Failure-free Operations Research Articles

Power quality 24-hour prediction using differential, deep and statistics machine learning based on weather data in an off-grid

Prediction of Power Quality (PQ) on a daily basis is inevitable in planning Renewable Energy (RE) supply and scheduling the assumed power load in smart off-grid autonomous systems. Various combinations of the attached household appliances lead to specific operating states, related to the charge and load switching-time in different out-side conditions. Complexity and irregularities require modelling with the use of Artificial Intelligence (AI) to represent the uncertainty in load transitions and RE power oscillations. These specifics cannot be numerically solved with respect to unexpected states in detached micro-grid systems showing great variability. Recent Differential Learning, developed by the author, using a novel designed neuro-computing approach, enables one to model high non-linear and indefinable chaotic physical systems. The optimal training periods of day-set records were initially pre-assessed, based on AI input-output statistics. This model initialization allows operable day-ahead PQ-predictions in processing the last 24-hour series in one sequence. The proposed 2-level PQ-management evaluates initial load scheduling plans, based on available RE and storage sources. System efficiency and failure-free operations are planned considering the first estimate of its day-ahead PVP supply and secondary PQ verification of the provided load utilization schemes, under various state charges and RE production limits. This is a novelty with a notable incremental improvement in the published combinatorial optimization algorithms, only scheduling applicable load components, and reassessing the allowable power-day resources. Off-grid optimal operations can be determined and regulated by an adequate early morning PQ evaluation in RE utilization. A C++ parametric software, using differential learning to evolve PQ-models, historical PQ & meteo-data sets are at disposal to enable additional comparisons with the presented models.

A New Variant of JM Software Reliability Model

Software reliability is the probability of failure-free operations of software in a specific environment in a given time period. Various software reliability models have been designed by the researchers, but the JM model is the first influential model. The JM model was developed with the basic assumption that the faults are independent in this model and the debugging process is perfect. But practically, all debugging processes may not be perfect, especially when the faults are dependent; in this case, the fault that is actually to have been removed may also remove more than one fault and cause it to add some new faults. To handle this behavior of faults mutual dependency, we need a new model which may be less reliable or the result accuracy of the model may be lower than that of the existing ones, but it can handle more practical situations in the fault removal process. In this paper, we proposed a new software reliability model with the same assumption that at whatever time a failure is detected, it is not completely eradicated and there is a possibility of raising some new faults because of wrong analysis or inaccurate modifications in the software or the removal of the existing fault may also remove some other faults. The proposed model is more practical than the existing ones.

MANAGING TECHNOLOGY IN OIL PIPELINES INDUSTRY

This study identifies a few technology management issues of operating oil pipelines in oil industry and suggests an analytical framework to resolve those. This study focuses on the pipeline system design, pipeline coating selection, route selection, construction management, and pipeline inspection and maintenance issues. Operating oil pipelines in an optimum capacity through out its life, effective construction management and failure free operations are considered as critical success factors in oil transportation business. Operating oil pipelines in derated capacity due to deteriorating pipeline health or lack of demand, non-ability of augmenting pipeline capacity despite of demand, non-achievement of time, cost, and quality of pipeline construction projects, and many failures of pipelines despite of huge expenditure in inspection and maintenance are the common phenomena in oil pipelines industry. These not only cause business loss, but also increase stakeholders’ concerns for sustainable development. This study addresses the above issues using an analytical framework through stakeholders’ involvement. Keywords: Pipeline operations, technology management issues, analytical frameworks, group decision-making.

Flip-Chip (FC) and Fine-Pitch-Ball-Grid-Array (FPBGA) Underfills for Application in Aerospace Electronics—Brief Review

