The resistance performance and motion stability of deep sea remotely operated vehicles (ROVs) subjected to underwater motion conditions are studied on the basis of the unsteady Reynolds-averaged Navier-Stokes method combined with the six-degree-of-freedom equation of motion to quickly and accurately predict them. In the modeling process, we consider the complexity of ROV geometry and thus reduce the model to a series of regular geometries to maximize the position and weight of the original components. The grid and value slots of an ROV are divided, and the surface is reconstructed. The forward, backward, transverse, floating, and submerged resistance of ROVs are simulated and compared with existing experimental forces to determine the accuracy of the calculation method. Then, the oblique navigation of the ROV on the horizontal and vertical planes is studied. Furthermore, the motion response of the ROV to direct horizontal motion, heave, pitch, and yaw are studied. The force, moment, and motion time curves are obtained. The stability of ROV motion is analyzed to provide technical support for the safety of ROVs.
В статье исследуются проблемы автоматизации и интеллектуальной поддержки процесса математического и имитационного моделирования сложных объектов за счёт комбинации компонентно-ориентированного и онтологического подходов. В качестве основной прикладной области для применения обсуждаемых методов и средств предполагается использовать такое направление, как комплексное моделирование окружающей среды. В контексте изучаемых вопросов рассмотрены современные подходы к автоматизации компонентно-ориентированного моделирования. При интеграции компонентов-моделей в единую результирующую комплексную модель разработчику необходимо не только обеспечить формальное согласование со стандартами используемого каркаса моделирования, но и учитывать различные типы семантической и синтаксической неоднородности компонентов. В связи с этим выполнена классификация типов интеграции комплексных моделей, обсуждаются особенности реализации компонентно-ориентированного моделирования в авторской платформе создания систем, основанных на знаниях. В качестве иллюстративного примера рассматривается гидролого-экологическая балансовая модель.
The article considers the problems of automation and intellectual support of the mathematical and simulation modeling process of complex objects via a combination of component-based and ontological approaches. As the main application area for the discussed methods and tools, it is proposed to use the integrated environmental modeling domain. In this context, modern approaches to the automation of component-based modeling are considered. To couple model components into a final complex model, the developer needs not only to ensure formal agreement with the standards of the modeling framework but also to take into account various types of semantic and syntactic heterogeneity of components. In this regard, the classification of the integration types for complex modeling is carried out, the related implementation features in the author's platform for creating knowledge-based systems are discussed. The hydrological-ecological balance model is considered an illustrative example.
Aerospace-grade composite parts can be manufactured using Vacuum Bag Only prepregs through an accurate process design. Quality in the desired part can be realized by following process modeling, process optimization, and validation, which strongly depend on a primary and systematic material characterization methodology of the prepreg system and material constitutive behavior. The present study introduces a systematic characterization approach of a Vacuum Bag Only prepreg by covering the relevant material properties in an integrated manner with the process mechanisms of fluid flow, consolidation, and heat transfer. The characterization recipe is practiced under the categories of (i) resin system, (ii) fiber architecture, and (iii) thermal behavior. First, empirical models are successively developed for the cure-kinetics, glass transition temperature, and viscosity for the resin system. Then, the fiber architecture of the uncured prepreg system is identified with X-ray tomography to obtain the air permeability. Finally, the thermal characteristics of the prepreg and its constituents are experimentally characterized by adopting a novel specimen preparation technique for the specific heat capacity and thermal conductivity. Thus, this systematic approach is designed to provide the material data to process modeling with the motivation of a robust and integrated Vacuum Bag Only process design.
To model the risk of COVID-19 mortality in British care homes conditional on the community level risk.
A two stage modeling process (“doubly latent”) which includes a Besag York Mollie model (BYM) and a Log Gaussian Cox Process. The BYM is adopted so as to estimate the community level risks. These are incorporated in the Log Gaussian Cox Process to estimate the impact of these risks on that in care homes.
For an increase in the risk at the community level, the number of COVID-19 related deaths in the associated care home would be increased by exp (0.833), 2. This is based on a simulated dataset. In the context of COVID-19 related deaths, this study has illustrated the estimation of the risk to care homes in the presence of background community risk. This approach will be useful in facilitating the identification of the most vulnerable care homes and in predicting risk to new care homes.
The modeling of two latent processes have been shown to be successfully facilitated by the use of the BYM and Log Gaussian Cox Process Models. Community COVID-19 risks impact on that of the care homes embedded in these communities.
Problem and Aim. The article considers the problem of modeling such a pedagogical phenomenon as the cadet’s readiness for command activity. The military professional experience of the future officer was formalized and the correlation of “readiness” with the traditional competence of the military man was validated. The essential components of the modeling process of the cadet’s readiness for command activity are established, the criteria for the effectiveness of such modeling are determined. The purpose of the article is establish the essential components of the process of modeling the readiness of the cadet for command activity, determine the criteria for the effectiveness of such modeling. Methodology. Research methods: comparative analysis of military-vocational training technologies, highlighting the essential intentions of the cognitive plan in them, followed by designing a criteria base for the effectiveness of using such technologies in the formation of cadets’ readiness for command activities. The article considers the problem of modeling such a pedagogical phenomenon as the cadet’s readiness for command activity. The military professional experience of the future officer was formalized and the correlation of “readiness” with the traditional competence of the military man was validated. The essential components of the modeling process of the cadet’s readiness for command activity are established, the criteria for the effectiveness of such modeling are determined.
