Minimum Reliability Research Articles

Adult Malnutrition (Undernutrition) Screening: An Evidence Analysis Center Systematic Review

BackgroundMalnutrition screening relies on quick and easy-to-use tools that require minimal training of users. Valid and reliable tools should avoid under-referral of adults with a malnutrition diagnosis or over-referral of those without a malnutrition diagnosis to dietitians. ObjectiveOur aim was to conduct a systematic review of adult malnutrition screening tools for validity, agreement, and reliability, and to determine the costs of the malnutrition screening procedure. MethodsFollowing a structured process, a comprehensive search using PubMed, MEDLINE, EMBASE, and CINAHL was conducted for relevant research published between 1997 and 2017 that examined the validity, agreement, reliability, and costs of nutrition screening tools. ResultsSixty-nine studies met the inclusion criteria. The Malnutrition Screening Tool exhibited moderate validity, agreement, and reliability based on Grade I (Good/Strong) evidence. The evidence supporting the conclusions for the remaining tools was Fair (Grade II). The Malnutrition Universal Screening Tool exhibited high validity and moderate agreement and reliability. The Mini Nutritional Assessment–Short Form exhibited moderate validity and reliability and low agreement. The Short Nutritional Assessment Questionnaire and the Nutrition Risk Screening 2002 exhibited moderate validity and reliability and the Mini Nutritional Assessment–Short Form Body Mass Index exhibited high validity and moderate agreement. However, these last three tools were missing reliability or agreement data. Limited data were available to evaluate malnutrition screening costs. ConclusionsThis review provides an analysis of validity, agreement, and reliability of tools to screen adults for malnutrition, regardless of their age, medical history, or location. No tools were found with high validity, reliability, and strong supportive evidence. Tools most often achieved moderate validity, agreement, and reliability, and had large variations in individual results. The minimum validity and reliability of tools to screen adults for malnutrition should be established to shape future research. Cost data for the screening process should be obtained and examined.

Reliability analysis of deep underground research laboratory in Beishan for geological disposal of high-level radioactive waste

For underground engineering with complex structure, it is important to carry out reliability analysis to ensure engineering safety. This research takes China’s first underground research laboratory (URL) for the geological disposal of high-level radioactive waste (HLW) in Beishan area as engineering background. Firstly, based on a large number of drilling core data of Beishan site, the optimal probability distribution model of the rock mechanical parameters is established by statistical analysis. After that, a typical underground structure of the URL, which consists of a shaft and three intersecting tunnels at the depth of −560 m, is selected as research object. The reliability indexes of the structure are calculated by Response Surface-Monte Carlo method. The results show that after excavation, most of the reliability indexes of the structure are above 4.2. The structure is safe as a whole. Due to the interaction between different tunnels/shaft, the minimum reliability index appears at the intersecting corner of the tunnels/shaft, which indicates that the intersecting areas are the weakest area of the structure. The reliability calculation results are basically in good agreement with the geo-mechanical model test results, which verify the validity of the reliability calculation results.

On Stress-Strength Interval-System Reliability with Applications in Heart Conditions

The random variable X represents the stress placed on the system by the operating environment and random variable Y represents the strength of the system. A system is able to perform its intended function if its strength is greater than the stress imposed upon it. Reliability of the system is defined as the probability that the system is strong enough to overcome the stress. That is, R = P(Y >X). In other words, reliability is the probability that the strengths of the unit are greater than the stresses. The stress-strength model has found interests in many applications include mechanical engineering and human heart monitoring conditions. The interval-system is defined as a system with a series of chance events that occur in a given interval of time. A k-out-of-n interval-system is a system with a series of n events in a given interval of time which successes (or functions) if and only if at least k of the events succeed (function). In short, the k-out-of-n interval-system is an interval-system which successes if and only if at least k of n events succeeds. The stress-strength reliability inference of the interval-system with a series of n independent events that occurs in a given interval of time is considered. The reliability of the interval-system is the probability that at least k out of n events in a given interval of time succeed. This paper derives uniform minimum variance unbiased and maximum likelihood reliability estimates of k-out-of-n interval-system based on stress-strength inference events where X (stress) and Y (strength) are independent two-parameter exponential random variables. An application in human heart conditions to illustrate the results is discussed.

