On thermodynamics and the nature of the second law

1977 ◽  
Vol 357 (1690) ◽  
pp. 253-270 ◽  
Keyword(s):  
Mechanical Response ◽  
The Body ◽  
Temperature Fields ◽  
Second Law ◽  
Fading Memory ◽  
New Approach ◽  
Spatially Homogeneous ◽  
Dissipative Material ◽  
Point Of Departure ◽  
Homogeneous Temperature

The contents of this paper represent a new approach to continuum thermo­dynamics and are chiefly concerned with ( a ) a procedure for obtaining restrictions on constitutive equations, ( b ) an appropriate mathematical statement of the second law and ( c ) the nature of restrictions placed by the latter on thermo-mechanical behaviour of single phase continua. Our point of departure is the introduction of a balance of entropy and the use of the energy equation as an identity for all motions and all temperature distributions after the elimination of the external fields. This is in contrast to the approach adopted in most of the current literature on continuum ther­modynamics based on the use of the Clausius-Duhem inequality. In order to gain some insight into the nature of our procedure we first study the case of an elastic material, which includes that of an ideal fluid as a special case, before the consideration of the second law. We then go on to postu­late an inequality which reflects the fact that for every process associated with a dissipative material, a part of the mechanical work is always con­verted into heat and this cannot be withdrawn from the medium as mech­anical work. The restriction on the heat conduction vector is considered separately and is confined to equilibrium cases in which heat flow is steady. A restriction is also obtained for the internal energy when the body is in mechanical equilibrium subjected to spatially homogeneous temperature fields. Using the above approach, next we study the nature of thermodynamic restrictions on the thermo-mechanical response of a viscous fluid and simple materials with fading memory. A drawback to the Clausius-Duhem inequality is discussed by means of an example. For a class of rigid heat conductors in thermal equilibrium, the Clausius-Duhem inequality requires that if heat is added to the medium, the resulting spatially homogeneous temperature of the conductor decreases . Moreover, the in­-equality denies the possibility of propagation of heat in the conductor as a thermal wave with finite speed. The inequalities proposed in this paper do not suffer from these shortcomings.

scholarly journals Mathematical Modeling and Numerical Simulation of Atherosclerosis Based on a Novel Surgeon’s View

2021 ◽  
Author(s):  
Meisam Soleimani ◽  
Axel Haverich ◽  
Peter Wriggers
Keyword(s):  
Mathematical Modeling ◽  
Inflammatory Response ◽  
Phase Field ◽  
Mechanical Response ◽  
Type Equation ◽  
The Body ◽  
Vasa Vasorum ◽  
Diffusion Reaction ◽  
Dust Particles ◽  
Driving Mechanism

AbstractThis paper deals with the mathematical modeling of atherosclerosis based on a novel hypothesis proposed by a surgeon, Prof. Dr. Axel Haverich (Circulation 135(3):205–207, 2017). Atherosclerosis is referred as the thickening of the artery walls. Currently, there are two schools of thoughts for explaining the root of such phenomenon: thickening due to substance deposition and thickening as a result of inflammatory overgrowth. The hypothesis favored here is the second paradigm stating that the atherosclerosis is nothing else than the inflammatory response of of the wall tissues as a result of disruption in wall nourishment. It is known that a network of capillaries called vasa vasorum (VV) accounts for the nourishment of the wall in addition to the natural diffusion of nutrient from the blood passing through the lumen. Disruption of nutrient flow to the wall tissues may take place due to the occlusion of vasa vasorums with viruses, bacteria and very fine dust particles such as air pollutants referred to as PM 2.5. They can enter the body through the respiratory system at the first place and then reach the circulatory system. Hence in the new hypothesis, the root of atherosclerotic vessel is perceived as the malfunction of microvessels that nourish the vessel. A large number of clinical observation support this hypothesis. Recently and highly related to this work, and after the COVID-19 pandemic, one of the most prevalent disease in the lungs are attributed to the atherosclerotic pulmonary arteries, see Boyle and Haverich (Eur J Cardio Thorac Surg 58(6):1109–1110, 2020). In this work, a general framework is developed based on a multiphysics mathematical model to capture the wall deformation, nutrient availability and the inflammatory response. For the mechanical response an anisotropic constitutive relation is invoked in order to account for the presence of collagen fibers in the artery wall. A diffusion–reaction equation governs the transport of the nutrient within the wall. The inflammation (overgrowth) is described using a phase-field type equation with a double well potential which captures a sharp interface between two regions of the tissues, namely the healthy and the overgrowing part. The kinematics of the growth is treated by classical multiplicative decomposition of the gradient deformation. The inflammation is represented by means of a phase-field variable. A novel driving mechanism for the phase field is proposed for modeling the progression of the pathology. The model is 3D and fully based on the continuum description of the problem. The numerical implementation is carried out using FEM. Predictions of the model are compared with the clinical observations. The versatility and applicability of the model and the numerical tool allow.

