On the Application of Roller Rigs for Studying Rail Vehicle Systems

2013 ◽  
Author(s):  
Sajjad Z. Meymand ◽  
Michael J. Craft ◽  
Mehdi Ahmadian
Keyword(s):  
Field Testing ◽  
Operating Conditions ◽  
Railway Vehicle ◽  
Railroad Industry ◽  
Railway Systems ◽  
Advantages And Disadvantages ◽  
Field Environment ◽  
Adhesion Wear ◽  
Wide Range ◽  
Vehicle Systems

The primary intent of this study is to highlight the advantages and disadvantages of using roller rigs for engineering issues of importance to the railroad industry. Roller rigs have been in existence for more than a century for studying railway vehicle behavior. In contrast to field testing, roller rigs offer a controlled laboratory environment that can provide a successful path for obtaining data on the mechanics and dynamics of railway systems for a variety of operating conditions. Their use, however, imposes discrepancies from the field environment due to the nature of the commonly-used roller design. This study describes different rig configurations, including scaled and full-scale rigs. It includes the potential advantages and limitations of various rigs for conducting a wide range of studies concerning the dynamic stability of railcars, wheel–rail adhesion, wear and fatigue mechanisms, braking systems, and locomotive power.

scholarly journals Assessing the Sensitivity of Stall-Regulated Wind Turbine Power to Blade Design Using High-Fidelity Computational Fluid Dynamics

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Andrea G. Sanvito ◽  
Giacomo Persico ◽  
M. Sergio Campobasso
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Field Testing ◽  
Turbine Rotor ◽  
Operating Conditions ◽  
High Fidelity ◽  
Blade Design ◽  
Computationally Efficient ◽  
Wind Speeds ◽  
Wide Range

Abstract This study provides a novel contribution toward the establishment of a new high-fidelity simulation-based design methodology for stall-regulated horizontal axis wind turbines. The aerodynamic design of these machines is complex, due to the difficulty of reliably predicting stall onset and poststall characteristics. Low-fidelity design methods, widely used in industry, are computationally efficient, but are often affected by significant uncertainty. Conversely, Navier–Stokes computational fluid dynamics (CFD) can reduce such uncertainty, resulting in lower development costs by reducing the need of field testing of designs not fit for purpose. Here, the compressible CFD research code COSA is used to assess the performance of two alternative designs of a 13-m stall-regulated rotor over a wide range of operating conditions. Validation of the numerical methodology is based on thorough comparisons of novel simulations and measured data of the National Renewable Energy Laboratory (NREL) phase VI turbine rotor, and one of the two industrial rotor designs. An excellent agreement is found in all cases. All simulations of the two industrial rotors are time-dependent, to capture the unsteadiness associated with stall which occurs at most wind speeds. The two designs are cross-compared, with emphasis on the different stall patterns resulting from particular design choices. The key novelty of this work is the CFD-based assessment of the correlation among turbine power, blade aerodynamics, and blade design variables (airfoil geometry, blade planform, and twist) over most operational wind speeds.

scholarly journals Alkaline-Based Catalysts for Glycerol Polymerization Reaction: A Review

2020 ◽  
Author(s):  
Negisa Ebadipour ◽  
Sébastien Paul ◽  
Benjamin Katryniok ◽  
Franck Dumeignil
Keyword(s):  
Heterogeneous Catalysts ◽  
Antimicrobial Agents ◽  
Reaction Medium ◽  
Operating Conditions ◽  
Polymerization Reaction ◽  
High Catalytic Activity ◽  
Catalytic Systems ◽  
Glycerol Conversion ◽  
Advantages And Disadvantages ◽  
Wide Range

Polyglycerols (PGs) are biocompatible and highly functional polyols with a wide range of applications, such as emulsifiers, stabilizers, antimicrobial agents, in many industries including cosmetics, food, plastic and biomedical. The demand increase for biobased PGs encourages researchers to develop new catalytic systems for glycerol polymerization. This review focuses on alkaline homogeneous and heterogeneous catalysts. The performances of the alkaline catalysts are compared in terms of conversion and selectivity, and their respective advantages and disadvantages are commented. While homogeneous catalysts exhibit a high catalytic activity, they cannot be recycled and reused, whereas solid catalysts can be partially recycled. The key issue for heterogenous catalytic systems, which is unsolved so far, is linked to their instability due to partial dissolution in the reaction medium. Further, this paper also reviews the proposed mechanisms of glycerol polymerization over alkaline-based catalysts and discuss the various operating conditions with an impact on the performances. More particularly, temperature and amount of catalyst proved to have a significant influence on glycerol conversion and on its polymerization extent.

scholarly journals Alkaline-Based Catalysts for Glycerol Polymerization Reaction: A Review

