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Markov Chain Modelling of Reliability Analysis and Prediction under Mixed Mode Loading

Chinese Journal of Mechanical Engineering 2015年第2期28卷 307-314页

作者： SINGH Salvinder abdullah Shahrum nik mohamed nik abdullah MOHD NOORANI Mohd Salmi Department of Mechanical and Materials Engineering Faculty of Engineering & Built EnvironmentUniversiti Kebangsaan Malaysia Department of Mechanical Engineering Universiti Malaysia Pahang School of Mathematical Sciences Faculty of Science and TechnologyUniversiti Kebangsaan Malaysia

The reliability assessment for an automobile crankshaft provides an important understanding in dealing with the design life of the component in order to eliminate or reduce the likelihood of failure and safety *** failures of the crankshafts are considered as a catastrophic failure that leads towards a severe failure of the engine block and its other connecting *** reliability of an automotive crankshaft under mixed mode loading using the Markov Chain Model is *** Markov Chain is modelled by using a two-state condition to represent the bending and torsion loads that would occur on the *** automotive crankshaft represents a good case study of a component under mixed mode loading due to the rotating bending and torsion *** estimation of the Weibull shape parameter is used to obtain the probability density function,cumulative distribution function,hazard and reliability rate functions,the bathtub curve and the mean time to *** various properties of the shape parameter is used to model the failure characteristic through the bathtub curve is ***,an understanding of the patterns posed by the hazard rate onto the component can be used to improve the design and increase the life cycle based on the reliability and dependability of the *** proposed reliability assessment provides an accurate,efficient,fast and cost effective reliability analysis in contrast to costly and lengthy experimental techniques.

关键词： reliability Weibull Markov Chain mixed mode failure

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A floating point conversion algorithm for mixed precision computations

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Journal of Zhejiang University-Science C(Computers and Electronics) 2012年第9期13卷 711-718页

作者： Choon Lih HOO Sallehuddin mohamed HARIS nik abdullah nik mohamed Department of Mechanical and Materials Engineering Universiti Kebangsaan MalaysiaUKM Bangi 43600Malaysia

The floating point number is the most commonly used real number representation for digital computations due to its high precision characteristics. It is used on computers and on single chip applications such as DSP chips. Double precision (64-bit) representations allow for a wider range of real numbers to be denoted. However, single precision (32-bit) operations are more efficient. Recently, there has been an increasing interest in mixed precision computations which take advantage of single precision efficiency on 64-bit numbers. This calls for the ability to interchange between the two formats. In this paper, an algorithm that converts floating point numbers from 64- to 32-bit representations is presented. The algorithm was implemented as a Verilog code and tested on field programmable gate array (FPGA) using the Quartus II DE2 board and Agilent 16821A portable logic analyzer. Results indicate that the algorithm can perform the conversion reliably and accurately within a constant execution time of 25 ns with a 20 MHz clock frequency regardless of the number being converted.

关键词： Double precision Single precision FPGA Verilog HooHar algorithm

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On-line CO,CO_2 emissions evaluation and(benzene, toluene, xylene) determination from experimental burn of tropical biomass

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Journal of Environmental Sciences 2015年第7期27卷 239-244页

作者： Mohammed F.Tawfiq mohamed Kheireddine Aroua nik Meriam nik Sulaiman Chemical Engineering Department Faculty of Engineering University of Malaya

Atmospheric pollution and global warming issues are increasingly becoming major environmental concerns. Fire is one of the significant sources of pollutant gases released into the atmosphere; and tropical biomass fires, which are of particular interest in this study,contribute greatly to the global budget of CO and CO2. This pioneer research simulates the natural biomass burning strategy in Malaysia using an experimental burning facility. The investigation was conducted on the emissions（CO2, CO, and Benzene, Toluene, Ethylbenzene,Xylenes（BTEX）） from ten tropical biomass species. The selected species represent the major tropical forests that are frequently subjected to dry forest fire incidents. An experimental burning facility equipped with an on-line gas analyzer was employed to determine the burning emissions. The major emission factors were found to vary among the species, and the specific results were as follows. The moisture content of a particular biomass greatly influenced its emission pattern. The smoke analysis results revealed the existence of BTEX,which were sampled from a combustion chamber by enrichment traps aided with a universal gas sampler. The BTEX were determined by organic solvent extraction followed by GC/MS quantification, the results of which suggested that the biomass burning emission factor contributed significant amounts of benzene, toluene, and m,p-xylene. The modified combustion efficiency（MCE） changed in response to changes in the sample moisture ***, this study concluded that the emission of some pollutants mainly depends on the burning phase and sample moisture content of the biomass.

