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Thermal comfort of indoor open spaces at university library in Malaysia
Get PDFThe issues of improving thermal comfort inside the building have become a global point of research interest attributed to the realization that people spend more than 90% of their time in the indoor environment. This study investigated the thermal comfort temperature range for indoor open spaces in second level of the Universiti Tun Hussein Onn Malaysia (UTHM) library. The study conducted through subjective measurement (thermal sensation questionnaire) and physical measurement (air temperature, relative humidity, air velocity, mean radiant temperature measurement). A total of 120 occupants completed the thermal sensation questionnaire of indoor open spaces for morning and afternoon sessions for six days. Physical measurements data were also collected at eight measurement sampling point across the indoor open space for six days. The linear regression analysis for air temperature with thermal sensation vote (TSV) and predicted mean vote (PMV) for both morning session and afternoon session shows a good fit of the regression model on the observed data. It shows 70% of the variation in the output variable of TSV and PMV can be explained by the input variables of air temperature. The thermal comfort temperature ranges for TSV of -0.5 to +0.5 were within the range of 24.17 ∸C to 25.01∸C for morning session and 23.63 ∸C to 24.20 ∸C for the afternoon air temperature. In addition, the thermal comfort temperature ranges for PMV of -0.5 to +0.5 were 24.03 ∸C to 25.15 ∸C for morning session and 23.70 ∸C to 24.47 ºC for the afternoon. By using linear regression equation, the relation between air temperature, PMV and TSV were obtained
Tribological behavior of organic anti-wear and friction reducing additive of ZDDP under sliding condition: synergism and antagonism effect
Get PDFThe effect of eichhornia crassipes carbon nanotubes (EC-CNTs) as additives in both base mineral oil (MOO) and vegetable rapeseed oil (ROO) alone and also together with ZDDP additive under sliding condition was studied. The investigation shows that both on individual and in combine state enhanced tribological properties. The coefficient of friction reduction was 40 % and 37.5 % for EC-CNT inclusion against ROO and MOO respectively under 80 N. The study revealed that enough tribofilm were generated thereby separating the two surfaces leading to low COF. In the case of wear effect, combination of the two additives gives substantial reduction of 65.5 % and 70.2 % against MOO and ROO respectively. The study shows that more reduction was obtained with RO + EC-CNT + ZDDP than the other. The use of two additives in combine lubrication shows synergistic effect, however, observed antagonistic effect if MO + EC-CNT + ZDDP is used for long period of time. The study further revealed that EC-CNT does more of anti-wear service while ZDDP improves friction reducing effect as well as anti-wear
Fabrication of light-weighted acoustic absorbers made of natural fiber composites via additive manufacturing
Get PDFSynthetic fiber is still considered the best sound absorptive material. However, due to the health concern of synthetic fiber usage, researchers are trying to find another viable alternative. A microperforated panel (MPP) is a promising alternative that relies on the concept of a Helmholtz resonator for sound absorption. MPP possessed excellent acoustic resistance and a considerable range of absorption bandwidth. In this paper, MPP made of natural fiber composite was fabricated and its acoustic absorption was measured using a two-microphone impedance tube method as per ISO 10534-2 standard. Later, the tensile strength of the fabricated acoustic absorbers was measured using an Instron Universal Testing Machine as per ASTM D638. The idea of employing additive manufacturing, better known as the 3D printing technique, is proposed to produce lightweight MPP. The 3D printing technique provides design freedom and is less tedious in creating complex and light structures. The 3D printing technique has various important parameters, and infill density is one of the parameters. It was found that the reduction of infill density leads to a decrease of the MPP’s mass and thus, slightly affects the resonance frequency of the MPP, still within the mid-frequency spectrum. It was also noted that the increment of air gap thickness leads to the shifting of MPP’s resonance frequency to a lower frequency range. The tensile strength of the 3D printed samples decreases with a decrease in infill density. A sample with an infill density of 100% has the highest tensile strength of 22 MPa, and a sample with an infill density of 20% has the lowest tensile strength of 12 MPa
Effects of lime on the compaction characteristics of lateritic soil in UTM, Johor
