by active means are discussed. From noise power-spectrum results for a typical aircraft cabin, amplitude versus audible frequency, one can determine the most energetic cabin vibration modes. Those modes require the highest damping. The proposed technique will utilize a regular matrix of the multiple sets of open Helmholtz resonators, with sound absorbing surfaces, that are imbedded in the cabin interior walls, just below the surface, and tuned to the highest noise level frequencies inside the cabin. The resonators dissipate the noise energy inside the aircraft at the most dominant frequencies, and hence reduce the overall cabin noise level.

Fast Active Sound Tuning System for Vehicle Powertrain Response

ABSTRACT This paper describes an active sound tuning (AST) system for vehicle powertrain response. Instead of simply aiming to attenuate cabin interior noise, AST system is capable of reshaping the powertrain response based on predetermined vehicle sound quality criteria. However, conventional AST systems cannot yield a balanced result over the broad frequency range when applied to powertrain noise. It is due to the fact that existing systems are typically configured with the filtered-x least mean square (FXLMS) algorithm or its modified versions, which has inherent frequency dependent convergence behavior due to large dynamic range of secondary path (the electro-acoustic path from the control speaker to the error microphone). Therefore, fast convergence can only be reached at the resonant frequencies. To overcome this inherent limitation, an enhanced adaptive notch filter with inverse model least mean square (ANF-IMLMS) algorithm is proposed as a basis of the AST system for vehicle powertrain response. Compared with the traditional FXLMS algorithm, the proposed algorithm not only increases the convergence speed, but also reduces the computational complexity. Thus, the overall performance of the AST system is improved. Numerical simulation applying measured powertrain data is conducted to validate the performance of the proposed system. Results demonstrate that the proposed system has improved spectral shaping capability with fast convergence.

Net in-cabin emission rates of VOCs and contributions from outside and inside the aircraft cabin

Volatile organic compounds (VOCs) are one of the most important types of air pollutants in aircraft cabin. Balancing source intensity of VOCs and ventilation strategies is an essential conducive way to obtain acceptable aircraft cabin environment. This paper intends to develop a simplified model by a case study to estimate the net VOC emission rates of cabin interior, and contributions from outside and inside the aircraft cabin. In-flight continuous measurements of total VOCs (TVOC) in cabin air were made in six domestic flights in March 2013. The results indicate that the concentrations of TVOC mostly ranged from 0.20 mg m−3 to 0.40 mg m−3 in cabin air, which first increased at ascent, and then kept elevated during cruise, and decreased at descent in general. For further ventilation information, carbon dioxide (CO2) in supply air and re-circulated air was simultaneously observed as a ventilation tracer to calculate the bleed air ratios, outside airflow rates and total airflow rates in these flights. And thus, the emission rates derived from cabin interior and contributions of TVOC from bleed air and cabin interior were estimated for the whole flight accordingly. Results indicate that during the cruise phase, TVOC in cabin air mainly came from cabin interiors. However, contributions from outside air also became significant during taxiing on the ground, ascent and descent phases. The simplified model would be useful for developing better control strategies of aircraft cabin air quality.

Ergonomic design of crane cabin interior: The path to improved safety

Many procedures in the development process of crane cabins today are still based on the specific experience of manufacturers and historical guidelines. It is not surprising that they fail to meet the needs of a large proportion of operators. Accordingly, the need for more objective, theoretically justified and consistent models, that will minimize crane operators’ biomechanical and visual problems through anthropometric characteristic analysis to improve safety and prevent crane related fatalities and injuries, arises. In that aim we firstly identified the critical characteristics of existing crane cabins linked to visibility and posture (seat and armrest problems) using users’ opinions and Pareto analysis. We then collected rarely available data on crane operators in Serbian companies (64 in the first and 10 operators in the control sample) and proposed methodology for the ergonomic assessment of crane cabins based on drawing-board mannequins and kinematic modeling. The implemented methodology interval estimate obtains an interior space of 1095×1150×1865mm in which is possible to eliminate the critical characteristics of existing crane cabins. The research results fulfill user needs not satisfied in existing crane cabins and suggest certain changes to existing standards on the path to improved safety.

Corrected Statistical Energy Analysis Model for Car Interior Noise

Statistical energy analysis (SEA) is a well-known method to analyze the flow of acoustic and vibration energy in a complex structure. For an acoustic space where significant absorptive materials are present, direct field component from the sound source dominates the total sound field rather than a reverberant field, where the latter becomes the basis in constructing the conventional SEA model. Such environment can be found in a car interior and thus a corrected SEA model is proposed here to counter this situation. The model is developed by eliminating the direct field component from the total sound field and only the power after the first reflection is considered. A test car cabin was divided into two subsystems and by using a loudspeaker as a sound source, the power injection method in SEA was employed to obtain the corrected coupling loss factor and the damping loss factor from the corrected SEA model. These parameters were then used to predict the sound pressure level in the interior cabin using the injected input power from the engine. The results show satisfactory agreement with the directly measured SPL.

