0
Your cart

Your cart is empty

Browse All Departments
Price
  • R100 - R250 (3)
  • R250 - R500 (36)
  • R500+ (1,907)
  • -
Status
Format
Author / Contributor
Publisher

Books > Science & Mathematics > Physics > Thermodynamics & statistical physics > Thermodynamics

Mechanothermodynamics (Hardcover, 1st ed. 2016): Leonid Sosnovskiy, Sergei Sherbakov Mechanothermodynamics (Hardcover, 1st ed. 2016)
Leonid Sosnovskiy, Sergei Sherbakov
R1,411 Discovery Miles 14 110 Ships in 18 - 22 working days

This monograph addresses the foundations of mechanothermodynamics and analyzes two of its key principles-damage of everything that exists has no conceivable limits, and effective energy (entropy) flows caused by loads of a different nature do not have a cumulative property; they interact dialectically. The authors examine a generalized model of energy and entropy states of a mechanothermodynamical medium, which generally is a continuum (liquid, gaseous) containing distributed solid deformable, and, therefore, damageable bodies, as a problem of information states of movable and damageable systems and express a solution in the first approximation. The book goes on to analyze some directions of further research in its conclusion. It is ideal for scientists, engineers, post graduate and master students of mechanics, mathematics and physics.

Microcontinuum Field Theories - II. Fluent Media (Hardcover, 2001 ed.): A. Cemal Eringen Microcontinuum Field Theories - II. Fluent Media (Hardcover, 2001 ed.)
A. Cemal Eringen
R4,201 Discovery Miles 42 010 Ships in 18 - 22 working days

Microcontinuum Field Theories constitutes an extension of classical field theories - of elastic solids, viscous fluids, electromagnetism, and the like - to microscopic length and time scales. Material bodies are viewed as collections of a large number of deformable particles (sub-continua), suitable for modeling blood, porous media, polymers, liquid crystals, slurries, and composite materials. This volume extends and applies the ideas developed in the first volume, Microcontinuum Field Theories: Foundations and Solids, to liquid crystals, biological fluids, and other microstretch and micomorphic fluids. The theory makes it possible to discuss properties of such materials that are beyond the scope of classical field theories and may provide a basis for the resolution of some outstanding problems, such as turbulence.

Non-equilibrium Energy Transformation Processes - Theoretical Description at the Level of Molecular Structures (Hardcover, 2014... Non-equilibrium Energy Transformation Processes - Theoretical Description at the Level of Molecular Structures (Hardcover, 2014 ed.)
Viktor Holubec
R2,661 Discovery Miles 26 610 Ships in 18 - 22 working days

Various experimental techniques have been advanced in recent years to measure non-equilibrium energy transformations on themicroscopic scale of single molecules. In general, the systems studied inthe correspondingexperiments are exposed to strong thermal fluctuations and thus the relevant energetic variables such as work and heat become stochastic.

This thesis addresses challenging theoretical problems in this active field of current research: 1) Exact analytical solutions of work and heat distributions for isothermal non-equilibrium processes in suitable models are obtained; 2) Corresponding solutions for cyclic processes involving two different heat reservoirs are found; 3) Optimization of periodic driving protocols for such cyclic processes with respect to maximal output power, efficiency and minimal power fluctuations is studied.

The exact solutions for work and heat distributionsprovide areference for theoretical investigations of more complicated models, giving insight into the structure of the tail of work distributions andserving asvaluable test cases for simulations of the underlying stochastic processes."

Thermal Elastic  Mechanics Problems of Concrete Rectangular Thin Plate (Hardcover, 1st ed. 2018): Xuansheng Cheng Thermal Elastic Mechanics Problems of Concrete Rectangular Thin Plate (Hardcover, 1st ed. 2018)
Xuansheng Cheng
R3,855 R3,324 Discovery Miles 33 240 Save R531 (14%) Ships in 10 - 15 working days

This book discusses the thermal-elastic mechanics problems of concrete rectangular thin plate. Using theoretical derivation combined with numerical examples, it explains in detail the analytical solution of the deflection, bending moment, thermal vibration and thermal buckling of concrete rectangular thin plate. To facilitate application, the book also includes deflection and bending moment calculation tables of concrete rectangular thin plate with four edges supported and with free boundary conditions.