Design, optimisation and reliability allocation for energy systems based on equipment function and operating capacity

Designers of energy systems often face challenges in balancing the trade-off between cost and reliability. In literature, several papers have presented mathematical models for optimizing the reliability and cost of energy systems. However, the previous models only addressed reliability implicitly, i.e., based on availability and maintenance planning. Others focused on allocation of reliability based on individual equipment requirements via non-linear models that require high computational effort. This work proposes a novel mixed-integer linear programming (MILP) model that combines the use of both input-output (I-O) modelling and linearized parallel system reliability expressions. The proposed MILP model can optimize the design and reliability of energy systems based on equipment function and operating capacity. The model allocates equipment with sufficient reliability to meet system functional requirements and determines the required capacity. A simple pedagogical example is presented in this work to illustrate the features of proposed MILP model. The MILP model is then applied to a polygeneration case study consisting of two scenarios. In the first scenario, the polygeneration system was optimized based on specified reliability requirements. The technologies chosen for Scenario 1 were the CHP module, reverse osmosis unit and vapour compression chiller. The total annualized cost (TAC) for Scenario 1 was 53.3 US$ million/year. In the second scenario, the minimum reliability level for heat production was increased. The corresponding results indicated that an additional auxiliary boiler must be operated to meet the new requirements. The resulting TAC for the Scenario 2 was 5.3% higher than in the first scenario.

Validation of the Youth Efficacy/Empowerment Scale - Mental Health Finnish version.

Αdolescents face mental health problems and still their mental health needs are often neglected. Empowerment provides adolescents with the skills to impact their own lives and communities in general. The aim of the study is to examine the validity and reliability of the Finnish version of the Youth Efficacy/Empowerment Scale - Mental Health (YES-MH). Data was collected through an online questionnaire from pupils aged 12-17 years in Western Finland, comprised of the following instruments; the YES-MH, the Goodman's the Strengths and Difficulties Questionnaire (SDQ), and the Warwick-Edinburgh Mental Wellbeing Scale. Exploratory factor analysis was carried out to evaluate construct validity and disclose underlying structures which yielded the following subscales: Self, Services, System. The internal consistency of subscales was analyzed with Cronbach's α. Construct validity was further investigated by computing the Pearson's correlations coefficients between the subscales. Furthermore, correlations with SDQ and mental well-being dimensions were explored as measures of convergent validity. In the final model all items the Youth Efficacy/ Empowerment Scale - Mental Health were entered into the factor analysis. All factor loadings were more than 0.40, ranging from 0.63 to 0.89. All the scales exceeded the minimum reliability standard of 0.70 and all corrected item-total correlations were high. All the YES-MH subscales were significantly and positively correlated each other with correlations coefficients ranging from medium to high. Correlations of Mental Well-being score with Self and Services subscales were significant. Moreover, Self subscale was significantly correlated with all SDQ dimensions. Services subscale was significantly correlated with Emotional symptoms and total SDQ score, while System subscale was significantly correlated with Conduct problems. The exploratory factor analysis showed a clear factor structure and the results suggest that the YES-MH is a reliable scale for assessing empowerment among young people. The YES-MH can be useful for health professionals not only as an assessment tool but also when they need to evaluate mental health interventions and examine empowerment as an outcome. However, further research can provide insights for the use of the scale in specific adolescent target groups and among different ethnic groups as well.

Phase unwrapping method based on parallel local minimum reliability dual expanding for large-scale data

Considering data reliability, the optimized connections of dual residues for phase discontinuity reconstruction provide a more reliable scheme and produce more robust unwrapped results. However, their practical implementation usually involves a time-consuming iterative global operation, which is not suitable for application to the phase unwrapping (PU) of big blocks of interferometric synthetic aperture radar (InSAR) phase data. A parallel PU method based on local minimum reliability dual expanding is proposed. With given quality weight maps, the dual reliability is defined based on residues, and the minimum reliability residue pairs are introduced to represent possible discontinuous boundaries. We provide a dynamic expanding method for the pairs with local minimum reliability searching and dual merging. The final minimum balanced trees obtained are used for path integrating of PU with the aid of reliability maps. The calculation of reliability maps, the residue pair searching, and the dynamic expanding are designed to be carried out in parallel. We employ the interface propagation scheme based on the eikonal equation and flood-filling for the parallel implement. Two big blocks of airborne InSAR data were processed by the proposed method, the experimental results and analysis verified its robustness and efficiency for the large-scale PU problem.

