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STRATEGIES TO REDUCE THE NUMBER OF SEVERELY INJURED VICTIMS IN ADOLESCENT MOTORCYCLE RIDERS
Get PDFStatistical data in 2021 in Indonesia shows that the number of accident victims reached 103,645 cases. Around 25% of these accident victims were underage drivers. For this reason, efforts must be made to minimize the number of accident victims, especially avoiding severe injuries. The criteria for respondents are motorcycle riders aged 12 - 25 years who are still categorized as adolescent riders. The data collection was carried out by interviewing respondents for approximately 10 minutes. For data analysis, the number of respondents used was 308 respondents. The location for data collection was Riau Province, Indonesia. The data was analyzed by Bayesian network. To get a good model, the basic model was validated. The number of respondents used to validate this model was 107 respondents. The results of the analysis show that the probability of an adolescent driver to experience severe injury is 27% and mild injury is 73%.Scenario 1 shows that poor driving performance will increase the probability of severe injury by 3%.Scenario 2 shows that driver fatigue will increase the probability of severe injury by 3%.Scenario 3 shows that drivers who conduct traffic violations will increase the probability of severe injury by 5%.Scenario 4 shows that drivers who perform long trips(more than 1 hour) increase their fatigue from 28% to 60%, which also increases the probability of severe injury by 1%.Scenario 5 shows that late night driving (between 24:00 – 06:00) not only increases the probability of fatigue but also increases the probability of severe injury by 1%.Strategic steps to reduce severe injury among adolescent motorcyclists include driving with good performance, avoiding fatigue-inducing conditions, abiding by all traffic rules, and avoiding driving between the hours of 24:00-06:00.
ABSTRAK: Data statistik pada tahun 2021 di Indonesia menunjukkan jumlah mangsa kemalangan mencapai 103,645 kes. Kira-kira 25% mangsa kemalangan ini adalah pemandu bawah umur. Oleh itu, usaha perlu dilaksanakan bagi meminimumkan mangsa kemalangan, terutama dalam mengelakkan kecederaan parah. Kriteria responden adalah penunggang motosikal berumur 12 - 25 tahun yang masih dikategori sebagai penunggang remaja. Pengumpulan data dijalankan dengan menemu bual responden selama lebih kurang 10 minit. Analisis data ini melibatkan 308 orang responden. Lokasi pengumpulan data adalah di Riau, Indonesia. Data dianalisis dengan rangkaian Bayesian. Bagi mendapatkan model terbaik, model asas telah disahkan. Bilangan responden yang terlibat dalam mengesahkan model ini adalah seramai 107 orang responden. Dapatan kajian menunjukkan kebarangkalian pemandu remaja yang mengalami kecederaan parah adalah 27% dan cedera ringan sebanyak 73%. Senario 1 menunjukkan pemanduan tidak berhemah akan meningkatkan kebarangkalian cedera parah sebanyak 3%. Senario 2 menunjukkan bahawa memandu dalam keadaan letih akan meningkatkan kebarangkalian cedera parah sebanyak 3%. Senario 3 menunjukkan bahawa pemandu yang melanggar peraturan lalu lintas akan meningkatkan kebarangkalian cedera parah sebanyak 5%. Senario 4 menunjukkan pemandu yang melakukan perjalanan melebihi 1 jam akan meningkatkan keletihan dari 28% kepada 60%, juga menyumbang kepada peningkatan kebarangkalian cedera parah sebanyak 1%. Senario 5 menunjukkan bahawa pemanduan lewat malam (antara 24.00 – 06.00) bukan sahaja meningkatkan kebarangkalian keletihan tetapi juga meningkatkan kebarangkalian cedera parah sebanyak 1%. Langkah strategik bagi mengurangkan kecederaan parah di kalangan penunggang motosikal remaja termasuk: memandu dengan berhemah, tidak memandu dalam keadaan letih, mematuhi segala undang-undang jalan raya dan mengelak dari memandu pada jam 24.00 hingga 06.00
Functional Metagenomics Approach for Discovery of Novel Cold-Active Protease from the Antarctic Region
