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In this study, a three-dimensional thermal analysis of the laser sintering additive manufacturing process was conducted. Analytical heat sink methods and numerical finite element analysis in Abaqus software were employed to assess the thermal behavior of the workpiece. Comparing the analytical method used in this study with those in the existing literature reveals the superiority of the results obtained in this research. Additionally, it has been demonstrated that the numerical and analytical results in this study are in good agreement with each other. Furthermore, the proposed method in this study has yielded significant findings, indicating its applicability in addressing the complexity of the problem. The findings demonstrated that optimizing the temperature distribution is attainable through adjustments to the initial workpiece temperature and scanning speed. [ABSTRACT FROM AUTHOR]

This paper investigates and analyzes the dynamic response of asphalt pavement under pavement-unevenness excitation based on an orthogonal vector function system and efficient DVP (dual variable and position) method. Firstly, starting from the pavement unevenness of the vehicle excitation source, the pavement-unevenness excitation is established by using the filtered white-noise method, and the random load of the vehicle model is obtained by simulation. Then, based on the basic governing equation of the road-surface problem under the random load, the analytical solution of the road-surface mechanical response is obtained by using the orthogonal vector function system and DVP method. The effects of pavement-unevenness grade, vehicle speed, vehicle load, interlayer contact condition, and transverse isotropy on the mechanical response of the road surface are analyzed via the analytical results. The results show that DVP can effectively solve the dynamic response of pavements under the excitation of pavement unevenness; in addition, it can also be applied to certain situations, such as transverse isotropy of materials and interface conditions. The results show that the pavement unevenness does not affect the average stress and strain of each layer but has a significant effect on the peak value and dispersion degree. An increase in vehicle speed causes a peak in strain and a larger coefficient of variation. Poor bonding between interfaces can lead to increased stress and strain at the bottom of the surface layer. [ABSTRACT FROM AUTHOR]

The electromagnetic vibration level is one of the important evaluation indicators of permanent magnet synchronous motor (PMSM) . In order to effectively suppress the electromagnetic vibration of PMSM, the analytical analysis model of the radial electromagnetic force generated by the interaction of rotor permanent magnet magnetomotive force, stator winding current magnetomotive force and stator slot was established. Then the field-circuit coupling analysis model of the variable parameter vector control system of PMSM was established. Taking a 11 kW interior PMSM as a prototype, the acoustic frequency spectrum of the electromagnetic vibration noise generated by the main low-order electromagnetic force during the stable operation of the motor was obtained using the mechanical impedance method, and the frequency of the low-order electromagnetic force that plays a major role in the electromagnetic vibration of the motor was determined. Finally, the genetic-ant colony algorithm was used to study weakening methods of the low order electromagnetic force with the above frequency by optimizing the stator slot parameters of the motor, so as to effectively suppress the electromagnetic vibration of the motor. The results show that the stator slot parameters determined by the method proposed can effectively suppress the electromagnetic vibration of the motor, and have little impact on the operating performance of the motor. [ABSTRACT FROM AUTHOR]

The effect of inclined third-body perturbation on the perturbed body's inclination evolution has been investigated extensively. However, under various initial orbital elements, the exact effect of the J 2 perturbation and the inclined third-body perturbation on perturbed body's inclination is still an open problem. In this paper, we use a simplified model for long-term orbital variations to analyze the free and forced inclinations for almost circular orbits with low inclinations. We analyze the influence of the J 2 perturbation on the inclination evolution under various initial orbital elements. The results show that the J 2 perturbation consistently decreases the maximum value of the inclination. Besides, the J 2 perturbation either decreases the amplitude of the inclination's oscillation, or enables the perturbed body to orbit closer to the equator of the central body. These effects enable the objects with initially low inclinations to maintain their orbits near the equator of the central body for a long time. The results of the study are applied to circum-Jovian orbits and the triple asteroid system 87 Sylvia. [ABSTRACT FROM AUTHOR]

Excavation can induce the settlement deformation of adjacent buried pipeline. Obtaining the deformation is of great significance for evaluating the normal use and safety of pipeline. In this study, based on the elastic foundation beam theory, the calculation formula of the settlement displacement of buried pipeline is derived, and the influence of the two parameters of the surface center settlement and the calculation length on the settlement displacement of pipelines is emphatically analyzed. According to the geometric relationship between the buried pipeline and the edge of the foundation pit, the calculation length can be used to divide into five working conditions. The rationality of the analytical method is verified by comparing with two cases. In the case of excavation in Beijing, the spatio-temporal variation rules of settlement displacement of buried pipeline were analyzed. The results show that the variated trend of the calculated settlement displacement in different periods is consistent with that from measurement, but the calculated value is slightly higher than the measured value. The surface center settlement has a significant influence on the pipeline settlement displacement. larger input causes more concave settlement curve, and smaller input leads to smoother settlement curve. The decreasing rate of settlement displacement increases from the central point to end, and decreases near the boundary point, with the range of about one tenth of the calculated length. The proposed method in this study is conservative in the evaluation of pipeline settlement, which is a supplement to the existing settlement calculation theory of buried pipelines, and can provide a important information for predicting the distribution of pipeline settlement in the early stage of construction.

