Educational Model for the Kinematic Study of Non-Circular Gears

2013 ◽  
Vol 332 ◽  
pp. 297-304
Author(s):  
Liviu Ciupitu
Keyword(s):  
Numerical Methods ◽  
Industrial Applications ◽  
Point Of View ◽  
Spur Gears ◽  
Test Rig ◽  
Educational Model ◽  
Educational Test ◽  
Kinematic Study ◽  
Variation Curve ◽  
Noncircular Gears

The noncircular gears are used more and more in industrial applications. The paper presents an educational test rig for the kinematic study of non-circular gears. Two gears are studied from kinematic theoretically point of view: a gear with identically oval spur gears and another gear with identically elliptical spur gears, and simulation diagrams are presented. As for the testing rig, a gear with identically oval spur gears has been used. The researchers are able to draw with high precision the variation curve of output angle with respect to input angle. By using numerical methods for integration and differentiation other diagrams could be drawn and a comparation with simulation diagrams could be made.

Enzyme Promiscuous Activity: How to Define it and its Evolutionary Aspects

2020 ◽  
Vol 27 (5) ◽  
pp. 400-410
Author(s):  
Valentina De Luca ◽  
Luigi Mandrich
Keyword(s):  
Gene Evolution ◽  
Sequence Divergence ◽  
High Specificity ◽  
Industrial Applications ◽  
Point Of View ◽  
Enzyme Promiscuity ◽  
Primary Activity ◽  
Starting Point ◽  
Main Activity

: Enzymes are among the most studied biological molecules because better understanding enzymes structure and activity will shed more light on their biological processes and regulation; from a biotechnological point of view there are many examples of enzymes used with the aim to obtain new products and/or to make industrial processes less invasive towards the environment. Enzymes are known for their high specificity in the recognition of a substrate but considering the particular features of an increasing number of enzymes this is not completely true, in fact, many enzymes are active on different substrates: this ability is called enzyme promiscuity. Usually, promiscuous activities have significantly lower kinetic parameters than to that of primary activity, but they have a crucial role in gene evolution. It is accepted that gene duplication followed by sequence divergence is considered a key evolutionary mechanism to generate new enzyme functions. In this way, promiscuous activities are the starting point to increase a secondary activity in the main activity and then get a new enzyme. The primary activity can be lost or reduced to a promiscuous activity. In this review we describe the differences between substrate and enzyme promiscuity, and its rule in gene evolution. From a practical point of view the knowledge of promiscuity can facilitate the in vitro progress of proteins engineering, both for biomedical and industrial applications. In particular, we report cases regarding esterases, phosphotriesterases and cytochrome P450.

scholarly journals Suboptimal Disturbance Observer Design Using All Stabilizing Q Filter for Precise Tracking Control

Mathematics ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1434 ◽  
Author(s):  
Wonhee Kim ◽  
Sangmin Suh
Keyword(s):  
Design Method ◽  
Industrial Applications ◽  
Point Of View ◽  
Observer Design ◽  
Linear Matrix ◽  
External Disturbances ◽  
Closed Loop Systems ◽  
Control Target ◽  
The Stability ◽  
Unified Index

For several decades, disturbance observers (DOs) have been widely utilized to enhance tracking performance by reducing external disturbances in different industrial applications. However, although a DO is a verified control structure, a conventional DO does not guarantee stability. This paper proposes a stability-guaranteed design method, while maintaining the DO structure. The proposed design method uses a linear matrix inequality (LMI)-based H∞ control because the LMI-based control guarantees the stability of closed loop systems. However, applying the DO design to the LMI framework is not trivial because there are two control targets, whereas the standard LMI stabilizes a single control target. In this study, the problem is first resolved by building a single fictitious model because the two models are serial and can be considered as a single model from the Q-filter point of view. Using the proposed design framework, all-stabilizing Q filters are calculated. In addition, for the stability and robustness of the DO, two metrics are proposed to quantify the stability and robustness and combined into a single unified index to satisfy both metrics. Based on an application example, it is verified that the proposed method is effective, with a performance improvement of 10.8%.

Characterisation of supersonic gas jets for different nozzle geometries for laser-plasma acceleration experiments at SPARC_LAB

2022 ◽  
Vol 17 (01) ◽  
pp. C01049
Author(s):  
G. Costa ◽  
M.P. Anania ◽  
A. Biagioni ◽  
F.G. Bisesto ◽  
M. Del Franco ◽  
...  
Keyword(s):  
High Power ◽  
Plasma Channel ◽  
Laser Pulses ◽  
Industrial Applications ◽  
Point Of View ◽  
Theoretical Point ◽  
High Power Laser ◽  
Power Laser ◽  
Neutral Gas ◽  
Nozzle Geometries