Advances in Heat Transfer, Volume 46 (Hardcover): Ephraim M. Sparrow, John Patrick Abraham, John M Gorman, Young I. Cho Advances in Heat Transfer, Volume 46 (Hardcover)
Ephraim M. Sparrow, John Patrick Abraham, John M Gorman, Young I. Cho
R4,658 Discovery Miles 46 580 Ships in 10 - 15 working days

Advances in Heat Transfer fills the information gap between regularly scheduled journals and university-level textbooks by providing in-depth review articles over a broader scope than in journals or texts. The articles, which serve as a broad review for experts in the field, will also be of great interest to non-specialists who need to keep up-to-date with the results of the latest research. This serial is essential reading for all mechanical, chemical and industrial engineers working in the field of heat transfer, graduate schools or industry.

Asymptotic Safety and Black Holes (Hardcover, 2013 ed.): Kevin Falls Asymptotic Safety and Black Holes (Hardcover, 2013 ed.)
Kevin Falls
R4,099 R3,298 Discovery Miles 32 980 Save R801 (20%) Ships in 10 - 15 working days

One of the open challenges in fundamental physics is to combine Einstein's theory of general relativity with the principles of quantum mechancis. In this thesis, the question is raised whether metric quantum gravity could be fundamental in the spirit of Steven Weinberg's seminal asymptotic safety conjecture, and if so, what are the consequences for the physics of small, possibly Planck-size black holes? To address the first question, new techniques are provided which allow, for the first time, a self-consistent study of high-order polynomial actions including up to 34 powers in the Ricci scalar. These novel insights are then exploited to explain quantum gravity effects in black holes, including their horizon and causal structure, conformal scaling, evaporation, and the thermodynamics of quantum space-time. Results indicate upper limits on black hole temperature, and the existence of small black holes based on asymptotic safety for gravity and thermodynamical arguments.

Advances in Transport Phenomena 2011 (Hardcover, 2014 ed.): Liqiu Wang Advances in Transport Phenomena 2011 (Hardcover, 2014 ed.)
Liqiu Wang
R3,533 R3,273 Discovery Miles 32 730 Save R260 (7%) Ships in 10 - 15 working days

This new volume of the annual review "Advances in Transport Phenomena" series contains three in-depth review articles on the microfluidic fabrication of vesicles, the dielectrophoresis field-flow fractionation for continuous-flow separation of particles and cells in microfluidic devices, and the thermodynamic analysis and optimization of heat exchangers, respectively.

New Insights Into Heat Transfer (Hardcover): Nathan Rice New Insights Into Heat Transfer (Hardcover)
Nathan Rice
R2,125 Discovery Miles 21 250 Ships in 10 - 15 working days
Formulation of Uncertainty Relation Between Error and Disturbance in Quantum Measurement by Using Quantum Estimation Theory... Formulation of Uncertainty Relation Between Error and Disturbance in Quantum Measurement by Using Quantum Estimation Theory (Hardcover, 2014 ed.)
Yu Watanabe
R2,768 R1,773 Discovery Miles 17 730 Save R995 (36%) Ships in 10 - 15 working days

In this thesis, quantum estimation theory is applied to investigate uncertainty relations between error and disturbance in quantum measurement. The author argues that the best solution for clarifying the attainable bound of the error and disturbance is to invoke the estimation process from the measurement outcomes such as signals from a photodetector in a quantum optical system. The error and disturbance in terms of the Fisher information content have been successfully formulated and provide the upper bound of the accuracy of the estimation. Moreover, the attainable bound of the error and disturbance in quantum measurement has been derived. The obtained bound is determined for the first time by the quantum fluctuations and correlation functions of the observables, which characterize the non-classical fluctuation of the observables. The result provides the upper bound of our knowledge obtained by quantum measurements. The method developed in this thesis will be applied to a broad class of problems related to quantum measurement to build a next-generation clock standard and to successfully detect gravitational waves.

