Design for Lifecycle Cost and Preventive Maintenance Using Time-Dependent Reliability

2010 ◽  
Vol 118-120 ◽  
pp. 10-16 ◽  
Author(s):  
Amandeep Singh ◽  
Zissimos P. Mourelatos ◽  
Jing Li
Keyword(s):  
Preventive Maintenance ◽  
Operating Conditions ◽  
Time Dependent ◽  
Variable Cost ◽  
System Response ◽  
Time Period ◽  
Engineering Requirement ◽  
Response Systems ◽  
Warranty Costs ◽  
The Cost

Reliability is an important engineering requirement for consistently delivering acceptable product performance through time. As time progresses, the product may fail due to time phenomena such as time-dependent operating conditions, component degradation, etc. The degradation of reliability with time may increase the lifecycle cost due to potential warranty costs, repairs and loss of market share. In design for lifecycle cost and preventive maintenance, we must account for product quality, and time-dependent reliability. Quality is a measure of our confidence that the product conforms to specifications as it leaves the factory. Reliability depends on 1) the probability that the system will perform its intended function successfully for a specified interval of time, and 2) on the probability that the system response will not exceed an objectionable by the customer or operator, threshold for a certain time period. Quality is time-independent, and reliability is time-dependent. This paper presents a methodology to determine the optimal design and preventive maintenance of time-dependent, multi-response systems, by minimizing the cost during the life of the product. The lifecycle cost includes a production, an inspection, and an expected variable cost. All costs depend on quality and/or reliability. A roller clutch example highlights the design methodology for lifecycle cost.

Design for Lifecycle Cost Using Time-Dependent Reliability

2010 ◽  
Vol 132 (9) ◽  
Author(s):  
Amandeep Singh ◽  
Zissimos P. Mourelatos ◽  
Jing Li
Keyword(s):  
Limit State ◽  
Probability Of Failure ◽  
Operating Conditions ◽  
Time Dependent ◽  
Variable Cost ◽  
Cumulative Probability ◽  
Vibratory System ◽  
Equivalent Time ◽  
Engineering Requirement ◽  
Warranty Costs

Reliability is an important engineering requirement for consistently delivering acceptable product performance through time. As time progresses, the product may fail due to time phenomena such as time-dependent operating conditions, component degradation, etc. The degradation of reliability with time may increase the lifecycle cost due to potential warranty costs, repairs, and loss of market share, affecting the sustainability of environmentally friendly products. In the design for lifecycle cost, we must account for product quality and time-dependent reliability. Quality is a measure of our confidence that the product conforms to specifications as it leaves the factory. Quality is time independent, and reliability is time dependent. This article presents a design methodology to determine the optimal design of time-dependent multiresponse systems by minimizing the cost during the life of the product. The conformance of multiple responses is treated in a series-system fashion. The lifecycle cost includes a production, an inspection, and an expected variable cost. All costs depend on quality and/or reliability. The key to our approach is the calculation of the so-called system cumulative probability of failure. For that, we use an equivalent time-invariant “composite” limit state and a niching genetic algorithm with lazy learning metamodeling. A two-mass vibratory system example and an automotive roller clutch example demonstrate the calculation of the cumulative probability of failure and the design for lifecycle cost.

Design for Lifecycle Cost Using Time-Dependent Reliability

2009 ◽  
Author(s):  
Amandeep Singh ◽  
Zissimos P. Mourelatos ◽  
Jing Li
Keyword(s):  
Distribution Function ◽  
Design Methodology ◽  
Cumulative Distribution Function ◽  
Limit State ◽  
Operating Conditions ◽  
Time Dependent ◽  
Cumulative Distribution ◽  
Variable Cost ◽  
System Response ◽  
Soft Failure

