Mechanical Engineering

Coir fiber from coconut husk is an important agricultural waste in Malaysia. The porous structure of fiber makes it an eligible material for acoustical absorption. In previous studies at Universiti Kebangsaan Malaysia, single layer coir fiber showed low acoustical absorption in medium and low frequencies; e.g. absorption coefficient of a 20 mm industrial prepared coir fiber sample was below 0.3 for frequencies less than 1.5 kHz. Current research was initiated to improve the shortcoming by mixing industrial prepared coir fiber with air gap layers. Analyzes were based on two approaches, namely; Delany-Bazley with acoustic transmission analysis (ATA) and Allard elastic model with transfer matrix analysis. Experimental measurements were conducted in impedance tube to validate the analytical results. Outcomes described that Delany-Bazley-ATA technique was an approximate solution showing overall absorption path without giving any accurate information about the peaks and resonances. Allard method took the elasticity of material into account and transfer matrices were able to characterize the whole structure as a combination of single layers. Results were close to experimental values and predicted the path and resonances very well. Further analyzes were conducted by Allard method and derived that having a fiber layer backed by an air gap was better than leaving the same gap in between that layer. The explanation was that, in the first arrangement, the sound field impacted a solid layer with higher thickness and followed a longer transmission path which caused a higher acoustical absorption. Furthermore, it was noticed that a reasonable thickness of backing air gap improved the overall sound absorption. Increase in the gap thickness produced more peaks and moved them to lower frequencies which caused better absorption in low frequencies. The cause of this phenomenon was increase in impedance of the panel due to rise in the air-gap thickness. This moved the acoustical resonances to lower frequencies and improved the sound absorption in this frequency span. Finally, it was concluded that other acoustic absorption ¶ Present address: Acoustics, Vibration and Controls Group, School of Mechanical Engineering, The University of Adelaide, SA 5005, Australia.

Quality and Quantity (Q&Q) of researches is one of the relevant criteria in the assessment of research university
(RU) and this can be seen through the status of publication in a certain universities (number of the publication in
indexed journal and citation). The main purpose of writing and publishing is to publicize research findings and
share knowledge gained with other researchers in their respective fields of research. Research quality can be
indicated by index database ISI WOS and SCOPUS and also impact factor which refers to terms and quotes
(citation). Principles and standards for quality research design are can be determined in texts, reports, essays and
guides to research design and methodology. Quantity of research is evaluated by the amount of indexed journals
with impact factor. This suggests that achieving only one or two stands is typically insufficient to assert quality.
Researcher work has value when it is judged by peers to have merit sufficient for acknowledgement in a new text
article. By the way, a specific standard that will ensure quality research, the more research studies are aligned
with or respond to these principles, the higher the quality of research. This paper discusses the strategy that can
be applied to maximize journal publication by means of stimulation technique. In the end of the study, we
analyze the student feedback on the quality in supervision towards achieving high quality in research for pure
and social science students.

Scientific writing is one of the utmost important thing in bench marking a postgraduate’s quality as an academic. This is where a good supervision plays its role in ensuring the success of this capability. Students regard their supervisor as the main source of information as well as mentors and role models. However if there is no mutual respect between supervisor and student, the outcome will not be that great either. Supervisor also needs to cultivate the principality of honesty and truthfulness in every student while conducting their research. There are four crucial research etiquette that students need to abide by which are confidentiality, writing, communication and on research itself. The achievement of a successful research supervision and a good relationship between a supervisor and student relies on four fundamental factors namely gender, citizenship, age and academic discipline. Based on the survey results, it was visible that students from different fields have different needs especially in requiring competent facilities and equipments in executing their research which shows a very high percentage agreeing to this of students from pure science background compared to students from social science background. Finally, there are a number of strategies that can be adopted by students to publish high quality writings such as mastering the English language and following the important writing steps meticulously. Most prestige international journals require the submitted articles to be written in English language and by following all the important writing steps, it will ensure that all the vital elements in a high quality writing have already been included.

Research and ethics are two words that will always link together. A good management is required to conduct a good research and a good research is the one that is highly-ethical. This study discusses the three types of research known are basic research, applied research and action research. There are several criteria that need to be met in order to come up with a high quality research which include the scientific quality and the scope to name a few. Ethical issues commonly encountered in research and how to achieve a high-impact result with little resource by implementing MDS (Multi-Dimensional Assessment) in the research are also addressed here.

