Mechanical Engineering Commons^™

Effects Of The Preheating Temperature On The Crystal Structure And Texture Of Martensitic Stainless Steel, Tri Hardi Priyanto, Rifai Muslih, Herry Mugirahardjo, Bharoto Bharoto, Andon Insani, Muzzakiy Muzzakiy

Makara Journal of Technology

Theoretically, the preheating temperature refers to the start martensite temperature (Ms), and the martensite transformation can be considered as the conservation of the invariant habit-plane in the lattice structure. The habit-plane is the interface plane between austenite and martensite as measured on a macroscopic scale. From the calculation, Ms = 252 °C. The martensite formation can be affected by temperature or stress treatment. In this experiment, temperature treatment was conducted. The sample was treated at 250 °C ± 10 °C. Before and after the pre-heat treatment, the sample was characterized using the neutron diffraction method. BATAN’s Texture Diffractometer (DN2) with …

Investigation Of Ship Hull Girder Strength With Grounding Damage, Muhammad Zubair Muis Alie, Ristiyanto Adiputra

Makara Journal of Technology

The objective of the present study is to investigate ship hull girder strength as a result of grounding damage upon longitudinal bending. A bulk carrier and tanker are analyzed and Smith’s Method is adopted and implemented in the analysis program. An efficient solution procedure is performed by assuming the cross-section remains plane and the vertical bending moment is applied to the cross section. As a fundamental case, the damage is simply created by removing the elements from the cross section. Welding residual stress, initial imperfections, and crack extensions are not considered. The grounding damage is made by two conditions, namely …

Satellite-Based Monitoring Of Spatiotemporal Changes In Batudulang Forest In Sumbawa, Indonesia, Mohammad Muslim, Arief Budhi Witarto, Wahyu Indrajaya

Makara Journal of Technology

Space-based earth observation technology applicable to forest inventory and monitoring is well known in the scientific community. High-resolution satellite images form an important data source for forest mapping and change detection at regional and national scales. The value of forest change information derived from remote sensing data is significantly enhanced if this information is integrated into a spatially explicit geographic information system. Satellite-based rapid assessment was conducted to measure spatiotemporal changes in Batudulang forest over the years. The general approach to quantify change in the spatial aspect of the forest involved change detection using moderate-resolution imaging spectro-radiometer satellite-based normalized difference …

Strength Structure Analysis Of Main Gate Graving Dock Using Pontoons For Condition Repairs, Budianto Budianto

Makara Journal of Technology

Main gate graving dock with pontoon type can certainly suffered some level of damage after a long period of operation. Many employments within the graving dock can delay the process repair of main gate. The main gate may not be opened, because employees are still working to ship fabrication process under sea waterline. For accommodate these interrelated conditions, the best solution with repair one side of the main gate with type pontoon and employees can still work ship fabrication process in graving dock conducted simultaneously. The repair process conditions must be required main gate structure that consists of only one …

Microstructures And Hardness Of Tig Welded Experimental 57fe15cr25ni Steel, Parikin Parikin, Mohammad Dani, Abu Khalid Rivai, Agus Hadi Ismoyo, Riza Iskandar, Arbi Dimyati

Makara Journal of Technology

The microstructures and hardness of tungsten inert gas (TIG) welded experimental 57Fe15Cr25Ni steel were investigated through optical–scanning electron microscopy analyses and with a hardness tester, respectively. The welding process restructured the constituent atoms into regular and irregular crystal lattices. Rapid cooling of the weld metal allowed the formation of a dendritic (columnar) structure, with porous grains. By contrast, slow cooling influenced HAZ and led to the formation of grain structures. The crystal lattice became more organized and larger than other zones. Meanwhile, the base metal formed circular nets that covered large area inside thick and thin grain boundaries. The diffraction …

Mapping Of Bruise Of Oil Palm Fresh Fruit Bunch During Loading And Transportation From Field To Mill, Andreas Wahyu Krisdiarto

Makara Journal of Technology

Fresh fruit bunches (FFBs) are used as raw materials for palm oil, and their transport from a field is a critical step to maintain their quality. Fruit integrity should be maintained so the mill can efficiently obtain palm oil with less than 5% free fatty acid content. Physical treatments for FFBs during loading to truck bins and transport may cause physical injuries. This research aimed to map fruit bruises. The map can be used as a basis in managing transport of FFBs. Physical injuries were assessed by bruise index (BI), which was calculated by measuring the bruise area and weight …