In recent years, many countries have been confronted with an extended period of drought, necessitating innovative water supply solutions for both human consumption and agricultural irrigation. In response, wastewater treatment plants (WWTPs) have emerged as pivotal agents in water recycling, catering to agricultural needs and environmental considerations. These plants facilitate the transformation of wastewater into potable or irrigation-ready water. Amidst the array of WWTP designs, the "Continuous-Station" holds a distinctive position, featuring a monolithic steel-structure meticulously crafted from either conventional or stainless-steel. Presently, the prevalent approach involves the application of anti-corrosion paint to protect this monolithic structure from the corrosive effects of aggressive substances present in wastewater. However, an innovative strategy is being explored - the incorporation of tungsten, an anti-corrosive element, into the stainless-steel alloy. This integration shows promising potential to enhance resilience against the relentless degradation forces within wastewater, simultaneously bolstering the mechanical properties of the steel. This research paper exclusively focuses on analyzing, analytically, the hydrostatic bending performance of WWTP structural components infused with nano-tungsten-particles. The range of incorporation spans from a baseline of 0%, representing the steel without any infusion, to an optimal threshold of 30% relative to the overall volume of the steel matrix. The elastic-properties of the composite steel-tungsten alloy are characterized using Mori-Tanaka's homogenization model. The WWPT structural components are simplified as plates and analyzed using an advanced mathematical model based on the refined plate theory. The outcomes underscore a notable enhancement in flexural strength by augmenting the fraction of tungsten nanoparticles within the stainless-steel matrix. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin University of Science & Technology is the property of Journal of Harbin University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The shear behavior of basalt fiber–reinforced polymer-reinforced seawater–sea sand concrete (BFRP-SSC) beams was investigated experimentally. The effects of several factors, including stirrup diameters (8, 10, and 12 mm), stirrup spacings (100, 125, and 150 mm), and shear span-to-depth ratios (1.55, 1.95, and 2.35), were considered. The results demonstrated that the shear mechanism of the diagonal section of BFRP-SSC beams could be explained using the arch truss model. Moreover, the shear span-to-depth ratio significantly influences the shear capacity, bending stiffness, diagonal crack width, and shear failure mode of beams, with diagonal compression failure occurring in beams with a ratio of 1.55 and shear compression failure occurring in beams with a ratio between 1.95 and 2.35. In addition, the actual shear capacities of 72 BFRP-reinforced concrete (BFRP-RC) beams were compared to the results obtained by five design provisions. Correction coefficient of shear span-to-depth ratio, modification to stirrup spacing, correction equation of stirrup strain, and shear contribution coefficient of stirrups were proposed to modify the shear equation in ACI 440.1R-15. The results of the modified shear equation showed a good agreement with the actual shear capacities of beams. The findings of this research have theoretical significance for the design and practical application of BFRP-SSC beams in marine construction. [ABSTRACT FROM AUTHOR]

Cancer is the world’s second-biggest cause of death, accounting for roughly 10 million deaths in 2020 and estimated to reach 16 million by 2040. In this study, we propose a novel technique for the treatment of tumor models with a power-law kernel with the Sumudu transform. The analysis was made for a generalized form of analytical solution that is unique and Picard K-stable by using Hilbert and Banach space results. The model investigates the Ulam-Hyers-Rassias stability, uniqueness of solutions, and impact of fractional derivatives with the power-law kernel. Reproductive number analysis with an equilibrium point shows the bounded solution in the feasible region. In the end, numerical simulations are drawn through figures at different fractional and fractal dimensions for the dynamics of treatment and the growth of normal cells. The analysis shows crucial criteria for system stability, ensuring the efficacy of therapeutic interventions through novel mathematical and biological insights. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology & Engineering Geology / Shuiwendizhi Gongchengdizhi is the property of Hydrogeology & Engineering Geology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Unbonded steel-mesh-reinforced rubber bearings (USRBs) have been proposed as an alternative isolation bearing for small-to-medium-span highway bridges. It replaces the steel plate reinforcement of common unbonded laminated rubber bearings (ULNR) with special steel wire meshes, resulting in improved lateral properties and seismic performance. However, the impact of this novel steel wire mesh reinforcement on the ultimate compression capacity of USRB has not been studied. To this end, theoretical and experimental analysis of the ultimate compression capacity of USRBs were carried out. The closed-form analytical solution of the ultimate compression capacity of USRBs was derived from a simplified USRB model employing elasticity theory. A parametric study was conducted considering the geometric and material properties. Ultimate compression tests were conducted on 19 USRB specimens to further calibrate the analytical solution, considering the influence of the number of reinforcement layers. An efficient solution for USRBs' ultimate compression capacity was obtained via multilinear regression of the calibrated analytical results. The efficient solution can simplify the estimation of USRBs' ultimate compression capacity while maintaining the same accuracy as the calibrated solution. Based on the efficient solution, the design process of a USRB with a specific ultimate compression capacity was illustrated. [ABSTRACT FROM AUTHOR]

