715 research outputs found

    Generation-recombination measurements in silicon M.O.S. capacitors

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    This thesis is concerned with the change in charge on a silicon MOS capacitor (MOS-C) subjected to a voltage step. The transient charge (Q-t) is controlled by the generation and recombination processes in the silicon. A review of these processes in the MOS-C, and of Q-t and other methods of measuring generation lifetime (T(_g)) is given. A thorough experimental investigation of Q-t transients is given including the effects of the guard ring voltage, applied bias, voltage step magnitude, and voltage step polarity. The measurements were performed with an automated apparatus, using a micro computer controlled measuring system developed for the purpose. An improved theory for the Q-t transient has been developed for determining the lifetime. This is midway between the simple theory of Hofstein and the more elaborate computer method of Collins and Churchill. Both the generation and recombination cases of the Q-t transient are covered for the first time and the theoretical results compare well with the experiments. The present Q-t method of determining lifetime is also compared to other Q-t analyses and with the C-t, C-V, and fast ramp methods. Good agreement is obtained with other Q-t and C-t methods, but not with the C-V and fast ramp methods. More than one hundred samples were used in this work but detailed results are presented for typical ones only. This investigation gives confidence in the use of the Q-t method for measuring the minority carrier lifetime easily and accurately

    Corporate governance in Malaysian tourism small and medium-sized enterprises: review of research issues

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    Background: Tourism small and medium-sized enterprises (SMEs) currently emerge as one of the world’s major enterprises with significant changes in its structure and operation. As for Malaysia, the continuous efforts to stimulate the tourism industry by the Malaysian government have created a positive effect on the business activities of SMEs.However, many studies emphasize the problems in managing SMEs in terms of corporate governance for instance lack of awareness on corporate governance structure, lack of awareness on corporate governance operation, size of the board, lack of industry expertise and strategic vision. Objective: This paper presents a general review of the research issues regarding the matter as the first step to enhance further research. Results: The review from related articles indicated that there are three major research issues on corporate governance in SMEs which can also be discussed in the tourism industry.These issues were identified as the roles of corporate governance, the challenges of corporate governance and the significance of corporate governance to SMEs. Conclusion: These three issues should be given serious attention by scholars in determining specific area to be investigated within the context of tourism SMEs.Further, the issues also contribute in terms of practicing corporate governance toward managing tourism SMEs effectively

    Implementation of Frequency Drift for Identification of Solar Radio Burst Type II

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    Sun is constantly produced mass and radiation during its natural activities, which will interact with ionosphere and affect the earth weather. In radio astronomer community, CALLISTO is used to capture the radio signal comes from solar activities such as solar burst. Solar flares and Coronal Mass Ejections (CMEs) were closely associated with the production of solar radio burst Type II and III. However, the determination of solar burst existence is done manually using spectrograph which appears for every 15 minutes.  In order to assist the solar radio researcher to speed up the process of solar burst identification and detection, this work presents a new algorithm to auto classify solar radio burst Type II and III. The value of frequency drift was used as the main idea in this auto classify algorithm because it can easily implemented using MATLAB. There are three main steps involved named as pre-processing, identification and classification. Auto calculation of frequency drift burst on spectra was obtained from two parts which are frequency axis (df) and time axis (dt). The results of the frequency drift implementation in classification algorithm show that the algorithm developed gave almost similar determination as in manual detection. However, there are always have rooms for improvement for better detection system in future which may include specific characterization of bursts and improved noise elimination

    Radio Environment Analysis at Balai Cerap KUSZA for Solar Burst Study

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    Solar radio burst study is one of the new researches done in radio astronomy field in Malaysia. Solar radio burst is associated with Coronal Mass Ejections (CMEs). It occurs when magnetic storm collides with Earth’s magnetosphere. In this paper, we present the level of radio frequency interference (RFI) at selected sites in Malaysia; ESERI (ECE), Balai Cerap KUSZA (BCK), Sungai Chantek (SGC) and Hentian Serdang (HSRDG) focusing on wideband (30kHz-1000 MHz. The threshold for all selected sites is -76.3741 dBm (7.3887), -74.4022 dBm (9.8143), -73.736 dBm (9.4494) and -66.4082 dBm (13.4290) respectively. This study was done to survey the status of frequency allocation in Malaysia for radio astronomy study. In this frequency ranges, radio astronomical sources found are pulsar, deuterium line (DI) and solar radio burst. These radio astronomical sources can be studied best at BCK compared to other sites. This is important to radio astronomer in Malaysia especially in solar burst detection to identify the best site for observation. This study also may provide RFI database to radio astronomers to refer to before conducting an observation

    Determination of Radio Environmental Level in Hydrogen (HI) Band Spectrum by using Kurtosis Analysis

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    The Radio Frequency Interference (RFI) nowadays becomes the serious problem and crucial issue in the radio astronomy observation. It absolutely interferes the radio astronomical lines observation in such influencing the data in radio image become worse and take part reduces the signal power level strength. In this study, the analysis has been done to investigate the radio environment level in a wide band (0-9000 MHz) and hydrogen (HI) band (1300-1500MHz) especially. The observation time is 4 hours in one-minute interval at selected sites namely KUSZA Observatory (KO), Langkawi National Observatory (LNO) and East Coast Environmental Research Institute (ESERI). The radio environment level was measured using spectrum analyser at each site.  In analysis part, the kurtosis method is applied and the highest average of kurtosis values indicates the lowest of radio environment level at these sites. From obtained result, the highest average of kurtosis value in wideband obtained at ‘LNO’ which 20.33. While, the highest in average of kurtosis value in specific band was found at ‘KO’ with value of 6.06.  After further analysis and included with kurtosis value, we conclude the best site of low radio environment level in HI band spectrum was found at ‘KO’ and wide band at ‘LNO’. This preliminary study is important to identify the radio environment level in radio astronomical specific band such as HI band

