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The most distinctive features of sound insulation structures are their flexibility and porosity. Therefore, the flexible epoxy matrix material was made cellular using a suitable foaming agent. In addition, hollow glass microspheres (HGMs) were added to the epoxy matrix. Thus, the sound wave refraction was increased by obtaining cavities in the cell walls. Structures with different densities and voids were created by changing the ratios of the filling material and foaming agents used in the sandwich. An aluminum (Al) honeycomb was used to protect the insulation materials\" structural integrity and ensure the homogeneous distribution of sound waves. The effect of density differences on sound insulation values was investigated. The mechanical properties of sandwich structures were determined using compression and three-point bending tests. The distribution of the filler in the matrix was visualized using SEM. TGA, DSC, thermal conductivity, dielectric, and flammability tests were also performed to determine their thermal, electrical, and flammability properties. During the formation of cells in the flexible epoxy, the HGMs were positioned in the cell wall by internal gas pressure. Low-density structures performed better at low frequencies, while high-density structures at high frequencies.

To facilitate the monitoring and management of modern transportation systems, monocular visual traffic surveillance systems have been widely adopted for speed measurement, accident detection, and accident prediction. Thanks to the recent innovations in computer vision and deep learning research, the performance of visual traffic surveillance systems has been significantly improved. However, despite this success, there is a lack of survey papers that systematically review these new methods. Therefore, we conduct a systematic review of relevant studies to fill this gap and provide guidance to future studies. This paper is structured along the visual information processing pipeline that includes object detection, object tracking, and camera calibration. Moreover, we also include important applications of visual traffic surveillance systems, such as speed measurement, behavior learning, accident detection and prediction. Finally, future research directions of visual traffic surveillance systems are outlined.

Food security has become a significant issue due to the growing human population. In this case, a significant role is played by agriculture. The essential foods are obtained mainly from plants. Plant diseases can, however, decrease both food production and its quality. Therefore, it is substantial to comprehend the dynamics of plant diseases as they can provide insightful information about the dispersal of plant diseases. In order to investigate the dynamics of plant disease and analyze the effects of strategies of disease control, a mathematical model can be applied. We show that this model provides the non-negative solutions that population dynamics requires. The model was investigated by using the Atangana-Baleanu in Caputo sense (ABC) operator which is symmetrical to the Caputo-Fabrizio (CF) operator with a different function. Whereas the ABC operator uses the generalized Mittag-Leffler function while the CF operator employs the exponential kernel. For the proposed model, we have displayed the local and global stability of a nonendemic and an endemic equilibrium, existence and uniqueness theorems. By applying the fractional Adams-Bashforth-Moulton method, we have implemented numerical solutions to illustrate the theoretical analysis.

In many applications, free surface flow through rigid porous media has to be modeled. Examples refer to coastal engineering applications as well as geotechnical or biomedical applications. Albeit the frequent applications, slight inconsistencies in the formulation of the governing equations can be found in the literature. The main goal of this paper is to identify these differences and provide a quantitative assessment of different approaches. Following a review of the different formulations, simulation results obtained from three alternative formulations are compared with experimental and numerical data. Results obtained by 2D and 3D test cases indicate that the predictive differences returned by the different formulations remain small for most applications, in particular for small porous Reynolds number ReP < 5000. Thus it seems justified to select a simplified formulation that supports an efficient algorithm and coding structure in a computational fluid dynamics environment. An estimated accuracy depending on the porous Reynolds number or the mean grain diameter is given for the simplified formulation.

We present a new 2.5D model for predicting the concentration of nitrogen dioxide (NO2) at street level in an urban area. This work develops the first prototype of a tool that should provide fast quantitative answers to help decision-making on the suitability of implementing traffic restrictions during air pollution episodes. The model first solves the wind flow over the city streets ignoring vorticity and turbulence. The obtained velocity field is used to transport the pollutant via a semi-Lagrangian model, combining the particle finite element method of second generation (PFEM2) with the finite element method. A variable absorption term is used to account for the part of the contaminant entering and leaving the calculation plane. The NO2 emissions are estimated from the historical traffic data. The model has been tested during four air pollution episodes in the city of Barcelona (Spain), two in summer and two in winter. A comparison against experimental measurements has been performed at seven different locations throughout the city with promising results.