This paper investigates and analyzes the dynamic response of asphalt pavement under pavement-unevenness excitation based on an orthogonal vector function system and efficient DVP (dual variable and position) method. Firstly, starting from the pavement unevenness of the vehicle excitation source, the pavement-unevenness excitation is established by using the filtered white-noise method, and the random load of the vehicle model is obtained by simulation. Then, based on the basic governing equation of the road-surface problem under the random load, the analytical solution of the road-surface mechanical response is obtained by using the orthogonal vector function system and DVP method. The effects of pavement-unevenness grade, vehicle speed, vehicle load, interlayer contact condition, and transverse isotropy on the mechanical response of the road surface are analyzed via the analytical results. The results show that DVP can effectively solve the dynamic response of pavements under the excitation of pavement unevenness; in addition, it can also be applied to certain situations, such as transverse isotropy of materials and interface conditions. The results show that the pavement unevenness does not affect the average stress and strain of each layer but has a significant effect on the peak value and dispersion degree. An increase in vehicle speed causes a peak in strain and a larger coefficient of variation. Poor bonding between interfaces can lead to increased stress and strain at the bottom of the surface layer.

The primary objective of this study was to enhance the mechanical properties of soils through the incorporation of fibers. To this end, we introduced and tested a novel branched fiber with a distinctive shape and mechanism of action in the laboratory setting. Unconfined compressive strength and shear strength were measured for both unreinforced and reinforced soil sample, using ordinary and branched fibers. The results clearly indicate a substantial improvement in the compressive and shear strength of the reinforced soil, particularly after a specific percentage of fibers were added. Notably, the improvement was more pronounced when using branched fibers. Furthermore, the cohesion and internal friction angle of the reinforced soil increased by 20% and 28%, respectively, when employing the branched fiber. In addition to experimental testing, an analytical analysis was conducted, leading to the development of an equation that accurately predicts the behavior of the branched reinforced soil under shear loading. This proposed analytical approach demonstrated excellent agreement with the experimental data. In summary, these findings strongly support the conclusion that the novel branched fiber represents a highly effective means of enhancing the mechanical properties of soils, particularly when compared to traditional fibers. [ABSTRACT FROM AUTHOR]

Aluminium alloys are widely used in automotive and aerospace fields due to their material properties such as low density and high strength. In this experimental performance, AA2024, AA6061, and AA7075 alloy materials were cut in desired form by water jet (angle value ranges: between 0.0 and1.0 by 0.10 increments) processes. The fellow T6 heat treatment step was determined for the waterjet cut samples (Treatment for 2 h at 510°C followed by aging at 160°C for 1-h periods up to 15 h). After dissolution and after each hour of aging heat treatment, the hardness and vibration properties of the samples were investigated. FESEM, EDS, MAP, and microhardness data were obtained to determine the effects of applied heat treatments. As a result of the experiments, it was observed that the applied aging heat treatments increased the hardness, while no significant difference in vibration occurred. In addition, it has been shown experimentally and analytically that the natural frequency values of the beam can be changed by changing the cross-sectional angle of the beam. The experimental and analytical analyzes of the built-in beams were close to each other. The reason for the difference between them is the use of the Euler-Bernoulli beam in the analytical analysis and the neglect of the shear forces. [ABSTRACT FROM AUTHOR]

Shape memory polymer (SMP) signify a new category of responsive polymers characterized by their capability to undergo significant shape changes and then revert to their initial shape when exposed to specific stimuli. They are known by their low mechanical properties; however, when integrated into fiber-reinforced composites a considerable characteristics enhancement is achieved. Modeling the thermomechanical behaviour of these materials is crucial task to understand their shape fixity and recovery. However, the available models in the literature are sophisticated and not easy to implement. In this study a simplified mathematical model is presented, based on the stimulus temperature-time relation, to determine the shape recovery action in a woven glass fiber (GF) reinforced styrene based SMP. The model is validated using experimental investigations done with DMA Q800 analyser and a specially designed bending recovery tool where a slight deviation of (8%-16%) was achieved. The model findings showed significant reduction in recovery time of 25% and 41% when the fiber content increased from 20% to 25% and 30%, respectively. This makes the proposed model a valuable tool for engineers to assess the shape memory behavior. Experimental findings indicated that fiber reinforcement led to a significant enhancement in thermomechanical properties represented by 5oC increase in glass transition temperature and five orders of increase in storage modulus. Also, a remarkable improvement in shape recovery rate of up to 80% is obtained, however there is a slight reduction of (8% - 16%) in the shape fixity property.

