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Seismic fragility of concrete building in Malaysia considering the effects of inadequate lap splice length
Get PDFThe tremors due to Sumatra earthquake have been reported recently with low to moderate seismic activity level, which have been causing fear to people who are in Peninsula Malaysia. Those, that the new structure should be built or partially built with retrofitting of the existing structure, are the major questions to design globe, which lead essential seismic hazard assessment is necessary to ground motion scenarios due to potential earthquakes. A gap in the previous studies was identified that the inadequate lap splice length in column may give higher probability of exceedance in the seismic design. Accordingly, the seismic fragility curve development is useful in contributing further insight to the continuing evolution of low ductile reinforced concrete frame subjected to far field ground motions with studying the effects of inadequate lap splice length. Three models such as three-, six- and nine- storeys, in low ductile bare reinforced concrete frames developed through ETABS, were included in this study. In order to develop the adequate lap splice lengths to RC frame in ETABS, the P-M2-M3 hinges were assigned to all joints in column with “controlled” dynamic lap splice lengths under column behaviour while all hinges in beam and columns were developed with the behaviours based on American Society of Civil Engineers, ASCE 41-13, standard of seismic evaluation and retrofit of existing buildings. Subsequently, all RC frame models were subjected to analyses such as static pushover, push over with first mode and push over with dynamic mode, the observation of the plastic hinges formation in terms of the damage levels of IO, LS and CP were predicted, and finally, the maximum storey drifts of each damage level were projected to determine as capacity of RC frame in the development of fragility assessment. In addition, the performance of all models was studied by a series of Incremental Dynamic Collapse Analysis (IDA) by means of incremental of 0.05g until 0.50g, which were subjected to 15 far-field ground motions. Based on maximum storey drifts in each analysis from IDA, the median, standard deviation and standard error corresponding to Peak Ground Acceleration (PGA) value were attained as demand of the fragility assessment. Finally, according to the predicted capacity and demand, the fragility curves were presented to the frames of 3-storey, 6-storey and 9-storey with column behaviour consisted of controlling inadequate development or splicing subjected to far-field earthquake excitations. By providing adequate lap splice lengths in columns, the push over analysis showed that there were no damages in columns near foundation while the columns near foundation showed the damage levels of IO, LS and CP when they do have inadequate lap splice lengths. In capacity assessment by push over analysis, maximum storey drifts in all cases were increased by providing adequate lap splice lengths, which this trend brought to be stated that the columns were improved in strength to bear horizontal loads against horizontal displacement. Also, based on the observation of plastic hinge formations at all levels, the damage levels were postponed by providing adequate lap splice lengths to columns and this is a very convenient representation to avoid column failure and postpone the damaged states. Based on the predicted maximum storey drifts from IDA, the storey drifts were lower in all cases due to providing adequate lap splice lengths to columns, which this study brought that the parameter of inadequate lap splice length will be super imposition parameter in controlling the drifts and avoiding structural damages. Developed fragility curves can be a statistical tool in representing the probability of exceeding against PGA and for estimating a specific damage measure in design practice
Growth response of different oil palm seedling parentage towards chemical fertilizer treatment
Get PDFOil palm (Elaeis guineensis) requires a sufficient amount of chemical fertilizer to sustain their growth and development. To date, many oil palm varieties are available commercially. These varieties may experience insufficient or excessive fertilization as their specific nitrogen and potassium requirements are not fully elucidated. This research aimed to determine the effects of different nitrogen-potassium (NK) fertilizer levels on oil palm morphological characteristics, foliar nutrient content (FNC) and nitrate reductase (NR) activity of six oil palm seedlings of different parentage. Oil palm progenies designated as A-F was planted at the test plots and supplied with three NK fertilizer levels designated as T0 (0 kg Ammonium Sulphate (AS) and 0 kg Muriate of Potash (MoP) per palm), T1 (2.7 kg AS and 1.75 kg MoP per palm) and T2 (5.4 kg AS and 3.5 kg MoP per palm). Our findings indicated minimal impact of fertilizer application on oil palm growth rate. A significant (p<0.05) increase was observed in foliar nitrogen and potassium content from T1 fertilization with an average of 28% and 32%. Whereas, T2 caused only a small overall increase of 5% and 7%, respectively. Similar NR activity was recorded in most of the seedlings showing a reduced activity at the average of 18% when treated with T1 while drastically elevated when treated with T2 with a 41% overall increase. The similarity in parentage of each oil palm seedling plays a significant role in the overall reaction of seedlings towards fertilization. Although fertilization may not have a significant observable impact towards growth and foliar nutrient content, a significant response can be seen in the nitrate reductase reaction of the seedlings. Overall, the study indicates a slight favour towards T1 treatment based on the overall response of the seedlings