Optimal Control in Thermal Engineering (Hardcover, 1st ed. 2017): Viorel Badescu Optimal Control in Thermal Engineering (Hardcover, 1st ed. 2017)
Viorel Badescu
R5,254 Discovery Miles 52 540 Ships in 18 - 22 working days

This book is the first major work covering applications in thermal engineering and offering a comprehensive introduction to optimal control theory, which has applications in mechanical engineering, particularly aircraft and missile trajectory optimization. The book is organized in three parts: The first part includes a brief presentation of function optimization and variational calculus, while the second part presents a summary of the optimal control theory. Lastly, the third part describes several applications of optimal control theory in solving various thermal engineering problems. These applications are grouped in four sections: heat transfer and thermal energy storage, solar thermal engineering, heat engines and lubrication.Clearly presented and easy-to-use, it is a valuable resource for thermal engineers and thermal-system designers as well as postgraduate students.

Researcher's Guide to Heat Conduction (Hardcover): Edgar Miller Researcher's Guide to Heat Conduction (Hardcover)
Edgar Miller
R3,238 R2,928 Discovery Miles 29 280 Save R310 (10%) Ships in 18 - 22 working days
Thermodynamics for Chemists, Physicists and Engineers (Hardcover, 2012): Robert Holyst, Andrzej Poniewierski Thermodynamics for Chemists, Physicists and Engineers (Hardcover, 2012)
Robert Holyst, Andrzej Poniewierski
R2,228 Discovery Miles 22 280 Ships in 10 - 15 working days

This textbook takes an interdisciplinary approach to the subject of thermodynamics and is therefore suitable for undergraduates in chemistry, physics and engineering courses. The book is an introduction to phenomenological thermodynamics and its applications to phase transitions and chemical reactions, with some references to statistical mechanics. It strikes the balance between the rigorousness of the Callen text and phenomenological approach of the Atkins text. The book is divided in three parts. The first introduces the postulates and laws of thermodynamics and complements these initial explanations with practical examples. The second part is devoted to applications of thermodynamics to phase transitions in pure substances and mixtures. The third part covers thermodynamic systems in which chemical reactions take place. There are some sections on more advanced topics such as thermodynamic potentials, natural variables, non-ideal mixtures and electrochemical reactions, which make this book of suitable also to post-graduate students.

Technology and Applied Principles of Heat Transfer (Hardcover): Nathan Rice Technology and Applied Principles of Heat Transfer (Hardcover)
Nathan Rice
R3,142 R2,845 Discovery Miles 28 450 Save R297 (9%) Ships in 18 - 22 working days
Thermal Quantum Field Theory and Perturbative Non-Equilibrium Dynamics (Hardcover, 2014 ed.): Peter Millington Thermal Quantum Field Theory and Perturbative Non-Equilibrium Dynamics (Hardcover, 2014 ed.)
Peter Millington
R4,142 R3,341 Discovery Miles 33 410 Save R801 (19%) Ships in 10 - 15 working days

The author develops a new perturbative formalism of non-equilibrium thermal quantum field theory for non-homogeneous backgrounds. As a result of this formulation, the author is able to show how so-called pinch singularities can be removed, without resorting to ad hoc prescriptions, or effective resummations of absorptive effects. Thus, the author arrives at a diagrammatic approach to non-equilibrium field theory, built from modified Feynman rules that are manifestly time-dependent from tree level. This new formulation provides an alternative framework in which to derive master time evolution equations for physically meaningful particle number densities, which are valid to all orders in perturbation theory and to all orders in gradient expansion. Once truncated in a loop-wise sense, these evolution equations capture non-equilibrium dynamics on all time-scales, systematically describing energy-violating processes and the non-Markovian evolution of memory effects

Theory Of Thermoluminescence And Related Phenomena (Hardcover): Reuven. Chen, Stephen W.S. McKeever Theory Of Thermoluminescence And Related Phenomena (Hardcover)
Reuven. Chen, Stephen W.S. McKeever
R2,942 Discovery Miles 29 420 Ships in 10 - 15 working days

In this book, the authors give an up-to-date account of thermoluminescence (TL) and other thermally stimulated phenomena. Although most recent experimental results of TL in different materials are described in some detail, the main emphasis in the present book is on general processes, and the approach is more theoretical. Thus the details of the possible processes which can take place during the excitation of the sample, and during its heating, are carefully analysed. The methods for analysing TL glow curves are critically discussed, and recommendations as to their application are made. Also discussed is the expected behavior of these phenomena as functions of the experimental parameters, for example, dose of excitation. The consequences of the main applications of TL (for example, radiation dosimetry) are also discussed in detail as are the similarities and dissimilarities of other thermally stimulated phenomena, and the simultaneous measurements of the latter and TL.