Benchmarking Product Service System Of Generator Set Distributors, Venny Violetta Tiurindah, Tanika Dewi Sofianti

Makara Journal of Technology

Power generation is an industry that is essential to sustain daily life and competes with generator set distributors. The product service system of distributors must be improved to survive the competition. This research aims to develop tools for benchmarking the product service system of generator set distributors. Benchmarking identifies gaps between a product and other competitors’ products. In this work, a product service system board is used to visualize the current product service system of a generator set distributor. A PPIAF framework and a SERVQUAL framework are adapted to assess product performance and service quality, respectively. AHP is used as …

Improving Seaglider Efficiency: An Analysis Of Wing Shapes, Hull Morphologies, And Propulsion Methods, Christopher James Hockley

Doctoral Dissertations and Master's Theses

Autonomous underwater gliders are a family of autonomous underwater vehicles used for long-term observation of oceanic environments. These gliders leverage changes in buoyancy and the resulting vertical motion, to generate forward locomotion via hydrodynamic surfaces. In order to function for extended periods, these systems operate in a low-speed, low-drag regime. This research examines factors impacting the operational efficiencies of gliders, including morphological changes, configuration changes, and propulsion. An interesting question arises when considering the operational efficiencies of conventionally propelled systems at the operating speeds typical of gliders. Can a conventional propulsion system match the efficiency of an underwater glider buoyancy …

A Quantitative Analysis Of Shape Characteristics Of Marine Snow Particles With Interactive Visualization: Validation Of Assumptions In Coagulation Models, Palak P. Dave

USF Tampa Graduate Theses and Dissertations

The Deepwater Horizon oil spill that started on April 20, 2010, in the Gulf of Mexico was the largest marine oil spill in the history of the petroleum industry. There was an unexpected and prolonged sedimentation event of oil-associated marine snow to the seafloor due to the oil spill. The sedimentation event occurred because of the coagulation process among oil associated marine particles. Marine scientists are developing models for the coagulation process of marine particles and oil, in order to estimate the amount of oil that may reach the seafloor along with marine particles. These models, used certain assumptions regarding …

Purple Urchin Removal, Cullen Goss, Wil Gilbreath, Kevin Marshall

Mechanical Engineering

Soaring purple urchin populations have contributed to a greater than 90% reduction of northern California’s bull kelp forests. Human intervention to reduce the purple urchin population may allow localized kelp patches to grow. The California Department of Fish and Wildlife requested that our team develop a mechanical device to aid in the removal of the urchins. This document provides an update from the scope of work and details the process conducted to reach a scale final design. In this document, we provide background research to show our understanding of urchins and their effect on kelp forests. Then, we analyze the …

Risk Assessment Of Dropped Cylindrical Objects In Offshore Operations, Adelina Steven

LSU New Orleans Theses and Dissertations

Dropped object are defined as any object that fall under its own weight from a previously static position or fell due to an applied force from equipment or a moving object. It is among the top ten causes of injuries and fatality in oil and gas industry. To solve this problem, several in-house tools and guidelines is developed over time to assess the risk of dropped objects on the sub-sea structures. This thesis focuses on compiling and comparing those methods in hope to improve the recommended practices available in the market. A simple modification is done on the in-house tools …

Cfd Analysis Of Resistance For Stepless And Stepped Planing Hulls, Bhanu Prakash Valtheru

Theses and Dissertations

It is the endeavour of naval architects to design hull forms with the least amount of power consumption. In this respect, Naval Architects have been obsessed with the design of various hull forms optimized for a particular service requiring the lowest amount of fuel consumption keeping in mind effects on the climate change and sustainability. Regardless of the way that a considerable measure of research has been done around this area, there remains a level of uncertainty in the reasonably accurate resistance prediction of stepped hull forms in the early design stage. Model tests and full-scale tests are still the …

An Underwater Vehicle Navigation System Using Acoustic And Inertial Sensors, Khalid M. Alzahrani

