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Journal of Marine Science and Technology–Taiwan

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Full-Text Articles in Engineering

Optimal Design On One-Layer Close-Fitting Acoustical Hoods Using A Simulated Annealing Method, Min-Chie Chiu Apr 2014

Optimal Design On One-Layer Close-Fitting Acoustical Hoods Using A Simulated Annealing Method, Min-Chie Chiu

Journal of Marine Science and Technology–Taiwan

High noise levels in a multi-noise plant can be harmful to workers and will not only lead to psychological but also to physiological ailments. Consequently, noise control of industrial equipment becomes vital for workers. The study focuses on shape optimization of space-constrained close-fitting acoustic hoods. In this paper, a sound insertion loss used for evaluating the acoustic performance of an acoustical hood will be adopted. Numerical assessments of case studies for depressing the broadband noise emitted from motor-driven equipment by optimally designing a shaped one-layer close-fitting acoustic hood within a space constrained situation will be introduced. Additionally, simulated annealing (SA), …

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Shape Optimization Of Multi-Chamber Plenums With Multi-Layer Sound Absorers Using An Artificial Immune Method, Min-Chie Chiu Apr 2014

Shape Optimization Of Multi-Chamber Plenums With Multi-Layer Sound Absorers Using An Artificial Immune Method, Min-Chie Chiu

Journal of Marine Science and Technology–Taiwan

Because of the space constraints problem in practical engineering work, there is a growing need to optimize the acoustical performance of a sound-proofing device within a fixed space. The optimal mechanism used in adjusting either the plenum’s chamber or an internal sound absorber has been ignored. In order to maximize the acoustical performance of a plenum, a case study of depressing a diesel engine noise by using three kinds of optimally shaped multi-chamber acoustical plenums lined with three kinds of multi-layer sound absorbers is introduced. On the basis of constrained weight and space in the plenum, a low cost optimal …

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Dynamics And Cutting Stability Of Dynamically Loaded Worktable Subjected To Elastic Supports, Kuo-Chiang Cha, Nenzi Wang, Jen-Yi Liao Apr 2014

Dynamics And Cutting Stability Of Dynamically Loaded Worktable Subjected To Elastic Supports, Kuo-Chiang Cha, Nenzi Wang, Jen-Yi Liao

Journal of Marine Science and Technology–Taiwan

This paper investigated the dynamic characteristics and the cutting stability of a dynamically loaded worktable on elastic supports in a surface grinder. The operation of worktables is usually dynamically loaded in various positions, which results in a complex system of governing equations. In this study, the assumptions of elastic and rigid body modes of a free-free beam were specified in analyzing the worktable. By combining the Lagrange energy method with the technique of assumed mode expansion, the system of equations was developed. The absolute value of the maximum negative real part of the overall dynamic compliance (MNRPODC) and the limiting …

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Network Burst Monitoring And Detection Based On Fractal Dimension With Adaptive Time-Slot Monitoring Mechanism, Hsiao-Wen Tin, Shao-Wei Leu, Shun-Hsyung Chang, Gene Eu Jan Dec 2013

Network Burst Monitoring And Detection Based On Fractal Dimension With Adaptive Time-Slot Monitoring Mechanism, Hsiao-Wen Tin, Shao-Wei Leu, Shun-Hsyung Chang, Gene Eu Jan

Journal of Marine Science and Technology–Taiwan

This study proposed an approach to measure the burstiness of network traffic based on fractal dimensions (FDs). By definition, burstiness is the degree of variation in network traffic. This study defined two types of FDs: (1) the FD of network traffic that describes the flow variation of network traffic, and (2) the FD of the range that describes the degree of flow dispersal. The proposed method uses an adaptive time-slot monitoring mechanism to monitor the network. The relevant FDs are derived from measurements obtained during each time slot in a monitoring window. This study conducted experiments using NS2 simulation data. …

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The Least Squares Trefftz Method And The Method Of External Source For The Eigenfrequencies Of Waveguides, Hui-Ming Fang, Chia-Ming Fan, Yan-Cheng Liu, Sung-Shan Hsiao Dec 2013