    Radio frequency interference on nearby radio astronomical lines: relationship between wind speed and radio signal strength measured at East Coast of Peninsular Malaysia

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    The East coast of Peninsular Malaysia receives a strong wind speed, heavy rain and high humidity during the Northeast monsoon. The Malaysian Meteorological Department claims that the wind speed during the Northeast season could reach 55.56 km/h or more. This strong wind speed and heavy rain could contribute to the attenuation of radio signals. This paper investigated the relationship between wind speed (km/h) and radio signal strength, RSS (dBm). The statistical correlation was employed to identify the correlation value and strength between them. The wind speed and RSS were collected during wet and dry seasons at Kusza Observatory, while the Spectrum analyser was used for measuring RSS (dBm) and the weather station for wind speed (km/h). The result showed that the wet season has strong and significant correlation compared to the dry season. Frequencies of 382.5 MHz, 945 MHz and 2160 MHz with correlation values of r = -0.583;-0.631 and -0:514, respectively, showed strong, negative and significant correlations with wind speed in the wet season. As for the dry season, only a frequency of 382.5 MHz showed a strong, positive and significant correlation with r = 0.555, while small and medium for others. This finding is useful to a radio astronomer to help determine the best period for radio astronomy observation with the lowest interference considering the weather in the East Coast of Peninsular Malaysia. Besides, this finding benefits a spectrum of users involved in mobile telecommunication, wireless internet, radio TV transmission and satellite broadcasting

    Breeding of high yielding and dwarf oil palm planting materials using Deli dura × Nigerian pisifera population

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    In practice, progeny and individual palm selection are believed to be the most suitable breeding approach for improvement of quantitative traits in oil palm because their phenotypic expressions are strongly influenced by abiotic factors. Therefore progeny selection approach was applied in this study for the selection of high fresh fruit bunch (FFB) and dwarf oil palm planting materials. Cross between Deli dura and Nigerian pisifera resulted into 34 D × P full sib progenies with 1036 seedlings. For six consecutive years, data were collected on yield and yield component traits, while vegetative traits were recorded once. Bi-parental analysis was carried out using analysis of variance, followed by progenies mean comparison, variance components, heritabilities and cluster analysis. Highly significant (P ≤ 0.01) progeny effect was recorded in this study and this had a pronounced effect on the expression of all the quantitative traits. Progenies performance of FFB varied significantly and it ranged from 166.49 to 220.06 kg/palm/year (kg/p/yr) with trial mean of 192.93 kg/p/yr. Palm height after 8 years of field planting ranged from 1.67 to 2.78 m (control cross) with trial mean of 2.12 m. Broad sense heritability (h2B) was found to be very low (<17.60%) for all the yield traits, however this parameter was high for vegetative traits with palm height having h2B of 90%. Cluster analysis based on all the quantitative traits grouped all the 34 DP progenies into nine distinct clusters. From this study, five progenies (DP3, DP4, DP5, DP8 and DP24) were identified to be high yielding and dwarf palms compare to trial mean. At density of 140 palm/ha, they will produce FFB of 28.63–30.81 t/ha and average of 29.69 t/ha which is about 27.15% higher in FFB when compared to the current planting material with FFB of 23.35 t/ha. In addition, the selected progenies possessed average annual palm increment of 29.82 cm/yr with range of 26 and 32.5 cm/yr which was 57.33% shorter than the current planting material with palm height increment of 45–75 cm/yr

    Genetic variability analysis and selection of pisifera palms for commercial production of high yielding and dwarf oil palm planting materials

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    This study was carried out to evaluate the performance of pisifera (male parent) palms, their general combining ability, and to identify suitable pisifera palms for large scale production of oil palm planting materials. Twenty-four (24) Deli dura palms were nested into 10 Nigerian pisifera male parent palms to produce 1056 tenera (D × P) palms. Tenera palms were planted in two replicates with 16 palms/progeny/replicate. Data collection on yield and yield component traits carried out consecutively for six years. Analysis of variance (ANOVA) followed by the mean comparison and general combining ability were carried out. These were done to know the performance of each of the pisifera parent palms. Additionally, multivariate analysis in form of cluster analysis was done using the quantitative traits. ANOVA showed significant variability among the pisifera palms based on the traits. Fresh fruit bunch (FFB) of each pisifera palm ranged from 173.80 to 211.46 kg/palm/year (kg/p/yr) with a trial mean of 191.92 kg/p/yr, while the oil yield (OY) ranged from 60.24 to 44.06 kg/p/yr with a trial mean of 53.72 kg/p/yr. Based on their mean comparison and the general combining ability, four palms (P01, P03, P09 and P06) have been ranked to be high yielding and good general combiner for FFB and oil yield. While palm P04, P06 and P09 were found to be good combiners for palm height. From these result, four pisifera palms (P01, P03, P09 and P06) have been identified to be high yielding (in terms of FFB and OY), dwarf height and suitable as pollen sources for commercial production of D × P planting materials

    Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

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    Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð¥with constraintsð ð 𥠥 ðandð´ð¥ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis
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