Inspired by dipoles from the Electrical Circuits Theory, the Thermodynamic Tripoles are an origin... more Inspired by dipoles from the Electrical Circuits Theory, the Thermodynamic Tripoles are an original approach providing a common conceptual framework to various branches of Irreversible Engineering Thermodynamics, thus allowing them to cooperate in evaluating various irreversibilities. We find that a generic thermal machine can be described with two characteristic functions, while certain special cases (brakes, heat exchangers and reversible machines) need only one function. As a proof of validity, a formula for the mechanical power is found and then used to recover the known Curzon-Ahlborn result regarding endoreversible machines.
In order to study the human cardiovascular system, we develop a Windkessel model of the heart and... more In order to study the human cardiovascular system, we develop a Windkessel model of the heart and the blood vessels. This model can be used to study the time evolution of various thermodynamic parameters, in different regimes of the heart (high blood pressure, low blood pressure, normal blood pressure, high speed, low speed, normal speed etc.). We draw qualitative pressure-volume diagrams in order to apply the Finite Speed Thermodynamics (FST) to this model.
Starting from several simple hypotheses regarding the gas diffusion phenomena taking place throug... more Starting from several simple hypotheses regarding the gas diffusion phenomena taking place through the semipermeable walls of the capillaries and regarding the energy and substance balance in the organism, we show that: 1) Although there is no blood speed to maximize the oxygen transported by the cardiovascular system, there is a certain blood speed which maximizes the net power delivered by the organism. 2) Also, there exists an optimum number of capillaries maximizing this net power.
Presently it is estimated that on the entire planet about 50% of the deaths are because of cardio... more Presently it is estimated that on the entire planet about 50% of the deaths are because of cardiovascular diseases. From this follows the extraordinary importance of the research in the Cardio-Vascular-Pulmonary field. There is hope that Cardio-Vascular Physiology must and can add substantially to the understanding of this extremely complex system, which plays a vital role in the life and wellbeing of animals with blood (including humans). In recent years, this research has been substantially helped in the colossal effort of understanding the complexities of the finite speed processes in this system by Physics, Biological Thermodynamics and recently by the new branch of Irreversible Thermodynamics, Finite Speed Thermodynamics (FST). The components of the cardio-vascular-pulmonary system are viewed in TVF analogous to real thermal machines, which evidently work also with finite speed to produce or use mechanical power in order to obtain...
Resume. Le travail propose reconsidere l'approche du moteur de Carnot en tenant compte des di... more Resume. Le travail propose reconsidere l'approche du moteur de Carnot en tenant compte des dimensions physiques finies (conductances de transfert de chaleur) et de la vitesse finie du piston. L'irreversibilite inherente d’un moteur reel est approche par deux methodes, a savoir (1) la methode du ratio avec quelques resultats et conclusions fournies dans les documents precedents proposes par les auteurs, et (2) la methode du flux de la production d'entropie qui apparait particulierement pratique en raison de l’hypothese du fonctionnement en regime stationnaire de la machine. Le modele du moteur developpe a permis une optimisation formelle en utilisant le calcul des variations. Des resultats generiques sont rapportes dans le cas commun de la loi lineaire de transfert de chaleur. Diverses autres lois communes qui pourraient etre envisagees sont citees. La meme consideration a l'aide des travaux anterieurs de l'equipe permet de voir la sensibilite des resultats a la f...