In designing a flexible microfluidic-based pressure sensor, the microchannel plays an important role in maximizing the sensor's performance. Similarly, the material used for the sensor's membrane is crucial in achieving optimal performance. This study presents an analytical analysis and FEA simulation of the membrane and microchannel of the flexible pressure sensor, aimed at optimizing it design and material selection. Different types of materials, including two commonly used polymers, Polyimide (PI) and Polydimethylsiloxane (PDMS) were evaluated. Moreover, different designs of the microchannel, including single-channel, double-channel, and triple-channel, were analyzed. The applied pressure, width of the microchannel, and length of the microchannel were varied to study the normalized resistance of the microchannel and maximize the performance of the pressure sensor. The results showed that the triple-channel design produced the highest normalized resistance. To achieve maximum performance, it is found that using a membrane with a large area facing the applied pressure was optimal in terms of dimensions. In conclusion, optimizing the microchannel and membrane design and material selection is crucial in improving the overall performance of flexible microfluidic-based pressure sensors.

Unbonded steel-mesh-reinforced rubber bearings (USRBs) have been proposed as an alternative isolation bearing for small-to-medium-span highway bridges. It replaces the steel plate reinforcement of common unbonded laminated rubber bearings (ULNR) with special steel wire meshes, resulting in improved lateral properties and seismic performance. However, the impact of this novel steel wire mesh reinforcement on the ultimate compression capacity of USRB has not been studied. To this end, theoretical and experimental analysis of the ultimate compression capacity of USRBs were carried out. The closed-form analytical solution of the ultimate compression capacity of USRBs was derived from a simplified USRB model employing elasticity theory. A parametric study was conducted considering the geometric and material properties. Ultimate compression tests were conducted on 19 USRB specimens to further calibrate the analytical solution, considering the influence of the number of reinforcement layers. An efficient solution for USRBs’ ultimate compression capacity was obtained via multilinear regression of the calibrated analytical results. The efficient solution can simplify the estimation of USRBs’ ultimate compression capacity while maintaining the same accuracy as the calibrated solution. Based on the efficient solution, the design process of a USRB with a specific ultimate compression capacity was illustrated.

The internal hydroforming of large stainless-steel eggshells from a stepped preform is investigated in this paper. The nominal major and minor axes of the eggshell were 1537 and 1070 mm, respectively. The stepped preform was fabricated from thin-walled (1.9 mm thick) stainless-steel sheets and comprised twelve conical segments inscribed inside the target eggshell. The preform was then hydroformed, and its wall thickness and shape were measured. The yield load distribution and material hardening of the hydroforming process were investigated analytically. Nonlinear finite-element analyses were employed to further investigate hydroforming behaviors and the effect of weld lines on hydroforming. The experimental, numerical, and analytical results were consistent. The results confirm that, during the hydroforming process, considerable springback occurs for large eggshells, which greatly affects forming precision. However, this effect can be reduced by accounting for the strengthening effect of weld lines. [ABSTRACT FROM AUTHOR]

A known complication for mechanically loaded bone implants is the instability due to screw loosening, resulting in infection and the non-union of fractures. To investigate and eventually prevent such bone degradation, it is useful to know the stress state in the bone around the screw. Considering only in-plane loadings and simplifying the mandibular bone into an orthotropic laminated plate, the analysis was reduced to a two-dimensional pin-loaded plate problem. An analytic model, based on the complex stress analysis, was introduced to the bone biomechanics field to obtain the stress distributions around the screw hole in the bone. The dimensionless normalized stresses were found to be relatively insensitive to the locations of the screw hole over the mandible. Parametric analyses were carried out regarding the friction coefficient and load direction. It was found that the load direction had a negligible influence. On the contrary, the friction coefficient had a significant effect on the stress distributions. Whether the screw was well bonded or not thus played an important role. The proposed analytic model could potentially be used to study bone failure together with stress-based failure criteria. [ABSTRACT FROM AUTHOR]

Permanent magnet eddy current couplers (PMECCs) have the characteristics of contactless torque transmission, removal of torque ripple, smooth dynamic process, and adjustable speed, and can be used as couplings, dampers, brakes, and speed governors. Their applications in industry, vehicles, and energy fields are gradually expanding. At the same time, the requirements for the torque density and dynamic performance of PMECCs are increasing. Therefore, a large amount of research work has focused on the fast and accurate modeling, design, and optimization of PMECCs. This paper provides a survey on the development of PMECCs technology. The main topics include the structure and classification of PMECCs, modeling methods, loss and heat transfer analysis modeling, and optimization design. In addition, this paper shows the future trends of PMECCs research. All the highlighted insights and suggestions of this review will hopefully lead to increasing efforts toward the model's construction and the optimal design of PMECCs for future applications. [ABSTRACT FROM AUTHOR]