THE METHOD FOR EVALUATING ADAPTIVE CHANGES IN HUMAN MICROCIRCULATORY-TISSUE SYSTEMS

2020 ◽  
Vol 4 (1) ◽  
pp. 88-99
Author(s):  
A.V. DUNAEV
Keyword(s):  
Middle Finger ◽  
Analysis Data ◽  
The Body ◽  
Tissue Oxygen Saturation ◽  
Doppler Flowmetry ◽  
New Approach ◽  
Adaptive Changes ◽  
Palmar Surface ◽  
Tissue Systems ◽  
The Right

The work is aimed at developing a new approach to assessing adaptive changes in microcirculatory tissue systems when various loads are exerted on the body (sports or physiological stresses), based on the analysis of oscillations in microcirculatory blood flow and tissue oxygen saturation, measured by laser Doppler flowmetry (LDF) and tissue reflectance oximetry (TRO). The study involved eight healthy volunteers aged 21–49 years. Measurements were taken on the palmar surface of the middle finger of the right hand and the medial surface of the lower part of the forearm. The rhythmic oscillations of LDF and TRO were studied using wavelet analysis. Data analysis revealed resonant and synchronized oscillations in the LDF and TRO signals in the myogenic range as an adaptive change as a result of a reaction to physical activity and psychoemotional stress.

scholarly journals Human Machines Petrified: Play's Mineral Mechanics and Les statues meurent aussi

2019 ◽  
Vol 28 (2) ◽  
pp. 179-196
Author(s):  
Olga Beloborodova ◽  
Pim Verhulst
Keyword(s):  
Human Subjects ◽  
The Body ◽  
French Translation ◽  
New Approach ◽  
Life And Death ◽  
Starting Point ◽  
Critical Attention ◽  
Mechanical Devices ◽  
Sentient Beings

Play is usually regarded as the starting point of Beckett's late theatre, introducing a radically new approach to the body and language that set a benchmark for subsequent plays such as Not I, That Time and Footfalls. Building on Krapp's Last Tape and Happy Days, Play dehumanizes its characters by means of the audiovisual technologies that Beckett was experimenting with at the time. In this process, his human subjects are increasingly reduced to mechanical devices or mouthpieces for the conveyance of speech, instead of represented as recognizable and sentient beings of flesh and blood. The nonhuman aspect of Play is enhanced by its foregrounding of Beckett's long-standing fascination with the mineral, with the characters' faces being ‘so lost to age and aspect as to seem almost part of the urns’. Whereas, separately, the influence of radio, television and cinema on Play has received some critical attention, and James Knowlson, Claire Lozier, Mark Nixon, Jean-Michel Rabaté and Conor Carville, among others, have noted Beckett's fascination with the sculptural arts and the inorganic, this paper aims to merge those two strands by discussing the docufilm Les statues meurent aussi (1953) as a potential but overlooked source of inspiration. By combining the technological and the sculptural in Play, Beckett stages a ‘mineral mechanics’ verging closely on the nonhuman without being fully dehumanized, as characters continue to laugh and hiccup, barely retaining a trace of their humanity. This oscillation from the human to the nonhuman and vice versa is clearly traceable in the genesis of the text, as well as its French translation (Comédie). The result, Play's iconic stage image, is marked by the familiar Beckettian trope of in-betweenness: between life and death, between the organic and the mineral, between the natural and the technological.