Reliability is an important engineering requirement for consistently delivering acceptable product performance through time. As time progresses, the product may fail due to time phenomena such as time-dependent operating conditions, component degradation, etc. The degradation of reliability with time may increase the lifecycle cost due to potential warranty costs, repairs and loss of market share. In design for lifecycle cost, we must account for product quality, and time-dependent reliability. Quality is a measure of our confidence that the product conforms to specifications as it leaves the factory. Reliability depends on 1) the probability that the system will perform its intended function successfully for a specified interval of time (no hard failure), and 2) on the probability that the system response will not exceed an objectionable by the customer or operator, threshold for a certain time period (no soft failure). Quality is time-independent, and reliability is time-dependent. This article presents a design methodology to determine the optimal design of time-dependent, multi-response systems, by minimizing the cost during the life of the product. The conformance of multiple responses is treated in a series-system fashion. The lifecycle cost includes a production, an inspection, and an expected variable cost. All costs depend on quality and/or reliability. The key to our approach is the calculation of the so-called system cumulative distribution function (time-dependent probability of failure). For that we use an equivalent time-invariant “composite” limit state which is accurate for monotonic or non-monotonic in time, systems. Examples highlight the calculation of the cumulative distribution function and the design methodology for lifecycle cost.

A Simulation-Based Random Process Method for Time-Dependent Reliability of Dynamic Systems

2010 ◽  
Author(s):  
Amandeep Singh ◽  
Zissimos P. Mourelatos ◽  
Efstratios Nikolaidis
Keyword(s):  
Random Process ◽  
Operating Conditions ◽  
Time Dependent ◽  
Process Time ◽  
Cumulative Probability ◽  
Repairable Systems ◽  
First Passage ◽  
True Value ◽  
Warranty Costs ◽  
Short Time

Reliability is an important engineering requirement for consistently delivering acceptable product performance through time. As time progresses, a product may fail due to time-dependent operating conditions and material properties, and component degradation. The reliability degradation with time may significantly increase the lifecycle cost due to potential warranty costs, repairs and loss of market share. In this work, we consider the first-passage reliability, which accounts for the first time failure of non-repairable systems. Methods are available that provide an upper bound to the true reliability, but they may overestimate the true value considerably. This paper proposes a methodology to calculate the cumulative probability of failure (probability of first passage or upcrossing) of a dynamic system with random properties, driven by an ergodic input random process. Time series modeling is used to characterize the input random process based on data from a “short” time period (e.g. seconds) from only one sample function of the random process. Sample functions of the output random process are calculated for the same “short” time because it is usually impractical to perform the calculation for a “long” duration (e.g. hours). The proposed methodology calculates the time-dependent reliability, at a “long” time using an accurate “extrapolation” procedure of the failure rate. A representative example of a quarter car model subjected to a stochastic road excitation demonstrates the improved accuracy of the proposed method compared with available methods.

Design Objectives and Experience With Processor Based Gas Turbine Controls

1984 ◽  
Author(s):  
Hans D. Lenz
Keyword(s):  
Control Systems ◽  
Gas Turbine ◽  
Preventive Maintenance ◽  
Operating Conditions ◽  
Operating Costs ◽  
Future Developments ◽  
Different Types ◽  
System Requirements ◽  
The Cost

This paper describes the control system requirements to reduce operating costs of gas turbine driven equipment, and the features and technologies available from up-to-date control systems to meet these requirements. Modern control systems can affect the cost of operation in the following areas: - Reduction of downtime. - Optimizing of performance during all operating conditions. - Long-term trending and failure diagnostics to maintain optimum efficiency and for preventive maintenance. Advances in electronic technology, especially microprocessors, make it possible to achieve improvements in these areas. Programming methods, an important tool in the application of this technology, are discussed. Applications of control systems are used to illustrate their effectiveness. Guidelines are presented to judge the value of different types of control systems in gas turbine and other applications and a look at future developments is presented.