Get PDFThe structural complexity of bacterial life makes most of it impossible to culture. Functional metagenomics approaches overcome the limitations of a culture-based approach in exploring and assessing the genetic materials of uncultured microbes. The objective of this study was to identify clones with cold-active proteases through functional metagenomics. In this work, the environmental DNA (eDNA) isolated directly from Antarctic soils was ligated into the pCC1FOS fosmid vector, transformed into EPI300-T1R E. coli host cells, and screened for proteolytic enzymes. Positive protease-producing clones were identified and isolated on skim milk agar supplemented with chloramphenicol and arabinose. This clone harbored a fosmid, pCC1FOS, which has a 48.5 kb insert that has been completely sequenced in both directions. Further analysis of the insert showed 70 NODEs. The NODE_42 encoded hypothetical protein of 297 amino acids showed a significant match to Peptidase M23 and PG-binding 1 proteins families. A three-dimensional model of the predicted protease was generated based on the known mesophilic protease of Neisseria meningitides (PDB: 3SLU). The structural alignment showed 27.07 % similarity with RMSD value of 0.402 Å based on 58 aligned residues. The active site residues were identical, but major deletions were observed in the predicted proteases. This predicted protease showed higher activity at -20 °C and 20 °C than the positive control (protease from bovine pancreas). Functional metagenomics is a promising approach in the discovery of cold-active protease with low homology to the known sequences and expressed in the host cell that has the potential for bioprospecting in low-temperature applications.
ABSTRAK: Kesukaran struktur kehidupan bakteria menyebabkan kebanyakan bakteria sukar dikultur. Saringan fungsi metagenomik dapat mengatasi kekangan saringan berasaskan kultur dalam meneroka dan menilai bahan genetik mikrob tidak kultur. Objektif kajian ini adalah bagi mengenal pasti klon protease aktif sejuk melalui saringan fungsi metagenomik. Kajian ini mencadangkan DNA alam sekitar (eDNA) yang diasingkan secara langsung dari tanah Antartika, dan dimasukkan ke dalam vektor fosmid pCC1FOS, ditransformasikan ke dalam sel hos EPI300-T1R E. coli, dan disaring untuk enzim proteolitik. Klon yang menghasilkan protease ini dikenal pasti dan diasingkan daripada agar susu skim. Agar telah ditambah dengan kloramfenikol dan arabinosa. Klon ini mengandungi fosmid pCC1FOS, di mana sisipan sebesar 48.5 kb telah disusun berturut-turut sepenuhnya dari kedua-dua arah. Analisis lanjut pada sisipan ini menunjukkan terdapat 70 NODE. NODE_42 mengandungi 297 asid amino protein hipotetis, iaitu sangat serasi dengan protein Peptidase M23 dan PG-binding 1. Model tiga dimensi protease yang diramalkan ini dihasilkan berdasarkan protease mesofilik Neisseria meningitides (PDB: 3SLU). Susunan struktur menunjukkan 27.07% persamaan nilai RMSD sebanyak 0.402 Å berdasarkan 58 sisa sejajar. Sisa tapak aktif kedua-duanya adalah sama, tetapi terdapat pemotongan besar telah berlaku dalam protease ramalan. Protease ini menunjukkan aktiviti enzim lebih tinggi pada suhu -20 °C dan 20 °C berbanding kawalan positif (protease dari pankreas lembu). Saringan fungsi metagenomik berhasil menemukan protease aktif sejuk berhomologi rendah terhadap susunan yang diketahui dan diekspresi dalam sel hos. Ia berpotensi bagi bioprospeksi dalam aplikasi bersuhu rendah
EXTENDABLE HIGH-GAIN DC-DC CONVERTER FOR STORAGE BATTERY AND PHOTOVOLTAIC CELL
Get PDFDC-DC converters with significant gain, ripple-free input current, and shared ground are required to elevate the output voltages of batteries, fuel cells, and Photovoltaic sources. The proposed topology utilizes a solitary switch to control the circuit and it has additional inculpation of a voltage doubler cell at the load side, a switch capacitor cell in the middle, and a quadratic cell at the output side. These cascaded configurations lead to significant voltage gains at moderate duty cycle rates. Additionally, the voltage stress over the power components is negligible, coming in under one-third of the resultant voltage. Moreover, the number of cells at the input and output side can be extended to obtain high voltage according to the requirements of the load. The gain in voltage, efficiency, and normalized voltage stress of the semiconductor elements in the circuit are examined concerning other solutions found in the literature. Eventually, photovoltaic and battery sources were included to analyze the proposed topology to confirm the circuit’s multifaceted functionality. The circuit was developed for 270 W, 440 V output from 36 V input, and a 40 kHz switching pulse was used to drive the switch. The theoretical and simulation analysis states that incorporating photovoltaic and other sources did not deteriorate the transformation efficiency. Simulink and PSIM analysis found that the circuit successfully transferred power from source to load.
