Availability analysis of a LNG processing plant using the Markov process

2016 ◽  
Vol 22 (3) ◽  
pp. 302-320 ◽  
Author(s):  
Jakiul Hassan ◽  
Premkumar Thodi ◽  
Faisal Khan
Keyword(s):  
Markov Process ◽  
System Performance ◽  
Major Influence ◽  
Processing Plant ◽  
Alternative Mechanism ◽  
Markov Modeling ◽  
Markov Analysis ◽  
Content Type ◽  
Availability Analysis ◽  
State Dependent

Purpose – The purpose of this paper is to propose a state dependent stochastic Markov model for availability analysis of process plant instead of traditional time dependent model. Design/methodology/approach – The traditional concepts of system performance measurement and reliability (namely, binary; two-state concepts) are observed to be inadequate to characterize performance of complex system components. Availability analysis considering an intermediate state, such as a degraded state, provides a better alternative mechanism for system performance mapping. The availability model provides a better assessment of failure and repair characteristics for equipment in the sub-system and its overall performance. In addition to availability analysis, this paper also discusses the preventive maintenance (PM) program to achieve target availability. In this model, the degraded state is considered as a PM state. Using Markov analysis the optimum maintenance interval is determined. Findings – Markov process provides an easier way to measure the performance of the process facility. This study also revealed that the maintenance interval has a major influence in the availability of a process facility as well as in maintaining target availability. The developed model is also applicable to the varying target availability as well as having the capability to handle even the reconfigured process systems. Research limitations/implications – Considering the degraded state as an operative state, a higher availability of the plant is predicted. The consideration of the degraded state of the system makes the availability estimation more realistic and acceptable. Availability quantification, target availability allocation and a PM model are exemplified in a sub-system of an liquefied natural gas facility. Originality/value – The unique features of the present study are; Markov modeling approach integrating availability and PM; optimum PM interval determination of stochastically degrading components based on target availability; consideration of three-state systems; and consideration of increasing failure rates.

Multi-state failure phenomenon and analysis using semi-Markov model

2018 ◽  
Vol 35 (9) ◽  
pp. 2080-2091 ◽  
Author(s):  
Mahesh Narayan Dhawalikar ◽  
V. Mariappan ◽  
P.K. Srividhya ◽  
Vishal Kurtikar
Keyword(s):  
Markov Model ◽  
Weibull Distribution ◽  
Exponential Distribution ◽  
Failure Rate ◽  
Degradation Process ◽  
Markov Modeling ◽  
Content Type ◽  
Availability Analysis ◽  
Unique Approach ◽  
Reliability And Availability

Purpose Degraded failures and sudden critical failures are quite prevalent in industries. Degradation processes commonly belong to Weibull family and critical failures are found to follow exponential distribution. Therefore, it becomes important to carry out reliability and availability analysis of such systems. From the reported literature, it is learnt that models are available for the situations where the degraded failures as well as critical failures follow exponential distribution. The purpose of this paper is to present models suitable for reliability and availability analysis of systems where the degradation process follows Weibull distribution and critical failures follow exponential distribution. Design/methodology/approach The research uses Semi-Markov modeling using the approach of method of stages which is suitable when the failure processes follow Weibull distribution. The paper considers various states of the system and uses state transition diagram to present the transition of the system among good state, degraded state and failed state. Method of stages is used to convert the semi-Markov model to Markov model. The number of stages calculated in Method of stages is usually not an integer value which needs to be round off. Method of stages thus suffers from the rounding off error. A unique approach is proposed to arrive at failure rates to reduce the error in method of stages. Periodic inspection and repairs of systems are commonly followed in industries to take care of system degradation. This paper presents models to carry out reliability and availability analysis of the systems including the case where degraded failures can be arrested by appropriate inspection and repair. Findings The proposed method for estimating the degraded failure rate can be used to reduce the error in method of stages. The models and the methodology are suitable for reliability and availability analysis of systems involving degradation which is very common in systems involving moving parts. These models are very suitable in accurately estimating the system reliability and availability which is very important in industry. The models conveniently cover the cases of degraded systems for which the model proposed by Hokstad and Frovig is not suitable. Research limitations/implications The models developed consider the systems where the repair phenomenon follows exponential and the failure mechanism follows Weibull with shape parameter greater than 1. Practical implications These models can be suitably used to deal with reliability and availability analysis of systems where the degradation process is non-exponential. Thus, the models can be practically used to meet the industrial requirement of accurately estimating the reliability and availability of degradable systems. Originality/value A unique approach is presented in this paper for estimating degraded failure rate in the method of stages which reduces the rounding error. The models presented for reliability and availability analyses can deal with degradable systems where the degradation process follows Weibull distribution, which is not possible with the model presented by Hokstad and Frovig.

