GLORIA

GEOMAR Library Ocean Research Information Access

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    In: Journal of Advanced Research in Fluid Mechanics and Thermal Sciences, Akademia Baru Publishing, Vol. 99, No. 1 ( 2022-10-17), p. 17-27
    Abstract: The influence of thermal annealing on the surface morphologies and structural characteristics of zinc oxide (ZnO) nanopowders synthesized via the solution immersion method for triboelectric nanogenerator applications is reported in this paper. The ZnO nanopowders were thermally treated at different temperatures of annealing in the ranges between 300°C to 700°C for 1 hour, and their surface morphologies and structural properties were studied using field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) analysis. The ZnO nanopowders have a polycrystalline, hexagonal wurtzite structure and are composed of ZnO nanoparticles and hexagonal nanorods. ZnO based tribolectric nanogenerators were fabricated with these nanopowders and their performance was assessed in terms of the output voltage. It is found that the ZnO based triboelectric nanogenerator fabricated with ZnO nanopowders annealed at 500°C has superior performance compared with the other nanogenerators, with an average output voltage of 1.95 V. This corresponds to a fourfold increase in output voltage relative to that of the ZnO based triboelectric nanogenerator fabricated with as-deposited ZnO nanopowders. In conclusion, thermal annealing significantly influences particle size and crystallinity of ZnO nanopowders, which in turn, influences the output voltage of ZnO based triboelectric nanogenerators.
    Type of Medium: Online Resource
    ISSN: 2289-7879
    URL: Issue
    Language: Unknown
    Publisher: Akademia Baru Publishing
    Publication Date: 2022
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 2
    Online Resource
    Online Resource
    IOP Publishing ; 2021
    In:  IOP Conference Series: Materials Science and Engineering Vol. 1088, No. 1 ( 2021-02-01), p. 012114-
    In: IOP Conference Series: Materials Science and Engineering, IOP Publishing, Vol. 1088, No. 1 ( 2021-02-01), p. 012114-
    Abstract: Generally, dye sensitizers make use of inorganic elements such as ruthenium or osmium. However, these elements were toxic and hard to be produced due to its rarity. Alternatively, organic and natural sensitizer derived from various organic sources were studied. In this research, a natural dye which is chlorophyll b (Chl-b) extracted from Mitragyna Speciosa or ketum leaf pigment is used as the dye sensitizer. The geometry, optical properties and electronic properties were observed by the computational method using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) with B3LYP/6-31G with Gaussian-03 and Gaussview-03 software. Here, properties of bulk Chl-b were firstly obtained from databank as a control experiment. It was to be compared with the properties of Chl-b extracted using water as solvent. It can be observed that, UV-Vis of Chl-b showed peak absorbance at 430 nm at the blue light region of the visible light. The highest occupy molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) were calculated by DFT ground state level. Bandgap of Chl-b without and with water extraction are 2.12 eV and 2.10 eV respectively, while excitation state of LUMO to conduction band are 1.21 eV and 1.27 eV respectively. It shows that the bandgap is lower when extracted using water as the solvent. Therefore, water extracted Chl-b tends to give a better result for HOMO/LUMO energy and voltage open circuit, Voc, HOMO and LUMO energy resulted in higher energy than the bulk Chl-b in Mitragyna leaves. This lower bandgap is attributed to the addition of electrons contents in the extracted molecules which is beneficial for dye-sensitize solar cells, DSSC.
