Experimental Research on the Surf-Riding Region for High Speed Vessels

2015 ◽  
Author(s):  
Atsuo Maki ◽  
Yoshiki Miyauchi
Keyword(s):  
Experimental Research ◽  
High Speed ◽  
Safety Assessment ◽  
Estimation Methods ◽  
Model Experiments ◽  
Size Limitation ◽  
Analytical Estimation ◽  
Free Running ◽  
Surface Combatant ◽  
Surf Riding

It is well known that surf-riding phenomenon is the prerequisite of the broaching-to in following and quartering conditions. For the safety assessment of the fast vessel such as surface combatant sand patrol crafts, the estimation of the surf-riding condition is important. Therefore, so far several experimental efforts have been made. However, in these previous researches, the free running model experiments in high speed region, i.e.up to Froude number of 0.6 or 0.7, have not been conducted because of tank size limitation. As shown in this paper, there are occurrence and disappearance boundaries of surf-riding in lower and faster region, respectively. In our study, free running model experiments are carried out in high speed region, and then both boundaries are experimentally obtained. By using obtained results, the analytical estimation methods proposed by the authors can be well validated. Furthermore, the free running model experiments in irregular seas are also conducted. Then, surf-riding phenomenon in irregular seas is also discussed.

The Impact of Structural Reforms and Regulations on the Demand Side in the Railway Industry

2019 ◽  
Vol 18 (1) ◽  
pp. 1-33
Author(s):  
Fumitoshi Mizutani
Keyword(s):  
Market Structure ◽  
Vertical Integration ◽  
High Speed ◽  
Fixed Effect Model ◽  
Structural Reform ◽  
Estimation Methods ◽  
Public Ownership ◽  
Estimation Model ◽  
Passenger Demand ◽  
The Impact

Abstract The main purpose of this study is to evaluate factors affecting passenger rail demand, with special attention to the effects of structural reform/regulation and competition. In order to do this, we use data obtained from 30 OECD countries for the 24 years from 1990 to 2013. As structural reform/regulation and competition variables, we take the OECD’s five kinds of regulatory indices: (i) overall, (ii) entry, (iii) public ownership, (iv) vertical integration, and (v) market structure; and for competition variables, we take (vi) rail passenger-freight ratio, (vii) rail share, and (viii) high-speed train ratio. As estimation methods, both the fixed effect model and the Hausman-Taylor estimation model are used. The major findings are as follows. First, competition as competitiveness (i.e. the share of rail, passenger over freight ratio) increases passenger demand. And the existence of high-speed trains increases passenger demand. Second, overall, entry regulation, and market structure have no significant effect on demand. Third, public ownership affects passenger demand positively. Last, vertical integration reduces passenger demand.

Experimental Research on Cavitation Characteristics of a Novel Hybrid Journal Bearing

2013 ◽  
Vol 420 ◽  
pp. 74-77
Author(s):  
Ying Yang ◽  
Jing Hua Dai ◽  
Xu Li
Keyword(s):  
Experimental Research ◽  
High Speed ◽  
Work Performance ◽  
Journal Bearing ◽  
Rupture Zone ◽  
Oil Film ◽  
Rotating Speed ◽  
Supply Pressure ◽  
Experimental Rig

Under high and super high speed, the oil film of a journal bearing is easy to crack and then becomes cavitation. The existence of cavitation has a great effect on the work performance of the bearing. The cavitation mechanism of a spiral oil wedge journal bearing was investigated on the experimental rig. The effects of rotating speed and supply pressure on the cavitation shape of oil film and the number of cavitation strip in the rupture zone were analyzed. The results show that the cavitation shape of oil film is a long strip. The number of cavitation strip increases when supply pressure has been improved, and the location of oil outlet must be designed optimally.

Experimental Research on the Emission Characteristics of City Taxies

2013 ◽  
Vol 295-298 ◽  
pp. 1529-1534
Author(s):  
Long Lin Sun ◽  
Wen Wei Huang ◽  
Mou Rong Gao
Keyword(s):  
High Precision ◽  
Experimental Research ◽  
High Speed ◽  
Emission Characteristics ◽  
Experiment Data ◽  
Mobile Emission

The taxies’ emission experiments on urban roads are carried out with a high-precision mobile emission analyzer. Then the emission characteristics are analyzed. The experiment data show that the high speed, the low acceleration and the low VSP will be helpful to decrease the emission and the long mileage will worsen the emission.

Research on the Characteristic of Diesel Elastic-Plate Impingement Spray

2012 ◽  
Vol 433-440 ◽  
pp. 116-122
Author(s):  
Chang Yuan Wang ◽  
Fu Shui Liu ◽  
Xiang Rong Li
Keyword(s):  
Experimental Research ◽  
Elastic Plate ◽  
High Speed ◽  
Incident Angle ◽  
Injection Pressure ◽  
High Speed Photography ◽  
Research Results ◽  
Free Jet ◽  
Constant Volume Chamber ◽  
Spray Droplets

A series of experimental research results on the characteristic of diesel elastic-plate impingement spray using High Speed Photography camera are presented in this paper. The experiments were carried out in a constant volume chamber specially designed, which can hold a high ambiance pressure. The special fixed device was designed so that the elastic-plate can be fixed on the spray path, meanwhile the spray incident angle and height can be changed. The free jet spray and elastic-plate impingement spray was compared under the same experimental condition including different injection pressure and different background pressure. Experimental research showed that impingement spray droplets diffuse more quickly than free jet spray.

