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Due to the growth of renewable energies, which requires cost reduction and efficiency in terms of structural health assessment, failure prevention, effective maintenance scheduling, and equipment lifespan optimization, in this paper, we propose an Ultra Wideband (UWB)-based accelerometer Sensor Node for low-power applications in offshore platforms. The proposed Sensor Node integrates a high-resolution accelerometer together with an Impulse Radio Ultra-Wideband (IR-UWB) transceiver. This approach enables effective remote monitoring of structural vibrations. This provides an easy-to-install, scalable, and flexible wireless solution without sacrificing robustness and low power consumption in marine environments. Additionally, due to the diverse and highly demanding applications of condition monitoring systems, we propose two modes of operation for the Sensor Node. It can be remotely configured to either transmit raw data for further analysis or process data at the edge. A hardware (HW) description of the proposed Sensor Node is provided. Moreover, we describe the power management strategies implemented in our system at the firmware (FW) level. We show detailed power consumption measurements, including power profiles and the battery-powered autonomy of the proposed Sensor Node. We compare data from a wired acquisition system and the proposed wireless Sensor Node in a laboratory environment.The wired sensor integrated into this acquisition system, fully characterized and tested, is our golden reference. Thus, we validate our proposal. Furthermore, this research work is within the scope of the SUREWAVE Project and is conducted in collaboration with the MARIN Institute, where wave basin tests are carried out to evaluate the behavior of a Floating Photovoltaic (FPV) system. These tests have provided a valuable opportunity to assess the effectiveness of the proposed Sensor Node for offshore platforms and to compare its performance with a wired system. [ABSTRACT FROM AUTHOR]

Riverine sampling of pollutants is commonly used to understand pollutants' transport pathways, relationships with hydrology, and overall presence in a waterbody. However, temporal gaps between sample collection introduce errors to these efforts, and guidance prescribing sampling frequency remains sparse. The magnitude of error often depends on a contaminant's transport mechanisms and local hydrologic conditions, making the creation of comprehensive sampling guidance difficult. This study analyzed a unique dataset that measured 18 analytes, including pesticides, nutrients, and pathogens, in three Iowa rivers for 90 consecutive days (May 4–August 1, 2000). This dataset provided a novel opportunity to relate pollutants to local hydrology and quantify errors associated with recurring sampling. Pesticide concentrations followed the spring flush phenomenon, where values were greatest during high streamflow in May and June but often depleted by July. Fecal coliform and total phosphorus (TP) also coincided with high flow, but unlike pesticides, their concentrations never diminished. Nitrate exhibited more complex behavior; concentrations were diluted during high flows and then increased as streamflow receded. Autocorrelations were significant for nitrate and atrazine in larger rivers but negligible for fecal coliform and TP. Loads were calculated for four pollutants with minimal non-detects (atrazine, fecal coliform, nitrate, and TP). We simulated intermittent sampling by selecting evenly spaced subsets of measured values to estimate loads, which were compared to the loads calculated using every daily sample to quantify error. This method typically overestimated nitrate loads but underestimated other pollutants, and errors often decreased in larger watersheds. Nitrate generally had the lowest error, while fecal coliform had the highest. We used these results to approximate the sampling frequency needed to bind errors within a certain threshold. [ABSTRACT FROM AUTHOR]

The importance of the buried pipelines lies in two main topics: the first is related to the very long length of these pipes, and therefore protecting them is expensive. The second topic is related to environmental pollution due to leaching, which is considered one of the main pollutants of groundwater. The research reviews the effects of geosynthetic reinforcement and its effect on buried pipelines subjected to different loading conditions to reduce the stresses on them and thus prevent leakage. The loads covered in this literature are the following: static load, dynamic load, permanent ground deformation, accidental damage, uplift pressure, explosion, lateral loading, and abrasive shear loading. The research focused on the use of synthetic ground reinforcements to protect these pipes. Available experimental and numerical investigations indicate the potential of using geosynthetics to reduce the effects of external loads on buried pipelines. The investigated studies proved that the protection of buried pipes with different types of geosynthetics is a successful method and decreased the stresses transformed to buried pipes. Most of the studies (45%) dealt with buried pipes subjected to static loading. The conventional geosynthetic material used in the protection of buried pipes is geogrid (38%). [ABSTRACT FROM AUTHOR]

The current state of calculation the result of the superposition of loads, or their effects, on a material body is analyzed. The limits of the current calculation methods, based on strength theories, in the case of technical structures are shown. The results of experimental research that refer, in general, to the superposition of two loads of the same nature and without addressing problems of loads of a different nature (mechanical, chemical, electrical, magnetic, radioactive etc.), in the case of technical structures and the environment is analyzed. Starting from the principle of critical energy, which is based on the concepts of the total specific energies’ participation of the loads and of the critical participation, general relations are deduced for these concepts, in the case of the nonlinear behavior of matter, as a function of power. These results are applied to the calculation of the superposition of loads of different nature on a technical structure, the environment and living organisms, taking into account the deterioration of matter. The influence of the loading speed (static, shock ...) is taken into account based on the value of the exponent in the behavior law, which was not possible in the previous calculation methods. From the analysis of the results obtained in the paper, it is found the utility and the high degree of generality of the principle of critical energy and of the concept of the specific energy participation.