Catalysts ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1021
Author(s):  
Negisa Ebadipour ◽  
Sébastien Paul ◽  
Benjamin Katryniok ◽  
Franck Dumeignil
Keyword(s):  
Heterogeneous Catalysts ◽  
Antimicrobial Agents ◽  
Reaction Medium ◽  
Operating Conditions ◽  
Polymerization Reaction ◽  
High Catalytic Activity ◽  
Catalytic Systems ◽  
Glycerol Conversion ◽  
Advantages And Disadvantages ◽  
Wide Range

Polyglycerols (PGs) are biocompatible and highly functional polyols with a wide range of applications, such as emulsifiers, stabilizers and antimicrobial agents, in many industries including cosmetics, food, plastic and biomedical. The demand increase for biobased PGs encourages researchers to develop new catalytic systems for glycerol polymerization. This review focuses on alkaline homogeneous and heterogeneous catalysts. The performances of the alkaline catalysts are compared in terms of conversion and selectivity, and their respective advantages and disadvantages are commented. While homogeneous catalysts exhibit a high catalytic activity, they cannot be recycled and reused, whereas solid catalysts can be partially recycled. The key issue for heterogenous catalytic systems, which is unsolved thus far, is linked to their instability due to partial dissolution in the reaction medium. Further, this paper also reviews the proposed mechanisms of glycerol polymerization over alkaline-based catalysts and discusses the various operating conditions with an impact on performance. More particularly, temperature and amount of catalyst are proven to have a significant influence on glycerol conversion and on its polymerization extent.

Producing and Measuring the 3rd Body Layer

2020 ◽  
Author(s):  
Harold Harrison
Keyword(s):  
Field Testing ◽  
Operating Conditions ◽  
Ambient Conditions ◽  
Railroad Industry ◽  
Current State ◽  
Starting Point ◽  
Virgin State ◽  
Standard Practices ◽  
Wear Products ◽  
And Control

Abstract Decades of measuring friction conditions at the wheel-rail interface have resulted in widely varying answers produced by different measurement methods and devices. This variation is a result of many factors, some of which are difficult to quantify and control, especially under field conditions. One of these variables is the presence of an unknown 3rd body layer material, whose accumulation on the wheel and rail surfaces affect the value of independent tests performed to quantify the nominal state of wheel on rail in actual operating conditions. This paper describes a series of tests undertaken to understand the creation of the 3rd body layer from the starting point of clean wheel and rail surfaces and how that can lead to new standard practices for field testing. A 2 × 2 matrix of wheel and rail conditions is defined to help formalize the discussion of the production and measurement of the 3rd body layer. Case 1 is the nominal virgin state of the two materials. This is actually fairly hard to produce. Almost any process and/or handling will leave some films on both surfaces. Lab tests typically start in this state after cleaning/degreasing the surfaces following machining or sanding. Cases 2 and 3 are potentially the same (clean wheel or rail), however, the more likely case is Case 2 where some existing location on actual track is chosen to determine its current state, thus the use of a Tribometer using a clean wheel. Case 4 represents the nominal state of most track with passing vehicles where the current environmental/ambient conditions encourage a particular set of 3rd body wear products. This formalization helps reveal the prior common practices that have produced assumptions of what is the ‘correct’ value and how that has created a bias in one’s thinking of what really exists in normal revenue service. This issue is particularly consequential in attempting to quantify the benefit of the friction modifiers that are being adopted across the railroad industry.

Assessing the Sensitivity of Stall-Regulated Wind Turbine Power to Blade Design Using High-Fidelity CFD

2019 ◽  
Author(s):  
A. G. Sanvito ◽  
G. Persico ◽  
M. S. Campobasso
Keyword(s):  
Field Testing ◽  
Turbine Rotor ◽  
Operating Conditions ◽  
High Fidelity ◽  
Blade Design ◽  
Computationally Efficient ◽  
Wind Speeds ◽  
Design Variables ◽  
Wide Range ◽  
Horizontal Axis Wind Turbines

Abstract This study provides a novel contribution towards the establishment of a new high–fidelity simulation–based design methodology for stall–regulated horizontal axis wind turbines. The aerodynamic design of these machines is complex, due to the difficulty of reliably predicting stall onset and post–stall characteristics. Low–fidelity design methods, widely used in industry, are computationally efficient, but are often affected by significant uncertainty. Conversely, Navier–Stokes CFD can reduce such uncertainty, resulting in lower development costs by reducing the need of field testing of designs not fit for purpose. Here, the compressible CFD research code COSA is used to assess the performance of two alternative designs of a 13–meter stall–regulated rotor over a wide range of operating conditions. Validation of the numerical methodology is based on thorough comparisons of novel simulations and measured data of the NREL Phase VI turbine rotor, and one of the two industrial rotor designs. An excellent agreement is found in all cases. All simulations of the two industrial rotors are time–dependent, to capture the unsteadiness associated with stall which occurs at most wind speeds. The two designs are cross-compared, with emphasis on the different stall patterns resulting from particular design choices. The key novelty of this work is the CFD–based assessment of the correlation among turbine power, blade aerodynamics, and blade design variables (airfoil geometry, blade planform and twist) over most operational wind speeds.

