Simplified Analytical Calculation and Modification of the Crushing Forces of Intersection Units in Vessel-Bridge Collisions

2020 ◽  
Author(s):  
Yin Faqiang ◽  
Pan Jin ◽  
Huang Shiwen ◽  
Xu Mingcai
Keyword(s):  
Small Angle ◽  
Large Angle ◽  
Analytical Formula ◽  
Analytical Calculation ◽  
Typical Structure ◽  
Analytical Formulas ◽  
Ship Collision ◽  
Collision Force ◽  
Inclined Angle ◽  
The Impact

Abstract Because of the increasingly busy maritime trade, the number of bridges damaged by ship-bridge collision also increases. In order to reduce the serious losses caused by ship-bridge collision incidents, it is necessary to make a rapid estimation of ship collision forces. The simplified analytical formulas can be used to rapidly evaluate the collision force in ship collision accidents, but it is found that the existing simplified formulas are only applicable to bulb structures including small-angle inclined elements and not suitable for large-angle inclined elements which exist in ship-bridge collision. In this paper, the quasi-static crushing simulation of the bulbous structure with small-angle inclined angle elements is carried out, and the applicability of the simplified analytical formula of the intersection unit to the typical structure is verified. By comparing the simplified analytical results of the bow with the quasi-static simulation results and the ratio of the strength reduction factor to the effective crushing distance, it is found that the inclined angle of the inclined element will affect the impact force of the simplified analytical calculation. Then, finite element analysis of the truncated-type intersection structure with different element inclination angles are carried out, and the results show that the existing simplified analytical formula is no longer suitable for the calculation of collision force when the inclined angle is greater than 40°. For this reason, the existing simplified analytical formulas are modified for the large-angle inclined elements, and it can provide a certain reference calculation value for the collision force of vessel-bridge collision which includes large-angle inclined elements.

On the Importance of the Tax System in Marginal Cost of Funds Calculations

2011 ◽  
Vol 11 (1) ◽  
Author(s):  
Mickael Beaud
Keyword(s):  
General Equilibrium ◽  
Marginal Cost ◽  
Analytical Formula ◽  
Value Added ◽  
Tax Revenue ◽  
Empirical Estimates ◽  
Analytical Formulas ◽  
The Impact ◽  
Labor Income Taxation ◽  
Marginal Cost Of Funds

Abstract Several papers have attempted to derive computable analytical formulas for the Marginal Cost of Funds (MCF). However, this literature is often cast in the pure labor supply general equilibrium model, which is not completely consistent with real tax systems where Labor Income Taxation (LIT) is not the only instrument used by governments. Hence, we explicitly introduce Value-Added Taxation (VAT) on consumption goods in the conventional model, and we derive an analytical formula for the MCF which does incorporate general equilibrium interactions between the different tax bases. Then, we illustrate how much this matter for empirical estimates of MCF using French data. Our numerical example suggests that, when computing MCF for a LIT reform, taking account of the impact of LIT reform on tax revenue from VAT can make a great deal of difference, typically increasing MCF and accounting for around 0.2 to 0.8 of estimates. In addition, MCF is then really less likely to be less than one than in the conventional framework.

Effect of Impact Position and Initial Velocity on Structure of Collided Tanker

2011 ◽  
Vol 84-85 ◽  
pp. 199-203
Author(s):  
Wen Feng Wu ◽  
Wan Qing Wu ◽  
Zheng Mao Wang ◽  
Jian Li Yang
Keyword(s):  
Initial Velocity ◽  
Maritime Security ◽  
Impact Position ◽  
Complicated Process ◽  
Ship Collision ◽  
Collision Force ◽  
Energy Absorbing ◽  
The Impact ◽  
Force Displacement ◽  
Ship Speed

Ship-ship collision is a very complicated process, different collision parameters will lead to different results. Using ANSYS/LS-DYNA to build a model of ship-ship collision, it studies the side structure collision characteristics at different impact position and initial velocity. Based on the results of calculation, the collision force-displacement curves, energy absorbing-displacement curves, and the damage deformation of side structure are obtained. The simulation results indicate that changing the impact position and initial velocity will obtain the different form and degree deformation. In addition, the critical ship speed of ship shell ruptured is insured, which can offer the theoretical basis for maritime security management.

