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This study investigated the maximum tsunami heights corresponding to probable variances of fault parameters of earthquakes: strike, dip and slip angles. Numerical simulations were carried out with probable variance of these fault parameters based on four virtual tsunamis that could be triggered by a foreseeable future undersea earthquake off the western coast of Japan. Using this method, the maximum tsunami heights at Imwon Port were investigated. Furthermore, the relationship between the maximum tsunami heights and the fault parameters of earthquakes was evaluated for four virtual tsunamis. Mutual information, a measure of the dependence between two random variables, was introduced to identify relationships between them. The results indicated that strike angle showed more diverse maximum tsunami heights than the other fault parameters, while slip angle presented similar maximum tsunami heights. The strike angle was estimated to have the strongest relationship with the maximum tsunami height, regardless of the virtual tsunamis. [ABSTRACT FROM AUTHOR]

A practical method is proposed in this paper for analysis of the lightning transient in the grounding grids. The circuit parameters of the grounding electrodes are evaluated by a set of analytic formulas, in which the soil ionization effect is taken into account. By means of the circuit parameters, the grounding electrode segments are represented by the π‐type circuits and a circuit model is built for the grounding grids. The lightning transient responses in the grounding grids can be calculated from the circuit model. The calculated results are compared with the measured ones to check the validity of the circuit model. In view of the actual distribution randomness, the lightning current amplitude is taken as a random variable and a statistical algorithm is further presented for statistical analysis of the lightning transient in the grounding grids. In the algorithm, the accumulative probability function is introduced to describe the random distribution of the lightning current amplitude. The lightning transient responses calculated in a large interval of the lightning current amplitude are weighted by the corresponding probability density. Then, the statistical values of the lightning transient responses can be obtained from the weighted sum. A numerical example is also given to discuss the difference between the statistical values and the nonstatistical ones calculated by the conventional method. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In this paper we propose necessary conditions for antifragile project management, based on the Deming paradigm (a much richer version of statistical process control), named after W.E.Deming, who revolutionized the industry in Japan. We analyze in detail the concept of antifragility and extend it from probability theory to epistemology by proposing mechanisms that make a system antifragile, with application to knowledge as a complex system. These mechanisms are related with the internal dynamics of the system such as recursiveness, rather than the response to external stimuli. We built upon a previous work in which we propose quality of product or service as a payoff instead of short-term revenue. An antifragile project management strategy therefore means convexity of quality as a function of random events, uncertainty and lack of information, with quality itself being the random variable towards which the probability density distribution is locally convex. We propose Deming paradigms of management as necessary conditions in achieving antifragility of project management. They are related to the ability to extract the maximum of information from the smallest of errors – i) understanding variation ii) having a theory, iii) managing teams as complex systems. [ABSTRACT FROM AUTHOR]

The capacitive coupler is an attractive tool for on‐site partial discharge (PD) detection in a cable joint. To study its sensitivity characteristic, PDs in a 110‐kV prefabricated joint containing two artificial defects were detected successively using capacitive couplers with six different electrode widths installed at the same position of the cable. For the quantification of sensor sensitivity, the sensitivity factor is defined as the ratio of capacitive coupler output voltage amplitude to apparent charge that was determined through a conventional PD‐measuring circuit according to IEC 60270. As random variables, the sensitivity factors were displayed in the probability distribution plots for each capacitive coupler to visually compare their sensitivity levels. The results demonstrate an almost monotonically increasing dependence of sensitivity on the coupling electrode width, which agrees with the qualitative analysis based on the amplitude–frequency characteristic of the capacitive coupler. Besides, there is an obvious distinction in sensitivity factors between two distinct defects, indicating that the capacitive coupler is more suitable for PD trend analysis rather than apparent charge quantification. In addition, the insensitivity of the capacitive coupler to certain defect types may explain the cause of some undetectable dead zones in on‐site PD measurement. This study provides experimental support for the geometrical optimization of capacitive couplers. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

In risk assessment of spatially distributed infrastructure, the probability of demand exceeding capacity is evaluated across the system. We describe and compare two levee system reliability analysis frameworks for seismic and high-water demands. The first approach is general, but computationally intensive, and uses Monte Carlo simulations to model capacity and demand for "segments" (i.e., elemental levee lengths) as spatially correlated random variables. We apply a capacity correlation model derived from seismic case histories in Japan. The seismic demand correlation model is based on global ground motion data, whereas the high-water correlation is taken as unity. The second approach achieves computational efficiency by grouping segments into physics-based "reaches" (i.e., length of levee having uniform statistical distributions of capacity and demand). Statistics and spatial correlation of the limit state function are computed using a procedure based on the first-order reliability method. The probability of failure of the reach is then computed using level-crossing statistics. The application of level crossing statistics required an adjustment, introduced here, to previously utilized capacity correlation functions. We apply both methods for a levee system subjected to realistic demand and capacity distributions and show that characteristic lengths (defined as lengths of levee that can be considered as statistically independent) are comparable for high-water and seismic demands. This outcome is specific to the considered failure mechanisms and is driven by use of similar capacity correlation models, whereas differences in demand correlation models have limited impact. • The paper describes two levee system reliability analysis frameworks. • Both seismic and flood hazards are considered. • Gaussian correlations are developed for the level-crossing statistics method. • Characteristic lengths are compared for high-water and seismic demands. [ABSTRACT FROM AUTHOR]