order to answer this question, we should obviouslyexamine Weyer's Depraestigiis to see if it contains elements of what is called, perhaps inappropriately, a myth. One of my students researched this and provided me with the results . She demonstrated that Johann Weyer was nowhere presented as one who opposed the theological approach by means of a medical approach. Admittedly, he pointed to certain 'somatic' causes which affected the physical constitution of witches and which predisposed them to be influenced by the peculiar materiality of the devil's 'spirit'. Weyer even spoke of 'melancholia' when he described the specificsomatic constitution of the witches. But in this he did not differ from the philosophers, theologians and physicians of his time. The same can be argued regarding the second element of the myth. Certainly, Weyer pleaded for a humanitarian approach and acted courageously against unnecessary cruelty , as Montaigne and others did. However, does this imply that he was defending an approach which foreshadowed the specific psychiatric practice? I find it impossible to draw this conclusion. Nevertheless, the debate around witch-hunting was of historical significance for modern times because of the changes which it introduced in the Western concept of man. More elements are involved than are usually related in the traditional Weyer myth. The witch-hunt period was also the period during which the disciplines of theology and philosophy started to diverge. The Reformation and the subsequent wars of religion were partly responsible for this development. It was also influenced by the new findings in lruman biology. Around that time, the circulatory system was discovered. One had also become aware of the existence and importance of the nervous system, although its precise way of functioning was not yet fully understood. The theory of physiological humours was being gradually discarded and, along with it, the belief in 'spirits', the very tiny but distinct material elements in the body's centre. The manner in which Descartes, for example, attempted to construct a. theory of the blood's circuiation which did not abandon the belief in these material spirits, demonstrates how difficult was for modern thought to leave the old experience of the body behind. Moreover, religion was linked to this bodily experience. The beliefs that a human being was part of the harmony of creation, that mankind was influenced by the cosmos, that all kinds of spirits existed; the moral consequences derived from these key beliefs and the more particular religious statements such as, for example, transubstantiation as the core of the Eucharist, were shaken by the new conceptions of the human body which focused on 'man as a machine'. It is characteristic of the changes in this period that the Church did not attack Descartes's philosophical system for its sceptical point of departure. At that time, scepticism was an attitude favoured

2013 ◽  
pp. 157-157
Keyword(s):  
Circulatory System ◽  
The Body ◽  
Wars Of Religion ◽  
Historical Significance ◽  
New Findings ◽  
The Reformation ◽  
The Witch ◽  
Witch Hunt ◽  
Theology And Philosophy ◽  
Point Of Departure

Thermodynamics From a Few Dynamic Particles Raises Questions as to How Temperature and Entropy Should Be Perceived and Defined

2007 ◽  
Author(s):  
W. John Dartnall ◽  
John Reizes
Keyword(s):  
Kinetic Energy ◽  
Single Particle ◽  
Heat Engine ◽  
Working Fluid ◽  
Second Law ◽  
Piston Engine ◽  
New Approach ◽  
Particle Mechanics ◽  
Mechanics Model ◽  
Heat Engines

In a recently developed simple particle mechanics model, in which a single particle represents the working fluid, (gas) in a heat engine, (exemplified by a piston engine) a new approach was outlined for the teaching of concepts to thermodynamic students. By mechanics reasoning, a model was developed that demonstrates the connection between the Carnot efficiency limitation of heat engines, and the Kelvin-Planck statement of Second Law, requiring only the truth of the Clausius statement. In a second paper the model was extended to introduce entropy. The particle’s entropy was defined as a function of its kinetic energy, and the space that it occupies, that is analogous to that normally found in classical macroscopic analyses. In this paper, questions are raised and addressed: How should temperature and entropy be perceived and defined? Should temperature be proportional to average (molecular) translational kinetic energy and should entropy be dimensionless?

scholarly journals Assessing the Impact of Oil Types and Grades on Tocopherol and Tocotrienol Contents in Vegetable Oils with Chemometric Methods

