This paper investigated the throughput performance of a secondary user (SU) for a random primary user (PU) activity in a realistic experimental model. This paper proposed a sensing and frame duration of the SU to maximize the SU throughput under the collision probability constraint. The throughput of the SU and the probability of collisions depend on the pattern of PU activities. The pattern of PU activity was obtained and modelled from the experimental data that measure the wireless local area network (WLAN) environment. The WLAN signal has detected the transmission opportunity length (TOL) which was analyzed and clustered into large and small durations in the CTOL model. The performance of the SU is then analyzed and compared with static and dynamic PU models. The results showed that the SU throughput in the CTOL model was higher than the static and dynamic models by almost 45% and 12.2% respectively. Furthermore, the probability of collisions in the network and the SU throughput were influenced by the value of the minimum contention window and the maximum back-off stage. The simulation results revealed that the higher contention window had worsened the SU throughput even though the channel has a higher number of TOLs.
Logging activity is one of the most important activities for tropical countries
including Malaysia, as it produces quality trees for papers. One of the important tree
species is the Acacia Mangium which it produces a soft tree for papermaking enterprises.
The papers are exported to Europe and countries which have high demand for paper
due to the rapid development of the printing industry. Thus we analyzed the height for
individual trees. We investigate the maximum height of the trees from 1990 to 2006
and we fit the data using extreme value model. Some of the data are missing and three
imputation methods we used to solve this problem.
Various claims have been made about the extinction of Malay Reservation Land in the country. Before
independence, the land depreciation was due to the acquisition of land by the British colonial
government for mining, opening of new villages during the communist threat and the mortgage and
sale activities by the Malay landowners to non-Malays. After independence, land depreciation linked
with the acquisition of land by the government through the Land Acquisition Act, 1960. This study is a
content analysis study involving material derived from the secondary source text and earlier research
findings. Emphasis is given to analyze the statistical size of Malay Reservation Land in the country.
Results show that the allegations regarding the depreciation trend of the Malay Reservation Land is
inaccurate and misleading. While the analysis of the size of the Malay Reservation Land found that the
actual percentage of Malay Reservation Land in 2009 was 30.13 percent instead of 11.83 percent as
claimed. The percentage grew steadily in 2013 to 31.85 percent. The analysis also found that there was
confusion about the actual size of Malay Reservation Land in the country.
This study aims at exploring the impact of corruption control on energy efficiency in 60 countries categorized by income: lower middle (LMI), upper middle (UMI), and high (HI). Panel methodology was utilized taking the period of 2000-2017. As cross-sectional dependence is confirmed among the tested equations, the Pesaran (J Appl Econ 22(2):265-312, 2007) unit root test and the augmented mean group estimator proposed by Eberhardt and Teal (2010) were utilized to overcome this matter. The results in general indicate that the lower the corruption is, the more the energy efficiency for all income group economies. Moreover, renewable energy reduces energy efficiency in lower-middle income and high-income economies while its effect is positive in middle-income economies. In addition, the environmental Kuznets curve (EKC) found to be present in all income group economies. Lastly, causality relationships among energy efficiency, corruption, and GDP were present mostly in upper-middle income and high-income economies. From the results, it was recommended that the countries from all income groups should increase their corruption control for the purpose of enhancing energy efficiency.
This study explores whether differences in levels of psychological well-being exist between the Orang Asli in Pertak and those in Gerachi Jaya. Field studies were conductecl on orang Asli in both these villages by using structured interviews. Psychological well-being questionnaires were modified by the researcher based on the Psychological Well-being Scale (Ryff 1989). Psychological well-being was measured in terms of autonomy, control environment, personal development and positive relationships. This study involved 40 Orang Asli from Gerachi City and 35 Orang Asli from Pertak. Data were analyzed with SPSS software using t-tests. Results show that the levels of psychological well-being between the two groups were not significantly different (t= 0.339, k> 0.05). Implications are also discussed.
The changes on the vegetables oil trading environment might change the foundation of palm oil pricing and induce a structural change to the price model. Failing to take it account the structural change in a data series might lead to misspecification of the actual model. This study, however, showed that structural change was not present in the monthly, January 1983 to July 1995, palm oil price, but it was present on the unconditional variance. The underlying model of this series was ARIMA (3, 1, 0) with ARCH (1). The critical change of the unconditional variance took place in April 1989.
