368 research outputs found
The chemical modification of tropical wood polymer composites
No full textWood polymer composites were manufactured from several types of tropical wood species by impregnating the woods with acrylonitrile monomer solution. The physical and mechanical properties of wood polymer composites were then investigated in this study. The vacuum-pressure method was employed to impregnate wood samples with monomer and in situ polymerization. Acrylonitrile reacted and incorporated with wood, which was confirmed through Fourier transform infrared spectroscopy and scanning electron microscopy test analysis. The mechanical properties of wood samples in terms of modulus of elasticity and compressive modulus were found to be improved on acrylonitrile treatment. Besides, the fabricated wood polymer composite samples had lower water absorption and higher surface hardness (Shore D) value as compared to their corresponding raw one. For wood polymer composites, a significant improvement was found in physical and mechanical properties compared to the raw woods.Md. Saiful Islam, Sinin Hamdan, Azman Hassan, Zainal Abidin Talib, and HR Sobu
Audio-based approaches in tuning retrieval of gamelan ensemble
No full textPreliminary studies on gamelan instruments namely bonang, peking and kenong discussed in this work focus on their physical structure, tunings, and sound production. Since sound descriptions can only be measured by listening and are at the discretion of the creator, this work discusses about how to distinguish gamelan frequencies in a signal and the time-localized frequency content for each tone at a given time. This study focuses on the audio-based approach to tuning retrieval where the fundamental and overtone pitch is shown at all frequencies at a given time using Fourier transform, spectra, spectromorphology, and spectrograms. Three approaches used in retrieving tunings of gamelan are as follows: chladni patterns experiment using fine particle (sand), acoustic excitation from speaker for non-contact sinusoidal acoustic excitation and non-contact laser detector at specific eigen frequency, electronic speckle pattern interferometry (espi) for coherent addition of speckle fields diffracted by object and reference fields and laser doppler vibrometer (LDV) captured the vibration of the eigen frequency from the gong. Picoscope Melda analyser and Adobe using voltage-based triggers generate fast fourier transform (FFT) producing a spectrum, the decay signal is used for Q (loss factor) calculation. This study compares the harmonic, pitch, and size of bonang. The tone of peking was investigated using time-frequency analysis (TFA). Melda analyzer proved that all peking sustained the initial fundamental frequency and overtone at t=0 until 2s. This work also looks into timbral visualization of bonang. The bonang's sound profile has distinct characteristics, indicating a high recognition rate. The spectrogram revealed a simple fundamental frequency indicated by the brightest colours. The Q factor indicates the long-term viability or rapid decay. This research shows some of the preliminary findings and challenges associated with the analysis of the acoustic properties of selected gamelan instruments. When listening to its tones in a musical environment, individual harmonics of a complex tone and partial identification may be nearly impossible to discern by the human ear. The method of temporal localization on the dominant frequency at its unique time for each tone allows
for the detection of frequencies present in the signal. According to this research, one gamelan's intonation, tone, and sentiments will always differ from another gamelan's. As a result, it proved that these primitive methods may provide tuning to the gamelan set. Field trips to the Jogjakarta gamelan builders reveal that the gamelan tuner solely tuned the gamelan based on hearing, which is passed down from generation to generation. The maker's intuition permits him to create a specific 'signature' through sound that is unique to a given gamelan set
Timbral Spectogram of The Bonang From Malaysian Gamelan
No full textThis study explores timbral visualization to recognize the sound from Malaysian Gamelan and provide detailed description of the sound.The timbre of two sets of bonang (bonang penerus and bonang barung ) are used to perceive the sound recorded from the Malaysian Gamelan. The higher
pitch bonang penerus are smaller in size than the bonang barung . The bonang panerus plays a part that is similar to the bonang barung with frequency twice as bonang barung .The timbral characteristics can precisely and objectively describes the sound characteristics of aboning that was always faced by ethnomusicologists in field work activities. The sound profile from each set of boning shows different characteristics which indicate that the recognition process showed a high recognition rate. From the finding bonang penerus showed a clear fundamental frequency indicated by the brightest colors’ in the spectrogram (yellow and red). Bonang barung showed a strong attack and decay rapidly.The sustainability or the rapid decay is also indicated by the Q factor.Q factor for bonang penerus range from 20.20 to 23.87 whereas the Q factor for bonang barung is slightly small from 12.70-17.00
Thermal and decay-resistance properties of tropical wood-plastic composites
No full textThis investigation concerns about the thermal and decay resistance properties of tropical wood polymer composites. Wood polymer composites were prepared from several types of tropical wood species by impregnating the woods with ethyl methacrylate that was combined with a cross-linker, hexamethylene diisocyanate. Thermal properties of wood polymer composites in terms of thermogravimetric analysis and differential scanning calorimetry were evaluated, and an improvement in thermal stability was found on ethyl methacrylate and ethyl methacrylate–hexamethylene diisocyanate treatment. A significant improvement in decay resistance was also identified in wood polymer composites that were treated with ethyl methacrylate, and also, with ethyl methacrylate–hexamethylene diisocyanate. The improvement in properties was observed as more potential with ethyl methacrylate–hexamethylene diisocyanate combination rather than ethyl methacrylate.Md Saiful Islam, Sinin Hamdan, Habibur Rahman Sobuz, Rezaur Rahman and Abu Saleh Ahme
Mechanical Properties of Concrete with Clam Shell Powder (CSP) as Partial Cement Replacement.
