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Experimental and numerical modeling of outrigger systems of tall building structures
Full text linkThe tall building’s height recently has exceeded a thousand meters. An appropriate lateral load resisting system to drift-control seems necessary. Considering that the lateral deflections play a vital role in selecting the type of tall building structures. Top-drift in tall buildings has not yet been entirely resolved for seismic demands. That is way, utilizing the structural outrigger systems is one of the most efficient structural systems to enhance the structure's lateral stiffness and minimize the top-drift without increasing the building's components sizes and mass it will need. This study aims to specify the lateral resisting responses of conventional structural outrigger models through experimental works. A new type of outrigger model was proposed to compare its effectiveness with the conventional models. Finally, to optimize the parameters affecting the new outrigger model's lateral response is proposed through the Finite Element Method (FEM). A total of eight 3D models including three types of structural core models (no outrigger), two types of single outrigger models, two types of multi outrigger models, and a proposed new outrigger model, were experimented using a quasi-static cyclic test. The models are termed the Core Models (Core-1,2 and 3), Opti-models (1-Out, 2-Out), Conv-models (Cap-Out, 2-Out), new model (DevOut) and FE Dev-Out. This research, inspired by the 2D analytical method with an idealized pattern, has been used to advance to 3D experimental modeling to achieve more reliable results. The hysteresis curves have been calculated to obtain the initial lateral stiffness, effective stiffness, ultimate lateral strength, ductility ratio, energy dissipation capacity, and failure mechanism in all experiments through the quasi-static cyclic test models. Results indicated that the outrigger systems' optimal forms failed at the first outrigger's upper level while the conventional forms and core models failed at the base. The 2-Out optimal form up to 140% have higher effective stiffness than 1- Out, and Cap-Out 36% higher than 2-Out conventional form, while the Dev-Out form is 31% higher than the 1-Out Opti model. The Cap-out 6% is higher than the 1-Out Opti form as well. The energy dissipation of the 2-Out conventional form has the highest level by 686.1 kN.mm, while the Dev-Out model has the lowest value by 297.7 kN.mm than other outrigger forms. The 2-Out conventional form by 6.73 is ductile, and the 2-Out Opti model by 3.84 ratios has a second-place than other forms. The proposed new model can increase the effective lateral stiffness by 2.2 times at the develop-outrigger location due to added outer peripheral columns. The FE Dev-Out model to reduce the top-drift was optimized when the outrigger is placed at 0.4H from the top of the model. Also, the base moment was minimized if the outrigger is placed at the mid-height and base position range. In final, the developed 3D method compared to the traditional 2D methods indicated a significant difference in the conventional outrigger forms' performance with optimal forms under lateral loads, stiffness, ductility, and energy dissipation in tall building structures
Hacking countermeasure framework for oman computer emergency readiness team using delphi approach
Full text linkRecent security attacks have breached some of the most secure networks around the world causing damages, stealing information, and data corruption. This devastating situation has led security experts to question the effectiveness and reliability of the present security controls against the hacking attacks. Thus, there is a need to prevent systems hacking and fulfil managerial concerns about security risks. This research focuses on the design and development of Hacking Countermeasure Framework (HCF) using Delphi method that combines quantitative and qualitative research questionnaires to address problems associated with the lack of hacking anticipation, hiding and deception, and Defense-in-Breadth (DiB) techniques. This research was conducted via an online, anonymous, and asynchronous six-round Delphi methodology adapted from the classical Delphi method with a pre-selected security experts panel. The study was arranged in four Delphi phases. Phase one covers analysis of studies that have used pre-Delphi to explore hacking threats and the provided recommendations for anti-hacking. Phase two covers derivation of factors for identifying anti-hacking factors and their relationships. Phase three covers development of a framework to prevent systems hacking and fulfil managerial concerns regarding security risks. Finally, phase four covers validation of the research deliverables using triangulation with five processes, namely study cases, interviews, discussion workshop, review and quality assurance by cyber security experts, and approval by CERTs. The findings of this research confirms the importance of hacking anticipation, hiding and deception, and DiB in a hacking countermeasure process and provides enticing clues regarding the role of these three factors in the hacking countermeasures. Despite recent calls for the replacement of Defense-in-Depth (DiD), this research also confirms that DiD plays a vital role in anti-hacking processes. Moreover, a clear linkage is identified between hacking risk assessment, anti-hacking auditing, and anti-hacking compliance. Furthermore, the validation of framework confirms that hacking countermeasure improves through the induced solutions for DiB, and deception and hiding techniques. The HCF is useful for both academia and industry and can contribute to theory and practice of hacking anticipation, DiB, and hiding and deception