No full textLime has been investigated as a ground improvement material for soils, particularly for road construction, as an alternative to soil cement stabilisation. However, the effect of lime on lateritic soil compaction characteristics is not completely defined. In this article, soil samples from Universiti Teknologi Malaysia (UTM), Skudai, Johor were subjected to a variety of engineering tests, including specific gravity, sieve analysis, Atterberg's limit, and compaction. According to the results of Atterberg's Limit, lateritic soil has a plasticity index (PI), a plastic limit (PL), and a liquid limit (LL) of 19, 46, and 65, respectively. The obtained specific gravity value is 2.79. Compaction tests were conducted on untreated and lime-treated soils with lime additions of 3%, 5%, 7%, and 9%, respectively, using an automatic compactor. The OMC and MDD values for untreated laterite are 28% and 1.46 g/cm3, respectively. However, as the lime content increases, the OMC increases slightly while the MDD decreases. The dry density of lime-laterite soil decreases from 1.47 to 1.38 g/cm3, but the moisture content increases slightly from 27% to 31%. The MDD of soil treated with 5% lime is lower than that of lateritic soil in its natural state
Recent developments in machine learning and flyrock prediction
No full textThe blasting techniques are employed in mining and underground works to loosen the rock mass and ease the excavation. The blasting practices are economical and swifter in terms of their engineering application, however, they are of major environmental and safety concerns. The major issues related to blasting are flyrock, air over pressure, and ground vibrations etc. The rock fragments of rockmass are thrown outward after blasting, which can be threat to workers and machineries involved in the work, and sometimes nearby human settlements can be its victim. Therefore, an accurate prediction of the flyrock distance is the needed by mining practitioners. Earlier, experts have developed several empirical methods based on certain known parameters to assess flyrock distance. However, with time they become irrelevant and were easily replaced with advanced machine learning algorithm. The present study reviews some of these latest publications (2019–2021) examining flyrocks through artificial intelligent technique. The study incorporates types of machine learning models employed, input parameters used and number of datasets supporting the models. The input parameters were further classified according to rock-mass properties, blast design at site, and explosives responsible for blasting. Moreover, to compare the reliability of the model coefficient of correlation of the testing data of the all the documented model were evaluated. Rock density, rock mass rating and Shmidt hammer rebound number (SHRN) were found to be uncertain parameters. Artificial Neural Network (ANN) and other hybrid models for prediction of flyrock were compared
Chemical properties of modified bitumen incorporating coconut char
No full textAgriculture waste have many advantages such as high specific strength and modulus, low density, renewable nature, biodegradability and absence of health hazards. This advantage is good for construction industry because it can improve the properties of the composites. The coconut fruits contain 40% coconut husk, 30% fiber and 30% dust, consisted of flesh, shell and fiber and chemical composition such as cellulose, lignin, charcoal, acid and potassium. The advantages of coconut shell are strong, rigid and lightweight material, very economical as large amounts are available as agricultural waste material and environmentally friendly. This paper presents the performance of modified binder incorporating coconut char in terms of chemical properties. Fourier Transform Infrared Test (FTIR), Particle Size Analyzer Test (LPSA) and Elemental Analyzer Test (EA) were used to analyze the chemical properties on modified binder. Based on the findings, the increased content of char affects the performance of bitumen significantly, as the bitumen maintains stability and homogenous state even though placed in high temperature condition. The testing result value of FTIR and LPSA are increased with the increased content of coconut char. Based on the results, the modified mixture has the higher chemical components and porosity compared to original bitumen and coconut shell because of the modification
Effects of moisture damage sensitivity of asphalt mixtures incorporating treated plastic as additive
