19672 research outputs found
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A few-picosecond and high-peak-power passively mode-locked erbium-doped fibre laser based on zinc oxide polyvinyl alcohol film saturable absorber
No full textThis paper demonstrates a few-picosecond and high-peak-power mode-locked fiber laser, using an erbium-doped fiber as a gain medium and zinc oxide (ZnO) element as a new passively saturable absorber (SA). The ZnO element was synthesized using a seeding solution and amended with a polyvinyl alcohol to form a film. The ZnO has been identified as an ideal SA due to its high nonlinear optical response, high sustainability to damage threshold, and fast recovery time. Self-started mode-locked laser pulses have been generated at a relatively low pump power of 42 mW with a fundamental repetition rate and pulse duration of 3.26 MHz and 2.60 ps, respectively. The proposed laser operates at 1599.5 nm with a 3 dB spectral bandwidth of 1.12 nm. A maximum output power, pulse energy, and peak power of about 6.91 mW, 2.12 nJ, and 0.82 kW, respectively, are obtained at a maximum pump power of 159 mW. From these findings, we confirm that the proposed laser can be viewed as a promising light source in the emerging optical communication system
Residents' Satisfaction Towards the Indoor Environmental Quality of Re-engineered Affordable Housing Scheme in Malaysia
No full textMalaysia is currently focusing on providing affordable housing all over the country, as part of the plan to tackle the problem of the rising costs of house ownership due to reasons such as the economic crisis and land limitations. However, a limited number of methodical studies have been conducted on residents' feedback on the indoor environment of affordable housing. Indoor Environmental Quality (IEQ) is an important aspect of occupants' wellbeing, as it affects their health and productivity. Therefore, evaluating residents' feedback on IEQ is an important step in gauging building performance and conditions. In addition, the health and productivity of residents needs to be evaluated in order to identify the effect of IEQ on them. A questionnaire survey was used to achieve the study objectives and to gain access to the respondents' views and feedback. The pilot questionnaire study was conducted at two housing apartments in Kuala Lumpur, Malaysia, and the data collected were evaluated and analyzed using SPSS software. The outcome of this pilot study is significant, as it shows the residents' dissatisfaction level towards IEQ factors such as noise, glare and privacy, and other aspects of IEQ that are important, such as ventilation. Additionally, it has been found that the IEQ of the residents does affect their health and productivity. It is anticipated that the outcome of this study will serve as an indicator of building performance improvements needed to achieve a better indoor environment quality for affordable housing in Malaysia
A design method for developing a high misalignment tolerant wireless charging system for electric vehicles
No full textThis paper proposes a design procedure which optimizes the electrical parameters involved in the Inductively Coupled Power Transfer (ICPT) system and correlates them with geometrical dimensions of the charging coils involved for charging of electric vehicles. The Inductively Coupled Power Transfer (ICPT) system makes it possible to charge the Electric Vehicles (EVs) wirelessly at some distance to avoid safety issues and to provide convenience to the users. The ICPT system has potential applications in the field of medical sciences, office appliances, industrial loading machines, and battery charging applications. Although the ICPT system has been successful for the charging of the electric vehicles, but it retains some challenges, prominently limitation of misalignment tolerance and low efficiency of the overall circuit. The methodology presented in this paper helps in choosing appropriate dimension of the coils and electrical parameters to cope with the issue of misalignment tolerance. A program based on the mathematical model has been developed in Matlab software to determine optimal values of overall ICPT system circuit parameters and the geometrical dimensions of coils. The experiments of the ICPT system have been carried out with developed optimal coil design for 1 kW power transfer at various air gaps. The misalignment tolerance of the ICPT system has been recorded and presented in the paper. The proposed optimal design achieves maximum efficiency of 90.5% at perfect alignment, however, it maintains the efficiency of 72% at 35–40% misalignment between the coils. The misalignment test results support the design of coils for EV charging application
Polysulfone mixed-matrix membrane incorporating talc clay particles for gas separation