Solar greenhouses have been widely used in the vast western and northern regions of China, due mainly to the convenient construction and installation, low economic cost, and outstanding environmental adaptability. The slender steel can be the load-bearing components of the section-steel arched solar greenhouse to resist external loads, such as wind and snow. There are the prominent instability and disaster that caused by insufficient stiffness of solar greenhouse under extreme weather conditions, such as snowstorms. In this study, the nonlinear stability analysis was conducted on the commonly-used sectionsteel arched solar greenhouse in Hebei using elastic-plastic mechanics and nonlinear finite element (FE). A refined FE model was established for the section-steel arched solar greenhouse. The greenhouse arch roof and the vertical sections on both sides were simulated using the Beam188 element in the element library of the universal FE analysis program ANSYS. The linear elements were used to fit the circular arc segments. Diagonal tension bars, vertical brace struts, and longitudinal tie bars were all simulated using Link10 element. The bottom of the vertical sections on both sides of the arch was assumed to be consolidated with the foundation. The steel was made of Q235, with an elastic modulus of 206 GPa, a Poisson's ratio of 0.3, and a density of 7 850 kg/m³. Geometric and material nonlinearity was considered to simulate the constitutive relationship of steel using an ideal elastic-plastic model, followed by von Mises yield criterion and bilinear kinematic hardening model BKIN. The stability performance and parameter analysis of solar greenhouse structure were carried out under snow loads. The stability capacity of solar greenhouse was determined under different parameters, such as steel-section type (flat elliptical, hollow rectangular and hat-shaped cross-section), greenhouse span (8, 10, and 12 m), and snow load distribution pattern (non-uniform distribution thickness and asymmetric distribution area). There was the quantitative influence of snow load distribution on the stability capacity of solar greenhouses. The load factor-displacement curves were combined with the deformation, stress, axial, and bending moment at different points of loading time. The static instability of solar greenhouses was explored from two aspects: intuitive phenomena and intrinsic essence. The conclusions were obtained as follows: The stability capacity of the steel component with a flat elliptical section in the solar greenhouse was increased by 21.0% and 44.2%, respectively, compared with the box and hat-shaped section. There was no out of plane instability in the same cross-sectional area and flange width of the steel component. The stability capacity of solar greenhouse was rapidly reduced with the increase of span. The stability capacity of solar greenhouse under non-uniform distribution of snow loads was reduced by the maximum of 63.8%, compared with the uniform. The maximum stability capacity of a solar greenhouse increased by 9.0% and 66.8% with only tension bars and brace struts, respectively. The findings can provide the technical guidance and theoretical reference for the anti-snow loads, stability and disaster prevention in the section-steel arch solar greenhouses. [ABSTRACT FROM AUTHOR]

Web-crippling was a usual failure in cold-formed steel due to the thin gauge steel. The high rate of web-crippling is the result of this beam failure. Past studies have discussed the web crippling range based on different beam thicknesses. However, the optimization of web crippling is not studied. Considering this, the reduction of web crippling rate is studied in this research work with the use of vulture optimal features. Henceforth, the current study proposed a novel intelligent vulture decision model (IVDM) to determine the proper Z-section beam thickness, which has reduced the web-crippling rate. The Strength of the cold-formed steel Z-section beam was ascertained by examining the beam's Strength under three distinct loading scenarios: point load, uniformly distributed load, and eccentric load. Additionally, the Z-section beam is designed on the ABAQUS platform, while the designed model is run in the MATLAB environment. Performing the various execution trails allowed for predicting the appropriate beam thickness range. As a result, the optimal beam thickness value for the Z-section beam is designed using the ABAQUS software. Ultimately, all other outcome parameters have shown that the suggested model has higher Strength and less Web-crippling compared to other models already in use. Here, the proposed IVDM has improved the web crippling rate by 4% than the compared existing approaches. It has been verified that the introduced model is highly suitable for web-crippling applications. [ABSTRACT FROM AUTHOR]