ABSTRAK: Penukar DC-DC yang mempunyai gandaan ketara, input arus bebas riak dan pembumi berkongsi penting bagi meningkatkan voltan keluar bateri, sel bahan api dan sumber fotovolta. Topologi yang dicadangkan ini menggunakan suis tersendiri bagi mengawal litar dan ia mengandungi sel pendua voltan tambahan bagi menghentikan arus di bahagian beban, sel suis kapasitor di tengah dan sel kuadratik di bahagian voltan keluar. Konfigurasi berturutan ini membawa kepada gandaan voltan ketara pada kadar kitar tugas sederhana. Tambahan, tekanan voltan ke atas komponen kuasa boleh diabaikan, iaitu satu pertiga daripada voltan terhasil. Selain itu, bilangan sel di bahagian kemasukan dan keluaran arus boleh dilanjutkan bagi mendapatkan voltan tinggi mengikut keperluan beban. Gandaan voltan, kecekapan dan tekanan voltan ternormal pada bahan dalam litar semikonduktor diperiksa dengan menyamai penyelesaian lain yang ditemui dalam kajian terdahulu. Akhirnya, sumber fotovolta dan bateri dimasukkan bagi menganalisis topologi yang dicadangkan bagi mengesahkan fungsi pelbagai rupa litar. Litar yang dibangunkan ini digunakan pada kuasa 270 W, pada aras voltan 440 V dengan kemasukan voltan 36 V dan suis operasi berfrekuensi 40 kHz. Analisis teori dan simulasi menyatakan bahawa gabungan fotovolta dan sumber lain tidak mengurangkan kecekapan transformasi. Analisis Simulink dan PSIM mendapati litar ini berjaya memindahkan 95% kuasa dari sumber kepada beban
Effect of Incorporating Cellulose Nanofibers and Lemongrass Essential Oil in Polyvinyl Alcohol-Polyethylene Glycol/Glycerin Hydrogel for Wound Dressing
Get PDFHydrogels attract increased interest as wound dressings due to their biomimetic properties, creating a moist environment conducive to natural wound healing. In this study, a PVA-PEG/gly-CNF-LG hydrogel incorporating cellulose nanofibers (CNF) and lemongrass essential oil (LG) into the polyvinyl alcohol-polyethylene glycol/glycerin (PVA-PEG/gly) hydrogel via the freeze-thaw method was developed. The addition of CNFs and LG aimed to improve the physicochemical and antibacterial aspects of the hydrogel. Optimal hydrogel composition, determined through response surface methodology (RSM) and central composite design (CCD), consisted of 3.5% (w/v) CNFs and 3% (v/v) LG concentrations, resulting in an optimal moisture retention capability (MRC) of 37.69 ± 0.54%. The optimized PVA-PEG/gly-CNF-LG demonstrated impressive characteristics: a swelling capacity of 176.89 ± 1.56%, a gel fraction of 78.89 ± 0.42%, and a porosity of 47.51 ± 0.53%. FESEM images revealed the relatively porous nature of PVA-PEG/gly-CNF-LG hydrogels. Furthermore, the hydrogel exhibited excellent resistance against S. aureus and B. subtilis bacteria, along with notable tensile properties of 1.44 MPa. These findings underscore the promising attributes of the PVA-PEG/gly-CNF-LG hydrogel, positioning it as a versatile and effective wound-healing dressing with significant antimicrobial properties.
