Calculation Of Reliability Indices Research Articles

Assessment of Psychometric Properties of the Postpartum Bonding Questionnaire (PBQ) in Jordanian Mothers

Background: Mother to infant bonding is the most important process in the puerperium, where many instruments have been designed to screen for mother-infant bonding issues. In this study, we will translate and validate the Postpartum Bonding Questionnaire (PBQ) to the Arabic and to measure the mother-infant bonding in a sample of Jordanian mothers.Materials and methods: This sample is a representative sample taken from multiple centers in Amman, Jordan. Post-partum lady who give a birth to a live healthy baby, regardless the mood of the delivery, who have been discharged with their babies home. Women with multiple pregnancies were also included. We calculated reliability indices and relevant statistics using SPSS.Results: A total of 120 participants included in this study. The mean age for the included sample was 28.1 (±6.3) years. Scale internal consistency measured via Cronbach’s alpha is 0.720. Average intraclass correlation coefficient for single measure is 0.067 (CI 0.045 to 0.097). Mean score for the 4 factors of the questionnaire were: Factor 1: 17.43 (±3.95), factor 2: 4.10 (±3.98), factor 3: 7.99 (±2.39), factor 4: 0.37 (±0.94).Conclusion: We translated and validated an Arabic version of the Postpartum Bonding Questionnaire (PBQ), an easy and widely used instrument to measure mother-infant bonding disorders. We observed a high frequency of bonding disorder among a Jordanian sample.

An Enhanced Algebraic Approach for the Analytical Reliability Assessment of Distribution Systems

The calculation of standard reliability indices is critical for assessing quality service and guiding the planning and operation of distribution systems. Traditionally, such calculation has relied on the application of analytical methods based on simulation techniques, which preclude the use of exact methodologies when reliability assessment is incorporated into operation and planning models. This shortcoming has been recently addressed by the development of two optimization-based approaches for the analytical reliability assessment of distribution systems. Unfortunately, both methods are either incomplete or computationally expensive as compared with those based on simulation. In order to overcome these issues, this paper presents a novel and efficient algebraic approach to calculate the standard network-dependent reliability indices of distribution systems. As a distinctive feature over previous non-simulation-based methods, no optimization process is involved. Thus, the proposed approach relies on the solution of a set of linear equations for which effective algorithms are available. Several benchmarks including a real-life 1080-node system have been used to demonstrate the computational superiority of the proposed method. The successful numerical experience supports the suitability of the proposed algebraic model for reliability-constrained distribution system operation and planning.

AN ENGINEERING RELIABILITY ANALYSIS METHOD BASED ON ADAPTIVE METAMODELS

In practical engineering problems, numerical analyses using the finite element (FE) method or other methods are generally required to evaluate system responses including stresses and deformations. For problems involving expensive FE analyses, it is not efficient or straightforward to directly apply conventional sampling-based or gradient-based reliability analysis approaches. To reduce computational efforts, it is useful to develop efficient and accurate metamodeling techniques to replace the original FE analyses. In this work, an adaptive metamodeling technique and a First-Order Reliability Method (FORM) were integrated. In each adaptive iteration, a compactly supported radial basis function (RBF) was adopted and a metamodel was created to explicitly express a performance function. An alternate FORM was implemented to calculate reliability index of the current iteration. Based on the design point, additional samples were generated and added to the existing sample points to re-generate the metamodel. The accuracy of the RBF metamodel could be improved in the neighborhood of the design point at each iteration. This procedure continued until the convergence of the reliability analysis results was achieved. A numerical example was studied. The proposed adaptive approach worked well and reliability analysis results were found with a reasonable number of iterations.

Fast analytical method for reliability evaluation of electricity-gas integrated energy system considering dispatch strategies

Reliability assessment of electricity-gas integrated energy system is undertaken via a new analytical method in this paper. Firstly, reliability models of coupling devices are developed to quantify interdependences between power distribution system and gas distribution system. Afterwards, reliability is evaluated separately in the two subsystems considering their distinctions in operation characteristics. A new topology simplification approach is presented to calculate reliability indices of natural gas system while reliability of power distribution system is evaluated based on the shortest path method. Finally, a practical case combined a 10 kV feeder of distribution station in Guangdong with Belgain natural gas network is exploited to verify the effectiveness and practicability of the proposed method.

