19672 research outputs found
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Experimental and simulation investigation into the effects of a flat plate deflector on vertical axis wind turbine
No full textPower augmentation features have been proven as one of the wind turbine performance enhancement methods particularly for vertical axis wind turbines (VAWTs). Researches showed that with the aid of a deflector, shroud or a single plate, the power output of a VAWT can be increased remarkably. In this paper, lab tests and simulations were performed to investigate the aerodynamic effects and the flow field around a flat plate deflector as a power augmentation device which is placed at the lower upstream of a micro H-rotor VAWT. From the study, the deflector is able to induce a high velocity wind at the near-wake region which was about 25% higher compared to the oncoming wind velocity. The deflected wind flows improve the performance significantly as well as reduce the self-start velocity of the turbine. Nonetheless, it is highly dependent on the positioning of the flat plate deflector. Both experiment and simulation showed a notable observation on the position effect of the flat plate deflector. From the lab test, with the deflector at the optimal position, the maximum coefficient of power (CP) achieved was 7.4% increment compared to the bare turbine. Also, from the simulation, the optimal position showed an improvement of averaged CP up to 33% compared to the bare turbine. The flat plate deflector is simple, low cost, and can be easily retrofitted to existing stand-alone VAWT systems to improve the efficiency making them suitable for on-site power generation in urban and isolated places
Knowledge Structures of City Innovation Systems: Singapore and Hong Kong
No full textCities are naturally the center of attention when innovation and its geography are discussed. This paper seeks to elucidate the knowledge structures of the city innovation systems of Hong Kong and Singapore, and shed light on the performance of knowledge production, networks, and features in accordance with: (1) patent portfolios and fields of technology; (2) the patent landscape; and (3) the correlation map between fields and entities that produce patents. Findings indicate that private firms dominate the patenting landscape for the selected economies. Scientific activities performed by universities and public research institutions are converging with technological knowledge performed by firms. Hong Kong and Singapore sought to attain a co-evolution process for science-based industrial development
MobiCoRE: Mobile Device Based Cloudlet Resource Enhancement for Optimal Task Response
No full textCloudlets are small self maintained clouds, with hotspot like deployment, to enhance the computational capabilities of the mobile devices. The limited resources of cloudlets can become heavily loaded during peak utilization. Consequently, per user available computational capacity decreases and at times mobile devices find no execution time benefit for using the cloudlet. Researchers have proposed augmenting the cloudlet resources using mobile devices; however, the proposed approaches do not consider the offered service to load ratio while using mobile device resources. In this paper, we propose easy to implement Mobile Device based Cloudlet Resource Enhancement (MobiCoRE) while ensuring that: (i) mobile device always have time benefit for its tasks submitted to the cloudlet and (ii) cloudlet induced mobile device load is a fraction of its own service requirement from the cloudlet. We map MobiCoRE on M/M/c/K queue and model the system using birth death markov chain. Given the arrival rate of λ, c cpu cores in cloudlet, maximum tasks in the cloudlet to be K and P0=f(λ c,K,μ) be probability of having no user in cloudlet, we derive the condition fracλ}{cK-cμ1000 for optimal average service time 1μ of cloudlet such that the mobile applications have maximum benefit for using cloudlet services. We show that the optimal average service time is independent of the applications service requirement. Evaluation shows that MobiCoRE can accommodate upto 50 percent extra users when operating at optimal service time and sharing mobile resources for remaining task, compared to completing the entire user applications in cloudlet. Similarly, up to 47 percent time benefit can be achieved for mobile devices by sharing only 16 percent computational resources with the cloudlet
Preliminary Performance Tests and Simulation of a V-Shape Roof Guide Vane Mounted on an Eco-Roof System