Doctoral Dissertations and Master's Theses

Unmanned Underwater Vehicles (UUVs) have become an essential tool for different underwater tasks. Compared with other unmanned systems, the navigation and localization for UUVs are particularly challenging due to the unavailability of Global Positioning System (GPS) signals underwater and the complexity of the unstable environment. Alternative methods such as acoustic positioning systems, Inertial Navigation Systems (INS), and the geophysical navigation approach are used for UUV navigation. Acoustic positioning systems utilize the characteristics of acoustic signals that have a lower absorption rate and a more extended propagation distance than electromagnetic signals underwater. The significant disadvantage of the INS is the “drift,” …

Hawai'i Wildlife Fund V. County Of Maui, Lowell J. Chandler

Public Land & Resources Law Review

In Hawai’i Wildlife Fund v. County of Maui, the Ninth Circuit held that the plain language of the Clean Water Act provides jurisdiction over indirect discharges of pollutants from a point source into groundwater that is shown to be connected to navigable waters. The court found that studies confirmed pollutants entering the Pacific Ocean were fairly traceable to the County of Maui’s sewage disposal wells. In affirming the district court’s ruling, the Ninth Circuit held that Maui County violated the Clean Water Act by discharging pollutants into a navigable water without the required permit. The court also concluded the …

Controlled Intake Area Dredging For Fine Sediment Removal To Improve Water Quality In The Indian River Lagoon, Hannah Christine Grisanti

Theses and Dissertations

This study is an investigation of hydraulic dredging specifically designed to remove muck and other fine sediments from local water systems in Brevard County, Florida. The goal of the project is to improve water quality in the Indian River Lagoon (IRL) and create positive environmental impacts. Dredging is an excavation activity that takes place underwater in shallow seas or freshwater environments to remove material from the bottom surface. Typically, dredging techniques are implemented to keep waterways such as canals, inlets, and harbors navigable for boats and barges. Dredging is also commonly used to move sand from offshore sources to beaches …

Structural And Photoluminescence Properties Of Zno Thin Films Deposited By Ultrasonic Spray Pyrolysis, Iwan Sugihartono, Erfan Handoko, Vivi Fauzia, Artoto Arkundato, Lara Permata Sari

Makara Journal of Technology

Zinc oxide (ZnO) thin films on a silicon (Si) (111) substrate were grown herein using ultrasonic spray pyrolysis at 450 °C with different Zn concentrations. The ZnO thin films had X-ray diffraction patterns of a polycrystalline hexagonal wurtzite structure. The (002) and (101) peak intensities changed under different Zn concentrations. Furthermore, according to Scherer's and Stokes–Wilson equations, the crystallite size and the internal strain of the ZnO thin films in the (002) and (101) peaks changed with the Zn concentration. Optically, the photoluminescence spectra indicated that the ratio of the UV/GB emission of the ZnO thin films was the highest …

An Exploratory Study Of Sukuk Utilisation For Transportation Infrastructure Development In Indonesia, Fiona Lamari, Ayomi Dita Rarasati, Meilia Evita

Makara Journal of Technology

Investment in infrastructure is one of the principal drivers of the growth of the economy. For that reason, the Indonesian government has proposed an investment budget in the railway and sea and air transport sectors over the next 10 years. In order to overcome the burden of direct outflows and for the future, a study was conducted to lay down the framework of Shariah-compliant payments for the development of infrastructure in Indonesia in the transport sector. This paper aims to explore the opportunity and implementation of sukuk utilisation to develop transportation infrastructure. Secondary data study and interviews were selected for …

Small-Signal-Stability Enhancement Using A Power-System Stabilizer Based On The Cuckoo-Search Algorithm Against Contingency N-1 In The Sulselrabar 150-Kv System, Muhammad Ruswandi Djalal, Muhammad Yusuf Yunus, Herlambang Setiadi, Awan Uji Krismanto

Makara Journal of Technology

Small-signal stability is one of the main factors limiting power transmission in conventional power systems. This concern is primarily handled by adding damper windings of a synchronous generator and power-system stabilizer (PSS). However, due to the impact of the N-1 contingency, damper windings and a conventional PSS are insufficient to overcome this problem. Proper placement and design of the PSS are crucial for improving stability. One approach to optimizing the placement and tuning of the PSS is to use an artificial-intelligence method. Here, the cuckoo-search algorithm (CSA) is proposed to optimize the PSS tuning and placement. Based on simulation, it …