Availability analysis of distillery plant using petri nets

2018 ◽  
Vol 35 (10) ◽  
pp. 2373-2387 ◽  
Author(s):  
Ankur Bahl ◽  
Anish Sachdeva ◽  
Rajiv Kumar Garg
Keyword(s):  
Petri Nets ◽  
Dynamic Behavior ◽  
Point Of View ◽  
Plant Production ◽  
Maintenance Policy ◽  
Markov Analysis ◽  
Content Type ◽  
Availability Analysis ◽  
Critical Machine ◽  
Network Fault

Purpose The purpose of this paper is to prepare a methodology to evaluate availability analysis of distillery plant using Petri nets (PN). The effect of various failures, repair rate and availability of repair facilities on the system has been studied. Design/methodology/approach The PN model of a system is developed to study the dynamic behavior of the system under various working conditions. Availability analysis of the plant is presented taking into consideration of failure and repair rates of their subsystems and has been carried out using Monte Carlo simulation. Findings The bottle washing machine is the most critical machine from a maintenance point of view which has more compact on the system performance as compared to other machines. The availability analysis of distillery plant helps the management to adopt a suitable maintenance policy to improve upon plant production and plant availability. Originality/value The application of this proposed PN-based approach is very useful in finding the most critical subsystem and its effect on the performance of the system in terms of availability and plant production. Further, the advantage of the PN approach is that dynamic behavior of the system under consideration is modeled with graphic representation of the system and given distribution can be associated with the subsystems for analysis. The superiority of this approach over others, such as network, fault tree and Markov analysis, is outlined in the paper.

scholarly journals Occurrence of Antimicrobial-Resistant Escherichia coli and Salmonella enterica in the Beef Cattle Production and Processing Continuum

2014 ◽  
Vol 81 (2) ◽  
pp. 713-725 ◽  
Author(s):  
John W. Schmidt ◽  
Getahun E. Agga ◽  
Joseph M. Bosilevac ◽  
Dayna M. Brichta-Harhay ◽  
Steven D. Shackelford ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Salmonella Enterica ◽  
Generation Cephalosporin ◽  
Resistant Bacteria ◽  
Processing Plant ◽  
Cattle Production ◽  
Content Type ◽  
E Coli ◽  
Beef Processing ◽  
Tract Infections

ABSTRACTSpecific concerns have been raised that third-generation cephalosporin-resistant (3GCr)Escherichia coli, trimethoprim-sulfamethoxazole-resistant (COTr)E. coli, 3GCrSalmonella enterica, and nalidixic acid-resistant (NALr)S. entericamay be present in cattle production environments, persist through beef processing, and contaminate final products. The prevalences and concentrations of these organisms were determined in feces and hides (at feedlot and processing plant), pre-evisceration carcasses, and final carcasses from three lots of fed cattle (n= 184). The prevalences and concentrations were further determined for strip loins from 103 of the carcasses. 3GCrSalmonellawas detected on 7.6% of hides during processing and was not detected on the final carcasses or strip loins. NALrS. entericawas detected on only one hide. 3GCrE. coliand COTrE. coliwere detected on 100.0% of hides during processing. Concentrations of 3GCrE. coliand COTrE. colion hides were correlated with pre-evisceration carcass contamination. 3GCrE. coliand COTrE. coliwere each detected on only 0.5% of final carcasses and were not detected on strip loins. Five hundred and 42 isolates were screened for extraintestinal pathogenicE. coli(ExPEC) virulence-associated markers. Only two COTrE. coliisolates from hides were ExPEC, indicating that fed cattle products are not a significant source of ExPEC causing human urinary tract infections. The very low prevalences of these organisms on final carcasses and their absence on strip loins demonstrate that current sanitary dressing procedures and processing interventions are effective against antimicrobial-resistant bacteria.