Abstract Plasma-based technology promises a tremendous reduction in size of accelerators used for research, medical, and industrial applications, making it possible to develop tabletop machines accessible for a broader scientific community. The use of high-power laser pulses on gaseous targets is a promising method for the generation of accelerated electron beams at energies on the GeV scale, in extremely small sizes, typically millimetres. The gaseous target in question can be a collimated supersonic gasjet from a nozzle. In this work, a technique for optimising the so generated plasma channel is presented. In detail, a study on the influence of the nozzle throat shape in relation to the uniformity and density of the generated plasma profile is reported. These considerations are discussed first of all from a theoretical point of view, by means of a stationary one-dimensional mathematical model of the neutral gas, thus exploiting the possibility of comparing the properties of the output flow for different nozzle geometries. This is combined with an experimental approach using interferometric longitudinal density measurements of the plasma channel. The latter is generated by a high-power laser pulse focused on a helium gasjet, in the SPARC_LAB laboratories.

scholarly journals Bioaccessibility of Marine Carotenoids

Marine Drugs ◽  
2018 ◽  
Vol 16 (10) ◽  
pp. 397 ◽  
Author(s):  
Isabel Viera ◽  
Antonio Pérez-Gálvez ◽  
María Roca
Keyword(s):  
Pharmaceutical Industry ◽  
Human Health ◽  
Industrial Production ◽  
Food Industry ◽  
Industrial Applications ◽  
Point Of View ◽  
Market Area ◽  
Biological Functions ◽  
Determination Methods ◽  
Nutraceutical Properties

The benefit of carotenoids to human health is undeniable and consequently, their use for this purpose is growing rapidly. Additionally, the nutraceutical properties of carotenoids have attracted attention of the food industry, especially in a new market area, the ‘cosmeceuticals.’ Marine organisms (microalgae, seaweeds, animals, etc.) are a rich source of carotenoids, with optimal properties for industrial production and biotechnological manipulation. Consequently, several papers have reviewed the analysis, characterization, extraction and determination methods, biological functions and industrial applications. But, now, the bioaccessibility and bioactivity of marine carotenoids has not been focused of any review, although important achievements have been published. The specific and diverse characteristic of the marine matrix determines the bioavailability of carotenoids, some of them unique in the nature. Considering the importance of the bioavailability not just from the health and nutritional point of view but also to the food and pharmaceutical industry, we consider that the present review responds to an actual demand.

scholarly journals NUMERICAL MODELING OF GAS TURBINE COOLED BLADES

Aviation ◽  
2005 ◽  
Vol 9 (3) ◽  
pp. 9-18
Author(s):  
Arif Pashayev ◽  
Djakhangir Askerov ◽  
Ramiz Ali Cabar oqlu Sadiqov
Keyword(s):  
Numerical Modeling ◽  
Temperature Field ◽  
Numerical Methods ◽  
Mathematical Models ◽  
Gas Turbine ◽  
Point Of View ◽  
Theoretical Substantiation ◽  
Stationary Temperature Field ◽  
Methods Of Calculation ◽  
Effective Combination

In contrast to methods that do not take into account multiconnectivity in a broad sense of this term, we develop mathematical models and highly effective combination (BIEM and FDM) numerical methods of calculation of stationary and quasi‐stationary temperature field of a profile part of a blade with convective cooling (from the point of view of realization on PC). The theoretical substantiation of these methods is proved by appropriate theorems. For it, converging quadrature processes have been developed and the estimations of errors in the terms of A. Ziqmound continuity modules have been received.

scholarly journals From Hertzian contact to spur gears: analyses of stresses and rolling contact fatigue

2019 ◽  
Vol 20 (6) ◽  
pp. 626 ◽  
Author(s):  
Guillaume Vouaillat ◽  
Jean-Philippe Noyel ◽  
Fabrice Ville ◽  
Xavier Kleber ◽  
Sylvain Rathery
Keyword(s):  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Spur Gear ◽  
Point Of View ◽  
Rolling Contact ◽  
Hertzian Contact ◽  
Spur Gears ◽  
Realistic Representation ◽  
Contact Fatigue Life ◽  
Surface Microgeometry

The study of rolling contact fatigue in spur gears requires a good comprehension of all the phenomena occurring at the material scale. On a numerical point of view, a realistic representation of the material and of the load repartition function of the local micro-geometries is needed. However the resulting models are often complex and time-consuming. So, this work aims at developing a model meeting these specificities. Thus, different sections of the spur gear material granular geometry are simulated first. Secondly, the contact pressure fields are computed accurately relatively to the simulated surface microgeometry. Then, the influence of several parameters on their rolling contact fatigue life is highlighted. Among friction, sliding coefficient, load variation and roughness, these individual or combined parameters are taken into account in the model, tested and their impact stressed out. Finally, a fatigue criteria based on rolling contact fatigue micro-cracks nucleation at grain boundaries is proposed in order to compare simulations and influencing parameters to the reference.