Isolation And Molecular Weight Characterization Of Tetragonula Laeviceps Honey Protein, Muhamad Sahlan, Nurul Azizah, Kazuaki Hakamada, Keiichi Noguchi, Masafumi Yohda

Makara Journal of Technology

The concentration of protein in honey is lower than polysaccharide. However, recently the honey’s protein is intensively studied and it showed that protein also have several biological activities such as antibacterial activity. The purpose of this research is to isolate and characterize Tetragonula laeviceps honey protein by determining the molecular weight. Honey protein of Trigona laeviceps was isolated using ultra-filtration with the membrane’s size of 30 kDa, then concentrated using tube membrane size 10 kDa. Molecular weight was analyzed by SDS PAGE. From the analysis, there was major protein band in honey produced by Tetragona laeviceps identified. The produced molecular …

Prerequisites For Public Acceptance Of Waste-To-Energy Plants: Evidence From Germany And Indonesia, Uwe Lahl, Barbara Zeschmar-Lahl

Makara Journal of Technology

Construction of waste incinerators often encounters resistance from the public. The minimum requirements for the ac- ceptance of these installations include modern air pollution control (APC) technology and safe disposal of residues. Confidence in the statements of government and government agencies as well as on those who support is an important point of acceptance. Independent scientific bodies such as universities can help to make this happen. In the case of the installation of waste into energy (WtE), such scientific support can be the measurement of emissions and their evalua- tion. Many products that enter the waste stream contain heavy metals, …

Hybrid Brain-Computer Interface: A Novel Method On The Integration Of Eeg And Semg Signal For Active Prosthetic Control, Reza Darmakusuma, Ary Setijadi Prihatmanto, Adi Indrayanto, Tati Latifah Mengko

Makara Journal of Technology

This paper describes a novel method for controlling active prosthetics by integrating surface electromyography (sEMG) and electroencephalograph signals to improve its intuitiveness. This paper also compares the new method (RTA-2) with other existing methods (AND and OR) for controlling active prosthetics. Based on analysis, RTA-2 features higher true positive rate (TPR) and balanced accuracy (BA) than AND method. On the other hand, the new method (RTA-2) yields lower false detection rate (FPR) than OR method. Analysis also shows that RTA-2 possesses equal TPR, FPR, and BA with the detection of movement intention using sEMG-based system. Although the RTA-2 method shows …

Seismic Response Analysis Along The Coastal Area Of Bengkulu During The September 2007 Earthquake, Lindung Zalbuin Mase

Makara Journal of Technology

A strong earthquake of 8.4 Mw occurred at the Sumatra Subduction Zone in September 12, 2007. The area that underwent the impact of the earthquake was located along the coastal area of the Bengkulu Province. A seismic ground response study was then performed with reference to the event. Several site investigations, including standard penetration test and shear wave velocity tests, were conducted to understand the subsoil condition. The data were used to analyze a ground response during the earthquake. The amplification factor of each site was obtained, and a comparison of the spectral accelerations was performed. The results showed that …

Coax-Fed Dipole-Type Applicator For Hepatic Cancer Rf Ablation, Basari Basari, Aditya Rakhmadi, Kazuyuki Saito

Makara Journal of Technology

Cancer is the third leading cause of mortality in the world and is one of the most difficult diseases to detect and cure. This fact motivates us to investigate a treatment method by using radiofrequency (RF) ablation. RF ablation therapy kills cancer cells by electromagnetically heating them up. The treatment uses an applicator that is inserted into the body to heat the cells. The cancer cells are exposed to a temperature of more than 60 °C in short duration (a few seconds to a few minutes), thereby causing cell destruction locally. To ensure effective treatment, a minimally invasive method is …

Geometric Optimization Of A Heaving Point Absorber Wave Energy Converter, Ian Riley

College of Graduate Studies: Theses & Dissertations

Wave energy shows significant potential for development into a competitive renewable energy source. Non-renewable resources are finite and contribute to adverse effects on the environment. Development of wave energy conversion devices that use heave motion as the primary driver for converting wave energy into electrical potential is explored through optimizing the geometry of an axisymmetric partially submerged buoy in deep water. The governing equations of motion and hydrodynamic forces are solved for in one degree of freedom using ANSYS Aqwa. An external PTO device is simulated to induce power capture in the system. Four different geometric shapes are tested and …

Extending Maneuverability Of Internally Actuated Underwater Gliders, An Attempt To Develop An Open Platform For Research And Education, Saeedeh Ziaeefard

Dissertations, Master's Theses and Master's Reports

Increasing maneuverability of internally actuated Underwater Gliders (UGs) is inevitable due to high demands in underwater surveillance and reconnaissance missions where agility and stealthiness are the keys to success. High maneuverability is needed to provide the opportunity for optimal trajectory planning, planar motion smoothness, and re-planning adapting to the dynamic environments.

