scholarly journals The smaller your mouth, the longer your snout: predicting the snout length of Syngnathus acus , Centriscus scutatus and other pipette feeders

2007 ◽  
Vol 4 (14) ◽  
pp. 561-573 ◽  
Author(s):  
Marc H.E de Lussanet ◽  
M Muller
Keyword(s):  
Mathematical Model ◽  
Cross Section ◽  
Angular Speed ◽  
Moment Of Inertia ◽  
Small Cross Section ◽  
Snout Length ◽  
Evolutionary Advantage ◽  
Feeding Kinematics

Like most ray-finned fishes ( Actinopterygii ), pipefishes ( Syngnathoidei ) feed by suction. Most pipefishes reach their prey by a rapid dorso-rotation of the head. In the present study, we analysed the feeding kinematics of the razor fish, Centriscus scutatus , and of the greater pipefish, Syngnathus acus in detail. We found capture times of as little as 4–6 ms for C. scutatus and 6–8 ms for S. acus . We then hypothesized that the long snout of pipefishes is optimal for such fast feeding. To test this, we implemented in a mathematical model the following considerations. To reach the prey as fast as possible, a low moment of inertia increases the head's angular speed, whereas a long snout decreases the angle over which the head must be turned. The model accurately predicted the snout lengths of a number of pipefishes. We found that the optimal snout length, with which a prey will be reached fastest, is inversely related to its cross-section. In spite of the small cross-section, the development of a long snout can be an evolutionary advantage because this reduces the time to approach the prey.

Hydraulic Transport of Sand/Shell Mixtures

2011 ◽  
Author(s):  
Robert C. Ramsdell ◽  
Sape A. Miedema ◽  
Arno M. Talmon
Keyword(s):  
Mathematical Model ◽  
Critical Velocity ◽  
Cross Section ◽  
Settling Velocity ◽  
Hydraulic Transport ◽  
Erosion Process ◽  
Large Area ◽  
Small Cross Section ◽  
Horizontal Cross Section ◽  
Sand Particles

When considering pumping shells through a pipeline we have to consider that the shells are not spherical, but more discs shaped. When shells settle they will settle like leaves where the biggest cross section is exposed to the drag. But when they settle, they will settle in the same orientation, flat on the sediment, so the sides of the shells are exposed to the horizontal flow in the pipeline. Since the side cross section is much smaller than the horizontal cross section, a much higher velocity is required to make them erode and go back into suspension. The settling velocity is much smaller because of the large area of the cross section. Even when the slurry velocity exceeds the settling velocity, there will always be some shells that will reach the bottom of the pipe due to the combination of settling velocity and turbulence. Once these shells are on top of the sediment they are hard to remove by erosion, because they lay flat on the surface and have a small cross section that is exposed to the flow compared with the weight of the shell. So although their settling velocity is much lower than equivalent sand particles, the erosion velocity is much higher. If we look at the beach in an area with many shells, we can always see the shells on top of the sand, covering the sand. In fact the shells are shielding the sand from erosion, because they are hard to erode. The bigger shells will also shield the smaller pieces, because the smaller pieces settle faster. Compare this with leaves falling from a tree, the bigger leaves, although heavier, will fall slower, because they are exposed to higher drag. The same process will happen in the pipeline. Shells settle slower than sand grains, so they will be on top of the bed (if there is a bed), just like on the beach. Since they are hard to erode, in fact they protect the bed from being eroded, even if the line speed is increased. The combination of high erosion velocity and the shell ‘protecting’ the bed means that even a small amount of shells can lead to relatively thick bed in the pipeline. But there will always be velocities above the bed that will make the shells erode. The paper describes the settling and erosion process of shells and the consequences of this on the critical velocity when pumping a sand/shell mixture through a pipeline. A mathematical model of the processes involved will be presented.

Development of a Mathematical Model for a Workpiece Heating and Cooling in a Protective Medium while Treatment under Pressure

2021 ◽  
Vol 410 ◽  
pp. 115-122
Author(s):  
Victoria V. Devyatiarova ◽  
Eugenia E. Balakhnina ◽  
Lilya M. Valeeva
Keyword(s):  
Mathematical Model ◽  
Cross Section ◽  
Arbitrary Shape ◽  
Thermal Conductivity Coefficient ◽  
Regression Equations ◽  
Heating And Cooling ◽  
Temperature Problem ◽  
Protective Medium ◽  
Computer Calculations ◽  
The Mathematical Model

The paper reviews and develops the mathematical model of plastic flow during the hot-forming processes. A flat non-stationary temperature problem for a cross-section of a long solid (rolled product) of arbitrary shape with different heat transfer conditions along the perimeter of the cross-section was considered. Equations for calculation of the thermal conductivity coefficient and heat capacity of tungsten billets were obtained in the temperature range of 700 - 1500°C, based on the literature data. Analytical dependences in form of regression equations were obtained, allowing for computer calculations of physical specifications of 11x11 mm VA grade tungsten billets in form of temperature functions with accuracy sufficient for practical calculations.