Assessing rainwater harvesting systems and reliability analysis of storage tanks: a monitoring study and system simulation

AbstractThis study applied a simulation model to evaluate the reliability of rainwater harvesting systems (RWHs) and the potential for rainwater storage was investigated in three different buildings. The results indicated that the tank stores 97.7% of the run‐off from the gym roof. Modelling the volume of the tank connected to the gym roof showed that 100% reliability can not be achieved for a roof with a relatively small area. The reliability for a tank larger than 2600 L was independent of the size of the tank. Maximum reliability of the RWHs was 70% of the total days of the year for a tank volume of 10 000 L, 300 m2 roof area and daily demand of 300 L (60% demand). Minimum reliability was 3% of the total days of the year for a tank volume of 1000 L, 100 m2 roof area and a daily demand of 1000 L (80% demand).

Novel decoupling method for time-dependent reliability-based design optimization

Time-dependent reliability-based design optimization (RBDO) can provide the optimal design parameter solutions for the time-dependent structure, and thus plays a significant role in engineering application. Directly solving the time-dependent RBDO needs a nested double-loop optimization procedure, which undoubtedly leads to large computational costs. A novel decoupling method called two-step method (TSM) is proposed to efficiently solve the time-dependent RBDO. In the two-step method, the first step makes the minimum instantaneous reliability index satisfy the reliability target index by solving a transformed time-independent RBDO, and the second step performs time-dependent reliability analysis and deterministic optimization to obtain the optimal design parameters which meet the reliability target. Only a few time-dependent reliability analyses and several deterministic optimizations are involved in the proposed procedure; thus, the time-dependent RBDO can be efficiently solved. Several examples containing one numerical example and two engineering examples are introduced to show the effectiveness of the proposed TSM.

Resilient hybrid optical-RF backhauling for tiered networks

To meet the huge demand in 5G data services, it is expected to have an enormous number of small cells along the conventional base stations. Various backhaul links including Optical Fiber (OF), Free Space Optics (FSO) and Radio Frequency (RF) are used to support the backhaul demand of such tiered network. The objective of this paper is to improve the connectivity of tiered networks by obtaining the optimal combinations of backhauling technologies (OF, FSO, RF or hybrid FSO/RF). In this paper, optimization of two-tier networks connectivity and resilience is performed, under the constraints of minimum data rate, cost, and reliability of different links. Under realistic cost assumptions and linear relaxation, it was shown that the problem can be formulated as a convex optimization problem. In this paper, an iterative solution is proposed. The proposed solution iterates between two computationally efficient methods to successively maximize the algebraic connectivity and resilience. The simulation results show that the proposed algorithm can achieve gains of 240%−600% in terms of the network algebraic connectivity, depending on the rate constraint range. Similarly, it can achieve gains of 60%−100% enhancement in terms of the network resilience.

Modeling and optimization of a reliable blood supply chain network in crisis considering blood compatibility using MOGWO

Due to the prominent role of blood in human life, designing an efficient blood supply chain in case of an emergency situation is essential especially considering blood compatibility. This research proposes a multi-objective model for emergency blood supply chain management considering blood compatibility, routing, and location–allocation decisions. The blood supply chain network consists of donors, collection facilities, laboratories, blood centers, and hospitals. The mathematical model aims to minimize total supply chain cost and time while maximizing minimum reliability of established routes by making decisions regarding location–allocation, blood flow, inventory levels, and optimal routes. In order to solve the problem, a novel algorithm called Multi-Objective Grey Wolf Optimizer is used and compared to two classical algorithms Multi-Objective Particle Swarm Optimization and Non-dominated Sorting Genetic Algorithm-II. Performance of the algorithms is evaluated in various test problems using powerful measures. Also, the application of the proposed model is investigated in a case study in Iran’s capital, Tehran. Based on the results, important managerial insights are derived and optimal locations for facilities, inventory levels, routes and blood flow between facilities are determined.