    Type of Medium: Online Resource
    ISSN: 1757-8981 , 1757-899X
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2021
    detail.hit.zdb_id: 2506501-4
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 3
    Online Resource
    Online Resource
    IOP Publishing ; 2020
    In:  Journal of Physics: Conference Series Vol. 1535, No. 1 ( 2020-05-01), p. 012010-
    In: Journal of Physics: Conference Series, IOP Publishing, Vol. 1535, No. 1 ( 2020-05-01), p. 012010-
    Abstract: The effect of thickness of aluminium doped zinc oxide (AZO), doping concentration of Aluminium as well as the annealing temperature to the fabrication of AZO photoconductor sensor is the main focused of this research. Silvaco TCAD tool is used to fabricate the AZO photoconductor sensor and to obtain the electrical characteristics of the device by using its simulation software. The device performance was investigated with various thicknesses of AZO film, annealing temperatures and different Al doping concentration. The Al doping was varied 1×1017 cm −3 , 1×1019 cm −3 and 1×1021 cm −3 , the thickness was varied 0.2 nm, 1.0 nm and 1.2 nm and the temperature was varied from 300°C, 500°C and 700°C. The electrical properties of AZO photodetector were characterized using current voltage (I-V) measurement system respectively. The result shows that by changing the thicknesses of aluminium doped zinc oxide (AZO), and the doping concentration of aluminium in the zinc oxide have greatly improved the electrical characteristics as well as the electrical performances of the photoconductor sensor. Indeed, the post fabrication and simulation process using simulation tools is helpful for the determination of the parameters during the later process of the real device fabrication.
    Type of Medium: Online Resource
    ISSN: 1742-6588 , 1742-6596
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2020
    detail.hit.zdb_id: 2166409-2
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 4
    Online Resource
    Online Resource
    UiTM Press, Universiti Teknologi MARA ; 2022
    In:  Journal of Electrical & Electronic Systems Research Vol. 21, No. OCT2022 ( 2022-11-01), p. 149-155
    In: Journal of Electrical & Electronic Systems Research, UiTM Press, Universiti Teknologi MARA, Vol. 21, No. OCT2022 ( 2022-11-01), p. 149-155
    Type of Medium: Online Resource
    ISSN: 1985-5389
    Language: Unknown
    Publisher: UiTM Press, Universiti Teknologi MARA
    Publication Date: 2022
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 5
    In: Key Engineering Materials, Trans Tech Publications, Ltd., Vol. 946 ( 2023-05-25), p. 87-92
    Abstract: In this project, the surface structure of III-V semiconductor, GaAs, was altered to enhance the optical and electronic properties of the semiconductor. This project involved the designing and fabrication of non-porous and porous GaAs structures using SILVACO TCAD tools. The porous GaAs with different pore depth were designed and simulated to investigate the effect of pore depth on the optical and electrical properties of GaAs semiconductor. The pore depth of porous GaAs structure was varied with 2, 4, 6 and 8 μm. The porous GaAs structures were then tested for the metal-semiconductor-metal (MSM) photodetector device application. The non-porous and porous GaAs MSM photodetectors were compared systematically through current-voltage (I-V) characteristics, current gain, and spectral response. The result showed that the porous GaAs MSM photodetector has better performance in terms of electrical and optical properties than the non-porous photodetector. Amongst the MSM GaAs photodetectors, the porous GaAs photodetector with pore depth of 6 μm obtained the highest current gain value of 3.22. While for optical properties, the spectral response showed the current intensity of 11.370 µA which was recorded at the peak wavelength of 880 nm. Therefore, porous GaAs showed good potential and can be used for optoelectronic device applications such as MSM photodetector.
    Type of Medium: Online Resource
    ISSN: 1662-9795
    URL: Issue
    Language: Unknown
    Publisher: Trans Tech Publications, Ltd.