No full textMixed-matrix membranes (MMMs) have showed advantages in membrane-based gas separation in recent years. However, there is still intensive demand for the development of membranes incorporated by proper fillers for further enhancement of gas separation performance. In this study, mixed-matrix membrane (MMMs) has been synthesized by incorporating of different content of talc into polysulfone (PSf) polymer specifically upon the separation of carbon dioxide from methane. The influence of filler content on the gas separation performance of the fabricated membranes was studied. The prepared MMMs were analyzed by thermal gravimetric analysis (TGA), X-ray diffraction (XRD), derivative thermo-gravimetric (DTG), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and pure gas permeation testing. XRD analysis suggested that talc layers crystalline structure was changed slightly due to blending and just limited PSf chain intercalation occurred. The results showed that the rate of gas permeation increased with increasing talc content while the selectivity declined at 0.5 wt% due to filler agglomeration as confirmed by FESEM. The best results were obtained at 0.1 wt% talc compared to neat PSf with superior gas separation behavior
Effect of replacing fishmeal with palm kernel meal supplemented with crude attractants on growth performance of Macrobrachium rosenbergii
No full textA 60-day feeding trial was conducted to study the effect of partial replacement of fishmeal with palm kernel meal (PKM) on growth performance and oxidative stress of Malaysian prawn, Macrobrachium rosenbergii. A closed aquaculture system with 21 fibreglass tanks with the capacity of 150 liter was used for the experiment. Five iso-energetic (19 KJ/g DM gross energy) test diets were formulated by replacing 0, 10, 20, 30 and 40% of fishmeal with PKM and labelled as PKM0, PKM10, PKM20, PKM30 and PKM40, respectively. Another two diets were prepared by the supplementation of 2% shrimp meal and 2% squid meal in PKM30 (PKM30+) and PKM40 (PKM40+) diets, respectively. Triplicate groups of 30 post-larvae (0.041±0.001 g) were stocked in previously prepared tanks and fed the test diets at the rate of 10-15% of their body weight, twice a day. The results showed that there were no significant differences (p > 0.05) in weight gain and specific growth rate of prawn fed PKM0, PKM10, PKM20 and PKM30 diets. However, the growth parameters were significantly decreased in prawn fed PKM40 diet. Supplementation of crude attractants recovered the depleted growth performances in PKM30+ and PKM40+ groups. The feed utilization parameters also followed the similar trends. The superoxide dismutase activity was similar in all the dietary treatments except in PKM30. It is concluded that 30% fishmeal can be replaced with PKM in the diets of prawn without any detrimental effects on growth performance and feed utilization. Supplementation of small amount of crude attractants such as squid meal and shrimp meal could replace 40% or more fishmeal from the diet of Malaysian prawn
Performance of natural dyes as sensitizer in dye-sensitized solar cells employing LiBOB-based liquid electrolyte
No full textDye-sensitized solar cells (DSSCs) were prepared with natural dyes as sensitizer and liquid electrolyte based on LiBOB polymer. DSSCs with chlorophyll dyes exhibited a better performance in LiBOB-based liquid electrolyte without LiI while anthocyanin and mangosteen dyes achieved higher performance in LiBOB-based liquid electrolyte with addition of LiI. Overall efficiency and fill factor of DSSCs varied from 0.09 to 0.64% and 27 to 66%, respectively. LiBOB-based liquid electrolyte is also suitable in DSSC utilizing N3 dye as sensitizer with significantly better performance than natural dyes. The better performance of natural dye DSSC with LiI inclusion in the electrolyte is attributed to the high conductivity of the electrolyte as a result of more ion-pairs formation
Improving accuracy of conceptual cost estimation using MRA and ANFIS in Indonesian building projects
No full textPurpose: The purpose of this paper is to develop a conceptual cost estimation (CCE) model for building project by using a pragmatic approach, which is a mix of tools drawn from multiple regression analysis (MRA) and adaptive neuro-fuzzy inference system (ANFIS), to improve the accuracy of cost estimation at an early stage. Design/methodology/approach: This paper presents a set of MRA and integrating MRA with ANFIS or MRANFIS. A simultaneous regression analysis was developed to determine the main cost factors from 12 variables as input variables in the ANFIS model. Cost data from 78 projects of state building in West Sumatra, Indonesia were used to indicate the advantages of the proposed model. Findings: The result shows that the proposed model, MRANFIS, has successfully improved the mean absolute percent error (MAPE) by 2.8 percent from MRA of 10.7–7.9 percent for closeness of fit to the model data and by 3.1 percent from MRA of 9.8–6.7 percent for prediction performance to the new data. Research limitations/implications: Because the significant variables are different for each building type, the model may be not appropriate for other buildings depending on the characteristics of building. The models can be used and analyzed based on the own historical project data for each case so that the model can be applied. Originality/value: The study thus provides better accuracy of CCE at an early stage for state building projects in West Sumatra, Indonesia by using the integrated model of MRA and ANFIS
Q-switched Erbium Doped Fiber Laser Incorporating Antimony (III) Telluride in Polyvinyl Alcohol as Saturable Absorber