No full textThis research focuses on compressive strength of concrete containing different percentages of municipal waste clam shell powder (CSP). The amount of cement is replaced by 5%, 10% and
15% of CSP. The result obtained shows that the compressive strength increases with the CSP content. Concrete containing 15%CSP has lower compressive strength compared to those containing 5% and 10%CSP. The concrete containing 15%CSP is almost similar to the control concrete (with zero CSP)
Mechanical properties of concrete with clam shell powder (csp) as partial cement replacement
No full textThis research focuses on compressive strength of concrete containing different percentages of municipal waste clam shell powder (CSP). The amount of cement is replaced by 5%, 10% and 15% of CSP. The result obtained shows that the compressive strength increases with the CSP content. Concrete containing 15%CSP has lower compressive strength compared to those containing 5% and 10%CSP. The concrete containing 15%CSP is almost similar to the control concrete (with zero CSP)
The thermomechanical properties of aromatic polymers
No full textHigh performance aromatic polymers such as PEEK and PEK are widely
used in composite and related applications. However, their high rate
thermomechanical properties are not well understood. This thesis
describes a series of investigations into their mechanical behaviour over
a large range of strain rates (10-3 -103 s-1
) and temperatures (20-200°
C) which were carried out in order to more fully understand their
properties and to assess the applicability of standard polymer property
models to their behaviour. The experiments involved the design and
construction of two novel sets of high rate test apparatus. These were a
cross-bow based system which enabled high strains to be obtained at
strain rates of 103 s-1 and a drop-weight system based around a high
speed camera which enabled direct measurements of radial strain and
observation of sample behaviour to take place. The cross-bow apparatus
incorporated a laser-photodiode system to enable direct strain
measurements to be made and thus had an advantage over
conventional Hopkinson bars of direct, rather than derived, strain
measurements with a sufficiently energetic projectile to produce large
deformations. These systems were used in addition to standard
hydraulic ram and dropweight equipment. A heater unit to enable tests to
be carried out over the desired temperature range was also designed
and constructed and used with all the above systems.
A comprehensive set of Differential Scanning Calorimetry and X-ray
tests were carried out on samples before and after mechanical testing in
order to provide structural data to aid the interpretation of the mechanical test result
Sound Absorption Coefficients Natural Fibre Reinforced Composites
No full textIn this Investigation, the influence of two kind of polymers (Urea-formaldehyde and
Polypropylene) mixed with natural fibre (Kenaf) were studied for their sound absorption coefficients.
Four samples were made; Samples A1 and A2 are made of Kenaf core fibre with adhesive of high
emission Urea-formaldehyde resin (HN 100) with 51.6 % solid content. The fabrication of the particle
board was done using a hot press for 6 minutes under the pressure of 40 Ton at 1800C for different
fibre lengths 1 mm (Sample A1) and 0.6 mm (Sample A2) with weight fraction of 80%. Sample B1
and B2 are made of Kenaf core fibre with polypropylene matrix materials with coupling agent of
polyvinyl alcohol. The fabrication of the sample was done using hot press for 30 minutes under the
pressure of 1000 Psi at 1800C for different lengths of 1 mm (Sample B1) and 0.6 mm (Sample B2)
with weight fraction of 20%. The sound absorption coefficients of samples were measured according
to American society for Testing Materials (ASTM E1050 10) two microphone method. It is evident
that type of polymer influences the sound absorption coefficients
The thermomechanical properties of aromatic polymers
No full textSIGLEAvailable from British Library Document Supply Centre- DSC:DX186922 / BLDSC - British Library Document Supply CentreGBUnited Kingdo
The strain-rate and temperature dependence of the mechanical properties of polyetherketone and polyetheretherketone
No full textABSTRACT The mechanical properties of polyetheretherketone and polyetherketone were studied as a function of strain rate and temperature in the ranges 10⁻3 to 103s⁻1 and 20–200°C. At temperatures below the glass transition temperature, Tg, the strain-rate sensitivity of both polymers was found to be almost independent of temperature with a value of ̴4 MPa per decade of strain rate and the behaviour was well described by an Eyring relationship leading to an activation volume of ̴1 nm3. Above Tg, X-ray and differential scanning calorimetry studies show that cold-crystallization phenomena play a very important part in the polymer behaviour, leading to an increase of yield stress with increasing temperature. The crystallization was found to be highly strain-rate dependent with no increase in crystalline content occurring in quasi-static tests and increases of up to 20% in higher rate tests. Much of the data have been gathered using novel test equipment which is described in the paper
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