Granular flow is common in many industrial applications, and involves heat generation from frictional contacts and inelastic collisions between particles. The self-heating process is still poorly understood despite being intrinsic to many processes. This work, for the first time, explores this problem experimentally by quantifying the temperature rise of granular flows in a rotating drum with a robust methodology based on infrared thermography. Particles of four different materials (lead, steel, plastic and glass) are used in the experiments, at various rotation speeds and drum fill ratios. To assess the mechanical behaviour, the flow regime of every experiment was determined. It was inferred that particles with higher density tend to generate more heat. It was also revealed that increasing the rotation speed favours the temperature rise. At the same time, the fill ratio had the least influence on the thermal response of the particulate systems considered. his project is funded through Marie SKŁODOWSKA-CURIE Innovative Training Network MATHEGRAM, the People Programme (Marie SKŁODOWSKA-CURIE Actions) of the European Union's Horizon 2020 Programme H2020 under REA grant agreement No. 813202. Dr. Franci acknowledges the support from MCIN/AEI/10.13039/501100011033 and FEDER Una manera de hacer Europa for funding his work via project PID2021-122676NB-I00. Prof. Oñate acknowledges the Severo Ochoa Programme through the Grant CEX2018-000797-S funded by MCIN/AEI/10.13039/501100011033.

We present a general framework for the analysis and modelling of frictional contact involving composite materials. The study has focused on composite materials formed by a matrix of rubber and synthetic or metallic fibres, which is the case of standard tires. We detail the numerical treatment of incompressibility at large deformations that rubber can experience, as well as the stiffening effect that properly oriented fibres will induce within the rubber. To solve the frictional contact between solids, a Dual Augmented Lagrangian Multiplier Method is used together with the Mortar method. This ensures a variationally consistent estimation of the contact forces. A modified Serial-Parallel Rule of Mixtures is employed to model the behaviour of composite materials. This is a simple and novel methodology that allows the blending of constitutive behaviours as diverse as rubber (very low stiffness and incompressible behaviour) and steel (high stiffness and compressible behaviour) taking into account the orientation of the fibres within the material. The locking due to the incompressibility constraint in the rubber material has been overcome by using Total Lagrangian mixed displacement-pressure elements. A collection of numerical examples is provided to show the accuracy and consistency of the methodology presented when solving frictional contact, incompressibility and composite materials under finite strains.

The suffusion susceptibility of the soil samples is evaluated through an erosion resistance index. Thanks to existing statistical analyses, the erosion resistance index is estimated from several soil parameters. In actual exploitation, the soil properties with the input parameters related to the grain distribution of the soil… vary greatly from the original design value due to the influence of many factors. One of the factors is the inherent variability. Inherent soil variability is modelled as a random field. The usual problems used to assess the suffusion susceptibility may be not give accurate results or fully evaluate the actual working ability of the ground in each case. This is one of the reasons why dams are still eroded when they are put into use. The paper aims predict erosion resistance index of the earth dam using two-dimensional (2D) Stochastics random field, modelling the initial problem, considering the variability spatial of soil properties, using the assumption of a Normal random field of soil characteristics parameters. The paper shows the predicted results of the variability spatial of erosion resistance index of Phu Vinh dam-Vietnam. Furthermore, the paper also represents the happened probability of suffusion susceptibility at the different zones in the earth dam body.

In this paper an enhanced version of the semi-explicit Particle Finite Element Method for incompressible flow problems is presented. This goal is achieved by improving the solution of the advective sub-problem that results of applying the Strang operator splitting to the Navier–Stokes equations. An acceleration term is taken into account in the solution of the advective step and the Stokes problem. The solution of the advetive step is perfomed using a SPH kernel. Two test cases are solved for validating the methodology and estimating its accuracy. The numerical results demonstrate that the proposed scheme improves the accuracy of the semi-explicit PFEM scheme.

The methodology previously proposed by the authors to solve particle-laden turbulent flows through a multiscale approach is extended by introducing a continuous function for thedispersed phaseconcentration. The proposed continuous model is especially useful for studying the motion of particle streams in which gravitational and inertial effects cause the particles to deviate from a simple trajectory following the surrounding flow, as would be the case for the limit of very small, massless particles. The results show an excellent comparison between the solutions obtained using the continuous model and simulations evaluating the forces on each particle individually. Distinct advantages of the continuous approach are a much lower computational overhead, a better load balance and ease ofparallelization. The multiscale methodology proposed may be used in the area ofmodeling and simulationof airborne infectious diseases.

This study investigates a retailer's ordering strategy under the framework of the economic order quantity (EOQ) model. A supplier offers a retailer a disposable coupon and allows it to place a special order at any time in a promotion period. The promotion period is not necessary short and shortages are allowed throughout the time horizon. In addition to the special order time and the special order quantity, the retailer needs to decide whether to place some regular orders in the promotion period before placing the special order for the purpose of making better use of this coupon. We show that the coupon should be used to the retailer's first order in the promotion period regardless of the duration of the promotion period. Moreover, the retailer's maximum inventory level is higher than that in the classical EOQ model. We find that a longer promotion period can benefit the retailer by endowing it with more flexibility in its decision-making. Therefore, the supplier can improve the cash flow and reduce the overstock by integrating a disposable coupon with a longer promotion period. Numerous managerial insights are obtained from sensitivity analysis and numerical experiments.