scholarly journals Improving Near Miss Detection in Maritime Traffic in the Northern Baltic Sea from AIS Data

2021 ◽  
Vol 9 (2) ◽  
pp. 180
Author(s):  
Lei Du ◽  
Osiris A. Valdez Banda ◽  
Floris Goerlandt ◽  
Pentti Kujala ◽  
Weibin Zhang
Keyword(s):  
Baltic Sea ◽  
Perceived Risk ◽  
Maritime Transportation ◽  
Near Miss ◽  
Automatic Identification ◽  
Identification System ◽  
Collision Risk ◽  
Ship Collision ◽  
The Impact ◽  
Ship Behavior

Ship collision is the most common type of accident in the Northern Baltic Sea, posing a risk to the safety of maritime transportation. Near miss detection from automatic identification system (AIS) data provides insight into maritime transportation safety. Collision risk always triggers a ship to maneuver for safe passing. Some frenetic rudder actions occur at the last moment before ship collision. However, the relationship between ship behavior and collision risk is not fully clarified. Therefore, this work proposes a novel method to improve near miss detection by analyzing ship behavior characteristic during the encounter process. The impact from the ship attributes (including ship size, type, and maneuverability), perceived risk of a navigator, traffic complexity, and traffic rule are considered to obtain insights into the ship behavior. The risk severity of the detected near miss is further quantified into four levels. This proposed method is then applied to traffic data from the Northern Baltic Sea. The promising results of near miss detection and the model validity test suggest that this work contributes to the development of preventive measures in maritime management to enhance to navigational safety, such as setting a precautionary area in the hotspot areas. Several advantages and limitations of the presented method for near miss detection are discussed.

A reciprocating permanent magnetic actuator for driving magnetic micro robots in fluids

2021 ◽  
pp. 095440622110145
Author(s):  
Chuan Qu ◽  
Yong-Chen Pei ◽  
Qing-Yuan Xin ◽  
Zhen-Xing Li ◽  
Long Xu
Keyword(s):  
Permanent Magnet ◽  
Analytical Calculation ◽  
Magnetic Actuator ◽  
Cross Sectional ◽  
Permanent Magnetic Actuator ◽  
Element Simulation ◽  
Micro Robot ◽  
Analytical Formulas ◽  
Motion Performance ◽  
Motion Characteristics

Magnetic-based driving applications are receiving increasing attention. This study proposed a novel reciprocating permanent magnetic actuator (PMA) to manipulate magnetic micro robots to impact and clear blockages inside fluid pipes in a linear path. The PMA consisted of a cylindrical permanent magnet and a crank slider structure. A straight pipe with a circular cross-sectional area was located in front of the actuator to study the driving performance of PMA. A micro permanent magnet with a cylinder shape was employed as a working robot for manipulation inside the pipe. Firstly, analytical formulas were derived to obtain the magnetic driving force acting on the micro robot and determine the most suitable magnet configuration. The finite element simulation verified the analytical calculation. The developed reciprocating PMA prototype was then introduced, and the PMA and micro robot’s motion performance was analysed. Lastly, preliminary experiments were carried out for evaluating the micro robot’s motion characteristics. Performance tests for different excitation frequencies, flow rates, viscosities, and axial distances, indicating that PMA could manipulate the magnetic micro robot inside the pipe. The results confirmed that the developed PMA could effectively drive the micro robot with the advantage of consecutive magnetic driving. Especially, the micro robot featured good flexibility, rapid response, and a simple structure, suggesting that this micro robot may play an important role in industrial and medical applications, such as blockage elimination and thrombus clearance.

Pre-Impact Configuration Designing of a Robot Manipulator for Impact Minimization

2017 ◽  
Vol 9 (3) ◽  
Author(s):  
Jingchen Hu ◽  
Tianshu Wang
Keyword(s):  
Impact Force ◽  
Robot Manipulator ◽  
Analytical Formula ◽  
Joint Space ◽  
Collision Problem ◽  
Spatial Operator ◽  
Inertia Ellipsoid ◽  
The Impact ◽  
Maximum Minimum ◽  
Simple Analytical Formula