The Energetics of Computing in Life and Machines (Hardcover): David H. Wolpert, Chris Kempes, Peter F. Stadler The Energetics of Computing in Life and Machines (Hardcover)
David H. Wolpert, Chris Kempes, Peter F. Stadler
R807 Discovery Miles 8 070 Ships in 18 - 22 working days
Entropy And The Second Law: Interpretation And Misss-interpretationsss (Hardcover): Arieh Ben-Naim Entropy And The Second Law: Interpretation And Misss-interpretationsss (Hardcover)
Arieh Ben-Naim
R1,252 Discovery Miles 12 520 Ships in 10 - 15 working days

This book presents a clear and readable description of one of the most mysterious concepts of physics: Entropy. It contains a self-learning kit that guides the reader in understanding the concepts of entropy. In the first part, the reader is asked to play the familiar twenty-Question game. Once the reader feels comfortable with playing this game and acquires proficiency in playing the game effectively (intelligently), he or she will be able to capture the elusive and used-to-be mysterious concept of entropy.There will be no more speculative or arbitrary interpretations, nor "older" or "modern" views of entropy. This book will guide readers in choosing their own interpretation of entropy.

Professor I. I. Glass: A Tribute and Memorial (Hardcover, 2013 ed.): Kazuyoshi Takayama, Ozer Igra Professor I. I. Glass: A Tribute and Memorial (Hardcover, 2013 ed.)
Kazuyoshi Takayama, Ozer Igra
R2,658 Discovery Miles 26 580 Ships in 18 - 22 working days

The book provides personal memories along with description of scientific works written by ex-graduate students and research associates of the late Professor Glass. The described research work covers a wide range of shock wave phenomena, resulting from seeds planted by Professor Glass. Professor Glass was born in Poland in 1918. He immigrated together with his parents to Canada at the age of 12 and received all his professional education at the University of Toronto, Canada. He became a world recognized expert in shock wave phenomena, and during his 45 years of active research he supervised more than 125 master and doctoral students, post-doctoral fellows and visiting research associates. In this book seven of his past students/research-associates describe their personal memories of Professor Glass and present some of their investigations in shock wave phenomena which sprung from their past work with Professor Glass. Specifically, these investigations include underwater shock waves, shock/bubble interaction, medical applications of shock wave, various types of shock tubes and shock tube techniques, shock wave attenuation and different types of shock wave reflections.

An Introduction to Statistical Mechanics and Thermodynamics (Hardcover): Robert H. Swendsen An Introduction to Statistical Mechanics and Thermodynamics (Hardcover)
Robert H. Swendsen
R2,183 Discovery Miles 21 830 Ships in 10 - 15 working days

This text presents the two complementary aspects of thermal physics as an integrated theory of the properties of matter. Conceptual understanding is promoted by thorough development of basic concepts. In contrast to many texts, statistical mechanics, including discussion of the required probability theory, is presented first. This provides a statistical foundation for the concept of entropy, which is central to thermal physics. A unique feature of the book is the development of entropy based on Boltzmann's 1877 definition; this avoids contradictions or ad hoc corrections found in other texts. Detailed fundamentals provide a natural grounding for advanced topics, such as black-body radiation and quantum gases. An extensive set of problems (solutions are available for lecturers through the OUP website), many including explicit computations, advance the core content by probing essential concepts. The text is designed for a two-semester undergraduate course but can be adapted for one-semester courses emphasizing either aspect of thermal physics. It is also suitable for graduate study.

Irreversibility and Dissipation in Microscopic Systems (Hardcover, 2014 ed.): Edgar Roldan Irreversibility and Dissipation in Microscopic Systems (Hardcover, 2014 ed.)
Edgar Roldan
R4,134 R3,333 Discovery Miles 33 330 Save R801 (19%) Ships in 10 - 15 working days

After an insightful introductory part on recent developments in the thermodynamics of small systems, the author presents his contribution to a long-standing problem, namely the connection between irreversibility and dissipation. He develops a method based on recent results on fluctuation theorems that is able to estimate dissipation using only information acquired in a single, sufficiently long, trajectory of a stationary nonequilibrium process. This part ends with a remarkable application of the method to the analysis of biological data, in this case, the fluctuations of a hair bundle.