    Publication Date: 2023
    detail.hit.zdb_id: 2073306-9
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 6
    Online Resource
    Online Resource
    Institute of Advanced Engineering and Science ; 2022
    In:  Indonesian Journal of Electrical Engineering and Computer Science Vol. 28, No. 2 ( 2022-11-01), p. 753-
    In: Indonesian Journal of Electrical Engineering and Computer Science, Institute of Advanced Engineering and Science, Vol. 28, No. 2 ( 2022-11-01), p. 753-
    Abstract: Gender discrimination and awareness are essentially practiced in social, education, workplace, and economic sectors across the globe. A person manifests this attribute naturally in gait, body gesture, facial, including speech. For that reason, automatic gender recognition (AGR) has become an interesting sub-topic in speech recognition systems that can be found in many speech technology applications. However, retrieving salient gender-related information from a speech signal is a challenging problem since speech contains abundant information apart from gender. The paper intends to compare the performance of human vocal tract-based model i.e., linear prediction coefficients (LPC) and human auditory-based model i.e., Mel-frequency cepstral coefficients (MFCC) which are popularly used in other speech recognition tasks by experimentation of optimal feature parameters and classifier’s parameters. The audio data used in this study was obtained from 93 speakers uttering selected words with different vowels. The two feature vectors were tested using two classification algorithms namely, discriminant analysis (DA) and artificial neural network (ANN). Although the experimental results were promising using both feature parameters, the best overall accuracy rate of 97.07% was recorded using MFCC-ANN techniques with almost equal performance for male and female classes.
    Type of Medium: Online Resource
    ISSN: 2502-4760 , 2502-4752
    URL: Issue
    Language: Unknown
    Publisher: Institute of Advanced Engineering and Science
    Publication Date: 2022
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 7
    In: IIUM Medical Journal Malaysia, IIUM Press, Vol. 19, No. 2 ( 2020-10-28)
    Abstract: INTRODUCTION: Poor sleep quality is a common problem experienced by medical students worldwide. Therefore, this study aimed to measure the prevalence of poor sleep quality among medical students in International Islamic University Malaysia (IIUM) and its association with mental health and other factors. MATERIALS AND METHODS: A cross-sectional study using convenience sampling was conducted among 500 medical students in IIUM Kuantan. A validated self-reported questionnaire including sociodemographic, socioeconomic, lifestyle, Pittsburgh Sleep Quality Index and Depression Anxiety Stress Score 21 was distributed from 15th July to 31st August 2019. Descriptive statistics were used to measure the prevalence of poor sleep quality. Chi- square test, Fisher’s exact test, independent sample T-test, and multiple logistic regression were used to measure the association between risk factors and sleep quality. RESULT: The response rate was 91.2%. The prevalence of poor sleep quality was 59.6%. Multiple logistic regression analysis revealed level of study (clinical year (AOR=0.44, 95% CI: 0.29 - 0.66) and depression (yes (AOR: 1.71, 95% CI 1.03-2.83) contributed independently on poor sleep quality among medical students. There was no significant relationship between tahajjud practice and poor sleep quality. CONCLUSION: More than half of IIUM medical students have poor sleep quality. Those students who were in the pre-clinical year and had depression were independently associated with the occurrence of poor sleep quality. Early intervention is compulsory to overcome this problem among medical students in IIUM.  
    Type of Medium: Online Resource
    ISSN: 2735-2285 , 1823-4631
    URL: Issue
    Language: Unknown
    Publisher: IIUM Press
    Publication Date: 2020
    detail.hit.zdb_id: 3038822-3
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 8
    In: IIUM Medical Journal Malaysia, IIUM Press, Vol. 20, No. 4 ( 2021-09-30)
    Abstract: Introduction: Globally, depression is one of the serious problems reported among medical students. Various studies reported that the prevalence of depression among medical students was high due to multiple risk factors. Therefore, this study aimed to measure the prevalence of depression and its associated factors among medical students in International Islamic University Malaysia (IIUM). Materials and Methods: A cross-sectional study was conducted among 500 medical students in IIUM Kuantan. A validated self-reported questionnaire using Depression Anxiety Stress Score 21 was distributed during the second semester of the 2018/2019 session. Descriptive statistics were used to measure the prevalence of depression. Chi-square test, Fisher’s exact test, independent sample T-test, and multiple logistic regression were used to determine the association between risk factors and depression. Result: The prevalence of depression was 39% with 10.5% of them were having severe and extremely severe level of depression. Multiple logistic regression analysis showed regular physical activity (AOR=0.64, 95% CI: 0.42-0.98) and Tahajjud prayer practice (AOR: 0.76, 95% CI 0.66-0.88) are two protective factors against depression among medical students. Conclusion: About two out of every five IIUM medical students had depression. Regular physical activity and Tahajjud prayer practised may reduce the risk of depression and should be encouraged.
