On two methods of determining the forced speed reduction due to the deck wetness

2016 ◽  
Vol 0 (2) ◽  
Author(s):  
Oleh I. Solomentsev ◽  
Li Tkhan Bin
Keyword(s):  
Speed Reduction ◽  
Deck Wetness

Quantification of the impact of traffic incidents on speed reduction: A causal inference based approach

2021 ◽  
Vol 157 ◽  
pp. 106163
Author(s):  
Danni Cao ◽  
Jianjun Wu ◽  
Xianlei Dong ◽  
Huijun Sun ◽  
Xiaobo Qu ◽  
...  
Keyword(s):  
Causal Inference ◽  
Traffic Incidents ◽  
Speed Reduction ◽  
The Impact

Investigation of planing craft maneuverability using full-scale tests

2021 ◽  
pp. 147509022110303
Author(s):  
Kazem Sadati ◽  
Hamid Zeraatgar ◽  
Aliasghar Moghaddas
Keyword(s):  
Full Scale ◽  
Performance Characteristics ◽  
Forward Speed ◽  
Speed Reduction ◽  
Planing Craft ◽  
Full Scale Tests ◽  
Turning Maneuver

Maneuverability of planing craft is a complicated hydrodynamic subject that needs more studies to comprehend its characteristics. Planing craft drivers follow a common practice for maneuver of the craft that is fundamentally different from ship’s standards. In situ full-scale tests are normally necessary to understand the maneuverability characteristics of planing craft. In this paper, a study has been conducted to illustrate maneuverability characteristics of planing craft by full-scale tests. Accelerating and turning maneuver tests are conducted on two cases at different forward speeds and rudder angles. In each test, dynamic trim, trajectory, speed, roll of the craft are recorded. The tests are performed in planing mode, semi-planing mode, and transition between planing mode to semi-planing mode to study the effects of the craft forward speed and consequently running attitude on the maneuverability. Analysis of the data reveals that the Steady Turning Diameter (STD) of the planing craft may be as large as 40 L, while it rarely goes beyond 5 L for ships. Results also show that a turning maneuver starting at planing mode might end in semi-planing mode. This transition can remarkably improve the performance characteristics of the planing craft’s maneuverability. Therefore, an alternative practice is proposed instead of the classic turning maneuver. In this practice, the craft traveling in the planing mode is transitioned to the semi-planing mode by forward speed reduction first, and then the turning maneuver is executed.

scholarly journals Airflow Characteristics According to the Change in the Height and Porous Rate of Building Roofs for Efficient Installation of Small Wind Power Generators

2021 ◽  
Vol 13 (10) ◽  
pp. 5688
Author(s):  
Jangyoul You ◽  
Kipyo You ◽  
Minwoo Park ◽  
Changhee Lee
Keyword(s):  
Wind Speed ◽  
Wind Power ◽  
Turbulence Intensity ◽  
Flow Characteristics ◽  
High Porosity ◽  
Power Generators ◽  
Speed Reduction ◽  
Reduction Effect ◽  
Wind Power Generators ◽  
The Impact

In this paper, the air flow characteristics and the impact of wind power generators were analyzed according to the porosity and height of the parapet installed in the rooftop layer. The wind speed at the top was decreasing as the parapet was installed. However, the wind speed reduction effect was decreasing as the porosity rate increased. In addition, the increase in porosity significantly reduced turbulence intensity and reduced it by up to 40% compared to no railing. In the case of parapets with sufficient porosity, the effect of reducing turbulence intensity was also increased as the height increased. Therefore, it was confirmed that sufficient parapet height and high porosity reduce the effect of reducing wind speed by parapets and significantly reducing the turbulence intensity, which can provide homogeneous wind speed during installation of wind power generators.

A Lightweight Split-Torque Transmission for a 330 KW Helicopter

1982 ◽  
Vol 196 (1) ◽  
pp. 11-22 ◽  
Author(s):  
G White
Keyword(s):  
Gear Train ◽  
Main Rotor ◽  
Speed Reduction ◽  
Torque Transmission ◽  
Current Production ◽  
Gear Trains ◽  
Fixed Axis ◽  
Three Stages ◽  
A Current ◽  
Split Torque

A simple split-torque gear train is used as the main rotor transmission of a single-engine helicopter. Overall speed reduction ratio achieved is 103:1 between the engine at a nominal 36 000 rev/min and the main rotor at 350 rev/min. This ratio is generated from three stages of fixed-axis gear trains containing only eight gears. Alternative configurations are outlined and discussed. Comparison with a current production design shows the split torque arrangement offers reductions in weight, height, and drive train losses. A low total of gears and bearings offers the potential for improved reliability.

