Communities in UTM Open Science
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Kesan luluhawa terhadap kekuatan ricih syal lempung dalam penentuan parameter kestabilan cerun
(Universiti Teknologi Malaysia, 2017) Idrus Muhamad Alatas
Syal lempung dalam keadaan semula jadi merupakan batuan lempung yang memiliki kekuatan ricih yang tinggi. Syal lempung yang terdedah kepada atmosfera dan hidrosfera menyebabkan kekuatan ricih berkurang dengan ketara. Perkara ini menyebabkan banyak kegagalan cerun berlaku di tanah syal lempung yang mana kaedah piawai untuk permasalahan tersebut masih belum ada. Oleh itu, kajian ini bertujuan menyiasat pengaruh luluhawa terhadap indeks dan ciri-ciri fizikal syal lempung serta penurunan kekuatan ricih puncak dan kekuatan ricih baki. Kajian ini juga bertujuan membangunkan kaedah yang tepat untuk menentukan dan mengaplikasikan parameter kekuatan ricih yang masih belum ada untuk permasalahan kestabilan cerun syal lempung. Pengambilan sampel tak terganggu syal lempung diperolehi daripada ujian galian dengan menggunakan acuan teras terbelah yang belum pernah digunakan. Sampel diuji di makmal untuk menentukan kekuatan ricih baki dan kemudiannya digunakan untuk menilai keadaan kes cerun di tapak pembinaan. Dua jenis hasil ujian ialah kekuatan ricih baki tanpa pelepasan tegasan dan kekuatan ricih baki dengan pelepasan tegasan. Pada kes cerun yang belum berlaku kegagalan, analisis kestabilan cerun menggunakan parameter kekuatan ricih yang sudah dipengaruhi luluhawa memberikan kejelekitan (c) antara 31% hingga 49%, manakala sudut geseran dalam (f) adalah antara 81% hingga 98% daripada keadaan semulajadi. Manakala pada kes cerun yang telah berlaku kegagalan, akan tetapi tidak berlaku penggalian, analisis kestabilan cerun yang menggunakan kekuatan ricih baki tanpa pelepasan tegasan memberikan hasil dengan kejelekitan baki (crp) adalah 21% hingga 28% dari kejelekitan puncak dan sudut geseran dalam (frp) adalah 32% hingga 45% dari sudut geseran dalam puncaknya. Pada kes cerun yang telah berlaku kegagalan, tetapi berlaku penggalian serta penimbunan semula, analisis kestabilan cerun menggunakan kekuatan ricih baki dengan pelepasan tegasan, kejelekitan baki (crf) adalah 2% hingga 9% dari kejelekitan puncak dan sudut geseran dalam (frf) adalah 19% hingga 24% dari sudut geseran dalam puncaknya. Hasil ujian kekuatan ricih baki yang diperolehi di makmal disahkan dengan penentuan kekuatan ricih baki yang berlaku pada kes kegagalan cerun di jalan tol Semarang Bawen STA 19+250. Analisis balik dengan kaedah elemen terhingga (FEM) dan kaedah had keseimbangan (LEM) telah mengesahkan bahawa ujian kekuatan ricih baki yang diperoleh di makmal dengan kaedah yang disyorkan telah membuktikan hasil yang cemerlang. Kajian ini mencadangkan ujian kekuatan ricih melalui proses luluhawa di makmal adalah sesuai untuk kejuruteraan rekabentuk rancangan kestabilan cerun pada tanah syal lempung di masa hadapan.
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Task oriented feature extraction for complex human activity recognition
(Universiti Teknologi Malaysia, 2022) Mohammed Mobark Salem Wahdeen
Human Activities Recognition (HAR) using mobile phone devices provides valuable contextaware information about the type of activities individuals perform within a time interval. HAR leverages sensory data available on today's sensor-rich, cheap, and portable mobile phones. It enables mobile phones to provide personalized support for many healthcare and well-being applications. It also has significant contributions to robotic, homeland security and smart environments. However, current recognition systems based on mobile phone sensors have observable issues in recognizing composite activities that occur concurrently or interleave i.e., complex activities, limiting their use in real-world applications. In those activities, the existence and variations of each activity as well as the order and length may vary. In this research, the issues of low recognition accuracy and high computing cost of complex human activities using mobile phone sensors are addressed. The composition and variations of human activity are examined as factors that impact the complexity of activity recognition. This research proposes to increase the quality of extracted features to increase the recognition accuracy with less resource consumption. It proposes extracting the wrist velocity as a feature for recognizing the performing arm’s complex activity. The wrist velocity feature is task oriented. Using the task-oriented wrist velocity feature will help to reduce recognition errors and therefore increase recognition accuracy. For this purpose, an extraction method for the wrist velocity feature is developed. In addition, the developed method is applied to recognize complex human activities using the Complex Activity Recognizer through Wrist velocity system (CARWV). Firstly, the extraction method begins by integrating the accelerometer and gyroscope data of the smartphone, which is placed on the upper arm and forearm. The integrated data is used to calculate the rotational angles of the upper arm and forearm. Then, the calculated rotational angles and lengths of the upper arm and forearm are used to calculate the position and the velocity of the wrist while performing the activity. Secondly, in the proposed recognition system (CARWV), the complex activity is broken into tasks that are represented by basic arm movements. The wrist velocity while performing the basic arm movements is extracted. The decision tree classifier is used to recognize the basic arm movements through the extracted feature. Then, the existing and order of recognized basic arm movements in the complex activity are used as features for recognizing the complex activity by measuring the similarity using the distance metric. The experiments demonstrate the validity of the task-oriented property of the extracted feature. The experiments also show increased recognition accuracy when using the proposed system up to 86% over performance for the state-of-the-art works, with 13 sec execution time and 31264 kb allocated memory in a notebook computer with Core i7 processor and 8GM memory. This study can facilitate future research in other fields where performance and limited resources are critical quality factors such as robotics and Wireless Sensor Networks (WSN).