CAD Of Anticorrosive Protection Of Steel Structures

2019 ◽  
pp. 18-23
Keyword(s):  
Protective Coating ◽  
Computer Aided Design ◽  
Steel Structures ◽  
Cost Effective ◽  
Operating Conditions ◽  
Computational Tool ◽  
Protection Method ◽  
Cost Effective Method ◽  
The Cost ◽  
Aided Design

The choice of cost-effective method of anticorrosive protection of steel structures is an urgent and time consuming task, considering the significant number of protection ways, differing from each other in the complex of technological, physical, chemical and economic characteristics. To reduce the complexity of solving this problem, the author proposes a computational tool that can be considered as a subsystem of computer-aided design and used at the stage of variant and detailed design of steel structures. As a criterion of the effectiveness of the anti-corrosion protection method, the cost of the protective coating during the service life is accepted. The analysis of existing methods of steel protection against corrosion is performed, the possibility of their use for the protection of the most common steel structures is established, as well as the estimated period of effective operation of the coating. The developed computational tool makes it possible to choose the best method of protection of steel structures against corrosion, taking into account the operating conditions of the protected structure and the possibility of using a protective coating.

Treatment system response to transient AOX (adsorbable organic halogen) loadings

1997 ◽  
Vol 35 (2-3) ◽  
pp. 85-91
Author(s):  
D. A. Barton ◽  
J. D. Woodruff ◽  
T. M. Bousquet ◽  
A. M. Parrish
Keyword(s):  
Paper Industry ◽  
Model Development ◽  
Operating Conditions ◽  
System Response ◽  
Additional Information ◽  
Organic Halogen ◽  
Aox Removal ◽  
Variable Operating Conditions ◽  
Plant Shutdown

If promulgated as proposed, effluent guidelines for the U.S. pulp and paper industry will impose average monthly and maximum daily numerical limits of discharged AOX (adsorbable organic halogen). At this time, it is unclear whether the maximum-day variability factor used to establish the proposed effluent guidelines will provide sufficient margin for mills to achieve compliance during periods of normal but variable operating conditions within the pulping and bleaching processes. Consequently, additional information is needed to relate transient AOX loadings with final AOX discharges. This paper presents a simplistic dynamic model of AOX decay during treatment. The model consists of hydraulic characterization of an activated sludge process and a first-order decay coefficient for AOX removal. Data for model development were acquired by frequent collection of influent and effluent samples at a bleach kraft mill during a bleach plant shutdown and startup sequence.

Optimal Placement of FACTS Devices for Voltage Stability Improvement with Economic Consideration Using Firefly Algorithm

2019 ◽  
Vol 14 (1) ◽  
pp. 5-11
Author(s):  
S. Rajasekaran ◽  
S. Muralidharan
Keyword(s):  
Power Systems ◽  
Voltage Stability ◽  
Firefly Algorithm ◽  
Transmission System ◽  
Operating Conditions ◽  
Optimal Placement ◽  
Voltage Collapse ◽  
Facts Devices ◽  
The Cost ◽  
Bus System

Background: Increasing power demand forces the power systems to operate at their maximum operating conditions. This leads the power system into voltage instability and causes voltage collapse. To avoid this problem, FACTS devices have been used in power systems to increase system stability with much reduced economical ratings. To achieve this, the FACTS devices must be placed in exact location. This paper presents Firefly Algorithm (FA) based optimization method to locate these devices of exact rating and least cost in the transmission system. Methods: Thyristor Controlled Series Capacitor (TCSC) and Static Var Compensator (SVC) are the FACTS devices used in the proposed methodology to enhance the voltage stability of power systems. Considering two objectives of enhancing the voltage stability of the transmission system and minimizing the cost of the FACTS devices, the optimal ratings and cost were identified for the devices under consideration using Firefly algorithm as an optimization tool. Also, a model study had been done with four different cases such as normal case, line outage case, generator outage case and overloading case (140%) for IEEE 14,30,57 and 118 bus systems. Results: The optimal locations to install SVC and TCSC in IEEE 14, 30, 57 and 118 bus systems were evaluated with minimal L-indices and cost using the proposed Firefly algorithm. From the results, it could be inferred that the cost of installing TCSC in IEEE bus system is slightly higher than SVC.For showing the superiority of Firefly algorithm, the results were compared with the already published research finding where this problem was solved using Genetic algorithm and Particle Swarm Optimization. It was revealed that the proposed firefly algorithm gives better optimum solution in minimizing the L-index values for IEEE 30 Bus system. Conclusion: The optimal placement, rating and cost of installation of TCSC and SVC in standard IEEE bus systems which enhanced the voltage stability were evaluated in this work. The need of the FACTS devices was also tested during the abnormal cases such as line outage case, generator outage case and overloading case (140%) with the proposed Firefly algorithm. Outputs reveal that the recognized placement of SVC and TCSC reduces the probability of voltage collapse and cost of the devices in the transmission lines. The capability of Firefly algorithm was also ensured by comparing its results with the results of other algorithms.

