Enhancement of Thermoelectric Properties in Cold Pressed Nickel Doped Bismuth Sulfide Compounds

Fitriani Fitriani,Suhana Mohd Said,Shaifulazuar Rozali,Mohd Faiz Mohd Salleh,Mohd Faizul Mohd Sabri,Duc Long Bui,Tadachika Nakayama,Ovik Raihan,Megat Muhammad Ikhsan Megat Hasnan,Mohamed Bashir Ali Ba 대한금속·재료학회 2018 ELECTRONIC MATERIALS LETTERS Vol.14 No.6

Nanostructured Ni doped Bi 2 S 3 (Bi 2−x Ni x S 3 , 0 ≤ x ≤ 0.07) is explored as a candidate for telluride free thermoelectric material,through a combination process of mechanical alloying with subsequent consolidation by cold pressing followed with asintering process. The cold pressing method was found to impact the thermoelectric properties in two ways: (1) introductionof the dopant atom in the interstitial sites of the crystal lattice which results in an increase in carrier concentration, and (2)introduction of a porous structure which reduces the thermal conductivity. The electrical resistivity of Bi 2 S 3 was decreasedby adding Ni atoms, which shows a minimum value of 2.35 × 10 −3 Ω m at 300 °C for Bi 1.99 Ni 0.01 S 3 sample. The presenceof porous structures gives a signifi cant eff ect on reduction of thermal conductivity, by a reduction of ~ 59.6% compared toa high density Bi 2 S 3 . The thermal conductivity of Bi 2−x Ni x S 3 ranges from 0.31 to 0.52 W/m K in the temperature range of27 °C (RT) to 300 °C with the lowest κ values of Bi 2 S 3 compared to the previous works. A maximum ZT value of 0.13 at300 °C was achieved for Bi 1.99 Ni 0.01 S 3 sample, which is about 2.6 times higher than (0.05) of Bi 2 S 3 sample. This work showan optimization pathway to improve thermoelectric performance of Bi 2 S 3 through Ni doping and introduction of porosity.

A Design and Development of a Wireless Sensor Network for Potential Monitoring and Localization

Nurul Amira Mohd Ramli,Mohd Hafiz Fazalul Rahiman,Muhammad Faiz Abdul Malik,Latifah Munirah Kamarudin,Latifah Mohamed,Ammar Zakaria,Mohammed Saeed Moqbel Abdullah 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.6

This paper presents an analysis of the received signal strength indicator (RSSI) from the radio frequency signals for human identifi cation in an indoor wireless sensor network (WSN). Instead of using closed-circuit television as the existing security platform, this indoor safety system was improved with a convenient, cheap, and low-power solution. The system was developed using 20 of ESP8266-12F Wi-Fi modules transmitters and another 2 of ESP8266-12F as the access points located in 3 m × 3 m area of interest. With a suitable coordinate of sensor nodes, a WSN telemetry could be established to minimize the blind spot area and limit the movement of the intruder with a minimum area of 0.2 m 2 . The RSSI measurement was repeatedly conducted for three diff erent conditions, in an empty room, with the presence of a single intruder and the presence of multiple intruders. Based on the RSSI values, we found that there are distinctive features of data that can be utilized as fl ags for classifying the three above conditions. Besides that, to justify the effi ciency of system performance, we also examined the sensitivity of RSSI values towards the variation of temperature. Our results show that the RSSI average values for both morning and night were practically the same. However, during the afternoon, the RSSI signal strength fl uctuated by − 1.0 dBm. These results motivate the development of an alarm system that only uses the RSSI statistics to detect human presence.

A Low-Profile Quasi-Loop Magneto-Electric Dipole Antenna Featuring a Wide Bandwidth and Circular Polarization for 5G mmWave Device-to-Device Communication

Kamal Shahanawaz,Ain Mohd Fadzil Bin,Ullah Ubaid,Mohammed Abdullahi S. B.,Hussin Roslina,Omar Mohamad Faiz Bin Mohamed,Najmi Fathul,Ahmad Zainal Arifin,Rahman Mohd Fariz Ab,Mahmud Mohd Nazri,Othman Mo 한국전자파학회 2022 Journal of Electromagnetic Engineering and Science Vol.22 No.4

