Principles of design of fluid transport systems in zoology

Science ◽  
1990 ◽  
Vol 249 (4972) ◽  
pp. 992-1000 ◽  
Author(s):  
M LaBarbera
Keyword(s):  
Fluid Transport ◽  
Transport Systems ◽  
Principles Of Design

One-Dimensional Unsteady Periodic Flow Model with Boundary Conditions Constrained by Differential Equations

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
Nhan T. Nguyen
Keyword(s):  
Differential Equations ◽  
Boundary Conditions ◽  
Euler Equations ◽  
Periodic Boundary ◽  
Closed Loop ◽  
Fluid Transport ◽  
Periodic Boundary Conditions ◽  
Transport Systems ◽  
Variable Approach ◽  
Upwind Method

This paper describes a modeling method for closed-loop unsteady fluid transport systems based on 1D unsteady Euler equations with nonlinear forced periodic boundary conditions. A significant feature of this model is the incorporation of dynamic constraints on the variables that control the transport process at the system boundaries as they often exist in many transport systems. These constraints result in a coupling of the Euler equations with a system of ordinary differential equations that model the dynamics of auxiliary processes connected to the transport system. Another important feature of the transport model is the use of a quasilinear form instead of the flux-conserved form. This form lends itself to modeling with measurable conserved fluid transport variables and represents an intermediate model between the primitive variable approach and the conserved variable approach. A wave-splitting finite-difference upwind method is presented as a numerical solution of the model. An iterative procedure is implemented to solve the nonlinear forced periodic boundary conditions prior to the time-marching procedure for the upwind method. A shock fitting method to handle transonic flow for the quasilinear form of the Euler equations is presented. A closed-loop wind tunnel is used for demonstration of the accuracy of this modeling method.

Bifurcation Patterns and Branching Exponents in Branchial Vessels in Tadpoles of Xenopus laevis Daudin during Metamorphosis-3D-Measurements from Microvascular Corrosion Casts

2001 ◽  
Vol 7 (S2) ◽  
pp. 1188-1189
Author(s):  
B. Minnich ◽  
H. Bartel ◽  
R. Karch ◽  
W. Schreiner ◽  
A. Lametschwandtner
Keyword(s):  
Fluid Transport ◽  
Vascular System ◽  
Three Dimensional ◽  
Circulatory System ◽  
Transport Systems ◽  
Corrosion Casts ◽  
Parent Vessel ◽  
Tubular System ◽  
Anuran Tadpole ◽  
Existing Data

IntroductionFluid transport systems of organisms [1] in general and the blood vascular system in particular are considered to be optimally designed. From Murray's laws [2] it is concluded that an arterial bifurcation where the diameter of the parent vessel (d0) relates to the larger (d1) and the smaller daughter vessel (d2) according to d03 = d13 + d23 is optimal. Interestingly, existing data predominantly refer to arterial branchings of the fully developed circulatory system of mammals. to the best of our knowledge there are no data available on arterial bifurcations and venous mergings in an initially growing but then regressing tubular system of blood vessels as it is found in the gill filter apparatus of the anuran tadpole where the highly complex three-dimensional vascular network totally disappears at the end of metamorphosis.

scholarly journals A design principle of root length distribution of plants

2019 ◽  
Vol 16 (161) ◽  
pp. 20190556
Author(s):  
Yeonsu Jung ◽  
Keunhwan Park ◽  
Kaare H. Jensen ◽  
Wonjung Kim ◽  
Ho-Young Kim
Keyword(s):  
Water Uptake ◽  
Root Length ◽  
Fluid Transport ◽  
Root Length Density ◽  
Global Climate ◽  
Plant Root ◽  
Length Distribution ◽  
Biological Data ◽  
Transport Systems ◽  
Network Systems

Shaping a plant root into an ideal structure for water capture is increasingly important for sustainable agriculture in the era of global climate change. Although the current genetic engineering of crops favours deep-reaching roots, here we show that nature has apparently adopted a different strategy of shaping roots. We construct a mathematical model for optimal root length distribution by considering that plants seek maximal water uptake at the metabolic expenses of root growth. Our theory finds a logarithmic decrease of root length density with depth to be most beneficial for efficient water uptake, which is supported by biological data as well as our experiments using root-mimicking network systems. Our study provides a tool to gauge the relative performance of root networks in transgenic plants engineered to endure a water deficit. Moreover, we lay a fundamental framework for mechanical understanding and design of water-absorptive growing networks, such as medical and industrial fluid transport systems and soft robots, which grow in porous media including soils and biotissues.