Stability of Ring-Type MEMS Gyroscopes Subjected to Stochastic Angular Speed Fluctuation

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Samuel F. Asokanthan ◽  
Soroush Arghavan ◽  
Mohamed Bognash
Keyword(s):  
Angular Velocity ◽  
Degrees Of Freedom ◽  
Microelectromechanical Systems ◽  
Damping Ratio ◽  
Operating Conditions ◽  
System Stability ◽  
System Response ◽  
Ring Type ◽  
Mems Gyroscopes ◽  
The Stability

Effect of stochastic fluctuations in angular velocity on the stability of two degrees-of-freedom ring-type microelectromechanical systems (MEMS) gyroscopes is investigated. The governing stochastic differential equations (SDEs) are discretized using the higher-order Milstein scheme in order to numerically predict the system response assuming the fluctuations to be white noise. Simulations via Euler scheme as well as a measure of largest Lyapunov exponents (LLEs) are employed for validation purposes due to lack of similar analytical or experimental data. The response of the gyroscope under different noise fluctuation magnitudes has been computed to ascertain the stability behavior of the system. External noise that affect the gyroscope dynamic behavior typically results from environment factors and the nature of the system operation can be exerted on the system at any frequency range depending on the source. Hence, a parametric study is performed to assess the noise intensity stability threshold for a number of damping ratio values. The stability investigation predicts the form of threshold fluctuation intensity dependence on damping ratio. Under typical gyroscope operating conditions, nominal input angular velocity magnitude and mass mismatch appear to have minimal influence on system stability.

Coordinate control of prostaglandin E2 synthesis and uptake by hyperosmolarity in renal medullary interstitial cells

2006 ◽  
Vol 290 (3) ◽  
pp. F641-F649 ◽  
Author(s):  
Michael L. Pucci ◽  
Shinichi Endo ◽  
Teruhisa Nomura ◽  
Run Lu ◽  
Cho Khine ◽  
...  
Keyword(s):  
Cell Surface ◽  
Characteristic Time ◽  
Water Deprivation ◽  
Interstitial Cells ◽  
Time Dependent ◽  
Prostaglandin E ◽  
Coordinate Control ◽  
Time Period ◽  
Cox 2 ◽  
Net Release

During water deprivation, prostaglandin E2 (PGE2), formed by renal medullary interstitial cells (RMICs), feedback inhibits the actions of antidiuretic hormone. Interstitial PGE2 concentrations represent the net of both PGE2 synthesis by cyclooxygenase (COX) and PGE2 uptake by carriers such as PGT. We used cultured RMICs to examine the effects of hyperosmolarity on both PG synthesis and PG uptake in the same RMIC. RMICs expressed endogenous PGT as assessed by mRNA and immunoblotting. RMICs rapidly took up [3H]PGE2 to a level 5- to 10-fold above background and with a characteristic time-dependent “overshoot.” Inhibitory constants ( Ki) for various PGs and PGT inhibitors were similar between RMICs and the cloned rat PGT. Increasing extracellular hyperosmolarity to the range of 335–485 mosM increased the net release of PGE2 by RMICs, an effect that was concentration dependent, maximal by 24 h, reversible, and associated with increased expression of COX-2. Over the same time period, there was decreased cell-surface activity of PGT due to internalization of the transporter. With continued exposure to hyperosmolarity over 7–10 days, PGE2 release remained elevated, COX-2 returned to baseline, and PGT-mediated uptake became markedly reduced. Our findings suggest that hyperosmolarity induces coordinated changes in COX-2-mediated PGE2 synthesis and PGT-mediated PGE2 uptake in RMICs.

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