Perubahan dalam suasana perdagangan minyak sayuran boleh mengubah asas harga minyak kelapa sawit. Seterusnya ia merangsang perubahan dalam struktur model harga minyak tersebut. Kegagalan untuk mengambil kira perubahan struktur dalam siri data menjadikan model itu tidak menepati spesifikasi daripada model sebenar. Kajian ini mendapati bahawa perubahan struktur tidak berlaku bagi data harga minyak sawit dari Januari 1983 hingga Julai 1995. Tetapi perubahan berlaku pada varians tidak bersyaratnya. Model asas bagi siri ini adalah ARIMA (3,1,0) dengan ARCH(1). Didapati juga bahawa perubahan yang kritikal bagi varians tidak bersyarat berlaku pada bulan April 1989.
The study of cohesive sediment in the laboratory gives rise to a number of instrumentation problems, especially in the location of mud bed, fluid mud and hindered settling layers and in the measurement of flow velocities. This paper describes the application of medical diagnostic ultrasound technique in the cohesive sediment study conducted at the University of Liverpool, United Kingdom. This paper illustrates that the use of ultrasound technique creates a reasonably flexible environment for the study of fluid mud phenomenon in which bed formation and flow velocities can be measured easily, accurately and non-intrusively. This in turn will assist in development of computer models to predict the environmental impact, siltation rates and dredging requirements in both new and existing ports and harbour developments.
Kajian endapan berjeleket di dalam makmal mengalami pelbagai masalah peralatan, terutamanya bagi menentukan lokasi dasar lumpur, pengenapan terhalang dan pengukuran halaju aliran. Dalam makalah ini diterangkan penggunaan teknologi diagnosis perubatan ultrabunyi dalam kajian endapan berjeleket, yang dijalankan di University of Liverpool, United Kingdom. Ditunjukkan bahawa penggunaan teknologi ultrabunyi keadaan yang begitu boleh suai bagi kajian fenomenon lumpur yang pembentukan dasar dan halaju aliran dapat diukur dengan mudah, tepat dan tanpa gangguan. lni seterusnya dapat membantu di dalam pembangunan model komputer bagi menjangka kesan sekitaran, kadar enapan dan keperluan mengorek bagi pembangunan kawasan pelabuhan baru dan sedia ada.
A distinct element approach has been introduced for simulating the plugging performance of granular lost circulation materials (LCM) in a fracture. This approach solves the fully coupled fracture walls, fluid and particles system in an interactive environment. The effects of the particle shape, size distribution and concentration on the fracture-plugging performance of the granular LCM have been investigated using the three-dimensional particle flow code (PFC3D). The simulated results showed that the irregular granular LCM could plug a fracture width larger than the sieving granulation by single-particle bridging type. The particle size distribution (PSD) of LCM dominates the plugging depth and efficiency in a fracture and there exists an optimum concentration for maximum effect of LCM additives.
After twenty-four years of government efforts, the latest national recycling rate in Malaysia rose from 5% in 1993 to approximately 24.6% in 2017. However, the practice of solid waste recycling in developing countries is still challenging compared to developing countries. Especially in Malaysia, a multi-ethnic country where people with different ethics have different living lifestyles. Still, Malaysia faces rapidly increasing solid waste and management costs, lacks appropriate data on solid waste management and recycling, lacks awareness of the 3R's (reduce, reuse and recycle) culture and lacks policies to promote 3R's culture. In addition, prior to the enforcement of ACT 672, information and networks between stakeholders have been limited for more than 20 years. Some scholars believe that the success of recycling practices is mainly influenced by community recycling behaviours. Therefore, in order to improve and evaluate the effectiveness of current national solid waste recycling management systems, research and assessment of community recycling behaviours are essential. This paper aims to evaluate the factors that attract communities to implement recycling in their daily lives and to obtain data through quantitative survey methods. Face-to-face questionnaires are conducted through purposive sampling and collected data is further analysed by PASW statistical tools. The comparison between recyclers and non-recyclers are presented in terms of frequency, means scores and radar chart. The results indicate that policy makers involved in the planning, organisation, and implementation of community recycling programs have to focus on strategies that engage community members and adopt recycling practices to improve environmental impact by changing their attitudes. Based on the results of means scores, the type of age, occupation and place of life must be taken into consideration in order to organize future recycling campaigns or awareness programs. In conclusion, the information will help policymakers make better solid waste recycling management to meet the needs of the public.