ABSTRAK: Hidrogel mendapat perhatian ramai sebagai pembalut luka di sebabkan oleh ciri-ciri biomimik, di mana menghasilkan persekitaran lembab yang baik bagi penyembuhan luka secara semula jadi. Kajian ini, mencadangkan hidrogel PVA-PEG/gly-CNF-LG yang mengandungi selulosa nanofiber (CNF) dan minyak pati serai (LG) dalam hidrogel polivenil alkohol-polietilin glikol/gliserin (PVA-PEG/gly) melalui kaedah beku-cair. Penambahan CNFs dan LG diperlukan bagi memperbaiki aspek fisiokimia dan antibakterial hidrogel. Komposisi optimal hidrogel, dibentuk melalui kaedah respons permukaan (RSM) dan reka bentuk komposit pusat (CCD), mengandungi 3.5% (w/v) CNFs dan 3% (v/v) kepekatan LG, menghasilkan kemampuan retensi kelembapan optimal (MRC) sebanyak 37.69 ± 0.54%. Kadar optimum PVA-PEG/gly-CNF-LG menunjukkan ciri-ciri yang menarik: iaitu kapasiti pembengkakan sebanyak 176.89 ± 1.56%, pecahan gel sebanyak 78.89 ± 0.42%, dan keliangan 47.51 ± 0.53%. Imej FESEM menunjukkan sifat keliangan semula jadi hidrogel PVA-PEG/gly-CNF-LG. Tambahan, hidrogel memiliki rintangan tinggi terhadap bakteria S. aureus dan B. subtilis, sejajar dengan ciri-ciri ketara tegangan 1.44 MPa. Dapatan kajian ini penting bagi ciri-ciri hidrogel yang berpotensi besar seperti PVA-PEG/gly-CNF-LG, menjadikannya serba guna dan berkesan sebagai balutan penyembuhan luka dengan ciri-ciri antimikrob yang ketara
Design and Development of a Slider-Crank Actuated Knee Exoskeleton with Optimized Motion Controller
Get PDFThe rising incidence of injuries and neurological disorders has highlighted the critical need for accessible and affordable rehabilitation solutions. In response to this demand, robotic exoskeletons have become a popular option for rehabilitation. However, current rehabilitation exoskeletons are generally expensive due to the high force of the actuators used, i.e., electric motors. Therefore, the availability is limited to patients who can afford to pay for physiotherapy using these robotic exoskeletons. Because of the demand for high force, the exoskeleton is heavy, impacting patient safety. In response to these challenges, the main contribution of this study is to develop a lightweight lower-body rehabilitation exoskeleton with sufficient force while maintaining a fast response time and precise motion control for rehabilitation purposes. In this research, a lower body knee joint rehabilitation exoskeleton prototype implementing a slider-crank mechanism was meticulously designed and optimized using Finite Element Analysis (FEA) via SolidWorks software. After optimising the design, the lower body exoskeleton (LBE) was fabricated and assembled. Next, the LBE system was characterized to understand its non-linear behaviour, as the LBE uses a double-acting pneumatic cylinder that is known to exhibit non-linear behaviour. To further analyse the effectiveness of LBE for rehabilitation, a Proportional-Integral-Derivative (PID) controller was adopted for its simplicity in controlling the exoskeleton's angular motions. Excellent results were obtained using a PID controller at the angular displacement of 75?, with a 96.5% reduction in overshoot (OS%), a 92.9% decrease in steady-state error (Ess), a 3.2% reduction of rise time (Tr), and a minimal 0.006% reduction in settling time (Ts). These findings indicate that the LBE with the slider-crank mechanism is a promising device, particularly for knee joint rehabilitation, and that it can be applied to other rehabilitation applications that require a lightweight design and high force application.