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Ergonomic design parameters for Malaysian car driver seating position
(Universiti Teknologi Malaysia, 2017) Rashid, Zuli'zam
A key element in an ergonomically designed driver workspace of a car is the correct identification of seating position and posture accommodation. Current practice by the automotive Original Equipment Manufacturer (OEM) is to utilize the Society of Automotive Engineering (SAE) standard practice and guidelines in the design process. However, it was found that utilizing such guidelines which were developed based on the American population, do not fit well with the anthropometry and stature of the Malaysian population. This research seeks to address this issue by reviewing the existing standard practices of Design Package and Ergonomic for seating position and accommodation used by a Malaysian automotive manufacturer, Perusahaan Otomobil Nasional (PROTON), and to subsequently propose a new design parameters which better fit the Malaysian population. In the first stage, 210 respondents participated in the anthropometry measurement study to determine the range of sizes for the Malaysian population. In addition, 62 respondents were involved for the driver seating position and accommodation study in the vehicle driver workspace buck mock-up survey and measurements. The results have shown that the Malaysian population are generally shorter if compared with the SAE J833 standard specification, especially for the lower body segments. From the accommodation study, it was found that the Malaysian driver preferred to seat forward, which is probably due to the shorter limb dimensions in the thigh length, buttock length, knee length and foot length. In second stage, questionnaire survey and measurement were used to develop a new design parameters and standards for driver seating positioning and accommodation model based on the Malaysian population. Statistical regression analysis was used to assist in this design parameters development. The statistical model developed was validated by comparing the calculated value of Seating Reference Point of X axis (SgRPx) with actual measurement values measured during respondents sitting in the mock-up. The result shows the difference between the calculated and measured values was within 10 %, indicating that the equation is acceptable. The findings of research are expected to enhance and improve the design guidelines / standard reference for the local automotive industry
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Laminar flow heat transfer enhancement in multy-start spirally corrugated tubes
(Universiti Teknologi Malaysia, 2016) Zaid Sattar Kareem
Heat transfer plays an important role in many aspects of human life, especially the forced convection type. Hence, it has become very important to invest resources and efforts in this vital field to make some difference. Recently, the trend of using compact heat transport devices is of great interest to obtain an efficient, low cost and small size product which requires less production time with fewer efforts. Employing of artificial roughness, such as corrugation, for heat transfer enhancement in heat exchanger and other industrial thermal devices have shown promising results, with good performance reliability at lower cost. Therefore, the current study aimed to investigate experimentally and numerically the heat transfer enhancement and pressure drop increase in tubes with a superior type of corrugation i.e. the spiral corrugation. The flow of ionised water as working fluid in tubes at low Reynolds number was constructed to investigate the laminar flow regime of 100= Re=1300. Five spirally corrugated tubes and one smooth tube under constant wall heat flux boundary condition with various thermo-physical properties was investigated through experimental test and computational fluid dynamics simulation. Different corrugation parameters, such as corrugation height to diameter and corrugation pitch to diameter ratios were studied in different corrugated tube sizes. The results showed that the severity index, which combines the effect of both corrugation height and pitch, has great effects on heat transfer rate, friction factor, and thermal performance of the flow inside spirally corrugated tubes. The heat transfer enhancement was in the range of 1.3-2 compared to a smooth tube, accompanied with an increase in friction factor in the range 1.1-1.9. The thermal performance range was found to be improved by 1.2-2.08 times. The heat transfer and friction factor correlation are proposed
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Maghemite filled poly-vinyl alcohol nanofibres for tissue engineering scaffold.
(Universiti Teknologi Malaysia, 2016) Ngadiman, Nor Hasrul Akhmal
Maghemite (y-Fe2O3) nanoparticle with its unique magnetic properties has the potential to be used in biomedical applications. In this study, y-Fe2O3 was mixed with polyvinyl alcohol (PVA) in order to enhance cell growth which is required for tissue engineering (TE) scaffold. Electrospinning was chosen to be the main process in this study due to its ability to form fibers at nanometer scale and it can mimic the dimensions of the extracellular matrix (ECM) of human tissue. However, the major challenge faced is the limitation on its thickness of the electrospun mats produced. Thus in this study a 3D TE scaffold was fabricated from a novel biomaterial (PVA/y- Fe2O3) using a combined 3D printing with thermally induced phase separation (TIPS) and electrospinning processes. Design of experiments (DOE) was used to determine the optimum parameter settings for the electrospinning process so as to produce electrospun mats with good mechanical properties and porosity. The input factors of the electrospinnning process were the nanoparticles content, voltage, flow rate, spinning distance (tip to collector) and the rotating speed while the responses considered were Young’s Modulus and porosity. Maximum Young’s Modulus achieved was 273.51 MPa while maximum percentage of porosity achieved was 90.85%. The layer of electrospun nanofibers was then wrapped around the 3D PVA/y- Fe2O3 TE scaffold which was developed by combining 3D printing with TIPS. The characteristics and biocompatibility performance of the optimum PVA/y-Fe2O3 electrospun nanofiber mat and 3D structure were investigated. The developed 3D structure scaffold was again tested for its Young’s Modulus and was found to be 1.74 ± 0.17 GPa. Results also showed that the material developed has good biocompatibility properties. The rate of cells growth for the novel material (PVA/y- Fe2O3) was faster than the controlled material (only PVA) indicating that it is biocompatible. In conclusion, the developed 3D PVA/y-Fe2O3 nanofibrous scaffold has good mechanical and biocompatibility properties suitable for TE scaffold.