Hybrid active force control for fixed based rotorcraft
Get PDFDisturbances are considered major challenges faced in the deployment of rotorcraft unmanned aerial vehicle (UAV) systems. Among different types of rotorcraft systems, the twin-rotor helicopter and quadrotor models are considered the most versatile flying machines nowadays due to their range of applications in the civilian and military sectors. However, these systems are multivariate and highly non-linear, making them difficult to be accurately controlled. Their performance could be further compromised when they are operated in the presence of disturbances or uncertainties. This dissertation presents an innovative hybrid control scheme for rotorcraft systems to improve disturbance rejection capability while maintaining system stability, based on a technique called active force control (AFC) via simulation and experimental works. A detailed dynamic model of each aerial system was derived based on the Euler–Lagrange and Newton-Euler methods, taking into account various assumptions and conditions. As a result of the derived models, a proportional-integral-derivative (PID) controller was designed to achieve the required altitude and attitude motions. Due to the PID's inability to reject applied disturbances, the AFC strategy was incorporated with the designed PID controller, to be known as the PID-AFC scheme. To estimate control parameters automatically, a number of artificial intelligence algorithms were employed in this study, namely the iterative learning algorithm and fuzzy logic. Intelligent rules of these AI algorithms were designed and embedded into the AFC loop, identified as intelligent active force control (IAFC)-based methods. This involved, PID-iterative learning active force control (PID-ILAFC) and PID-fuzzy logic active force control (PID-FLAFC) schemes. To test the performance and robustness of these proposed hybrid control systems, several disturbance models were introduced, namely the sinusoidal wave, pulsating, and Dryden wind gust model disturbances. Integral square error was selected as the index performance to compare between the proposed control schemes. In this study, the effectiveness of the PID-ILAFC strategy in connection with the body jerk performance was investigated in the presence of applied disturbance. In terms of experimental work, hardware-in-the-loop (HIL) experimental tests were conducted for a fixed-base rotorcraft UAV system to investigate how effective are the proposed hybrid PID-ILAFC schemes in disturbance rejection. Simulated results, in time domains, reveal the efficacy of the proposed hybrid IAFC-based control methods in the cancellation of different applied disturbances, while preserving the stability of the rotorcraft system, as compared to the conventional PID controller. In most of the cases, the simulated results show a reduction of more than 55% in settling time. In terms of body jerk performance, it was improved by around 65%, for twin-rotor helicopter system, and by a 45%, for quadrotor system. To achieve the best possible performance, results recommend using the full output signal produced by the AFC strategy according to the sensitivity analysis. The HIL experimental tests results demonstrate that the PID-ILAFC method can improve the disturbance rejection capability when compared to other control systems and show good agreement with the simulated counterpart. However, the selection of the appropriate learning parameters and initial conditions is viewed as a crucial step toward this improved performance
Hybrid adaptive sliding mode control for quadcopter unmanned aerial vehicle
No full textQuadcopter unmanned aerial vehicle (UAV) systems are receiving remarkable attention from researchers due to their numerous applications, particularly at the current time in which the quadcopter unmanned aerial vehicles are playing a significant role in combating the COVID-19 pandemic. The quadcopter is a nonlinear and underactuated system, and such properties require an advanced control technique design to enable the quadcopter to achieve the assigned tasks precisely and successfully. The sliding mode control is among the best robust nonlinear control technique that can be implemented in the quadcopter to perform robust trajectory tracking. However, the drawback of the sliding mode control is the chattering phenomenon. Thus, this research aims to benefit the sliding mode control robust trajectory tracking meanwhile attenuating the unwanted chattering that creates critical problems such as the vibration in the quadcopter UAV mechanical parts and generating heat in the onboard electronic kits. The main objective of this work is to design a hybrid adaptive sliding mode control scheme for quadcopter systems considering the unwanted chattering attenuation induced by unbound parameter uncertainties and unknown disturbances meanwhile provide robust tracking. To implement the proposed control scheme, the dynamic equations of the quadcopter have been formulated and presented into two subsystems, the attitude, and the position dynamics subsystems. The hybrid proposed control scheme is composed of two controllers, an inner control loop and outer control loop. Firstly, the sliding mode controller has been proposed and assigned to act as an inner loop controller, where the improvement covered, the equivalent control, and the switching control terms in the sliding mode control law. The equivalent control term has been estimated and developed based on the Lyapunov