No full textThe technical and economic features of a patented V-shape roof guide vane (VRGV) with a solar and wind power generation system mounted on an eco-roof system are presented in this paper. Moreover, this innovative VRGV was investigated on for the purpose of improving the performance of a vertical axis wind turbine (VAWT), which was installed on an eco-roof system to solve the low-efficiency power generation problem of the wind turbines under the condition of a low wind speed. This paper proposes a preliminary study for the performance of the VAWT with the VRGV on a building. This research used a mock-up building with a double slope roof, where a five straight-bladed VAWT was mounted and tested under two conditions, with and without the VRGV. From the comparative experiments, the self-starting performance and rotational speed of the VAWT mounted above a double slope roof with the VRGV have been significantly improved compared to the VAWT without the VRGV. Further, the power coefficient (Cp) of the VAWT can be augmented to about 71.2% increment due to the VRGV design. In addition, numerical simulations by computational fluid dynamics (CFD) were proposed to verify the augmented effect of the Cp of the VAWT under the influence of the VRGV in the experiment. Besides, economic estimation of the VRGV was conducted
Novel bufferless photosynthetic microbial fuel cell (PMFCs) for enhanced electrochemical performance
No full textPhotosynthetic microbial fuel cells (PMFCs) are novel bioelectrochemical transducers that employ microalgae to generate oxygen, organic metabolites and electrons. Conventional PMFCs employ non-eco-friendly membranes, catalysts and phosphate buffer solution. Eliminating the membrane, buffer and catalyst can make the MFC a practical possibility. Therefore, single chambered (SPMFC) were constructed and operated at different recirculation flow rates (0, 40 and 240 ml/min) under bufferless conditions. Furthermore, maximum power density of 4.06 mW/m2, current density of 46.34 mA/m2 and open circuit potential of 0.43 V and low internal resistance of 611.8 Ω were obtained at 40 ml/min. Based on the results it was decided that SPMFC was better for operation at 40 ml/min. Therefore, these findings provided progressive insights for future pilot and industrial scale studies of PMFCs
Social Media for Empowerment in Social Movements: The Case of Malaysia's Grassroots Activism
No full textSocial media plays an instrumental role in enabling and facilitating social movements. However, this role depends on the complex social issues in a civic community and dynamics of power in movement politics. Existing literature provides little insight into the formative role of social media in social movements; instead, it tends to focus on the informational role and episodic effect of social media in community activism. We present the case of Bersih, a social media-enabled social movement that pushed for electoral reform in Malaysia. The non-partisan community-driven movement exerted public pressure on institutions and gained formal recognition. In this study, we reveal the significant role social media plays in empowering citizens by enabling them to facilitate and coordinate collective action towards producing change in their community. This research is significant in articulating the precise nature of the role of ICT in addressing complex social problems
Effect of phase-based instruction using geometer's sketchpad on geometric thinking regarding angles
No full textTeaching and learning geometry is not merely about memorising geometrical properties but about grasping the conceptual understanding of geometry as well. Students, however, face challenges in the classroom trying to develop their geometrical thinking. The purpose of this study is to identify whether phase-based instruction using Geometer's Sketchpad helps primary school pupils develop their Van Hiele levels of geometric thinking regarding angles significantly. Eight different pre-sketched activities were designed based on Van Hiele's five phases of learning to guide the students in learning about geometrical angles. Pre and post Van Hiele Achievement Tests were given to both the experimental and control groups before and after the intervention. Inferential statistics such as Mann-Whitney test and Wilcoxon signed-rank test were used in analysing the quantitative data. Results of the pretest indicated no significant difference between both groups of students in their Van Hiele levels of geometric thinking. After the intervention, the findings showed that students in both the experimental and control groups have improved significantly in terms of their Van Hiele levels of geometric thinking. Additionally, results of the Mann-Whitney test revealed that the difference in Van Hiele levels of geometric thinking between students in both groups was significant during posttest. In short, phase-based instruction using Geometer's Sketchpad has helped the students to develop their Van Hiele levels of geometric thinking and provided an insight for the educators to further utilise the software
Analgesic Prescription Patterns and Pain Outcomes in Southeast Asia: Findings From the Analgesic Treatment of Cancer Pain in Southeast Asia Study
