Development and Application of a Simulation Tool for Biomass Gasification Based Processes

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Tobias Pröll ◽  
Hermann Hofbauer
Keyword(s):  
Background Information ◽  
Simulation Tool ◽  
Water Steam ◽  
Organic Mixtures ◽  
Ideal Gases ◽  
Dual Fluidized Bed ◽  
Modelling Environment ◽  
Model Equations ◽  
Key Aspects ◽  
Energy Balances

A simulation tool for gasification based processes is presented for an equation-oriented, steady state modelling environment. The approach aims at an adequate description of phenomena linked to gasification. Background information is provided regarding the structure of the framework, thermodynamic data processing, and on the formulation of the model equations. The implemented substance streams are water/steam, ideal gases, inorganic solids, and organic mixtures. The models are based upon mass and energy balances and feature thermodynamic considerations. The addition of correlations for fluid dynamics or chemical kinetics is generally possible but not within the focus of this paper. The key-aspects of the typical unit-models, like pumps, turbines, heat exchangers, separators and chemical reactors are highlighted. The model of a dual-fluidized bed biomass gasifier is presented in detail. In a final case study, the suitability of the simulation tool is demonstrated for the description of the gasification-based biomass combined heat and power plant in Güssing/Austria.

Dizziness

2021 ◽  
Author(s):  
Kevin A. Kerber ◽  
Robert W. Baloh
Keyword(s):  
Vestibular System ◽  
Clinical Medicine ◽  
Background Information ◽  
History Taking ◽  
Symptom Presentation ◽  
Anatomy And Physiology ◽  
Common Causes ◽  
History Of ◽  
Specific Disorders ◽  
Key Aspects

Dizziness is the quintessential symptom presentation in all of clinical medicine. It is a common reason that patients present to a physician. This chapter provides background information about the vestibular system, then reviews key aspects of history-taking and examination of the patient, then discusses specific disorders and common presentation types. Throughout the chapter the focus is on neurologic and vestibular disorders. Normal vestibular anatomy and physiology are discussed, followed by recommendations for history-taking and the physical examination. Specific disorders that cause dizziness are explored, along with common causes of non-specific dizziness. Common presentations are discussed, including acute severe dizziness, recurrent attacks, and recurrent positional vertigo. Finally, the chapter looks at laboratory investigations in diagnosis and management. Figures include population prevalence of dizziness symptoms, the anatomy of inner structures, primary afferent vestibular nerve activity, the head thrust test, the Dix-Hallpike maneuver, the supine positional test, the canalith repositioning procedure, and the barbecue roll maneuver. Tables list physiologic properties and clinical features of the components of the peripheral vestibular system, information to be acquired from history of the present illness, common symptoms patients report as dizziness, examination components, distinguishing among common peripheral and central vertigo syndromes, common causes of nonspecific dizziness, types of dizziness presentations, relevant imaging abnormalities on neuroimaging studies, vestibular testing components, and medical therapy for symptomatic dizziness. This review contains 8 highly rendered figures, 11 tables, and 69 references.

Dizziness

2021 ◽  
Author(s):  
Kevin A. Kerber ◽  
Robert W. Baloh
Keyword(s):  
Vestibular System ◽  
Clinical Medicine ◽  
Background Information ◽  
History Taking ◽  
Symptom Presentation ◽  
Anatomy And Physiology ◽  
Common Causes ◽  
History Of ◽  
Specific Disorders ◽  
Key Aspects

Dizziness is the quintessential symptom presentation in all of clinical medicine. It is a common reason that patients present to a physician. This chapter provides background information about the vestibular system, then reviews key aspects of history-taking and examination of the patient, then discusses specific disorders and common presentation types. Throughout the chapter the focus is on neurologic and vestibular disorders. Normal vestibular anatomy and physiology are discussed, followed by recommendations for history-taking and the physical examination. Specific disorders that cause dizziness are explored, along with common causes of non-specific dizziness. Common presentations are discussed, including acute severe dizziness, recurrent attacks, and recurrent positional vertigo. Finally, the chapter looks at laboratory investigations in diagnosis and management. Figures include population prevalence of dizziness symptoms, the anatomy of inner structures, primary afferent vestibular nerve activity, the head thrust test, the Dix-Hallpike maneuver, the supine positional test, the canalith repositioning procedure, and the barbecue roll maneuver. Tables list physiologic properties and clinical features of the components of the peripheral vestibular system, information to be acquired from history of the present illness, common symptoms patients report as dizziness, examination components, distinguishing among common peripheral and central vertigo syndromes, common causes of nonspecific dizziness, types of dizziness presentations, relevant imaging abnormalities on neuroimaging studies, vestibular testing components, and medical therapy for symptomatic dizziness. This review contains 8 highly rendered figures, 11 tables, and 69 references.