approach. Essentially, the switching control term is a multiplication of a switching function and the switching gain. The switching function is approximated by an error function, while the switching gain is calculated based on an improved adaptive formula. Secondly, an interval type-2 fuzzy proportional integral derivative controller has been proposed and assigned to act as an outer loop controller to control the quadcopter position. The performance of the proposed hybrid adaptive sliding mode control scheme has been evaluated and investigated by Matlab/Simulink platform. The simulation results have been obtained in two different scenarios: Firstly, the performance of the proposed hybrid adaptive sliding mode control scheme has been evaluated considering only an ideal case where the parameter uncertainty and external disturbance are ignored. Secondly, the performance of the proposed hybrid adaptive sliding mode control scheme has been investigated in the presence of parameter uncertainty and external disturbance that influence the quadcopter operation. The simulation results have been performed for the quadcopter trajectory tracking in 6-DOFs. The obtained results prove that the proposed hybrid adaptive sliding mode control scheme provided a robust trajectory tracking with integral square error in the attitude and position have been improved by 37%, and 26% respectively, compared to the benchmark adaptive sliding mode control, and significantly attenuating the chattering impact
Hybrid numerical approach of finite difference and asymptotic interpolation methods for non-newtonian fluids flow
No full textPrevious research in the mathematical and physics fields has used computational or empirical approaches to analyse fluid flow problems. Therefore, in this thesis a hybrid numerical approach for non-Newtonian third- and fourth-grade fluid flow problems using the finite difference method and the asymptotic interpolation method are presented. The hybrid method is important for finding accurate results as the size of the problem domain increases to infinity. The finite difference method is used to discretize the nonlinear partial differential equation into a linear system. An asymptotic interpolation method is used to estimate nodal value as the size of the domain tends to infinity. The algorithm is coded using the MATLAB program. A polynomial function that fits the hybrid solution is used to calculate the error of the equation. Theoretical error analysis using truncation error in the finite difference method, right-hand side perturbation linear system, and right perturbation theorem is conducted to determine the norm and range of errors. An implicit numerical scheme of modified fluid problems with an exact solution has been achieved by adding an extra term to the partial differential equation. The norm of error between the hybrid method and exact solution is less than the norm of error between the finite difference method and exact solution. The theory of stability for third-grade fluid is carried out, and the numerical scheme is stable provided that the condition of modulus of the amplifier holds. The hybrid method is used to solve the constant acceleration of an unsteady magnetohydrodynamic third-grade fluid in a rotating frame. The analyses show that the increment of the magnetic and rotating parameters decreases the speed of motion and thus the velocity. The velocity increases with an increase in time. The unsteady magnetohydrodynamic fourth-grade fluid problem in the rotating frame is investigated. Increasing the elastic parameters increases the velocity of the fluid. The problem of heat transfer for third-grade non-Newtonian fluid flow with magnetic effect is addressed. The temperature drops by increasing the Prandtl number. It is noted that increasing the Grashof number increases the temperature and velocity. The obtained results have shown that the hybrid method is consistent, stable, and converges to the solution
Mosaic frequency selective surface with wideband response for the optically transparent and absorber applications
No full textThis study investigated the performance of a Mosaic Frequency Selective Surface (MFSS) structure for two different applications: optical transparency and absorber. The MFSS for optical transparency application is comprised of a polycarbonate substrate with permittivity, varepsilon_{r} of 2.9, and the MFSS for absorber application utilized a Polyethylene Terephthalate (PET) substrate with varepsilon_{r} of 2.7. The MFSS unit cell is composed of a conductive metallic element design that integrates the Koch fractal and the double hexagonal loop for the optical transparency application. Meanwhile, the resistive MFSS unit cell with sheet resistivity of 100 Omega/text{sq} is utilized for the absorber application. A Computer Simulation Technology (CST) Microwave Studio software is employed to carry out the calculation and frequency response analysis for both applications. Based on the results, it was concluded that the transparent MFSS yielded a wideband stopband and passband responses (fractional bandwidth (text{FBW}) > 50%) with a low cross-polarization (-37 dB), and a wideband absorptivity response was achieved with thin MFSS absorber. In addition, the simulated and measured responses of the transparent MFSS achieved well-fitted correlations. The findings indicated that the proposed MFSS unit cell able to provide wideband response for both applications
Modelling the significance of social support, theory of planned behaviour and trust for social capital growth in energy sectors
