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Manipulating membrane hydrophobicity by integrating polythylene-coated fume silica in PVDF membrane
Get PDFMembrane gas absorption (MGA) as an emerging technology exhibits superior advantages in comparison to conventional carbon dioxide (CO2) absorption processes. However, the decrease in membrane flux, induced by membrane wetting is a significant issue to be pondered upon. Thus, fabrication of an antiwetting composite membrane is essential to retain and sustain the MGA performance. In this work, silica nanoparticles (SiNPs) is first coated with hydrophobic low-density polyethylene (LDPE). Then, integrating LDPE-HMDS/SiNPs fillers into the polyvinylidene fluoride (PVDF) matrix to increase its hydrophobicity. The incorporation of LDPE-coated silica into PVDF polymer enhanced the contact angle values from 71.8° to 111.8°, indicates the improvement of membrane anti-wetting ability. Despite the similar finger-like layer laid on top of the sponge-like structure for pristine and composite membranes, the incorporation of LDPE-HMDS/SiNPs has reduced in the length ratio of finger-like to sponge-like layer. The changed in the membrane morphology induced higher membrane hydrophobicity which prevent membrane from getting wet easily especially in long term of operation. In addition, EDX surface mapping and lining profiles clearly proved that the LDPE-HMDS/SiNPs were distributed evenly in the composite membranes indicates the good interfacial compatibility between PVDF polymer and LDPE-coated silica. In term of CO2 absorption flux, the embedment of LDPE-HMDS/SiNPs in PVDF polymer matrix demonstrated 2.4x10-3 mol/m2.s which was 2 times higher than that of the pristine membrane. This means the incorporation of LDPE-HMDS/SiNPs into the PVDF membrane has still played a pivotal role in overcoming membrane wetting drawbacks when in contact with the liquid absorbents
Optimisation of cogeneration energy system in an industrial park using cooperative game theory
No full textCogeneration or combined heat and power (CHP) is a proven energy-efficient technology for its ability to generate electricity and heat energies concurrently. In an industrial park, implementing the cogeneration energy system by different facilities requires a symbiosis synergy to determine the optimal design. Previous works have studied the cooperative coalition among tenants in an eco-industrial park. In this paper, the cooperative game theory explores the potential coalition between different facilities for optimal cogeneration implementation. The integrated optimisation framework is proposed to (1) minimise the overall cost and environmental emission constraints and (2) rationally allocate the investment costs and profits among the collaborating parties. The optimisation problem is solved as a mixed-integer linear programming (MILP) model by using GAMS software. The obtained optimal coalition has a TAC of RM 7.85 x 106/y and assigns the iron-fabricating facility with a heat-to-power ratio of 2 as the anchor entity. The developed framework is crucial to laying the groundwork for macro-level cogeneration and peer-to-peer electricity trading planning in Malaysia
Tacit knowledge in instructional leadership: evidence from Malaysian secondary principals
Get PDFAlthough there is a plethora of studies related to principals’ instructional leadership practice, little attempt has been made to understand their tacit knowledge in this area. Thus, the key purpose of this study is to understand whether Malaysian principals have in-depth knowledge on instructional leadership practice as it is highly emphasised in the Malaysia’s Education Blueprint policy. A total of 202 secondary principals have provided their feedback on their tacit knowledge related to instructional leadership practice. Later, their answers were compared with suggestions from instructional leadership models to see if they coincided. In measuring secondary principals’ tacit knowledge, results indicated that secondary principals have in-depth knowledge on instructional leadership as they achieved a score of over 80 per cent correct answers for 13 out of 15 items to which they were asked to respond. In terms of significant differences, the non-parametric results indicated that there are differences in terms of their experiences in practising instructional leadership. The significant differences were indicated between senior with novice principals with a non-significant difference from principals’ gender and age. Finally, this indicates that principals’ tacit knowledge on instructional leadership was influenced by their leadership experience and age. There are suggestions and recommendations concerning the practical implications of principals’ benefitting from practising instructional leadership
Exploring teacher effects on intensifying and minimizing mathematics anxiety among students in Sokoto State, Nigeria