No full textThe issue of moisture damage due to water intrusion in conventional road pavement is crucial due to increasing traffic load and volume, especially in the dry process. Poor workability occurs between the aggregate and binder interaction, increasing air voids in the asphalt mixture. Consequently, reduce the strength of the asphalt mixture. Hence, the additive material is one possible approach to reduce the issue. The use of treated plastic (Low-density Polyethylene) (TP) has a high potential to improve the interaction of aggregate and binder during the mixing process to against moisture damage. Further investigation on the effect of different ratios of TP content (0, 2.5, 5.0, 0.75, and 1.0% by weight of total aggregate) in asphalt mixture was studied. Mechanical performances on moisture damage of the optimum TP content in asphalt mixture were focused and evaluated with retained stability and tensile strength ratio tests. The finding revealed that 0.75% of TP content increased the resistance of moisture damage in asphalt mixtures compared to the conventional mixture
Nursing students’ perception of caring: a literature review
Get PDFAim: Exploring nursing students’ perceptions regarding caring is essential, especially for nursing educators, in order to provide information for planning a curriculum in nursing education. The aim of this literature review was to synthesize the literature regarding nursing students’ perceptions of caring based on the available primary research. Design: A literature review. Methods: Six electronic databases (Web of Science, PubMed, Science Direct, SCOPUS, Wiley Online Library, and SAGE) were searched. Articles were selected according to PRISMA guidelines. A thematic synthesis framework was applied in this review. Results: Thirteen primary studies were included and synthesized, and seven analytical themes emerged. The analytical themes were: caring as presence, caring as support, caring as professionalism, caring as communication, caring as establishing relationships, and patient well-being as a positive outcome of caring. Conclusion: Caring was perceived variously in this review, and consisted of physical aspects, emotional aspects, and professional aspects, together with obedience to the nursing codes of ethics. Finally, it was felt that being caring to patients should not mean that nurses neglect their own self-care
Sustainable use of plastic waste on laterite soil as stabilizer
No full textPlastic has been widely used in many fields due to its lightweight, strength, durability, and capable of being moulded in any form. However, plastic pollution has become one of the major threats to the world since plastic waste is non-biodegradable and composed of higher toxic pollutants that may harm the environment significantly. Therefore, recycle and reuse of plastic waste can be one effective way to reduce the risk of plastic pollution. With the rapid growth of cities, one of the main constraints in the construction industry is the availability of land with allowable soil settlement and sufficient bearing capacity. Therefore, the engineers need to find alternative solutions to make use of the land area even though with weak soil properties. One of the effective and low-cost ways is to reinforce the soil strength using plastic waste. This research was conducted to study the effect of using plastic waste as soil reinforcement in laterite soil. Variations in compaction characteristics and unconfined compressive strength of laterite soil for different plastic waste content and dimension were investigated. The results obtained were compared with untreated laterite soil. The optimum percentage and dimension of plastic waste needed to increase the soil strength were obtained from the results. The soil strength reinforced with plastic waste can be reduced as the percentage and dimension of plastic waste exceed certain proportions and sizes
Physiochemical characterization of lateritic bauxite mining soil
Get PDFPhysiochemical characteristics play a significant role in evaluating the engineering behaviour of soil material and its suitability for foundation. Investigation upon the physical and chemical characteristics of lateritic bauxite soils were done on samples collected from three ex-mining bauxite sites (Bukit Goh, Semambu and Indera Mahkota) in Kuantan District, Pahang, Malaysia. The presence of chemical element was evaluated based on the elemental mineral composition content identified through X-Ray Fluorescence (XRF). The results revealed that Semambu lateritic bauxite soil has the highest content of alumina (Al2O3), 25.54%. The alumina content enrichment is one of the effects from the laterization of bauxite process. In addition, the physical testing included are moisture content, specific gravity and Atterberg Limit. Further investigation on the physical properties of the soil has found that Semambu has the highest MC, 33.27%, but at the same time PI is less than 12%. This is as a key indicator that lateritic bauxite is prone to surface erosion and unsuitable for construction purposes in its natural condition. The risk of the surface erosion and settlement of the ground causes it requires stabilizer that can rapid the curing time. Additionally, the high moisture content is likely to have higher chance to experience liquefaction and causes foundation problem to future infrastructures that may be built in the studied area