1,721,014 research outputs found
Predicting ride comfort with reclined seats
No full textReclined seats in transport suggest luxury and comfort, but a review of the literature revealed little study of how backrest inclination influences the discomfort caused by vibration of a seat or a backrest. This thesis seeks to advance understanding of the influence of backrest inclination on vibration discomfort and provides a model for evaluating vibration discomfort and metrics for optimising seats with different backrest inclinations.Vibration discomfort depends on the direction and location of vibration input to the body. Subjects used magnitude estimation to judge vibration magnitudes from thresholds of perception up to 2 ms-2 r.m.s. at the 11 preferred 1/3-octave centre frequencies from 2.5 to 25 Hz. The first two experiments determined absolute thresholds and discomfort with x-axis backrest vibration (Experiment 1) and z-axis backrest vibration (Experiment 2) with four backrest inclinations (0°, 30°, 60°, and 90° from vertical). The third experiment investigated discomfort with vertical seat pan vibration and five backrest conditions (no backrest and backrest inclined to 0°, 30°, 60°, and 90°). With x-axis vibration of the back, inclining the backrest had similar effects on thresholds and equivalent comfort contours. Thresholds increased at frequencies from 4 to 8 Hz with increasing inclination of the backrest. With inclined backrests, 40% greater magnitudes of vibration were required from 4 to 8 Hz, to cause discomfort equivalent to that with the upright backrest. Frequency weighting Wc in current standards predicted discomfort and perception of x-axis vibration of the upright backrest (0°) but weighting Wb was more appropriate for inclined backrests. Frequency weighting Wd was appropriate for both discomfort and perception of z-axis vibration of the back at all backrest inclinations. With vertical seat acceleration, the frequency of greatest sensitivity decreased with increasing vibration magnitude. Compared to an upright backrest, around the main resonance of the body the vibration magnitudes required to cause similar discomfort were 100% greater with 60° and 90° backrest inclinations and 50% greater with a 30° backrest inclination.The fourth experiment investigated whole-body vertical vibration on a rigid seat with no backrest and with four backrest inclinations. With an inclined backrest, discomfort caused by high frequency vibration increased at the head or neck but discomfort at the head or neck caused by low frequencies (5 and 6.3 Hz) reduced. With inclined backrests, the procedures in current standards overestimate overall discomfort at frequencies around 5 and 6.3 Hz but underestimate discomfort caused by frequencies greater than about 8 Hz.The final experiment investigated a model for predicting vibration discomfort with three compliant reclined seats. At each frequency, the measured seat dynamic discomfort, MSDD (the ratio of the vibration acceleration required to cause similar discomfort with a compliant seat and a rigid reference seat), was compared with seat effective amplitude transmissibility, SEAT value (the ratio of overall ride values with a compliant seat and a rigid reference seat using the weightings in current standards). The compliant seats increased vibration discomfort at frequencies around the 4-Hz resonance but reduced vibration discomfort at frequencies greater than about 6.3 Hz. The SEAT values provided appropriate indications of how the foam increased vibration discomfort at some frequencies but decreased vibration discomfort at other frequencies. Differences between the SEAT values and the measured seat dynamic discomfort are consistent with the need for different frequency weightings when the body is supported by an inclined backrest.An empirical model was evolved from the experiments for predicting vibration discomfort with reclined seats. It is concluded that reclining a backrest will tend to be detrimental at frequencies greater than about 10 Hz with greater discomfort in the head or neck induced by vibration of the backrest. At frequencies around 5 and 6.3 Hz, reclining a backrest can reduce discomfort
Equivalent comfort contours for whole-body vertical vibration: effect of backrest inclination
No full textThe inclination of a backrest may be expected to alter the vibration transmitted to the body and the associated vibration discomfort. This study examined the influence of backrest inclination on the discomfort arising from whole-body vertical vibration when sitting in a rigid seat with a backrest inclined at 0? (upright), 30?, 60? and 90? (recumbent). Equivalent comfort contours were determined over the frequency range from 1 to 20 Hz and over the magnitude range from 0.2 to 2.0 ms 2 r.m.s. relative to the discomfort caused by 8-Hz vertical vibration at 0.4 ms-2 r.m.s. When sitting with the backrest inclined to 60? or 90?, there was less discomfort around 5 and 6.3 Hz than when sitting with the upright backrest. Around 16 and 20 Hz there was greater discomfort when sitting with the backrest inclined to 30?, 60?, and 90? than when sitting with the upright backrest. The reductions in discomfort at the lower frequencies may be associated with increased postural support and changes in the biodynamic responses of the body when reclined. Increased transmission of vibration to the head may explain the greater discomfort at high frequencies when sitting reclined. It is concluded that different methods of vibration evaluation are appropriate when evaluating vibration with upright and inclined backrests