Computational modeling of passenger amphibian aircraft Be-200 cabin interior

This paper examines issues regarding computational modeling of multipurpose passenger amphibian aircraft Be-200 cabin interior. Here different concepts of cabin layout are introduced: economy variant; comfortable layout; with coupe-type seating; corporate variant with berths. Objects interior is designed on the basis of ergonomic principles. For cabin computational modeling the 3ds Max graphic system is used. Objects modeling is carried out by means of Spline Extrude, Polygon Extrude methods. In course of scenes shading, the materials assignment is performed at the level of subobjects. Scenes of realistic rendering of various aircraft cabin layouts are introduced.

Time-Frequency Analysis of Cabin Noise Using EEMD-ICA Approaches

The interior noise of construction machinery is complex non-stationary signal caused by a variety of excitation source; the noise source must be determined to minimize its radiation. There are, however, considerably fewer techniques available if only a single-channel measurement is available and yet single-channel measurements are important where minimal instrumentation complexity is required. The combined techniques of empirical mode decomposition (EEMD) and the improvement of independent component analysis (ICA) were applied to analysis the parotic noise signals of bulldozer cabin in our study. According to the correlated measurement standard, the combining method of experiment and analysis for the cabin interior and outside noise and vibration signals was applied to research the noise source effectively. With the experiment and coherence analysis for the cabin interior and outside noise and vibration signals, the techniques of EEMD-ICA were valid on the noise source separation and identification. Taking into account the machine running characteristics and the layout of machine structures, and based on the frequency characteristics of the noise and vibration signals, we concluded that the main sources of indoor noise was combustion noise of diesel engine and mechanical radiation noise of cabin parts caused by the diesel engine vibration transmission. Generation of noise sources, transmission paths of air-borne or structure-borne noises were well researched in order to control the interior noise. Finally, some modifications were taken for different noise sources and the noise level was reduced to a satisfied level.

The thematic structure of passenger comfort experience and its relationship to the context features in the aircraft cabin

This paper describes passenger comfort as an experience generated by the cabin interior features. The findings of previous studies are affirmed regarding a set of 22 context features. Passengers experience a certain level of comfort when these features impact their body and elicit subjective perceptions. New findings characterise these perceptions in the form of eight themes and outline their particular eliciting features. Comfort is depicted as a complex construct derived by passengers' perceptions beyond the psychological (i.e. peace of mind) and physical (i.e. physical well-being) aspects, and includes perceptual (e.g. proxemics) and semantic (e.g. association) aspects. The seat was shown to have a focal role in eliciting seven of those themes and impacting comfort through its diverse characteristics. In a subsequent study, a group of aircraft cabin interior designers highlighted the possibility of employing the eight themes and their eliciting features as a framework for design and evaluation of new aircraft interiors.

Tiltrotor cabin noise control through smart actuators

This paper deals with the abatement of the tonal noise inside the fuselage of a mid-range tiltrotor aircraft, as generated by the propulsive system. The problem is basically multidisciplinary, involving interactions among the exterior noise field, elastic fuselage dynamics, interior acoustics and control system. A stiffened fuselage, with piezoelectric patches embedded into the structure, is supposed to be impinged on by the aeroacoustic field generated by propellers and excited by the wing/pylon/proprotor vibratory loads at the wing–fuselage attachment. An optimal linear quadratic regulator cyclic control formulation, coupled with a genetic optimization algorithm, is applied to synthesize the control law driving the smart actuators so as to alleviate cabin noise. The aeroacoustoelastic model considered in the control problem is obtained by combining cabin interior acoustics, fuselage smart shell dynamics and wing/pylon/proprotor aeroelasticity described through modal approaches with the exterior pressure field provided by boundary element method solvers. Numerical results examine the effectiveness and robustness of the proposed active control strategy.