ABSTRAK: Peningkatan kecederaan dan gangguan neurologi menyebabkan keperluan kritikal terhadap pemulihan yang senang diakses dan berpatutan. Sebagai solusi kepada keperluan ini, robot eksoskleton telah menjadi pilihan popular bagi sesi pemulihan. Namun, eksoskleton pemulihan sedia ada adalah secara amnya mahal kerana memerlukan daya penggerak yang tinggi, contohnya motor elektrik. Maka, ketersediaan menggunakan eksoskleton pemulihan ini terhad kepada pesakit yang mampu membayar fisioterapi mahal menggunakan robot eksoskleton. Selain itu, disebabkan permintaan pada daya penggerak tinggi, robot eksoskleton secara tidak langsung adalah berat dan ini akan memberi kesan kepada keselamatan pesakit. Sebagai solusi kepada permasalahan ini, sumbangan utama kajian ini adalah bagi membangunkan eksoskleton pemulihan bahagian bawah badan yang ringan dan mempunyai daya penggerak yang mencukupi, di samping mengekalkan masa tindak balas yang cepat dan kawalan pergerakan yang tepat bagi tujuan pemulihan. Penyelidikan ini membangunkan prototaip eksoskleton pemulihan sendi lutut bawah badan (LBE) yang menggunakan mekanisme engkol gelangsar dan dioptimumkan dengan teliti menggunakan Analisis Unsur Terhingga (FEA), menggunakan perisian SolidWorks. Selepas reka bentuk dioptimumkan, eksoskleton LBE telah difabrikasi dan dipasang. Seterusnya sistem LBE telah direka bagi memahami ciri-ciri tidak linear, kerana sistem LBE ini menggunakan silinder pneumatik dwitindakan, dimana pneumatik terkenal sebagai sistem tidak linear. Bagi menganalisa lebih lanjut keberkesanan LBE sebagai sistem pemulihan, kawalan Berkadaran-Kamiran-Pembeza (PID) telah digunakan bagi memudahkan kawalan sudut gerakan eksoskleton. Dapatan kajian menunjukkan, kawalan PID adalah sangat baik pada gerakan sudut maksimum, anjakan sudut 75?, di mana pengurangan 96.5% yang ketara dalam lajakan (OS%), penurunan 92.9% dalam ralat keadaan mantap (Ess), 3.2% pengurangan masa naik (Tr), dan pengurangan minimum 0.006% dalam masa penetapan (Ts). Penemuan ini menunjukkan bahawa sistem LBE dengan menggunakan mekanisme engkol gelangsar adalah peralatan yang berkesan, terutama bagi pemulihan sendi lutut, dan ia juga boleh digunakan bagi aplikasi pemulihan lain yang memerlukan reka bentuk ringan dan aplikasi daya yang tinggi
EFFECTS OF SOIL ERODIBILITY ON RIVERBANK EROSION AND FAILURES
Get PDFRiverbank erosion is a natural process of removal of earthen materials from the bank surface. The process of riverbank erosion that is induced naturally results in the formation of landforms such as valleys, canyons, and productive floodplains. However, riverbank erosion can also be considered a hazard when the process occurs at an alarming rate causing loss of land. The extent of erosion depends on many factors. One of the main factors responsible for riverbank erosion is the soil erodibility which is the resistance of soil to erosion. The aim of this study is to quantify the riverbank erosion rates and the potential magnitude of riverbank erosion in order to generate an empirical predictive model to estimate riverbank erosion from physical and geomorphic variables for rivers susceptible to riverbank erosion. Several models were trained using the Regression Learner application in MATLAB software. Models that include soil erodibility parameters perform better than the models without the soil erodibility parameters. The model with the highest accuracy was found to be Model 2, with Root Mean Square Error (RMSE) of 3.70E-08 and coefficient of determination, R2 of 0.55. The model produced in this study will be helpful to analyze and predict the effects of riverbank erosion and assist in the development of bank stabilization solution.