We analyze The Time Correction Paradox: "Assuming that the past can be modified, then I will not ... more We analyze The Time Correction Paradox: "Assuming that the past can be modified, then I will not succeed in correcting any unwanted past event N-because then I would have no reason to go back and correct it." Despite the common intuition that (past) time is essential to this paradox, we show that it works exactly the same for future events, not only past events. Moreover, we show that the Multiverse hypothesis fails to solve the paradox (even admitting causal links between future and past). We finally show that the paradox can be stated and analyzed without employing any Temporal or Modal Logic, but in plain Classical Logic. 1. Paradoxul Introducem următorul paradox legat de călătoria în timp, pe care-l numim Paradoxul corecției temporale 1 : Să presupunem că am acces la o mașină ce poate modifica trecutul. Îmi pun problema să-o utilizez pentru a împiedica petrecerea unui eveniment nedorit N din trecut. Înainte de a apăsa butonul mașinii judec astfel: dacă voi apăsa butonul și mașina va funcționa, atunci în prezent ar trebui să constat că N nu s-a petrecut; dar eu acum constat că N s-a petrecut, ceea ce înseamnă că fie voi decide să nu apăs butonul, fie îl voi apăsa dar mașina nu va funcționa. Pe scurt, ipotezele sunt: a) evenimentul N s-a petrecut (istoria conține N) b) doresc ca N să nu se fi petrecut c) am posibilitatea să apăs butonul P al mașinii de modificare a trecutului d) mașina este reglată astfel încât apăsarea butonului P face ca istoria să nu conțină N. În cadrul acestor ipoteze este prezentat următorul raționament simplu: 1 Autorul a luat contact cu paradoxul în formularea Irinei Enache, în vârstă de 7 ani: "Tati, știi, m-am gândit că orice întoarcere în timp ca să rezolvi ceva e un paradox. Pentru că dacă te întorci și rezolvi, atunci în prezent nu mai ai niciun motiv să te întorci…"
Proceedings of the National Conference of Thermodynamics with International Participation (NACOT) "Present and Future in Thermodynamics", 2013
In order to study the human cardiovascular system, we develop a Windkessel model of the heart and... more In order to study the human cardiovascular system, we develop a Windkessel model of the heart and the blood vessels. This model can be used to study the time evolution of various thermodynamic parameters, in different regimes of the heart (high blood pressure, low blood pressure, normal blood pressure, high speed, low speed, normal speed etc.). We draw qualitative pressure-volume diagrams in order to apply the Finite Speed Thermodynamics (FST) to this model.
"Considering generic cost functions, we show that minimizing the cost (pump + pipes) of tree-like... more "Considering generic cost functions, we show that minimizing the cost (pump + pipes) of tree-like installations transporting a generic fluid to sinks with given flows and pressures follows two general laws:
1. The pump’s and pipes’ “cost per bar” is conserved in nodes (similarly to the flow).
2. In each Steiner node, the pipes’ cost gradients are in equilibrium.
The resulting configuration is also optimal in another sense: among all the networks with the same cost, this has minimum power dissipation and requires minimum pump pressure/power. Based on these results, we propose a local optimization algorithm which may be responsible for how biological networks (of blood vessels, capillary vessels etc.) minimize their cost. The algorithm takes into account the possible non-homogenous environment."
Lucrările Conferinței Internaționale ZILELE ACADEMICE ale Academiei de Științe Tehnice din România "Viața și activitățile în mari aglomerații urbane. București, prezent și viitor", 2012
Minimizing the cost of tree-like pipe networks at constant dissipated power follows two general l... more Minimizing the cost of tree-like pipe networks at constant dissipated power follows two general laws:
1. The “cost per dissipated watt” ratio is the same for all pipes.
2. In each node, defining along the pipes vectors equal to a certain power of the flow, they are in equilibrium.
The resulting configuration is also optimal in another sense: among all the networks with the same cost, this has minimum power dissipation. Based on these results, we propose a local optimization algorithm which may be responsible for how biological networks (of blood vessels, capillary vessels etc.) minimize their cost.
Zeno's paradox Achilles and the Tortoise shows that among the fundamental postulates regarding sp... more Zeno's paradox Achilles and the Tortoise shows that among the fundamental postulates regarding space, time and motion we have to include the idea that “In every Achillean race there exists a point in which the quicker one meets the slower one.” This idea does not follow from “Between two points there exists another,” and neither from “A moving body cannot get beyond a point without first passing through it”. It is independent and cannot be proved from these intuitions. Without this postulate, the meeting of the two contestants is not guaranteed. It is equivalent to the Completeness Axiom of the real numbers: “Every bounded monotone array has a limit.” Even admitting by axiom its existence, the meeting point cannot be specified finitely – exactly as Zeno says in Achilles and in The Dichotomy. The modern theory of the real numbers, defined by the Completeness Axiom and by the impossibility of finite description, is based on these ideas.