This paper studies the collision problem of a robot manipulator and presents a method to minimize the impact force by pre-impact configuration designing. First, a general dynamic model of a robot manipulator capturing a target is established by spatial operator algebra (SOA) and a simple analytical formula of the impact force is obtained. Compared with former models proposed in literatures, this model has simpler form, wider range of applications, O(n) computation complexity, and the system Jacobian matrix can be provided as a production of the configuration matrix and the joint matrix. Second, this work utilizes the impulse ellipsoid to analyze the influence of the pre-impact configuration and the impact direction on the impact force. To illustrate the inertia message of each body in the joint space, a new concept of inertia quasi-ellipsoid (IQE) is introduced. We find that the impulse ellipsoid is constituted of the inertia ellipsoids of the robot manipulator and the target, while each inertia ellipsoid is composed of a series of inertia quasi-ellipsoids. When all inertia quasi-ellipsoids exhibit maximum (minimum) coupling, the impulse ellipsoid should be the flattest (roundest). Finally, this paper provides the analytical expression of the impulse ellipsoid, and the eigenvalues and eigenvectors are used as measurements to illustrate the size and direction of the impulse ellipsoid. With this measurement, the desired pre-impact configuration and the impact direction with minimum impact force can be easily solved. The validity and efficiency of this method are verified by a PUMA robot and a spatial robot.

scholarly journals Microstructure and Mechanical Properties of Modern 11%Cr Heat-Resistant Steel Weld Joints

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3430
Author(s):  
Grzegorz Golański ◽  
Jacek Słania ◽  
Marek Sroka ◽  
Paweł Wieczorek ◽  
Michał Urzynicok ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Welded Joints ◽  
Martensitic Steel ◽  
Base Material ◽  
Hardness Measurement ◽  
Power Industry ◽  
Strength Properties ◽  
Typical Structure ◽  
Δ Ferrite ◽  
The Impact

In addition to good high-temperature creep resistance and adequate heat resistance, steels for the power industry must have, among other things, good weldability. Weldability of such steels is one of the criteria determining whether or not the material is suitable for applications in the power industry. Therefore, when materials such as martensitic steel Thor 115 (T115) are introduced into the modern power industry, the quality and properties of welded joints must be assessed. The paper presents the results of metallographic and mechanical investigations of T115 martensitic steel welded joints. The analysis was carried out on joints welded with two filler metals: WCrMo91 (No. 1) and EPRI P87 (No. 2). The scope of the investigations included: microstructural investigations carried out using optical, scanning and transmission electron microscopy and mechanical testing, i.e., Vickers microhardness and hardness measurement, static tensile test and impact test. The macro- and microstructural investigations revealed correct structure of the weld, without welding imperfections. The microstructural investigations of joint No. 1 revealed a typical structure of this type of joint, i.e., the martensitic structure with numerous precipitates, while in joint No. 2, the so-called Nernst’s layers and δ-ferrite patches were observed in the weld fusion zone as well as the heat affected zone (HAZ). The mechanical properties of the test joints met the requirements for the base material. A slight influence of the δ-ferrite patch on the strength properties of joint No. 2 was observed, and its negative effect on the impact energy of HAZ was visible.

Prognosis of water levels in a moor groundwater system influenced by hydrology and water extraction using an artificial neural network 

2021 ◽  
Author(s):  
Sascha Flaig ◽  
Timothy Praditia ◽  
Alexander Kissinger ◽  
Ulrich Lang ◽  
Sergey Oladyshkin ◽  
...  
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Mean Squared Error ◽  
Meteorological Data ◽  
Water Levels ◽  
Typical Structure ◽  
Water Abstraction ◽  
Physical Knowledge ◽  
Artificial Neural ◽  
The Impact