Analytical model for fast reliability evaluation of composite generation and transmission system based on sequential Monte Carlo simulation

This paper proposes an analytical reliability evaluation (RE) model for composite generation and transmission system (CGTS) based on the sequential Monte Carlo simulation (MCS) method. The main idea is to partition the chronological system state sequence produced by sequential MCS into a set of mutually exclusive events based on the law of total probability. An analytical model is developed by extracting the component reliability parameters (CRPs) from system reliability index calculation formula of each mutually exclusive event. Once the proposed model is established, system reliability indices with variable CRPs can be obtained directly, rather than repeatedly performing the time-consuming sequential MCS process. In addition, sensitivity coefficients of system reliability indices with respect to CRPs can be obtained using the developed analytical model. A 4-unit generation system, the CGTS of IEEE-RTS system and a 91-bus power system are used for case study to validate the correctness and effectiveness of the proposed analytical RE model.

Development of a Reliability Index Considering Flood Damage for Urban Drainage Systems

Urban drainage systems are used to safely drain rainwater and prevent urban inundation, and their reliability is usually calculated from the probability of failure, which includes the probability of the drainage facilities being destroyed. This study proposes a new reliability index that includes three factors (flood volume, nodes, and damage), with the aim of prioritizing the structural and nonstructural measures required to improve urban drainage systems. In this study, synthetic rainfall data are generated by the Huff distribution and are used as input data for runoff simulations. The Distance Measure Method that uses a utopian approach is employed here to generate a dimensionless reliability index, as the three factors use different units and no definitive criteria currently exist to determine the weights that should be assigned to each factor. The reliability indexes of flood volume, nodes, and damage determined in this study are 0.7226, 0.4584 and 0.9750, respectively, as the three factors are weighted equally in the reliability index calculation. Using the new method, the reliability index of the city of Jeongup is 0.6484. The new reliability index can be used to assess the effectiveness of various flood mitigation measures in preparation for extreme rainfall events.

Study on the reliability of the carrying capacity of static pressure pipe piles in Shenyang

On the basis of the previous work, combined with the test piles collected from Shenyang area, this paper makes a detailed study of the current standard single safety factor design pile base method to the probability limit state design pile base method. The main work is statistical analysis, calculation of reliability index, analysis of the main factors affecting the reliability index of static pressure pipe pile and the analysis of its sub-coefficient coefficients, the reliability of its carrying capacity analysis has made a useful exploration.

Reliability Evaluation of Smart Distribution Systems Considering Load Rebound Characteristics

Load rebound characteristics (LRC), which means that restoration of distribution systems with large thermostatically controlled load (TCL) after an outage may create significantly higher load demand than normal (namely the demand if this outage does not occur), will make the reliability index—expected energy not supplied (EENS) of distribution systems obtained by traditional methods pessimistic and inaccurate. Since EENS is one of the base points of investment planning for distribution system operator, it is necessary to consider the LRC in the reliability evaluation and provide a more accurate evaluation on EENS. This paper proposed a new reliability evaluation method of smart distribution systems based on a nonnegative k-singular value decomposition (NN-K-SVD) algorithm and a sequential Monte Carlo (SMC) simulation. The NN-K-SVD algorithm is used to identify the TCL in total load. A reliability model considering the LRC is established based on an electric water heater model. The SMC simulation is used to mimic the operation of distribution systems based on the established reliability evaluation model, and calculate reliability indices. Furthermore, the feasibility of the proposed method is validated by extensive cases studies.

Validity Test and Reliability of Indonesian Language Multiple Choice in Final Term Examination

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Determining load-carrying capacity and remaining lifetime of bridge in Vitanova, Slovakia

The paper is focused on diagnostic and calculation of load-carrying capacity of bridge object in village Vitanova in Slovakia. The bridge is on the road II/520 connecting town Tvrdošín and village Suchá Hora near border with Poland and bypass the Oravica River. The bridge object was built in 1957, so, it was 60 years old bridge in time of calculation (2017). It is reinforced concrete slab bridge of two single independent spans. In 2016, the Department of Structures and Bridges, the Faculty of Civil Engineering, University of Žilina, was asked to carry out the construction and technical survey and diagnostic of above mentioned bridge. The visual inspection, diagnostic, verifying real dimensions and material characteristics were requested. In 2017, the calculation of load-carrying capacity was done. For determining the load-carrying capacity, the standard approach given in Eurocodes was used. As an alternative, the modified (lower) reliability levels and their adequate partial safety factors according to Eurocodes were used. Moreover, the real traffic load was used for calculation of reliability index β and the failure probability Pf.