No full textThis study investigates the factors and theories that drive social capital in energy sector. Social capital can be procured and further developed for productive and mutual benefits, particularly for Malaysia's energy sectors with the rise of social commerce and the maturing of social media. In this study, a research framework was developed and evaluated to promote social capital. The framework defines the relationship between the Theories of Planned Behaviour (TPB) and Social Support Theory (SST) alongside Trust factors, stimulating social capital expansion in energy sectors. This research utilises PLS-SEM to examine the data gathered from employee in the energy sectors in Malaysia. The research demonstrates the presence of social capital when trust and social support exist among users and encourages positive changes and benefits in the aspects of productivity, efficiency, and profitability in energy sectors. In order to analyse the research factor's validity and its reliability, the study adapted a survey which was circulated to 100 respondents from the energy sector in Malaysia. Results show that the entire proposed factors are crucial in promoting social capital
Influence of agricultural activities on housing and settlement patterns of rural communities in Benue State Nigeria
Get PDFPhysical, social, and economic elements, such as agricultural occupation, impact the forms of house and settlement patterns such as shape, space enclosure, appearance, and organization. This research aims to investigate the impact of agricultural activities on the housing and settlement patterns of the Benue people of central Nigeria. The exploratory sequential research approach was utilized where qualitative and quantitative attributes and consequences were elicited based on the Means-End Chain mode. The study was done in stages between June 2020 and March 2022, with 24 individuals first interviewed and 474 nominal survey questionnaires completed and returned. Preliminary data checks for the subsequent 241 ordinal surveys returned to reveal a significant Bartlett's Test of Sphericity, a Kaiser-Meyer-Olkin value of 0.872, and a Cronbach's alpha of 0.934. While the interviews and nominal surveys provide considerable correlations between agricultural activities and the people's settlement patterns, statistical validations of the ordinal survey yield minute evidence of the associations. The conclusions of this study are consistent with prior studies, which connect agricultural activities to people's house form and settlement patterns. It is recommended that authorities make transformative efforts to nucleate the fragmented communities to free up more area for mechanized farming, combat insecurity, and reduce competition for territorial resources
Focal region ray tracing for slanted incident rays on spherical reflector antenna
Get PDFMulti beam antenna system is required at base station for fifth-generation (5G) mobile communication and also to cover large portions of field of view for the satellite antenna. A spherical reflector antenna is promising to give high gain directivity of each independent beams for its multiple beam capabilities. The study of the feed elements system is carried out by analysing the focus of slanted incident rays in receiving mode from 0° to 30° at step angle 10°. Simple analytical equations are derived to find the incident and reflected rays. This focal region of spherical reflector is studied in MATLAB program. Accuracy of the MATLAB results are validated by examining the focal region using an electromagnetic simulator, FEKO. The locus of feed of spherical reflector antenna for certain angles of the incident rays are presented in this study
Performance of hot mix asphalt incorporating treated crumb rubber and treated plastic additives using dry process
Get PDFPavement defect shortens the service life of mixture, demonstrated by failures such as cracking, rutting, and stripping. Incorporating additives into conventional mixture is an approach to improve its performance and service life. Therefore, this research was conducted in three phases using treated crumb rubber (TCR) and treated plastic (TP) as additives in the mixture. In the first phase, both additives were characterised using thermogravimetric analysis (TGA), field-emission scanning electron microscope (FE-SEM) and energy dispersive x-ray (EDX). Eight different percentages of TCR from 0.25 % to 5.0 % and six different percentages of TP from 0.25 % to 3.0 % were incorporated into a 14 mm nominal maximum aggregate size (AC14) mixture using a dry process. Marshall test was carried out to determine the optimum percentage of the additives. Results show that the mixtures of 0.75 % TCR and 0.75 % TP met all the required specifications and were selected as the optimum percentage. The mixtures with 0.75 % TCR and 0.75 % TP improved the fatigue cracking and rutting resistance compared to the conventional mixture. In the second phase, mechanical tests such as resilient modulus, dynamic creep, rutting and moisture damage of compacted and uncompacted mixtures and scanning electron microscope (SEM) were conducted to evaluate the performance of the mixture containing TCR and TP. Although the modified mixtures with both additives showed better performance than the conventional mixture, the TCR mixture was susceptible to rutting and moisture damage, while the TP mixture was identified with stripping potential. To overcome the issues, a combination of TCR and TP was investigated in the final phase. A mixture with 50 % TCR and 50 % TP shows 37 %, 44 % and 4 % improvement in the fatigue, rutting and moisture damage resistance, respectively, compared to the conventional mixture. It can be concluded that the combination of TCR-TP in mixture using dry process can be used as an alternative mixture to improve pavement performance