Analysis of controllers in suppressing the structural building vibration

Two degree of freedom (2 DOF) mass spring damper system is used in representing as building structure that dealing with the earthquake vibration. The real analytical input is used to the system that taken at El Centro earthquake that occurred in May 1940 with magnitude of 7.1 Mw. Two types of controller are presented in controlling the vibration which are fuzzy logic (FL) and sliding mode controller (SMC). The paper was aimed to improve the performance of building structure towards vibration based on proposed controllers. Fuzzy logic and sliding mode controller are widely known with robustness character. The mathematical model of two degree of freedom mass spring damper wasis derived to obtain the relationship between mass, spring, damper, force and actuator. Fuzzy logic and sliding mode controllers were implemented to 2 DOF system to suppress the earthquake vibration of two storeys building. Matlab/Simulink was used in designing the system and controllers to present the result of two storeys displacement time response and input control voltage for uncontrolled and controlled system. Then the data of earthquake disturbance was taken based on real seismic occurred at El Centro to make it as the force disturbance input to the building structure system. The controllers proposed would minimize the vibration that used in sample earthquake disturbance data. The simulation result was carried out by using Matlab/Simulink. The simulation result showed sliding mode controller was better controller than fuzzy logic. In specific, by using the controller, earthquake vibration can be reduced

Design and fabrication of FIV apparatus for classroom lecture demonstration

Flow induced vibrations (FIVs) of a cylinder commonly occur where a cylindrical body is exposed to a flow. However, their appearance and behavior are widely diverging depending on flow condition and characteristics of cylinder with its supporting structure, making their prediction quite difficult. Hence, many serious accidents have been caused so far for structures and machines. Most typical and well-known FIVs in this category are the Karman vortex induced vibration (KVIV), the galloping and the torsional flutter. In this work, a very simple and convenient apparatus is designed and made to reproduce these three vibrations. This apparatus will be effective in a classroom lecture of fluid mechanics by demonstrating how easily the FIVs can be induced by a simple apparatus, even though their prediction remains to be important but difficult problems to be solved in practical engineering

A review of cross-cultural analysis on energy behaviour consumption in residential building between Malaysia and Japan

Energy saving behaviour is unique and complex. The role of culture in shaping energy usage patterns in Japanese and Malaysian households is focused in this review study. The Japanese is much better in terms of energy savings behaviour in order to decrease the emission of the country. It will help to sort out energy usage patterns that are rooted in the Japanese culture and thus resistant to rapid changes in technological aspect of buying household appliances. The Japanese daily use of appliances is more effective and efficient than Malaysians who make up one-third of the Japanese population. The impact of occupant behaviour on energy consumption is therefore crucial to be investigated. The findings from this investigation can develop an improved green technology usage for sustainable development in Malaysia

Thermal comfort and occupant adaptive behaviour in university offices with cooling and free running modes

This paper presents results of a small-scale field survey of occupant thermal comfort and adaptive behaviour, conducted in university office buildings in Fukuoka, Japan (August 2014). A comparison was made between offices with cooling (AC) and free running (FR) modes. Indoor environmental conditions were measured, simultaneously with administration of a questionnaire survey. Most Predicted Mean Vote (PMV) values were higher than Thermal Sensation Vote (TSV) values for both cases. This indicates that the PMV model over-predicted actual thermal response. The thermal response in FR offices was found to be more sensitive than in those with AC; additionally, respondents could tolerate a narrower range of variation in indoor operative temperature. Occupants’ adaptive behaviours in AC office were more limited compared to those of respondents with FR. This indicates amenable thermal conditions in A/C-controlled indoor environments, with occupants having no wish to make changes

Time series data measurement on electricity consumption for selected domestic appliances in typical terrace house of Malaysia

This paper describes the pattern of electricity consumption from total and selected domestic appliances at a typical terrace house in Malaysia. The measured appliances can be classified into four groups on the basis of pattern of use which are ‘standby’ (TV), ‘active’ (massage chair, charger of hand phone, laptop and power bank, washing machine, air-conditioners, iron, standing fan, shower heaters, rice cooker, toaster, microwave), ‘cold’ (refrigerator) and ‘cold and hot’ (water dispenser). The major contribution of monthly electricity consumption comes from ‘cold’ appliances that consume 118.8 kWh/month followed by ‘active’ appliances that consume 87.8 kWh/month and ‘cold and hot’ appliance with 52.5 kWh/month. ‘Standby’ appliances shown a small contribution to the total electricity with 0.9 kWh/month. The amount of energy consumed depends on time-of-use, power characteristics of particular appliances as well as occupancy period