In this review, some major aspects of the current underfill technologies for flip-chip (FC) and fine-pitch-ball-grid-array (FPBGA), including chip-size packaging (CSP), are addressed, with an emphasis on applications, such as aerospace electronics, for which high reliability level is imperative. The following aspects of the FC and FPGGA technologies are considered: attributes of the FC and FPBGA structures and technologies; underfill-induced stresses; the roles of the glass transition temperature (Tg) of the underfill materials; some major attributes of the lead-free solder systems with underfill; reliability-related issues; thermal fatigue of the underfilled solder joints; warpage-related issues; attributes of accelerated life testing of solder joint interconnections with underfills; and predictive modeling, both finite-element-analysis (FEA)-based and analytical (“mathematical”). It is concluded particularly that the application of the quantitative assessments of the effect of the fabrication techniques on the reliability of solder materials, when high reliability is imperative, is critical and that all the three types of research tools that an aerospace reliability engineer has at his/her disposal, should be pursued, when appropriate and possible: experimental/testing, finite-element-analysis(FEA) simulations, and the “old-fashioned” analytical (“mathematical”) modeling. These two modeling techniques are based on different assumptions, and if the computed data obtained using these techniques result in the close output information, then there is a good reason to believe that this information is both accurate and trustworthy. This effort is particularly important for high-reliability FC and FPBGA applications, such as aerospace electronics, as the aerospace IC packages become more complex, and the requirements for their failure-free operations become more stringent.

Evaluating Software System Reliability Using Architecture Based Approach

Programming dependability is those failure-free programming operations for a specified time clinched alongside a specified earth. On acquire secondary unwavering quality to expansive what's more intricate framework, utilize architecture-based approach. Software reliability is one of the major attributes of the software quality attributes that are availability, interoperability, maintainability, manageability, performance, reliability, reusability. To obtain reliability, used mainly fault tolerance mechanisms in the design process. In this paper there is a comparison between error recovery along with fault tolerance mechanisms versus error propagation in evaluating software system reliability. Here compared two case studies which produce the software reliability.

Cost Optimization of SRGM using Genetic Algorithm

applications of computer systems have been increased immensely during the last few decades and the system reliability is major concern which is depends upon reliability of software and hardware components. Software testing is quality assurance process which confirms that the product is error free and reliable. The reliability of software is major quality attribute which ensure failure free operations and maintainability, therefore reliability assessment is necessary. Software reliability control the optimal release time and cost of software development. In this paper various fault detection and removal strategies are discussed to increase the reliability. A software reliability growth model with imperfect debugging based on Non-homogenous Position Process (NHPP) model is incorporated. The reliability estimation is based on testing and operational reliability of systems. The various numerical parameters are examined and results are presented with the GA tool of MATLAB for optimal release policy based on cost and reliability criterion.

An Enhanced Model for the Design of Tapered Sucker-Rod Strings

Summary A properly designed sucker-rod string should provide failure-free pumping operations for an extended period. Improper design of rod tapers can lead to early mechanical failures (rod breaks) with a complete termination of pumping action and an inevitable loss of production. Because of its prime importance in sucker-rod pumping technology, several rod-string-design procedures that are based on different assumptions were developed in the past. Because most sucker-rod breaks are fatigue failures, the mechanical design of a sucker-rod string must consider the cyclic nature of rod loading and the appropriate fatigue-endurance limit of the rod material. This is why most string designs use the modified Goodman diagram for calculating the lengths of rod tapers. Available sucker-rod-string design models calculate rod-taper lengths that ensure proper operation without premature fatigue failures. Their common design problems are (a) defining the principle of taper-length determination and (b) calculating the true mechanical stresses along the string. The universally accepted principle of taper-length calculations is to provide the same level of safety against fatigue failures in each taper section. Mechanical loads and stresses, on the other hand, are usually found in most of the design procedures from approximate formulas. These loads, therefore, can greatly deviate from the true mechanical loads that would be measured in the rod string run in the well. This paper details the main features of available rod-string designs and discusses their main characteristics; it provides a thorough comparison of designs involving the calculation of loads and stresses predicted from the solution of the damped-wave equation. By use of a predictive analysis program, rod stresses are calculated that (plotted on the modified Goodman diagram) provide a proper comparison of the merits of the different rod-string-design methods. Rod strings designed by available design procedures do not usually have identical safety included in the different tapers. This is because of the improper calculation of rod-string loads that form the basis of calculating rod-taper percentages. On the basis of the evaluation of the different available rod-string designs, the paper introduces a novel procedure that evaluates rod loads from the predictive solution of the damped-wave equation during the design process. Because loads calculated in this manner simulate actual loads with high accuracy, the most-important limitation of previous rod-string-design procedures is eliminated. Strings designed by use of the proposed model, therefore, will have identical safeties against fatigue failures in each taper; the new design model provides a much greater safety over previous designs.