The deployment of the millimeter (mmWave) frequency spectrum by fifth-generation (5G) device-to-device (D2D) wireless networks is anticipated to meet the growing demands for increased capacity. The antenna is regarded of as an important determinant that guarantees the maximum performance of wireless communication. This paper presents a low-profile magneto-electric (ME) dipole antenna for 5G mmWave D2D communication. A single-element quasi-loop radiator was designed to excite horizontal polarization, and a coaxial probe was used to produce vertical polarization. Subsequently, the structure of the radiator was transformed into a two-element quasi-loop an- tenna to achieve an omnidirectional radiation pattern with relatively enhanced gain. A coaxially fed T-junction microstrip element was implemented to equally distribute the signal between the two quasi-loop radiators and attain proper impedance matching. Furthermore, a pair of shorting pins was introduced into the two-element design to maintain the circularly polarized (CP) radiation. The finest values of the axial ratio and |S11| were derived by rigorously optimizing all the geometry parameters. Both single-element and two-element quasi- loop antennas were fabricated and characterized experimentally on the air substrate. The advantage of avoiding a physical substrate is to realize a wide bandwidth, circumvent dielectric losses, and ascertain the maximum gain. The measured and simulated results agree thor- oughly with each other. Stable in-band CP radiation were accomplished, thus confirming an appropriate field vector combination from the coaxial probe and the radiator. The finalized antenna engaged an area of ~7.6λ for operation at 23.9–30.0 GHz with an axial ratio <3 dB, radiation efficiency ~80%, and gain >5 dBic.

Carbon precursor analysis for catalytic growth of carbon nanotube in flame synthesis based on semi-empirical approach

Zainal Muhammad Thalhah,Mohd Yasin Mohd Fairus,Wan Ali Wan Fahmin Faiz,Tamrin Khairul Fikri,Ani Mohd Hanafi 한국탄소학회 2020 Carbon Letters Vol.30 No.5

Although fame synthesis promises economic beneft and rapid synthesis of carbon nanotube (CNT), the lack of control and understanding of the efects of fame parameters (e.g., temperature and precursor composition) impose some challenges in modelling and identifying CNT growth region for obtaining better throughput. The present study presents an investigation on the types of carbon precursor that afect CNT growth region on nickel catalyst particles in an ethylene inverse difusion fame. An established CNT growth rate model that describes physical growth of CNT is utilised to predict CNT length and growth region using empirical inputs of fame temperature and species composition from the literature. Two variations of the model are employed to determine the dominant precursor for CNT growth which are the constant adsorption activation energy (CAAE) model and the varying adsorption activation energy (VAAE) model. The carbon precursors investigated include ethylene, acetylene, and carbon monoxide as base precursors and all possible combinations of the base precursors. In the CAAE model, the activation energy for adsorption of carbon precursor species on catalyst surface Ea,1 is held constant whereas in the VAAE model, Ea,1 is varied based on the investigated precursor. The sensitivity of the growth rate model is demonstrated by comparing the shifting of predicted growth regions between the CAAE model and the VAAE model where the CAAE model serves as a control case. Midpoint-based and threshold-based techniques are employed within each model to quantify the predicted CNT growth region. Growth region prediction based on the midpoint-VAAE approach demonstrates the importance of acetylene and carbon monoxide to some extent towards CNT growth. Ultimately, the threshold-VAAE model shows that the dominant precursor for CNT growth is the mixture of acetylene and carbon monoxide. A simplifed reaction mechanism is proposed to describe the surface chemistry for precursor reactions with nickel catalyst where decomposition of the ethylene fuel source into acetylene and carbon monoxide is accounted for by chemisorption.

Comparison of Early Succession and Scleractinian Recruitment Between Artificial Live Rocks and Terracotta Tiles

Hamizan Yusof Muhammad,Saad Shahbudin,Naim Mohd Azrul,Khodzori Mohd Fikri Akmal,Hanapiah Muhammad Faiz Mohd 한국해양과학기술원 2021 Ocean science journal Vol.56 No.3