Discomfort caused by x-axis vibration of the back: effect of backrest inclination
No full textVibration of the back is a potential source of discomfort for car passengers, with vibration in the x-axis (i.e. fore-and-aft with an upright backrest) often dominant. This study investigated how vibration discomfort depends on both the frequency of x-axis backrest vibration and the inclination of the backrest. Twelve subjects seated with a rigid backrest inclined by 0, 30, 60, or 90 degrees rated the discomfort caused by x-axis backrest vibration at 11 frequencies (between 2.5 and 25 Hz) at 9 levels (from about 3 to 24 dB above the absolute threshold in 3 dB steps) relative to the discomfort caused by 0.15 ms-2 r.m.s. 8-Hz x-axis backrest vibration. The subjects also rated the discomfort caused by 9 levels of 8-Hz x-axis backrest vibration relative to the discomfort caused by 2.0 ms-2 r.m.s. 8-Hz x-axis (i.e. vertical) vibration of the hand. The vibration acceleration of the backrest required to cause discomfort tended to be least at 8 Hz with the upright backrest and at 10 or 12.5 Hz with the backrest inclined by 30?, 60?, or 90?. At frequencies from 4 to 8 Hz, about 30 to 40% less acceleration was required to cause discomfort with the upright backrest than with the inclined backrests. It is concluded that frequency weighting Wc is appropriate for predicting vibration discomfort caused by x-axis vibration of an upright backrest, but that another frequency weighting (e.g. Wb) would be more appropriate for inclined backrests
Predicting discomfort from whole-body vertical vibration when sitting with an inclined backrest
Full text linkCurrent methods for evaluating seat vibration to predict vibration discomfort assume the same frequency weightings and axis multiplying factors can be used at the seat surface and the backrest irrespective of the backrest inclination. This experimental study investigated the discomfort arising from whole-body vertical vibration when sitting on a rigid seat with no backrest and with a backrest inclined at 0? (upright), 30?, 60?, and 90? (recumbent). Within each of these five postures, 12 subjects judged the discomfort caused by vertical sinusoidal whole-body vibration (at frequencies from 1 to 20 Hz at magnitudes from 0.2 to 2.0 ms-2 r.m.s.) relative to the discomfort produced by a reference vibration (8 Hz at 0.4 ms-2 r.m.s.). With 8-Hz vertical vibration, the subjects also judged vibration discomfort with each backrest condition relative to the vibration discomfort with no backrest. The locations in the body where discomfort was experienced were determined for each frequency at two vibration magnitudes. Equivalent comfort contours were determined for the five conditions of the backrest and show how discomfort depends on the frequency of vibration, the presence of the backrest, and the backrest inclination. At frequencies greater than about 8 Hz, the backrest increased vibration discomfort, especially when inclined to 30?, 60?, or 90?, and there was greater discomfort at the head or neck. At frequencies around 5 and 6.3 Hz there was less vibration discomfort when sitting with an inclined backrest
Equivalent comfort contours for vertical seat vibration: effect of vibration magnitude and backrest inclination
Full text linkThis study determined how backrest inclination and the frequency and magnitude of vertical seat vibration influence vibration discomfort. Subjects experienced vertical seat vibration at frequencies in the range 2.5 to 25 Hz at vibration magnitudes in the range 0.016 to 2.0 ms^-2 r.m.s. Equivalent comfort contours were determined with five backrest conditions: no backrest, and with a stationary backrest inclined at 0 degree (upright), 30, 60 and 90 degree. Within all conditions, the frequency of greatest sensitivity to acceleration decreased with increasing vibration magnitude. Compared to an upright backrest, around the main resonance of the body, the vibration magnitudes required to cause similar discomfort were 100% greater with 60-degree and 90-degree backrest inclinations and 50% greater with a 30-degree backrest inclination. It is concluded that no single frequency weighting provides an accurate prediction of the discomfort caused by vertical seat vibration at all magnitudes and with all backrest conditions.Practitioner Summary: Vertical seat vibration is a main cause of vibration discomfort for drivers and passengers of road vehicles. A frequency weighting has been standardised for the evaluation of vertical seat vibration when sitting upright but it was not known whether this weighting is suitable for the reclined sitting postures often adopted during travel
MUSIK IRINGAN TARI KREASI PAKARENA MA’LINO KARYA BASRI B. SILA DI SANGGAR SENI BATARA GOWA
Full text linkABSTRAK
Padil Fitra, 2018.Musik Iringan Tari Kreasi Pakarena Ma’Lino Di Sanggar Seni
Karya Basri B. Sila di Sanggar Seni Batara Gowa.