In this study, the nonlinear analytical analysis of a two-layer geometry made of functionally graded materials (FGMs) is examined. FGMs can be used in various engineering applications, such as building materials in civil engineering, due to the advantages of smoothly varying properties. The equations of stresses and displacements in the radial and circumferential directions (r, θ ) have been found by extracting the governing equations and defining them in the form of power-exponential functions. In the present paper, modulus of elasticity and heat conductivity coefficient (except for Poisson’s coefficient) are assumed to be expressed by power-exponential functions in radial and circumferential coordinates. The temperature distribution is also considered as a function of radius (r) and angle (θ). The analysis is implemented based on the theory of small elastic deformations and with the assumption of a very large length in plane strain mode. To analyze the governing equations, first, the heat transfer equations are obtained, and then the Navier’s equations are derived by combining the stress–strain, strain–displacement, and stress equilibrium equations. Then, the displacement equations and stress equations are obtained by solving the Navier’s equations. A direct method is presented to solve these equations analytically.

Tapered Plate girders are considered the best efficient choice in design of the industrial buildings and bridges with large-span. Openings in the web of plate girders are frequently required to give space for services, resulting in increased fabrication costs and a reduction in load-carrying capability. The aim of the present paper is to estimate the critical shear buckling of tapered plate girders containing a circular or square opening. Finite element simulations were performed on 176 steel beams with prismatic and tapered web containing two different shapes of openings (circular and square). The analysis considered the effects of tapering angle, hole size with respect to the average height of the web, aspect ratio, depth to thickness ratio and the boundary conditions between the web and flanges. The numerical results are used to estimate an analytical expression for the critical shear stress of prismatic and tapered web panels containing a circular or square opening. [ABSTRACT FROM AUTHOR]

In this study, the most modern Fiber-Reinforced Polymer (FRP) composites, Basalt Fiber-Reinforced Polymer (BFRP) bars, have been used to reinforce concrete columns as main longitudinal reinforcement bars, under the effect of both concentric and eccentric loading setup, 50 mm from Reinforced Concrete (R.C.) column center. Eight full-scale R.C. columns with longitudinal steel bars or BFRP bars have been tested. The spacing between the mild steel stirrups has been 200 mm. Some of the R.C. columns have been enhanced externally with BFRP wrapping sheets as strips with a width of 100 mm and at a spacing of 200 mm measured from the BFRP wrapping sheet's center and arranged between mild steel stirrups in order to minimize the free length of confinement to study the effect of BFRP wrapping sheets in enhancing of concrete column capacity. The test results have confirmed the significant enhancement in concrete confinement efficiency in BFRP R.C. columns, especially in the concentric case. An analytical study has been carried out to compare the design equations in different codes with each other. In addition, the obtained results yield a proposed design equation for the R.C. column with BFRP bars and strengthened externally with BFRP sheets. [ABSTRACT FROM AUTHOR]

Rotor-bearing systems often exhibit nonlinear behavior due to hydrodynamic effects and external forces. Finite element methods based on linear analysis are commonly used for rotor dynamic analyses, where nonlinear bearing/damping forces are linearized into equivalent stiffness and damping coefficients. However, this method may not accurately describe strongly nonlinear systems. Engineers use transient analysis and nonlinear models to improve rotor behavior analysis. This study investigates the effects of transient-thermal bending and vibration on a high-pressure steam turbine rotor using the finite element method. A scaled rotor-shaft was used to study thermal bending and vibrations caused by steam heat. The design of the shaft was based on an existing power station high-pressure turbine rotor. Numerical modal analyses were performed using ANSYS software to obtain a partial level of integrity between the numerical model and the analytical model. Natural frequencies were compared between the experimental, numerical, and analytical results, which showed good correlations.

The 3D point clouds obtained from the low-cost, remote, and precise SfM (Structure from Motion) technique allow the extraction and acquisition of discontinuities and their characteristics both manually, with the compass and virtual ruler of the Cloud Compare software, and automatically with the DSE (Discontinuity Set Extractor) program, which is faster, more accurate, and safe. Some control plans have been used, which basically consist of identifying one or several fractures and taking measurements on them manually and remotely. The difference between both types of measurements is around 5°, which we believe is reasonable since it is within the precision and repeatability of measurements with a geologist's compass. This work analyzes the stability of six slopes (five excavated and one natural) by applying five different analysis methodologies based on the rock mass classification system (SMR, RHRSmod, and Qslope), kinematic analysis, and analytical analysis (limit equilibrium). Their results were compared with what was observed in the field to identify the most appropriate analysis methodologies adjusted to reality. The necessary parameters for analyzing each of the slopes, such as orientation, quantity, spacing, and persistence of the discontinuities, were obtained from the automatic analysis. This type of analysis eliminates the subjectivity of the authors, although the findings are related and resemble those obtained manually. The main contribution of the article consists of the application of fast and low-cost techniques to the evaluation of slopes. It is a type of analysis that is in high demand today in many Andean countries, and this work aims to provide an answer. These methodologies suggested by scientific articles such as this one will later be integrated into some procedures and will be taken into account by technical reports. The results show that with the available information and by applying low-cost techniques, the SMR system is the methodology that presents the best results and adjusts better to the reality of the study area. Therefore, SMR is a necessary parameter to determine rockfall hazards through modified RHRS. [ABSTRACT FROM AUTHOR]

