Applied Mechanics and Materials Vol. 835

Abstract: A visible light active nitrogen (N) doped TiO₂ was prepared using commercially available TiO₂ P25. In this study, a simple N doped TiO₂ was prepared by mixing of TiO₂ powder with urea as N precursor under microwave irradiation instead of normal using muffle furnace as heating media. Prepared N doped TiO₂ samples shows active under visible light irradiation due to lower band gaps energy of N doped TiO₂ observed by UV/Vis-DRS. U3-800 was found as optimum N doped where photodegradation rate of RR4 dye under is 1.6 times faster compared with unmodified TiO₂ as well as control TiO₂ under normal 55-W fluorescent lamp. An active photo response under visible light was observed from U3-800 with 80 minutes of time irradiation to complete RR4 color removal, while no photocatalytic degradation was observed from unmodified and control TiO₂. As a result, this study contributed to purification of effluent specifically toxic dyes with complete mineralization under visible light irradiation. For the future work, the modification of TiO2 with nitrogen and metal doping will indirectly increase the efficiency of photodegradation under visible light. In future, the immobilized technique can also be applied for N doped TiO2 to overcome the reusability issue.

Abstract: Industrial wastewater containing toxic pollutants such as heavy metals tends to contaminate the environment once it is release without proper treatment. Heavy metals are toxic to both human and other living organisms. It is necessary to treat industrial wastewater polluted with heavy metals prior to its discharge into the receiving environment. In this study, low cost adsorbent was generated from sugarcane bagasse through incineration. The prepared adsorbent “microwave incinerated sugarcane bagasse ash” (MISCBA) was used in removing copper and zinc from aqueous solution. Parameters of importance such as pH, contact time and adsorbent dosages are studied to investigate their effects on the adsorption of copper and zinc. Maximum adsorption was observed at pH 6.0, contact time of 180 minutes and adsorbent dosage of 10 g/L. Zinc removal follows Langmuir isotherm model with correlation coefficient of 0.9291. Copper adsorption follows both Langmuir and Freundlich isotherm model with correlation coefficient of 0.9181 and 0.9742, respectively. Removal capacities of 38.4 mg/g and 20.4 mg/g were obtained for copper and zinc, respectively. Application of MISCBA as low - cost adsorbent have shown significant outcome in removal of copper and zinc from aqueous solution.

Abstract: In this study, computational fluid dynamics (CFD) simulation was used to predict the performance of photoelectrocatalytic (PEC) reactors with surface reactions. PEC process is a promising and sustainable method that is capable for simultaneous organic degradation and hydrogen production. However, the overall PEC process efficiency is still unsatisfactory and not ready for scale-up application. Preliminary study using CFD model can help to reduce development time, money and effort in experimental work while providing comprehensive analysis and optimum PEC reactor design prior to its real physical fabrication. CFD model integrates irradiance distribution, hydrodynamics, species mass transport and chemical reaction kinetics within the reactor. The performance of PEC reactor for organic degradation depends on reactor configurations and hydrodynamic conditions. Thus, the main aim of this study was to optimize different PEC reactor designs using CFD modelling by varying the reactor configurations and hydrodynamic flow conditions for improved efficiency in degrading the sample organic pollutant of formic acid. The CFD modelling showed higher formic acid degradation efficiency for the simulated convex surface photoreactor than the flat surface photoreactor due to the former possess the ability to concentrate the absorbed light onto the photoanode surface. Besides, the CFD modelling showed that the formic acid degradation rate increased with decreasing inlet fluid flow velocity. This was due to the uniform flow distribution that enables evenly coverage of photoanode surface for subsequent degradation of formic acid in the PEC reactors. Further experimental work is required to validate the CFD simulation to allow better understanding and improvement of the overall efficiency of PEC reactors.

Abstract: This paper deals with mineral wool´s technical parameters evolution in varied time of their life cycle. Hydrophilic mineral wool can be used for a major or a partial substitution of a roof substrate. It can hold rainwater especially for a roof plants when an abundance of this water can be easily drained. Some of the technical parameters do not change in time, but others can differ. This change could be up to the half of their nominal declared values, measured just after the factory production. The aim of this paper is to point out that designing with only factory product data could be at variance with reality and may cause malfunction of green roof, severally when using hydrophilic mineral wool.