At present, the beam-column connection system through a self-centering post-tensioned connection is currently an alternative to improve the seismic behavior in reinforced concrete buildings; by allowing its elements to have a linear behavior (no damage) in the face of displacements produced by seismic actions. This paper deals with the numerical modeling of the seismic behavior for a self-centering connection based on the Discrete Element Method (MED) is presented, with the aim of validating the hysterical response of the numerical model with an experimental test of the literature. The results demonstrated the horizontal distortions in the column, which are the product of the numerical simulation of the model subjected to a load that increases over time with 4 different stiffness coefficients. In addition, the hysteretic graph is presented as a result of the numerical simulation of the model, with an adequate stiffness coefficient and normal damping, subject to a cyclic load that is reversed as a function of time. The movement of the connection is controlled by the horizontal distortions of the column, achieving an approximate reproduction of the hysterical behavior expected in this type of connection. With the results shown, a simple bilinear hysteresis law is proposed, which allows its simplified use for its application in the modeling of reinforced concrete buildings with self-centering connections.

In this paper, a computationally efficient strategy for the approximation of the non-linear behaviour of structures through the finite element method is proposed. This proposal is based on the execution of a set of linear analyses in which the strength of the elements where the damage occurs is sequentially degraded and, in addition, complemented with a stabilized reduced numerical integration scheme for solid finite elements. Thus, the stiffness matrix only contains information of one integration point and, consequently, the stresses are computed only at that point. Also, due to the stabilization, it is possible to use reduced integration not only in the elements where the damage is assumed to occur, but in all the elements, guaranteeing a greater reduction in the computational cost. In this paper, the strategy of sequentially linear analysis with stabilized reduced integration is applied to several validation as well as application examples in which the quality of the approximation and the computational efficiency achieved are discussed. Finally, some future developments for the strategy are proposed.

To obtain an optimum power market the deregulation process is implemented for the entire electrical market and further classified as transmission and distribution units. Each firm focuses on delivering its best output which leads to congestion issues on transmission lines as there is in-adequate transmission capability to satisfy the load demand, and transmission congestion occurs. Transmission cable congestion results from a lack of coordination between the utilities that handle generating, transmission, and distribution leading to a generator failure, an abrupt increase in load demand, or the miscarriage of equipment, all of which can be fixed by FACTS devices. In this work, transmission line congestion is reduced using FACTS devices like UPFC and IPFC. The primary goal is to determine where FACTS devices should be placed. The main goal is to use the ANTLION optimization algorithm to locate the optimal position and size for FACTS devices. In an IEEE-14 bus system, UPFC and IPFC are individually connected and parameters are analyzed and formulated for better transmission among energy sectors.

'''– Design of steep slopes and retaining walls, reinforced with geotextile or geogrids, requires internal stability checks usually referred to a critical failure surface, which determines the amount of reinforcement required. In determining the length of the reinforcement layers the position of the critical surface and also of the sub-critical surfaces must be considered. In relation to these, are verified the anchorage lengths required to ensure the pullout resistance of the reinforcements. This paper presents a study based on limit equilibrium analysis, with bi-linear failure surface, to determine the amount and length of the reinforcement layers required. The model allows replacing Jewell charts by algebraic equations and iterative calculation processes. The results obtained for the minimum length of reinforcements agree with good accuracy for effective friction angles greater than or equal to 30° and indicate that shorter lengths can be used for materials with lower effective friction angle. Expressions for the calculation of the anchorage length are also presented for the three possible cases: anchorage in a section under the projection, part under the projection and beyond the horizontal projection of the slope face. '''Palavras Chave –''' talude, solo reforçado, geotêxtil, geogrelha, superfície sub-crítica, comprimento de reforço. '''Key words''' – slope, reinforced soil, geotextil, sub-critical surface, reinforcement length. *Professor Associado, D.Sc. UTFPR - Universidade Tecnológica Federal do Paraná, Curitiba, Paraná, Brasil. E-mail: [mailto:rfkpuppi@utfpr.edu.br rfkpuppi@utfpr.edu.br] / [mailto:rfkpuppi@gmail.com rfkpuppi@gmail.com] **Professor EBTT, M.Sc. UTFPR - Universidade Tecnológica Federal do Paraná, Curitiba, Paraná, Brasil. E-mail: [mailto:caron@utfpr.edu.br caron@utfpr.edu.br]

In this paper, an analytical solution is developed to investigate soil consolidation around a pile under earthquake loading. The solution is validated using finite element method. The influence of various parameters on excess pore water pressure is analyzed. The results show that excess pore water pressure increases with depth and is positively correlated with n and Neq/N1, while negatively correlated with η, χ, kv, and td. The values of η, χ, kv, Neq/N1, and td affect excess pore water pressure during and after the earthquake, while the value of n only affects excess pore water pressure after the earthquake. The growth rate of excess pore water pressure during the earthquake is positively correlated with n, η, kv, and Neq/N1, and negatively correlated with χ and td. The dissipation rate of excess pore water pressure during the earthquake is positively correlated with η, χ, kv, Neq/N1, and td, and negatively correlated with n. Additionally, a formula for calculating the reconsolidation settlement of pile-soil foundation after an earthquake is proposed, and the effects of pile and soil parameters on pile-soil foundation reconsolidation settlement are analyzed. The results indicate that reconsolidation settlement can be divided into two stages: rapid settlement stage and slow settlement stage. The total settlement of the foundation is positively correlated with n, η, and Neq/N1, while negatively correlated with χ, kv, and td.