Probabilistic optimal power flow (POPF) is an important tool in power system planning and operation. One limitation of conventional POPF is that only the probability information of random variables is obtained as a reference for related analyses. Frequency and duration information often plays an important role in power system assessment. In this study, a frequency and duration analysis method for POPF with wind farms (WFs) is proposed, which is based on Markov chains by improving the traditional probability‐frequency distribution function (PFDF) method. The main advantage of the proposed method is that highly accurate solutions can be obtained with less computation. Random input variables, including intermittent loads and WF power outputs associated with both wind speed uncertainties and wind turbine (WT) failures, are modeled using the corresponding PFDFs. With the proposed method, not only probability information but also frequency and duration information of random POPF outputs are efficiently and analytically computed through the operations of PFDFs of random inputs. Moreover, an optimization method for determining the clustering number of random states is proposed to improve the credibility of stochastic process modeling of Markov‐chain‐based random variables. The test on the modified IEEE‐RTS79 system with WFs demonstrates the rapidity and validity of the proposed method. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

While data are unavoidably missing or incomplete in most observational studies, consequences of mishandling such incompleteness in analysis are often overlooked. When time-varying information is collected irregularly and infrequently over a long period, even precisely obtained data may implicitly involve substantial incompleteness. Motivated by an analysis to quantitatively evaluate the effects of smoking and radiation on lung cancer risks among Japanese atomic-bomb survivors, we provide a unique application of multiple imputation to incompletely observed smoking histories under the assumption of missing at random. Predicting missing values for the age of smoking initiation and, given initiation, smoking intensity and cessation age, analyses can be based on complete, though partially imputed, smoking histories. A simulation study shows that multiple imputation appropriately conditioned on the outcome and other relevant variables can produce consistent estimates when data are missing at random. Our approach is particularly appealing in large cohort studies where a considerable amount of time-varying information is incomplete under a mechanism depending in a complex manner on other variables. In application to the motivating example, this approach is expected to reduce estimation bias that might be unavoidable in naive analyses, while keeping efficiency by retaining known information. [ABSTRACT FROM AUTHOR]

The ability to ascertain the extent of product sale fluctuations for each store and locality is indispensable to inventory management. This study analyzed POS data from 158 convenience stores in Kawasaki City, Kanagawa Prefecture, Japan and found a power scaling law between the mean and standard deviation of product sales quantities for several product categories. For the statistical domains of low sales quantities, the power index was 1/2; for large sales quantities, the power index was 1, so called Taylor’s law holds. The value of sales quantities with changing power indixes differed according to product category. We derived a Poissonian compound distribution model taking into account fluctuations in customer numbers to show that the scaling law could be explained theoretically for most of items. We also examined why the scaling law did not hold in some exceptional cases. [ABSTRACT FROM AUTHOR]

Factors and processes affecting community structures operate at various spatial and temporal scales. We analyzed how similarities of rocky intertidal assemblages vary at different spatial scales using a nested, hierarchical sampling design. Intertidal assemblages consisting of algae, sessile animals, and mobile animals were censused on five rock walls at each of five shores chosen within each of six regions along the Pacific coast of Japan, encompassing 1,800 km of coastlines. Based on this sampling design, similarities in assemblages were calculated using both qualitative (presence/absence) and quantitative (percent cover and density) data, and compared at three spatial levels: (1) rock level (the finest spatial scale, encompassing several to hundreds of meters), (2) shore level (the intermediate spatial scale, encompassing several to tens of kilometers), and (3) region level (the broadest spatial scale, encompassing hundreds to thousands of kilometers). Cluster analysis showed that assemblages were categorized into distinct regional groups except for the two southern regions, but they did not separate clearly from each shore. A nested analysis of similarities revealed significant variation in similarities among regions and among shores within each region, with the former showing greater variation. Similarity was negatively correlated with geographic distance at the regional level but not at the shore or the rock levels. At the regional level, similarity decreased more rapidly with distance for mobile animals than sessile organisms. The analyses highlighted the importance of broad-scale abiotic/biotic factors such as oceanic current conditions and biogeographic factors in determining observed patterns in similarity of rocky intertidal assemblages. [ABSTRACT FROM AUTHOR]

In the last decade, the real time ground–based geomagnetic observations realized in correlation with the Vrancea seismicity in Romania, together with supplementary studies related to some earthquakes (Mw9.0 Tohoku, Japan on 11 March 2011 and Mw8.3 Coquimbo, Chile on 16 September 2015), enlarged our knowledge about the relationship between the pre-seismic anomalous phenomena and the final stage of the earthquake nucleation. To identify possible ultra-low-frequency (ULF) geomagnetic signals prior to the onset of an Mw8.1 earthquake, we retroactively analyzed the data collected on the interval 1 August–16 September 2017 at the Geomagnetic Observatories in Teoloyucan (TEO), Mexico and Tucson (TUC) USA, with the last taken as a reference. Daily mean distributions of the polarization parameter BPOL (geomagnetic polarization parameter) and standard deviation are obtained for both observatories using a fast Fourier transform (FFT) band-pass filtering in the ULF range (0.001–0.083 Hz). Further on, we investigated the singularity of the pre-seismic signal associated with an Mw8.1 earthquake and applied a statistical analysis based on a standardized random variable equation; results are presented as BPOL* time series on the interval 1–26 September. Finally, the hourly mean distribution, obtained as difference BPOL (TUC-TEO) on the interval 7–9 September emphasizes an anomalous signal with five hours before the onset of the Mw8.1 earthquake. [ABSTRACT FROM AUTHOR]