scholarly journals On the Principles of Design of Transport Nodes

2022 ◽  
Vol 19 (4) ◽  
pp. 6-12
Author(s):  
P. A. Kozlov ◽  
S. P. Vakulenko ◽  
V. P. Kozlova ◽  
N. Yu. Evreenova
Keyword(s):  
Rational Design ◽  
Systemic Approach ◽  
Transport Systems ◽  
Natural Form ◽  
Basic Principles ◽  
Main Method ◽  
Principles Of Design ◽  
The One ◽  
Definition Of

The methodology developed by the authors refers to designing, calculating, and optimising transport nodes based on the original systemic approach as a main method. The use of the methodology will make it possible to design transport nodes more rationally and to evaluate their development projects more correctly.A «system» is understood as a general natural form of structuring organised substance, which enables it to function stably in a changeable environment. The basic principles are formulated as follows: the system consists of elements, each of which is also a system; active self-maintenance is developed in the system, that is, active actions are counteracting external adverse influences; it is shown that self-maintenance is provided by adaptability, and in transport systems the self-maintenance is particularly provided by adaptive technology.A contradiction (a dialectical one) arises: on the one hand, the elements are independent systems that have their own system parameters and mechanisms for their active maintenance, and on the other hand, they are subordinate creatures capable of flexibly changing their work to maintain the parameters of the supersystem. It is necessary to find harmony between the levels of development of these opposite properties. Transport nodes are also considered from these systemic positions. Exposition of several definitions of nodes by leading national scientists is followed by a statement showing that they all contradict the new systemic approach.Suggested system definition of a node describes it as a set of stations. The authors also propose a new classification of transport nodes, formulate criteria for their rational design depending on the classes, and propose correct design and optimisation principles. 

Teaching Impact and Evaluation Methodology Assessment in a Fluid Mechanics Course: Student’s Perceptions

2017 ◽  
Author(s):  
M. Teresa Sena-Esteves ◽  
Cristina Morais ◽  
Anabela Guedes ◽  
Isabel Brás Pereira ◽  
Margarida Ribeiro ◽  
...  
Keyword(s):  
Learning Styles ◽  
Fluid Transport ◽  
Theory And Practice ◽  
Practical Work ◽  
Assessment Process ◽  
Basic Knowledge ◽  
Evaluation Methodology ◽  
Transport Systems ◽  
Theoretical Concepts ◽  
Practical Applications

Fluid Transport Systems topic is of fundamental importance in most Engineering areas. In this topic basic knowledge must be taught yet students normally resist and do not perform well in theoretical syllabus. In order to reinforce the importance of these issues, and based on teachers’ perceptions and experience, a change was made in the assessment process: a Practical Work and different moments and types of assessment were introduced. The objective is to evaluate the influence of these changes in the students’ final grades and to obtain students’ perceptions regarding these changes, and to know which teaching/learning methodologies are most effective. The students’ perceptions were analyzed through a questionnaire developed and validated for that purpose. Fifty students (88% of the enrolled students) carried out this new course format and answered the questionnaire. It is interesting to observe that most students (55.1%) do not perceive this course as essentially theoretical and 37% view it as balanced between theory and practice. One of the main reasons could be the fact that students realize that practical applications proposed during classes are enough to understand the theoretical concepts (75.5%). Globally students preferred several assessment moments (mini tests) to just one. Regarding the Practical Work, it was well accepted by students. The technical and soft skills promoted by the Practical Work as well as students’ learning styles were also analyzed through the questionnaires. The majority of students (71.4%) learn through the creation of concepts (abstract conceptualization) and perform things by an active experimentation. The grades obtained in the different moments of assessments were crossed with the final and Practical Work grades. It is worth pointing out that students increased their grades with the Practical Work.