Prisoner's Dilemma is a type of interaction in which the Nash equilibrium does not bring the best... more Prisoner's Dilemma is a type of interaction in which the Nash equilibrium does not bring the best result for neither of the rational agents. The optimal result cannot be reached by way of reason, but can only be imposed from a level transcending the agents' rationality: they obey a common instinct which pushes them to cooperate irrationally. This instinct could be called Honor and, despite a strong temptation to explain it rationally, is not rooted in reason. The beneficiary of this systematic failure of reason is only as a side effect the individual, but it is hard wired in the individual for the benefit of the true replicators: the genes. That's why the Kantian moral rule “Ask yourself: What if everyone did that?...”, although incorrect as logical reasoning, nevertheless has some practical relevance – it can help us distinguish between the “irrational cooperative drive” stemming from our genes and some accidental irrational moods. These phenomena are most visible in situations dubbed “Prisoner's Co-Dilemma” (Prisoner's Dilemma combined with a simple dilemma), frequent in human interactions.
The students reason:" If we will have the test on the last day of the next week (be it Sunda... more The students reason:" If we will have the test on the last day of the next week (be it Sunday), then the previous day (Saturday) we could say:'There was no test either on any of the previous days, or today, so it's for sure we will have the test tomorrow.'But a test that we ...
Abstract: The goals of the paper are: to build a general model of the discussion; to define in a ... more Abstract: The goals of the paper are: to build a general model of the discussion; to define in a clear manner the phenomenon regularly called" dispute"; to define the argument and to build a model of the argumentation; to identify, to classify and to analyze the frequent ...
Inspired by dipoles from the Electrical Circuits Theory, the Thermodynamic Tripoles are an origin... more Inspired by dipoles from the Electrical Circuits Theory, the Thermodynamic Tripoles are an original approach providing a common conceptual framework to various branches of Irreversible Engineering Thermodynamics, thus allowing them to cooperate in evaluating various irreversibilities. We find that a generic thermal machine can be described with two characteristic functions, while certain special cases (brakes, heat exchangers and reversible machines) need only one function. As a proof of validity, a formula for the mechanical power is found and then used to recover the known Curzon-Ahlborn result regarding endoreversible machines.
In order to study the human cardiovascular system, we develop a Windkessel model of the heart and... more In order to study the human cardiovascular system, we develop a Windkessel model of the heart and the blood vessels. This model can be used to study the time evolution of various thermodynamic parameters, in different regimes of the heart (high blood pressure, low blood pressure, normal blood pressure, high speed, low speed, normal speed etc.). We draw qualitative pressure-volume diagrams in order to apply the Finite Speed Thermodynamics (FST) to this model.
Starting from several simple hypotheses regarding the gas diffusion phenomena taking place throug... more Starting from several simple hypotheses regarding the gas diffusion phenomena taking place through the semipermeable walls of the capillaries and regarding the energy and substance balance in the organism, we show that: 1) Although there is no blood speed to maximize the oxygen transported by the cardiovascular system, there is a certain blood speed which maximizes the net power delivered by the organism. 2) Also, there exists an optimum number of capillaries maximizing this net power.
Presently it is estimated that on the entire planet about 50% of the deaths are because of cardio... more Presently it is estimated that on the entire planet about 50% of the deaths are because of cardiovascular diseases. From this follows the extraordinary importance of the research in the Cardio-Vascular-Pulmonary field. There is hope that Cardio-Vascular Physiology must and can add substantially to the understanding of this extremely complex system, which plays a vital role in the life and wellbeing of animals with blood (including humans). In recent years, this research has been substantially helped in the colossal effort of understanding the complexities of the finite speed processes in this system by Physics, Biological Thermodynamics and recently by the new branch of Irreversible Thermodynamics, Finite Speed Thermodynamics (FST). The components of the cardio-vascular-pulmonary system are viewed in TVF analogous to real thermal machines, which evidently work also with finite speed to produce or use mechanical power in order to obtain...
Resume. Le travail propose reconsidere l'approche du moteur de Carnot en tenant compte des di... more Resume. Le travail propose reconsidere l'approche du moteur de Carnot en tenant compte des dimensions physiques finies (conductances de transfert de chaleur) et de la vitesse finie du piston. L'irreversibilite inherente d’un moteur reel est approche par deux methodes, a savoir (1) la methode du ratio avec quelques resultats et conclusions fournies dans les documents precedents proposes par les auteurs, et (2) la methode du flux de la production d'entropie qui apparait particulierement pratique en raison de l’hypothese du fonctionnement en regime stationnaire de la machine. Le modele du moteur developpe a permis une optimisation formelle en utilisant le calcul des variations. Des resultats generiques sont rapportes dans le cas commun de la loi lineaire de transfert de chaleur. Diverses autres lois communes qui pourraient etre envisagees sont citees. La meme consideration a l'aide des travaux anterieurs de l'equipe permet de voir la sensibilite des resultats a la f...