关键词： Emission Biomass Experimental BTEX CO CO2 GG/MS

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Numerical and experimental investigation of three-dimensionality in the dam-break flow against a vertical wall

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Journal of Hydrodynamics 2018年第4期30卷 682-693页

作者： mohamed M.Kamra nik Mohd Cheng Liu Makoto Sueyoshi Changhong Hu Interdisciplinary Graduate School of Engineering Seieneesl Kyushu University Kasuga Fukuoka Japan Research Institute for Applied Mechanics Kyushu University Kasuga Fukuoka Japan

The three-dimensionality extent of the dam break flow over a vertical wall is investigated numerically and experimentally in this paper. The numerical method is based on Reynolds averaged Navier-Stokes（RANS） equation that describes the three-dimensional incompressible turbulent flow. The free surface is captured by using the unstructured multi-dimensional interface capturing（UMTHINC） scheme. The equations are discretized on 2-D and 3-D unstructured grids using finite volume method. The numerical simulations are compared with newly conducted experiment with emphasis on the effect of three-dimensionality on both free surface and impact pressure. The comparison between the numerical and experimental results shows good agreement. Furthermore, the results also show that 3-D motion of the flow originates at the moment of impact at the lower corners of the impact wall and propagates to the inner region as time advances. The origin of the three-dimensionality is found to be the turbulence development as well as the relative velocity between the side wall region and the inner region of the wave front at the moment of impact.

关键词： Water impact dam break flow UMTHINC scheme three-dimensionality

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Bee pollen extract of Malaysian stingless bee enhances the effect of cisplatin on breast cancer cell lines

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Asian Pacific Journal of Tropical Biomedicine 2016年第3期6卷 265-269页

作者： Wan Adnan Wan Omar Nur Asna Azhar Nurdianah Harif Fadzilah nik Nur Syazni nik mohamed Kamal Advanced Medical and Dental Institute Universiti Sains Malaysia

Objective: To evaluate the antioxidant and antiproliferative effect of methanolic bee pollen extract(BPE) of Malaysian stingless bee [Lepidotrigona terminata(L. terminata)]and its synergistic effect with cisplatin(a chemotherapeutic drug) on MCF-7 cancer cell ***: The antioxidant activity of BPE from L. terminata was measured by using1,1-diphenyl-2-picrylhydrazyl radical(DPPH) assay. Antiproliferative activity at different concentrations of BPE and cisplatin was determined through using MTT assay on MCF-7 and L929 cell lines. An interaction effect(synergistic, additive and antagonistic) between BPE and cisplatin was determined by Compu Syn software based on MTT assay ***: The EC50(50% decrement of DPPH inhibition) of BPE was 0.5 mg/m L.L. terminata BPE exhibited antiproliferative activity on both cancer and normal cell *** IC50(concentration of drug that was required for 50% of cell inhibition in vitro) of BPE on MCF-7 was 15 mg/m L whereas in normal cell line L929 was 26 mg/m L. The IC50 for cisplatin on MCF-7 was 20 mmol/L. The combination effect of BPE and cisplatin on MCF-7 cells showed that BPE at 15 mg/m L was able to potentiate the inhibitory effect of cisplatin at all different concentrations(2.5–20.0 mg/m L). The average of cancer cells inhibition which was potentiated by BPE was around 50%. A combination index values of less than 1 reported in the Compu Syn software further proved the synergistic effect between BPE and cisplatin, suggesting that BPE was working synergistically with ***: Our study therefore suggested that BPE of Malaysian stingless bee,L. terminata is a potential chemopreventive agent and can be used as a supplementary treatment for chemotherapy drugs. BPE might be able to be used to potentiate the effect of chemotherapy drugs with the possibility to reduce the required dose of the drugs. The molecular mechanisms of how the BPE exerts antiproliferative activity will be a much interesting area to loo

关键词： Bee pollen extract Antioxidant Antiproliferative activity Synergistic effect Malaysian stingless bee

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Laboratory efficacy of mycoparasitic fungi(Aspergillus tubingensis and Trichoderma harzianum) against tropical bed bugs(Cimex hemipterus)(Hemiptera:Cimicidae)

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Asian Pacific Journal of Tropical Biomedicine 2017年第4期7卷 288-293页