This paper deals with the analysis of leakage characteristics of the proportional directional valve. These characteristics distinguish a real directional valve from an ideal one. The ideal directional valve is characterized by zero leakage due to its perfect geometry. The investigated element is the three-position four-way proportional directional valve with zero spool lap and feedback from the spool position. The spool position is measured by the inductive position sensor and processed by external electronics. Internal leakage occurs due to axial and radial clearances between the spool and the sleeve. The magnitude of axial clearances that occur at throttle edges and their effect on the directional valve leakage is the subject of research. The blocked-line pressure sensitivity curve, the leakage flow curve and the center flow curve are determined by experiment. Individual characteristics are determined for different working fluid temperatures and different supply pressures. The flow through internal leaks in the center position of the valve spool is determined by analytical calculations. The flow through internal leaks is also simulated using the Ansys Fluent software. Subsequently, the geometry of the flow simulation model is modified to take into account manufacturing tolerances. From simulation results, the effect of the manufacturing tolerance magnitude on the internal leakage of the directional valve is evaluated. Finally, simulated dependencies are compared with experimentally determined characteristics. [ABSTRACT FROM AUTHOR]

The sand‐filled nodular pile (SFNP) foundation is newly proposed to improve the bearing capacity and accelerate consolidation settlement of foundations installed in soft clay soil. By filling sand while driving the nodular pile into the soft clay soil, the SFNP foundation provides an extra drainage path with the aid of the nodular segment, while maintaining the high modulus reinforcement body at the core of the composite foundation. The performance of the SFNP foundation is greatly influenced by its consolidation behaviour. This study develops a generalized model for the SFNP foundation, and a closed‐form solution is then established considering the smear and well resistance effects. The developed model and the associated analytical solution are employed to investigate the consolidation rate and load distribution of the SFNP foundation. Finally, the analytical solution is utilized to evaluate the performance of SFNP foundation for an expressway project located in Zhejiang, China. The predicted dissipation of the excess pore water pressure employing the developed analytical solution agreed well with measured response from the field test, which further confirmed the advantages of the SFNP foundation and the reliability of the developed solution. [ABSTRACT FROM AUTHOR]

The use of a magnetic adjustable speed drive is a popular choice in industrial settings due to its efficient operation, vibration isolation, low maintenance, and overload protection. Most conventional magnetic adjustable speed drives use various forms of the permanent magnets (PMs). Due to the PMs, this type of machine has continuous free-wheeling losses in the form of hysteresis and induced eddy currents. In recent years, the homopolar-type rotor has been widely used in high-speed machines, superconducting machines, and in the application of flywheel energy storage. This study proposes a new application of the homopolar-type rotor. A novel adjustable speed drive with a homopolar-type rotor (HTR-ASD), which has obvious advantages (no brush, no permanent magnet, and no mechanical flux regulation device), is designed and analyzed in this study. Its speed and torque can be adjusted only by adjusting the excitation current. Firstly, in this study, the structure, operation principles, and flux-modulated mechanism of the HTR-ASD are studied. The homopolar-type rotor has a special three-dimensional magnetic circuit structure with the same pole. The 3D-FEM is usually used to calculate its parameters, which is time consuming. In this study, an analytical method is developed to solve this issue. To analytically calculate the torque characteristics, the air gap magnetic flux density, and the winding inductance parameter, the equivalent circuit and the air gap permeance are researched to simplify the analysis. Then, the key parameters of the HTR-ASD are calculated. Finally, the performance of the HTR-ASD is comparatively studied using the analytical method and finite element method, and a comparison of the results is carried out. The comparison indicates that the analytical method is in good agreement with simulation results, and that it is very helpful for designing homopolar-type rotor machines. According to the analysis, the proposed adjustable speed drive displays a great performance in relation to the operating characteristics of a flexible mechanical speed drive. [ABSTRACT FROM AUTHOR]

The internal hydroforming of large stainless-steel eggshells from a stepped preform is investigated in this paper. The nominal major and minor axes of the eggshell were 1537 and 1070 mm, respectively. The stepped preform was fabricated from thin-walled (1.9 mm thick) stainless-steel sheets and comprised twelve conical segments inscribed inside the target eggshell. The preform was then hydroformed, and its wall thickness and shape were measured. The yield load distribution and material hardening of the hydroforming process were investigated analytically. Nonlinear finite-element analyses were employed to further investigate hydroforming behaviors and the effect of weld lines on hydroforming. The experimental, numerical, and analytical results were consistent. The results confirm that, during the hydroforming process, considerable springback occurs for large eggshells, which greatly affects forming precision. However, this effect can be reduced by accounting for the strengthening effect of weld lines.

