1,720,983 research outputs found
Non-linear dynamic response of the seated person to whole-body vibration
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Difference thresholds for automobile seat vibration
No full textReductions in vehicle vibration that may contribute to improvements in overall vehicle ride could individually be too small to be detected by drivers or passengers. This study investigated the ‘difference threshold’ (the difference in magnitude between two stimuli which is just sufficient for their difference to be detected) required for a change in vehicle ride to be perceived and whether this was consistent with Weber's Law. Ten male and 10 female subjects sat in a car seat and were exposed to four different reproductions of the vertical vibration recorded on the seat of a car. Three of the stimuli had the same waveform recorded while the car traversed a tarmac surface. This waveform was reproduced using three different magnitudes of vibration at the seat: 0.2, 0.4 and 0.8 m s-2 r.m.s. (Wb weighted). The other stimulus was recorded with the car traversing a 'pavé' surface that gave a different waveform that was reproduced at a magnitude of 0.4 m s-2 r.m.s. (Wb weighted). There were significant differences in the absolute difference thresholds measured using the same waveform at the three different magnitudes. When the difference thresholds were expressed in relative terms (the proportion by which two stimuli must differ in magnitude to be discriminated), the relative difference thresholds were approximately 13%, and independent of both the vibration magnitude and the vibration waveform. The results are therefore consistent with Weber's Law. No consistent differences were observed between the responses of male and female subjects
Objective comparison of two cushions: pressure distribution and postural perceived discomfort
No full textDesigning seats is crucial not only for health issues but also for the (dis)comfort perception. The seat pan design could be mainly influenced by two factors: pressure distribution and seat contour. For seat pan discomfort, the lower average pressure is accompanied by less discomfort. Moreover, a seat contour with a large contact area is correlated with more comfort. So, a shaped seat pan was accurately realized following the buttock-thigh shape of an international population (including P5 females and P95 males). For the comfort assessment, a comparison was made between this shaped seat pan (shaped cushion) and a standard aircraft seat pan (flat cushion). Twenty-two internationalparticipants (11 males and 11 females, with BMI between 16 and 30) took part in the blind experiment assuming six different postures. Subjective data were gained from questionnaires, whose results showed that the shaped cushion is better in terms of perceived postural comfort. Also, 64% of participants chose the shaped cushion as a preferred cushion because it was more comfortable and suitable for the buttock shape. Objective data were gathered with a pressure mat, and results showed a higher contact area and lower mean pressure distribution for shaped cushion. Significant correlations were calculated between objective and subjective data with Spearman Correlation coefficients.Mechatronic DesignMaterials and Manufacturin
Use pressure data below seat cushions to evaluate comfort
No full textDuring a flight, passengers spend most of their time sitting in their seats. Studying the comfort and discomfort while passengers are sitting is helpful to improve the overall comfort during a flight. Pressure mats are commonly used in studies to collect pressure distribution in order to research sitting comfort. Different from most past studies, in which pressure mats are placed on the top of the cushions, the focus of this paper is to show the potential of placing pressure mat below the seat cushion. Three identical cushions differing in stiffness were prepared. The pressure distribution of 12 sitting postures was collected from 33 subjects both at the top as well as at the bottom of the foam in a randomized order. After sitting on each cushion, the participant was asked to leave the seat and complete a sitting comfort and discomfort questionnaire. The results show that the softest cushion got the highest rank in short-term comfort and lowest rank in short-term discomfort. The recorded pressure distributions both on the top and at the bottom of the foam can influence comfort and discomfort. This indicates the potential to use pressure distributions under the foam to evaluate the perceived comfort and discomfort in sitting, which might reduce the intrusive feeling of theparticipants in comfort studies.Mechatronic DesignMaterials and Manufacturin
Development of physical discomfort of airline pilots during prolonged sitting
No full textDiscomfort was recorded by 26 airline pilots during flight. Thirteen reported their discomfort during a long haul flight and 13 completed the questionnaires during short haul flights. Discomfort values increased with time to high values, but with a modest decrease towards the end of the flight. Most discomfort was reported in the low back area. For the short haul flights upper back values were high and for long haul flights the buttock showed high values.Materials and ManufacturingApplied Ergonomics and DesignDelft Design Innovation & ImpactMechatronic Desig
The influence of the angle of attack on passenger comfort
No full textThe angle of attack (AOA) of an airplane changes the direction of the gravitational force on passengers and thereby might influence passengers’ flying experience. However, the contribution of the AOA regarding comfort/discomfort is not fully explored. In this paper, we aim to fill this knowledge gap by identifying the relationships between the perceived comfort/ discomfort of passengers and the AOA of the plane during the take-off and climbing phases of a flight. Anexperiment is conducted in a Boeing 737 fuselage where 10 participants were recruited. Each participant experiences 3 setups of seats with different AOAs (3, 14 and 18 degrees) for 20 minutes, respectively. Participants were asked to complete several sets of questionnaires during each session, and their heart rate and the pressure on the seat and the backrest were recorded as well. Experiment results indicated that participants experienced 14-degree as the most comfortable angle with the lowest discomfort, which might be useful for airlines in setting up the take-off and climbingprocedure.Mechatronic DesignMaterials and Manufacturin
Exploring factors influencing visual comfort in an aircraft cabin
No full textVisual stimulus might influence comfort of passengers in air travel. For a better understanding of the visual comfort, it is crucial to identify the constructs of the visual stimulus in the cabin and the contributions of different elements. A two-step approach was adopted in this study where in the first step, several creative sessions were executed for exploring the effect of different elements in the cabin regarding their impact on visual comfort. To inspire the participants, all creative sessions were held in a Boeing 737 cabin where participants were free to explore and had an immersive experience. All identified elements in the creative session were collected and grouped to different categories, that is use as input for the second step, which is an online survey investigating a possible hierarchy of the impact of those categories of elements on visual comfort. Eight were summarized and the three most influential categories were lighting, colour and the space arrangement. These were significantly different from other categories, namely the seat shape, the pattern, the windows, accessories and existence of advertisements. Regarding the gender and the age of the participants, we did not find significant differences regarding the preferences.Mechatronic DesignMaterials and Manufacturin
On the objective assessment of comfort
No full textIn this paper, a literature study is presented on the types of objective measures that can contribute to the prediction of (dis)comfort, the feasibility of measuring those factors, and the potential of building a model based on them. Results indicate that in addition to subjective measurements, objective measures might help us to understand the process towards comfort or discomfort better, and some of them might be used as predictors in modelling comfort/discomfort.Mechatronic DesignMaterials and Manufacturin
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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