The Least Squares Trefftz Method And The Method Of External Source For The Eigenfrequencies Of Waveguides, Hui-Ming Fang, Chia-Ming Fan, Yan-Cheng Liu, Sung-Shan Hsiao

Journal of Marine Science and Technology–Taiwan

In this study, the least squares Trefftz method (LSTM) is adopted for analyzing the eigenfrequencies problems governed by homogeneous Helmholtz equations. The Trefftz method, one kind of boundary-type meshless collocation methods, does not need mesh generation and numerical quadrature. Since the system of linear algebraic equations obtained by Trefftz method is highly ill-conditioned, the least squares method is adopted to stabilize the numerical scheme in this study. In the eigenproblem, the response amplitudes from an external source are used to determine the resonant frequencies. By adding an external source, the homogeneous boundary condition becomes inhomogeneous. Then we can employ the …

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An Effective Illumination Compensation Method For Face Recognition, Yea-Shuan Huang, Chu-Yung Li Dec 2013

An Effective Illumination Compensation Method For Face Recognition, Yea-Shuan Huang, Chu-Yung Li

Journal of Marine Science and Technology–Taiwan

Face recognition is very useful in many applications, such as safety and surveillance, intelligent robot, and computer login. The reliability and accuracy of such systems will be influenced by the variation of background illumination. Therefore, how to accomplish an effective illumination compensation method for human face image is a key technology for face recognition. Our study uses several computer vision techniques to develop an illumination compensation algorithm to processing the single channel (such as grey level or illumination intensity) face image. The proposed method mainly consists of three processing modules: (1) Homomorphic Filtering, (2) Ratio Image Generation, and (3) Anisotropic …

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Automatic Location For Multi-Symbology And Multiple 1d And 2d Barcodes, Daw-Tung Lin, Chin-Lin Lin Dec 2013

Automatic Location For Multi-Symbology And Multiple 1d And 2d Barcodes, Daw-Tung Lin, Chin-Lin Lin

Journal of Marine Science and Technology–Taiwan

Multi-symbology barcode location is a practical and challenging issue. Image-based barcode recognition techniques are robust and extendable approaches for reading versatile one-dimensional (1D) and two-dimensional (2D) barcodes. Most methods may work for a single 1D or 2D barcode or rely on a unique pattern to locate a single 1D or 2D barcode. This work proposes a general localization framework for extraction of real barcodes under complex backgrounds when multiple symbology types exist in the same snapshot for 1D barcodes, 2D barcodes, or both. There are five steps of the proposed algorithm: image grayscale conversion, adaptive thresholding, application of a modified …

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Physical Models For Simulating Ship Stability And Hydrostatic Motions, Shyh-Kuang Ueng Dec 2013

Physical Models For Simulating Ship Stability And Hydrostatic Motions, Shyh-Kuang Ueng

Journal of Marine Science and Technology–Taiwan

In this paper, efficient physics models are presented for simulating ship hydrostatic motions caused by sea waves, cargoes and flooding water. Based on the stability theory of ship, a ship is regarded as a floating body whose stability is indicated by its gravity, buoyancy and meta centers. These stability centers are influenced by cargoes, sea waves, flooding water and the ship mass. Variations of these stability centers create torques and forces which cause the ship to heave, pitch and roll. Because of the irregularity of the ship shape, analytical solutions of these stability centers do not exist. In this work, …

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Traffic Monitoring And Event Analysis Based On Integrated Multivideo And Petri Net Process, Chang-Lung Tsai Dec 2013

Traffic Monitoring And Event Analysis Based On Integrated Multivideo And Petri Net Process, Chang-Lung Tsai

Journal of Marine Science and Technology–Taiwan

Decreasing traffic accidents and events are one of the most important responsibilities for all of the governments in the world. However, it is difficult to exactly measuring the traffic condition. To find out the root cause of traffic accidents and restore the occurrence of traffic events, a traffic monitor and event analysis mechanism based on multi-videos processing and Petri net analysis techniques is proposed. In which, the traffic information is collected through the deployment of cameras at intersection of heavy traffic area. After then, all of the collected information is provided for constructing multiviewpoint traffic model. The significant features are …