Introduction Many theories are found for subsurface drainage system design (Kumar et al., 2013). These were formulated by some of the soil characteristics that are important in designing and operating drainage systems. Most of these formulas have simplified and just involved flow parameters or assumed soil media as a maximum of two layers. In paddy fields, used equations for water table depth prediction have no accordance with field condition. Due to specific flow situations in these fields, much difference was observed in results (Darzi-Naftchali et al., 2013). The differences were because of special layered soil in paddy fields and soil hydraulic characteristics, hardpan layer existence formed in long cultivation and tillage, its effect on flow, and of course, lack of a suitable formula for these fields. So, designing rules for subsurface drainage in paddy fields needs investigation and implementation of new relations to predict the flow pattern suitably. Determination of design criteria and suitable formulas needed to predict flow network around drain tubes. Jafari-Talukolaee et al. (2017) reported in predicting water table profile between bilevel subsurface drainage in paddy fields due to the existence of resistance in vertical flow direction based on soil layers, and field results have no suitable agreement with analytical solution. Darzi-Naftchali et al. (2013), analyzing the effect of subsurface drainage systems on water balance and water table in paddy fields for a successive rice and canola cultivation season, obtained that shallow drainage systems were more influenced than deep drainage systems in water table control. The flow pattern of water towards the drain tube and the components of the flow network are the basis of the drainage system design. By determining the flow path towards the drains and the water table profile variation, the distance and depth of the drains in paddy fields can be determined with greater accuracy. Methodology This research was carried out in a drainage pilot of Sari Agricultural Sciences and Natural Resources University located in Sari town of Iran during the autumn and winter of 2018-19. The latitude and longitude of the region are 36.39° N and 53.04° E, respectively, and its height above sea level is -15 m. According to 10-year meteorological data, the average rainfall in the region is 643 mm, pan evaporation is 1222 mm and the average air temperature is 17.6 °C. The studied drainage system has a depth of 0.90 m and a spacing of 30 m. The length of the drainage line is 100 m, and the material of the pipes is a corrugated pipe with a diameter of 100 mm, which was installed with a slope of 0.2%. Mineral sand with specific granulation was used as cover. The field's soil texture up to a depth of 1.5 meters is silty-Clay with a clay content between 55-42%. Below the 1.5 m, the layer is a clay texture. Water table and drain discharge were measured daily, and horizontal and vertical hydraulic conductivity were measured. Discharges values, hydraulic conductivity of different layers, water table, and measured piezometric level were used to calculate vertical, horizontal, and radial loads. The procedure was that the vertical load was compared with formula (1). hv = q×Dv/k (1) The horizontal flow load was compared with formula (2). This equation, in which the flow to the drain is assumed to be completely horizontal, is known as the Donnan equation. hh = qLh²/8kDh (2) The radial load of the flow (hr) was calculated by the formula (3). hr = q × (L/πk) × ln aDr/u (3) The hydraulic conductivity was the same as the average hydraulic conductivity measured in the field (m day-1), and the flow rate was equal to the outlet flow rate (mm day-1). The value of Dv was considered equal to the water table to the drain level (m) and Dh = D+0.5h. The values of L were the same as the drainage distance (m), and Lh was equal to the difference between the drainage distance and the radial flow range (1.4 × D). In radial flow, the value of aDr is a parameter that depends on the geometric dimensions of the flow zone and the position of the drainage pipe relative to the impermeable layer. In some cases, the value of this parameter is considered equal to D. The amount of wetting medium of the inlet flow to the pipe (u), because in this study, the pipe was placed inside the trench with a mineral coating with a thickness of 10 cm on each side was equal to the wetting environment of the trench. By calculating the values of the flow components, their sums were matched with the values of the actual water table using the formula h= hv+ hh+ hr. The difference between the measured and calculated values was evaluated and compared using statistical indicators (paired t-test). The statistical indices were RMSE (mean square error), R² (correlation coefficient), and Ia (agreement index). Results and Discussion The results showed that the water table profile was horizontal and only dropped near the drainage. Hydraulic conductivity measurements showed that the soil included different layers, where a low permeability layer was observed at a depth of 30-60 cm, reducing vertical permeability and increased horizontal movement of water towards the drains. This condition has led to the leveling of the water table. Field soil stratification studies showed that the soil texture in the surface layer of the experimental field is lighter than the deeper layers. The average value of hydraulic conductivity above the drain (ground level to a depth of 0.9 m) is 0.23 m day-1, and the average value of hydraulic conductivity between the depth of the drain (0.9 m) to the impermeable layer (2 m) is equal to 0.15 m day-1 was achieved. Also, in the 30 to 60 cm layer, a layer with less hydraulic conductivity was observed than the surface layer, the same as the hardened layer. In a study of Vietnam paddy fields, a layer with a hydraulic conductivity of fewer than 0.09 m day-1 was observed beneath the surface layer at a depth of 60 to 70 cm (Nguyen, 2007). The depth curve of the water table measured at different distances from the drain showed that the drop of the water table occurred at a short distance from the drains, and at farther distances, the water table was horizontal. At a distance of one meter, about 90% of the water table has fallen, but at a distance of 3 meters, only 30% of the water table has fallen. The soil's multi-layered nature changes the flow lines' pattern to the drains, where the horizontal flow is more affected by the layers with high hydraulic conductivity and the vertical flow is affected by the layers with low hydraulic conductivity. Take (Oosterbaan and Nijaland, 1994). The values measured by piezometers are very different from the calculated vertical load values in the vertical flow discussion. The difference between the calculated and measured values and the low value of the calculated vertical load is due to the low discharge output from the drains. However, the high value of the measured difference between the piezometer of the surface layer and the level of the drainage base is due to the presence of the hardened layer and the slow penetration of water into the lower layer. There is a good and positive correlation between the measured values of piezometers and the calculated horizontal load. The calculated values of horizontal load and its measurement are somewhat close and show the high share of horizontal flow in paddy soils. The regression relationship between the values of radial load and the measured values shows the same trend. However, the difference between these two values in the radial current was greater than the horizontal current. According to the results, the contribution of horizontal flow was significantly higher than the other two components. The contribution of the vertical components is small and, in most cases, less than one percent. The radial component, which had a larger contribution than the vertical contribution, had a relatively significant effect of about 11%. Hamzeh et al., 2013, in their study of water table profiles between two bilevel drains in lands with layered soils, interpreted the large difference between the results of analytical solution and field measurements as follows; Since the soil of the experimental farm is composed of three layers with different permeability coefficients, this changes the pattern of flow lines to the drains. In particular, the limiting layer prevents vertical infiltration of water. Due to the increase of soil resistance against the water flow path, causes the flow lines to deviate from the radial state and be horizontal. Conclusion Calculating the flow components showed that when the water table was at a higher level, the total load was overestimated. Conversely, the total load was underestimated when the water table was at a greater depth. This condition is due to the discharge from the drains; when the water table is close to the ground, most of the water reaches the drainage trench and pipe by moving horizontally from above the hardened layer and has a high discharge. However, with the water table drop, the discharge enters the drain from the hardened layer or below it, mainly by radial movement, and less discharge comes out of the drain. Due to the presence of different layers in the soil and a layer with low hydraulic conductivity below the surface layer, the measured values of the flow components were very different from the calculated values. [ABSTRACT FROM AUTHOR]