ABSTRAK: Hakisan tebing sungai adalah proses semula jadi terhadap penyingkiran bahan tanah dari permukaan tebing. Proses hakisan tebing sungai yang terjadi secara semula jadi ini mengakibatkan pembentukan bentuk muka bumi seperti lembah, ngarai dan dataran banjir yang produktif. Bagaimanapun, hakisan tebing sungai juga boleh dianggap sebagai ancaman apabila proses berlaku pada kadar membimbangkan sehingga menyebabkan kehilangan tanah. Tahap hakisan bergantung pada banyak faktor. Salah satu faktor utama yang menyebabkan hakisan tebing sungai adalah kebolehhakisan tanah iaitu ketahanan tanah terhadap hakisan. Kajian ini bertujuan untuk mengukur kadar hakisan tebing sungai, mengkaji potensi magnitud hakisan tebing sungai dan menghasilkan model ramalan empirik bagi menganggarkan hakisan tebing sungai daripada pembolehubah fizikal dan geomorfik bagi sungai yang terdedah kepada hakisan tebing sungai. Beberapa model telah dilatih menggunakan aplikasi Regression Learner dalam perisian MATLAB. Dapatan menunjukkan model yang mengandungi parameter kebolehhakisan tanah adalah lebih baik berbanding model tanpa parameter kebolehhakisan tanah. Model 2 didapati mempunyai ketepatan tertinggi dengan ralat punca min kuasa dua (RMSE) sebanyak 3.70E-08 dan pekali penentuan, R2 sebanyak 0.55. Model dalam kajian ini dapat membantu dalam analisa berkaitan kesan hakisan tebing sungai dan penyelesaian kepada pembangunan kestabilan tebing
Performance Analysis of an Induction Motor Coupled VIF with MR Fluid Damper
Get PDFThe flywheel is a classic mechanical device that is often used to enhance the rotational motion of engines. Electrical machines often face fluctuations in speed that hamper speed stability and cause extra power consumption. Recently, a few publications have analyzed the impact of the flywheel to reduce fluctuation and energy consumption in electric motors. This study proposes the use of a flywheel with a changeable moment of inertia, which can be manipulated to boost both speed stability and energy efficiency. The objective is to improve the speed stability of industrial motors in the presence of the loading effect. This study introduces a magneto-rheological variable inertia flywheel (MRVIF) to control rotational speed and reduce power usage. The purpose of analytical development is to assess the influence of rotational speed and excitation current on the MR damper's moment of inertia for control purposes. The investigation focuses on the analysis of power usage and stability across different power inputs and rotating speeds. The effectiveness of the suggested MRVIF was evaluated via the development of a prototype. Experiments were undertaken to validate the effectiveness and stability of the system. The findings illustrate the potential use of MRVIF in reducing energy consumption and enhancing speed stability.
ABSTRAK: ‘Flywheel’ atau roda tenaga adalah peranti mekanikal klasik yang sering digunakan bagi meningkatkan gerakan putaran enjin. Mesin elektrik sering menghadapi turun naik kelajuan yang menghalang kestabilan kelajuan dan menyebabkan penggunaan kuasa tambahan. Baru-baru ini, terdapat beberapa kajian terdahulu yang menganalisis kesan roda tenaga bagi mengurangkan turun naik dan penggunaan tenaga dalam motor elektrik. Kajian ini mencadangkan penggunaan roda tenaga dengan momen inersia boleh ubah, di mana ia boleh dimanipulasi bagi meningkatkan kestabilan kelajuan dan kecekapan tenaga. Objektif kajian adalah bagi meningkatkan kestabilan kelajuan motor industri bersama kesan muatan. Kajian ini memperkenalkan pembolehubah magnetorheologikal roda tenaga inersia (MRVIF) bagi mengawal kelajuan putaran dan mengurangkan penggunaan kuasa. Tujuan pembangunan analitikal ini adalah bagi menilai pengaruh kelajuan putaran dan arus pengujaan pada momen inersia peredam MR bagi tujuan kawalan. Kajian memfokuskan pada analisis penggunaan kuasa dan kestabilan merentas pelbagai input kuasa dan kelajuan putaran. Keberkesanan MRVIF yang dicadangkan telah diuji melalui pembangunan prototaip. Eksperimen dijalankan bagi mengesahkan keberkesanan dan kestabilan sistem. Penemuan ini menggambarkan potensi MRVIF dalam mengurangkan penggunaan tenaga dan meningkatkan kestabilan kelajuan
Building a GIS Map for Forecasting the MIR Index in An Giang
Get PDFThe MIR aquatic plant signal is capable of predicting specific pollution sources of water, contributing significantly to the effective management of surface water resources in An Giang province. The use of aquatic plants in water pollution treatment brings about positive effects through natural self-purification processes as they consume organic and nutrient substances such as N and P. Therefore, it is crucial to develop a tool for monitoring and supervising aquatic plant species. This paper investigates the application of GIS technology to build a GIS map representing the current status of vegetation cover in An Giang province. The background layers of the GIS database, along with detailed attribute layers regarding species composition, dominant species, and vegetation area, will serve as the basis for managing, utilizing, conserving, and restoring vegetation cover in the research area. Additionally, a predictive model for MIR indices has been constructed using machine learning methods. The results indicate that the model has a coefficient of determination (R2) of 91.7% for the dependent variable MIR compared to the independent variables. Subsequently, these results are visually displayed on a GIS map at 18 monitoring points within An Giang province, enabling users to easily observe, compare, evaluate, and propose suitable solutions for surface water quality management.