作者： Zulaikha Zahran nik Mohd Izham mohamed Nor Hamady Dieng Tomomitsu Satho Abdul Hafiz Ab Majid Household and Structural Urban Entomology Laboratory Vector Control Research UnitSchool of Biological SciencesUniversiti Sains Malaysia Plant Pathology Laboratory School of Biological SciencesUniversiti Sains Malaysia Institute of Biodiversity and Environmental Conservation Universiti Malaysia Sarawak Department of Microbiology Faculty of Pharmaceutical SciencesFukuoka University

Objective: To test the effectiveness of conidial spore formulations [Aspergillus tubingensis(***) and Trichoderma harzianum(***)] against tropical bed bugs, Cimex ***: Spore formulations were made from two fungal strains, *** and *** bed bugs were exposed to the conidial spores placed soaked onto a fabric cloth for 1 h and the mortality counts were recorded daily until 14 ***: Mean survival times based on Kaplan–Meier survival analysis showed no significant differences between all the concentrations in both the fungal isolates:*** and ***, the evaluation of both the isolates in terms of virulence resulted in low lethal hours in all the concentrations except for the high concentration of ***(LT_(50)= 44.629 h) at the conidial exposure of 1 × 10~6 spores/*** mortality of the bed bugs was observed from Day 6 to Day 12, ranging from 13% to 90% in all three concentrations of *** reference to the *** exposure, the concentration of 1 × 10~4 spores/mL displayed a gradual increase in the percentage mortality of 90 on Day ***: Approaches to the bed bugs treatment should be explored in-depth using a natural biological agent like fungus especially *** to reduce this pest population, in order to replace chemical methods.

关键词： Tropical bed bug Mycoparasitic fungi Aspergillus tubingensis Trichoderma harzianum Bio-control

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Environmental management system and community＇s spillover behavior

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Journal of Environmental Science and Engineering 2009年第9期3卷 58-66页

作者： nik Ramli nik Abd Rashid Kamsol mohamed Kassim Kamaruzaman Jusoff Faculty of Business and Management University Teknologi Mara Arau Perlis 02600 Malaysia Faculty of Forestry University Putra Serdang Selangor 43400 Malaysia

The purpose of this study is to explore how business organizations could effectively promote positive environmental norms among a larger section of the community. This study hypothesized that the development of a feeling of high involvement among employees of organizations implementing the Environmental Management System （EMS） could result in the spillover phenomena of other environmentally responsible behavior in different domains such as, consumer preferences for environment-friendly products. The study also confirms the effects of environmental attitude （EA） and concrete knowledge （CK） as a mediator; acting not only as an axis to the spillover phenomenon but is also found to be the crucial factor in determining the strength of the whole spillover process.

关键词： spillover behavior community environmental attitude concrete knowledge environmental management system

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The Effects of Stacking Sequence on Dynamic Mechanical Properties and Thermal Degradation of Kenaf/Jute Hybrid Composites

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Journal of Renewable Materials 2021年第1期9卷 73-84页

作者： Tabrej Khan mohamed Thariq Hameed Sultan Mohammad Jawaid Syafiqah Nur Azrie Safri Ain Umaira Md Shah Mohd Shukry Abdul Majid nik Noriman Zulkepli Haliza Jaya Department of Aerospace Engineering Faculty of EngineeringUniversiti Putra MalaysiaSerdang43400Malaysia Laboratory of Biocomposite Technology Institute of Tropical Forestry and Forest ProductsUniversiti Putra MalaysiaSerdang43400Malaysia Aerospace Malaysia Innovation Centre Prime Minister’s DepartmentMIGHT Partnership HubCyberjaya63000Malaysia School of Mechatronic Engineering Universiti Malaysia PerlisPauh Putra CampusArau02600Malaysia School of Manufacturing Engineering Universiti Malaysia PerlisPauh Putra CampusArau02600Malaysia Center of Excellence Geopolymer and Green Technology Faculty of Engineering TechnologyUniversiti Malaysia PerlisArau02600Malaysia

This research focused on the dynamic mechanical and thermal properties of woven mat jute/kenaf/jute(J/K/J)and kenaf/jute/kenaf(K/J/K)hybrid *** mechanical analysis(DMA)and Thermo-gravimetric Analysis(TGA)were used to study the effect of layering sequence on the thermal properties of kenaf/jute hybrid *** DMA results;it was found that the differences in the stacking sequence between the kenaf/jute composites do not affect their storage modulus,loss modulus and damping *** the TGA and DMA results,it has been shown that stacking sequence has given positive effect to the kenaf/jute hybrid composite compared to pure epoxy *** is because kenaf and jute fibre has increased the Tg values of the composites,thus affect the thermal *** showed that the storage modulus for kenaf/jute hybrid composites increased compared with pure epoxy composites with increasing temperature and the values of remained almost the same at glass transition temperature(Tg),the hybrid composite perhaps due to the improved fibre/matrix interface *** preliminary analysis could provide a new direction for the creation of a novel hybrid composite which offers unique properties which cannot be accomplished in a single material system.