scholarly journals A multiformalism and multiresolution modelling environment: application to the cardiovascular system and its regulation

2009 ◽  
Vol 367 (1908) ◽  
pp. 4923-4940 ◽  
Author(s):  
Alfredo I. Hernández ◽  
Virginie Le Rolle ◽  
Antoine Defontaine ◽  
Guy Carrault
Keyword(s):  
Cardiovascular System ◽  
Modelling And Simulation ◽  
Simulation Environment ◽  
Physiological Conditions ◽  
Systemic Analysis ◽  
Efficient Integration ◽  
Modelling Environment ◽  
Model Components ◽  
Key Aspects

The role of modelling and simulation in the systemic analysis of living systems is now clearly established. Emerging disciplines, such as systems biology, and worldwide research actions, such as the Physiome Project or the Virtual Physiological Human, are based on an intensive use of modelling and simulation methodologies and tools. One of the key aspects in this context is to perform an efficient integration of various models representing different biological or physiological functions, at different resolutions, spanning through different scales. This paper presents a multiformalism modelling and simulation environment (M2SL) that has been conceived to ease model integration. A given model is represented as a set of coupled and atomic model components that may be based on different mathematical formalisms with heterogeneous structural and dynamical properties. A co-simulation approach is used to solve these hybrid systems. The pioneering model of the overall regulation of the cardiovascular system proposed by Guyton and co-workers in 1972 has been implemented under M2SL and a pulsatile ventricular model based on a time-varying elastance has been integrated in a multi-resolution approach. Simulations reproducing physiological conditions and using different coupling methods show the benefits of the proposed environment.

scholarly journals Model Kinetic Equations for Multiply Ionized Gas Mixtures

2021 ◽  
Vol 8 ◽  
Author(s):  
Maria A. Rydalevskaya ◽  
Yulia N. Voroshilova
Keyword(s):  
Equilibrium Distribution ◽  
Local Equilibrium ◽  
Kinetic Equations ◽  
Gas Mixtures ◽  
Distribution Functions ◽  
Transport Processes ◽  
Ionized Gas ◽  
Model Kinetic Equations ◽  
Ideal Gases ◽  
Model Equations

Model kinetic equations are proposed for the description of ionized monoatomic gas mixture flows. The mixtures are assumed enough rarefied to be treated as ideal gases after multiple ionization steps. The model equations contain the equilibrium distribution functions for the components of the gas mixtures under consideration like it was done in BGK equations and their well-known generalizations. However, in this paper the new forms of the equilibrium distribution functions are used which correspond to the entropy maximum under the constraints of momentum, total energy, nuclei and electrons (both bound and free) conservation. It is shown that the derived model equations allow us to study the local equilibrium flows of the ionized gases and the transport processes of energy, nuclei and electrons in the non-equilibrium conditions.

Dizziness

2021 ◽  
Author(s):  
Kevin A. Kerber ◽  
Robert W. Baloh
Keyword(s):  
Vestibular System ◽  
Clinical Medicine ◽  
Background Information ◽  
History Taking ◽  
Symptom Presentation ◽  
Anatomy And Physiology ◽  
Common Causes ◽  
History Of ◽  
Specific Disorders ◽  
Key Aspects

Dizziness is the quintessential symptom presentation in all of clinical medicine. It is a common reason that patients present to a physician. This chapter provides background information about the vestibular system, then reviews key aspects of history-taking and examination of the patient, then discusses specific disorders and common presentation types. Throughout the chapter the focus is on neurologic and vestibular disorders. Normal vestibular anatomy and physiology are discussed, followed by recommendations for history-taking and the physical examination. Specific disorders that cause dizziness are explored, along with common causes of non-specific dizziness. Common presentations are discussed, including acute severe dizziness, recurrent attacks, and recurrent positional vertigo. Finally, the chapter looks at laboratory investigations in diagnosis and management. Figures include population prevalence of dizziness symptoms, the anatomy of inner structures, primary afferent vestibular nerve activity, the head thrust test, the Dix-Hallpike maneuver, the supine positional test, the canalith repositioning procedure, and the barbecue roll maneuver. Tables list physiologic properties and clinical features of the components of the peripheral vestibular system, information to be acquired from history of the present illness, common symptoms patients report as dizziness, examination components, distinguishing among common peripheral and central vertigo syndromes, common causes of nonspecific dizziness, types of dizziness presentations, relevant imaging abnormalities on neuroimaging studies, vestibular testing components, and medical therapy for symptomatic dizziness. This review contains 8 highly rendered figures, 11 tables, and 69 references.