Get PDFMathematics anxiety is the feeling of tension and fear which interferes with the manipulation of numbers in ordinary life and academic setting. This study aimed at exploring students’ level of mathematics anxiety and teacher behavior and speech which intensifies and minimizes mathematics anxiety among secondary schools in Sokoto state, Nigeria. In total, 109 questionnaires regarding mathematics anxiety named the cognitive, emotion, physical-mathematics anxiety rating (CEP-MAR) were distributed to students and 102 were returned. From the responses in the questionnaire, 20 of the most mathematics anxious individuals were selected to participate in a photovoice project. These 20 students were given cameras and asked to capture classroom events, which impact on their mathematics anxiety. Afterwards, a one-to-one semi-structured interview was conducted with each student to discuss the photos. The findings disclosed that teachers’ behavior and speech such as being too quick in mathematics classroom lessons, giving too many notes, exercises, punishments and embarrassing/alarming statements have a significant effect in intensifying mathematics anxiety. The findings also showcased that quiz/competitions, good learning environment, intrinsic and extrinsic motivational statements help in minimizing mathematics anxiety. This study provides further evidence that teachers have both positive and negative effect on students’ mathematics anxiety
Potentiality of MWCNT on 3D-printed bio-inspired spherical-roof cubic core under quasi-static loading
No full textSandwich panel is increasingly used as lightweight energy absorbing components, which provides excellent crashworthiness performance with the three-dimensional periodic core. This paper investigates 3D-printed bio-inspired spherical-roof cubic cores with multi-walled carbon nanotubes (MWCNT) and foam-filled cores under quasi-static loading. The proposed bio-inspired spherical-roof cubic cores with 1.5 mm wall thickness were manufactured using the fused filament fabrication process, which used 70% polylactic acid (PLA) and 30% carbon fiber filament. Moreover, four groups of 3D-printed bio-inspired spherical-roof cubic cores were compared and analyzed on compressive properties and failure behavior. Experimental results were shown that foam-filled double bio-inspired spherical-roof cubic core with MWCNT was the maximum Fpeak with 1.92 kN, which provided a much more stable plateau load and better energy-absorbing characteristics. In addition, it is conducted that a double bio-inspired spherical-roof cubic core with four notches core is considered as the potential energy-absorbing core
Influence of solution heat treatment on microstructure and tensile properties of gd-treated al-15% mg2si in-situ composites
No full textMicrostructural alteration and tensile properties of Al-15% Mg2Si composite specimens was examined after addition of gadolinium (Gd) and conducting solution heat treatment. Various percentages of gadolinium (0.5, 1.0, 2.0 and 5.0 wt. % Gd) were added to the composite Al-15% Mg2Si composite. The specimens then solutionized at 500 degrees C for 4h followed by quenching. The results showed that regular morphology and small size of primary Mg2Si particles is achieved after addition of 1.0 wt.% Gd compared to untreated composite. Due to solutionizing effect, Mg2Si dissolution occurred which led to alter the morphology of primary Mg2Si particles to round shape. Tensile testing results revealed that enhancement in UTS and El% values owns to influence of both Gd addition and solution heat treatment on the Al-15% Mg2Si composite. The fracture surface of untreated composite depicted a cellular fracture, while the fracture surface of Gd treated and heat treated composite showed a ductile surface containing fine dimples, in which alteration of fracture mode is due to the role of Gd and heat treatment on microstructural modification, which results in reduction of potential sites for stress concentration and crack initiation areas
Hybrid microchannel heat sink with sustainable cooling solutions: numerical model validation
No full textMiniaturization and utilization of low-dimensional structures of recent electronic devices have witnessed some new micro cooling methods which can fulfil the cooling demand for the electronic devices. Microchannel heat sink (MCHS) is one of the micro cooling method which appears as a promising method that can provide high heat transfer rate due to small hydraulic diameter. Furthermore, microchannel heat sink is easy to be fabricated compare to other micro cooling device. Due to fast development in electronic industry, hybrid microchannel heat sink with optimal design has received a great deal of attention in order to provide sustainable cooling solutions. However, most of the studies of hybrid microchannel heat sink only provided the numerical analysis without any validation of the proposed design experimentally. This is very important since it also will determine whether the proposed hybrid microchannel heat sink can be fabricated or not. Therefore, the aim of this article is to validate the numerical model of hybrid microchannel heat sink (TC-RR-SC MCHS) experimentally. The validation result showed that the maximum discrepancy between both simulation and experimental analyses for Nusselt number and friction factor were 15.8% and 17.4%, respectively, which is less than 20%. The different number of microchannels between the simulated TC-RR-SC MCHS and fabricated TC-RR-SC MCHS is one of the factors that contribute to the data discrepancy. Furthermore, the poor finishing during the fabrication process also another factor because the burrs and debris at the top and bottom surface of microchannels affect the convective heat transfer area and the flow area of fluid
