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Effect of raster inclinations and part positions on mechanical properties, surface roughness and manufacturing price of printed parts produced by fused deposition method
No full textAdditive manufacturing (AM) technology has the ability to produce parts or products using data from 3D CAD models based on adding material. Fused deposition modeling (FDM) is among the most popular AM technologies wherein the plastic materials like acrylonitrile-butadiene-styrene filaments get added in the form of semi-molten plastic layers from bottom to top to produce the final product. Besides, the merits of using the FDM process, it faces challenges related to strength, dimensional accuracy, surface finish, and so on. The mechanical, tribological, and surface finish of functional parts is an essential consideration in FDM. In this work, the role of process parameters such as the part positions and raster inclinations involved in the manufacturing of parts by FDM has been evaluated experimentally to obtain the desired properties for reducing production time, the quantity of supporting material, and overall cost including maintenance costs. The study revealed that part position is a more significant parameter than the raster inclinations on the surface roughness and mechanical properties of the FDM parts. It also concludes with the proper values of part positions and raster inclinations for achieving optimal mechanical properties, roughness, and manufacturing costs to withstand operating loading conditions
The extraction of dragon fruit pericarp as colouring agent for painting
No full textDragonfruit pigment is the new colouring agent of this era and proves to be rich in its natural magenta pigment. The strong pigment and high stability has inspired the researcher to come up with a specific test on the credibility of the colours and as an alternative colouring agent to be used on paintings and textiles. The results from this scientific experiment on the pigment proved that it had the strength and stability needed. Although it has not been processed but the role of it being a new colouring agent is as good as synthetic dye that has been established in the market. The specific experiment on artistic test has proved that this pigment also acts as a versatile colouring agent. This could be seen on the compatibility on this pigment and its reaction towards other medias such as canvas, fabric and paper as test on colour stability. As the new colouring agent, it is hoped that the dragonfruit pigment will be given serious consideration as this natural source should be exploited and the uses variated for future use
Using computational fluid dynamics to predict the erosion rates on the cyclones wall for coal boiler plant
No full textIn the industrial coal boiler, cyclone is used to separate the silica sands (as fluidizing medium) from the furnace combution gas. A gas-solid separation system with turbulent swirling flow that occurs in the cyclone will cause erosion on the cyclone wall. The erosion will cause a decrease in the cyclone performance and increase the maintenance cost. CFD simulation was conducted to predict this erosion using industrial cyclone in the coal boiler industry on its actual dimensions. The dimensions were 5120 mm in diameter and 13970 mm in height. It was performed using the Reynolds Stress Model (RSM) for turbulence flow in the gas phase and the Oka erosion model. The erosion rate on the cyclone wall was investigated at various gas inlet velocity and solid rate. The inlet velocities ranged from 6 to 8 m/s and the solid rates ranged from 30 to 40 kg/s with silica sands as solid particles (0.075 and 1.5 mm in diameter). At the selected local area, the results showed that the higher gas inlet velocity for the same solid rate would increase the erosion rate (about 25%). However, the higher solid rate for the same velocity will also increase the erosion rate on the cyclone wall (about 18%). These results indicate that cyclone wall errosion are significantly affected by inlet gas velocity
Kepentingan pelaburan langsung luar negara dalam model china dan impaknya terhadap kuasa lunak China
No full textPengalaman pembangunan ekonomi China pasca pelaksanaan reformasi dan liberalisasi ekonomi pada Disember 1978 membawa kepada pertumbuhan ekonomi yang menakjubkan dalam sejarah pembangunan China. Antara penekanan yang diberikan dalam reformasi dan liberalisasi ekonomi tersebut adalah keterbukaan industri dan perkembangan eksport dengan memberi ruang kepada pasaran, namun masih dalam kawalan ketat oleh negara. Sejak itu juga mula muncul istilah Model China dalam menjelaskan proses pembangunan ekonominya. Kebangkitan China sebagai hegemoni ekonomi baharu dunia dapat dilihat melalui strategi pelaburan langsung luar negara (ODI) yang mengintegrasikan China ke dalam ekonomi antarabangsa. Objektif kajian ini adalah untuk menganalisis Model China sebagai mekanisme yang memacu pertumbuhan ekonomi serta membincangkan kepentingan ODI dalam Model China berdasarkan perkembangan penulisan kajian-kajian terdahulu. Kajian dijalankan dengan mengaplikasikan kaedah kualitatif. Berdasarkan analisis yang dilakukan, hasil kajian mendapati Model China merupakan strategi penting dalam pembangunan ekonomi China. Manakala ODI pula bukan sahaja salah satu faktor dominan dalam perkembangan Model China tetapi juga sebagai instrumen penting dalam strategi kuasa lunak China. Kesimpulannya, kajian ini mengetengahkan kepentingan Model China yang membawa keajaiban dalam pembangunan ekonomi China dan menyumbang kepada korpus ilmu tentang peri pentingnya pengalaman pembangunan ekonomi China yang boleh dijadikan panduan kepada negara-negara membangun yang lain untuk merangka strategi pembangunan ekonomi masing-masing