关键词： Hybrid composites dynamic mechanical thermal analysis(DMTA) thermo-gravimetric analysis

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Application of in-house method for determinationof radium isotopes in environmental samples usingthe Liquid Scintillation counting technique

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Journal of Analytical Sciences, Methods and Instrumentation 2011年第1期1卷 1-8页

作者： nik Azlin nik Ariffin Zal Uyun Wan Mahmood Che Abd Rahim mohamed School of Environmental & Natural Resources Sciences Faculty of Science and Technology Universiti Kebangsaan Malaysia Radiochemistry and Environment Group Malaysia Nuclear Agency Marine Ecosystem Research Centre (EKOMAR) Universiti Kebangsaan Malays

A method for determination of 226Ra and 228Ra in environmental samples using the α-β coincidence liquid scintillation counting (LSC) has been developed. Radium were preconcentrated from environmental samples by coprecipitation with BaSO4, then purified from others radionuclide interferences using the cation column exchange (Bio-Rad AG 50 W-X4 resin with 200-400 mesh size and H+ form) and operating in warm temperature which is between 70-80oC. Then, the Ba(Ra)SO4 precipitate was filtered through the Millipore filter paper, dried and weighed to calculate chemical yield. The activity concentration of radium isotopes in mixture of liquid scintillation cocktails were measured using LSC after being stored for over 21 days to allow the growth of the progeny nuclides. The method has been validated with a certi-fied reference material supplied by the International Atomic Energy Agency and reliable results were obtained. The radiochemical yields for radium were 59% - 90% and recovery was 97% and 80% for 226Ra and 228Ra, respectively. Sixteen seawater and fish flesh samples collected in Kapar coastal water have been analyzed with the developed method. The obtained radium activity concentrations in seawater were in the range of 02.08 ± 0.82 mBq/L to 3.69 ± 1.29 mBq/L for 226Ra and 6.01 ± 3.05 mBq/L to 17.07 ± 6.62 mBq/L for 228Ra. Meanwhile, the activity concentrations of 226Ra and 228Ra in fish flesh were in the range of 11.82 ± 5.23 – 16.53 ± 6.53 Bq/kg dry wt. and 43.52 ± 16.34 – 53.57 ± 19.86 Bq/kg dry wt., respectively.

关键词： 226Ra 228Ra Environmental Samples Chemical Yield Liquid Scintillation Counting

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Diffuse unilateral subacute neuroretinitis in children:Report of three cases

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Journal of Acute Disease 2021年第3期10卷 122-125页

作者： nik Mohd Noor nik-Nurfarhana Ahmad Shahrudin Azima Khonji Ismaeel-mohamed Embong Zunaina Department of Ophthalmology School of Medical SciencesHealth CampusUniversiti Sains Malaysia16150 Kubang KerianKelantanMalaysia Hospital Universiti Sains Malaysia Jalan Raja Perempuan Zainab II16150 Kubang KerianKelantanMalaysia Department of Ophthalmology Salmaniya Medical ComplexP.O.Box 12Ministry of HealthManama CityKingdom of Bahrain

Rationale:Diffuse unilateral subacute neuroretinitis is a form of posterior uveitis and has a few clinical presentations according to the onset of ***’concern:A girl(5-year-old)and 2 boys(both 12-year-old)were included in this *** presentation,the visual acuity ranges from 6/12 to 6/*** three cases had different symptoms(case 1:floaters;case 2:eye redness and pain;case 3:central scotoma).All of them had variable posterior uveitis features(case 1:vitritis and focal retinitis;case 2:subretinal larva track;case 3:choroiditis).Diagnosis:Diffuse unilateral subacute ***:All 3 patients were treated with oral ***:All patients showed remarkable resolution of inflammatory reactions of the eye and also improvement of ***:High index of suspicion should be made for children and young adults who are previously healthy but presented with suddenly onset of reduced vision with clinical features of posterior uveitis of variable *** features together with a full blood picture can help to diagnose the problem when other parameters are negative.

关键词： Diffuse unilateral subacute neuroretinitis Worms’infestations Nematodes

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