Penelitian ini bertujuan untuk mengetahui: 1) Bagaimana bentuk ragam
musik iringan tari kreasi pakarena ma’lino karya Basri B. Sila di Batara Gowa.2)
Bagaimana struktur musik iringan tari kreasi pakarena ma’lino karya Basri B. Sila
di Batara Gowa. Penelitian ini bersifat deskriptif kualitatif yaitu jenis penelitian
yang bertujuan untuk mengangkat fakta, keadaan, dan fenomena-fenomena yang
dialami Basri B. SilaMetode yang digunakan dalam penelitian ini adalah metode
wawancara bebas dan terbuka. Penelitian ini menghasilkan data deskriptif berupa
kata-kata tertulis atau lisan dari orang-orang selaku narasumber serta perilaku
yang diamati.Hasil dari penelitian ini adalah Pengolahan data menggunakan
metode analisis kualitatif nn statistik. Dari hasil penelitian dapat disimpulkan: 1)
Bentuk penyajian musik iringan tari kreasi Pakarena Ma’lino yaitu meliputi
penari perempuan yang berjumlah4 orang penari dengan bagian-bagian gerak
yang meliputi 7 ragam gerak yang meliputiI. A’jappa biring kassi (jalan
menyusuri pantai) II. An’dalekang (menjamu atau melayani para tamu) III.
Bombang An ggalura IV. Anyungke (Membuka) V. Ma’lino (Membumi) VI.
Anjaga Lino (Menjaga dunia) VII. Appala Kanga (Pamit). 2) StrukturMusik
iringan tari kreasi pakarena ma’lino terdiri dari tunrung pakanjara, tumbu appa’,
tunrung pappadang (tunrung appa’, tunrung tallu leko’ boddong, royong dan
tumbu pangallakkang)
The vibration of inclined backrests: perception and discomfort of vibration applied normal to the back in the x-axis of the body
Full text linkThe vibration of backrests contributes to the discomfort of drivers and passengers. A frequency weighting exists for evaluating the vibration of vertical backrests but not for reclined backrests often used during travel. This experimental study was designed to determine how backrest inclination and the frequency of vibration influence perception thresholds and vibration discomfort when the vibration is applied normal to the back (i.e. fore-and-aft vibration when seated upright and vertical vibration when fully reclined). Twelve subjects experienced the vibration of a backrest (at each of the 11 preferred one-third octave centre frequencies in the range 2.5–25 Hz) at vibration magnitudes from the threshold of perception to 24 dB above threshold. Initially, absolute thresholds for the perception of vibration were determined with four backrest inclinations: 0° (upright), 30°, 60° and 90° (recumbent). The method of magnitude estimation was then used to obtain judgements of vibration discomfort with each of the four backrest angles. Finally, the relative discomfort between the four backrest angles, and the principal locations for feeling vibration discomfort in the body, were determined. With all backrest inclinations, absolute thresholds for the perception of vibration acceleration were dependent on the frequency of vibration. As the backrest inclination became more horizontal, the thresholds increased at frequencies between 4 and 8 Hz. For all backrest inclinations, the rate of growth of discomfort with increasing magnitude of vibration was independent of the frequency of vibration, so the frequency-dependence of discomfort was similar over the range of magnitudes investigated (0.04–0.6 m s?2 rms). With an upright backrest, the discomfort caused by vibration acceleration tended to be greatest at frequencies less than about 8 Hz. With inclined backrests (at 30°, 60°, and 90°), the equivalent comfort contours were broadly similar to each other, with greatest discomfort caused by acceleration around 10 or 12.5 Hz. At frequencies from 4 to 8 Hz, 30–40 percent greater magnitudes of vibration were required with the three inclined backrests to cause discomfort equivalent to that caused by the upright backrest. It is concluded that with an upright backrest the frequency weighting Wc used in current standards is appropriate for predicting the discomfort caused by fore-and-aft backrest vibration. With inclined and horizontal backrests, a weighting similar to frequency weighting Wb (used to predict discomfort caused by vertical seat vibration) appears more appropriate
The vibration of inclined backrests: perception and discomfort of vibration applied parallel to the back in the z-axis of the body
Full text linkThis study determined how backrest inclination and the frequency of vibration influence the perception and discomfort of vibration applied parallel to the back (vertical vibration when sitting upright, horizontal vibration when recumbent). Subjects experienced backrest vibration at frequencies in the range 2.5 to 25 Hz at vibration magnitudes up to 24 dB above threshold. Absolute thresholds, equivalent comfort contours, and the principal locations for feeling vibration were determined with four backrest inclinations: 0° (upright), 30°, 60° and 90° (recumbent). With all backrest inclinations, acceleration thresholds and equivalent comfort contours were similar and increased with increasing frequency at 6 dB per octave (i.e. velocity constant). It is concluded that backrest inclination has little effect on the frequency dependence of thresholds and equivalent comfort contours for vibration applied along the back, and that the W d frequency weighting in current standards is appropriate for evaluating z-axis vibration of the back at all backrest inclinations.Statement of Relevance: To minimise the vibration discomfort of seated people, it is necessary to understand how discomfort varies with backrest inclination. It is concluded that the vibration on backrests can be measured using a pad between the backrest and the back, so that it reclines with the backrest, and the measured vibration evaluated without correcting for the backrest inclination
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