The use of steel poles as support structures for lines in Mexico has increased in the last 30 years, mainly due to the increase in urban and suburban sprawl that demand less right of way for this type of infrastructure and less space for their foundations. To fulfill these requirements, numerous studies have been carried out related to dielectric sizing, optimization of the distance between phases to reduce electrical losses, wind hazard associated with the cable-insulator-hardware-structure-foundation system, structural design criteria based on reliability, natural-scale mechanical tests, among others. This article presents some reflections related to the different stages of the design of metal poles for transmission lines, from input data to structural designs, following the criteria of the Mexican electrical industry for a 230 kV pole, 2 circuits, located in Mexicali, B.C.

This article evaluates how the seismic pressures developed in embedded walls are affected by different wall stiffness and various contact soil-wall conditions. Several two-dimensional numerical models of an embedded wall-soil system were developed in Abaqus® by varying the wall stiffness. One model considered the wall as very rigid with a large modulus of elasticity and the other one considered the wall as flexible with original modulus of elasticity. Wall heights of 10, 20 and 30 meters were considered on the models to obtain different wall stiffness. The contact between the soil and the wall is modified by changing the friction coefficient between 0 to 0.75. The response of the soil is validated using 1D nonlinear site response analyses. The analyses are performed using records that match a narrow-band modified target spectrum for a moment magnitude of 7.70. The results show that the rigid walls developed larger seismic pressures than the flexible walls when subjected to the same earthquake records. The seismic soil pressures in the rigid walls do not change considerably by varying the contact condition between the soil and wall. Changes in the friction coefficient have a major impact on the seismic pressure distributions on flexible walls.

The Puerto Rico Soil Engineering Office (OIS) was founded in 1975 and is currently under the Design Area of ​​the Highway and Transportation Authority (ACT). In its foundation, the SEO was composed of a Soils Engineering Division and a Geology Division. Its main function was the subsoil exploration for the geotechnical structures designed and constructed by the PRHTA. Over time, the functions of the SEO evolved while soil engineering and rock engineering were evolving. Today, the SEO continues to attend to inquiries during projects’ design and construction phases. Additionally, the SEO attends several geotechnical initiatives like Geotechnical Asset Management and Unstable Slope Management. This article presents the contributions and innovations in the practice of geotechnical engineering that the OIS has attended and has had a leading role with emphasis on new analyzes and equipment that meet state and federal requirements and current codes that have potential to be implemented in geographic areas in the Caribbean and Latin America with similar geotechnical and geological characteristics.

Nature-based Solutions (NbS) are imperative now, in view of the resulting effects of climate change and man-made alterations in coastal areas. The perspective to address coastal solutions may not be possible to be limited exclusively to ecological solutions. This article, based on a literature review, focuses on hybrid solutions for coastal erosion control. The review highlights examples from around the World that can be applied to islands, having Puerto Rico (PR) as a typical scenario. It presents a summary of how gray infrastructure commonly applied in the past decades can be re-designed and adapted to integrate natural solutions. This article provides significant facts about the merits of structural, ecological, and economical aspects that should be considered on NbS projects. This article helps understand the state of practice and possible solutions that can be implemented, especially, in tropical and sub-tropical regions.

Elbows are components in piping systems whose primary function is to achieve a change in flow direction. Their study is relevant, since they present higher stress levels than those observed in straight sections. Early investigations determined that this effect is caused by the ovalization effect and the presence of external moments. The capacity of a cross section to ovalize when external loads are applied results in increased flexibility of the elbows by decreasing the moment of inertia compared to a straight pipe. In this work, stress levels in elbows caused by external moments and internal pressure are studied. As a case study, a series of elbows of various diameters and thicknesses with suitable characteristics for understanding the phenomenon of ovalization and the comparison of different calculation methodologies is proposed. The stresses obtained by applying the ASME B31.1 and ASME B31.3 codes are compared with those obtained by a numerical model of finite elements, through a novel indicator called the Normative Safety Margin. This indicator considers the admissible stresses established by the specifications for the materials of the accessories. Applying B31.1 Code, higher normative safety margins are obtained than those obtained with B31.3. For the entire series under study and all types of applied loads, lower normative safety margins were obtained when the accessories are more flexible.