An Incremental Reliability Assessment Approach for Transmission Expansion Planning

Reliability assessment is of great importance to transmission expansion planning (TEP). In this paper, a novel incremental reliability assessment approach (IRAA) for TEP is proposed. The basic idea is to build an incremental reliability indices calculation model so as to quantitatively estimate the degree of reliability enhancement with high computational efficiency. First, contingencies are categorized into three scenarios according to the states of the added components of the planning schemes. Then, contribution of each scenario to the incremental reliability indices is analyzed in detail. It turns out that contingencies of only one scenario can affect the incremental reliability indices and, therefore, other contingencies can be eliminated. Based on this phenomenon, an IRAA is developed for TEP, which can be used to improve the performance of various traditional reliability assessment methods. Case studies are performed on IEEE RTS 24-bus and IEEE 300-bus test system. The results demonstrate that the IRAA has superior performance to traditional methods in terms of accuracy and efficiency.

Analytical and Reliability Study of the Tunnel with Rockbolts in Rock Masses

Rockbolts are a critical reinforcement ways which widely used in tunnel engineering. In this paper, an analytical solution of circular tunnel with rockbolts was proposed based on homogenization method, and then the stability of a circular tunnel was investigated by considering the uncertainty based on the proposed analytical solution. Elastoplastic analytical solution for unsupported circular tunnel was presented briefly in hydrostatic stress field with a linear Mohr-Coulomb yield criterion and a non-associated flow rule. An analytical solution of circular tunnel with rockbolts was proposed through considering rock mass and rockbolts as a new homogeneous, isotropic, parameters strengthened equivalent composite material. A numerical example is used to verify the proposed analytical solution. The results show that the proposed solution can effectively characterize the mechanical behavior of rock mass and rockbolts in tunnel. Then, the proposed solution is adopted to calculate reliability index and failure probability of tunnel. The results show that the proposed method can also be effectively used to perform the stability and reliability analysis of tunnel and rockbolts have an important effect on plastic zone size and displacement of tunnel.

Assessment of Reliability Levels and Adjustment of Load-resistance Factors Using Optimization for Gravitational Loads-governed Limit States of the AASHTO LRFD Bridge Design Specifications

This paper presents the reliability levels provided by the load-resistance factors of the AASHTO LRFD Bridge Design Specifications for the Strength Limit State-I and -IV, and an optimization scheme for adjusting the load-resistance factors of the specifications. It is shown that the load-resistance factors of the specifications result in lower reliability indices than the target reliability index and widely varying reliability indices with the load composition for reinforced concrete, steel and pre-stressed concrete members. An optimization scheme is proposed to obtain a new set of the load-resistance factors that yield more uniform reliability levels and better approximation to the target reliability index in a wide range of load compositions. The objective function of the proposed optimization scheme is defined as the L2-norm of the error between the target and calculated reliability indices by load-resistance factors over a given interval of load composition. The results of the optimization show that the dead load factor for structural components should be increased by 0.1 for the Strength Limit State-I, and that the vehicular live load should be included in the Strength Limit State-IV. The use of exact figures up to the second decimal point is recommended for the resistance factors. A unified limit state for gravitational loads is proposed to replace the two limit states with a single limit state.

Capacity value estimation of wind power incorporating hourly wind speed

Purpose The purpose of this paper is to show the effect of randomness of wind speed on the capacity value estimation of wind power. Three methods that incorporate hourly wind speed have been evaluated. Design/methodology/approach Wind speed is simulated using autoregressive moving average method and is included in the calculation of reliability index as a negative load on an hourly basis. The reliability index is calculated before and after the addition of wind capacity. Increment of load or alteration of conventional capacity will lead to capacity estimation. Findings Among the aforementioned three methods, the former two exclude the availability rate and give the exact value for wind capacity addition. The third method is based on the availability rate and provides a little higher capacity value, indicating a clear correlation between availability and capacity value. Originality/value The methods that exclude the availability rate show consistent results. By including the availability rate, the third method predicts the inverse relation between the availability rate and the capacity value.