Rollback-Recovery for Middleboxes

Network middleboxes must offer high availability, with automatic failover when a device fails. Achieving high availability is challenging because failover must correctly restore lost state (e.g., activity logs, port mappings) but must do so quickly (e.g., in less than typical transport timeout values to minimize disruption to applications) and with little overhead to failure-free operation (e.g., additional per-packet latencies of 10-100s of us). No existing middlebox design provides failover that is correct, fast to recover, and imposes little increased latency on failure-free operations. We present a new design for fault-tolerance in middleboxes that achieves these three goals. Our system, FTMB (for Fault-Tolerant MiddleBox), adopts the classical approach of "rollback recovery" in which a system uses information logged during normal operation to correctly reconstruct state after a failure. However, traditional rollback recovery cannot maintain high throughput given the frequent output rate of middleboxes. Hence, we design a novel solution to record middlebox state which relies on two mechanisms: (1) 'ordered logging', which provides lightweight logging of the information needed after recovery, and (2) a `parallel release' algorithm which, when coupled with ordered logging, ensures that recovery is always correct. We implement ordered logging and parallel release in Click and show that for our test applications our design adds only 30$\mu$s of latency to median per packet latencies. Our system introduces moderate throughput overheads (5-30%) and can reconstruct lost state in 40-275ms for practical systems.

A framework for safety automation of safety-critical systems operations

The more the risk level the lesser the safety and vice versa. The history of risk evaluation is moving from the point of accident investigation toward prior determination of quantum risk level. The risk level assessment is a part of risk evaluation process for identifying the risk aspects, impacts, hazard significance, and operational hazards. Risk assessment process helps for appropriate design of risk control procedures, to suggest provision of safety adequacy measures to reduce risk consequences, avoid or mitigate risks, and hazards. Risk free and failure free or fail-safe Operations in Safety-Critical Systems may not lead to loss of equipment, financial loss, environmental damage and hazard to human life. Prevailing standard techniques point out various risk factors and map out potential points where a safety critical operation can fail. The development of a framework is based on prevailing applicable standards and deals with safety–risk assessment for safety automation of safety-critical system operations. To explore various underlying risk factors, impacts and evaluation for determining risk magnitude, attributes and probabilities exhaustively considering practical conditions, a framework for safety automation of safety-critical operations is proposed. The methodology identifies underlying risk factors and determines risk significance for occupational and financial. Based on the identifications, a ten point scale to assess safety–risks is derived. The results of framework application to power plant case showed substantial improvement in assessing risks when compared to existing risk assessments. This is an indication of prevailing limited/inadequate safety–risk assessment in deeply addressing associated operational risks, proving the framework useful.

Classification of Post-deployment Performance Diagnostic Techniques for Large-scale Software Systems

Today's large-scale software systems (LSSs) such as Facebook, Google, Amazon and many other contemporary datacenters comprise hundreds or thousands of machines running complex applications that require high availability and responsiveness. These LSSs must be carefully monitored for performance bottlenecks before a serious harm is done. Performance analysts have to deal with the tedious task of monitoring the performance of these LSSs to avoid any service level agreements (SLA) violations and to ensure their failure free operations. There do exist several post-deployment performance diagnostic (PPD) techniques for to help analysts diagnose performance problems in the field, i.e., after the software is deployed. However, there is no classification of the proposed PPD techniques to understand their objectives and characteristics. In this paper, we classify the existing PPD techniques along multiple categories. The classification of PPD techniques will provide a guideline for performance analysts and practitioners of LSS to choose techniques suitable for their need. Moreover, the classification will also help researcher understand and fill gaps, i.e., dedicate their research efforts to categories that have received little attention in the past.