Source apportionment of airborne particles in commercial aircraft cabin environment: Contributions from outside and inside of cabin

Airborne particles are an important type of air pollutants in aircraft cabin. Finding sources of particles is conducive to taking appropriate measures to remove them. In this study, measurements of concentration and size distribution of particles larger than 0.3 μm (PM>0.3) were made on nine short haul flights from September 2012 to March 2013. Particle counts in supply air and breathing zone air were both obtained. Results indicate that the number concentrations of particles ranged from 3.6 × 102 counts L−1 to 1.2 × 105 counts L−1 in supply air and breathing zone air, and they first decreased and then increased in general during the flight duration. Peaks of particle concentration were found at climbing, descending, and cruising phases in several flights. Percentages of particle concentration in breathing zone contributed by the bleed air (originated from outside) and cabin interior sources were calculated. The bleed air ratios, outside airflow rates and total airflow rates were calculated by using carbon dioxide as a ventilation tracer in five of the nine flights. The calculated results indicate that PM>0.3 in breathing zone mainly came from unfiltered bleed air, especially for particle sizes from 0.3 to 2.0 μm. And for particles larger than 2.0 μm, contributions from the bleed air and cabin interior were both important. The results would be useful for developing better cabin air quality control strategies.

AN EXPERIMENTAL EVALUATION OF FIBER REINFORCED POLYPROPYLENE THERMOPLASTICS FOR AEROSPACE APPLICATIONS

Fiber reinforced thermosetting composites have wide scope in the field of Aerospace and MilitaryApplications. These materials exhibit high strength and high stiffness, besides these composites have long fatiguelife, corrosion resistance, environmental stability, thermal insulation and conductivity. Researchers areexploring possibilities to use natural fiber reinforced polymer composites (NFRPCs) in response to the increasingdemand for environmentally friendly materials and also to develop reusable fiber reinforced thermoplastics withthe desire to reduce the cost and to promote the replacement of thermosetting composites.In this work efforts are put to fabricate fiber thermoplastics made of jute, glass and carbon with (PP)polypropylene as the matrix. The mechanical strength of these fiber reinforced thermoplastics was evaluated andcompared with that of fiber reinforced thermosetting polymers made of same fibers along with epoxy matrix. Thetests clearly indicate that the laminates made of fiber reinforced polypropylene have 7 to 8 times less strengthcompared to thermosetting polymers made of fiber epoxy and it is found that for achieving better strength of thematerial, the polypropylene layers should be more than that of the epoxy matrix or to use alternative thermoplasticmaterials like polyphenylene sulfide (PPS), polyetherimide (PEI) and polyetheretherketone (PEEK). Hence thesematerials are feasible for fabricating low load bearing aircraft interior cabin parts and automobile interiorswhich can be reused or reshaped making them easy to re-work and repair.DOI: http://dx.doi.org/10.3329/jme.v43i2.17832

Improvement of noise reduction performance for a high-speed elevator using modified active noise control

A high rise building demands a high-speed elevator. Since a high-speed elevator has various transfer paths of noise transmitted from motor and rope to cabin interior, it is very difficult to solve the noise problem. Most research for noise reduction has been performed regarding passive noise control by using mainly absorption material and insulation material. In this study, while it is modeling as multiple-input and single-output with respect to transfer paths of high-speed elevator on conditions of stationary and driving states, the characterized frequency in the cabin is discovered through a contribution technique. It is able to replace by 1-dimensional model to control noise at a major contributed frequency. Also, a new active noise control technique has been proposed to control the cabin noise effectively at unpleasant area that is required to make quite zone for passenger. The Correlation Filtered X-LMS (Co-FXLMS) algorithm has been applied to control the dominant frequency noise that it has a high contribution. Simultaneously, this study has a proposed Moving Band Pass Filter (MBPF) to improve the performance of active noise control in the cabin which is able to apply a dynamic system with time variant states. Finally, we obtained the 8dB noise reduction in the cabin at ear level and it has been proved that the modified active noise control using Co-FXLMS algorithm and MBPF is available to improve the performance of noise reduction.

A computational-efficient active sound tuning system for steady-state and transient vehicle powertrain response

Conventional vehicle active noise control (ANC) methods aimed mainly at attenuating the cabin interior noise usually do not account for sound quality effects. In this paper, an active sound tuning (AST) system is proposed to reshape the vehicle powertrain response based on the predetermined vehicle interior sound quality criteria. Since it is important to develop a computational-efficient algorithm in real-world application, the time-frequency domain filtered-x least mean square (TF-FXLMS) algorithm is utilised in the AST system. The proposed TF-FXLMS algorithm significantly reduces the computational complexity compared to the conventional time-domain FXLMS algorithm by calculating the gradient estimate in frequency domain. The proposed AST system applied to powertrain response is validated by tuning individual engine order response, which is targeted for either enhancement or attenuation, under both steady-state and transient operating conditions.

High-Frequency Time Domain Source Path Contribution: From Engine Test Bench Data to Cabin Interior Sounds

High-Frequency Time Domain Source Path Contribution: From Engine Test Bench Data to Cabin Interior Sounds