No full textIn this paper, we demonstrated a Q-switched erbium doped fiber laser (EDFL) incorporating Antimony (III) Telluride (Sb 2 Te 3 ) in polyvinyl alchohol (PVA) as passive saturable absorber. The saturable absorber was fabricated by dissolving Antimony (III) Telluride powder into PVA solution and dry in the ambient temperature for 48 hours. Then, 1 mm 2 x 1 mm 2 Sb 2 Te 3 -PVA film based saturable absorber were sandwiched in between FC/PC ferrule for Q-switched laser generation. The stable and self-started Q-switched laser operates at center wavelength 1560 nm with 3 dB bandwidth of 0.23 nm. The laser operates at pump power of 29.3 mW until 84.9 mW with repetition rate of 20.99 kHz to 89.29 kHz and pulse width of 13.95 µs to 5.10 µs. At maximum pump power, the laser able to achieve pulse energy of 62.72 nJ and high signal to noise ratio of 71.4
Factors influencing students’ satisfaction in using wireless internet in higher education
No full textPurpose – In this age of exponential knowledge growth, where wireless internet is playing a dominant role, the concerned authorities of higher education have to ensure that this tool remains within the reach of the students. However, there has been as yet little research indicating its success in China. This paper aims to examine factors that influence students’ satisfaction (SAT) in using wireless internet in higher education for the purpose of learning. The second aim of this study is to identify if gender has a moderating effect on students’ SAT in using wireless internet in higher education. Design/methodology/approach – Data from a total of 283 students from five colleges of a comprehensive public university in China (Foreign Language Studies, Business, Education, Biology and Chemistry, and Mathematics and Engineering) were collected for this study. The reliability and validity of the measurement scale were established through a Rasch model using Winsteps version 3.94. The technology satisfaction model (TSM) was validated applying structural equation modelling (SEM) using AMOS to test the causal relationships among the constructs. Findings – The results of this study revealed that students’ SAT was directly influenced by perceived usefulness (PU) and ease of use of wireless internet. Besides, students’ perceived ease of use (PEU) and usefulness were directly affected by their computer self-efficacy. On the other hand, students’ computer selfefficacy had an indirect effect on their SAT mediated by ease of use and perceived usefulness, respectively. The findings also discovered that gender did exert effect as a moderating variable towards students’ SAT in using wireless internet in higher education. Practical implications – The TSM was shown to be a useful model to measure students’ SAT in using wireless internet in a different culture
Embedded Librarianship in Research in Nigerian Universities: Practices and Sources of Practice Knowledge
No full textAcademic librarians have begun to take the reference desk services outside their library premises to raise a new level of importance within and beyond their communities. Through embedded librarianship (EL), librarians move from a supporting role into partnership with their clientele, enabling librarians to develop stronger connections and relationship with those they serve. Academic librarians in Nigerian universities are given full faculty status and they have the responsibilities for teaching, research, and academic services, enabling a more natural climate for collaboration. EL in the research context is still an emerging model, the pathways to engagement and the criteria for success in Nigerian universities have not yet fully defined. Realizing this, the objective of this paper is to explore how academic librarians in Nigeria universities practice EL in research. This is a qualitative exploratory study, purposively sampled 12 academic librarians who are (a) embedded with schools or academic departments; and (b) directly involved in collaboration with faculties or partners in relation to research. Semi-structured interview was used for the data collection. Six themes that emerged from the embedding practices are (a) doing research and publishing papers; (b) being editor of a national journal/reviewing manuscripts of publication; (c) managing the life cycle of data; (d) disseminating research output; (e) providing scholarly publication service and bibliometrics analysis; and (f) conducting research method course. These embedded roles offer librarians means to increase their value in their organizations, their communities, and society as a whole. However, with regards to the sources of knowledge needed to foster learning and information sharing in EL, the librarians play an integral role as research partners because they have traditionally excelled in literature search, and very familiar with database content and its search language and features. This paper covers only the role of embedded librarians in research in three selected Nigerian Universities. Obviously, there is demand for further research to be conducted in other context. Further study need to be carried out on the relevance of EL to the library and stakeholders