Finite-Element Analysis of the Magnetostatic Field of a Coaxial Magnetic Gear Device

2015 ◽  
Vol 764-765 ◽  
pp. 289-293
Author(s):  
Yi Chang Wu ◽  
Han Ting Hsu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Magnetic Flux ◽  
High Speed ◽  
Field Analysis ◽  
Element Analysis ◽  
Magnetostatic Field ◽  
Speed Reduction ◽  
Dimensional Finite Element ◽  
Magnetic Gear

This paper presents the magnetostatic field analysis of a coaxial magnetic gear device proposed by Atallah and Howe. The structural configuration and speed reduction ratio of this magnetic gear device are introduced. The 2-dimensional finite-element analysis (2-D FEA), conducted by applying commercial FEA software Ansoft/Maxwell, is performed to evaluate the magnetostatic field distribution, especially for the magnetic flux densities within the outer air-gap. Once the number of steel pole-pieces equals the sum of the pole-pair numbers of the high-speed rotor and the low-speed rotor, the coaxial magnetic gear device possesses higher magnetic flux densities, thereby generating greater transmitted torque.

Methods to Reduce Traffic Speed in High-Pedestrian Rural Areas

2003 ◽  
Vol 1828 (1) ◽  
pp. 31-37 ◽  
Author(s):  
Ali Kamyab ◽  
Steve Andrle ◽  
Dennis Kroeger ◽  
David S. Heyer
Keyword(s):  
Rural Areas ◽  
Speed Limit ◽  
Single Word ◽  
Short Term ◽  
Speed Reduction ◽  
Traffic Calming ◽  
Reduction Strategies ◽  
Long Term Impact ◽  
The Impact

Many Minnesota counties are faced with the problem of high vehicle speeds through towns or resort areas that have significant pedestrian traffic. The impact of speed reduction strategies in high-pedestrian areas in rural counties of Minnesota was investigated. Speed data were collected at two selected study sites under their existing conditions ("no-treatment" or "before" condition) and after the proposed speed reduction strategies were installed. Second "after" data conditions were collected to study the short-term and long-term impact of the implemented strategies. The traffic-calming techniques employed at the Twin Lakes site consisted of removable pedestrian islands and pedestrian crossing signs. A dynamic variable message sign that sent a single-word message ("Slow") to motorists traveling over the speed limit was installed at the Bemidji site. The research study shows that the traffic-calming strategy deployed in Twin Lakes was effective in significantly reducing the mean speed and improving speed limit compliance in both the short term and long term. Despite proven effectiveness, the deployed speed reduction treatment in Bemidji Lake failed to lower the speed at the study site. The single-word message on the sign and the location of the sign, as well as a lack of initial enforcement, were the primary reasons for such failure.

An Optimality Criterion for the Structural Optimization of Machine Elements

2005 ◽  
Vol 127 (3) ◽  
pp. 415-423 ◽  
Author(s):  
C.-P. Teng ◽  
J. Angeles
Keyword(s):  
Structural Optimization ◽  
Optimality Criterion ◽  
Mass Reduction ◽  
Speed Reduction ◽  
Optimum Dimension ◽  
Novel Approach ◽  
Cam Follower ◽  
Machine Elements ◽  
A Current

Methods of structural optimization have been studied and developed over the last three decades. An important aspect of structural optimization pertains to the condition under which the loads are applied. Most machine structures in operation are subject to loads varying as functions of time. In this paper, a novel approach is proposed to cope with loads whose magnitudes vary within given bounds and with variable directions. The underlying ideas are applied to the structural optimization of the roller-carrying disk of a novel class of cam-follower speed reduction devices termed Speed-o-Cam (SoC). Results obtained in this paper are compared with a current prototype and with an intermediate design in which the dimensions of the roller pins are optimized. Combined with the optimum dimension of the roller pins, our structural-optimization results lead to an improvement of almost twice the stiffness with a mass reduction of 40% of the original prototype.

Analysis on the Performance of Deckwetness of Sandglass-type and Cylindrical Floating Bodies

2016 ◽  
Vol 60 (03) ◽  
pp. 145-155
Author(s):  
Ya-zhen Du ◽  
Wen-hua Wang ◽  
Lin-lin Wang ◽  
Yu-xin Yao ◽  
Hao Gao ◽  
...  
Keyword(s):  
Transfer Functions ◽  
Linear Response Theory ◽  
Second Order ◽  
Irregular Waves ◽  
Wave Loads ◽  
Floating Bodies ◽  
Drift Motion ◽  
First Order ◽  
Series Of Experiments ◽  
Deck Wetness

In this paper, the influence of the second-order slowly varying loads on the estimation of deck wetness is studied. A series of experiments related to classic cylindrical and new sandglass-type Floating Production, Storage, and Offloading Unit (FPSO) models are conducted. Due to the distinctive configuration design, the sand glass type FPSO model exhibits more excellent deck wetness performance than the cylindrical one in irregular waves. Based on wave potential theory, the first-order wave loads and the full quadratic transfer functions of second-order slowly varying loads are obtained by the frequency-domain numerical boundary element method. On this basis, the traditional spectral analysis only accounting for the first-order wave loads and time-domain numerical simulation considering both the first-order wave loads and nonlinear second-order slowly varying wave loads are employed to predict the numbers of occurrence of deck wetness per hour of the two floating models, respectively. By comparing the results of the two methods with experimental data, the shortcomings of traditional method based on linear response theory emerge and it is of great significance to consider the second-order slowly drift motion response in the analysis of deck wetness of the new sandglass-type FPSO.

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