An analysis of the power spectral density of ultra-wideband (UWB) signals is presented in order to evaluate the effects of cumulative interference from multiple UWB devices on victim narrowband systems in their overlay bands like WiFi (i.e. IEEE802.11a) and 3rdG systems (Universal mobile telecommunications system/wideband code division multiple access). In this paper, the performances are studied through the bit-error-rate as a function of signal-to-noise ratio as well as signal-to-interference power ratio using computer simulation and exploiting the realistic channel model (i.e. modified Saleh-Valenzuela model). Several modifications of a generic Gaussian pulse waveform with lengths in the order of nanoseconds were used to generate UWB spectra. Different kinds of pulse modulation (i.e. antipodal and orthogonal) schemes were also taken into account.
The aim of this work was to investigate the effect of glycerol concentration on mechanical
and physical properties of gellan gum (GG) biofilm. The biofilm was prepared using solvent
casting method and the effective glycerol concentration was found to be within 30-50%
w/w (based on GG weight). At 60 and 70 w/w% of glycerol, the films started to distort
because the films was flexible and brittle. As glycerol concentration was increased the tensile
strength (TS) and Youngs modulus (E) of films decreased. Somehow, elongation at break
(EAB), water vapor transmission rate (WVTR) and swelling of films was increased. Glycerol
plasticized GG biofilm was thermally stable and flexible, proposed its can be exploited as
film-forming material and with optimized glycerol concentration it has good mechanical and
physical properties for edible biofilm.
The human brain generates different oscillations at different frequencies during various consciousness levels. When these brain waves synchronize with exogenous rhythmic stimulation, the brain experiences strong, yet relaxing emotion that could be involved in the formation of memory. We investigated the character of rhythmic oscillatory dynamics by electroencephalography (EEG) of subjects listening to a short verse of the Holy Quran compared to resting and Arabic news listening. The mean power amplitudes of each frequency band for wavelet-based time-frequency analysis were obtained from 5000 ms of segmented EEG recordings during rest, news and Quran listening conditions. The time series analysis of power from each of three conditions in each frequency band from the grand averaged data was then subjected to autocorrelation study. The results showed significant cyclic overall trends of increasing and decreasing patterns of power in the low frequency brain wave oscillation of different head regions especially global, frontal and temporal sites. These results provided a basis for prediction of the periodicity of the power of the oscillatory brain dynamics of delta and robustly in theta regions which occurred during Quran listening. Despite several limitations, our data offered a plausible scientific basis to the emotional induction during Quran listening that mimics recognized as data from music listening studies. This offered a promising perspective for future studies in translational neurophysiological, cognitive and biofeedback on Quran listening to modify brain behaviour in health and disease.
The main purpose of this study is to determine shoreline change in Bengkalis Cape, Riau Province, Indonesia using sediment samples analysis, satellite images, and oceanographic parameters. The samples were collected at five stations by using sediment grab and oceanographic observation was also carried out at each station in November 2015. The southern part of Bengkalis Cape is characterised by fine-grain sediments (mud) and high rate of accretion that reaches 29.77 metre/year, and is influenced by weak tidal currents with a velocity of less than 0.06 m/s and low wave energy. In contrast, the northern part is occupied by coarse-grain sediments (sand) which is characterised by high rate of abrasion as shown in the image data for 20 years; 1995-2015 reaches 38.02 metre/year, and is under the influence of strong tidal current (0.16 m/s) and high wave energy. The major contributing factor for the shoreline change is the current system which flowing from Malacca strait to the shore area and sediments deposition in the area.
Current National Design Specification (NDS 2005) provides the guideline to design timber joints strengthened with steel fasteners. This study investigates the possibility of using NDS 2005 to estimate the load-carrying capacity of timber joints fastened with Glass Fibre Reinforced Polymer (GFRP) dowel. Double shear timber joint fastened with steel dowels were tested to validate the joints fastened with GFRP using 1.27 cm diameter dowels. Tests were also conducted to determine the dowel bearing strength of wood and dowel bending strength of GFRP and steel. The failure modes of all tests were observed and recorded. Results showed that NDS (2005) successfully estimated the failure mode and was capable of predicting the joint load-carrying capacity when fastened with a GFRP dowel and this was well validated by the load carrying capacity of a steel dowel.