Product reliability–oriented optimization design of time-between-events control chart system for high-quality manufacturing processes

In high-quality manufacturing processes, the yield is no more the only issue, and the quality control approach that also considers the product’s actual performance gradually becomes the focus. Reliability is a critical dimension of quality, and its degradation in usage is always determined by the manufacturing quality. To mitigate the degradation of reliability, this article presents a product reliability–oriented optimization design of the time-between-events control chart system, where the quantitative impact of process quality on the product reliability is analyzed. First, critical-to-reliability process parameters are identified, and a product reliability degradation model is proposed considering the effect of process variations and defects. Second, the observed event and the used statistics are determined to prearrange the time-between-events chart system. Third, all individual time-between-events charts are systematically optimized to minimize the expected batch product reliability degradation caused by potential process shifts, where the cost and statistical performance are considered as constraints. The result of the case study shows that the proposed design can reduce 27.02% of batch product reliability degradation due to manufacturing process quality, and this model can also save the operating cost on the basis of attaining minimum reliability degradation in certain situations.

ОПТИМИЗАЦИЯ МАРШРУТОВ ПРОКЛАДКИ МАГИСТРАЛЬНОГО ТРУБОПРОВОДА ДЛЯ ТРАНСПОРТИРОВКИ ГЕОРЕСУРСОВ

Актуальность исследования обусловлена необходимостью транспортировки добытого георесурса от месторождений до их переработки, с целью дальнейшего распределения между потребителями ресурсов различного назначения. В связи с этим актуальным является задача выбора маршрута прокладки магистрального трубопровода, осуществляющего транспортировку георесурсов от места добычи до мест их переработки. При этом должна быть обеспечена минимальность капитальных вложений и эксплуатационных затрат, а также надёжность функционирования магистрального трубопровода в условиях непредвиденных природно-техногенных воздействий. Цель: предложить новый метод для прокладки магистрального трубопровода, учитывающий совместимость или несовместимость различных типов трубопроводного транспорта в одном техническом коридоре, а также надежность их функционирования. Объекты: магистральный трубопровод, прокладываемый на заданной территории. Методы: методы теории графов и теории гиперсетей; методы эволюционного синтеза; компьютерное моделирование процесса транспортировки георесурсов; дискретизация области размещения магистрального трубопровода. Результаты. Предложен новый математический аппарат, основанный на модели теории гиперсетей, учитывающий иерархичность структуры проектируемого магистрального трубопровода. На основе гиперсетевого подхода получен новый метод прокладки магистрального трубопровода, учитывающий несовместимость различных типов ресурсов для прокладки в одном техническом коридоре. Разработан двухэтапный метод построения магистрального трубопровода, обеспечивающий минимальность капитальных вложений и эксплуатационных затрат. Кроме того, разработан модифицированный муравьиный алгоритм, обеспечивающий получение не только дешевого решения, но и достаточно надёжного по отношению к заданному порогу, при условии, что сбои происходят в первичной (физической) сети. В качестве показателя надёжности мы рассматриваем минимум среди всех парных вероятностей связности между каждым перерабатывающим пунктом и соответствующим источником. Полученные в ходе исследования численные эксперименты показывают применимость предложенных нами методов.