Selective joint motion recognition using multi sensor for salat learning
Full text linkOver the past few years, there has been significant attention given on motion recognition in computer vision as it has a wide range of potential applications that can be further developed. Hence, a wide variety of algorithms and techniques has been proposed to develop human motion recognition systems for the benefit of the human. Salat—an essential ritual in Muslim daily life which helps them be good Muslims—is not solely about the spiritual act, but it also involves the physical movements in which it has to be done according to its code of conduct. The existing motion recognition proposed for computing applications for salat movement is unsuitable as the movement in salat must be performed in accordance to the rules and procedures stipulated, the accuracy and sequence. In addition, tracking all skeleton joints does not contribute equally toward activity recognition as well as it is also computationally intensive. The current salat recognition focuses on recognizing main movements and it does not cover the whole cycle of salat activity. Besides, using a wearable sensor is not natural in performing salat since the user needs to give absolute concentration during salat activity. The research conducted was based on the intersections of technological development and Muslim spiritual practices. This study has been developed utilizing dual-sensor cameras and a special sensor prayer mat that has the ability to cooperate in recognizing salat movement and identifying the error in the movement. With the current technology in depth cameras and software development kits, human joint information is available to locate the joint position. Only important joints with the significant movement were selected to be tracked to perform real-time motion recognition. This selective joint algorithm is computationally efficient and offers good recognition accuracy in real-time. Once the features have been constructed, the Hidden Markov Model classifier was utilized to train and test the algorithm. The algorithm was tested on a purposely built dataset of depth videos recorded using a Kinect camera. This motion recognition system was designed based on the salat activity to recognize the user movement and his error rate, which will later be compared with the traditional tutor-based methodology. Subsequently, an evaluation comprising 25 participants was conducted utilizing usability testing methods. The experiment was conducted to evaluate the success score of the user’s salat movement recognition and error rate. Besides, user experience and subjective satisfaction toward the proposed system have been considered to evaluate user acceptance. The results showed that the evaluation of the proposed system was significantly different from the traditional tutor-based method evaluation. Results indicated a significant difference (p < 0.05) in success score and user’s error rate between the proposed system and traditional tutor-based methodology. This study also depicted that the proposed motion recognition system had successfully recognized salat movement and evaluated user error in salat activity, offering an alternative salat learning methodology. This motion identification system appears to offer an alternate learning process in a variety of study domains, not just salat movement activity
Triple scheme based on image steganography to improve imperceptibility and security
Full text linkA foremost priority in the information technology and communication era is achieving an effective and secure steganography scheme when considering information hiding. Commonly, the digital images are used as the cover for the steganography owing to their redundancy in the representation, making them hidden to the intruders. Nevertheless, any steganography system launched over the internet can be attacked upon recognizing the stego cover. Presently, the design and development of an effective image steganography system are facing several challenging issues including the low capacity, poor security, and imperceptibility. Towards overcoming the aforementioned issues, a new decomposition scheme was proposed for image steganography with a new approach known as a Triple Number Approach (TNA). In this study, three main stages were used to achieve objectives and overcome the issues of image steganography, beginning with image and text preparation, followed by embedding and culminating in extraction. Finally, the evaluation stage employed several evaluations in order to benchmark the results. Different contributions were presented with this study. The first contribution was a Triple Text Coding Method (TTCM), which was related to the preparation of secret messages prior to the embedding process. The second contribution was a Triple Embedding Method (TEM), which was related to the embedding process. The third contribution was related to security