Previous studies indicated that artificial live rock (ALR) has the potential to be used as a substrate for coral juveniles. The present study reported a potential of ALR as an ideal substrate for future artificial reef structure. This study was conducted at three sampling sites, namely Teluk Salang, Teluk Bakau and Teluk Sanggit in Tioman Island, Pahang, Malaysia. The total of 96 samples of ALR (n = 48) and terracotta tiles (n = 48) were deployed and periodically retrieved with three-month interval for 15 months. Retrieved settlement plates were analyzed to compare the total abundance of epibionts and coral density between ALR and tiles. Results showed that ALR plates exhibited a significantly higher total benthic abundance compared to terracotta tile [Independent T-Test; t (22) = 2.650, p = 0.015]. On average, a total of 82.8 ± 5.2% of benthic organisms covered ALR’s surfaces compared to terracotta tiles with 62.5 ± 5.6%. The number of coral spats was significantly higher on ALR by 60.7 ± 10.7% compared to terracotta tiles [Mann–Whitney U Test; U = 10.5, p = 0.003]. In addition, there was a significant difference between sites in the abundance of epibionts as determined by one-way ANOVA [F (2,21) = 11.945, p < 0.001] for both substrates. However, Kruskal–Wallis H test showed that there was no significant difference in terms of coral density at the sites of deployment [H (2) = 3.730, p = 0.155]. The results demonstrated ALR as a new suitable settlement substrate for benthic organisms which can be applied as a substrate for artificial reef, coral propagation and coral transplant.

Self-Cleaning Antifouling Performance Based on the Surface Area of Flower-Like TiO2 as Additive for PSf Mixed Matrix Membrane

Faiz Hafeez Azhar,Zawati Harun,Siti Salwa Alias,Muhamad Zaini Yunos,Siti Aida Ibrahim,Tijjani Abdullahi,Azlinnorazia Ahmad,Mohd Hafiz Dzarfan Othman 한국고분자학회 2020 Macromolecular Research Vol.28 No.6

The photocatalytic polymer mixed matrix membrane (MMM) has been widely used for the separation and purification process. The objective of this study is to investigate the effect of structural TiO2 (synthetic TiO2 (ST), flower-like TiO2-100 (FLT-100), and flower-like TiO2-600 (FLT-600)) based on the total surface area for the efficient self-cleaning antifouling property. The asymmetric MMMs were fabricated using the phase inversion process with a different type of structural TiO2 as additive. As a result, the addition of synthesized FLT, especially FLT-100, has influenced the hydrophilicity and surface roughness of the MMM. From the powder analysis, FLT-100 exhibits the highest total surface area with 37.25 m2/g and strongly affects the self-cleaning antifouling performance of the MMM. This membrane produced the highest self-cleaning efficiency (68.8%) compared to FLT-600 (58%) and ST (39.8%) after UV exposure, thus, indicates in a better self-cleaning antifouling property that offers the potential to be considered for commercialization in reducing the maintenance cost by using both physical and chemical cleaning method that becomes a problem in membrane technologies.

Dodecylbenzenesulfonic acid micelles assisted in situ preparation and enhanced thermoelectric performance of semiconducting polyaniline–zirconium oxide nanocomposites

Tarique Anwer,Faiz Mohammad,Mohd Omaish Ansari 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.5

Herein, we report in situ preparation of dodecylbenzenesulfonic acid (DBSA) micelles assisted polyaniline (Pani)/zirconium oxide (ZrO2) nanocomposites (Pani/ZrO2) by using K2S2O8 as an oxidizing agent. Thus prepared nanocomposites were characterized by SEM, FTIR, XRD and UV–vis spectropho-tometry. DBSA acted as dopant/surfactant, and the incorporation of ZrO2 nanoparticles improved the stability, electrical and thermal properties of nanocomposites. From the results of UV–vis absorbance it was observed that Pani/ZrO2 nanocomposite was more stabilized under UV light than Pani. DC electrical conductivity retention was studied by isothermal and cyclic ageing techniques and was observed to be better than Pani under ambient environmental conditions.