ABSTRAK: Isyarat tumbuhan akuatik MIR mampu meramalkan sumber pencemaran air secara spesifik, iaitu penyumbang penting kepada pengurusan berkesan permukaan sumber air di wilayah An Giang. Penggunaan tumbuhan akuatik dalam rawatan pencemaran membawa kepada kesan positif melalui proses rawatan kendiri secara semula jadi kerana ia mengandungi bahan organik dan nutrien seperti N dan P. Oleh itu, sangat penting bagi membangunkan alat pemantauan dan pengawasan spesies tumbuhan akuatik. Kajian ini mengkaji aplikasi teknologi GIS bagi membangunkan peta GIS mewakili status terkini keseluruhan tumbuhan di wilayah An Giang. Lapisan latar belakang pangkalan data GIS bersama lapisan sifat-sifat terperinci berkenaan spesies komposit, spesies dominan, dan kawasan tumbuh-tumbuhan, dapat menyediakan asas kepada pengurusan, penggunaan, pemuliharaan, dan pemulihan tumbuh-tumbuhan meliputi kawasan kajian. Tambahan, model ramalan MIR dibangunkan menggunakan kaedah pembelajaran mesin. Dapatan kajian menunjukkan model ini mempunyai pekali penentu (R2) sebanyak 91.7% bagi pembolehubah MIR bersandar berbanding pembolehubah tak bersandar. Menyebabkan dapatan ini secara visual dapat dilihat pada peta GIS menggunakan 18 titik pantauan dalam wilayah An Giang province, membolehkan pengguna mudah melihat, membandingkan, menilai, dan mencadangkan solusi sesuai bagi pengurusan kualiti permukaan air
INFLUENCE OF CURING CONDITIONS ON THE EARLY STRENGTH OF LOW TEMPERATURE BELITE CEMENTS
Get PDFLow temperature belite cements are produced using techniques that stabilize the more reactive high temperature polymorphs of dicalcium silicate (C2S) to improve early strength, but the effect of curing conditions on them is not well studied. The focus of this work is to assess the improvement of their early strength in different curing conditions. During the synthesis of the cements at 1000 ºC, the more reactive polymorphs, -C2S and ?-C2S, were stabilized using gypsum and hydrothermal treatment with potassium hydroxide. The phase composition of the synthesized cements was analysed using X-ray powder diffraction. The morphology and elemental composition of the C2S crystals and hydrated pastes was determined using a scanning electron microscope equipped with an energy-dispersive X-ray system. Mortar samples were cured in different conditions that include hot air and hot water curing at 60 ºC and 90 ºC. The 28-day strength development, capillary water porosity, water absorption, and ultrasonic pulse velocity were tested. The formation of hydration products and strength was dependent on the type of C2S polymorph. Curing at elevated temperatures improved the transport properties of mortars. Samples cured at 90 ºC in hot air obtained the highest early strength. The presence of -C2S and elevated curing temperatures significantly improve the early strength of the mortar samples.