Introduction. Active introduction of modular buildings into the practice of modern construction causes the necessity to develop methods of their calculation. At the same time, there are no specialized guidelines for the design of modular buildings. It is impossible to manage only with numerical methods of calculation for forming design recommendations. Therefore, the creation of an analytical method of calculation of modular buildings is an important area of research. The question of determination of forces in elements of modular buildings with bearing columns and rigid intramodular connections is considered.Materials and methods. The determination of forces in the elements of modular buildings from vertical loads can be carried out with high accuracy using well-known formulas of building mechanics. The main difficulty is the determination of dynamic effects (wind pulsation and seismic load). It is proposed to use a cantilever construction scheme with the decomposition of masses at the floor level. As a result of calculations, a set of inertial forces is formed from pulsation and seismic action. Modular programme was written to simplify the calculations. The programme is convenient for making preliminary and variant calculations and research of modular building structures.Results. The presented analytical method for determining the forces in the elements of modular buildings shows good convergence of the results with the finite element method. On a concrete example, it is shown that there is practically no discrepancy in determination of forces from vertical loads. The discrepancy from the combined effect of the static and pulsation components is 4.2–16.6 % for bending moments and 1.3–6 % for longitudinal forces. The discrepancy in determining the forces from the seismic load is within the range of 5–10 % for both bending moments and longitudinal forces.Conclusions. The method is convenient for application at the stage of qualitative assessment of design solutions, variant calculations and search for rational design solutions of modular buildings.

Tandem bicycles are used for all para-cycling events for visually impaired athletes. Tandems are structurally more challenging to design than solo bicycles: they must resist higher loading over a longer wheelbase, yet must still fit between the legs of the riders. Despite this, there is limited published work on tandem design. This paper presents a method for determining maximal loading of a tandem bicycle frame in racing scenarios. The only inputs required are the dimensions of the frame and the torques exerted by the riders. Outputs are the forces acting on the frame. The method is used to provide loads for structural analyses of tandem frames of different topologies. Twisting of the frame under a starting effort is shown to be the worst load case. The "double diamond" is shown to be the most efficient tubular frame design, on a stiffness per weight basis, but is only 2% superior to an "open" topology. [ABSTRACT FROM AUTHOR]

This study aims to clarify the influence of column foot joint size on the joint bearing capacity. Taking a Venlo greenhouse project in Zhuhai as the case, a systematic analysis was first implemented on the characteristic internal force of steel column foot. The center column foot joint was subjected to the axial tensile bending under wind load, due to the bending moment and shear force. The side column foot joint was mainly using axial tensile force, and subjected to axial tensile shear under wind load. Secondly, an optimal design was made on the column foot joint of the center and side column, according to "Code for Design of Concrete Structure", "Regulations for Design of Chemical Equipment Foundation", and "Manual of Concrete Structure". The edge distance of the anchor bolt for the column foot joint of the center column was 100 to 150 mm. The edge distance of the anchor bolt at the foot joint of the side column was 125 to 200 mm. Finally, the bending resistance to the foot joint of the center column, the shear resistance to the foot joint of the side column, and the failure mechanism were studied by numerical simulation and experiment. The results show that the failure of the center and side column was divided into the elastic, yield and ultimate bearing capacity stages. The yield point determined by the apogee accurately represented the moment, as the joint stiffness changed. The yield load and ultimate load of the three kinds of joint decreased with the reduction of the joint structure, the yield load of the central foundation short column joint decreased by about 10% per stage, and the ultimate load decreased by about 7% per stage. Once the edge distance of the anchor bolt in the side column joint was reduced by 25 mm, the two loads were reduced by about 20%. The failure mode of the central foundation short column joint was the concrete conical failure on the tension side. The failure mode of the side column joint was that the concrete wedge was pushed out. The diameter of the anchor bolt posed the greatest influence on the bearing capacity of the two joints under different structures, both of which were more than 15%. There was a small influence of the shear connector on the central foundation short column joint. The influence on the side column joint was less than 10%, due to the different load types. The smaller the sizes of the two joints were, the less outstanding the influence was. The thickness of the bottom plate shared the greater influence on the stiffness of the center column node and the lesser influence on the side column node. The shear connector had the lesser influence on the bearing capacity of the center column node and a greater influence on the bearing capacity of the side column node. The design requirements of embedded parts in “Code for Design of Concrete Structures” can fully meet the bearing capacity requirements of column foot bolt joints of greenhouse structures to resist horizontal forces, indicating the large bearing capacity reserve. The finite element modeling can be used to accurately simulate the mechanical properties and failure of the anchor bolt joint. The finding can also provide a strong reference to design the anchor bolt joint of multi-span columns in the greenhouse. [ABSTRACT FROM AUTHOR]

This study aims to improve the application effectiveness of discrete hydraulic actuators. The desired result is achieved by increasing the motion speed of the working body under limited technical conditions. One of the significant factors that limit the motion speed is the dynamic nature of the working body during the braking process. The braking process depends on the parameters of the actuator, the working speed and the inertial loads. The working speed and inertial loads may change during the operation process of the actuator, so they need to be adjusted accordingly. The braking process can also significantly affect the pressure in the hydraulic system of the actuator, therefore, it also needs to be considered during the design. The characteristics prediction of the braking process contributes to maximizing the working speed of the actuator under specific operating conditions, and it also lays the foundation for designing the new actuator scheme according to the specified requirements. The conducted study is based on the developed mathematical model of the discrete hydraulic actuator. The model is characterized by considering the nonlinear friction based on the LuGre model, the bidirectional motion of the asymmetric hydraulic cylinder, and the elastic properties of the fluid. A series of simulation experiments on the braking process of the hydraulic actuator in the discrete control mode were carried out. The quantitative relationship between the rod braking time, the maximum peak pressure in the hydraulic cylinder chambers, the value of the initial rod velocity and the inertial mass of the moving parts are determined. Based on the research results it is possible to predict the braking time of the rod and the maximum peak pressure in the hydraulic cylinder chambers under various operating conditions and inertial loads. These predictions can be used in the settings and design process of hydraulic actuators. [ABSTRACT FROM AUTHOR]

