Comment on “Free surface tension in incompressible smoothed particle hydrodynamics (ISPH)” [Comput. Mech. 2020, 65, 487–502]

We comment on a recent article [Comput. Mech. 2020, 65, 487–502] about surface-tension modeling for free-surface flows with Smoothed Particle Hydrodynamics. The authors motivate part of their work related to a novel principal curvature approximation by the wrong claim that the classical curvature formulation in SPH overestimates the curvature in 3D by a factor of 2. In this note we confirm the correctness of the classical formulation and point out the misconception of the commented article.

Shi'ism Revisited

Contemporary Muslims face the challenge of how a legal system that was formulated in the classical period of Islam can respond to the multitudinous challenges that present-day Muslims encounter. Is there a need for reformation in Islam? If so, where should it begin and in which direction should it proceed? Addressing this gap in Western scholarship, and contributing to the ongoing debate in Islamic scholarship, Shi‘ism Revisited: Ijtihad and Reformation in Contemporary Times (1) explores how modernity has impinged on the classical formulation of Islamic law, and (2) analyzes how Shi‘i jurists have responded to the intersection of shari’a (Islamic law) and modernity. The study is original and groundbreaking in that it seeks to tackle issues such as how Islamic law is being revised by Shi‘i scholars on cases such as human rights, gender equality, the rights of non-Muslim minorities, and reconfiguring the rational and moral basis of Islamic law. Such questions have required scholars to apply ijtihad (independent reasoning) in providing solutions to the pressing questions in the religious and social fields. By examining the principles and application of Islamic legal theory (usul al-fiqh) and reformation in Shi‘ism, as well as the current discourse on juristic hermeneutics and the basis of a new ijtihad, this research addresses topics that have attracted much public attention. Since such issues have been largely neglected by Western scholarship, this book provides a unique analysis of ijtihad and reformation in the Shi‘i world.

On guarantee optimization in control problem with finite set of disturbances

In this paper, we deal with a control problem under conditions of disturbances, which is stated as a problem of optimization of the guaranteed result. Compared to the classical formulation of such problems, we assume that the set of admissible disturbances is finite and consists of piecewise continuous functions. In connection with this additional functional constraint on the disturbance, we introduce an appropriate class of non-anticipative control strategies and consider the corresponding value of the optimal guaranteed result. Under a technical assumption concerning a property of distinguishability of the admissible disturbances, we prove that this result can be achieved by using control strategies with full memory. As a consequence, we establish unimprovability of the class of full-memory strategies. A key element of the proof is a procedure of recovering the disturbance acting in the system, which allows us to associate every non-anticipative strategy with a full-memory strategy providing a close guaranteed result. The paper concludes with an illustrative example.

On rapidly oscillating solutions of a nonlinear elliptic equation

The aim of this article is to examine the solutions of the boundary value problem of the nonlinear elliptic equation ε 2△u = f(u). We describe the asymptotic behavior as ε tends to zero of the solutions on a spherical crown C of RN , (N ≥ 2) in a direct non-classical formulation which suggests easy proofs. We propose to look for interesting solutions in the case where the condition at the edge of the crown is a constant function. Our results are formulated in classical mathematics.Their proofs use the stroboscopic method which is a tool of the nonstandard asymptotic theory of differential equations.

Dynamics and Strength of Housings and Supporting Elements of Hydrogenerator Design

The basic designs of Hydrogenerators are considered in the presented scientific work. It is shown that one of the most loaded units of Hydrogenerator is the thrust bearing. The analysis of the causes of emergencies in the thrust bearing unit of the high power Hydrogenerator is performed based on the experience of operation. Cause-and-effect relations of origin and development of defects are determined. Existing methods of calculation of the stressed state of the chambers of the thrust bearing unit in the classical formulation for the stationary mode of operation are considered. The main features of the thrust bearing unit operation with respect to the features of the sliding supports were studied. An updated Diagram of the sliding supports loading is presented. For the first time, the calculation of the elastic chambers of the thrust bearing was performed in three-dimensional formulation taking into account the physical properties of the oil, the material of the chambers and the unevenness of the existing loads. It is shown that the applied designs of SE “Рlant “Electrotyazhmash” can be used in high power Hydrogenerators in the entire range of operational loads without restrictions.

Research on Nonlinear Deformation and Stability of an Aircraft Fuselage Composite Section under Transverse Bending

Currently, there is a lack of studies on the strength and stability of reinforced composite shells, taking into account the momentness and nonlinearity of the initial stress-strain state. Most of the known solutions to the shells stability problems are obtained by analytical and numerical methods, as a rule, in the linear approximation, i.e. in the classical formulation. A developed technique is proposed implementing the finite element method for solving the problems of strength and stability of discrete-reinforced cylindrical shells made of the composite material, taking into account the momentness and nonlinearity of their subcritical stress-strain state. The transverse bending stability of the reinforced aircraft fuselage compartment made of composite material has been investigated. The effect of deformation nonlinearity, stiffness of stringer set, shell thickness on critical loads of the shell instability has been determined.