criteria which were based on a new partitioning of an image known as the Image Partitioning Method (IPM). The IPM proposed a random pixel selection, based on image partitioning into three phases with three iterations of the Hénon Map function. An enhanced Huffman coding algorithm was utilized to compress the secret message before TTCM process. A standard dataset from the Signal and Image Processing Institute (SIPI) containing color and grayscale images with 512 x 512 pixels were utilised in this study. Different parameters were used to test the performance of the proposed scheme based on security and imperceptibility (image quality). In image quality, four important measurements that were used are Peak Signal-to-Noise Ratio (PSNR), Structural Similarity Index (SSIM), Mean Square Error (MSE) and Histogram analysis. Whereas, two security measurements that were used are Human Visual System (HVS) and Chi-square (X2) attacks. In terms of PSNR and SSIM, the Lena grayscale image obtained results were 78.09 and 1 dB, respectively. Meanwhile, the HVS and X2 attacks obtained high results when compared to the existing scheme in the literature. Based on the findings, the proposed scheme give evidence to increase capacity, imperceptibility, and security to overcome existing issues
Parametric and thermal analysis of horizontal jet flames
Full text linkJet fire occurrence in an industrial installation can be severe as it can trigger a series of related events. The main hazard associated with jet fire occurrence is the heat released by radiation, which can be very high at a very short distance. The evaluation of jet flame geometry could assist the safety officer to prevent flame impingement on the nearby equipment and therefore, reduce the inventory losses and structural collapse. Previous observation indicates that the horizontal jet fire poses more significant thermal hazards as compared to that of other types of fire. However, to date, scarce and limited data are available as a reference on a jet flame for horizontal orientation, particularly for parametric characteristics and correlation model development. Thus, this study aims to investigate the thermal radiation and geometrical flame features of buoyant horizontal jet fires. Two scenarios were considered for this work i.e. free jet fires and jet fire impingement. This study used propane as the fuel that was released from a circular nozzle with a diameter of 7.15 mm and 9.8 mm. The jet fire tests were performed with different ranges of flow rates between 30 – 600 g/min at a release distance of 0.8 m and 1.2 m. Differences in flame shapes are evaluated with the use of the MATLAB. Meanwhile, linear correlations of the main geometrical parameters of interest are determined as a function of Reynolds number and Froude number (i.e. lift-off distance, projected flame length, flame height, flame trajectory, flame width). For thermal radiation analysis measurement, semi-empirical model prediction of the line-source (LSM) model was adopted to account the flame geometrical features. From the findings, it was found that the lift-off length, Lf estimation from this work was in a good agreement with Bradley’s correlation for both free and impinging jet release with R2 of 0.95. Due to the flame Froude number value is between 0.8 to 3.5, it signifies that the flame is controlled by buoyancy and momentum, thus flame trajectory, Lt was proposed to be used to estimate the radiant heat release. Using the flame trajectory, Lt for radiant heat estimation, it was observed that Lt could give a better prediction of radiant heat release for free jet fire release with R2 of 0.99 as compared to projected flame length, Lp (horizontal kite flame shape) (R2 = 0.94). It also gave consistent results with the measured data for an impinging jet release with R2=0.99 for all release scenario, using a similar approach. It can be deduced that the modified LSM using the flame trajectory parameter is a reliable method for radiant heat prediction, on both scenario in this work; free jet release and impinging jet. Implicitly, it can be suggested that the applicability of LSM becomes wider to include the effects of buoyancy and impingement scenario. Furthermore, it offers additional provision to determine the minimum spacing distance of the equipment sitting for the plant layout
Pouteria campechiana pulp ethanol-water extract as a bioactive ingredient for topical delivery of oil-in-water nanoemulsion
Full text linkThe aging process is an inevitable natural course of each human, affecting the entire body, notably the skin's surface. Numerous over-the-counter nanoformulations are available, but none has considered Pouteria campechiana (Pc) extract as a source of the active ingredient in the formulation. In this study, the hydrophilic fraction of the Pc fruit extract was used as an O/W formula for topical application to the human skin. Fatty acid analysis showed that over 18 types of fatty acids were present in the Pc pulp, with the Pc oil showing an acid value of 6.451. The proximate analysis gave an 8.4% moisture content, 1.7% ash, 4.0% protein, 1.0% fat, 84.9% carbohydrates, with a total energy value of 364.60 Kcal/100g. Next, ultrasonic-assisted extraction (UAE) used in this study facilitated satisfactory extraction of phenolic compounds from the Pc pulp. Under optimized UAE conditions (extraction time = 