Reinforced concrete bridge size box culverts (RCBCs), with structure length greater than or equal to 6.1 m (20 ft), are an integral part of the transportation infrastructure. Load rating RCBCs is essential, and the critical component is generally the top slab. The objective of this study is to propose a triage methodology to quickly and conservatively determine the rating factor (RF) for the top slab of a two-cell RCBC. The derivation of the demand equations is illustrated in this manuscript for the top slab and the AASHTO HL-93 live load. The finite element program CANDE is used to evaluate the influence of the cell clear height (H), cell clear span (S), fill height (HF), and the backfill modulus (E) on the demand loads. Multiple regression analyses showed that H had no significant effect on the dead load demands, while H and E had no significant effect to the live load demands. Conservative linear demand equations (LDEs) are presented to calculate the dead and live load demands leading to a quick determination of the RF. LDEs for single and multi-cell culverts can be derived following the LDE procedure outlined herein. [ABSTRACT FROM AUTHOR]

The plunger is the core component of the sucker rod pump. Its rapid wear and premature failure severely limit the efficiency and productivity of oil and gas production. Diamond-like carbon (DLC) films, due to their high hardness, high wear resistance and low friction coefficient, have great research prospects for the development of long-life and high-reliability sucker-rod pump plungers in oil production environments. Therefore, in this paper, to simulate the friction behaviour and influence mechanism of the DLC film in an oil production environment, three molecular dynamics friction models of Fe–Fe, DLC–Fe and DLD–DLC were established. It is found that with increasing load, the friction coefficients of DLC–Fe and DLD–DLC are smaller than that of Fe–Fe in the light oil reservoir environment. In particular, when the mating pair is DLC–DLC, a superlubricity state of 0.0007 is even achieved. This will greatly increase the service life of the plunger of the sucker rod pump in the oil production environment. Further investigation revealed that the low friction of the DLC film in an oil production environment is mainly due to the weak interaction between light oil molecules and the DLC layer, so that it does not cause adhesive wear with the friction surface while lubricating the surface. [ABSTRACT FROM AUTHOR]

Wind turbines often have lower performance and experience higher loading in real operation compared to the original design performance. The reasons stem from the influences of complex atmospheric turbulence, blade contamination, surface imperfection and airfoil‐shape changes. Engineering models used for designing wind turbines are limited to information derived from blade sectional datasets, while details on the three‐dimensional blade characteristics are not captured. In these studies, a dedicated strategy to improve the prediction accuracy of engineering model calculations will be presented. The main aim is to present an elaborated effort to obtain a better estimate of the turbine loads in realistic operating conditions. The present studies are carried out by carefully utilizing data from high fidelity Computational Fluid Dynamics (CFD) computations into Blade Element Momentum (BEM) and Vortexline methods. The results are in a good agreement with detailed field measurement data of a 2.3 MW turbine. The studies are further extended to a large turbine having a rated power of 10 MW to provide an overview of its suitability for large turbines. Finally, calculations of the wind turbine under a realistic IEC design load case are demonstrated. The studies highlight important considerations for engineering modeling using BEM and Vortexline methods. [ABSTRACT FROM AUTHOR]

The Hammerstein integral equation with loads on the desired solution is considered. The equation contains a parameter for any value of which the equation has a trivial solution. Necessary and sufficient conditions are obtained for the coefficients of the equation and those values of the parameter (bifurcation points) in its neighborhood the equation has a nontrivial real solutions. The leading terms of the asymptotics of such branches of solutions are constructed. Examples are given illustrating the proven existence theorems

The ever-increasing span can be found in the single-pipe arch solar greenhouse in recent years. But the cross-section of the rods cannot be adjusted in real time. This study aims to ensure the structural Safety Issues in this case. The research object was taken as the 12m-span solar greenhouse with a flexible thermal insulation wall. A test example was selected as the solanaceous solar greenhouse in Beijing of China. An oval tube was used with a commonly-used section of 80 mm×30 mm×2.0 mm (Height×width×wall thickness). A ‘Midas-Gen finite element software’ was utilized to analyze the greenhouse hanging, and boundary conditions. Finally, the structural parameters were optimized, according to the national standard "Agricultural Greenhouse Structure Load Code" (GB/T 51183-2016) and "Agricultural Greenhouse Structure Design Standard" (GB/T 51424- 2022). The results show that the maximum stress was 1 146.7 N/mm2, when the crop load was suspended at two points and the column feet were hinged in the greenhouse. The position of the maximum stress was the hanging point on the rear wall. The crop load C was the main control load, and the average stress value was 445.4 N/mm2 at other positions. Therefore, the small number of hanging points and the large concentrated load at the hanging points were attributed to the extremely uneven distribution of the internal force of the arch frame. The structural parameters were optimized to increase the number of hanging points, in order to disperse and reduce the local concentrated load. As such, the peak value of concentrated stress was effectively reduced to improve the uniformity of the internal force distribution of the whole structure. Furthermore, the arrangement of hanging loads was also optimized to combine with the local reinforcement and adjustment of boundary conditions. The internal force of the structure was reasonably distributed to reduce the stress of the structural skeleton. Further research was recommended that: 1) The increasing hanging points of the crops can be expected to effectively reduce the peak value of internal force. Once the hanging points increased to the three-point type, the hanging load degenerated into a secondary control load, whereas, when increased to the four-point type, the crop load quit the control role. 2) The rest direction was the partial strengthening of weak parts. The rear wall was adjusted from a single tube to a lattice column, while the maximum stress was reduced by about 48%, indicating a more significant improvement. 3) The connection form of column feet was adjusted, when fixed the front and rear column feet of the solar greenhouse with the single-tube arch frame. Once the rear wall arch frame was adjusted to the lattice columns, the hinged form was used to optimize the front column foot. This finding can also provide a strong reference for the structural form and structural materials of flexible insulation wall oval tube single tube arch type solar greenhouse. [ABSTRACT FROM AUTHOR]