Prediction of Hydrogen Distribution Under Severe Accident Conditions With CFD and Lumped Parameter Codes

2012 ◽  
Author(s):  
Tobias Szabó ◽  
Stefan Benz ◽  
Frank Kretzschmar ◽  
Peter Royl ◽  
Thomas Jordan
Keyword(s):  
Source Term ◽  
Severe Accident ◽  
Test Bed ◽  
Hydrogen Distribution ◽  
Water Steam ◽  
Lumped Parameter ◽  
Accident Conditions ◽  
Energy Balances ◽  
Mass And Energy Balances ◽  
Good Agreement

In case of a severe accident, the containment is the ultimate barrier to the environment. Therefore, reliable simulations tools for containment thermal hydraulics, including hydrogen distribution are indispensable. We simulated the behavior of the containment atmosphere under severe accident conditions with a postulated source term of water, steam and hydrogen. We used a detailed 3D CFD code (GASFLOW) and a lumped parameter code (MELCOR) in order to compare and assess their modeling capabilities. A simplified generic containment including all important components was used as a test bed. We analyzed the calculated pressure histories, mass and energy balances, convective flow as well as steam and hydrogen distributions. Integral values were modeled in good agreement by both codes. The overall flow was reasonably predicted. However we observed discrepancies in the calculated steam and hydrogen concentrations.

scholarly journals Open Issues for Protein Function Assignment in Haloferax volcanii and Other Halophilic Archaea

Genes ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 963
Author(s):  
Friedhelm Pfeiffer ◽  
Mike Dyall-Smith
Keyword(s):  
Protein Function ◽  
Halophilic Archaea ◽  
Haloferax Volcanii ◽  
Background Information ◽  
Strong Focus ◽  
Correct Function ◽  
Key Aspects ◽  
Species Being ◽  
Annotation Errors ◽  
Function Assignment

Background: Annotation ambiguities and annotation errors are a general challenge in genomics. While a reliable protein function assignment can be obtained by experimental characterization, this is expensive and time-consuming, and the number of such Gold Standard Proteins (GSP) with experimental support remains very low compared to proteins annotated by sequence homology, usually through automated pipelines. Even a GSP may give a misleading assignment when used as a reference: the homolog may be close enough to support isofunctionality, but the substrate of the GSP is absent from the species being annotated. In such cases, the enzymes cannot be isofunctional. Here, we examined a variety of such issues in halophilic archaea (class Halobacteria), with a strong focus on the model haloarchaeon Haloferax volcanii. Results: Annotated proteins of Hfx. volcanii were identified for which public databases tend to assign a function that is probably incorrect. In some cases, an alternative, probably correct, function can be predicted or inferred from the available evidence, but this has not been adopted by public databases because experimental validation is lacking. In other cases, a probably invalid specific function is predicted by homology, and while there is evidence that this assigned function is unlikely, the true function remains elusive. We listed 50 of those cases, each with detailed background information, so that a conclusion about the most likely biological function can be drawn. For reasons of brevity and comprehension, only the key aspects are listed in the main text, with detailed information being provided in a corresponding section of the Supplementary Materials. Conclusions: Compiling, describing and summarizing these open annotation issues and functional predictions will benefit the scientific community in the general effort to improve the evaluation of protein function assignments and more thoroughly detail them. By highlighting the gaps and likely annotation errors currently in the databases, we hope this study will provide a framework for experimentalists to systematically confirm (or disprove) our function predictions or to uncover yet more unexpected functions.

scholarly journals Analysis of temperature variations in fixed-bed columns using non-isothermal and non-equilibrium transport model

2020 ◽  
pp. 192-192
Author(s):  
Shireen Zafar ◽  
Sadia Perveen ◽  
Asad Cheema ◽  
Shamsul Qamar
Keyword(s):  
Differential Equations ◽  
Analytical Solutions ◽  
Fixed Bed ◽  
Solution Technique ◽  
Finite Volume Scheme ◽  
Temperature Variations ◽  
Model Equations ◽  
Energy Balances ◽  
Mass And Energy Balances ◽  
Non Equilibrium