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A Heat Island Observation Via Modis And Concurrent Helicopter-Borne Ir Imager, Tsung-Hua Kuo, Gin-Rong Liu, Tang-Huang Lin, Chia-Wen Lan, Chi-Ping Huang Dec 2013

A Heat Island Observation Via Modis And Concurrent Helicopter-Borne Ir Imager, Tsung-Hua Kuo, Gin-Rong Liu, Tang-Huang Lin, Chia-Wen Lan, Chi-Ping Huang

Journal of Marine Science and Technology–Taiwan

In this study, observations and aerial surveys were conducted in delineating the heat island patterns. Concurrent datasets from the satellite-borne MODIS sensor and helicopter-borne thermal IR imager were employed. The sampling data in this experiment covered an area exceeding 100 km2 in Taiwan’s western plain. A more than 10°C temperature difference between different sampling points could be observed in this area. The relationship between the surface temperature and vegetation index values was also showed. Results showed that the surface canopy and the air humidity together played an important role in the surface temperature increase.

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An Effective Color-Difference-Based Demosaicking Method, Yea-Shuan Huang, Sheng-Yi Cheng Dec 2013

An Effective Color-Difference-Based Demosaicking Method, Yea-Shuan Huang, Sheng-Yi Cheng

Journal of Marine Science and Technology–Taiwan

This paper proposes an effective color-difference-based (ECDB) interpolation algorithm for color filter array (CFA) image demosaicking. A CFA image consists of a set of spectrally selective filters which are arranged in an interleaved pattern such that only one color component is sampled at each pixel location. To improve the quality of reconstructed fullcolor images from CFA images, the ECDB algorithm first analyzes the samples immediately around a missing green pixel to determine suitable samples for interpolating the value of this missing green pixel. After finishing the interpolation operations of all the missing green pixels, a complete green plane (i.e G …

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Vehicle Counting Without Background Modeling, Cheng-Chang Lien, Cheng-Ta Hsieh, Ming-Hsiu Tsai Dec 2013

Vehicle Counting Without Background Modeling, Cheng-Chang Lien, Cheng-Ta Hsieh, Ming-Hsiu Tsai

Journal of Marine Science and Technology–Taiwan

In general, the vision-based methods for vehicle detection/tracking may face the problems of illumination variation, shadows, or swaying trees. In this study, we propose a novel vehicle detection method without background modeling to overcome the aforementioned problems. First, a modified block-based frame differential method is established to quickly detect the moving vehicles without the influences of rapid illumination variations. Second, the precise vehicles’ regions are extracted with the dual foregrounds fusion method. Third, a texture-based object segmentation method is proposed to segment each vehicle from the merged foreground image blob and remove the shadows. Fourth, based on the concept of …

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Determining The Internal Structure Of Cement-Based Materials By Using Mri Techniques, Hsiang-Wei Chiang, Ran Huang, Chia-Jung Tsai Dec 2013

Determining The Internal Structure Of Cement-Based Materials By Using Mri Techniques, Hsiang-Wei Chiang, Ran Huang, Chia-Jung Tsai

Journal of Marine Science and Technology–Taiwan

The primary concerns of the internal structure of cementbased materials involve the distribution of pores, pore size, and the manner in which they are connected. Thoroughly understanding the distributive rules of pores and the approaches to breaking their links can contribute considerably to enhancing the durability of cement-based materials. Several methods are used to measure the pores of cement-based materials; however, they cannot determine the exact location of pores or structural links. Magnetic resonance imaging (MRI) has been widely applied in physical examinations and has matured to the level of being able to obtain 3D images of the organs of …

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Determination Of Mortar Saturation Methods Based On Mri Scanning Image, Hsiang-Wei Chiang, Ran Huang Aug 2013

Determination Of Mortar Saturation Methods Based On Mri Scanning Image, Hsiang-Wei Chiang, Ran Huang