The third part studies the energetics of systems that undergo symmetry breaking transitions. These theoretical ideas lead to, among other things, an experimental realization of a Szilard engine using manipulated colloids.

This work has the potential for important applications ranging from the analysis of biological media to the design of novel artificial nano-machines.

Quasi-Geostrophic Theory of Oceans and Atmosphere - Topics in the Dynamics and Thermodynamics of the Fluid Earth (Hardcover,... Quasi-Geostrophic Theory of Oceans and Atmosphere - Topics in the Dynamics and Thermodynamics of the Fluid Earth (Hardcover, 2013 ed.)
Fabio Cavallini, Fulvio Crisciani
R2,709 Discovery Miles 27 090 Ships in 18 - 22 working days

Large-scale winds and currents tend to balance Coriolis and pressure gradient forces. The time evolution of these winds and currents is the subject of the quasi-geostrophic theory.
Chapter 1 presents concepts and equations of classical inertial fluid mechanics.
Chapter 2 deals with the equations of thermodynamics that close the governing equations of the fluids. Then, the motion is reformulated in a uniformly rotating reference frame.
Chapter 3 deals with the shallow-water model and the homogeneous model of wind-driven circulation. The chapter also describes a classical application of the Ekman layer to the atmosphere.
Chapter 4 considers the two-layer model, as an introduction to baroclinic flows, together with the concept of available potential energy.
Chapter 5 takes into account continuously stratified flows in the ocean and in the atmosphere.

Thermodynamics of Fluids Under Flow (Hardcover, 2nd ed. 2011): David Jou, Jose Casas-Vazquez, Manuel Criado-Sancho Thermodynamics of Fluids Under Flow (Hardcover, 2nd ed. 2011)
David Jou, Jose Casas-Vazquez, Manuel Criado-Sancho
R2,821 Discovery Miles 28 210 Ships in 18 - 22 working days

This is the second edition of the book "Thermodynamics of Fluids under Flow," which was published in 2000 and has now been corrected, expanded and updated. This is a companion book to our other title Extended irreversible thermodynamics (D. Jou, J. Casas-Vazquez and G. Lebon, Springer, 4th edition 2010), and of the textbook Understanding non-equilibrium thermodynamics (G. Lebon, D. Jou and J. Casas-Vazquez, Springer, 2008. The present book is more specialized than its counterpart, as it focuses its attention on the non-equilibrium thermodynamics of flowing fluids, incorporating non-trivial thermodynamic contributions of the flow, going beyond local equilibrium theories, i.e., including the effects of internal variables and of external forcing due to the flow. Whereas the book's first edition was much more focused on polymer solutions, with brief glimpses into ideal and real gases, the present edition covers a much wider variety of systems, such as: diluted and concentrated polymer solutions, polymer blends, laminar and turbulent superfluids, phonon hydrodynamics and heat transport in nanosystems, nuclear collisions, far-from-equilibrium ideal gases, and molecular solutions. It also deals with a variety of situations, emphasizing the non-equilibrium flow contribution: temperature and entropy in flowing ideal gases, shear-induced effects on phase transitions in real gases and on polymer solutions, stress-induced migration and its application to flow chromatography, Taylor dispersion, anomalous diffusion in flowing systems, the influence of the flow on chemical reactions, and polymer degradation. The new edition is not only broader in scope, but more educational in character, and with more emphasis on applications, in keeping with our times. It provides many examples of how a deeper theoretical understanding may bring new and more efficient applications, forging links between theoretical progress and practical aims. This updated version expands on the trusted content of its predecessor, making it more interesting and useful for a larger audience."

Free Convection Film Flows and Heat Transfer - Models of Laminar Free Convection with Phase Change for Heat and Mass Transfer... Free Convection Film Flows and Heat Transfer - Models of Laminar Free Convection with Phase Change for Heat and Mass Transfer Analysis (Hardcover, 2nd ed. 2012)
Deyi Shang
R4,113 Discovery Miles 41 130 Ships in 18 - 22 working days