30 min, extraction temperature = 25 °C, ratio of ethanol:water = 60%, v/v), the experimental response surface methodology-assisted optimization, a maximum total phenolic content (TPC) of 1162.80 mg GAE/100 g (DW) was obtained. In the screening process, compositions of jojoba oil (JO), grapeseed oil (GSO), Tween 80, and glycerol (GLY) at 6–12%, 20–26%, 5–7%, and 25–27% gave good particle sizes and PdI between 280–420 nm and 0.18–0.44, respectively. The resultant Pc extract showed a percentage 2,2-diphenyl-1-picrylhydrazyl (DPPH) inhibition at 82.91%, IC50 of 2.344 mg/mL, ferric reducing antioxidant power (FRAP) value of 836.30±30.60 μmol/100 g DW, and total flavonoid content (TFC) of 813.29 mg QE/100 g. In the D-optimal Mixture Experimental Design experiment, the optimized Pouteria campechiana extract nanoemulsion (OPT-PcE-Ne) formulation comprised JO amount (6.25%), GSO amount (34.38%), T80 (14.06%), and GLY (45.31%) at fixed 0.5% phenoxyethanol, 5% PcE, 2% xanthan gum (XG), and 0.5% perfume oil. The OPT-PcE-Ne yielded the lowest particle size at 222±0.61 nm and PdI of 0.16. The OPT-PcE-Ne gave good organoleptic and stability profiles by remaining creamy white, without any color change for up to 90 days, with a zeta potential of –32.6±0.5 mV and an acceptable pH (4.81±0.02). The OPT-PcE-Ne droplets were averagely sized at 93.46−183.13 nm in the transmission electron microscopy (TEM) micrograph and gave conductivity of 0.22 μS/cm. The OPT-PcE-Ne rheology followed a Bingham plastic behavior, suggesting that the cream must be applied to the skin in successive layers. In the accelerated tests, phase separation in the OPT-PcE-Ne was absent in the ultracentrifugation and freeze-thaw cycle studies. Next, samples stored for 6 weeks showed mean particle size and PdI between 155–315 nm and 0.16−0.28 for 4±2 °C, 415–150 nm and 0.16−0.26 for 28±2 °C and 125–295 nm and 0.14−0.45 for storage at 50±2 °C. The general non-linearity for the OPT-PcE-Ne stored at 4±2 °C, 28±2 °C proved the system was not destabilized by coalescence but more so by Ostwald ripening when stored for long durations at 28±2 °C (R2=0.7753). The OPT-PcE-Ne exhibited a release of ~0.18% of PcE in the 0–6 h duration, with a maximal level of 5.17% after 24 h. Pertinently, the OPT-PcE-Ne was also free from microorganisms- and heavy metal contamination. In the sensory evaluation study, the OPT-PcE-Ne exhibited the highest color and texture scores compared to other commercial lotions scoring 7.3 and 6.6, respectively. However, the scent was the lowest-rated factor at a collective scale of 6.1. The study findings supported the use of the PcE as a natural-based ingredient in cosmeceuticals and the OPT-PcE-Ne as a topical lotion on human skin
Microstructures of soft clay stabilized with coal ash and cement
Full text linkAs the growth of industries increase electricity demand, the amount of coal ash and waste produced by power plants has significantly increased. Malaysia alone produces approximately 11 million tons of coal annually. For every 2.9 million metric tons of coal that is burned, 1.2 million metric tons of coal ash is produced. Therefore, there is a pressing need to reutilise coal ash waste in a sustainable matter for the good of the environment. The purpose of this study was to identify the macrostructure and microstructure behaviour of marine clay that had been stabilised with coal ash and a minimal amount of ordinary Portland cement (OPC) for use as a subgrade layer in road construction. Very few studies have been conducted on contamination analysis of coal ash as well as mixtures of coal ash and marine clay. In fact, this present study is the first to investigate the performance of marine clay that has been treated with coal ash and OPC with a pre-assessment of load repetition behaviour. The physical properties of all the materials used in this study were examined where necessary. The treated marine clay samples were subjected to an unconfined compressive strength (UCS), California bearing ratio (CBR) as well as a mini tracker tests. Microstructural tests; such as X-ray diffraction (XRD) analysis and energy dispersive X-ray (EDX) spectrometry using a field emission scanning electron microscope (FESEM); as well as toxicity characteristic leaching procedure (TCLP) were also performed. The results of the physical property tests indicated that the use of stabilisers; such as coal ash and OPC; improved the properties of marine clay. The results of the UCS test concluded that the 15% 50BA:50FA sample was the most effective stabiliser as it satisfy the minimum requirements of the Standard Specification for Roadworks for stabilised subgrade layers. During microstructural analysis, XRD analysis showed that the mineral composition intensity of untreated marine clay decreased as the curing duration increased. A new mineral; calcium aluminium silicate hydroxide hydrate (CASH, Ca5Si5Al(OH)O17.5) was also found to form. The FESEM results showed the surface particles of treated marine clay seemed denser with fewer voids in the structure. In line with the findings of the XRD and FESEM tests, the EDX results confirmed that cementitious product formed was CASH. During the performance testing for subgrade evaluation, the CBR of treated marine clay increased unlike untreated marine clay in both soaked and unsoaked conditions. Of the treated marine clay samples, only