Responses were recorded from normal healthy subjects and age-related macular degeneration (AMD) patients and evaluated, using a new variant of mfVEP. Subjects information was recorded using 64 EEG channels with a computer-based acquisition system. The stimulus layout was a 84 region corticallyscaled dartboard comprising 12 sectors and seven concentric rings subtending a diameter of 23º, presented dichoptically at 60 Hz. Data from the control and AMD patients were statistically compared when fitted concurrently into the multiple regression analysis. The Pattern-pulse mfVEP technique could distinguish between normal eyes and those with a definite diagnosis of dry and wet AMD when responses from the macula were considered.
The paper seeks to assuage the fears and worries over living modified organisms (LMOs). It describes how any research carried out on LMOs as well as any release activity on LMOs for public use in Malaysia is controlled by the Biosafety Act 2007. Stringent risk assessment of the LMO and its product/s is carried out to eradicate or minimize the negative effects of these on animal and human health, and to biological diversity and the environment. In contrast, no such risk assessment is carried out on introduced exotic species, or on the products of other types of technology, with the exception of pharmaceuticals. Examples are given comparing risk assessment on LMOs and exotic species.
The unsustainable harvesting of sea cucumbers in the Straits of Malacca poses a danger of collapsing population of this marine resource. Recent survey revealed the absence of commercially important sea cucumber species like Stichopus horrens was alarming since there were a lot of taxonomical complications in identifying species from this genus. The knowledge of taxonomy and ecology is an integral part in determining resource management strategies and conservation of marine resources like sea cucumber.
A monitoring procedure was introduced for process variability in a multivariate setting based on individual observations which was a combination of (i) robust high breakdown point approach in the set-up stage to determine the reference sample and (ii) the use of Wilks chart in the mass production stage. This setting is what the Malaysian manufacturing industry is currently lacking in, especially when a robust approach must be used. The advantage of this procedure was revealed by using the case of a female shrouded connector production process in a Malaysian industry. Moreover, this procedure could also be used in any process quality monitoring and for any industry. A recommendation for quality practitioners was also addressed.
Elevated temperature affects marine benthic algae by reducing growth and limits the transport of electron or carbon fixation which may reduce the ability of the cell to use light. This resulting excess light energy may cause photoinhibition. In this study, the photosystem II of the benthic microalgal communities from Casey, eastern Antarctic were relatively unaffected by significant changes in temperatures up to 8ºC, along with high PAR level (450 μmol photons m–2 s–1). Similarly, the community was able to photosynthesize as the temperature was reduced to –5ºC. Recovery from saturating and photoinhibiting irradiances was not significantly influenced by temperatures at both –5ºC and 8ºC. These responses were consistent with those recorded by past experiments on Antarctic benthic diatoms and temperate diatoms which showed that climate change did not have a significant impact on the ability of benthic microalgae to recover from photoinhibitory temperature stress.
An optical code generating device for a portable optical access-card system was constructed using the plastic optical fibre (POF) waveguide coupler. The newly constructed device provided output light intensities which were used as optical codes in a portable optical access-card system. The construction of a basic 1 × 2 waveguide design combined two major components which were the asymmetric Y-junction splitter and the linear taper. A hollow waveguide structure was utilized as it provided more flexibility in guiding light rays. A basic 1 × 2 waveguide coupler was designed using the CAD tool and then the ray was traced using the non-sequential ray tracing tool. A linear relationship between the tap-off ratio and the waveguide tap-width enabled a higher-level hollow waveguide coupler to be designed using the simple cascading technique. Construction of a 1 × 4 and higher level waveguide coupler was easily realized using the basic 1 × 2 waveguide coupler design together with a simple cascading technique.
Spatio-temporal datasets are a collection of datasets where data can vary in both space and time. Theoretically, such datasets can be considered as continuous and discrete. For example, specification of the function, F: Ed T Rn, where Ed denotes d-dimensional Euclidean space, T = R* ∩ {} the domain of time and Rn an n-dimensional scalar field. Examples of such data sets include time-varying simulation results, film and videos, time-varying medical datasets, geometry models with motion or deformation, meteorological measurements, and many more. It is therefore highly desirable to use visualisation to summarize meaningful information in higher dimensional spatio-temporal datasets. Our aim is to conceive an efficient visual study to facilitate scientists in identifying temporal association among complex and chaotic atom movements in ion trajectories. An application that uses a streamline for spatial motion of ion trajectories and Colour Number Coding Scheme for temporal encoding of high degree of timeline events among mobile ions is proposed. With an anthology of the visual examples, it was revealed that this application would be beneficial for scientists to visually mine any 3D spatio-temporal dataset.