Research is conducted to identify problems or to find answers to ‘uncertainties’. Studies are conducted because there is
uncertainty about a phenomenon that either has, or has not occured. Research also aims to use the best method to solve problems,
whether or not experiments are conducted. Meanwhile, the main purpose of writing and publishing is to disseminate research
findings and to share new knowledge with other researchers in their respective fields. The most important product that should be
highlighted is that the results of research should benefit the community. This paper collects some of the views of researchers who
are lecturers from Malaysian Higher Learning Institutes, who have been successful at the national and international levels and
who have produced high-quality publications. These views were obtained through interviews (face to face, phone and email) and
can be used as tools to motivate young researchers.

A university's strength is very much depending on the leadership of the professors as well as the passion of
young researchers. Their experience, expertise and spirit lead to the excellence of the university and as well as
the reputation. There is however a certain mature period for young lecturers to make them capable of doing a
quality research. The maturity denotes the readiness to conduct a proper reasearch and to carry other
responsibilities in providing a platform of contribution towards the university, society and Nation. Hence, they
have to be independent to utilise all resources in achieving their goals and target. This paperwork acts as a guide
to expedite their maturity by providing information to ensure the continuance of the research field. The proposal
of the study is based on the case study and brainstorming session through several workshop organised by
research group.

Coir fiber from coconut husk is an important agricultural waste in Malaysia. Acoustic absorption coefficient of the fiber as a porous material is studied in this paper. Two types of fiber are investigated, fresh from wet market and industrial prepared mixed with binder. Moreover two analytical models, namely; Delany-Bazley and Biot-Allard are used for analysis. Experimental measurements in impedance tube are conducted to validate the analytical outcomes. Results show that fresh coir fiber has an average absorption coefficient of 0.8 at f > 1360 Hz and 20 mm thickness. Increasing the thickness is improved the sound absorption in lower frequencies, having the same average at f > 578 Hz and 45 mm thickness. Delany-Bazley technique can be used for both types of fiber while Biot-Allard method is compensated for the industrial prepared fiber considering the binder additive. This form generally shows poor acoustical absorption in low frequencies. Inevitably, fiber has to be mixed with additives in commercial use to enhance its characteristics such as stiffness, unti-fungus and flammability. Hence other approaches such as adding air gap or perforated plate should be used to improve the acoustical properties of industrial treated coir fiber.

Coconut is one of the most important harvests in Malaysia. Industrial prepared coir fiber is obtained from coconut husk combined with latex and other additives to enhance its structural characteristics. Unfortunately, such inevitable process diminishes the acoustical features of material. Previous studies on industrial coir fiber and fiber-air gap layers showed that low frequency absorptions needed improvements. Therefore perforated plate (PP) was added to the multilayer structure to further enhance the sound absorption in this area. Analyses were accomplished through three PP modeling approaches (Allard, Beranek and Ver, Atalla and Sgard) and Allard Transfer Function (TF) method. Experiments were conducted in impedance tube to support the analytical results. Outcomes showed that Allard TF method was generally closer to measurement values and implemented for additional analyses. Two possible conditions of putting PP in front of fiber layer or between fiber-air gap layers were investigated. Both arrangements were suitable to enhance the sound absorption. Although, when PP was backed by coir fiber and air gap, porosity of the plate had great influence in adjusting the amount of low frequency absorption. Result derived that PP might improve the low frequency absorption of coir fiber but at the same time the medium frequency absorption was reduced. This effect was noticed previously in coir fiber-air gap structures while the air gap thickness increased. The advantage of using PP was that it assisted in greatly reducing the air gap thickness under the same acoustical performance. Hence it is an efficient tool to reduce the thickness of acoustic isolators in practical purposes.