We analyze The Time Correction Paradox: "Assuming that the past can be modified, then I will not ... more We analyze The Time Correction Paradox: "Assuming that the past can be modified, then I will not succeed in correcting any unwanted past event N-because then I would have no reason to go back and correct it." Despite the common intuition that (past) time is essential to this paradox, we show that it works exactly the same for future events, not only past events. Moreover, we show that the Multiverse hypothesis fails to solve the paradox (even admitting causal links between future and past). We finally show that the paradox can be stated and analyzed without employing any Temporal or Modal Logic, but in plain Classical Logic. 1. Paradoxul Introducem următorul paradox legat de călătoria în timp, pe care-l numim Paradoxul corecției temporale 1 : Să presupunem că am acces la o mașină ce poate modifica trecutul. Îmi pun problema să-o utilizez pentru a împiedica petrecerea unui eveniment nedorit N din trecut. Înainte de a apăsa butonul mașinii judec astfel: dacă voi apăsa butonul și mașina va funcționa, atunci în prezent ar trebui să constat că N nu s-a petrecut; dar eu acum constat că N s-a petrecut, ceea ce înseamnă că fie voi decide să nu apăs butonul, fie îl voi apăsa dar mașina nu va funcționa. Pe scurt, ipotezele sunt: a) evenimentul N s-a petrecut (istoria conține N) b) doresc ca N să nu se fi petrecut c) am posibilitatea să apăs butonul P al mașinii de modificare a trecutului d) mașina este reglată astfel încât apăsarea butonului P face ca istoria să nu conțină N. În cadrul acestor ipoteze este prezentat următorul raționament simplu: 1 Autorul a luat contact cu paradoxul în formularea Irinei Enache, în vârstă de 7 ani: "Tati, știi, m-am gândit că orice întoarcere în timp ca să rezolvi ceva e un paradox. Pentru că dacă te întorci și rezolvi, atunci în prezent nu mai ai niciun motiv să te întorci…"
Proceedings of the National Conference of Thermodynamics with International Participation (NACOT) "Present and Future in Thermodynamics", 2013
In order to study the human cardiovascular system, we develop a Windkessel model of the heart and... more In order to study the human cardiovascular system, we develop a Windkessel model of the heart and the blood vessels. This model can be used to study the time evolution of various thermodynamic parameters, in different regimes of the heart (high blood pressure, low blood pressure, normal blood pressure, high speed, low speed, normal speed etc.). We draw qualitative pressure-volume diagrams in order to apply the Finite Speed Thermodynamics (FST) to this model.
"Considering generic cost functions, we show that minimizing the cost (pump + pipes) of tree-like... more "Considering generic cost functions, we show that minimizing the cost (pump + pipes) of tree-like installations transporting a generic fluid to sinks with given flows and pressures follows two general laws:
1. The pump’s and pipes’ “cost per bar” is conserved in nodes (similarly to the flow).
2. In each Steiner node, the pipes’ cost gradients are in equilibrium.
The resulting configuration is also optimal in another sense: among all the networks with the same cost, this has minimum power dissipation and requires minimum pump pressure/power. Based on these results, we propose a local optimization algorithm which may be responsible for how biological networks (of blood vessels, capillary vessels etc.) minimize their cost. The algorithm takes into account the possible non-homogenous environment."
Lucrările Conferinței Internaționale ZILELE ACADEMICE ale Academiei de Științe Tehnice din România "Viața și activitățile în mari aglomerații urbane. București, prezent și viitor", 2012
Minimizing the cost of tree-like pipe networks at constant dissipated power follows two general l... more Minimizing the cost of tree-like pipe networks at constant dissipated power follows two general laws:
1. The “cost per dissipated watt” ratio is the same for all pipes.
2. In each node, defining along the pipes vectors equal to a certain power of the flow, they are in equilibrium.
The resulting configuration is also optimal in another sense: among all the networks with the same cost, this has minimum power dissipation. Based on these results, we propose a local optimization algorithm which may be responsible for how biological networks (of blood vessels, capillary vessels etc.) minimize their cost.