Extending the scope of the Checkpoint‐on‐Failure protocol for forward recovery in standard MPI

SUMMARYMost predictions of exascale machines picture billion ways parallelism, encompassing not only millions of cores but also tens of thousands of nodes. Even considering extremely optimistic advances in hardware reliability, probabilistic amplification entails that failures will be unavoidable. Consequently, software fault tolerance is paramount to maintain future scientific productivity. Two major problems hinder ubiquitous adoption of fault tolerance techniques: (i) traditional checkpoint‐based approaches incur a steep overhead on failure free operations and (ii) the dominant programming paradigm for parallel applications (the message passing interface (MPI) Standard) offers extremely limited support of software‐level fault tolerance approaches. In this paper, we present an approach that relies exclusively on the features of a high quality implementation, as defined by the current MPI Standard, to enable advanced forward recovery techniques, without incurring the overhead of customary periodic checkpointing. With our approach, when failure strikes, applications regain control to make a checkpoint before quitting execution. This checkpoint is in reaction to the failure occurrence rather than periodic. This checkpoint is reloaded in a new MPI application, which restores a sane environment for the forward, application‐based recovery technique to repair the failure‐damaged dataset. The validity and performance of this approach are evaluated on large‐scale systems, using the QR factorization as an example. Published 2013. This article is a US Government work and is in the public domain in the USA.

Average number of failure-free operations up to critical failure of a technologically dangerous facility: Calculation, limit and non-parametric estimates

For a technologically dangerous facility, critical failures which occur as a result of operations of an “on-off” type with frequent use, an indicator of “an average number of failure-free operations until a critical failure” is defined. For the indicator introduced, we determined a formula for its calculation, as well as limit and extrapolation estimates that are valid for any distribution law for failure-free operations of the facility.

Managing technology in oil pipelines industry

Operating oil pipelines in an optimum capacity through out its life, effective construction management and failure free operations are considered as critical success factors in oil transportation business. Operating oil pipelines in derated capacity due to deteriorating pipeline health or lack of demand, non-ability of augmenting pipeline capacity despite of demand, non-achievement of time, cost, and quality of pipeline construction projects, and many failures of pipelines despite of huge expenditure in inspection and maintenance are the common phenomena in oil pipelines industry. These not only cause business loss, but also increase stakeholders' concerns for sustainable development. This study addresses the above issues using an analytical framework through stakeholders' involvement. Copyright © 2006 Inderscience Enterprises Ltd.

Restoration scheme of mobility databases by mobility learning and prediction in PCS networks

This paper proposes a restoration scheme based on mobility learning and prediction in the presence of the failure of mobility databases in personal communication systems (PCSs). In PCSs, mobility databases must maintain the current location information of users to provide a fast connection for them. However, the malfunction of mobility databases may cause some location information to be lost. As a result, without an explicit restoration procedure, incoming calls to users may be rejected. Therefore, an explicit restoration scheme against the malfunction of mobility databases is needed to guarantee continuous service availability to users. Introducing mobility learning and prediction into the restoration process allows systems to locate users after a failure of mobility databases. In failure-free operations, the movement patterns of users are learned by a neuro-fuzzy inference system (NFIS). After a failure, an inference process of the NFIS is initiated and the users' future location is predicted. This is used to locate lost users after a failure. This proposal differs from previous approaches using a checkpoint because it does not need a backup process nor additional storage space to store checkpoint information. In addition, simulations show that our proposal can reduce the cost needed to restore the location records of lost users after a failure when compared to the checkpointing scheme.

Stochastic reliability growth

An assumption commonly made in early models of software reliability is that the failure rate of a program is a constant multiple of the number of faults remaining. This implies that all faults have the same effect upon the overall failure rate. The assumption is challenged and an alternative proposed. The suggested model results in earlier fault-fixes having a greater effect than later ones (the worst faults show themselves earlier and so are fixed earlier), and the DFR property between fault-fixes (confidence in programs increases during periods of failure-free operations, as well as at fault-fixes). The model shows a high degree of mathematical tractability, and allows a range of reliability measures to be calculated exactly. Predictions of total execution time to achieve a target reliability, and total number of fault-fixes to target reliability, are obtained. It is suggested that the model might also find applications in those hardware reliability growth situations where design errors are being eliminated.