Abstract: Ceramic materials are used worldwide due to offer important technical and economic advantages. The ceramic industry, however, has to deal with production losses that are wasted, such as the residue of polishing porcelain tiles. This paper presents the results of laboratory tests performed using different proportions of a lateritic soil and residue of polishing porcelain tile, in order to verify the possibility to use them for highway applications. The main focus of this paper is to propose the optimum ratio of soil and residue based on statistical analysis of the results of unconfined compression tests. Grain size distribution test, X-ray fluoresce analysis and compaction tests were also conducted. An analysis of the data indicates that the addition of residue increases the unconfined compression strength, in comparison to specimens with pure soil. A statistical analysis of the data showed that the best proportion is approximately 92% of soil and 8% of residue.

Abstract: This paper presents a study of thermal comfort of container for a low income flat in Jakarta. This study was conducted since the population of Jakarta is rapidly growing so that the provision of houses for inhabitants especially for low-income communities is necessary. One solution to resolve this issue is vertical housing that concern the sustainability development process; hence, the use of used container may become a suitable choice. However, the drawback of the container is made of aluminum which has high thermal conductivity and can cause poor indoor thermal comfort. This study, therefore, analysed a used container to investigate its indoor thermal comfort. In order to facilitate that objective, a simulation study was conducted. The simulation study consisted of two steps: (1) to simulate the indoor thermal comfort of the container without insulation and (2) to simulate the container after has been added by insulator materials and air gap between the materials. The results showed that by adding insulator materials and air gap as the second layer, the indoor thermal comfort can be improved up to 26%. This result is in the range of the third level of Standard National Indonesia (SNI) thermal comfort version.

Abstract: Over the past decade many studies were conducted to investigate the thermal performance of terraced houses in Malaysia. It was found that this housing typology failed to address the need for thermal comfort and alternatives to the narrow frontage with deep plan have been proposed with simulated good thermal performance. Although this is good progress for new generation of terraced houses, millions of units of terraced houses are still in use and new units with the outdated existing plans continued to get built due to consistently very high demand due to progressive urbanisation and rapid economic developments. Therefore, it is imperative that the thermal comfort issue for existing terraced houses is dealt with and through this paper a comparison between single and double storey terraced houses is made through analysis of indoor environmental monitoring (ambient temperature, relative humidity and air velocity) of two (2) selected case studies in Merlimau, Melaka. Contrary to popular belief, it is found that there is no statistical difference between both sets of indoor temperature and relative humidity between the case studies. This finding is indicative of the consistent and stable temporal temperature highs and lows in a 24 hour cycle despite the difference in indoor volume and distance between the ground floor and the roof cavity. Much of the reason is due to the materiality of the terraced houses construction and unsealed and uninsulated building envelope. Therefore, further research into improving the thermal performance of existing terraced houses of any typology have to be conducted to allow thermal comfort and to reduce reliance on high energy consuming air-conditioning.

Abstract: This study aims to get the openings design of the hybrid systems based on the needs of Air Changes per Hour (ACH) in a vertical housing unit. The research method is quantitative research which the variable is observed from outdoor and indoor wind speed data. Research developed by the experimental research method with CFD simulation to meet the need for air changes.From previous research, case studies obtained ellipse formed by the building mass is the most ideal form to obtain optimum conditions of wind movement.From the result of analysis in this study, requires openings of 0,29 to 1.08 m² with different opening types, to meet the needs of 0.5 ACH under different wind speed. Opening schedule and Hybrid Ventilation system were developed to gain the ideal indoor air condition.

Abstract: This paper presents a study of the process of virtualization or a cultural heritage modeling of Joglo house, an old Javanese house, through observation method. The method consists of three aspects as the following: (1) to observations and measurements, (2) to create a virtual image of the cultural heritage and (3) to integrate the all component of the cultural heritage house, so that the final image is expected to be the replicate of the original house. Additionally, in the process of making traditional Joglo house model, there is another aspect that has been conducted, it was to create harmony between the display of a merger of two and three-dimensional photorealistic models which was made with the help of computer-based applications, namely Computer Aided Design (CAD). As such, by implementing these methods, the reconstruction of cultural heritage of the Joglo house, the Kartasura, can be realized.

Abstract: Generally, volume changes commences almost immediately after the cement and water come in contact during concrete mixing. Humidity of surrounding environment affects the magnitude of shrinkage. Hence, we took it into account by means of Eurocode 2. This paper proposes the evaluation of residual stresses in concrete. To describe the development of residual stresses, magnitude of free shrinkage, degree of its restrain and corresponding value of elastic modulus has to be known. All required quantities was measured apart from degree of restraint. It was tested three types of concrete mixtures. Obtained results show that the free shrinkage value can be significantly reduced by technological way such as the change of concrete composition.