Orthogonal Frequency Division Multiplexing (OFDM) is a successful technique in wireless communication systems. Frequency offset in the OFDM system leads to loss of orthogonality among subcarriers which results in the occurrence of intercarrier interference (ICI). To improve the efficiency of bandwidth performance in the ICI self-cancellation scheme, frequency domain partial response signaling (PRS) was investigated. In this study, the integer polynomial partial response coefficients were exploited to enhance carrier-to-interference power ratio (CIR) in the OFDM system. CIR was enhanced up to 4.1 dB to 5 dB when the lengths of PRS polynomial, K was 2 and 5, respectively.
A survey on the diversity of marine macrogastropoda
in Pulau Songsong, Pulau Bidan and Pulau Telor on the
Northern Straits of Malacca was conducted. Specimens
were collected on rocky shores following NaGISA protocol
and the number of marine macrogastropod were recorded.
Distances and the number of the same species were
converted into Relative Abundance unit (individuals per
100 m2
). A total of 15 species of marine macrogastropoda
were found from seven families namely Neritidae,
Trochidae, Ceriitidae, Littorinidae, Turbinidae, Muricidae
and Potamididae. Seven macrogastropoda species were
newly recorded from these three islands. Morula marginatra
was the most dominant species and Pulau Songsong had
the highest genera and species diversity among the three
islands. (Copied from article).
Radiation pre-vulcanised natural rubber latex (RVNRL) prepared by using gamma irradiation technique has many advantages over the conventionally prepared sulphur pre-vulcanised natural rubber latex (SPVL). Despite the fact that many potential latex dipped products can be made from RVNRL, little effort was made to fully commercialise the products because of the inferior strength of RVNRL products compared to SPVL products. An attempt was made to improve the tensile strength of RVNRL by combining both radiation and peroxide vulcanisation in order to ensure that the products will not tear or fail, and has sufficient stretch. Hexanediol diacrylate (HDDA) plays the main role as sensitizer during radiation vulcanisation and tert-butyl hydroperoxide (t-BHPO) as the co-sensitizer in peroxide vulcanisation. Pre-vulcanised natural rubber latex dipped films via hybrid radiation and peroxidation vulcanisations obtained showed tensile strength of 26.7 MPa, an increment of more than 15% compared to controlled film (22.5 MPa). Besides, the crosslink percentage of the rubber films also showed around 5% increment from 90.7% to 95.6%.
Since its invention, polyimide (PI) has been widely used in micro-electro-mechanical system (MEMS) devices. For fabrication, the PI membrane, PI-2723 HD-Microsystems was used as the membrane material due to its Young's modulus of 2.7 GPa and its film thickness could easily be controlled by changing the speed of the spin coater system. The application PI as membrane structure on silicon wafers therefore gave a much better mechanical performance then conventional membranes made of silicon dioxide (SiO2) or silicon nitride (Si3N4) layers. The fabrication of PI membrane was the same as for SiO2 and Si3N4 membranes; the basic step was to etch a side of the silicon wafer using wet anisotropic etching. This paper proposes an effective process for fabrication of PI membrane with f ast and little supervision. In this process, a dual step process was wet anisotropic etching of single crystal silicon using pottasium hydroxyl (KOH) with different concentrations and temperature processes. For the first process, 45% KOH under boiling temperature was used to etch at least 90%–95% of the silicon. In the second process, the silicon was submerged in 45% KOH with temperature at 70ºC–80ºC to etch away the residual silicon until a clean and transparent PI membrane was achieved. Using this method, the fabrication of PI membrane could be generated fast.