    Type of Medium: Online Resource
    ISSN: 2735-2285 , 1823-4631
    URL: Issue
    Language: Unknown
    Publisher: IIUM Press
    Publication Date: 2021
    detail.hit.zdb_id: 3038822-3
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 9
    In: Journal of Electronic Voltage and Application, Penerbit UTHM, Vol. 3, No. 2 ( 2022-12-29)
    Abstract: Finding parking spotsfor automobiles is a major issue in many large and congested cities. Usually, drivers lose time searching for parking spots, especially during peak hours, which increases traffic congestion and makes drivers frustrated and annoyed. Large building parking areascould also become dangerous to women, pregnant women,and the elderly, as several criminal cases in the parking area,werereported. In this project, a prototype of a smart parking spot allocation system based on the user’s category and priority was developed. The choiceofusercategories ispeople with disabilities (OKU), pregnant women/elderly, women,and normal users. Thehighest priority is assigned to OKU, followed by pregnant women/elderly, followed by women and the lowest priority is assigned tonormal users. The parking spots for the highest priority category are placed near building entrances such as mall entrances. The controller for the automatic parking spot allocation system wasdeveloped using Verilog HDL code and the prototype wasimplemented on FPGA DE2-115. The controller is programmed to process the user’s category which is selected by the userat the second entrance and assign a specific parking spot number according to the category’s priority. The prototype was tested with multiple parking spots condition with different userinputsfor different usercategories. The system was able to allocate parking spotsbased on the user’s category depending on the parking spot availablefor the selected categorywith 75% out of 12 tests correct.However, all 12 tests,or 100% recorded accurate allocation based on the expected output of the system design.Ina conclusion,this proposed system would beable to cater to the issue offinding parking spots hence directly avoidingtraffic congestion and frustration among users. In addition, this system can indirectly reduce crime cases in the parking area due to parking spaces that prioritize categories of users needingto be parked near the entrance.
    Type of Medium: Online Resource
    ISSN: 2716-6074
    URL: Issue
    Language: Unknown
    Publisher: Penerbit UTHM
    Publication Date: 2022
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 10
    In: Advanced Materials Research, Trans Tech Publications, Ltd., Vol. 364 ( 2011-10), p. 105-109
    Abstract: Sol-gel spin coated PMMA:TiO 2 nanocomposite thin films on glass substrates were studied by comparing two types of the sol-gel solutions. Two types of PMMA:TiO 2 nanocomposite sol-gel solutions were prepared; one using Degusa (P25), and the other one is using self-prepared TiO 2 powder. The self-prepared nanosized TiO 2 powder is obtained by drying the TiO 2 sol-gel using solvothermal method followed by grinding the TiO 2 crystal using ball miller. Triton-X was used as surfactant to stabilize the composite. Besides comparing the nanocomposite solution, we also studied the effect of the thin films thickness on the optical properties and their surface morphology. The optical properties and surface morphology were measured with UV-VIS spectrometer and atomic force microscopy (AFM). The result showed that nanocomposite PMMA with self-prepared TiO 2 give high optical transparency than that of with Degusa (P25). The results also indicate that as the thickness is increased the optical transparency are decreased. Both AFM images showed that the agglomerations of TiO 2 particles occurred on top of the thin film and the surface roughness increased when the thickness is increased. AFM results show that nanocomposited PMMA with P25 has high agglomeration particles compared to the other one.
    Type of Medium: Online Resource
    ISSN: 1662-8985
    URL: Issue
    Language: Unknown
    Publisher: Trans Tech Publications, Ltd.
    Publication Date: 2011
    detail.hit.zdb_id: 2265002-7
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...