Journal of Marine Science and Technology–Taiwan

Magnetic resonance imaging (MRI) is widely used in the medical field and among one of the greatest inventions in recent years. In MRI images, the bright zone denotes signals that are generated by water in the specimen. However, solid cement-based materials lack water. Therefore, developing a method to achieve optimal saturation for cement-based materials is crucial for MRI scanning. In this study, the immersion, boiling, and vacuum methods were used to achieve saturation for various mortar specimens with w/c ratios of 0.45, 0.55, and 0.65. By comparing MRI images and absorption test results, we found that the vacuum method tends …

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Identification Of Pipelines From The Secondary Reflect Wave Travel Time Of Ground-Penetrating Radar Waves, Kun-Fa Lee, Tan-K Wang1, Yu-Ming Kang, Cheng-Sung Wang, Kuo-An Lin Aug 2013

Identification Of Pipelines From The Secondary Reflect Wave Travel Time Of Ground-Penetrating Radar Waves, Kun-Fa Lee, Tan-K Wang1, Yu-Ming Kang, Cheng-Sung Wang, Kuo-An Lin

Journal of Marine Science and Technology–Taiwan

When using ground-penetrating radar to identify underground pipelines of similar dielectric constants (i.e. PE and PVC), misidentification is quite common. In this study, we apply reflected travel time of radar waves into the PE- and PVC- dielectric constants and the differentiation becomes possible. We have conducted the experiments using the nonmetal PE- and PVC- pipelines as well as the heavy metal (iron) pipelines in a water environment. Based on a travel- time calculation, the dielectric constants of non-metal pipelines with similar composition (PE ＝ 2.3 and PVC ＝ 3.0) were quite close. The error between the experimental and theoretical values …

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Bayesian-Network-Based Hydro-Power Fault Diagnosis System Development By Fault Tree Transformation, Chaur-Gong Jong, Sou-Sen Leu Aug 2013

Bayesian-Network-Based Hydro-Power Fault Diagnosis System Development By Fault Tree Transformation, Chaur-Gong Jong, Sou-Sen Leu

Journal of Marine Science and Technology–Taiwan

Currently, fault diagnosis of reservoir facilities relies mostly on check-list evaluation. The results and qualities of evaluation are limited by experience and ability of the evaluators, which may not achieve the goal of systematic assessment in a consistent manner. To overcome the limitation of the traditional approach, this research develops a fault diagnosis and evaluation system for reservoir facility by utilizing multi-state Fault-Tree Analysis (FTA) technique, in conjunction with Bayesian Networks (BN) which incorporate expert experiences through lateral linkages among BN nodes and weighting factors. The system has been used to analyze and verify against three hydro-power systems currently in …

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A Lean Prebid Planning Model For Construction Contractors: A Case Study In Vietnam, Hui Ping Tserng, Samuel Yen-Liang Yin, Thanh Long Ngo Aug 2013

A Lean Prebid Planning Model For Construction Contractors: A Case Study In Vietnam, Hui Ping Tserng, Samuel Yen-Liang Yin, Thanh Long Ngo

Journal of Marine Science and Technology–Taiwan

Prebid planning is an essential function of construction project management that allows contractors to obtain projects with low cost while achieving other criteria. It also helps contractors during project execution and management. This research applied the manufacturing industry’s lean theory to propose a lean prebid planning model (LPPM) for construction contractors. The LPPM can significantly eliminate the main types of waste in construction projects because it effectively combines three important concepts in the manufactureing industry: transformation, workflow, and value generation. This model includes seven arrangement steps, which are described systematically to help contractors with real-world applications. A case study was …

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Experimental Study On The Motions Of A Mooring Ship In Mixed Waves, Xian-Ying Shi, Yang Yang, Ning-Chuan Zhang, Yu-Xin Huang Aug 2013

Experimental Study On The Motions Of A Mooring Ship In Mixed Waves, Xian-Ying Shi, Yang Yang, Ning-Chuan Zhang, Yu-Xin Huang