Modeling multi-state system reliability analysis in a power station under fatal and nonfatal shocks: a simulation approach

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mohammad Reza Pourhassan ◽  
Sadigh Raissi ◽  
Arash Apornak
Keyword(s):  
Reliability Analysis ◽  
System Reliability ◽  
System Performance ◽  
Failure Process ◽  
State System ◽  
Failure Behavior ◽  
Simulation Approach ◽  
Critical System ◽  
Content Type ◽  
System Reliability Analysis

PurposeIn some environments, the failure rate of a system depends not only on time but also on the system condition, such as vibrational level, efficiency and the number of random shocks, each of which causes failure. In this situation, systems can keep working, though they fail gradually. So, the purpose of this paper is modeling multi-state system reliability analysis in capacitor bank under fatal and nonfatal shocks by a simulation approach.Design/methodology/approachIn some situations, there may be several levels of failure where the system performance diminishes gradually. However, if the level of failure is beyond a certain threshold, the system may stop working. Transition from one faulty stage to the next can lead the system to more rapid degradation. Thus, in failure analysis, the authors need to consider the transition rate from these stages in order to model the failure process.FindingsThis study aims to perform multi-state system reliability analysis in energy storage facilities of SAIPA Corporation. This is performed to extract a predictive model for failure behavior as well as to analyze the effect of shocks on deterioration. The results indicate that the reliability of the system improved by 6%.Originality/valueThe results of this study can provide more confidence for critical system designers who are engaged on the proper system performance beyond economic design.

Hygiene behavior assessment of a hazelnut processing plant

2019 ◽  
Vol 121 (2) ◽  
pp. 400-410 ◽  
Author(s):  
Rinaldo Botondi
Keyword(s):  
Indoor Air ◽  
Design Methodology ◽  
Reference Data ◽  
Processing Plant ◽  
Content Type ◽  
Hygiene Behavior ◽  
Microbiological Parameters ◽  
Processing Line ◽  
Bacteria And Fungi ◽  
Microbial Groups

PurposeThe purpose of this paper is to evaluate the possible microbiological contamination in terms of total counts and representative microbial groups found in the hazelnuts as well as in work areas and on the working surfaces of a hazelnut processing plant.Design/methodology/approachSome microbiological parameters related to the manufacturing process (e.g. aerobic colony count yeast and fungi) were evaluated. Indoor air samples were tested in order to evaluate the possible contamination of fungal strains (i.e. mycotoxin producing fungi).FindingsThe results showed that the highest values (>of 500 CFU/m3) for bacteria and fungi were only observed in the shelling and sorting areas. Some species such as Aspergillus and Penicillium (potential mycotoxin-producers) as well as some noxious colonies ofAspergillus fumigatuswere detected along the processing line. No occurrence of aflatoxins was observed in the finished product. Microbial loads obtained through surface analyses were in accordance to the reference data.Originality/valueThe aim of this study was to monitor and improve the procedures currently used in a hazelnut processing plant.

Design and fabrication of a lower limb exoskeleton to assist in stair ascending

2019 ◽  
Vol 46 (2) ◽  
pp. 290-299 ◽  
Author(s):  
Payman Joudzadeh ◽  
Alireza Hadi ◽  
Bahram Tarvirdizadeh ◽  
Danial Borooghani ◽  
Khalil Alipour
Keyword(s):  
Lower Limb ◽  
System Performance ◽  
Design Methodology ◽  
Stair Climbing ◽  
Robot Design ◽  
Disabled People ◽  
Content Type ◽  
Lower Limb Exoskeleton ◽  
Knee Braces ◽  
Novel Design