Molecules ◽  
2020 ◽  
Vol 25 (21) ◽  
pp. 5076
Author(s):  
Yunqi Wen ◽  
Lili Xu ◽  
Changhu Xue ◽  
Xiaoming Jiang ◽  
Zihao Wei
Keyword(s):  
Vegetable Oil ◽  
Vegetable Oils ◽  
Edible Oils ◽  
The Body ◽  
New Approach ◽  
Sunflower Oils ◽  
Sacha Inchi Oil ◽  
Sacha Inchi ◽  
Oil Refinement ◽  
The Impact

The consumption of vegetable oil is an important way for the body to obtain tocols. However, the impact of oil types and grades on the tocopherol and tocotrienol contents in vegetable oils is unclear. In this study, nine types of traditional edible oils and ten types of self-produced new types of vegetable oil were used to analyze eight kinds of tocols. The results showed that the oil types exerted a great impact on the tocol content of traditional edible oils. Soybean oils, corn oils, and rapeseed oils all could be well distinguished from sunflower oils. Both sunflower oils and cotton seed oils showed major differences from camellia oils as well as sesame oils. Among them, rice bran oils contained the most abundant types of tocols. New types of oil, especially sacha inchi oil, have provided a new approach to obtaining oils with a high tocol content. Oil refinement leads to the loss of tocols in vegetable oil, and the degree of oil refinement determines the oil grade. However, the oil grade could not imply the final tocol content in oil from market. This study could be beneficial for the oil industry and dietary nutrition.

Processing Considerations for Salicylic Acid-Based Polymers

2003 ◽  
Author(s):  
Eva Wagner ◽  
Kathryn Uhrich ◽  
Thomas Twardowski
Keyword(s):  
Salicylic Acid ◽  
Controlled Release ◽  
Temperature Dependence ◽  
Medical Devices ◽  
Melt Processing ◽  
The Body ◽  
Hollow Fibers ◽  
New Approach ◽  
Degradable Polymer ◽  
Solution Spinning

This paper describes some of the processing issues for extruding salicylic acid-based polymer prodrugs into fibers for medical devices. Polymeric prodrugs, in which a drug is polymerized in a degradable polymer that delivers controlled quantity of the drug to a targeted site in the body as the device degrades, are a new approach to controlled release. Hollow fibers were produced by solution spinning. Solid fibers were formed by melt processing. The salicylic acid polymers exhibited shear-thinning behavior. The viscosity exhibited pronounced temperature dependence.

A New Approach for Body Balance of a Humanoid Robot

2014 ◽  
Vol 6 (4) ◽  
pp. 33-46
Author(s):  
Ory Medina ◽  
Daniel Madrigal ◽  
Félix Ramos ◽  
Gustavo Torres ◽  
Marco Ramos
Keyword(s):  
Vestibular System ◽  
Humanoid Robot ◽  
The Body ◽  
Motor Output ◽  
Motor Systems ◽  
New Approach ◽  
Proposed Model ◽  
Physical Tests ◽  
Proprioceptive Inputs ◽  
Visual Gaze

In humans, the vestibular system along with other sensory and motor systems is responsible for three cognitive functions that support mobility. First, is responsible for the balance of the body. Second, it allows humans to maintain the head stabilized. Finally, whenever the body or head are in motion, it maintains the visual gaze on a desired target. These tasks are performed using an array of sensors that are located within the inner ear. This paper describes the design and implementation of a synthetic model of the human vestibular system. The model is based on neurophysiological evidence, which makes it necessary to model all of the neural and physical components involved in the balance of the body. The model includes a component for each of the sensors, cortical and subcortical neural structures. It also defines and generates the necessary motor output signals. The proposed model was connected to a Bioloid® Premium humanoid robot to simulate the motor output and the proprioceptive inputs. The physical tests resulted inconclusive due to the fact that the controller on the robot was incapable of handling the necessary information for the tests. However, even though the results were not the desired, the communication between the sensors and the architecture, as well as the processing inside the architecture satisfied all of the authors' expectations.

Sign in / Sign up

Export Citation Format

Share Document