The blockage ratio effect to the spray performances
Get PDFNozzle sprays are used in wide range of application. The used of nozzle application is depend on the spray characteristics, by which to suit the particular application. This project studies the effect of the air blockage ratio to the spray characteristics. This research conducted into two part which are experimental and simulation section. The experimental was conducted by using particle image velocimetry (PIV) method, and ANSYS software was used as tools for simulation section. There are two nozzles were tested at 1 bar pressure of water and air. Nozzle A (with blockage ratio 0.316) and nozzle B (blockage ratio 1.000). Both of the sprays performances generated by the nozzles was examined at 9 cm vertical line from 8 cm of the nozzle orifice. The validation result provided in the detailed analysis shows that the trend of graph velocity versus distance gives the good agreement within simulation and experiment. From result, nozzle A generated a wider spray angle and higher water droplet velocity which are 31.41 degree and 37.317 m/s compared to nozzle B which has produced 27.13 degree of spray penetration angle and 16.49 m/s water droplet velocity. As a conclusion, blockage ratio has affected the spray system by increasing the velocity of air inside the spray system. This is happened at a condition of 1 bar air pressure
The influence of coal bottom ash as filler in asphalt mixture
No full textThe number of transport or vehicles on the road increases, which causes the road pavement or asphalt surface to be exposed to greater loading. Problems such as permanent deformation, cracking, fatigue, and skidding happened because of this repeated loading. Many studies have been done to determine the suitable waste materials that can be used to improve resistance to rutting and fatigue cracking due to filler hardening and improve adhesion of filler to aggregate. The aim of this study is to investigate the effect of coal bottom ash on the engineering properties of the asphalt mixture. The different percentages of coal bottom ash (0%, 2%, 4% and 6%) were added to the asphalt mixture. The 60/70 penetration grade asphalt was used. The performance of the samples was evaluated through Marshall Stability, indirect tensile strength, resilient modulus, dynamic creep and image analysis. From the result obtained, there are significant effect comes from the addition of coal bottom ash. The result shows that the addition of coal bottom ash in the range of 2 to 4% produces the best outcomes for the density, stability, stiffness and flow while 6% for indirect tensile strength, dynamic creep and resilient modulus. Thus, it can be concluded that the existence of coal bottom ash can enhance the performance of the asphalt mix
Trend in the study of intercultural competence: bibliometric analysis by citespace
No full textThe literature search has shown that the number of research materials associated with intercultural competence has been increasing gradually over the past twenty years. And this apparently shows that a systematic review of intercultural competence is essential for researchers and the aim of this paper is to discuss the trend of transition in intercultural communication studies from the notion of “intercultural competence”, followed by “intercultural communication competence” and the latest notion is “intercultural communicative competence”. In doing so, the Scopus database was adopted, by which the analysis was carried out on the keywords and their diachronic development with retrieval of materials published with the keywords used were “intercultural communication competence” or “intercultural communicative competence” by periodicals from 1970 to 2021. The findings show that the acronym ICC is used to represent all the three notions. Most importantly, the three representative notions emerge in different time but with continuous trait in the study of intercultural communication. Further, the main research aspects are identified in the domain of “education”, involving in “higher education”, “student”, and “human experiment” as well as “study abroad”. The findings of bibliometric analysis provide a more specific insights into the term selection of intercultural communicative competence, its main research aspects, diachronic development and future research direction