This book presents recent developments in our systematic studies of hydrodynamics and heat and mass transfer in laminar free convection, accelerating film boiling and condensation of Newtonian fluids, as well as accelerating film flow of non-Newtonian power-law fluids (FFNF). These new developments provided in this book are (i) novel system of analysis models based on the developed New Similarity Analysis Method; (ii) a system of advanced methods for treatment of gas temperature- dependent physical properties, and liquid temperature- dependent physical properties; (iii) the organically combined models of the governing mathematical models with those on treatment model of variable physical properties; (iv) rigorous approach of overcoming a challenge on accurate solution of three-point boundary value problem related to two-phase film boiling and condensation; and (v) A pseudo-similarity method of dealing with thermal boundary layer of FFNF for greatly simplifies the heat-transfer analysis and numerical calculation. A system of practical application equations on heat and mass transfer are provided in each chapter, which are formulated based on the rigorous numerical solutions with consideration of variable physical properties. In addition, in the second edition, other new research developments are further included on resolving an even big challenge associated with investigations of laminar free film condensation of vapour-gas mixture. They involve the novel methods for treatment of concentration- and temperature- dependent physical properties of vapour-gas mixture, and for rigorous solution of interfacial vapour saturation temperature, which have lead to rigorous analysis and calculation results on two-phase film flow velocity, temperature, and concentration fields, as well as condensate heat and mass transfer.

Heat Waves (Hardcover, 2011 ed.): Brian Straughan Heat Waves (Hardcover, 2011 ed.)
Brian Straughan
R4,025 Discovery Miles 40 250 Ships in 18 - 22 working days

This book surveys significant modern contributions to the mathematical theories of generalized heat wave equations. The first three chapters form a comprehensive survey of most modern contributions also describing in detail the mathematical properties of each model. Acceleration waves and shock waves are the focus in the next two chapters. Numerical techniques, continuous data dependence, and spatial stability of the solution in a cylinder, feature prominently among other topics treated in the following two chapters. The final two chapters are devoted to a description of selected applications and the corresponding formation of mathematical models. Illustrations are taken from a broad range that includes nanofluids, porous media, thin films, nuclear reactors, traffic flow, biology, and medicine, all of contemporary active technological importance and interest. This book will be of value to applied mathematicians, theoretical engineers and other practitioners who wish to know both the theory and its relevance to diverse applications.

Drying and Energy Technologies (Hardcover, 1st ed. 2016): J.M.P.Q. Delgado, A. Gilson Barbosa de Lima Drying and Energy Technologies (Hardcover, 1st ed. 2016)
J.M.P.Q. Delgado, A. Gilson Barbosa de Lima
R4,134 R3,333 Discovery Miles 33 330 Save R801 (19%) Ships in 10 - 15 working days

This book provides a comprehensive overview of essential topics related to conventional and advanced drying and energy technologies, especially motivated by increased industry and academic interest. The main topics discussed are: theory and applications of drying, emerging topics in drying technology, innovations and trends in drying, thermo-hydro-chemical-mechanical behaviors of porous materials in drying, and drying equipment and energy. Since the topics covered are inter-and multi-disciplinary, the book offers an excellent source of information for engineers, energy specialists, scientists, researchers, graduate students, and leaders of industrial companies. This book is divided into several chapters focusing on the engineering, science and technology applied in essential industrial processes used for raw materials and products.

Free Delivery
Pinterest Twitter Facebook Google+
You may like...
Na 'n Plaas In Afrika
Irma Joubert Paperback R390 R366 Discovery Miles 3 660
The Spy Coast
Tess Gerritsen Paperback R395 R353 Discovery Miles 3 530
Advances in Ecological Research, Volume…
Hal Caswell Hardcover R4,671 Discovery Miles 46 710
Buried In The Chest
Lindani Mbunyuza-Memani Paperback R260 R240 Discovery Miles 2 400
Insecticides Soil Microbiota…
Maddela Naga Raju, Kadiyala Venkateswarlu Hardcover R2,653 Discovery Miles 26 530
The Wish
Nicholas Sparks Paperback R383 Discovery Miles 3 830
Applications of 5G and Beyond in Smart…
Ambar Bajpai, Arun Balodi Hardcover R3,634 Discovery Miles 36 340
Global Information Technology…
Candace Deans, Kirk Karwan Hardcover R1,282 Discovery Miles 12 820
Sliding Mode in Intellectual Control and…
Vardan Mkrttchian, Ekaterina Aleshina Hardcover R3,515 Discovery Miles 35 150
General Systemology…
David Rousseau, Jennifer Wilby, … Hardcover R3,083 Discovery Miles 30 830

 

Partners