Study of the role of the catalyst and operating conditions on the sediments formation during deep hydroconversion of vacuum residue

2012 ◽  
Vol 411-412 ◽  
pp. 35-43 ◽  
Author(s):  
Charles Marchal ◽  
Denis Uzio ◽  
Isabelle Merdrignac ◽  
Loïc Barré ◽  
Christophe Geantet
Keyword(s):  
Operating Conditions ◽  
Vacuum Residue

Role of Reynolds and Archimedes numbers in particle-fluid flows

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Haim Kalman
Keyword(s):  
Flow Regime ◽  
Power Function ◽  
Fluid Flows ◽  
Limited Range ◽  
Operating Conditions ◽  
Pneumatic Conveying ◽  
Particulate Materials ◽  
Simple Power ◽  
Simple Power Function

AbstractAny scientific behavior is best represented by nondimensional numbers. However, in many cases, for pneumatic conveying systems, dimensional equations are developed and used. In some cases, many of the nondimensional equations include Reynolds (Re) and Froude (Fr) numbers; they are usually defined for a limited range of materials and operating conditions. This study demonstrates that most of the relevant flow types, whether in horizontal or vertical pipes, can be better described by Re and Archimedes (Ar) numbers. Ar can also be used in hydraulic conveying systems. This paper presents many threshold velocities that are accurately defined by Re as a simple power function of Ar. Many particulate materials are considered by Ar, thereby linking them to a common behavior. Using various threshold velocities, a flow regime chart for horizontal conveying is presented in this paper.

The Role of Offshore Monitoring in an Effective Deepwater Riser Integrity Management Program

2007 ◽  
Author(s):  
Brittany Goldsmith ◽  
Elizabeth Foyt ◽  
Madhu Hariharan
Keyword(s):  
Failure Modes ◽  
Human Life ◽  
Management Program ◽  
Measured Data ◽  
Operating Conditions ◽  
Environmental Damage ◽  
Positioning Systems ◽  
Integrity Management ◽  
Deepwater Riser

As offshore field developments move into deeper water, one of the greatest challenges is in designing riser systems capable of overcoming the added risks of more severe environments, complicated well requirements and uncertainty of operating conditions. The failure of a primary riser component could lead to unacceptable consequences, including environmental damage, lost production and possible injury or loss of human life. Identification of the risks facing riser systems and management of these risks are essential to ensure that riser systems operate without failure. Operators have recognized the importance of installing instrumentation such as global positioning systems (GPS), vessel motion measurement packages, wind and wave sensors and Acoustic Doppler Current Profiler (ADCP) units to monitor vessel motions and environmental conditions. Additionally, high precision monitoring equipment has been developed for capturing riser response. Measured data from these instruments allow an operator to determine when the limits of acceptable response, predicted by analysis or determined by physical limitations of the riser components, have been exceeded. Regular processing of measured data through automated routines ensures that integrity can be quickly assessed. This is particularly important following extreme events, such as a hurricane or loop current. High and medium alert levels are set for each parameter, based on design analysis and operating data. Measured data is compared with these alert levels, and when an alert level is reached, further response evaluation or inspection of the components in question is recommended. This paper will describe the role of offshore monitoring in an integrity management program and discuss the development of alert levels based on potential failure modes of the riser systems. The paper will further demonstrate how this process is key for an effective integrity management program for deepwater riser systems.

scholarly journals Thermal and Chemical Integrity of Ru Electrode in Cu/TaOx/Ru ReRAM Memory Cell

2019 ◽  
Vol 8 (12) ◽  
pp. N220-N233
Author(s):  
Mohammad Al-Mamun ◽  
Sean W. King ◽  
Marius Orlowski
Keyword(s):  
Memory Cell ◽  
Operating Conditions ◽  
Electrical Performance ◽  
Pt Electrode ◽  
Switching Performance ◽  
Inert Electrode ◽  
Work Function Difference ◽  
The Impact ◽  
Si Wafer