Miocene larger benthic foraminifera have been discovered from a limestone unit of the Kalumpang Formation. The limestone is exposed at the Teck Guan Quarry, Tawau, southeast Sabah. The Kalumpang Formation consists predominantly of interbedded mudstone and sandstone (graywacke), conglomerate, limestone, marl, chert and volcanic rocks. Five limestone samples have been collected and processed for petrographic analysis and identification of larger benthic foraminifera. The limestone is classified as packstone and mudstone. A total of seventeen species of larger benthic foraminifera have been identified. The foraminifera are divided into two assemblages namely Assemblage I and Assemblage II. Assemblage I is characterized by the presence of Lepidocyclina (Nephrolepidina) parva, Operculina sp. and Lepidocyclina (Eulepidina) formosa. This assemblage is an indicative of Aquitanian to Burdigalian in age (Early Miocene). Assembalge II comprises of Lepidocyclina (Nephrolepidina) sumatrensis, Lepidocyclina (Nephrolepidina) angulosa, Lepidocyclina (Nephrolepidina) ferreroi Lepidocyclina sp., Miogypsina sp., Katacycloclypeus annulatus, Katacyloclypeus martini, Cycloclypeus carpenteri, Cycloclypeus indopacificus, Cycloclypeus sp., Flosculinella bontangensis, Operculina complanata, Amphistegina bowdenensis and Amphistegina sp. This assemblage is an indicative of Langhian to Serravallian age (Middle Miocene). The foraminiferal assemblages suggest that the depositional environment was a warm tropical shallow-marine at the fore-reef shelf zone.
Dengue fever is a vector-borne viral disease which is now endemic in more than 100 countries affecting more than 2.5 billion people worldwide. In recent years, dengue fever has become a major threat to public health in Pakistan. In this paper, we derived an explicit formula for reproduction number R0 (the most important epidemiological parameter) and then used real data of dengue fever cases of different hospitals of Lahore (Pakistan) on R0. Conditions for local stability of equilibrium points are discussed. In the end, simulations are carried out for different situations.
In most research including environmental research, missing recorded data often exists and has become a common problem for data quality. In this study, several imputation methods that have been designed based on the techniques for functional data analysis are introduced and the capability of the methods for estimating missing values is investigated. Single imputation methods and iterative imputation methods are conducted by means of curve estimation using regression and roughness penalty smoothing approaches. The performance of the methods is compared using a reference data set, the real PM10 data from an air quality monitoring station namely the Petaling Jaya station located at the western part of Peninsular Malaysia. A hundred of the missing data sets that have been generated from a reference data set with six different patterns of missing values are used to investigate the performance of the considered methods. The patterns are simulated according to three percentages (5, 10 and 15) of missing values with respect to two different sizes (3 and 7) of maximum gap lengths (consecutive missing points). By means of the mean absolute error, the index of agreement and the coefficient of determination as the performance indicators, the results have showed that the iterative imputation method using the roughness penalty approach is more flexible and superior to other methods.
This paper investigates the compressibility characteristics of compacted clay treated with cement, peat ash and silica
sand. For this purpose, one dimensional consolidation tests were conducted to determine the soil consolidation properties.
The test specimens were trimmed from the compaction test specimen. The 1D consolidation test specimen was subjected
to the normal pressures of 2.5, 5, 10, 20, 40, 80 and 160 kPa in sequence on the test specimen which was saturated with
distilled water. At the end of the loading period of 80 kPa, the vertical load was removed and the specimen was allowed
to expand for 24 h for the purpose of evaluating of its swelling behavior. The results showed that void ratio of the soil
specimens decreased with increasing effective normal pressure. The laboratory investigation clearly demonstrates that,
settlement is as the compression of a soil specimen due to vertical loading applied at the top surface of the 1D consolidation
test specimen. It was concluded that, the compression settlement of the stabilized soil with the binder composition of
18% cement, 2% peat ash and 5% silica sand improved by almost 1.3-fold. A notable discovery is the suitability of the
stabilized soil for road embankment and low lying marginal area for foundation works; also solving the environmental
problems in relation to peaty ground. However, sufficient laboratory and field testing are required.
Prevention and mitigation of rainfall induced geological hazards after the Ms=8 Wenchuan earthquake on May 12th, 2008 were significant for rebuild of earthquake hit regions. After the Wenchuan earthquake, there were tens of thousands of fractured slopes which were broken and loosened by the ground shaking, they were very susceptible to heavy rainfall and change forms into potential debris flows. In order to carry out this disaster reduction and prediction effectively in Longmenshan region, careful real-time monitoring and pre-warning of mountain hazards in both regional and site-specific scales is reasonable as alternatives in Wenchuan earthquake regions. For pre-warning the failure of fractured slopes induced by rainfall, the threshold value or the critical value of the precipitation of hazards should be proposed. However, the identification of critical criterion and parameters to pre-warning is the most difficult issue in mountainous hazards monitoring and pre-warning system especially in the elusive and massive fractured slopes widespread in Wenchuan earthquake regions. In this study, a natural coseismic fractured landslide in the Taziping village, Hongkou County, Dujianyan City, was selected to conduct the field experimental test, in order to identify the threshold parameters and critical criterion of the fractured slopes of Taziping. After the field experimental test, the correlation of rainfall intensity, rainfall duration and accumulative rainfall was investigated. The field experimental test was capable of identifying the threshold factors for failure of rainfall-induced fractured slopes after the giant earthquake.