This work explores extending the maneuverability of underwater gliders through coupled improvement in mechanical design, efficient use of internal actuation, and motion planning strategy utilizing flight concatenation. The existence of five flight patterns ``advanced flight", inspired by air gliders, enabled solely by utilizing internal actuation are investigated: Circle, Oval …

Optimal Control Of Wave Energy Converters, Shangyan Zou

Dissertations, Master's Theses and Master's Reports

In this dissertation, we address the optimal control of the Wave Energy Converters. The Wave Energy Converters introduced in this study can be categorized as the single body heaving device, the single body pitching device, the single body three degrees of freedoms device, and the Wave Energy Converters array. Different types of Wave Energy Converters are modeled mathematically, and different optimal controls are developed for them. The objective of the optimal controllers is to maximize the energy extraction with and without the motion and control constraints. The development of the unconstrained control is first introduced which includes the implementation of …

Optimization And Control Of An Array Of Wave Energy Converters, Jianyang Lyu

Dissertations, Master's Theses and Master's Reports

This study explored optimal configuration of both the array layout and the dimension of each WEC in the array. The array contains heaving buoys with full interaction and exact hydrodynamics. Optimization of dimension was done on each WEC in the array with a given optimal layout, and a higher q-factor was achieved. Both impedance matching optimal control and derivative control were employed, which provides both theoretical maximum energy and a more realistic case. Then the work was expanded to optimization of both the array layout and the dimension of each WEC in the array. An average of 39.21% higher q-factor …

Potential Replacement Of The Us Navy's Rapid Penetration Test With The Method Of Multichannel Analysis Of Surface Waves, William Fletcher

UNF Graduate Theses and Dissertations

The United States Navy (USN) currently utilizes a Rapid Penetration Test (RPT) on both land and in water as the means to determine whether sufficient soil bearing capacity exists for piles in axial compression, prior to construction of the Elevated Causeway System (Modular) [ELCAS(M)] pile-supported pier system. The USN desires a replacement for the RPT because of issues with the method incorrectly classifying soils as well as the need to have a less labor-and-equipment-intensive method for geotechnical investigation.

The Multichannel Analysis of Surface Waves (MASW) method is selected herein as the potential replacement for the RPT. The MASW method is …

An Integrated Closed Convergent System For Optimal Extraction Of Head-Driven Tidal Energy, Michelle Ann Vieira

UNF Graduate Theses and Dissertations

As the demands for energy increased with the global increase in population, there is a need to create and invest in more clean and renewable energy sources. Energy derived from the movement of the tides is an ancient concept that is currently being harnessed in a handful of large tidal range locations. However, the need to move from fossil fuel driven energy sources to those that are clean and non-polluting is a priority for a sustainable future. Globally, hydropower potential is estimated to be more than 16,400-Terawatt hours annually. Given that the electricity consumption worldwide was at 15,068-Terawatt hours in …

Energy Potentials Of Briquette Produced From Tannery Solid Waste, Olatunde Ajani Oyelaran, Faralu Muhammed Sani, Olawale Monsur Sanusi, Olusegun Balogun, Adeyinka Okeowo Fagbemigun

Makara Journal of Technology

The vast quantity of waste generated from industries is one of the serious outcomes of unplanned development, resulting into quantum of hazardous organic and inorganic waste generating daily. Proper waste management is a challenging issue that must be addressed adequately. This is, therefore, carried out with a view of assessing the energy and combustion quality of tannery solid waste with a view of converting them into briquettes for cooking, heating and small home industries and reducing the menace caused by tannery waste disposal. The results of the experiments showed that the combustion rate ranged between 0.171 and 0.217 g/min, the …