Assessment of Meta-Heuristic and Classical Methods for GMPPT of PV System

M. Naseem,Mohammed Aslam Husain,Ahmad Faiz Minai,Ahmad Neyaz Khan,Mohd Amir,J. Dinesh Kumar,Arif Iqbal 한국전기전자재료학회 2021 Transactions on Electrical and Electronic Material Vol.22 No.3

Numerous global peak searching mechanisms have been proposed to solve the problem of energy loss due to partial shading of solar photovoltaic (PV) plants but still there is a great need for an effi cient and fast global maximum power point tracker (GMPPT). A detailed review of GMPPT based on various meta-heuristic and classical methods along with the basics of partial shading phenomenon, proper positioning of the PV panels, distributed MPPT, Field MPPT etc. will be of great help to the researchers. Till date, it looks like that not a single literature has covered these issues at a single place and thus, this article fi lls this gap by providing a detailed assessment, tabulated gist of the various GMPPT along with the basics of key issues related to partial shading of PV plants. Various classical and bio-inspired meta-heuristic based GMPPT methods have been compared in this literature. It is expected that this paper will prove to be a valuable asset and a complete reference for the academicians and professionals for further research and proper selection of a GMPPT technique.

Current Status of Coral Reef Fish Abundances at Pulau Bidong and Nearby Islands, South China Sea Using Stereo-Diver Operated Video System

Afiq-Firdaus Aminudin Muhammad,Safuan Che Din Mohd,Shafie Suhaidi,Izhar Lila Iznita,Awalludin Ezmahamrul Afreen,Ahmad Muhammad Faiz,Johari Nur Arbaeen Mohd,Bachok Zainudin 한국해양과학기술원 2023 Ocean science journal Vol.58 No.2

Tropical coral reef fish assemblages in the South China Sea (SCS) have not been well-studied; thus, this research investigated the species richness of coral reef fishes at Pulau Bidong and the surrounding islands of Terengganu, Malaysia. Fish surveys were conducted using the Stereo-Diver Operated Video System (Stereo-DOVs) technique from July to October 2019 at 14 sites with different underwater reef structural features. A total of 8259 individuals and 52 reef fish species belonging to 14 families with a density of 23.597 ind. m− 3 were identified and counted from the surveys. Among the families, Scaridae (parrotfish— herbivore), Labridae (wrasse—invertivore), Serranidae (grouper—carnivore), Lutjanidae (snapper—carnivore), and Chaetodontidae (butterflyfish—corallivore) were commonly recognized as indicator fishes for reef health. Based on trophic groups, the proportion of herbivores was significantly highest (51%), followed by carnivores (26%), invertivores (21%) and corallivores (2%). Among the indicator species, Scarus psittacus (Scaridae—parrotfish; Common Parrotfish, 0.829 ind. m− 3) was predominant, followed by Lutjanus lutjanus (Lutjanidae—snapper; Bigeye Snapper, 0.463 ind. m− 3) and Thalassoma lunare (Labridae—wrasse; Moon Wrasse, 0.229 ind. m− 3). The fish communities found at each station were 80% similar between locations. The density at each station ranged from 0.280 to 4.834 ind. m− 3, the diversity index (H′) recorded was between 2.186 and 3.492 and evenness (J′) ranged from 0.610 to 0.862. The high abundance and diversity and significant proportion of indicator fishes might indicate that the coral reef ecosystems at Pulau Bidong and surrounding islands are in good condition. This study offers significant ecological data on fish assemblages of tropical coral reef ecosystems, specifically in the SCS region on the east coast of Peninsular Malaysia.

Role of mixing mediums in the synthesis of single phase CaCu3Ti4O12 (CCTO)

Rosyaini Afindi Zaman,Wan Fahmin Faiz Wan Ali,Mohamad Johari Abu,Julie Juliewatty Mohamed,Mohd. Fadzil Ain,Zainal Arifin Ahmad 한양대학교 세라믹연구소 2016 Journal of Ceramic Processing Research Vol.17 No.6

The role of mixing mediums on synthesizing high purity CCTO as a function of calcination temperature was systematicallyinvestigated via solid state reaction (SSR) route. The efficacy of the mediums (ethanol, deionised water, distilled water, and drymix) was primarily determined by X-ray diffraction (XRD) technique and FESEM, respectively. It is found that, a single phaseCCTO was successfully synthesized in all mediums, with the deionised water showed the lowest reaction temperature (950 oC)to fully crystallize the powder mixtures compared to other mediums. No significant changes were seen in the grain shape sinceonly a bimodal structure with grain size ranging from 0.5 μm to 2.57 μm was observed. The effect of media was also seen intheir dielectric properties of the calcined powders. Dry mixing (DM) had the highest dielectric permittivity (εr = 118) whereasothers are only between 59-99. Therefore, this observation proved that mixing medium could influence the formationtemperature and dielectric properties of CCTO.