ABSTRAK: Simen belite suhu rendah dihasilkan melalui teknik menstabilkan reaktif polimof dikalsium silikat (C2S) bersuhu tinggi bagi meningkatkan kekuatan awal, tetapi kesan keadaan pengawetan ke atasnya tidak dikaji dengan baik. Fokus kerja ini adalah bagi menilai peningkatan kekuatan awal pada keadaan pengawetan berbeza. Sintesis simen pada suhu 1000 ºC, iaitu pada polimof lebih reaktif, -C2S dan ?-C2S, telah distabilkan menggunakan rawatan gipsum dan hidroterma dengan kalium hidroksida. Fasa komposisi simen tersintesis dianalisa menggunakan pembelauan serbuk sinar-X. Komposisi morfologi dan unsur kristal C2S dan pes terhidrat ditentukan menggunakan pengimbas mikroskop elektron yang dilengkapi sistem sinar-X penyebar tenaga. Sampel mortar telah diawetkan dalam keadaan berbeza termasuk pengawetan udara panas dan air panas pada suhu 60 ºC dan 90 ºC. Perkembangan kekuatan keliangan kapilari air, penyerapan air, dan halaju nadi ultrasonik telah diuji pada hari ke 28. Pembentukan produk penghidratan dan kekuatan adalah bergantung kepada jenis polimof C2S. Pengawetan pada suhu tinggi meningkatkan sifat pengangkutan mortar. Sampel yang diawet pada 90 ºC dalam udara panas memperoleh kekuatan awal tertinggi. Kehadiran -C2S dan suhu pengawetan tinggi dengan ketara meningkatkan kekuatan awal sampel mortar
Operational Cost Models for an Earth Station System Using 2-Parallel and 4-Parallel Configurations
Get PDFOperational cost is important in any system. In the case of the earth station system, operational cost is very crucial. The operational cost can be divided into three costs: maintenance, failure, and replacement costs. There are many complex subsystems incorporated in the earth station system, for instance a high-power amplifier, modulators, and antennas, to name a few. In this research, only the replacement cost was considered. Moreover, there are many replacement methods that are available. These replacement methods implicitly influence both the replacement and the replacement costs. The aim of this research is to provide a new cost model based on which replacement method yields the lowest cost. Two replacement methods are involved in this research: failure-triggered and age-based. The failure-triggered and the age-based replacement methods were considered because these methods are the most used in previous research work. Furthermore, three types of cost models were also considered, and they were linear, polynomial, and exponential operational cost models. The outcomes show that the failure-triggered and age-based replacement methods of 2-parallel configuration of polynomial and linear operational cost models yielded the lowest RMSE value of 2.5. Therefore, both polynomial and linear operational cost models of the 2-parallel configuration were the most optimal operational cost models.
ABSTRAK: Kos operasi adalah penting dalam mana-mana sistem. Dalam kes sistem stesen bumi, kos operasi adalah sangat penting. Kos operasi boleh dibahagikan kepada tiga kos: kos penyelenggaraan, kegagalan dan penggantian. Terdapat banyak subsistem kompleks yang digabungkan dalam sistem stesen bumi, contohnya penguat kuasa tinggi, modulator, dan antena. Penyelidikan ini hanya membincangkan tentang kos penggantian. Selain itu, terdapat banyak kaedah penggantian sedia ada. Kaedah penggantian ini secara tersirat mempengaruhi kedua-dua kos penggantian dan penggantian. Matlamat penyelidikan ini adalah bagi menyediakan model kos baharu berdasarkan kaedah penggantian yang menghasilkan kos terendah. Dua kaedah penggantian yang terlibat dalam kajian ini: penggantian yang dicetuskan oleh kegagalan dan berdasarkan umur. Kaedah cetusan kegagalan dan penggantian berasaskan umur telah dipertimbangkan kerana kaedah ini paling banyak digunakan dalam penyelidikan terdahulu. Tambahan, tiga jenis model kos turut dipertimbangkan, iaitu model kos operasi linear, polinomial dan eksponen. Dapatan menunjukkan kaedah penggantian cetusan kegagalan dan berdasarkan umur melalui konfigurasi model 2 selari bagi kos operasi polinomial dan linear menghasilkan nilai RMSE terendah iaitu 2.5. Oleh itu, kedua-dua model kos operasi polinomial dan linear bagi konfigurasi model 2 selari adalah kos operasi paling optimum