Purpose This paper aims to deal with the development of a novel lower limb exoskeleton to assist disabled people in stair ascending. Design/methodology/approach For this purpose, a novel design of a mixture of motors and cables has been proposed for users to wear them easily and show the application of the system in stair climbing. Findings One of the prominences of this study is the provided robot design where four joints are actuated with only two motors; each motor actuates either the knees or ankles. Another advantage of the designed system is that with motors placed in a backpack, the knee braces can be worn under clothes to be concealed. Finally, the system performance is evaluated using electromyography (EMG) signals showing 28 per cent reduction in energy consumption of related muscles. Originality/value This investigation deals with the development of a novel lower limb exoskeleton to assist disabled people in stair ascending.

Introducing multivariate Markov modeling within QFD to anticipate future customer preferences in product design

2018 ◽  
Vol 35 (3) ◽  
pp. 762-778 ◽  
Author(s):  
Katerina Gotzamani ◽  
Andreas Georgiou ◽  
Andreas Andronikidis ◽  
Konstantina Kamvysi
Keyword(s):  
Quality Function Deployment ◽  
Fuzzy Ahp ◽  
Markov Modeling ◽  
Design Decisions ◽  
Content Type ◽  
Customer Preferences ◽  
First Time ◽  
The Voice ◽  
Product Specifications

Purpose The purpose of this paper is to provide an enhanced version of quality function deployment (QFD) that captures customers’ present and future preferences, accurately prioritizes product specifications and eventually translates them into desirable quality products. Under rapidly changing environments, customer requirements and preferences are constantly changing and evolving, rendering essential the realization of the dynamic role of the “Voice of the Customer (VoC)” in the design and development of products. Design/methodology/approach The proposed methodological framework incorporates a Multivariate Markov Chain (MMC) model to describe the pattern of changes in customer preferences over time, the Fuzzy AHP method to accommodate the uncertainty and subjectivity of the “VoC” and the LP-GW-AHP to discover the most important product specifications in order to structure a robust QFD method. This enhanced QFD framework (MMC-QFD-LP-GW-Fuzzy AHP) takes into consideration the dynamic nature of the “VoC” captures the actual customers’ preferences (WHATs) and interprets them into design decisions (HOWs). Findings The integration of MMC models into the QFD helps to handle the sequences of customers’ preferences as categorical data sequences and to consider the multiple interdependencies among them. Originality/value In this study, a MMC model is introduced for the first time within QFD, in an effort to extend the concept of listening to further anticipating to customer wants. Gaining a deeper understanding of current and future customers’ preferences could help organizations to design products and plan strategies that more effectively and efficiently satisfy them.

Identification of Crp as a novel regulator of the Std fimbrial expression in Salmonella

Microbiology ◽  
2021 ◽  
Author(s):  
Karine Dufresne ◽  
France Daigle
Keyword(s):  
Wild Type Strain ◽  
Distal Region ◽  
Transcriptional Factor ◽  
Major Influence ◽  
Wild Type ◽  
Content Type ◽  
Link Type ◽  
Serovar Typhimurium ◽  
Metabolic Regulators

The Salmonella enterica serovar Typhi genome contains 14 putative fimbrial systems. The Std fimbriae belong to the chaperone-usher family and its regulation has not been investigated in S. Typhi. Several regulators of Std were previously identified in the closely related serovar Typhimurium. We hypothesize that regulators of S. Typhimurium may be shared with S. Typhi, but that several other regulators remain to be discovered. Here, we describe the role of more than 50 different candidate regulators on std expression. Three types of regulators were investigated: known regulators in S. Typhimurium, in silico predicted regulators and virulence/metabolic regulators. Expression of std was determined in the regulator mutants and compared with the wild-type strain. Overall, 21 regulator mutations affect std promoter expression. The role of Crp, a newly identified factor for std expression, was further investigated. Crp acted as an activator of std expression on a distal region of the std promoter region. Together, our results demonstrate the major influence of Crp as a novel transcriptional factor on std promoter expression and later production of Std fimbriae in Salmonella .

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