This paper presents the numerical calculation for the elastohydrodynamic journal bearing with ultra-small clearances (with the eccentricity ratios approaching unity), where in a local small area only the physically adsorbed layer is present, while in the other areas the sandwich film is present. It is shown that both the adsorbed layer and the elastic deformation of the surface strongly influence the performance of the bearing. For a given operating condition, the surface elastic deformation causes significant reductions in both the maximum hydrodynamic pressure and the load of the bearing, while it significantly increases the minimum clearance (for a given eccentricity ratio) and the friction coefficient. The surface elastic deformation also increases film stiffness. These effects are strongly dependent on the fluid-surface interaction; the stronger the fluid-surface interaction, the more significant the effect of the surface elastic deformation. The present study shows the considerable benefit of the adsorbed layer formed by the strong fluid-surface interaction in increasing the bearing minimum clearance (for a given load or a given eccentricity ratio) and reducing the friction coefficient of the bearing when the surface elastic deformation is involved.

Analytical modelling is an important part of distributed wireless MAC protocol research and analysis.Most of the protocols proposed in the literature are based on a countdown and use one of two different countdown types: DCF or EDCA type, both defined in the IEEE 802.11 group of standards.The difference between the two countdowns is seemingly negligible, but can lead to remarkable differences in network performance.In this paper, a new model of a simple protocol is developed that uses an EDCA type of countdown and employs a constrained priority freezing mechanism.It is based on a three-dimensional Markov chain that represents the operation of a single observed station.The model is validated by comparing the numerical results with the simulation results and shows a very high degree of accuracy.Therefore, the proposed model should serve as a basis for the development of more complex models of protocols using EDCA countdown with constrained priority freezing.

This study concerns digital tools and simulation methods necessary for the description, conception, perception, and analysis of spatial architectural and urban design.The purpose of the study is to categorize, analyse, and describe the influence of digital simulation tools and methods in architectural and urban design.The study analyses techniques, applications, and research in the field of digital simulations of architectural/urban ensembles while also referring to the benefits of their use both at the level of scientific and spatial perception of architectural/urban design.

This research aims to determine the static response of an arch dam before undertaking a dynamic analysis of the dam due to hydrodynamic and seismic stresses. An arch dam with soil interaction, a dam without soil contact, and a dam between soil and reservoir system were all modelled using ANSYS finite element software. The research intends to determine various deformations and stresses caused by the loads attributed to arch dams in different dam systems. Many different outcomes are mapped out and discussed, mainly as weight differences.

Estimation of vehicle dynamics, tire wear, and road profile are indispensable prefaces in the development of automobile manufacturing due to the growing demands for vehicle safety, stability, and intelligent control, economic and environmental protection. Thus, vehicle state estimation approaches have captured the great interest of researchers because of the intricacy of vehicle dynamics and stability control systems. Over the last few decades, great enhancement has been accomplished in the theory and experiments for the development of these estimation states. This article provides a comprehensive review of recent advances in vehicle dynamics, tire wear, and road profile estimations. Most relevant and significant models have been reviewed in relation to the vehicle dynamics, roll angle, tire wear, and road profile states. Finally, some suggestions have been pointed out for enhancing the performance of the vehicle dynamics models.

With the increase in demand for oil and oil products, the petroleum industry is faced with the requirement for more complex tools to increase production at lower prices. The complexity of drilling tools is manifested in the complex geometry, fabrication, assembly, deformations, stresses and loads acting on them. This study introduces a dual derrick simulation procedure in a marine environment which provides a step towards a better understanding by giving a simulation close to the real state. The derrick was considered in equilibrium, and then the derrick vibration was simulated using field data in order to obtain stress distribution. This implies that the derrick can move freely and cause deformations in all directions without constraints. In this paper, the finite element method was employed to simulate the derrick in a static state and in motion, and then the obtained stress distribution was compared for both cases. A literature review on the analysis of environment working conditions is provided. The results showed that the vibration of the platform increased the stress considerably. The maximum combined stress increased by 27 %, while the maximum bending stress increased by 40 % and reached considerably higher values in the beams connected to the top of the derrick.

This paper deals with the influence of the shading problem on the electrical production of a photovoltaic generator based on the analysis of the I-V and P-V characteristics of the PV generator for different operating scenarios.The shading problem not only causes energy losses but also increases the non-linearity of the I-V and P-V characteristics of photovoltaic systems.The choice of the model is an essential step to allow analysis and evaluation of the performance of photovoltaic generators.The single diode model was presented in the MATLAB / SIMULINK software.The study began with the presentation of the characteristics of a module, a comparison was made between the values of the obtained electrical parameters and those supplied by the manufacturer.To show the effect of shading on photovoltaic systems another comparative study was presented between a group of series-connected modules and another connected in parallel, both exposed to nonuniform partial shading.The obtained simulation results show that the influence of shading on a set of modules connected in series is greater than that of a set of modules connected in parallel under the same operating conditions.

Since the acoustic impedance in water cannot be neglected with respect to the mechanical impedance, the acoustic radiation caused by the vibration of structures in the compressible fluid would react to the structure. Therefore, the fluid-structure interaction needs to be considered. The finite element method is used for structure vibration analysis and the boundary element method for acoustic analysis. Sound absorption materials are used to reduce the scattering sound field in the reference region. The sensitivity analysis of a fully coupled structural-acoustic system is proposed. Numerical tests verify the correctness of the proposed algorithm.

Cloud and P2P computing allows the sharing of resources among its users from diverse geographical locations. The resources are heterogeneous in nature and possess distinct attributes. The majority of the existing techniques rely on the static attributes during resource selection. However, the matching of resources based on static attributes may not be the best for the execution of user jobs. The resources could be very attractive as per the static configuration but might be heavily loaded with other multiple jobs since the working memory and storage space might have already been utilized. Hence, there is a need to consider the dynamic state of the resources in order to locate the most suitable resources for user jobs. In this paper, a 2-phased multi-attribute decision making (MADM) mechanism is proposed to locate the appropriate resources. The first phase explains a mechanism to discover all the matched resources and the second phase then applies the PROMETHEE MADM approach on the set of resources to find the most suitable resource for the user job. The proposed approach enables users to find the most suitable resource for their respective jobs.

The integrity of the diesel generator set (genset) in the emergency power plant of a Nuclear Power Plant is considered.The genset consists of the diesel engine, the generator, and the common base frame on elastic spring-damper elements clamped to foundations.The genset is exposed to the seismic load, the short circuit impulse, and the synchronization failure load.The problem is solved via the finite element method (FEM).In the FE model, the diesel engine and the generator are represented with two lumped masses rigidly connected to the base frame with sets of massless bars.Strength criteria are specified according to the Russian Federal Codes and Standards in the Area of Atomic Energy Applications.The necessary number of spring-damper elements for preserving the integrity of the genset is determined.