Exposure to vibration has various physiological effects on vehicle passengers. Engine is one of the main sources of vehicle vibration. The major causes of engine vibration are combustion forces transmitted through the pistons and connection rods. Evaluation of sources is the first step to attenuate this vibration. Assessment of these sources is not an easy task because internal parts of machinery are not accessible. Often, instrumentation for such systems is costly, time consuming and some modifications would be necessary. Aim of the first part of this paper was to validate an inverse technique and carry out mobility analysis on a vehicle crankshaft to achieve matrix of Frequency Response Functions (FRFs). Outcomes were implemented to reconstruct the applied force for single and multiple-input systems. In the second part, the validated inverse technique and FRFs were used to estimate piston forces of an operating engine. Bearings of crankshaft were chosen as nearest accessible parts to piston connecting rods. Accelerometers were connected to the bearings for response measurement during an ideal engine operation. These responses together with FRFs, which were estimated in the previous part, were utilised in the inverse technique. Tikhonov regularization was used to solve the ill-conditioned inverse system. Two methods, namely L-curve criterion and Generalized Cross Validation (GCV), were employed to find the regularization parameter for the Tikhonov method. The inverse problem was solved and piston forces applied to crankpins were estimated. Results were validated by pressure measurement inside a cylinder and estimating the corresponding combustion force. This validation showed that inverse technique and measurement outcomes were roughly in agreement. In presence of various noise, L-curve criterion conduces to more robust results compared to the GCV method. But in the absence of high correlation between sources (f4600 HzHz), the GCV technique leads to more accurate results. This research shows that inverse techniques have great ability to estimate vibration sources inside the machinery.

Noise has various effects on comfort, performance and health of human. Sound are analysed by human brain based on the frequencies and amplitudes. In a dynamic system, transmission of sound and vibrations depend on frequency and direction of the input motion and characteristics of the output. It is imperative that automotive manufacturers invest a lot of effort and money to improve and enhance the vibro-acoustics performance of their products. The enhancement effort may be very difficult and time-consuming if one relies only on 'trial and error' method without prior knowledge about the sources itself. Complex noise inside a vehicle cabin originated from various sources and travel through many pathways. First stage of sound quality refinement is to find the source. It is vital for automotive engineers to identify the dominant noise sources such as engine noise, exhaust noise and noise due to vibration transmission inside of vehicle. The purpose of this paper is to find the vibro-acoustical sources of noise in a passenger vehicle compartment. The implementation of spectral analysis method is much faster than the 'trial and error' methods in which, parts should be separated to measure the transfer functions. Also by using spectral analysis method, signals can be recorded in real operational conditions which conduce to more consistent results. A multi-channel analyser is utilised to measure and record the vibro-acoustical signals. Computational algorithms are also employed to identify contribution of various sources towards the measured interior signal. These achievements can be utilised to detect, control and optimise interior noise performance of road transport vehicles. although some deviations from the real model affected the result. For a stationary vehicle, sources of noise emissions inside the compartment are divided into two categories:

Coir fiber from coconut husk is an important agricultural waste in Malaysia. The porous structure
of fiber makes it an eligible material for acoustical absorption. In previous studies at Universiti
Kebangsaan Malaysia, single layer coir fiber showed low acoustical absorption in medium and low
frequencies; e.g. absorption coefficient of a 20mm industrial prepared coir fiber sample was below
0.3 for frequencies less than 1.5 kHz. Current research was initiated to improve the shortcoming by
mixing industrial prepared coir fiber with air gap layers. Analyzes were based on two approaches,
namely; Delany–Bazley with acoustic transmission analysis (ATA) and Allard elastic model with
transfer matrix analysis. Experimental measurements were conducted in impedance tube to validate
the analytical results. Outcomes described that Delany–Bazley-ATA technique was an approximate
solution showing overall absorption path without giving any accurate information about the peaks
and resonances. Allard method took the elasticity of material into account and transfer matrices
were able to characterize the whole structure as a combination of single layers. Results were close
to experimental values and predicted the path and resonances very well. Further analyzes were
conducted by Allard method and derived that having a fiber layer backed by an air gap was better
than leaving the same gap in between that layer. The explanation was that, in the first arrangement,
the sound field impacted a solid layer with higher thickness and followed a longer transmission
path which caused a higher acoustical absorption. Furthermore, it was noticed that a reasonable
thickness of backing air gap improved the overall sound absorption. Increase in the gap thickness
produced more peaks and moved them to lower frequencies which caused better absorption in low
frequencies. The cause of this phenomenon was increase in impedance of the panel due to rise in
the air-gap thickness. This moved the acoustical resonances to lower frequencies and improved the
sound absorption in this frequency span. Finally, it was concluded that other acoustic absorption techniques such as adding perforated plate may be combined with coir fiber-air gap structure to
improve the low frequency acoustic absorption coefficient without any need to highly increase the
air gap thickness.