A good candidate for replacing the inert platinum (Pt) electrode in the well-behaved Cu/TaOx/Pt resistive RAM memory cell is ruthenium (Ru), already successfully deployed in the CMOS back end of line. We benchmark Cu/TaOx/Ru device against Cu/TaOx/Pt and investigate the impact of embedment of Cu/TaOx/Ru on two different substrates, Ti(20nm)/SiO2(730nm)/Si and Ti(20nm)/TaOx(30nm)/SiO2(730nm)/Si, on the cell's electrical performance. While the devices show similar switching performance at some operating conditions, there are notable differences at other operation regimes shedding light on the basic switching mechanisms and the role of the inert electrode. The critical switching voltages are significantly higher for Ru than for Pt devices and can be partly explained by the work function difference and different surface roughness of the inert electrode. The poorer switching properties of the Ru device are attributed to the degraded inertness properties of the Ru electrode as a stopping barrier for Cu+ ions as compared to the Pt electrode. However, some of the degraded electrical properties of the Ru devices can be mitigated by an improved integration of the device on the Si wafer. This improvement is attributed to the suppression of crystallization of Ru and its silicidation reactions that take place at elevated local temperatures, present mainly during the reset operation. This hypothesis has been corroborated by extensive XRD studies of multiple layer systems annealed at temperatures between 300K and 1173K.

scholarly journals Synchronization of Thermoacoustic Modes in Sequential Combustors

2018 ◽  
Author(s):  
Giacomo Bonciolini ◽  
Nicolas Noiray
Keyword(s):  
Gas Turbines ◽  
High Amplitude ◽  
Operating Conditions ◽  
Operational Flexibility ◽  
Order Model ◽  
Thermoacoustic Instabilities ◽  
Physical Mechanisms ◽  
Sustained Oscillations ◽  
Engine Components

Sequential combustion constitutes a major technological step-change for gas turbines applications. This design provides higher operational flexibility, lower emissions and higher efficiency compared to today’s conventional architectures. Like any constant pressure combustion system, sequential combustors can undergo thermoacoustic instabilities. These instabilities potentially lead to high-amplitude acoustic limit cycles, which shorten the engine components’ lifetime and therefore reduce their reliability and availability. In case of a sequential system, the two flames are mutually coupled via acoustic and entropy waves. This additional inter-stages interaction markedly complicates the already challenging problem of thermoacoustic instabilities. As a result, new and unexplored system dynamics are possible. In this work, experimental data from our generic sequential combustor are presented. The system exhibits many different distinctive dynamics, as function of the operation parameters and of the combustor arrangement. This paper investigates a particular bifurcation, where two thermoacoustic modes synchronize their self-sustained oscillations over a range of operating conditions. A low-order model of this thermoacoustic bifurcation is proposed. This consists of two coupled stochastically driven non-linear oscillators, and is able to reproduce the peculiar dynamics associated with this synchronization phenomenon. The model aids in understanding what the physical mechanisms that play a key role in the unsteady combustor physics are. In particular, it highlights the role of entropy waves, which are a significant driver of thermoacoustic instabilities in this sequential setup. This research helps to lay the foundations for understanding the thermoacoustic instabilities in sequential combustion systems.

Somatic Value in Mechanical Products: Machines as Interactive Media

2009 ◽  
Author(s):  
Shuichi Fukuda
Keyword(s):  
Product Development ◽  
Mechanical Engineering ◽  
Interactive Media ◽  
Operating Conditions ◽  
Rational Approach ◽  
Traditional Role ◽  
The World ◽  
Mechanical Products ◽  
User Centric

This paper points out the importance of machines as tangible and substantial media for our customers to interact with the outer world. As the world is getting more and more globalized, diversified and complex, and situations are changing more frequently and extensively, it becomes harder and harder for designers to foresee operating conditions. Therefore design is changing quickly from traditional designer-centric to user-centric. It is a user who can understand the current situation and solve the imminent problem. Thus, the role of a machine is changing from a tool to a partner which helps a user understand the situation and solve the problem together. Although traditional role of machines has been primarily an actuator, its role as a sensing media is quickly increasing. Traditional product development has been one way and it is producer-driven, regarding customers as being very passive and just as consumers or users. But customers are very active and creative. The tangible and substantial feature of mechanical products has advantages in satisfying our customers’ needs for creativity and customization of our products to adapt to their needs and tastes and furthermore in creating experience and stories for them, which will add increased value, if not only product value but also process value is considered. To realize such goals, mechanical engineering should introduce more pragmatic approaches in addition to the current rational approach.