scholarly journals Multi-Dimensional Modeling of the CFR Engine for the Investigation of SI Natural Gas Combustion and Controlled End-Gas Autoignition

2020 ◽  
Author(s):  
Diego Bestel ◽  
Scott Bayliff ◽  
Anthony Marchese ◽  
Daniel Olsen ◽  
Bret Windom ◽  
...  
Keyword(s):  
Natural Gas ◽  
Chemical Reactivity ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Cfd Modeling ◽  
General Tendency ◽  
Natural Gas Engines ◽  
Advantages And Disadvantages ◽  
Crank Angle ◽  
Wide Range

Abstract Engine knock and misfire are barriers to pathways leading to high-efficiency Spark-Ignited (SI) Natural Gas engines. The general tendency to knock is highly dependent on engine operating conditions and the fuel reactivity. The problem is further complicated by low emission limits and the wide range of chemical reactivity in pipeline quality natural gas. Depending on the region and the source of the natural gas, its reactivity, described by its methane number (analogous to the octane number for liquid SI fuels) can span from 65–95. In order to realize diesel-like efficiencies, SI natural gas engines must be designed to operate at high BMEP near knock limits over a wide range of fuel reactivity. This requires a deep understanding regarding the combustion-engine interactions pertaining to flame propagation and end-gas autoignition (EGAI). However, EGAI, if controlled, provides an opportunity to increase SI natural gas engine efficiency by increasing combustion rate and the total burned fuel, mitigating the effects of the slow flame speeds of natural gas fuels which generally reduce BMEP and increase unburned hydrocarbon emissions. For this reason, in order to study EGAI phenomenon, the present work highlights multi-dimensional computational fluid dynamics (CFD) models of the Cooperative Fuel Research (CFR) engine. The CFR engine models are used to investigate fuel-engine interactions that lead to EGAI with natural gas, including effects of fuel reactivity, engine operating parameters, and exhaust gas recirculation (EGR). A Three-Pressure Analysis, performed with GT-Power, was used to estimate initial and boundary conditions for the three-dimensional CFD model. CONVERGE CFD v2.4 was used for the three-dimensional CFD modeling where the level set G-Equation model and SAGE detailed chemical kinetics solver were used. An assessment of the different modeling approaches is also provided to evaluate their limitations, advantages and disadvantages, and for which situations they are most applicable. Model validation was performed with experimental data taken with a CFR engine over varying compression ratio, CA50, EGR fraction, and IMEP and shows good agreement in Peak Cylinder Pressure (PCP), PCP crank angle, and the location of the 10%, 50%, and 90% mass fraction burned (CA10, CA50, and CA90, respectively). The models can predict the onset crank angle and pressure rise rate for light, medium, and heavy EGAI under a variety of fuel reactivities and engine operating conditions.

Comparison of Deterministic and Linear Cosine Spatial Filtering of Transmission Electron Micrographs

1972 ◽  
Vol 30 ◽  
pp. 596-597
Author(s):  
David A. Ansley
Keyword(s):  
Spherical Aberration ◽  
Focal Length ◽  
Chromatic Aberration ◽  
Spatial Filter ◽  
Operating Conditions ◽  
Objective Lens ◽  
List Type ◽  
Spatial Filters ◽  
Transmission Electron ◽  
Wide Range

The coherence of the electron flux of a transmission electron microscope (TEM) limits the direct application of deconvolution techniques which have been used successfully on unmanned spacecraft programs. The theory assumes noncoherent illumination. Deconvolution of a TEM micrograph will, therefore, in general produce spurious detail rather than improved resolution.A primary goal of our research is to study the performance of several types of linear spatial filters as a function of specimen contrast, phase, and coherence. We have, therefore, developed a one-dimensional analysis and plotting program to simulate a wide 'range of operating conditions of the TEM, including adjustment of the:(1) Specimen amplitude, phase, and separation(2) Illumination wavelength, half-angle, and tilt(3) Objective lens focal length and aperture width(4) Spherical aberration, defocus, and chromatic aberration focus shift(5) Detector gamma, additive, and multiplicative noise constants(6) Type of spatial filter: linear cosine, linear sine, or deterministic

MODERN EQUIPMENT FOR DETERMINING TRACTOR-SPEED PROPERTIES OF THE VEHICLE: CHARACTERISTICS’ ANALYSIS IN LABORATORY CONDITIONS