Zeno's paradox Achilles and the Tortoise shows that among the fundamental postulates regarding sp... more Zeno's paradox Achilles and the Tortoise shows that among the fundamental postulates regarding space, time and motion we have to include the idea that “In every Achillean race there exists a point in which the quicker one meets the slower one.” This idea does not follow from “Between two points there exists another,” and neither from “A moving body cannot get beyond a point without first passing through it”. It is independent and cannot be proved from these intuitions. Without this postulate, the meeting of the two contestants is not guaranteed. It is equivalent to the Completeness Axiom of the real numbers: “Every bounded monotone array has a limit.” Even admitting by axiom its existence, the meeting point cannot be specified finitely – exactly as Zeno says in Achilles and in The Dichotomy. The modern theory of the real numbers, defined by the Completeness Axiom and by the impossibility of finite description, is based on these ideas.
Prisoner's Dilemma is a type of interaction in which the Nash equilibrium does not bring the best... more Prisoner's Dilemma is a type of interaction in which the Nash equilibrium does not bring the best result for neither of the rational agents. The optimal result cannot be reached by way of reason, but can only be imposed from a level transcending the agents' rationality: they obey a common instinct which pushes them to cooperate irrationally. This instinct could be called Honor and, despite a strong temptation to explain it rationally, is not rooted in reason. The beneficiary of this systematic failure of reason is only as a side effect the individual, but it is hard wired in the individual for the benefit of the true replicators: the genes. That's why the Kantian moral rule “Ask yourself: What if everyone did that?...”, although incorrect as logical reasoning, nevertheless has some practical relevance – it can help us distinguish between the “irrational cooperative drive” stemming from our genes and some accidental irrational moods. These phenomena are most visible in situations dubbed “Prisoner's Co-Dilemma” (Prisoner's Dilemma combined with a simple dilemma), frequent in human interactions.
The students reason:" If we will have the test on the last day of the next week (be it Sunda... more The students reason:" If we will have the test on the last day of the next week (be it Sunday), then the previous day (Saturday) we could say:'There was no test either on any of the previous days, or today, so it's for sure we will have the test tomorrow.'But a test that we ...
Abstract: The goals of the paper are: to build a general model of the discussion; to define in a ... more Abstract: The goals of the paper are: to build a general model of the discussion; to define in a clear manner the phenomenon regularly called" dispute"; to define the argument and to build a model of the argumentation; to identify, to classify and to analyze the frequent ...
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Papers by Vlad Enache
1. The pump’s and pipes’ “cost per bar” is conserved in nodes (similarly to the flow).
2. In each Steiner node, the pipes’ cost gradients are in equilibrium.
The resulting configuration is also optimal in another sense: among all the networks with the same cost, this has minimum power dissipation and requires minimum pump pressure/power. Based on these results, we propose a local optimization algorithm which may be responsible for how biological networks (of blood vessels, capillary vessels etc.) minimize their cost. The algorithm takes into account the possible non-homogenous environment."
1. The “cost per dissipated watt” ratio is the same for all pipes.
2. In each node, defining along the pipes vectors equal to a certain power of the flow, they are in equilibrium.
The resulting configuration is also optimal in another sense: among all the networks with the same cost, this has minimum power dissipation. Based on these results, we propose a local optimization algorithm which may be responsible for how biological networks (of blood vessels, capillary vessels etc.) minimize their cost.
Drafts by Vlad Enache
1. The pump’s and pipes’ “cost per bar” is conserved in nodes (similarly to the flow).
2. In each Steiner node, the pipes’ cost gradients are in equilibrium.
The resulting configuration is also optimal in another sense: among all the networks with the same cost, this has minimum power dissipation and requires minimum pump pressure/power. Based on these results, we propose a local optimization algorithm which may be responsible for how biological networks (of blood vessels, capillary vessels etc.) minimize their cost. The algorithm takes into account the possible non-homogenous environment."
1. The “cost per dissipated watt” ratio is the same for all pipes.
2. In each node, defining along the pipes vectors equal to a certain power of the flow, they are in equilibrium.
The resulting configuration is also optimal in another sense: among all the networks with the same cost, this has minimum power dissipation. Based on these results, we propose a local optimization algorithm which may be responsible for how biological networks (of blood vessels, capillary vessels etc.) minimize their cost.