The role of real power output from farm tractor engines in determining their environmental performance in actual operating conditions

2020 ◽  
Vol 173 ◽  
pp. 105405
Author(s):  
Łukasz Rymaniak ◽  
Piotr Lijewski ◽  
Michalina Kamińska ◽  
Paweł Fuć ◽  
Beata Kurc ◽  
...  
Keyword(s):  
Power Output ◽  
Environmental Performance ◽  
Operating Conditions ◽  
Real Power ◽  
Farm Tractor ◽  
Actual Operating

scholarly journals Influence of Fiber Type on Fiberweb Properties in High-Speed Carding

2004 ◽  
Vol os-13 (2) ◽  
pp. 1558925004os-13
Author(s):  
N. B. Doguc ◽  
Abdelfattah M. Seyam ◽  
William Oxenham
Keyword(s):  
High Speed ◽  
Unit Area ◽  
Fiber Type ◽  
Fixed Number ◽  
Operating Conditions ◽  
Fiber Types ◽  
Novel Approach ◽  
General Data ◽  
Key Parameter

The performance of four different fiber types processed at two different carding speeds of 85 and 120 m/min, under fixed operating conditions, was assessed. The totally novel approach of fixing the fiber diameter was used in the experiments. To serve this purpose, we designed four different fibers. In addition, we fixed the number of fibers per unit area of the carded web so as to create constant carding conditions for all experimental fibers. The fixed number of fibers per unit area was achieved by carding the same number of fibers per unit time for a given speed. We took samples from different parts of the card and analyzed them in order to enumerate the effect of fiber type on cardability. Fiberweb uniformity was regarded as a key parameter for assessing the cardability. Several other web and fiber parameters were measured in order to augment the understanding of the role of fiber type in high-speed carding. In general, data revealed that fiberweb uniformity did not significantly differ among fiber types at the two carding speeds 85 m/min and 120 m/min.

scholarly journals Effect of change in role of an aircraft on engine life

2013 ◽  
Vol 117 (1196) ◽  
pp. 1053-1070
Author(s):  
A. Gad-Briggs ◽  
A. Haslam ◽  
P. Laskaridis
Keyword(s):  
Life Cycle ◽  
Life Cycle Cost ◽  
Low Cycle Fatigue ◽  
Operating Conditions ◽  
Significant Life ◽  
European Theatre ◽  
Harsh Climate ◽  
Performance Conditions ◽  
Dust Ingestion

Abstract New aircraft require years of development from concept to realisation and can be prone to delays. Consequently, military operators take existing fleets and operate them in a different role. The objective of this study is to examine the effect of operating a typical low bypass military fast jet engine, originally designed for a European theatre, in a hot and harsh climate. The specific purpose is to determine the effect on the high-pressure turbine blade life and the life- cycle cost of the engine. A mission profile and respective performance conditions were analysed and modelled using an in-house performance tool. The flow conditions were simulated using ANSYS® FLUENT. A conjugated heat transfer solution was adopted to determine the blade metal temperature. The blade was modelled physically in 3D using SIMULIA® ABAQUS FEA software. The stresses were derived and used to calculate the temperature coupled low cycle fatigue and creep life. A deterioration case was also studied to evaluate the effect of sand and dust ingestion. There was a significant life reduction of approximately 50% due to creep. The reduction in life was inversely proportional to the life cycle cost of the engine depending on the operating conditions. The results were compared with similar engines and summarised in the context of airworthiness regulations and component integrity.

Role of Failure-Mechanism Identification in Accelerated Testing

1993 ◽  
Vol 36 (4) ◽  
pp. 39-45
Author(s):  
J. Hu ◽  
D. Barker ◽  
A. Dasgupta ◽  
A. Arora
Keyword(s):  
Failure Mechanism ◽  
Failure Mechanisms ◽  
Electronic Devices ◽  
Operating Conditions ◽  
Accelerated Life Testing ◽  
Accelerated Testing ◽  
Normal Operating ◽  
Accelerated Life ◽  
Cut Method

Accelerated life testing techniques provide a short-cut method to investigate the reliability of electronic devices with respect to certain dominant failure mechanisms that occur under normal operating conditions. However, accelerated tests have often been conducted without knowledge of the failure mechanisms and without ensuring that the test accelerated the same mechanism as that obscrved under normal operating conditions. This paper summarizes common failure mechanisms in electronic devices and packages and investigates possible failure mechanism shifting during accelerated testing.

Paper 8: The Fundamentals of Lubrication Processes

1966 ◽  
Vol 181 (12) ◽  
pp. 32-38
Author(s):  
D. Dowson ◽  
J. A. Robertson
Keyword(s):  
Boundary Lubrication ◽  
Operating Conditions ◽  
Lubrication Conditions

The authors outline the fundamental aspects of lubrication conditions and distinguish between hydrodynamic, elastohydrodynamic, and boundary lubrication. The discussion is concerned with the physics rather than the mathematics. The important lubricant properties and the role of bearing geometry are considered. This discussion of modern views on lubrication is perfectly general but operating conditions encountered in textile machinery are considered so that the various types of lubrication in practice can be identified.

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