Development of robust velocimeter for natural water flow monitoring

The ring-velocimeter coupled with a hot wire/film probe was developed and has been applied to wind and water tunnel experiments in Fluids Engineering Laboratory of Nagaoka University of Technology. In this study, the hot-wire/film probe is replaced by a cantilever attached by a strain gauge to detect the drag acting on the ring. The vortex shedding frequency from the ring is determined from the drag fluctuation by applying the spectrum analysis, and the flow velocity in turn since it is proportional with the vortex shedding frequency. This technique for flow velocity measurement is robust in the sense that it is strong against the noise or decay of the detected signal since the dominant frequency is insensitive to such disturbances, and that the detecting probe is strong against the contaminants or particles/objects carried by the fluid. These advantages, together with its simple and cheap characteristics, make it possible to apply to natural water flow with severe conditions

Numerical study on air-core vortex inside draining tank using different computational modelling approaches

Accurate numerical simulation of liquid draining is important to study the physics fluid flow. However, liquid draining involves multiphase and rotational flows, where numerical simulation is expensive to accurately recreate these flow behaviors. The accuracy of numerical results has been also debatable and it is mainly affected by the computational modeling approaches. Therefore, this study evaluates different computational modelling approaches such as DNS, RANS k-ε, RANS k-ω and LES turbulence models. The results for the draining time and flow visualization of the generation of an air-core are in a good agreement with the available published data. The Direct Numerical Simulation (DNS) seems most reasonably satisfactory for VOF studies relating air-core compared to other different turbulence modeling approaches

Comfort temperature in air conditioned office buildings: case study of Indonesia and Singapore

Air-conditioning system has been a basic feature in many office buildings, especially in tropical climate where buildings are exposed to solar radiation all year round. However, air conditioning is a leading source of energy consumption. Efficient energy consumption is highly desirable for commercial, for-profit entities occupying offices. A field study in two countries; Indonesia and Singapore, has been conducted to investigate office building occupants’ thermal comfort. In 2015, questionnaire survey as well as physical parameter measurements were collected from each country. Analysis shows that occupants of air-conditioned building with window-opening behaviour has higher comfort temperature, compared to cooling mode only. The results of this study could be used to better understand comfort temperature in tropical countries

Large-Eddy Simulation of Wind Flow within a Canyon between Modified Idealized Terraced Houses / Mohamad Nor Hafidz Arif Razali...[et al.]

Adequate wind flow in residential neighbourhood is important for providing a comfortable and healthy environment. It can significantly affect the diffusion of heat; lowering the temperature around it, and the dispersion of traffic-related pollutants between urban surfaces and the atmosphere. In this study, large-eddy simulation, using the Smagorinsky subgrid-scale model, was used to investigate the effect that modifications to a terraced house canyon would have on its wind flow characteristics. The configuration of an idealized terraced house canyon includes a height-to-width ratio h/w = 1/3, and secondary-roughness elements were installed in a staggered, square layout, at 0.5h from the ground. Secondary-roughness elements are treated as modifications to a terraced house building (large-roughness elements). The interaction between an idealized terraced house canyon and secondary-roughness elements has been studied by estimating wind velocity profiles within the terraced house canyon. The velocity profiles have been compared with previous studies to validate the accuracy of the simulation. This study reveals that the modification of the canyon can also affect the wind flow regimes, which might alter the micro climate in the surrounding area, owing to smaller canyon width and sheltering effect from the new obstacle

Investigation of Thermal Comfort at Different Temperature Settings for Cooling in University Building / Mohd Sabri Mustapa ...[et al.]

This paper presented the results of a study conducted on thermal comfort in a postgraduate office of the Malaysia Japan International Institute of Technology (MJIIT, UTM, Kuala Lumpur). The aim of the study was to verify the thermal comfort associated with different air conditioning (AC) thermostat set point temperatures in the cooling (CL) mode. The relevant temperature set points were 20 °C, 24 °C, and 28 °C, as well as the Japanese so-called 'cool biz mode' set point of 28 °C. The thermal sensation vote (TSV) in relation to these CL modes were –0.4, 0.0, 0.8, and –0.1, respectively. These results indicated that at the CL mode of 28 °C, the occupants felt slightly warmer compared to the CL modes of 20 °C, 24 °C, and the cool biz mode. The results of the linear regression analysis indicated the thermal comfort range as 25.3 °C to 26.2 °C, which was close to the range of 25.6 °C to 26.1 °C indicated by employing Griffiths' method