Background: There are limited data on the in vivo natural kinematics of the lumbar spinous process. This paper intends to explore the effect of lifting load on the in vivo movement mode of the lumbar spinous process and its biomechanical changes. Methods: Ten asymptomatic subjects between the ages of 25 and 39 underwent CT scans of the lumbar spine in the supine position, and 3D models of L3-L5 were constructed. Using a Dual Fluoroscopy Imaging System (DFIS), instantaneous orthogonal fluoroscopic images of each subject's flexion–extension, left–right bending, and left–right rotational movements were taken under different loads (0 kg, 5 kg, 10 kg). The supine CT model was matched, using computer software, to the bony contours of the images from the two orthogonal views, so that the instantaneous 3D vertebral position at each location could be quantified. A Cartesian coordinate system was ultimately constructed at the tip of the spinous process to obtain the 6DOF kinematic data of the spinous process. Results: In different postural movements of the trunk, there was no significant difference in the rotation angle and translation range of the lumbar spinous process under different loads (P > 0.05). In flexion to extension motion, spinous processes mainly rotate < 4° along the medial and lateral axes and translate < 4 mm along the craniocaudal direction. In the left–right bending motion, spinous processes mainly rotate < 5° along the anterior and posterior axes, and the translation is mainly coupling < 2 mm. In the rotational motion, the spinous process is mainly coupled motion, the rotation range is less than 3°, and the translation range is less than 2 mm. The distance between spinous processes measured in the supine position was 6.66 ± 2.29 mm at L3/4 and 5.08 ± 1.57 mm at L4/5. Conclusion: The in vivo kinematics of the lumbar spinous process will not change significantly with increasing low load. In complex motion, the spinous process is dominated by coupling motion. [ABSTRACT FROM AUTHOR]

Abstract Background Varroa destructor is the major ectoparasite of the western honey bee (Apis mellifera). Through both its parasitic life-cycle and its role as a vector of viral pathogens, it can cause major damage to honey bee colonies. The deformed wing virus (DWV) is the most common virus transmitted by this ectoparasite, and the mite is correlated to increased viral prevalence and viral loads in infested colonies. DWV variants A and B (DWV-A and DWV-B, respectively) are the two major DWV variants, and they differ both in their virulence and transmission dynamics. Methods We studied the transmission of DWV between bees, parasitic mites and their offspring by quantifying DWV loads in bees and mites collected in in vitro and in situ environments. In vitro, we artificially transmitted DWV-A to mites and quantified both DWV-A and DWV-B in mites and bees. In situ, we measured the natural presence of DWV-B in bees, mites and mites’ offspring. Results Bee and mite viral loads were correlated, and mites carrying both variants were associated with higher mortality of the infected host. Mite infestation increased the DWV-B loads and decreased the DWV-A loads in our laboratory conditions. In situ, viral quantification in the mite offspring showed that, after an initially non-infected egg stage, the DWV-B loads were more closely correlated with the foundress (mother) mites than with the bee hosts. Conclusions The association between mites and DWV-B was highlighted in this study. The parasitic history of a mite directly impacts its DWV infection potential during the rest of its life-cycle (in terms of variant and viral loads). Regarding the mite’s progeny, we hypothesize that the route of contamination is likely through the feeding site rather than by vertical transmission, although further studies are needed to confirm this hypothesis. Graphical Abstract

The article is devoted to the study behavior of car structural elements during operation and in extreme conditions that occur during road traffic accidents (RTA). At present, a promising direction of research in this area is the development methods based on the analysis of structural elements of a damaged car deformed as a result an accident and the restoration of the energy exchange pattern upon impact. Research carried out both theoretically and experimentally. Theoretical studies based on the methods of theoretical and applied mechanics, strength of materials and elasticity theory. The goal is to improve the methodology for conducting an autotechnical examination of an accident. Method or methodology of work: solving inverse problems of continuum mechanics. Results: a technique developed for determining the initial speed of a car before an accident based on the results measuring deformed structural elements. The accuracy determining the initial speed of the car is proportional to the accuracy measuring the deformations damaged car. Scope results: it is advisable to apply the obtained results when conducting an autotechnical examination of an accident.

In alpine ski disciplines, it is common for competitors to record incomplete runs. In some instances, up to 40% of competitors have failed to complete a course. Possible reasons include incorrect preparation of skiers (lack of adequate motor preparation) and poor tactical approaches. However, there are also some errors in the setting of gates on a course. The aim of this paper is to determine the objective difficulty coefficient of alpine skiing competition courses, based on course geometry and the kinematic parameters of the run. This research monitored alpine skiers during the FIS World Cup. All four alpine skiing disciplines (i.e., downhill, super giant, giant slalom, and slalom) were considered. The average value of the coefficient of difficulty (W.tr) was the highest for the downhill style runs and amounted to 1.20, the super giant and the giant had comparable values of 1.13–1.14, and for the slalom, the W.tr value was the lowest at 0.97. Based on the determined coefficients of route difficulty, it is possible to derive a quantifiable metric to estimate the degree of risk associated with different sections of a course. [ABSTRACT FROM AUTHOR]