Katabatic winds dramatically affect the polar climate. Their activity depends on density of air and temperature in the source region. This paper presents for first time an analysis of the precipitable water vapour (PWV) variability and its relation to a katabatic event at Scott Base station, Antarctica. A significant effect in their characteristics toward calculation of a reliable user accuracy in GPS applications is addressed. Our investigations using the data between 21st and 30th of November 2002 showed that the PWV profile exhibited an irregular pattern with a maximum value of 7.38 mm (~ 6 mm on average), and was more strongly influenced by relative humidity than by wind speed activity. The dominant wind flow during this period was from the North-Northeast (blowing from the Ross Sea) with a median speed of 4.96 ms–1. The PWV was high when the temperature was between –15ºC and –11ºC. During the dates identified as a katabatic event between 21:30 UT of 28th November and 18:40 UT on 29th November, the wind blew from the Southeast-South direction (from the Ross Ice Shelf) with a maximum speed of 10.92 ms–1. The PWV increased ~1.4 mm (23%) from the mean value, indicating severe wind during this event which had pronounced effect on GPS observations.
A study to determine the impact of leachate from operating and closed landfills into the surface water and groundwater systems in the state of Selangor was conducted in the year 2009. Groundwater was a major source of water for various uses in Selangor, Malaysia and was especially important for industrial purposes. The presence of high numbers of landfill sites was seen to have increased the risk of groundwater contamination. There were 20 landfill sites in the state of Selangor and seven of them were still operating and 13 closed. The landfills are classified into four categories, which were: (a) landfills operating at critical stages without controls to prevent pollution into the environment; (b) open dumpsites that have the capacity to continue to accept waste but needed to be upgraded to manage leachate and gas; (c) landfills that were closed but no safety closure plan was carried out; and (d) engineered landfills with up to date technologies. As most of the landfills were built prior to 1989, they were not subjected to the Environmental Impact Assessment requirements, hence, they were being poorly managed and were badly sited. The non-engineered sites had no proper pollution controls such as cover materials, liner materials, groundwater monitoring wells, leachate collection ponds and treatment, and methane gas collection pipes. This study revealed that the surface water and groundwater at and nearby the landfill sites were contaminated at various levels due to the landfill sites and operation. A comparison between the current quality of surface water and groundwater with their respective standards and background levels was carried out to survey the trend of the contamination. However, the limited financial resources hindered a very thorough investigation and restricted the number of samples collected and parameters analysed.
Nowadays, the wireless technology has become a lifestyle; even the children have their own
mobile phones, although they are categorized as high risk susceptible to health problems
due to radiation. Thus, the public exposure that stemmed from electromagnetic radiations
become public concern since studies have been done and the finding showed that the repetitive
and long term exposure may have adverse health effect. This study was conducted to
evaluate the exposure level at UMT and UniSZA campuses by measuring the electric field
strength. This measurement was conducted using omni-directional antenna below 4 GHz,
connected to spectrum analyzer. In this paper, the measured values are compared with
the previous study from several locations and then the spatial maps of exposure level are
developed. The result shows that high exposure level was recorded at UMT and UniSZA.
From this study, the findings may assist the Ministry of Health to monitor the public health
due to non-ionizing radiation (NIR) exposure. This is crucial to make sure the international
commission of non-ionizing radiation protection (ICNIRP) limit is complied. Moreover, the
development of public NIR exposure policy can be initiated to the Malaysia government for
health concern. For future study, the investigation of the suitable material used as antenna
and casing or exposure reduction tool can be done to reduce NIR exposure rate on human
body.
The Nipah virus was first discovered in 1999, following a severe outbreak of viral encephalitis among pig farm workers in Malaysia. The virus was thought to have spread from Pteropus bats to pigs, then from infected pigs to humans by close contact. Mortality of the disease was high at about 40%. The main necropsy finding was disseminated microinfarction associated with vasculitis and direct neuronal involvement. Relapsed encephalitis was seen in approximately 10% of those who survived the initial illness. Since its first recorded emergence in peninsular Malaysia, 10 outbreaks of Nipah virus encephalitis have been reported in Bangladesh and West Bengal in India. The outbreaks occurred from January to May, with Pteropus giganteus as the reservoir of the virus. In Bangladesh, evidence indicated that the virus transmitted directly from bats to human, with human to human transmission as an important mode of spread. The mortality of the illness was higher in Bangladesh which stood at around 70%. This was likely to be due to genetic variation of the virus.