The seasonal variation of spider assemblages in botanical garden was investigated. The spiders were manually collected by diurnal and nocturnal session between two seasons. A total of 19 families from 65 genera and 96 species were recorded. Richness-estimator indicates the inventory were 67% complete within the botanical garden. The capture rate for web-weavers were higher compared with non-web weavers. The comparison value showed the species composition and abundance were similar between seasons. Spider abundance was not affected between wet and dry season in tropical countries.
The growth of residential and commercial areas threatens vegetation and ecosystems. Thus, an urgent urban management
issue involves determining the state and the quantity of urban tree species to protect the environment, as well as controlling
their growth and decline. This study focused on the detection of urban tree species by considering three types of tree
species, namely, Mesua ferrea L., Samanea saman, and Casuarina sumatrana. New rule sets were developed to detect these
three species. In this regard, two pixel-based classification methods were applied and compared; namely, the method of
maximum likelihood classification and support vector machines. These methods were then compared with object-based
image analysis (OBIA) classification. OBIA was used to develop rule sets by extracting spatial, spectral, textural and color
attributes, among others. Finally, the new rule sets were implemented into WorldView-2 imagery. The results indicated
that the OBIA based on the rule sets displayed a significant potential to detect different tree species with high accuracy.
Litter decomposition is vital for carbon and nutrient turnover in terrestrial ecosystems, and this process has now
been thoroughly demonstrated to be regulated by various mechanisms. The total environment has been continuously
changing in recent decades, especially in high-latitude regions; these alterations, however, profoundly contribute to the
decomposition process, but a comprehensive recognition has not available. Here we reviewed the empirical observations
and current knowledge regarding how hydrological leaching and freeze-thaw events modulate early decomposition of
plant litter. Leaching contributes a considerable percentage of mass loss and carbon and nutrient release in early stage of
decomposition, but the magnitudes are different between species levels depending on the chemical traits. Frequent freezing
and thawing events could positively influence decomposition rate in cold biomes but also hamper soil decomposer and
there is no general and predictable pattern has been emerged. Further experiments should be manipulated to estimate
how the altered freezing and thawing effect on carbon and nutrient release from plant litter to better understanding the
changing environment on litter decomposition.
A single sample from the logged section at eastern side of Gua Panjang limestone hill, southwest of Kampung Kubang
Rasa Village, Merapoh, has yielded 5 very important conodont species. They are Hindeodus parvus erectus, Hindeodus
parvus parvus, Hindeodus latidentatus latidentatus, Hindeodus latidentatus praeparvus, Hindeodus postparvus, Hindeodus
eurypge and Isarcicella staeschi. These Early Triassic conodonts were obtained in a bioclastic dolostone sample, located
2.5 m above bioclastic grainstone which yielded Late Permian foraminifera. The conodonts found were given Conodont
Alteration Index (CAI) scale of 5, consistent with the heating of Main Range granitoid during Indosinian Orogeny.
Limestone harbouring basal Triassic conodonts in Gua Panjang is interpreted to be deposited in an open shallow marine
shelf environment.
This paper examines the effects of energy consumption, economic growth, and financial development on carbon emissions in a panel of 122 countries. We employ both first-generation and second-generation cointegration and estimation procedures in order to address diverse economic and econometric issues such as heterogeneity, endogeneity, and cross-sectional dependence. We find a cointegration relationship between the variables. Energy consumption, economic growth, and financial development have detrimental effects on carbon emissions in the full sample. When the sample is split into different income groups, we reveal that economic growth and financial development mitigate carbon emissions in high-income group but have the opposite effects in low-income and middle-income groups. The implication of the findings is that energy consumption increases carbon emissions. While high levels of income and financial development decrease carbon emissions, low levels of income and financial development intensify it. Based on the findings, the paper makes some policy recommendations.
The combined effort of the neuroscience and psychology cluster at the Universiti Sains Malaysia (USM)-fundamental, applied and clinical-has moved the institution to the number two position in the country, behind Universiti Malaya. The strategy to join the Global Brain Consortium (GBC) and put Malaysia on the map to address the GBC mission, vision, focus areas and outcomes began recently, in May 2019.