Permanent magnet eddy current couplers (PMECCs) have the characteristics of contactless torque transmission, removal of torque ripple, smooth dynamic process, and adjustable speed, and can be used as couplings, dampers, brakes, and speed governors. Their applications in industry, vehicles, and energy fields are gradually expanding. At the same time, the requirements for the torque density and dynamic performance of PMECCs are increasing. Therefore, a large amount of research work has focused on the fast and accurate modeling, design, and optimization of PMECCs. This paper provides a survey on the development of PMECCs technology. The main topics include the structure and classification of PMECCs, modeling methods, loss and heat transfer analysis modeling, and optimization design. In addition, this paper shows the future trends of PMECCs research. All the highlighted insights and suggestions of this review will hopefully lead to increasing efforts toward the model’s construction and the optimal design of PMECCs for future applications.

A known complication for mechanically loaded bone implants is the instability due to screw loosening, resulting in infection and the non-union of fractures. To investigate and eventually prevent such bone degradation, it is useful to know the stress state in the bone around the screw. Considering only in-plane loadings and simplifying the mandibular bone into an orthotropic laminated plate, the analysis was reduced to a two-dimensional pin-loaded plate problem. An analytic model, based on the complex stress analysis, was introduced to the bone biomechanics field to obtain the stress distributions around the screw hole in the bone. The dimensionless normalized stresses were found to be relatively insensitive to the locations of the screw hole over the mandible. Parametric analyses were carried out regarding the friction coefficient and load direction. It was found that the load direction had a negligible influence. On the contrary, the friction coefficient had a significant effect on the stress distributions. Whether the screw was well bonded or not thus played an important role. The proposed analytic model could potentially be used to study bone failure together with stress-based failure criteria.

The methods available to predict the strain and tension of geogrid are regularly based on two-dimensional condition, however, the three-dimensional deformed shape of geogrid is seldom considered in the literature. This paper proposed an analytical method to calculate the settlement of reinforced piled embankment considering three-dimensional deformed geogrid, in which the arching effect, the bearing capacity of geogrid and subsoil were taken into account. Firstly, three-dimensional deformation formula of geogrid was derived. Then the load transfer mechanism in the reinforced piled embankment was analyzed, including deriving the vertical stress at the base of the embankment, the vertical stress acting on the geogrid and that taken by the subsoil for piles arranged in the square pattern and in triangle pattern. The proposed analytical method can calculate the maximum settlement at the surface of the subsoil directly, and then the vertical stress acting on the subsoil surface, as well as the distribution of vertical stress along the embankment height can be derived. Finally, the proposed analytical method was used to calculate the settlement of two field cases. The difference between the results calculated from the proposed analytical method and the measurements was 19.5% and 9.2%, respectively, which validated the proposed analytical method. [ABSTRACT FROM AUTHOR]

• The paper summarizes the measurement equipment used for experiments. • The paper summarizes a decade of research on experimental, analytical, semi-analytical, and numerical simulation methods. • The paper discusses the limitations and future directions of current methods. Composite stiffened panels, known for lightweight, high load-bearing efficiency, and low cost, are commonly used in aerospace structures. These panels are subjected to various loading conditions, including axial compression, shear, or combination, with buckling as a prevalent failure mode. Composite stiffened panels maintain some load-bearing capacity despite buckling, entering a post-buckling state. Researchers commonly employ experimental methods, analytical solutions, and numerical methods to investigate the buckling and post-buckling behavior of composite stiffened panels. Experimental studies highlight failure modes such as skin-stiffener debonding, interlaminar damage, and delamination under various conditions. Analytical methods provide computationally efficient solutions during the early design stages. Numerical methods, particularly finite element analysis (FEA), effectively predict critical buckling loads and failure mechanisms, facilitating design optimization and cost savings. This review synthesizes a decade of research into the buckling and post-buckling behaviors of composite stiffened panels, incorporating experimental, analytical, and numerical studies. Insights from these studies highlight the need for advanced predictive models and design methodologies that maximize the weight reduction and efficiency of composite stiffened panels in aerospace applications. [ABSTRACT FROM AUTHOR]

Energy consumption in the building sector poses a huge burden in terms of global energy and pollution. Recent advancements in building information modelling and simulating building energy performance (BEP) have provided opportunities for energy optimization. The use of building information modelling (BIM) also has increased significantly in the last decade based on the requirement to accommodate and manage data in buildings. By using the data, some building information modelling tools have developed the function of energy analysis. This paper aims to identify design parameters critical to BEP to assist architects in the initial stages of building design and to investigate their relationship. The outcomes of the prototype model's energy simulations were then used to construct multilinear regression models. For the rest of the independent building design variables, linear regression models are used to analyse the relationship between it and energy consumption. It was concluded that, in the same building conditions, diamond-shaped buildings have the highest energy consumption, while triangle-shaped buildings showed the most efficient energy performance through energy simulations for seven fundamental prototype building models based on Autodesk Kits, Green Building Studio (GBS) with a Doe-2 engine. In addition, the developed regression models are validated to within 10% error via a case study of the ABS building. At the end of this paper, recommendations are provided on energy optimisation for the initial stages of building design. The parametric analysis of design variables in this study contributed to the total energy consumption at the early phases of design and recommendations on energy optimization. [ABSTRACT FROM AUTHOR]