The increase in crash-related pedestrian fatalities, primarily in urban streets, has promoted the development of technological innovations to mitigate this global problem. This article presents the results of an experiment that used virtual reality technology to study the performance of pedestrians at mid-block crossings of urban streets and the impact of a Road Information Assistance System [RIAS]. The RIAS was simulated as a handheld device that displays warning symbols or a combination of symbols and real-time information about the vehicles approaching the crosswalk to assist pedestrians in making the crossing decision. The experiment simulated a connected urban environment that can receive and transmit data from sensors in the infrastructure, vehicles, and pedestrians [via the RIAS]. The study evaluated the walking speeds, the vehicle gaps selected to cross the street, and the number of successful crossing events with no collisions. Three groups of twelve subjects [no RIAS, simple RIAS, and complex RIAS] were selected. The age and gender of the subjects, as well as the RIAS type used to cross the street, had significant effects on the average walking speed. The distributions of the average gap accepted by each of the three groups, based on the RIAS type, were statistically different. The group that used the RIAS device displaying symbols only had the worst performance and the highest average gap accepted when crossing the street.

This paper provides experimental data on the temperature rise during granular flows in a small-scale rotating drum due to heat generation. All heat is believed to be generated by conversion of some mechanical energy, through mechanisms such as friction and collisions between particles and between particles and walls. Particles of different material types were used, while multiple rotation speeds were considered, and the drum was filled with different amounts of particles. The temperature of the granular materials inside the rotating drum was monitored using a thermal camera. The temperature increases at specific times of each experiment are presented in form of tables, along with the average and standard deviation of the repetitions of each setup configuration. The data can be used as a reference to set the operating conditions of rotating drums, in addition to calibrating numerical models and validating computer simulations. This project is funded through Marie SKŁODOWSKA-CURIE Innovative Training Network MATHEGRAM1, the People Programme (Marie SKŁODOWSKA-CURIE Actions) of the European Union's Horizon 2020 Programme H2020 under REA grant agreement No. 813202. Dr. Franci acknowledges the support from MCIN/AEI/10.13039/501100011033 and FEDER Una manera de hacer Europa for funding his work via project PID2021-122676NB-I00. Prof. Oñate acknowledges the Severo Ochoa Programme through the Grant CEX2018-000797-S funded by MCIN/AEI/10.13039/501100011033.

The main objective of this research is to formulate and couple technologies for modeling discrete and continuous media using real particle morphologies. To that end, two coupled formulations based on virtual modeling technologies of single real particles with another one called real particle packing technique are presented. The first formulation employs Fourier descriptors’ theory to virtually achieve the morphology and construct a repository of real particle geometries. The second formulation is a particle packing method, supported by advancing front techniques combined with dynamic methods. This method presents a stochastic formulation and allows the packing of particle systems following continuous, discrete and empirical statistical distributions. The coupling of both techniques is a very efficient tool to achieve discrete or continuous media geometries to solve engineering problems. Three different examples are developed to illustrate the usefulness of the formulations. The first one is a discrete angle-of-repose problem involving clusters of spheres (real particle morphologies are described with groups of spheres); in the second example the same angle-of-repose problem is resolved with real particles. In the third case, which involves continuous medium mechanics, a small-scale road engineering problem is modeled, specifically, the testing of an asphalt concrete.

At present, the researches on the mechanical properties of sand aggregate mainly focus on the shaping process of particles, and lack the researches on the crushing mechanism. This paper first defines the shaping process of stone powder wall, and explores the crushing mechanism of sand aggregate by adopting multiple times of small energy crushing. The effect of energy is investigated by simulation and experiment. The machine-made sand crushing mechanism is analyzed by establishing corresponding contact mathematical models. The result shows that the stone powder wall involves two mathematical models under impact: the elastic-plastic model at low impact velocity and the elastic-brittle model at high impact velocity. '''Key words:''' machine-made sand; stone powder wall; crushing mechanism; mechanical contact model

The value of the gas-path parameter, exhaust gas temperature margin (EGTM), is the critical index for predicting aeroengine performance degradation. Accurate predictions help to improve engine maintenance, replacement schedules, and flight safety. The outside air temperature (OAT), altitude of the airport, the number of flight cycles, and water washing information were chosen as the sample input variables for the data-driven prognostic model for predicting the take-off EGTM of the on-wing engine. An attention-based deep learning framework was proposed for the aeroengine performance prediction model. Specifically, the multiscale convolutional neural network (CNN) structure is designed to initially learn sequential features from raw input data. Subsequently, the long short-term memory (LSTM) structure is employed to further extract the features processed by the multiscale CNN structure. Furthermore, the proposed attention mechanism is adopted to learn the influence of features and time steps, assigning different weights according to their importance. The actual operation data of the aeroengine are used to conduct experiments, where the experimental results verify the effectiveness of our proposed method in EGTM prediction.