Journal of Marine Science and Technology–Taiwan

By employing the method of bimodal spectral simulations, a series of experiments were performed on a 266,000 m3 LNG ship moored to an island berth in mixed waves. In the physical model experiments, a special effort was made to investigate how changing wave conditions affect the motion responses of the mooring ship in mixed waves. Therefore, this paper mainly engages in the analysis of such effects resulted from wave condition changes of mixed waves from such perspectives as the distribution of high- and low-frequency energy, the periodic changes of low-frequency swells, the wave-height changes of low-frequency swells, and the wave-height …

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Comparison Of Different Wind Stress Effects On Sst And Sss In The East China Sea Region, Hung-Jen Lee, Shih-Jen Huang, Shenn-Yu Chao, Kon-Kee Liu Aug 2013

Comparison Of Different Wind Stress Effects On Sst And Sss In The East China Sea Region, Hung-Jen Lee, Shih-Jen Huang, Shenn-Yu Chao, Kon-Kee Liu

Journal of Marine Science and Technology–Taiwan

Ocean circulations closely associated with the changes of wind system are investigated using a three-dimensional tidecirculated coupling model. Based on the coupling model, we apply different wind datasets, to some extent reflecting wind system variations associated with global climate change, but constant monthly temperature and salinity fields to assess the effect of differing wind strength stresses in the East China Sea region, leading to significant influences on hydrographic fields. In the model based on the Hellman-Rosenstein wind dataset, more distant from the mouth of the Changjiang River (Yangtze River), the Yellow Sea Warm Current strengthens because of the wind stress; …

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A Real Case Study On The State Of Corrosion Of The Spanish Boats, José A Orosa, Juan José Galán, Mar Toledano Aug 2013

A Real Case Study On The State Of Corrosion Of The Spanish Boats, José A Orosa, Juan José Galán, Mar Toledano

Journal of Marine Science and Technology–Taiwan

In this real case study we analyze various corrosion problems encountered in Spanish fleets and present possible solutions. As a first step, we developed a statistical analysis of the north Mediterranean Sea fleets to define the age of the vessels, hull construction material and main activities involved. As a result, different corrosion problems were identified as well as solutions like paint, sacrificial anodes and impressed currents, and of course, improved design. Generally, we can state that, according to the results obtained, a series of incidents have increased the repair and maintenance costs of the vessels in the area under study

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Shape Optimization Of One-Chamber Perforated Mufflers Filled With Wool Using Simulated Annealing, Min-Chie Chiu Aug 2013

Shape Optimization Of One-Chamber Perforated Mufflers Filled With Wool Using Simulated Annealing, Min-Chie Chiu

Journal of Marine Science and Technology–Taiwan

Research on dissipative and reactive mufflers has been addressed. However, the acoustical performance ―sound transmission loss (STL)― of mufflers within a constrained space is often insufficient. In this paper, to improve the acoustical efficiency, a one-chamber perforated muffler filled with sound absorbing wool optimized by using simulated annealing (SA) in conjunction with the numerical decoupling technique is presented. A numerical case in eliminating a broadband noise is also introduced. To verify the reliability of SA optimization, optimal noise abatements for the pure tone are exemplified. Before the SA operation can be carried out, the accuracy of the mathematical models has …

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Model Reference Robust Control For Marine Propulsion Systems With Model Uncertainty Caused By Hull Deformation, Zhixiong Li, Xinping Yan, Li Qin, Chengqing Yuan, Zhongxiao Peng Aug 2013

Model Reference Robust Control For Marine Propulsion Systems With Model Uncertainty Caused By Hull Deformation, Zhixiong Li, Xinping Yan, Li Qin, Chengqing Yuan, Zhongxiao Peng

Journal of Marine Science and Technology–Taiwan

A marine propulsion system can be strongly coupled with the hull deformation in a large-scale ship. The interaction of this coupling dynamics increases the nonlinearity and complexity of the control model. Traditional control method based on the empirical PID (proportion-integration-differentiation) parameters has difficulty in dealing with the model uncertainty caused by the hull deflection. However, up to date, limited work has been done to address the model uncertainty problem of the marine propulsion system. It is therefore imperative to develop feasible and effective control systems that take the model uncertainty into account. In this study, a new method based on …