the 15% 50BA:50FA sample at Day 7 had a CBR of 12.8%, which was above the minimum 12% required by the Standard Specification for Road Works in Malaysia. The findings of the mini tracker test indicated an increase in the number of cycles when both soaked and unsoaked conditions as well as untreated soil samples were compared. During the contamination analysis, the elemental concentrations of all three samples (fly ash, bottom ash, and treated marine clay) were found to satisfy the regulatory limits outlined by the US Department of Environmental (DOE). However, only the levels of cadmium, selenium, and silver detected in all three samples were within the regulatory limits of the National Standard for Drinking Water Quality. Therefore, marine clay stabilised with coal ash and OPC not only increases in strength but performs better. Moreover, treated marine clay is also safe for the environment
The influence of studying from home, stress level, and ability to use technology toward learning achievement during the COVID-19 pandemic: a case study in Indonesia
No full textThe COVID-19 pandemic has caused drastic changes to all aspects of life, including studying from home, the ability to use technology, and learning achievement in Indonesia. This study aims to analyse the effects of studying from home, the ability to use technology, and the level of stress on student learning achievement in Indonesia during the pandemic, where all students must learn from home. Data collection was conducted by issuing an online survey to 107 college students aged 18 to 55 in Indonesia. The data processing found that studying from home had a significant influence on stress levels and the ability to use technology. However, studying from home does not directly influence learning achievement, while stress and the ability to use technology do not directly correlate with each other. Interestingly, the indirect effects of studying from home on learning achievement are significant when stress and the ability to use technology mediate the relationships. This indicates that, although the pandemic is stressful for students as it forces them to isolate themselves at home and to miss out on face-to-face learning on campus, it has enhanced their ability to use technology and thus positively reinforced learning achievement. The result indicates that, in terms of learning achievement, students work "better under pressure" with their enhanced ability to use technology resulting in improved learning achievements. Consequently, the increasing ability to use technology when learning from home, the obstacles in knowledge transfer can run smoothly, and this hopefully reduces students' stress levels in the long term
Recent progress on the sea-level rise over the marginal seas in Southeast Asia
No full textThis paper reports the recent progress of sea-level rise (SLR) over the critical region of Southeast Asia (SEA) that is vulnerable to climate change. While many papers report the SLR on local scales (e.g., Malaysia, Indonesia, Vietnam, etc.), studies on understanding the SEA regional impact of SLR have yet to be reported, which has become the motivation of this paper. A literature review has been adopted to formulate the recent progress of SLR in the studied region. Besides global factors, we identified five (5) local factor drivers contributing to the SLR over SEA: 1) El-Nino and La-Nina, 2) seasonal monsoon, 3) wind-driven circulation variability/North Pacific Decadal Oscillation, 4) Indian Ocean dipole, 5) tectonic uplift and subsidence due to earthquake. The satellite altimeters and tide gauges have become major techniques for estimating SLR in the region due to the long-term data availability, except in regions with active seismic (e.g., Indonesia), tide gauge data gaps are crucial. Based on the Jason series altimeters (2002-2018), the SEA relative SLR is reported to be accelerating (2-6 mm/yr), which is critically beyond the global mean SLR (3.6 mm/yr between 2006 to 2015). Celebes Sea (6.05 ± 0.78 mm/yr), Sulu Sea (5.64 ± 0.64 mm/yr) and South China Sea (3.88 ± 0.49 mm/yr) record high SLR exceeding the global value, while Malacca Strait (2.67 ± 0.81 mm/yr) records slightly lower. Several cities (e.g., Surabaya, Jakarta, Benoa, Semarang Indonesia, and Ko Sichang and Ko Mattaphon Thailand) record extremely high SLR beyond 5 mm/yr
A novel approach for reducing actuators in soft continuum robots and manipulators
No full textSoft continuum robots and manipulators are elongated structures that employ several actuators to move and articulate their bodies. The dexterity of these mechanisms is directly related to the number of actuators they employ; a larger number of actuators increase dexterity. However, increasing the number of actuators results in a higher cost, increased complexity, and reduced reliability. This paper presents an approach to reduce the number of required actuators in soft continuum robots or manipulators while maintaining the same level of dexterity. The approach is based on employing fewer actuators in a specific configuration enabling the robot or manipulator to access the same workspace as previously achievable with the conventional models. The presented approach is thought to transform the design methodology of continuum robots and manipulators, thus reducing their cost, and complexity, while improving their reliability