Analysis and Design of a Latency Control Protocol for Multi-Path Data Delivery With Pre-Defined QoS Guarantees

As the capacity and reliability of mobile networks increases, so does the demand for more responsive end-to-end services: applications such as augmented reality, live video conferencing, and smart or autonomous vehicles require reliable, throughput-intensive end-to-end communications with strict delay constraints. Only consistently reliable delivery of data flows well within human interactivity deadlines will enable a truly immersive user experience. To enable data delivery within pre-defined deadlines, controlled on demand by an application or its user, we propose and demonstrate a novel transport-layer protocol for explicit latency control called latency-controlled end-to-end aggregation protocol (LEAP). The LEAP splits a data flow with quality of service (QoS) constraints into multiple subflows that are delivered over multiple parallel links (e.g., Wi-Fi and LTE in a standard smartphone, WiGig, and 5G in the near future). The subflow data rates are set based on a novel proactive forecasting of the achievable channel capacity, subject to application-specific QoS constraints. Cross-path encoding and redundancy adaptation are then used to deliberately balance the trade-off between maximum throughput, required delay, and minimum reliability as function of application/user-specific input parameters. When compared to leading state-of-the-art transport protocols in live network experiments, LEAP exhibits a superior capacity to reliably provide a high and stable throughput with bounded latency, both in wired and wireless scenarios. The LEAP is also the first protocol to allow applications to explicitly set their priorities, giving them the freedom to set the operating point in the trade-off between throughput, latency, and reliability.

Optimum Consecutive Preventive Maintenance Scheduling Model Considering Reliability

As an effective means for improving system condition and reducing failures, a reasonable preventive maintenance scheduling guarantees the stability and safety of the system. This paper studies a consecutive maintenance scheduling problem for single-component systems with imperfect maintenance, and an optimum model with minimum reliability constraint for minimal cost rate is developed based on the renewal theory. The age-based and reliability-based maintenance strategies are modeled and compared according to a numerical example based on the degradation data of the actual system, which also verifies the optimality of the reliability-based strategy. At last, the influence of some key parameters is discussed by sensitive analysis.

Multi-objective optimisation of hybrid power systems under uncertainties

Hybrid power systems (HPSs) are a variant of distributed generation utilising two or more complementary energy sources for power generation, and are thus more efficient, reliable and cost-effective than single-source systems. HPSs can be used in urban, rural and remote areas. HPS research has focused on sizing and optimisation, which requires efficient and effective methodologies to ensure reliable power supply and a cost-effective system. This paper presents a mathematical programming technique for the design of off-grid and grid-connected HPSs, taking into account uncertainties in renewable energy resources and load demands. The basic model formulation is based on a comprehensive superstructure that includes all possible connections for power allocation. Chance-constrained programming is applied to determine the optimal capacities of power generation and energy storage units with a specified minimum system reliability level. Furthermore, fuzzy optimisation is adopted to account for the trade-off between conflicting economic and environmental goals, as well as parametric uncertainties in HPS design. Two case studies are presented to demonstrate the application of the proposed approach.

Probabilistic Characterization of an Allowable Design Moment in a Piping Elbow

The design of a nuclear power plant piping requires consideration of the effects of pressure and moment loads according to the appropriate design equation, which is Piping design equation (9) in NC/ND-3600, Section III of the ASME Boiler and Pressure Vessel Code. The design moment is influenced significantly by the definition of the B2 stress index in piping elbows. This paper presents a study on reliability-based design for piping elbows on the level D service limit in the design code. Probability density functions (PDFs) of the design moment were calculated using the ASME equation and modified B2 equations. The PDFs of the design moment were evaluated by the collapse moment using the closed-form equations. The probability distribution of the design moment using the modified B2 equation was closer to the distributions of the collapse moment than its design moment using the ASME B2 equation. Probabilistic analyses were conducted to evaluate reliability levels in straight pipe as well as piping elbows using the ASME and modified B2 equations. It was observed that the minimum reliability level (MRL) of the design equation for the straight pipe was slightly higher than the MRL of the elbow. The MRLs of the design equation using the ASME and modified B2 equations were similar for the same values of bend parameter h, and the MRL of the design equation did not show influence of changes in bend parameter, piping type, and B2 stress index.