This paper addresses unpaved and paved roads improved with geosynthetics, such as geotextiles, geogrids and geocells. The paper examines the mechanisms associated with the use of geosynthetics to improve roads, describes the principles of the design methods used to quantify the benefits of geosynthetics used in unpaved and paved roads, presents case histories to demonstrate the use of geosynthetics to solve challenging road problems, and discusses the relevance of tests and trials to real roads. This paper is supplemented by four presentations in pdf format that contain more than 800 slides. These four presentations are updated versions of the four presentations made during a one-day short course at the 11th International Conference on Geosynthetics held in Seoul, Korea, in September 2018. The paper that follows contains a summary of each of the four presentations, with special emphasis on key issues. [ABSTRACT FROM AUTHOR]

• An Ahmed body under unsteady flow conditions is investigated experimentally in wind tunnel and compared with steady flow. • Drag, lift and pitching moment performances are measured by high resolution balance and wake details by High-Speed PIV. • Increment of drag and lift coefficients with yaw angles and slight decrease with amplitude of oscillation are observed. • Wake alternates between symmetrical and non-symmetrical patterns related to yaw and forcing blade angular positions. • This investigation allows improving assisted-driving vehicles in unsteady gusts and wakes, avoiding misleading control. This paper experimentally characterizes unsteady effects and flow fields around the Ahmed Body, by analyzing global forces and detailed wake effects. The results are compared to those obtained under steady conditions, with varying wind tunnel velocities and different yaw angles between the model and the free stream. Unsteady fields are generated by means of oscillating blades positioned at the inlet of the test section, whose amplitudes and frequencies can be easily controlled. Specifically, low frequencies, around a few Hertz, as those in the typical range generating load oscillations on vehicles, are considered. The results in terms of force coefficients, obtained by a dynamometric balance, and velocity fields, obtained by Particle Image Velocimetry, are processed in order to derive time-average statistics and also phase-average statistics, as related to forcing blade instantaneous positioning. This type of analysis can be performed thanks to the high temporal resolution of measurement systems, around 100 Hz for the force measurements and around 4000 Hz for the velocity measurements. Results in steady conditions well compare with previous results in references, both as functions of wind tunnel velocity and yaw angles. In unsteady conditions, whatever amplitude is considered, time-average drag and lift coefficients and their dependence on yaw angle are consistently lower compared to the steady case. Phase-averaged coefficients in unsteady conditions can oscillate by around 20 % in comparison to time-average values and these fluctuations are strongly dependent on yaw angle and amplitude of oscillations, thus suggesting that they both contribute to instantaneous loads. Present investigations are related to improvements in set-up of control systems in assisted-driving (self-driving) vehicles. [ABSTRACT FROM AUTHOR]

Summary The progression of wind turbine technology has led to wind turbines being incredibly optimized machines often approaching their theoretical maximum production capabilities. When placed together in arrays to make wind farms, however, they are subject to wake interference that greatly reduces downstream turbines' power production, increases structural loading and maintenance, reduces their lifetimes, and ultimately increases the levelized cost of energy. Development of techniques to manage wakes and operate larger and larger arrays of turbines more efficiently is now a crucial field of research. Herein, four wake management techniques in various states of development are reviewed. These include axial induction control, wake steering, the latter two combined, and active wake control. Each of these is reviewed in terms of its control strategies and use for power maximization, load reduction, and ancillary services. By evaluating existing research, several directions for future research are suggested.

Abstract Background Lumbar facet joints (LFJs) are usually related to the pathogenesis of the spine. The purpose of this paper is to study the effects of lifting load on the motion of lower lumbar facet joints in vivo. Methods Ten healthy volunteers aged 25 ≤ 39 years, 5 males and 5 females, were recruited. Using a dual fluoroscopy imaging system (DFIS) combined with CT, firstly, the L3-S1 segment image scanned by CT was converted into a three-dimensional model. Then, the lumbar motion images of L3-S1 vertebrae taken by the DFIS under different loads (0 kg, 5 kg, 10 kg) and different body postures (maximum flexion and extension, maximum left and right bending, and maximum left and right torsion) were captured. Finally, in the Rhino software, the instantaneous motion state of the lumbar spine is reproduced by translation and rotation according to the anatomical structure of the lumbar spine and the previous images. With the help of computer software, a Cartesian coordinate system was placed in the center of each articular surface to measure the kinematics of the articular process and to obtain 6DOF data under different loads (0 kg, 5 kg, 10 kg) in the lumbar facet joints. Results In the flexion and extension of the trunk, weight bearing reduced the translational range in the mid-lateral direction. In the L3/4 segment, the lateral translational range of the left and right facet joints gradually decreased with increasing load, and the translational range at 0 kg was significantly greater than that at 10 kg (left side: 0 kg, 0.86° ± 0.57°, 10 kg, 0.24° ± 0.26°, p = 0.01; right side: 0 kg, 0.86° ± 0.59°, 10 kg, 0.26° ± 0.27°, p = 0.01). In the L5/S1 segment, the translation range of the LFJ at 0 kg was significantly greater than that at 10 kg (p = 0.02). Other bending and rotation movements were not found to cause differential changes in the 6DOF of the LFJ. In bending, the rotation range was the largest in the L3/4 segment (p

The function of the hydraulic damper of the high-speed Multi-Electric-Units (EMUs) is to offer viscous damping to reduce the vibrations and to keep the stability of the vehicle. It is the key component and it has great effects on the high-speed EMU dynamics. A new hydraulic damper dynamics model including two clamping points stiffness, a viscous damping and two centralised masses, is presented in this paper. A high-speed vehicle–track interaction dynamics model is developed, in which the new hydraulic damper dynamics model is introduced in it to investigate the damper and vehicle dynamics. With numerical simulation, the clamping point loads and damping forces of four types of dampers of the vehicle are obtained. The reliability of the new damper dynamics model is validated with comparison between the simulation results and the field test results. The availability of the new damper dynamics model is confirmed with the comparison of the results between a simplified damper dynamics model and the new damper dynamics model for two types of high-speed EMUs in China. With the help of the new damper dynamics model, the optimised clamping point stiffness of the dampers and the effect of the damper mass on the vehicle system dynamics are discussed. The investigation results show that the vibration difference between the damper and the connected components of the vehicle could be obtained. [ABSTRACT FROM AUTHOR]