No full textPurpose :To identify patterns of analgesic prescription and to explore patient-reported pain intensity, sleep disturbance, and quality of life among cancer patients with pain in Southeast Asia (SEA). Methods: This cross-sectional observational study included 465 adult outpatients prescribed analgesics for cancer pain for 1 month or longer at 22 sites in Indonesia, Malaysia, Philippines, Singapore, Thailand, and Vietnam. Data on analgesic prescription and cancer characteristics were extracted from medical records. Pain intensity, sleep disturbance, and quality of life measures were recorded via questionnaires. Results: Most patients (84.4%) had stage III or IV cancer. A total of 419 patients (90.7%) were prescribed opioids; of these, 42.2% received only weak opioids, whereas 57.8% received at least one strong opioid. The mean worst pain intensity during the past 24 hours was 4.76 (standard deviation [SD], 2.47) on a scale of 0 (no pain) to 10 (worst possible pain); the mean current pain intensity was 4.10 (SD, 2.61). More than half of patients (54.8%) reported sleep disturbance caused by pain in the past 7 days. The majority of patients reported problems with pain/discomfort (82.3%), usual activities (65.8%), mobility (58.2%), and anxiety/depression (56.3%). The median daily dose prescribed in oral morphine equivalents was 30 mg for both morphine and tramadol. Conclusion: Despite unrelieved pain, sleep disturbance, and issues with quality of life, a notable proportion of patients were prescribed only weak opioids, and opioid doses prescribed were generally low. Efforts focused on encouragement of prescriptions with analgesic strength and/or doses proportional to the pain management needs of patients are vital to improve the status of cancer pain management in the region
In vitro and in vivo thermal stress induces proliferation of Blastocystis sp.
No full textBlastocystis sp. is known to be the most commonly found intestinal protozoan parasite in human fecal surveys and has been incriminated to cause diarrhea and abdominal bloating. Binary fission has been widely accepted as the plausible mode of reproduction for this parasite. The present study demonstrates that subjecting the parasites in vitro to higher temperature shows the proliferation of parasite numbers in cultures. Transmission electron microscopy was used to compare the morphology of Blastocystis sp. subtype 3 isolated from a dengue patient having high fever (in vivo thermal stress) and Blastocystis sp. 3 maintained at 41 °C (in vitro thermal stress) and 37 °C (control). Fluorescence stains like acridine orange (AO) and 4′,6′-diamino-2-phenylindole (DAPI) were used to demonstrate the viability and nuclear content of the parasite for both the in vitro and in vivo thermal stress groups of parasites. Blastocystis sp. at 37 °C was found to be mostly vacuolar whereas the in vitro thermal stressed isolates at 41 °C were granular with electron dense material seen to protect the granules within the central body. Parasites of the in vivo thermal stressed group showed similar ultrastructure as the in vitro ones. AO and DAPI staining provided evidence that these granules are viable which develop into progenies of Blastocystis sp. These granular forms were then observed to rupture and release progenies from the mother cells whilst the peripheral cytoplasmic walls were seen to degrade. Upon exposure to high temperature both in vitro and in vivo, Blastocystis sp. in cultures show higher number of granular forms seen to be protected by the electron dense material within the central body possibly acting as a protective mechanism. This is possibly to ensure the ability to survive for the granules to be developed as viable progenies for release into the host system
Effect of lithium iodide on the performance of dye sensitized solar cells (DSSC) using poly(ethylene oxide) (PEO)/poly(vinyl alcohol) (PVA) based gel polymer electrolytes
No full textIn this work, different concentrations of lithium iodide (LiI) have been added to the gel polymer electrolyte (GPE) containing PEO and PVA in equal ratio, tetrabutylammonium iodide (TBAI), ethylene carbonate (EC), dimethyl sulfoxide (DMSO) and iodine crystals (I2). The effect of introducing lithium iodide (LiI) into PEO-PVA blended GPE system having TBAI has been investigated in terms of optical, electrical, thermal and electrochemical characteristics. Fourier transform infrared (FTIR) spectroscopy has been carried out to study the interaction of LiI with the GPEs. The GPE without LiI showed the highest conductivity of 5.50 mS cm−1 at room temperature. With the incorporation of LiI, decrement in conductivity was observed. Dye-sensitized solar cells (DSSCs) with configuration FTO/TiO2/N3-dye/GPE/Pt/FTO have been fabricated and tested under white light of intensity 100 mW cm−2. The DSSC made of GPE with 1.34 wt% LiI exhibited highest efficiency, η of 6.26%