MATHEMATICAL MODEL OF TWO-DIMENSIONAL LAYERED PRESSURE FLOW IN THE AUGER CHANNEL

2018 ◽  
Author(s):  
А.В. ГУКАСЯН ◽  
В.С. КОСАЧЕВ ◽  
Е.П. КОШЕВОЙ
Keyword(s):  
Mathematical Model ◽  
Analytical Solution ◽  
Cross Section ◽  
Dynamic Pressure ◽  
Two Dimensional ◽  
Flow Dynamic ◽  
Pressure Flow ◽  
Rectangular Channels ◽  
Wide Range ◽  
Pressure Characteristics

Получено аналитическое решение двумерного слоистого напорного течения в канале шнека, позволяющее моделировать расходно-напорные характеристики прямоугольных каналов шнековых прессов с учетом гидравлического сопротивления формующих устройств и рассчитывать расходно-напорные характеристики экструдеров в широком диапазоне геометрии витков как в поперечном сечении, так и по длине канала. Obtained the analytical solution of two-dimensional layered pressure flow in the screw channel, allow to simulate the flow-dynamic pressure characteristics of rectangular channels screw presses taking into account the hydraulic resistance of the forming device and calculate the mass flow-dynamic pressure characteristics of the extruders in a wide range of the geometry of the coils, as in its cross section and along the length of the channel.

Detonation Propagation at Bend Angles in Channels of Small Cross Section

2018 ◽  
Vol 54 (5) ◽  
pp. 624-628
Author(s):  
E. V. Khaldeev ◽  
A. V. Bessonova ◽  
D. A. Pronin ◽  
Yu. M. Sustaeva ◽  
O. V. Shevlyagin
Keyword(s):  
Cross Section ◽  
Small Cross Section ◽  
Detonation Propagation ◽  
Bend Angles

scholarly journals Engineering of Light Electric Commercial Vehicle

2020 ◽  
Vol 19 (1) ◽  
pp. 63-75
Author(s):  
R. Dorofeev ◽  
A. Tumasov ◽  
A. Sizov ◽  
A. Kocherov ◽  
A. Meshkov ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Electric Vehicle ◽  
Electric Motor ◽  
Field Tests ◽  
Angular Speed ◽  
Maximum Energy ◽  
Driving Cycle ◽  
Thermal Calculation ◽  
Technical Solutions ◽  
The Mathematical Model

The paper describes the process and results of the development of the light commercial electric vehicle. In order to ensure maximum energy efficiency of the developed vehicle the key parameters of the original electric motor. The article also presents the results of power electronic thermal calculation. For the mathematical model of the vehicle, the driving cycle parameters of the electric platform were determined in accordance with UNECE Regulations No 83, 84. The driving cycle was characterized by four successive urban and suburban cycles. The mathematical model also takes into account the time phases of the cycle, which include idling, vehicle idling, acceleration, constant speed movement, deceleration, etc. The model of the electric part of the vehicle was developed using MatLab-Simulink (SimPowerSystems library) in addition to the mechanical part of the electric car. The electric part included the asynchronous electric motor, the motor control system and the inverter. This model at the output allows to obtain such characteristics of the electric motor as currents, flows and voltages of the stator and rotor in a fixed and rotating coordinate systems, electromagnetic moment, angular speed of rotation of the motor shaft. The developed model allowed to calculate and evaluate the performance parameters of the electric vehicle. Technical solutions of the electric vehicle design were verified by conducting strength calculations. In conclusion, the results of field tests of a commercial electric vehicle are presented.

Design of Observer for Direct Current Drive

2009 ◽  
Vol 147-149 ◽  
pp. 119-124
Author(s):  
Andrius Petrovas ◽  
Roma Rinkeviciene ◽  
Saulius Lisauskas
Keyword(s):  
Mathematical Model ◽  
Control Theory ◽  
State Space ◽  
Characteristic Equation ◽  
Direct Current ◽  
Angular Speed ◽  
Current Drive

Control theory proposes to apply observers in systems with uncertain plant parameters. Observers can be used for calculation of feedback gains and getting desired, even strictly determined response requirements. The paper considers design of controller for direct current drive. As state space variables are chosen armature current and angular speed of motor. Mathematical model of the motor, operating with load which is assumed as disturbance, is elaborated. Full order Luenberg observer is designed according to desired characteristic equation of system. The results of simulation are presented and discussed.

Provision of Long Item Materials

2013 ◽  
Vol 572 ◽  
pp. 257-260
Author(s):  
Markus Straub ◽  
Shu Jun Zhang ◽  
Carsten Manz ◽  
Kevin Hapeshi
Keyword(s):  
Case Studies ◽  
Cross Section ◽  
The Other ◽  
Small Cross Section ◽  
Plant Area

Purpose: This paper shows the effects of using Minomi on the provision of long items in the plant area. In details it will be evaluated if the Minomi principle is usable for the provision of long item material at the manufacturing area and what improvements can be achieved. Definitions of the term Minomi and the term long item: The term long item is used in the logistic sector for all materials that are longer than 2.5 meters, require individually packing and have a relatively small cross section [1,2]. The term Minomi has not been clearly defined. In practise, the term Minomi is often associated with a system that does not use boxes for the material provision [3]. Findings: Through the case studies, it has been found that additional advantages can be obtained by using Minomi for the provision of long items than the other existing methods.

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