The bearing was a key component of the mining machine tire unloader machine and was subjected to random multiaxial stress during operation. Therefore, the life prediction of bearing was of safety guidance. In this paper, a bearing life prediction method based on the critical plane method under multiaxial random loading was proposed. Firstly, a virtual prototype model was built based on the actual working conditions of the tire unloader machine to obtain the time load history of the bearing. Transient dynamic analysis of the bearing was carried out to obtain the triaxial stress-strain time histories at the hazardous locations of the bearing. A new coordinate system was established using the hazard node as the coordinate origin, and the location of the critical plane was searched for based on the critical plane multiaxial fatigue theory, combined with the maximum shear strain amplitude on the critical plane for multi-axial rain flow cycle counting to obtain the damage amount in each direction. At the same time, the life calculated from the maximum damage amount was used as the final life, resulting in a cycle count of the bearing of 268,303 cycles and a duration of 1490.58h. The results of this study could be used as a guide to predict the service life of the bearing in large machinery subjected to multiaxial random stress conditions.

In order to reduce the number of hydraulic decoders and hydraulic control pipelines in hydraulically controlled intelligent wells, reduce production costs and improve oil recovery efficiency, the structural design of ICV control of two hydraulic control pipelines and a single hydraulic decoder for four production layers in the well was completed. By simulating the response law of downhole hydraulic signals and the stress analysis of each structure, the motion equation of the layer selection structure of the hydraulic decoder was established with 4 MPa as the unlocking pressure, and ADAMS was used to complete the dynamic simulation analysis. The variation results of displacement, angle, velocity and acceleration in the process of motion were obtained. Finally, the prototype of the hydraulic decoder was processed by stereo photo curing 3D printing equipment. Two hydraulic pumps were used to press alternately, and the selection of four layers of the hydraulic decoder was realized through two hydraulic control pipelines. The self-locking structure could realize the established function, and there was no interference and stuck between the components, which verifies the effectiveness of the design.

This paper is motivated by the renewed interest in space exploration and the need to provide structurally sound and resource-efficient shielding solutions for valuable assets and future habitable modules. We present, implement and test a methodology for the preliminary design and assessment of optimal arch forms subjected to self-weight as well as seismically induced loads. The numerical framework, built around a limit thrust-line analysis, previously published by the authors, is summarized first. This is followed by a detailed account of the form-finding algorithm for arches of variable thickness. Special attention is placed on the physical feasibility of our assumptions and the justification of the engineering inputs adopted. The newly form-found arches achieve material efficiencies between 10% and 50% in comparison with their constant minimum-thickness circular or elliptical counterparts, depending on the relative intensity of the seismic action. The influence of the initial input geometry and the stabilising presence of additional shielding material against extreme radiation are also evaluated with emphasis on the effects of low-gravity conditions. Finally, a case study is presented and Discrete Element Models of constant and varying thickness arches (VTAs) are assessed under a set of representative ground-motions on a lunar setting. The significant over-conservatism of constant thickness arches (CTAs) is made manifest and potential improvements of the optimally found arch shape are highlighted. Although developed with extraterrestrial applications in mind, the results and methods we present herein are also applicable to terrestrial conditions when material efficiency is of utmost concern.

Slope stability is one of the most common problems in construction design. The application of application software often follows a pattern, using only fixed input parameters and resulting in a factor of safety according to the parameters themselves. This calculation model is only correct during the time when the shear resistance parameter (c, j) of the ground does not change. Therefore, this method is no longer appropriate once utilizing the structure because of leading to slope instability and causing landslides that damage to the slope after a period of exploitation. The experimental studies have shown that the shear resistance parameter (c, j) of the soil ground changes randomly with depth. As a result, current mechanical computational models are no longer valid. This paper proposes a new model to analyze stability based on reliability theory with the change of shear resistance parameters by depth. Firstly, by using Karhunen – Loeve series, the result of slope stability coefficient of the proposed model is smaller than those without consideration of shear resistance variation (c, j) by depth. Then, by using Monte - Carlo simulations (n=1000) combined with Karhunen – Loeve series, the results obtained are different from those which only consider the static problem, so the problem of random quantities and the probability of failure increase significantly.

The impact force of debris flow is not only an important indicator of the risk assessment of debris flow and the strength impact resistance of buildings against debris flow, but also an important parameter in the design of various debris flow prevention projects (such as the check dam and the drainage channel, etc.). The pressure sensors are arranged at different positions (monitoring points) on the upstream face of the check dam. By changing the slope of the drainage channel, the bulk density of debris flow and the slope gradient of the upstream face of the check dam, the time history curves of the impact force at the monitoring points under different experiment conditions are obtained. The characteristic value of impact force of debris flow acting on the surface of sand retaining dam is analyzed, and the evolution law of mean value and maximum value of impact force of debris flow at the same detection location with the above conditions is obtained. The mean value and maximum value of debris flow impact force at dif-ferent detection locations under the same working condition are analyzed to obtain the evolu-tion law of debris flow impact force at different locations, and then the distribution trend of debris flow impact force on the upstream face of the check dam is obtained. The research results provide scientific and reasonable theoretical basis and technical support for the stability analysis of the check dam, so as to better serve the disaster prevention and reduction of debris flow, which will improve the technical level of the debris flow prevention project to a certain extent.