Design and Testing Outline for a Free Running Model of a High Speed Craft

2020 ◽  
Author(s):  
Xinguo Wang ◽  
Jack Bonoli ◽  
Madeline Cohen ◽  
Mirjam Fürth
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Six Degrees Of Freedom ◽  
High Interest ◽  
Outdoor Environments ◽  
Free Running ◽  
Industry Professionals ◽  
Design And Testing ◽  
Very High ◽  
Testing Plan

Hydrodynamics of High Speed Craft is a topic of very high interest for recreational boaters and industry professionals alike. This project aims to be a first step toward conducting such experiments in exposed outdoor environments. This paper will outline a preliminary design and testing plan of a free running model of a high speed craft. The proposed free running model will be subjected to all six degrees of freedom, self propelled, autonomously controlled, and will be exposed to weather elements.

Hydrodynamic Aspects on Vulnerability Criteria for Surf-Riding of Ships

2014 ◽  
Vol 66 (2) ◽  
Author(s):  
Yuto Ito ◽  
Naoya Umeda ◽  
Hisako Kubo
Keyword(s):  
Empirical Formula ◽  
Global Bifurcation ◽  
Quantitative Agreement ◽  
Hydrodynamic Theory ◽  
Safety Level ◽  
Slender Body Theory ◽  
Model Experiments ◽  
Intact Stability ◽  
Surf Riding ◽  
Wave Induced

For developing the International Maritime Organization (IMO) second-generation intact stability criteria regarding broaching, draft vulnerability criteria for surf-riding were agreed at the IMO in 2012. This paper describes their hydrodynamic backgrounds with captive model experiments for seven ships, a hydrodynamic theory and a random process theory. In the first level vulnerability criteria, a ship is required to reduce her Froude number of less than 0.3 in case of severe following waves. For predicting the surf-riding threshold in a global bifurcation theory, it is necessary to precisely estimate wave-induced surge force. Thus, the authors execute captive model experiments for three ships in model basins. As a result, we confirmed that the Froude-Krylov calculation overestimates the amplitude of wave-induced surge force so that an empirical formula for regulatory application is presented. For investigating the reason of this discrepancy, a slender body theory assuming low encounter frequency is applied to the situation where a ship runs with a wave. This theory suggests that change of wave-making resistance due to incident wave could reduce the amplitude of the wave-induced surge force and quantitative agreement with model experiment requires the use of CFD or an empirical formula. Thus, the authors can recommend the use of experimental correction formula for the vulnerability criteria. Based on sample calculation results of surf-riding probability of six ships in the North Atlantic, the safety level to be required in the criteria is proposed.

Commercializing an Automatically Deployable Rollover Protective Structure (AutoROPS) for a Zero-Turn Riding Mower: Initial Product Safety Assessment Criteria

2004 ◽  
Author(s):  
J. R. Etherton ◽  
E. A. McKenzie ◽  
J. R. Powers
Keyword(s):  
Electromagnetic Interference ◽  
High Speed ◽  
Safety Assessment ◽  
Human Error ◽  
Product Safety ◽  
Current Phase ◽  
Protective Structure ◽  
Private Industry ◽  
Cooperative Effort ◽  
Safety Research

Fatal injuries have occurred to operators of zero-turn riding mowers when these machines rolled over during high speed sharp turns or on uneven terrain. These mowers are frequently operated in low clearance conditions such as around trees and when loaded onto low-roofed trailers. The automatically deployable rollover protective structure (AutoROPS) can provide both protection during rollover events and the capability to operate a mower in low clearance conditions. Until recently, AutoROPS technology development has occurred only in a government laboratory. In the current phase of development, private industry has taken an interest in the AutoROPS technology and is pursuing, with NIOSH, the product testing and development needed to commercialize the AutoROPS on a zero-turn riding mower. The government’s role, as a partner with private industry in bringing new safety technology into practical application, is discussed. Importantly, for the AutoROPS product to be as effective as possible, it should not introduce additional, unacceptable risks. Previous product safety assessments led by government laboratories are reviewed. These assessments were made to minimize hazards in products developed in government labs. A product safety assessment was performed on the AutoROPS during its design phase. In addition to minimizing the severity and frequency of operator injury resulting from an accidental rollover, the assessment considered 1) environmental factors such as corrosion, electromagnetic interference, and vibration; 2) human error avoidance; and 3) safeguard reliability analysis. This assessment was a cooperative effort between the safety engineering design team at the Division of Safety Research of the National Institute for Occupational Safety and Health; a ROPS manufacturer; and a zero-turn riding mower manufacturer. Design features are being incorporated into the prototype AutoROPS to address hazards encountered in normal use of these machines.

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