ЭНЕРГЕТИЧЕСКИЕ СИСТЕМЫ СУДОВЫХ ДИЗЕЛЬНЫХ ЭНЕРГЕТИЧЕСКИХ УСТАНОВОК: ОБОСНОВАНИЕ ТРЕБОВАНИЙ К НАДЕЖНОСТИ

The article touches upon reliability issues of energy management systems (EMS) of marine power plants in emergency situations caused by disturbance of the working media consumption and their subsequent recovery. The mathematical model of processes allows to determine the nature of changes in temperature and pressure of water and lube oil in EMS systems. The requirements to the characteristics of automatic control systems of the marine power plant have been formulated. Basic provisions of the reliability theory are followed by presentation of methods of calculating reliability indices of complex technical systems. The article presents the results of the study of non-stationary modes and reliability indices. Reasonable requirements for automated control systems were obtained through the analysis of working environments and of equipment operating in non-stationary modes, non-exceedance of safety limits of marine power plant operation being taken as the admissibility criterion. Besides, there are possible special modes resulted from emergency situations caused by the power plant equipment failure. Hence, for operation and design of the analyses it is important to study changes of working media in the circulation systems, which resulted from the failure of the pumps. Basic circuit of lubrication and cooling systems of the ship diesel power plants has been approved as recommended by the company "MAN B&W" for slow speed diesel engines standard series MC. Among the recommended schemes there was approved the scheme of the main engine with an autonomous cooling circuit. Schematic diagram of energy systems of a diesel power plant has been made under recommendations of the engine developer. Specifications of the component parts of the ship diesel power plant have been taken as standard for manufactured machinery. A low running L90MC-C four-cylinder main engine manufactured by "MAN B&W" was chosen as a research sample. A mathematical model, as applied to the given problem, consists of 10 algebraic equations for nonsteady working media consumption and 18 differential equations for nonsteady heat transfer in heat exchangers, as well as equations for transport delay in the lubrication systems of internal combustion engines.

Evaluation of Smart Grid Technologies Employed for System Reliability Improvement: Pacific Northwest Smart Grid Demonstration Experience

The Pacific Northwest Smart Grid Demonstration (PNWSGD) was a smart grid technology performance evaluation project that included multiple U.S. states and cooperation from multiple electric utilities in the northwest region. One of the local objectives for the project was to achieve improved distribution system reliability. Toward this end, some PNWSGD utilities automated their distribution systems, including the application of fault detection, isolation, and restoration and advanced metering infrastructure. In light of this investment, a major challenge was to establish a correlation between the implementation of these smart grid technologies and the actual improvements of distribution system reliability. This paper proposes using Welch's t-test to objectively determine and quantify whether distribution system reliability is improving over time. The proposed methodology is generic, and it can be implemented by any utility after calculation of the standard reliability indices. The effectiveness of the proposed hypothesis testing approach is demonstrated through comprehensive practical results. It is believed that wider adoption of the proposed approach can help utilities to evaluate a realistic long-term performance of smart grid technologies.

High dimensional model representation for reliability analyses of complex rock–soil slope stability

The high-dimensional model representation (HDMR) and its modifications, the fractional HDMR (FHDMR) and hybrid HDMR (HHDMR), are new tools for calculating reliability indexes in stability analyses when several variables with large uncertainties are used to describe rock and soil behaviours. Plain HDMR utilises an inverse reliability analysis for the study of unknown design parameters associated with target reliability index values. This approach uses implicit response functions, named limit state functions, according to the response surface method (RSM). In this study, both the FHDMR and HHDMR are applied to the reliability index calculation of safety factors related to the stability analyses of sliding failure mechanisms in complex formations. These two methods improve the computational efficiency of the RSM in reliability index calculations compared to the HDMR. A case study of Carpathian Flysch rock–soil slopes is presented, and the efficiency of the reliability index calculation is estimated by comparing results with ones from neural network application.

Analysis of Time-dependent Reliability of Durability in Concrete Member Under Ordinary Atmospheric Environment

According to the Chinese and foreign durability research reference of concrete members, this paper established an calculation method for time-dependent reliability index of durability in concrete members, and made an calculation of time-dependent reliability index under 50 year’s service life under normal atmosphere condition for typical concrete members. According to the crack width calculation in GB 50010-2010, the influence of concrete cover on the reliability index of durability and crack width in concrete members were studied, and some suggestion in code revision about crack calculation was made.

Loss of Load Probability Calculation for West Java Power System with Nuclear Power Plant Scenario

Loss of Load Probability (LOLP) index showing the quality and performance of an electrical system. LOLP value is affected by load growth, the load duration curve, forced outage rate of the plant, number and capacity of generating units. This reliability index calculation begins with load forecasting to 2018 using multiple regression method. Scenario 1 with compositions of conventional plants produce the largest LOLP in 2017 amounted to 71.609 days / year. While the best reliability index generated in scenario 2 with the NPP amounted to 6.941 days / year in 2015. Improved reliability of systems using nuclear power more efficiently when compared to conventional plants because it also has advantages such as emission-free, inexpensive fuel costs, as well as high level of plant availability.

Reliability Based Analysis and Optimum Design of Laterally Loaded Piles

In this study reliability based limit analysis is used to determine the ultimate capacity of laterally loaded piles. The aim of this study is to evaluate the lateral load capacity of free-head and fixed-head long pile when plastic limit analysis is considered. In addition to the plastic limit analysis to control the plastic behaviour of the structure, uncertain bound on the complementary strain energy of the residual forces is also applied. This bound has significant effect for the load parameter. The solution to reliability-based problems is based on a direct integration technique and the uncertainties are assumed to follow Gaussian distribution. The optimization procedure is governed by the reliability index calculation.