Recently, renewable energy (RE), such as solar energy, sources have proven their importance as an alternative source of fuel. The utilizing of solar energy can contribute to move the world towards relying on clean energy to curb global warming. However, the placement of solar farms is a major priority for planners as it is a critical factor in the succession energy project. This study combines one of the multi-criteria decision-making techniques Analytic Hierarchy Process (AHP) and Geographic Information System (GIS) to assess the suitability of land for establishing solar farms in Iraq. Numerous climatic, geomorphological, economic, and environmental criteria and some exclusionary constraints have been adopted in modeling process. It is supported by expert knowledge and a comprehensive literature review. The results showed that approximately 19% of the study area are optimal areas for installing solar farms. The southern, southeastern, and a few western regions obtained the largest part of the suitable lands. Furthermore, this approach can be adapted easily to cover different criteria and different weights in order to assist planners in deciding solar farm locations.
This paper extends the Wittrick-Williams (W-W) algorithm for hybrid dynamic stiffness (DS) models connecting any combinations of line and point nodes. The principal novelties lie in the development of both the DS formulation and the solution technique in a sufficiently systematic and general manner. The parent structure is considered to be in the form of two dimensional DS elements with line nodes, which can be connected to rigid/spring point supports/connections, rod/beam point supports/connections, and point connections to substructures. This is achieved by proposing a direct constrain method in a strong form which makes the modeling process straightforward. For the solution technique, the W-W algorithm is extended for all of the above hybrid DS models. No matrix inversion is needed in the proposed extension, making the algorithm numerically stable, especially for complex built-up structures. A mathematical proof is provided for the extended W-W algorithm. The proposed DS formulation and the extended W-W algorithm are validated by the FE results computed by ANSYS. This work significantly extends the application scope of the DS formulation and the W-W algorithm in a methodical and reliable manner, providing a powerful eigenvalue analysis tool for beam-plate built-up structures.
Non-equidistant GM(1,1) (abbreviated as NEGM) model is widely used in building settlement prediction because of its high accuracy and outstanding adaptability. To improve the building settlement prediction accuracy of the NEGM model, the fractional-order non-equidistant GM(1,1) model (abbreviated as FNEGM) is established in this study. In the modeling process of the FNEGM model, the fractional-order accumulated generating sequence is extended based on the first-order accumulated generating sequence, and the optimal parameters that increase the prediction precision of the model are obtained by using the whale optimization algorithm. The FNEGM model and the other two grey prediction models are applied to three cases, and five prediction performance indexes are used to evaluate the prediction precision of the three models. The results show that the FNEGM model is more suitable for predicting the settlement of buildings than the other two grey prediction models.
Abstract. Age-depth correlations are the key elements in paleoenvironmental studies to place proxy measurements into a temporal context. However, potential influencing factors of the available radiocarbon data and the associated modeling process can cause serious divergences of age-depth correlations from true chronologies, which is particularly challenging for paleolimnological studies in Arctic regions. This paper provides geoscientists with a tool-assisted approach to compare outputs from age-depth modeling systems and to strengthen the robustness of age-depth correlations. We primarily focused in the development on age determination data from a data collection of high latitude lake systems (50° N to 90° N, 62 sediment cores, and a total of 661 dating points). Our approach used five age-depth modeling systems (Bacon, Bchron, clam, hamstr, Undatable) that we linked through a multi-language Jupyter Notebook called LANDO (“Linked age and depth modeling”). Within LANDO we have implemented a pipeline from data integration to model comparison to allow users to investigate the outputs of the modeling systems. In this paper, we focused on highlighting three different case studies: comparing multiple modeling systems for one sediment core with a continuous, undisturbed succession of dating points (CS1 - “Undisturbed sequence”), for one sediment core with scattered dating points (CS2 - “Inconsistent sequence”), and for multiple sediment cores (CS3 - “Multiple cores”). For the first case study (CS1), we showed how we facilitate the output data from all modeling systems to create an ensemble age-depth model. In the special case of scattered dating points (CS2), we introduced an adapted method that uses independent proxy data to assess the performance of each modeling system in representing lithological changes. Based on this evaluation, we reproduced the characteristics of an existing age-depth model (Lake Ilirney, EN18208) without removing age determination data. For the multiple sediment core (CS3) we found that when considering the Pleistocene-Holocene transition, the main regime changes in sedimentation rates do not occur synchronously for all lakes. We linked this behavior to the uncertainty within the modeling process as well as the local variability of the sediment cores within the collection.