2019 ◽  
Vol 16 (3) ◽  
pp. 276-289
Author(s):  
N. V. Savenkov ◽  
V. V. Ponyakin ◽  
S. A. Chekulaev ◽  
V. V. Butenko
Keyword(s):  
Environmental Performance ◽  
Operating Conditions ◽  
Special Role ◽  
Development Stages ◽  
Advantages And Disadvantages ◽  
Force Transfer ◽  
Characteristics Analysis ◽  
And Performance ◽  
Loading Devices ◽  
Structural Solutions

Introduction. At present, stands with running drums are widely used for various types of tests. Power stands play a special role. Such stands take the mechanical power from the driving wheels of the car. This simulates the process of movement of the vehicle under operating conditions. Such equipment has various designs, principles of operation and performance. It is also used in tests that are different by purpose, development stages and types: research, control, certification, etc. Therefore, it is necessary in order to determine the traction-speed, fuel-efficient and environmental performance characteristics.Materials and methods. The paper provides the overview of the power stands with running drums, which are widespread on the domestic market. The authors carried out the analysis of the main structural solutions: schemes of force transfer between the wheel and the drum; types of loading devices; transmission layout schemes and features of the control and measuring complex. The authors also considered corresponding advantages and disadvantages, recommended spheres of application, demonstrated parameters and characteristics of the units’ workflow, presented components and equipment.Discussion and conclusions. The authors critically evaluate existing models of stands with running drums. Such information is useful for choosing serial models of stands and for developing technical tasks for designing or upgrading the equipment.

Structure and properties of compact articles from high-alloyed iron powder with adding of boron nitride

2020 ◽  
pp. 39-48
Author(s):  
B. O. Bolshakov ◽  
◽  
R. F. Galiakbarov ◽  
A. M. Smyslov ◽  
◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Boron Nitride ◽  
Grain Boundary ◽  
Bending Strength ◽  
Physical And Mechanical Properties ◽  
Operating Conditions ◽  
Structure And Properties ◽  
Steam Turbines ◽  
Friction Forces ◽  
Wide Range

The results of the research of structure and properties of a composite compact from 13 Cr – 2 Мо and BN powders depending on the concentration of boron nitride are provided. It is shown that adding boron nitride in an amount of more than 2% by weight of the charge mixture leads to the formation of extended grain boundary porosity and finely dispersed BN layers in the structure, which provides a high level of wearing properties of the material. The effect of boron nitride concentration on physical and mechanical properties is determined. It was found that the introduction of a small amount of BN (up to 2 % by weight) into the compacts leads to an increase in plasticity, bending strength, and toughness by reducing the friction forces between the metal powder particles during pressing and a more complete grain boundary diffusion process during sintering. The formation of a regulated structure-phase composition of powder compacts of 13 Cr – 2 Mо – BN when the content of boron nitride changes in them allows us to provide the specified physical and mechanical properties in a wide range. The obtained results of studies of the physical and mechanical characteristics of the developed material allow us to reasonably choose the necessary composition of the powder compact for sealing structures of the flow part of steam turbines, depending on their operating conditions.

The Management of Post-Tonsillectomy Morbidity in Patients With Sleep Apnoea

2019 ◽  
Vol 70 (10) ◽  
pp. 3738-3740
Keyword(s):  
Day Surgery ◽  
Sleep Apnoea ◽  
Integrative Approach ◽  
Multicenter Studies ◽  
Therapeutic Modalities ◽  
Advantages And Disadvantages ◽  
Obstructive Sleep ◽  
Wide Range ◽  
The Impact ◽  
Surgery Center

The Tonsillectomy in children or adults is an intervention commonly encountered in the ENT (Ear Nose and Throat) and Head and Neck surgeon practice. The current tendency is to perform this type of surgery in major ambulatory surgery centers. Two objectives are thus pursued: first of all, the increase of the patient quality of life through the reintegration into the family as quickly as possible and secondly, the expenses associated with continuous hospitalization are reduced. Any tertiary (multidisciplinary) sleep center must ensure the complete diagnosis and treatment (including surgery) of sleep respiratory disorders. Under these conditions the selection of patients and especially the implementation of the specific protocols in order to control the postoperative complications it becomes essential. The present paper describes our experience of tonsillectomy as treatment for selected patients with chronic rhonchopathy (snoring) and mild to moderate obstructive sleep apnoea. It was presented the impact of antibiotics protocols in reducing the main morbid outcomes following tonsillectomy, in our day surgery center. The obtained results can also be a prerequisite for the integrative approach of the patients with sleep apnoea who were recommended surgical treatment. Considering the wide range of therapeutic modalities used in sleep apnoea, each with its specific advantages and disadvantages, more extensive and multicenter studies are needed. Keywords: post-tonsillectomy morbidity, day surgery center, sleep disorders

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