Pharmacognostical and Physico-chemical Evaluation of Ativishadi Churna – An Ayurvedic Formulation

Ativishadi churna is a traditional classical formulation pioneered by the science of Ayurveda. The very first reference regarding the formulation was documented in the Charka Samhita under title Ativishadi Yoga. The main indication of this formulation is to cure diarrhoea due to pitta dosha vitiation. It contains an equal part of powdered and dried Ativisha roots, Kutaj bark and Indrayava (dried Kutaj seeds). The polyherbal formulations comprise a wide range of bioactive compounds and the standardization of such formulations is a great concern these days. Hence, the present study evolves around standardizing Ativishadi Churna, for this purpose physicochemical parameters were performed of individual drugs by keeping the values of API as a standard. A complete pharmacognostic profile of ingredients has been validated to authenticate plant materials and to confirm the absence of any adulterants or impurities in the formulation. The preliminary phytochemical tests, Pharmacognostic and phytochemical standardization of the formulation were performed as a part of an SOP development. The formulation besides has been proven to possess antimicrobial properties against pathogens responsible for common infectious diseases in humans. The recent concern lies in the fact that some traditional medicines have been claimed to possess heavy metals. For this purpose, the heavy metal content has also been determined which shows that the formulation is devoid of heavy metals that may cause toxicity. The pharmacognostic and phytochemical study of this formulation would be very important for establishing standards in the future.

Dynamic formation of a safety corridor during preliminary vessel route planning

В статье рассматривается процесс предварительной прокладки судна. Показаны подходы к процессу, а также современное состояние дел. В результате делается промежуточный вывод о том, что современная система коридоров безопасности может быть не совсем адекватна в реальных условиях использования с системами искусственного интеллекта. Сделана классическая постановка задачи выбора элементов планирования пути. Были рассмотрены факторы, влияющие на безопасность, и поставлены 2 задачи. Первая связана с подбором элементов и оценкой их отдельного влияния на риски и безопасность. Выведены две формулы, позволяющие оценить коэффициенты, характеризующие точку поля, где идёт судно. В рамках второй задачи рассчитаны примерные графики величин. График рисков из-за близости к опасности был построен разложением на соотвествующие дискреты. При этом, график целесообразности нахождения в пространстве был сделан для плеча в 10 миль с максимальным отклонением в полмили. Показан совершенно разный темп падения/роста параметров. Как следствие, показана их сочетаемость. The article deals with the process of preliminary plotting of a vessel's route. Approaches to the process are shown, as well as the current state of Affairs. As a result, an intermediate conclusion is made that the modern system of security corridors may not be quite adequate in real conditions of use with artificial intelligence systems. The classical formulation of the problem of selecting elements of path planning is made. Factors affecting safety were considered and 2 tasks were set. The first is related to the selection of elements and the assessment of their individual impact on risks and security. Two formulas are derived that allow us to estimate the coefficients that characterize the point of the field where the ship is going. In the second task, approximate graphs of values are calculated. The risk graph due to proximity to the hazard was constructed by decomposing it into the appropriate discrete values. At the same time, the graph of the expediency of being in space was made for a leg of 10 miles with a maximum deviation of half a mile. A completely different rate of decline/growth of parameters is shown. As a result, their compatibility is shown.

Sequence-based hazard analysis for Italy considering a grid seismic source model

Earthquakes are usually clustered in both time and space and, within each cluster, the event of highest magnitude is conventionally identified as the mainshock, while the foreshocks and the aftershocks are the events that occur before and after it, respectively. Mainshocks are the earthquakes considered in the classical formulation of the probabilistic seismic hazard analysis (PSHA), where the contribution of foreshocks and aftershocks is usually neglected. In fact, it has been shown that it is possible to rigorously, within the hypotheses of the model, account for the effect of mainshock-aftershocks sequences by means of the sequence-based PSHA (i.e., SPSHA). SPSHA extends the usability of the homogeneous Poisson process, adopted for mainshocks within PSHA, to also describe the occurrence of clusters maintaining the same input data of PSHA; i.e., the seismic rates derived by a declustered catalog. The aftershocks’ occurrences are accounted for by means of conditional non-homogeneous Poisson processes based on the modified Omori law. The seismic source model for Italy has been recently investigated, and the objective of the study herein presented is to include and evaluate the effect of aftershocks, by means of SPSHA, based on a new grid model. In the paper, the results of PSHA and SPSHA are compared, considering the spectral and return periods that are of typical interest for earthquake engineering. Finally, a comparison with the SPSHA map based on a well- established source model for Italy is also provided.