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The Application Of The Genetic Adaptive Neural Network In Landslide Disaster Assessment, Jing-Wen Chen, Yung-Sheng Chue, Yie-Ruey Chen Aug 2013

The Application Of The Genetic Adaptive Neural Network In Landslide Disaster Assessment, Jing-Wen Chen, Yung-Sheng Chue, Yie-Ruey Chen

Journal of Marine Science and Technology–Taiwan

This study applied the Genetic Adaptive Neural Network (GANN) structure to satellite image classification and the assessment of landslide disaster. First, the study conducted quantitative analysis of the various factors of slope development and natural environmental hazards in some parts of the catchment areas of the Laonong River in Southern Taiwan. Meanwhile, using the weighting ratios of various disaster causing factors inferred from the best structure of GANN, this study explored the degree of slope land disturbance. Then, this study incorporated the relationship between rainfall and landslides to draw a landslide potential map using the discriminant analysis approach combined with …

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Model Simulation Of Asian Dust And Iron Depositions Over The East Asian Marginal Seas, Fujung Tsai Aug 2013

Model Simulation Of Asian Dust And Iron Depositions Over The East Asian Marginal Seas, Fujung Tsai

Journal of Marine Science and Technology–Taiwan

This study applies a dust model to investigate Asian dust and iron depositions on the East Asian marginal sea during the months of the northeasterly monsoon from November to May, when dust events are often observed. Simulated dry and wet depositions of dust are compared with measurements obtained from Taipei, Taiwan. According to the model simulation, higher concentrations of atmospheric dust occur from March to May over East Asia, resulting in greater dry and wet deposition fluxes of dust and iron within these months than other months. The monthly averaged dry and wet deposition fluxes of iron are 0.6 and …

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Prediction Of Bridge Pier Scour Using Genetic Programming, Chuan-Yi Wang, Han-Peng Shih, Jian-Hao Hong, Rajkumar V Raikar Aug 2013

Prediction Of Bridge Pier Scour Using Genetic Programming, Chuan-Yi Wang, Han-Peng Shih, Jian-Hao Hong, Rajkumar V Raikar

Journal of Marine Science and Technology–Taiwan

This paper presents the use of genetic programming (GP) as a tool to predict pier scour depths based on clear-water conditions of laboratory measurements by past researchers. Four main dimensionless parameterspier width, approaching flow depth, threshold flow velocity, and channel open-ratio are considered for predicting the scour depth. The performance of the GP equation is verified by comparing the results with those obtained by empirical equations. It is found that the scour depth at bridge piers can be efficiently predicted using the GP model. The advantage of the GP model is confirmed by comparing the GP results of scour depths …

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A Study Of Energy Saving Control Strategy For An Integrated Environment Control System Applied To Ship Hull Painting, Tzong-Shing Lee, Li-Wen Chang, Yew-Khoy Chuah Jun 2013

A Study Of Energy Saving Control Strategy For An Integrated Environment Control System Applied To Ship Hull Painting, Tzong-Shing Lee, Li-Wen Chang, Yew-Khoy Chuah

Journal of Marine Science and Technology–Taiwan

An integrated environment control system (IECS) is proposed to satisfy the requirements of IMO (International Maritime Organization) for ship hull painting. The IECS has four elements for environment control, namely, desiccant dehumidification, heating, cooling, and ventilation. Five operating modes are proposed, with each operating mode consists of one to more elements in the IECS system. Energy saving operating mode is selected based on the weather conditions and the conditions of painting work. Energy saving control strategy is applied to each operating mode. Theoretical energy models of the different operation modes are presented, along with the control schemes for the annual …

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The Influence Of Mixture Variables For The Alkali-Activated Slag Concrete On The Properties Of Concrete, Chi-Che Hung, Jiang-Jhy Chang Jun 2013