This paper presents an experimental and numerical investigation on the mechanisms of damage onset and evolution in unidirectional carbon fibre reinforced thermoplastic (CFRTP) composites subjected to off-axis compressive loadings. A test fixture was designed to prevent buckling, splitting and end collapsing of specimens during test. A series of compression tests were conducted with specimens of various off-axis angles. Different failure mechanisms and nonlinear stress-strain responses were observed and studied. The fracture angles of the tested specimens were evaluated and analysed according to Puck’s theory. The off-axis compression failure envelope based on LaRC05 and Hashin criteria was presented using finite element analysis and compared to experimental results. It is shown that the LaRC05 criterion can provide accurate predictions for matrix cracking failure mode of unidirectional thermoplastic composites controlled by compression-shear combined stresses.

El cálculo de variaciones es una herramienta matem´atica muy importante que ,en algunos casos,se emplea para resolver problemas en la naturaleza de contenido práctico e incluso teórico.Es por ello que presentamos algunos ejemplos sencillos resueltos completamente con la llamada teoría de Jacobi de los puntos conjugados

The objective of this work is to carry out numerical analyzes of solid elements related to structural carbon steel, both for medium strength steel (MS250) and for high strength steel (HS350); stainless steel 304 (SS) and the inconel 718 superalloy (SI). For this, a mathematical formulation based on the Finite Element Method (FEM) was computationally implemented, which used the FORTRAN programming language, whose purpose was to obtain the values ​​of stresses, deformations and nodal displacements of the steels and the alloy, taking into account that the materials present elastic-linear behavior. As for the stress analyses, the von Mises rupture criterion method was used. For the discretization of solid elements, 4-node tetrahedral (T4), 8-node hexahedral (H8) and 20-node hexahedral (H20) finite elements were used, with each node having three degrees of freedom. The Gauss-Legendre method (Gauss quadrature) was also used for the numerical resolution of the integrals. In order to verify and validate the responses obtained from the implemented computational program, comparisons were made with results found in the literature, and then numerical analyzes of the materials were carried out. This work intends to efficiently contribute to the calculation of stresses, strains and displacements in solids.

For improving the energy efficiency of hopping robot, an asymmetric spring loaded inverted pendulum hopping model with leg mass is considered. The period orbit problem of two-legged hopping robot is investigated. Firstly, the hybrid dynamic model is constructed. Then the passive hopping gaits are found using quasi-newton optimization method. Secondly, a PD controller is implemented to track the desired pitch trajectory of the body. Through applying control during stance phase, period orbits of the robot with offset body mass is obtained. Finally, the effect of the location of the leg mass and the body mass on hopping performances is investigated.

The development of high-speed train lines has increased during the last twenty years, leading to more demanding loads in railway infrastructures. For these reasons, a discrete element model of granular material was carried out using 3D spherical particles with a rolling resistance, in order to consider non-sphericity of ballast stones. Other discrete element model representing granular materials as sphere aggregates (sphere clusters) has been also implemented. Current work presents the methodology followed to develop the discrete element model able to calculate railway ballast interaction. Interaction between discrete and finite elements is another key point of the calculations that is addressed. This document displays some results evaluating the influence of material parameters and geometric representation in the simulation of railway ballast and presents some laboratory tests calculated with the numerical application developed. &nbsp

Up to 30% of all drinking water is wasted due to leaks in water distribution networks (WDNs). In times of drought and water shortage, wasting so much drinking water has a considerable environmental and financial cost. In this paper, we present a microservice architecture for leak localization in WDNs, where heterogeneous sources of data consisting of sensor measurements, Geographic Information System (GIS), and Customer Relationship Management (CRM) data are used to feed a leak monitoring solution which combines hybrid data-driven and model-based leak detection and localization methodologies. The solution is validated using in-field leak experiments in an operational WDN. The final leak probabilities are presented in a visualization dashboard. The search zone for most leaks is reduced to a few kilometers or less. For other leaks, the solution is able to indicate a larger search zone to reflect its higher leak prediction uncertainty.