Ab Iiitio study of optoelectronic properties of VSb2 compound
No full textThe optoelectronic properties of VSb2compound were studied using the Full Potential Linearized Augmented Plane Wave (FP-LAPW) method, in accordance with the Density Functional Theory (DFT). Thus, this studycalculated the total (TDOS) and partial (PDOS) density ofstates by the Engel-Vosko Generalized Gradient Approximation(EV-GGA) implemented in the Wien2k code. From thecalculations,the material possesses a metallic character. Furthermore, thecalculation involvesthe energy range between 0 eV and 14 eV, the optical spectra including the real and imaginary part of the dielectric function, the refractive index, the extinction coefficient, the optical conductivity, the absorption coefficient, the reflectivity and the loss function, considering both intra-and inter-band transitions. The optoelectronic properties study of VSb2intermetallic compound is important because this material is likely to be used as a diffusion barrier, as an electrode or in photovoltaic cells after doping or association with other materials.The results of the electronic properties show the main contribution of the V-3d states in the DOS. Similarly, the total density of states at Fermi energy N (EF) is6.4 States/eV and an electron specific heat coefficient ? is15.1 mJ.mol-1.K-2.As for the optical properties,the VSb2is found to has a strong absorbance in the ultraviolet region and high reflectance in theinfrared domain.This work is original because, according to the literature, even if this material has already been synthesized, no experimental or theoretical calculation of theoptical properties has been made until now
COVID-19 and mental health: Our reactions to its actions
No full textThe genetic epidemiology suggests that coronavirus disease 2019 (COVID-19) is most likely transmitted to the human population in November or December 2019,originating from Wuhan and spread entirely by human-to-human transmission. The period of the Chinese New Year holidays is thought to be one of the key periodswhere a substantial transmission took place within Wuhan. Moreover, the movement of people from Wuhan resulted in massive spread nationally and internationally when people traveled during the holiday
Examining the quality of english test items using psychometric and linguistic characteristics among grade six pupils
No full textPurpose - This study examined the quality of English test items
using psychometric and linguistic characteristics among Grade Six
pupils.
Method - Contrary to the conventional approach of relying only
on statistics when investigating item quality, this study adopted a
mixed-method approach by employing psychometric analysis and
cognitive interviews. The former was conducted on 30 Grade Six
pupils, with each item representing a different construct commonly
found in English test papers. Qualitative input was obtained
through cognitive interviews with five Grade Six pupils and expert
judgements from three teachers.
Findings - None of the items were found to be too easy or difficult,
and all items had positive discrimination indices. The item on idioms was most ideal in terms of difficulty and discrimination.
Difficult items were found to be vocabulary-based. Surprisingly,
the higher-order-thinking subjective items proved to be excellent
in difficulty, although improvements could be made on their ability
to discriminate. The qualitative expert judgements agreed with the
quantitative psychometric analysis. Certain results from the item
analysis, however, contradicted past findings that items with the
ideal item difficulty value between 0.4 and 0.6 would have equally
ideal item discrimination index.
Significance -The findings of the study can serve as a reminder
on the significance of using Classical Test Theory, a non-complex
psychometric approach in assisting classroom teacher practitioners
during the meticulous process of test design and ensuring test item
quality
Revisiting the Dusunic boat lutes of Sabah: Disappearing musical traditions
No full textThe Kadazan Dusun sundatang from Tambunan, the Rungus sundatang, and the Lotud gagayan are three kinds of boat lutes from Sabah. Each is carved from a single log of jackfruit wood, but vary structurally. Resembling somewhat Philippine boat lutes, they differ from the sape-types of Sarawak and Kalimantan. They are played solo in non-ritual contexts. The gagayan, however, was played in pairs (batangkung) and the Tambunan sundatang was sometimes accompanied by a hand-held gong when accompanying the slow, sedate magarang sundatang dance. Today, there are very few musicians playing the unique Tambunan sundatang, while the Lotud gagayan has recently declined with the demise of older performers. The Rungus sundatang is still extant and continues to be performed in many longhouses. This paper discusses these three types of Dusunic boat lutes, their structures, performance practices and music, and suggests a possible origin for these kinds of instruments found in northern Borneo