In the existing standards, there are still some insufficient considerations of the pile end soil and the mutual reinforcing effect between piles when computing the settlement of long-short-pile composite foundation. For fully considering the mutual reinforcing effect, the thin-ring cylinder shear model and the shear displacement method are adopted in this paper. Besides, the relationship between the settlement and axial force of the solid pile and the virtual soil pile is obtained in process by applying the virtual soil-pile model to considering the stress and deformation of pile end soil. It proposes an improvement of the interaction coefficient between the long and short piles and is applied to the analytical solution for the settlement of long-short-pile composite foundation. Compared with experiments, the error between results of two methods is only 4.65%, which indicates that the proposed method can accurately calculate the settlement of long-short-pile composite foundation. Meanwhile, the measured values are compared with the analytical and simulated values, and the results of three methods have good consistency, which further verifies the correctness and applicability of the analytical method in this paper. [ABSTRACT FROM AUTHOR]

In this research, the maximum stress, Hashin, Puck, LaRC03, and Northwestern University (NU) criteria are analyzed based literature data, analytical results obtained using a MATLAB program and numerical results obtained from an Abaqus finite-element model. The applicability and reliability of these failure criteria for predicting damage in thermoplastic laminates are evaluated based on analytical and numerical results. According to numerical results, the maximum stress criterion provided the most conservative prediction, but the Hashin and Northwestern University (NU) criteria gave reasonable and sensible outcomes at an acceptable running time. The Puck and LaRC03 criteria showed more accurate predictions, but at longer running times. [ABSTRACT FROM AUTHOR]

Wireless mesh networks are designed as an economical solution to provide high quality service for last-mile broadband Internet access. The paramount priority of these networks is the throughput maximization which is in conflict with a scarce bandwidth. Multicast is a technology that provides a good trade-off between maximizing the throughput and minimizing the bandwidth usage. This paper quantifies the reliability gain of combining classes for reliable multicast in the wireless mesh network. We define the delay as the performance metric for reliability. We then provide an analytical analysis to study the impact of group size, packet loss rate and depth of the multicast tree on the performance improvement achieved by combining classes. Our numerical results show that combining classes significantly reduces distribution delays, compared to the receiver-initiated class alone. The performance gains increase as the group size, the packet loss rate and the depth of the multicast tree increase, making the classes combination approach more scalable with respect to these parameters.

This paper presents an analysis of a permanent magnet synchronous machine (PMSM) with an unequal teeth width. The use of the concentrated nonoverlapping winding, also known as tooth-coil winding, has certain advantages. In addition, asymmetric features can be exploited by adopting this winding configuration to improve the machine performance. The procedure involves increasing the stator tooth width and, to the same extent, reducing the adjacent stator tooth width. In this paper, an analytical method was employed to predict and understand the back-EMF behavior, and a finite element analysis (FEA) was performed to verify the analytical method. Furthermore, a detailed study of the machine performance (electromagnetic torque, flux density, and losses) was carried out by the FEA. The machine was built and tested to validate the performance of the machine.

The 3D point clouds obtained from the low-cost, remote, and precise SfM (Structure from Motion) technique allow the extraction and acquisition of discontinuities and their characteristics both manually, with the compass and virtual ruler of the Cloud Compare software, and automatically with the DSE (Discontinuity Set Extractor) program, which is faster, more accurate, and safe. Some control plans have been used, which basically consist of identifying one or several fractures and taking measurements on them manually and remotely. The difference between both types of measurements is around 5°, which we believe is reasonable since it is within the precision and repeatability of measurements with a geologist’s compass. This work analyzes the stability of six slopes (five excavated and one natural) by applying five different analysis methodologies based on the rock mass classification system (SMR, RHRSmod, and Qslope), kinematic analysis, and analytical analysis (limit equilibrium). Their results were compared with what was observed in the field to identify the most appropriate analysis methodologies adjusted to reality. The necessary parameters for analyzing each of the slopes, such as orientation, quantity, spacing, and persistence of the discontinuities, were obtained from the automatic analysis. This type of analysis eliminates the subjectivity of the authors, although the findings are related and resemble those obtained manually. The main contribution of the article consists of the application of fast and low-cost techniques to the evaluation of slopes. It is a type of analysis that is in high demand today in many Andean countries, and this work aims to provide an answer. These methodologies suggested by scientific articles such as this one will later be integrated into some procedures and will be taken into account by technical reports. The results show that with the available information and by applying low-cost techniques, the SMR system is the methodology that presents the best results and adjusts better to the reality of the study area. Therefore, SMR is a necessary parameter to determine rockfall hazards through modified RHRS.