The Influence Of Mixture Variables For The Alkali-Activated Slag Concrete On The Properties Of Concrete, Chi-Che Hung, Jiang-Jhy Chang

Journal of Marine Science and Technology–Taiwan

In this study, the influence of three mixture variables named Sand/Aggregate ratio, Liquid/Binder ratio and Paste/Aggregate ratio on the concrete properties were studied. The properties of fresh concrete including the slump, air content and unit weight were examined. In addition, the mechanical properties such as the compressive strength, elastic modulus and splitting tensile strength were studied. Results showed that the alkaliactivated slag concrete has superior strength. The 28-day compressive strength can reach 80% of the 90-day compressive strength. In addition, the influence of the Liquid/Binder ratio on the 28-day compressive strength is not as apparent as the water/cement ratio is …

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Numerical Investigation On The Effects Of Wave Grouping On The Motion Of Moored Ddms Platform, Xing-Gang Wang, Zhao-Chen Sun, Shu-Xiu Liang, Si Liu, Shu-Xue Liu, Jun-Bin Luo Jun 2013

Numerical Investigation On The Effects Of Wave Grouping On The Motion Of Moored Ddms Platform, Xing-Gang Wang, Zhao-Chen Sun, Shu-Xiu Liang, Si Liu, Shu-Xue Liu, Jun-Bin Luo

Journal of Marine Science and Technology–Taiwan

The random wave groups with the same wave parameters, such as significant wave height, period and overshoot parameter, but with different wave groupiness are simulated by an empirical wave envelope spectrum involved the group height factor GFH and group length factor GLF based on field measured sea waves. A geometrically nonlinear finite element method based on the total Lagrangian formulation is developed to calculate the mooring-line dynamics. Coupled dynamic analysis of DDMS (Deep Draft Multi-Spar) platform and the attached mooring lines under the action of wave groups with different groupiness in deep water is executed in time domain. The effects …

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The Experimental Study On Local Scour Around A Circular Pipe Undergoing Vortex-Induced Vibration In Steady Flow, Bing Yang, Tao Yang, Jian-Lin Ma, Jin-Sheng Cui Jun 2013

The Experimental Study On Local Scour Around A Circular Pipe Undergoing Vortex-Induced Vibration In Steady Flow, Bing Yang, Tao Yang, Jian-Lin Ma, Jin-Sheng Cui

Journal of Marine Science and Technology–Taiwan

The local scour around a circular pipe undergoing vortexinduced vibration is investigated experimentally in a water flume. The typical characteristic of local scour is analyzed in detail. The influences of initial gap-to-diameter ratio (e0/D), the mode of pipe vibration and the sand type on the local scour are discussed. Experimental results indicate that there exists strong intensity of scour when the pipe moves close to the surface of the sandy bed. The vibration of the pipe results in the rapid development of sandy bed’s scouring. With the increase of gap-to-diameter ratio the distance between the center of the pipe and …

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Shape Optimization Of Multi-Chamber Side Inlet/Outlet Mufflers Hybridized With Multiple Perforated Intruding Tubes Using A Genetic Algorithm, Min-Chie Chiu, Ying-Chun Chang Jun 2013

Shape Optimization Of Multi-Chamber Side Inlet/Outlet Mufflers Hybridized With Multiple Perforated Intruding Tubes Using A Genetic Algorithm, Min-Chie Chiu, Ying-Chun Chang

Journal of Marine Science and Technology–Taiwan

The use of perforated-tube side mufflers for depressing venting noise within a constrained space has been prevalent in modern industries. Also, research on mufflers equipped with side inlets/outlets has been thoroughly documented. However, research on shape optimization of side inlet/outlet mufflers hybridized with multiple open-ended perforated intruding tubes which may enhance acoustic performance has gone unnoticed. Therefore, we wish to not only analyze the sound transmission loss (STL) of side inlet/outlet mufflers but also to optimize their best design shape within a limited space. In this paper, the generalized decoupling technique and the plane wave theory used in solving the …

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