Attenuation of High Amplitude Vibrations With Particle Dampers

2002 ◽  
Author(s):  
Michael Y. Yang ◽  
Gary H. Koopmann ◽  
George A. Lesieutre ◽  
Stephen A. Hambric
Keyword(s):  
Fluid Transport ◽  
Extreme Temperature ◽  
Excitation Amplitude ◽  
High Amplitude ◽  
Transport Systems ◽  
Design Parameters ◽  
Gap Size ◽  
Physical Damage ◽  
Transient Phenomena ◽  
Particle Dampers

Fluid transport systems are rarely at steady state. Transient phenomena, such as water hammer, can inflict severe physical damage. Repair costs can soar into the millions of dollars (Myers, 1997), and can reduce or even halt operation. Such high amplitude vibrations may be attenuated with particle dampers, which are beds of small particles placed in an attached enclosure or contained void. Vibration of the enclosure causes the particles to collide with each other and with the enclosure walls, resulting in energy dissipation through inelastic impacts and friction. Particle dampers have many advantages over conventional viscoelastic treatments including lower cost, increased robustness, greater effectiveness at high amplitudes and the ability to operate in extreme-temperature environments. Previous papers focus on exploration of sensitivity to design parameters, modeling techniques, and effective applications. However, there still remains much that is unknown about the phenomena and design of particle dampers. In this paper, experiments were performed to explore the effects of friction, excitation amplitude, and particle gap size. The formation of an oily residue on the colliding surfaces when certain materials were used increased friction and reduced damper effectiveness. This agrees with the theoretical prediction made by Mansour and Filho (1974). Damping was found to peak at an optimum gap size. Increasing the excitation amplitude resulted in higher damping and reduced sensitivity to the optimum gap size. Overall, the particle damper was deemed to be successful, increasing the loss factor of a clamped beam by over 10 times with a damper/structure mass ratio of only 0.016.

scholarly journals Student’s Perceptions Regarding Assessment Changes in a Fluid Mechanics Course

2019 ◽  
Vol 9 (2) ◽  
pp. 152 ◽  
Author(s):  
Teresa Sena-Esteves ◽  
Cristina Morais ◽  
Anabela Guedes ◽  
Isabel Brás Pereira ◽  
Margarida Marques Ribeiro ◽  
...  
Keyword(s):  
Fluid Transport ◽  
Collaborative Work ◽  
Transport Systems ◽  
Learning Assessment ◽  
Traditional Teaching ◽  
Course Content ◽  
Single Moment ◽  
Teaching Learning ◽  
The Impact ◽  
Student's Perceptions

The main objective of this study is to evaluate students’ perceptions regarding different methods of assessment and which teaching/learning methodologies may be the most effective in a Fluid Transport System course. The impact of the changes in the assessment methodology in the final students’ grades and attendance at theoretical classes is also analysed, and the results show that students’ attendance at theoretical classes changed significantly. The students prefer and consider more beneficial for their learning assessment through several questions/problems and small tests during theoretical lessons instead of a single moment of evaluation. For them, the traditional teaching/learning methodology is still considered the most effective one. At the same time, students perceive that the development of the Practical Work (PW) and several moments of assessment had positive repercussions on the way they focus on the course content and keep up with the subjects taught, providing knowledge on the area under study, encouraging collaborative work and stimulating the students’ intellectual curiosity. Largely, students agree that the PW is an important tool in their learning process and recommend it as a teaching activity. In general, students are confident with the knowledge acquired with the PW and feel able to size fluid transport systems.

Ionic requirements of proximal tubular sodium transport. III. Selective luminal anion substitution

1979 ◽  
Vol 236 (3) ◽  
pp. F268-F277 ◽  
Author(s):  
R. Green ◽  
J. H. Bishop ◽  
G. Giebisch
Keyword(s):  
Sodium Transport ◽  
Concentration Gradient ◽  
Fluid Transport ◽  
Chloride Transport ◽  
Chloride Concentration ◽  
Transport Systems ◽  
Sodium Reabsorption ◽  
Perfusion Fluid ◽  
Moderate Amount ◽  
Proximal Tubular

The effect of substitution of luminal anions on sodium and fluid absorption in rat renal proximal convoluted tubules was studied with continuous luminal microperfusion methods. Substitution of bicarbonate in the control Ringer perfusion fluid by 25 mM acetate reduced net sodium reabsorption by 40%; substitution by chloride reduced it by 25%; and substitution by cyclamate reduced it by 70%. Infusion of acetazolamide reduced net sodium and fluid transport in all cases except chloride-Ringer perfusion. Cyanide added to the perfusion fluid inhibited fluid and sodium movement completely when there was no imposed chloride concentration gradient, but only reduced fluid and solute movement by 68% when a nominal 36 mM transepithelial chloride concentration gradient existed. We conclude from these observations that passive forces for sodium reabsorption can account for a moderate amount of sodium transport, that the effects of acetazolamide in low concentrations are dependent on the presence of bicarbonate in the lumen, and that some anions alter net sodium transport either by reducing the availability of permeant anion for co-transport with sodium or by a direct effect on the sodium and/or chloride transport systems.

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