A Reconfigurable High-Voltage Pulse Modulator with Full Discharge of the Pulse Forming Line

The electric circuit of a modulator at an output voltage up to 10 kV, allowing one to quickly, during a pause between pulses of about 2 ms, to change the pulse duration at a load of 10–30 μs is considered. For the possibility of increasing the pulse amplitude up to 60 kV using a pulsed transformer. At a pulse duration of more than 5 μs is most appropriate to use artificial forming lines based on discrete elements, capacitors and inductors, collected in the form of Γ-shaped LC chains. The pulse duration at the load is changed by changing the number of units of such chains forming a line, collected on a ladder diagram. “Soft” management switches, such as HiPakTM IGBT module switching thyristors, type 5SNA 0400J650100, voltage 6500 V, and a current 400 A, with the lowest possible internal resistance, are used. Computer simulation in the program allows one to optimize previously obtained results of calculation of the forming line assembled from l-shaped LC combinations for the specified load value of about 500 Ω. We performed model optimization of circuit elements and switches. The modeled parameters of components, from the point of view of obtaining a minimum cost and reliability while maintaining the specified electrical characteristics, are given. The EWB and Multisim software are best used.

Enhanced crow search algorithm for optimum design of structures

In this study, the capability of recently introduced crow search algorithm (CSA) was evaluated for structural optimization problems. It is observed that the standard CSA was led to undesirable performance for solving structural optimization problems. Accordingly, three modifications were made on the standard CSA to obtain the enhanced crow search algorithm (ECSA) while no parameter was added to the ECSA. First, each violated decision variable was replaced by corresponding decision variable of the global best solution. Second, a free-fly mechanism was suggested for constraint handling. Third, the personal upper bound strategy (PUBS) was proposed for elimination of inessential structural analyses. To assess the efficacy of the proposed modifications, four popular benchmark structures were employed and each modification was added to the CSA in a separate stage and then its effects were illustrated. The results of benchmark structures were examined in terms of minimum weight, convergence rate, and reliability. The results confirmed that the ECSA was significantly better than the standard CSA. Moreover, the ECSA obtained better or very competitive results in comparison with well-known and other newly developed metaheuristic methods.

Optimum LoRaWAN Configuration Under Wi-SUN Interference

Smart Utility Networks (SUN) rely on the Wireless-SUN (Wi-SUN) specification for years. Recently practitioners and researchers have considered Low-Power Wide-Area Networks (LPWAN) like LoRaWAN for SUN applications. With distinct technologies deployed in the same area and sharing unlicensed bands, one can expect these networks to interfere with one another. This paper builds over a LoRaWAN model to optimize network parameters while accounting for inter-technology interference. Our analytic model accounts for the interference LoRaWAN receives from IEEE 802.15.4g networks, which forms the bottom layers of Wi-SUN systems. We derive closed-form equations for the expected reliability of LoRaWAN in such scenarios. We set the model parameters with data from real measurements of the interplay among the technologies. Finally, we propose two optimization algorithms to determine the best LoRaWAN configurations, given a targeted minimum reliability level. The algorithms maximize either communication range or the number of users given constraints on the minimum number of users, minimum communication range, and minimum reliability. We validate the models and algorithms through numerical analysis and simulations. The proposed methods are useful tools for planning interference-limited networks with requirements of minimum reliability.

Hybrid Reliability-Based Design Optimization of Complex Structures With Random and Interval Uncertainties Based on ASS-HRA

In this paper, an efficient hybrid reliability analysis (HRA) method and a hybrid reliability-based design optimization (HRBDO) approach are proposed for realistic complex engineering structures with random and interval uncertainties. First, the HRBDO model for complex engineering structures is constructed with its objective and performance functions described as the implicit functions of design variables and random and interval parameters. Then, an efficient HRA method based on adaptive step size (ASS-HRA) is put forward to calculate the minimum reliability of the structure’s performance function under the influences of both random and interval uncertainties, the computational efficiency and accuracy of which are verified by a benchmark test. Subsequently, an efficient HRBDO approach integrating the proposed ASS-HRA method with the polynomial response surface model (PRSM) is developed for solving the HRBDO problems of complex engineering structures, the effectiveness of which is demonstrated by a numerical example. Finally, the HRBDO of a high-speed press slider demonstrates the efficiency, effectiveness, and versatility of the proposed HRBDO approach based on the ASS-HRA in the design of realistic complex engineering structures.