Influence of manufacturing error tolerances on contact pressure in gears

2020 ◽  
pp. 095440622097671
Author(s):  
Rikard Hjelm ◽  
Hans Hansson ◽  
Aylin Ahadi ◽  
Carin Andersson ◽  
Jens Wahlström
Keyword(s):  
Contact Pressure ◽  
Industrial Applications ◽  
Spur Gears ◽  
Pitch Error ◽  
Simulation Based ◽  
Manufacturing Errors ◽  
Gear Manufacturing ◽  
Parametric Description ◽  
Gear Geometry ◽  
Slope Error

Gear manufacturing always results in some degree of manufacturing errors, i.e. deviations from the desired gear geometry. These errors alter how the gears mesh, typically causing increased contact pressure which in turn shortens service life. It is therefore crucial to choose tolerances such that excessive contact pressure, and especially tip contact, is avoided. With increasing demands due to electrification, this becomes even more important. The aim of this paper is to study how pitch error and profile slope error affect the contact pressure in spur gears sets. The meshing is simulated using a novel simulation approach that uses a parametric description of the reference profile and gear geometry, and a hybrid model for the compliance. The method includes tooth modifications such as tip relief, and uses the true geometry to find contacts. Thus, it also handles contact outside the nominal line of action, including tip contact. The study includes cases where a gear is subjected to both pitch error and profile slope error simultaneously. Numerical examples, relevant to the automotive industry, show the outcome of the simulations. It is shown how simulation-based tolerances for relevant industrial applications can be used to improve manufacturing outcome.

Combustion Dynamics in a Gas Turbine Single Annular Combustor Sector

2010 ◽  
Author(s):  
Fumitaka Ichihashi ◽  
Jun Cai ◽  
Y. H. Kao ◽  
A. A. Syed ◽  
S. M. Jeng
Keyword(s):  
Gas Turbine ◽  
Acoustic Impedance ◽  
Acoustic Analysis ◽  
Industrial Applications ◽  
Propagation Model ◽  
Future Research ◽  
Test Rig ◽  
Combustion Dynamics ◽  
Resonance Modes ◽  
Impedance Characteristics

The occurrence of combustion instability dynamics known, as “screech, howl and growl,” in the combustors of gas turbine engines is a very difficult challenge for engineers. The very high amplitude pressure oscillations caused by combustion dynamics, are not only detrimental to the operation of the engine and combustor, but the difficulty in predicting and remedying these problems can lead to significant costs and delays in engine development. The coupling of the unsteady heat release in the flame with the natural acoustic resonance modes of the combustor duct causes the phenomena of combustion dynamics. To improve our understanding of stability characteristics in such complex systems, encountered in many industrial applications, the flame structure of an atmospheric swirl-stabilized burner, containing dilution and cooling air holes and fed with natural gas fuel, was systematically investigated for various inlet temperatures, pressure drops and air-fuel ratios. Experiments were also designed and conducted with the goal to understand better the phenomena of combustion dynamics that were experienced. More specifically, six acoustic pressure transducers were incorporated in the combustor and in the upstream duct to measure the acoustic field and the acoustic impedance characteristics at specified locations of interest. A one-dimensional wave propagation model is presented to predict the acoustic frequencies and damping of resonance modes, based on the geometry of the test rig, the flow conditions, and the acoustic impedance characteristics of the terminations of the combustor. This paper will present the acoustic analysis of the test data in the light of the above-mentioned theoretical modeling. The limitations of the current test rig are pointed out and changes in the rig design are discussed for future research.

scholarly journals Optical Characterization of Homogeneous and Heterogeneous Intralipid-Based Samples

2020 ◽  
Vol 10 (18) ◽  
pp. 6234
Author(s):  
Ines Delfino ◽  
Maria Lepore ◽  
Rosario Esposito
Keyword(s):  
Optical Properties ◽  
Light Scattering ◽  
Scattered Light ◽  
Industrial Applications ◽  
Point Of View ◽  
Turbid Media ◽  
Time Resolved ◽  
Propagation Of Light ◽  
First Time

Different scattering processes take place when photons propagate inside turbid media. Many powerful experimental techniques exploiting these processes have been developed and applied over the years in a large variety of situations from fundamental and applied research to industrial applications. In the present paper, we intend to take advantage of Static Light Scattering (SLS), Dynamic Light Scattering (DLS), and Time-Resolved Transmittance (TRT) for investigating all the different scattering regimes by using scattering suspensions in a very large range of scatterer concentrations. The suspensions were prepared using Intralipid 20%, a material largely employed in studies of the optical properties of turbid media, with concentrations from 10−5% to 50%. By the analysis of the angular and temporal dependence of the scattered light, a more reliable description of the scattering process occurring in these samples can be obtained. TRT measurements allowed us to obtain information on the reduced scattering coefficient, an important parameter largely used in the description of the optical properties of turbid media. TRT was also employed for the detection of inclusions embedded in Intralipid suspensions, by using a properly designed data analysis. The present study allowed us to better elucidate the dependence of scattering properties of Intralipid suspensions in a very large concentration range and the occurrence of the different scattering processes involved in the propagation of light in turbid media for the first time to our knowledge. In so doing, the complementary contribution of SLS, DLS, and TRT in the characterization of turbid media from an optical and structural point of view is strongly evidenced.

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