A non-isothermal and non-equilibrium two-component lumped kinetic model (LKM) of fixed-bed column liquid chromatography is formulated with the linearized isotherm and solved analytically to study the influence of temperature variations on the process. The model equations constitute a system of convection-diffusion partial differential equations for mass and energy balances in the bulk phase coupled with differential equations for mass and energy balances in the stationary phase. The analytical solutions are derived for Dirichlet boundary conditions by implementing the Laplace transformation, Tschirnhaus-Vieta approach, the linear decomposition technique and an elementary solution technique of ordinary differential equations. An efficient and accurate numerical Laplace inversion technique is applied to bring back the solution in the actual time domain. In order to validate the derived analytical solutions for concentration and temperature fronts, the high-resolution upwind finite volume scheme is applied to approximate the model equations numerically. Various case studies are carried out assuming realistic model parameters. The results obtained will be beneficial for interpreting mass and energy profiles in non-equilibrium and non-isothermal liquid chromatographic columns and provide deeper insight into the sensitivity of the separation process without performing costly and time-consuming laboratory experiments.

scholarly journals Open issues for protein function assignment in Haloferax volcanii and other halophilic archaea

2021 ◽  
Author(s):  
Friedhelm Pfeiffer ◽  
Mike Dyall-Smith
Keyword(s):  
Protein Function ◽  
Halophilic Archaea ◽  
Haloferax Volcanii ◽  
Background Information ◽  
Strong Focus ◽  
Correct Function ◽  
Key Aspects ◽  
Species Being ◽  
Annotation Errors ◽  
Function Assignment

Background: Annotation ambiguities and annotation errors are a general challenge in genomics. While a reliable protein function assignment can be obtained by experimental characterization, this is expensive and time-consuming, and the number of such Gold Standard Proteins (GSP) with experimental support remains very low compared to proteins annotated by sequence homology, usually through automated pipelines. Even a GSP may give a misleading assignment when used as a reference: the homolog may be close enough to support isofunctionality, but the substrate of the GSP is absent from the species being annotated. In such cases the enzymes cannot be isofunctional. Here, we examine a variety of such issues in halophilic archaea (class Halobacteria), with a strong focus on the model haloarchaeon Haloferax volcanii. Results: Annotated proteins of Hfx. volcanii were identified for which public databases tend to assign a function that is probably incorrect. In some cases, an alternative, probably correct, function can be predicted or inferred from the available evidence but this has not been adopted by public databases because experimental validation is lacking. In other cases, a probably invalid specific function is predicted by homology, and while there is evidence that this assigned function is unlikely, the true function remains elusive. We list 50 of those cases, each with detailed background information so that a conclusion about the most likely biological function can be drawn. For reasons of brevity and comprehension, only key aspects are listed in the main text, with detailed information being provided in a corresponding section of the Supplementary Material. Conclusions: Compiling, describing and summarizing these open annotation issues and functional predictions will benefit the scientific community in the general effort to improve the evaluation of protein function assignments and more thoroughly detail them. By highlighting the gaps and likely annotation errors currently in the databases, we hope this study will provide a framework for experimentalists to sytematically confirm (or disprove) our function predictions or to uncover yet unexpected functions.

Helecom Communications: Considering Fraud Risk on an Engagement before and after Analyzing a Key Business Process

2005 ◽  
Vol 20 (1) ◽  
pp. 99-118 ◽  
Author(s):  
Brian Ballou ◽  
Jennifer M. Mueller
Keyword(s):  
Business Process ◽  
Process Analysis ◽  
Background Information ◽  
International Accounting ◽  
Fraud Risk ◽  
Business Process Analysis ◽  
Public Company ◽  
Before And After ◽  
Key Aspects

Helecom Communications is a fictitious public company in the cable industry, founded by its current Chairman and CEO, Jefferson Means. For this case, students assume the role of an entry-level accountant in an international accounting firm that has just acquired this client. Students are provided with background information on the company and its environment in Part I of the case and provided with information related to a critical business process, subscriber management, in Part II of the case. This case involves audit planning, considering fraud risk of an organization in a competitive, regulated, and volatile industry. For this case, the established criterion is AICPA Statement of Auditing Standards No. 99, Consideration of Fraud in a Financial Statement Audit (SAS No. 99). While many of the facts in the case are adapted from fraud risks and actions that occurred at actual organizations, the company is fictitious to enable the case to place students in the role of the auditor evaluating the organization for fraud risks both before and after analyzing a key business process. By performing the requirements in this case, students are exposed the key aspects of SAS No. 99, which should be maintained and possibly expanded pursuant to consideration by the Public Company Accounting Oversight Board (PCAOB), within the context of audit approaches being used to some extent by all international accounting firms (e.g., Lemon et al. 2000). The case illustrates the usefulness of business process analysis for assessing fraud risk as well as the iterative nature of the assessment.

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