Thestudyonthe assembly support for the large cantilevered cover beamwascarried outby conducting real-time monitoringon the assembly frames’ strain and displacement developmentprocesses in the actual project. Modeling of the support and numerical simulation for actual working conditionswere presented. The monitoring data and analysis results show that the overallstress ratioof the supportwasless than 30%.And asthe concrete structure being supported hardened, the support framewasunloaded. When the stress ratio was thenreduced to less than 10%, it was the most appropriate time to remove the bracing frame. The maximum strainfrom the simulationdidnot exceed 66.26% of the theoretical maximum strain of the rod. The actual construction conditions and the spatial form of the supportaffectedthe force situation, resulting in thedeviation from the theoretical maximum strainat certain phases. The analysis results and trends reflect the low utilisationrate of such framingrods. The results of the study can be used as a reference for the topology optimisation of assembled supportframes for large cantilevered cover beams.

ispartof: JOURNAL OF BRIDGE ENGINEERING vol:28 issue:1 status: accepted

Thunderstorm is a severe phenomenon which can produce downburst winds capable for causing significant damage or even the collapse of low-rise structures. Experimental tests and numerical simulations are widely used by the Wind Engineering (WE) community for gaining increased understanding of complex winds like downbursts. In this paper, the accuracy of the Unsteady Reynolds-averaged Navier-Stokes (URANS) and Scale-Adaptive Simulation (SAS) to reproduce a vertical downburst wind - previously tested in the WindEEE Dome wind-simulator facility - was investigated. CFD results were first validated with the experiments and then used to study the dynamics of the phenomenon. The most suitable CFD setting (i.e. SAS case based on the k-ω SST turbulence model) was able to reproduce the development of the primary vortex ring, shedding of secondary rings induced by Kelvin-Helmholtz (KH) instabilities and the periodic detachments of smaller secondary vortices ahead the primary vortex. The superposition of these three contributions has shown to determine the temporal variation of the characteristic nose-shaped vertical profile which was found in the experiments. The performed simulations were also compared to field measurements from the NIMROD project showing a high level of agreement.

'' This work aims to develop a computational tool for synthesizing a four-bar linkage mechanism that can generate a prescribed path for a point coupler link to follow. The dimensional synthesis of the mechanism involves determining the lengths of each of its links. In this case, two possible configurations are evaluated: crank-rocker and/or double crank. The prescribed path consists of an arbitrary number of points contained in a plane, along with the corresponding rotation degrees of the driver element.'' Dimensioning the mechanism involves many variables, and it is possible to obtain various configurations that generate paths that are approximately the desired path. Therefore, the synthesis problem arises as an optimization problem in which the objective function seeks to minimize the Euclidean norm between the prescribed points and the points earned. To solve the optimization problem, a user-friendly computer program called SIDIGETRA was developed using the genetic algorithms numerical technique. Design constraints were imposed to obtain an open configuration of the mechanism and to avoid branching defects, order, and Grashof. The program's proper functioning was validated by comparing the results obtained in case studies published in a research article in which the genetic algorithms technique was also applied. The percentage relative errors between the coordinates of the obtained points and prescribed points were calculated and found to be satisfactory. Additionally, the results generated by SIDIGETRA were validated with a visual comparison between the prescribed trajectory and the one obtained by simulating the position analysis of the synthesized mechanism using a commercial software tool designed for this purpose.

Bearing is an important rotating support part of tyre unloader, and its fatigue reliability is an important part of the whole system reliability. Because of the huge alternating stress, the support bearing is required to have high fatigue life and reliability. In this paper, combined with stress-strength interference model and statistical theory, the life distribution of bearing steel material is predicted by using group test data; Based on the multi-rigid body dynamics and finite element numerical simulation platform, the reliability of the bearing of tyre unloader under different operating years was predicted by using the different dimensional interference model. The results show that the maximum resultant force of the bearing at the bottom rocker arm of the tyre unloader can reach 150kN, and the maximum transverse and longitudinal forces can reach 108kN and 78kN. When bearing the weight of the whole tyre and turning, the inertia force is the largest, the maximum stress value is 1316.2MPa, which occurs in the bearing inner ring and ball contact part. After the statistics, the stress amplitude distribution of the bearing conforms to Weibull distribution, and the life of the bearing follows lognormal distribution. After 105 tyre unloading, the fatigue reliability of the bearing is lower than 0.82, which is consistent with the actual working condition. Therefore, this model can be used to calculate the fatigue reliability of bearings conveniently and quickly, and provide certain theoretical support for the safety and fatigue reliability prediction of bearings.

In order to solve the problem of "gas explosion" at the end of common rubber cylinder in the process of high temperature, high pressure and gas drive operation, the rubber cylinder with new structure suitable for 51/2 in casing pipe is developed. The "M" type single rubber cylinder structure is adopted in the new structure rubber cylinder, and the "gas explosion" problem of the end gas in the low-pressure side is solved by setting the double-layer staggered slotted steel cover to prevent outburst. The finite element method is used to simulate the setting of the rubber cylinder, and the structural parameters of the new rubber cylinder are obtained by single factor analysis and orthogonal optimization, simulation test and seal test were carried out to verify the sealing performance of the rubber cylinder. According to the actual working condition, the simulation test results and seal test results show that the sealing capacity of the packer reaches 50 MPa under the temperature resistance of 120℃, and the end steel cover is fully opened to wrap the rubber cylinder, which meets the operation requirements of high temperature and high pressure gas injection packer.