The stabilizer link, also known as the anti-roll bar link or anti-roll bar link, is an important component of a vehicle's suspension. It plays a major role in keeping the vehicle stable during cornering and reducing unwanted vehicle movement. The main function of the anti-roll bar is to reduce body roll during cornering, i.e. when the vehicle turns, the weight is transferred from one wheel to the other on the same axle and this can lead to body roll. The stabiliser linkage provides an inertial link between the two suspension axles and prevents lateral roll. Stopping the roll phenomenon contributes to better vehicle handling and to maintaining optimal contact of the wheels with the road surface. This paper presents studies on a stabilizer bar linkage made of a polymer often used in the automotive industry, namely acrylonitrile butadiene styrene (ABS). This research will show by finite element method the limit values supported in tension for each end with ball joints and identify the areas where concentrated loads are found. The study also uses the application of reverse engineering by scanning a stabilizer bar linkage in the vehicle suspension subassembly. [ABSTRACT FROM AUTHOR]

This work presents the results of experiments on the physical modeling of the interaction of long tsunami-type waves with floating gas storage. Loads under wave action are assessed, and the results are analyzed. Conclusions are drawn on the nature of the load dependence on the floating object orientation relative to the impact direction of the tsunami wave and the maximum tsunami height. [ABSTRACT FROM AUTHOR]

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Metal towers as supports for a cable-driven parallel robot have been considered in this paper. Their loads and strains have been modeled. The most dangerous combination of loads affecting the tower during the entire operation period has been calculated. The major design principles of a facility used for this purpose have been stated based on an analysis of the calculation results. The recommendations for further study and optimization of the design solutions have been given. This study has made it possible to assess movements of the support elements of a cable-driven robot caused by strains of the towers under load, which should be taken into account in the control system of the cable-driven robot when generating the program motion laws. [ABSTRACT FROM AUTHOR]

The use of wireless sensor networks (WSNs) for data collection is widespread. The resource constraint is an important factor in WSN communications design. The issue arises naturally in WSNs as a result of uneven energy consumption caused by multi-hop routing and dynamic network models, which substantially affects network lifetime. The nodes are dispersed over distant sensing areas and are powered by finite or limited energy batteries that are difficult to replace. The energy of nodes is reduced as a result of changes in network topology or the network's lifespan and the main intention of this research is to figure out how to make sensor networks last longer. The suggested study work focuses on a specific routing strategy for WSNs that employs the AO-star algorithm with a Fuzzy approach and link stability for extending the network lifetime. The technique chooses the optimum routing path by the sensing point to the receiving node based on how much energy is consumed, the smallest number of nodes with the shortest latency, and lower transmission loads with higher throughput. To compare the proposed strategy's efficiency in energy consumption balancing and network lifespan enhancement, the proposed technique may achieve a 30% longer average network lifetime than the A-star algorithm. [ABSTRACT FROM AUTHOR]

The aim of this work was to numerically determine the influence of aerodynamic loads on the value of the resonant frequency of the compressor blade. The object of the research was the 1st stage compressor blade of the PZL-10W engine. As part of the research, analytical calculations of the resonance frequency were performed and compared with the literature ones (first, second, and third forms of forced vibrations). In the next step of the investigation, a computational model of the compressor stage (fluid domain and rotors) was built and FSI analysis was performed. This analysis was based on CFD modeling of the state of aerodynamic loads on the blade surfaces, and then these values were imported as external loads for the structural analysis, which was the basis for the modal analysis, in which the resonant frequency of the first three vibration modes was determined. As part of the analyzes, both the influence of aerodynamic loads and the rotational speed of the compressor rotor were verified. Thus, it was possible to evaluate the influence of both the rotational speed (and the arising centrifugal force) and the influence of the emerging aerodynamic load. The results obtained will allow for the assessment of the impact of the aforementioned operating conditions of the aircraft engine on the resonance frequency, which in turn may translate into the durability of critical components of the aircraft engine. [ABSTRACT FROM AUTHOR]

The paper addresses non-linear vibrations of offshore jack-up drilling platforms loaded by sea waves and wind in their stationary condition using the perturbation method. Non-linearity of dynamic equations of motion for fixed offshore platforms yields from two factors. The first is load excitation generating non-linear velocity coupling in a dynamic system. This coupling is inherent in the modified Morison equation, involving the excitation function in the form of the sum of the inertial and velocity forces of sea waves, taking into account relative wave–structure kinematics. Moreover, the wind acting on the exciting side causes similar effects. The second source is the subsoil–structure interaction problem, modelled by a system of springs and dashpots that yields stochastic non-linearity of the dynamic system. The matrix equations of structural motion in FEM terms are set up. The perturbation method is adopted to determine the mechanical response of the system, making it possible to determine response spectra of the first and the second approximations for displacements and internal forces of the platform. The paper is the continuation of research detailed in the paper [1]. It is assumed, that the fluctuation parts of the dynamic loading forces are in line with the direction of sea wave propagation. Sea current and lift forces effects are neglected in this study. A numerical example refers to structural data of the Baltic drilling platform in the stationary configuration, i.e. when three legs support the deck above the seawater level.