<p>In order to prevent possible negative impacts of water abstraction in an ecologically sensitive moor south of Munich (Germany), a “predictive control” scheme is in place. We design an artificial neural network (ANN) to provide predictions of moor water levels and to separate hydrological from anthropogenic effects. As the moor is a dynamic system, we adopt the „Long short-term memory“ architecture.</p><p>To find the best LSTM setup, we train, test and compare LSTMs with two different structures: (1) the non-recurrent one-to-one structure, where the series of inputs are accumulated and fed into the LSTM; and (2) the recurrent many-to-many structure, where inputs gradually enter the LSTM (including LSTM forecasts from previous forecast time steps). The outputs of our LSTMs then feed into a readout layer that converts the hidden states into water level predictions. We hypothesize that the recurrent structure is the better structure because it better resembles the typical structure of differential equations for dynamic systems, as they would usually be used for hydro(geo)logical systems. We evaluate the comparison with the mean squared error as test metric, and conclude that the recurrent many-to-many LSTM performs better for the analyzed complex situations. It also produces plausible predictions with reasonable accuracy for seven days prediction horizon.</p><p>Furthermore, we analyze the impact of preprocessing meteorological data to evapotranspiration data using typical ETA models. Inserting knowledge into the LSTM in the form of ETA models (rather than implicitly having the LSTM learn the ETA relations) leads to superior prediction results. This finding aligns well with current ideas on physically-inspired machine learning.</p><p>As an additional validation step, we investigate whether our ANN is able to correctly identify both anthropogenic and natural influences and their interaction. To this end, we investigate two comparable pumping events under different meteorological conditions. Results indicate that all individual and combined influences of input parameters on water levels can be represented well. The neural networks recognize correctly that the predominant precipitation and lower evapotranspiration during one pumping event leads to a lower decrease of the hydrograph.</p><p>To further demonstrate the capability of the trained neural network, scenarios of pumping events are created and simulated.</p><p>In conclusion, we show that more robust and accurate predictions of moor water levels can be obtained if available physical knowledge of the modeled system is used to design and train the neural network. The artificial neural network can be a useful instrument to assess the impact of water abstraction by quantifying the anthropogenic influence.</p>

Design of floating bridge girders against accidental ship collision loads

2016 ◽  
Author(s):  
Yanyan Sha ◽  
Jørgen Amdahl
Keyword(s):  
Finite Element Models ◽  
Cruise Ship ◽  
Box Girder ◽  
Global Response ◽  
Ship Structure ◽  
Steel Box Girder ◽  
Floating Bridge ◽  
Bridge Girder ◽  
Ship Collision ◽  
The Impact

The Norwegian Public Roads Administration is running a project “Ferry free coastal route E39” which includes replacing ferry crossings by bridges or tunnels across fjords in Western Norway. A floating bridge concept was proposed in the fjord-crossing project for Bjørnefjorden. As there are regular cruise routes passing by the bridge, it raises the concern for the consequences of accidental ship collision with the bridge girder. During the collision, the interactions between the bridge girder and the ship structure can be significant. Thus, in the design of the proposed bridge it is vital to evaluate the safety of the ship and the bridge. In this paper, detailed finite element models of a cruise ship and a steel box girder are developed. The impact scenarios and structural damages are studied. The results show that the proposed bridge girder design is generally safe to resist normal accidental ship collision loads. Numerical model of the whole bridge is also developed for further study of bridge global response subjected to ship collision load.

Analytical and 3D Finite Element Study of the Deflection of an Elastic Cantilever Bilayer Plate

2010 ◽  
Vol 78 (1) ◽  
Author(s):  
M. Chekchaki ◽  
V. Lazarus ◽  
J. Frelat
Keyword(s):  
Thin Films ◽  
Finite Element ◽  
Three Dimensional ◽  
Analytical Formula ◽  
Mechanical Stresses ◽  
Linear Elastic ◽  
Wide Range ◽  
Finite Element Calculations ◽  
Analytical Formulas ◽  
Three Dimensional Elasticity

The mechanical system considered is a bilayer cantilever plate. The substrate and the film are linear elastic. The film is subjected to isotropic uniform prestresses due for instance to volume variation associated with cooling, heating, or drying. This loading yields deflection of the plate. We recall Stoney’s analytical formula linking the total mechanical stresses to this deflection. We also derive a relationship between the prestresses and the deflection. We relax Stoney’s assumption of very thin films. The analytical formulas are derived by assuming that the stress and curvature states are uniform and biaxial. To quantify the validity of these assumptions, finite element calculations of the three-dimensional elasticity problem are performed for a wide range of plate geometries, Young’s and Poisson’s moduli. One purpose is to help any user of the formulas to estimate their accuracy. In particular, we show that for very thin films, both formulas written either on the total mechanical stresses or on the prestresses, are equivalent and accurate. The error associated with the misfit between our theorical study and numerical results are also presented. For thicker films, the observed deflection is satisfactorily reproduced by the expression involving the prestresses and not the total mechanical stresses.

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