Valeri Bakardzhiev, Sabi Sabev, Konstantin Chukalov
Engineering parts have increasingly higher requirements for geometric accuracy and shape deviation. In 3D printing, optimal physical and mechanical properties and dimensional accuracy are often sought, as parts produced with this technology are increasingly used not only for prototypes but also for responsible technical products. This requires precise studies of 3D printing parameters of engineering filaments. Accuracy is how close the measured size is to the CAD model. Carbon fiber-reinforced polymers are characterized by high strength and stiffness. In this article, dimensional accuracy of 3D-printed parts made of carbon fiber-reinforced polyamide was studied. For this purpose, eight samples were produced in the shape of a rectangular prism with two types of through holes—hexagonal and round. The dimensional accuracy of the overall dimensions and the holes was studied. The data was processed statistically with the aim of building an adequate mathematical model that analytically synthesizes the expected dimensional accuracy for different combinations of the selected 3D-printed parameters.
Jacob Van Den Broek, Melinda Hodkiewicz, Adriano Polpo
Chutes, bins, and hoppers are critical assets in bulk commodity handling. Sacrificial wear liners are employed to protect these assets from abrasive wear. An essential maintenance challenge is optimising the timing of liner replacements. Traditionally, episodic human inspections have been in place, but now, real-time wireless IoT sensing systems that measure liner thickness are being used. We propose a novel approach to estimate the remaining useful chute liner life. Instead of linear extrapolation based on individual sensor wear rates (commonly used in industry), we leverage a Clustered Bayesian Hierarchical Modeling (BHM). Two models are developed: Model 1 (Cluster Exemplar) uses parameters from the closest cluster exemplar, while Model 2 (Spatial and Temporal BHM) incorporates data from the active sensor, with prior distribution informed by Model 1. Data are drawn from a single hopper with 88 sensors, 20 of which reached their end-of-life threshold. Both Model 1 and Model 2 outperform the industry regression approach, significantly reducing overprediction. Notably, Model 2 predicts remaining useful life within 95% credible intervals and identifies anomalous sensor performance. This innovative use of historical and adjacent sensor data enhances wear degradation prediction, contributing valuable insights to the literature.
Engineering machinery, tools, and implements, Systems engineering
This work aims to study the influences of nozzle temperature, layer thickness and raster angles on the mechanical properties of acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA) specimens fabricated by material extrusion 3D printing. Tensile tests were carried out in order to evaluate the mechanical properties of ABS and PLA specimens. The results showed that tensile strength decreased at a higher nozzle temperature for ABS, while an increase followed by a decrease in tensile strength occurred for PLA, with the maximum value obtained at 250 °C. Scanning electronic microscopy was used to analyze the surface fracture after tensile tests of specimens fabricated with different nozzle temperatures. Moreover, the highest tensile strength values for both ABS and PLA were achieved with a raster angle of [0°], the same direction as the applied tensile load. Additionally, a higher tensile strength was obtained for both ABS and PLA at a lower layer thickness. Based on these results, the process parameters used to manufacture a 3D object influence its mechanical properties.
This study aims to enhance safety within the Budapest tram network by developing methods to assess and manage tram drivers’ cognitive workload. While defensive driving reduces accident risk, it becomes less effective when drivers are mentally overloaded. There is currently no reliable method to objectively measure this workload, which this research aims to develop. Trams frequently interact with unpredictable road users, increasing the likelihood of sudden braking and related injuries. Using accident data, high-risk locations were identified, and cognitive workload was assessed via eye-tracking (blinks and fixations) in a tram simulator. Participants drove two predefined routes and responded to unexpected events as they would in real traffic. Results reveal a correlation between blink/fixation frequency and cognitive load, enabling the identification of mentally demanding locations. These insights support targeted interventions to reduce driver workload and enhance operational safety.
Reducing the ratio of box girders' span to their height reduces bending moments and makes them deep members that are controlled by shear behavior. The presence of horizontal curvature generates torsional moments and different deflection between the outer and inner web as a result of twisting. Two experimental specimens with the same dimensions were cast and tested, one straight and the other horizontally curved. The two specimens were numerically modeled using the ABAQUS software for the purpose of verifying the numerical model to study more parameters. The finite element analysis showed a good agreement with the experimental values with a difference of (98-99) %, (94-97)% and 103% of the experiment for ultimate loading, deflection and twisting angle, respectively. It also showed stress paths that match the experimental and theoretical results that explain the behavior of deep beams, such as the Strut and Tie method (STM). The effect of compressive strength, whole width, and the width of the bearing and supporting plates was studied. Results showed that increasing the concrete's compressive strength by about 40-120%, increased the load capacity and decreased its deflection by approximately 6-14% and 3-15%, respectively. The deep box section torsional resistance increased when its width was increased by approximately 17–50%, although this had no significantly affect on the load capacity level. A reduction of 17-33% in the width of the loading and supporting bearing plates caused a 6-16% drop in load capacity besides a notable decrease in stiffness.
Engineering machinery, tools, and implements, Mechanics of engineering. Applied mechanics
Various nano-photocatalysts have been used to decompose organic dyes. Sb<sub>2</sub>O<sub>3</sub> nanoparticles (NPs) have emerged as potential photocatalysts due to their redox potential, non-toxicity, long-term stability, and low cost. This work describes the fabrication of Sb<sub>2</sub>O<sub>3</sub> NPs via the solvothermal process. A field emission scanning electron microscopic (FE-SEM) analysis depicted the spherical shape of the NPs, and an energy-dispersive X-ray (EDAX) analysis confirmed the presence of oxygen (O) and antimony (Sb) in the synthesized NPs. XRD (X-ray diffraction) patterns were recorded to measure the size and phase of the NPs. The sample was found with an alpha phase of antimony oxide indicating high purity. The Scherrer equation was used to calculate the size of the NPs, which was found to be approximately 20.89 nm. The photocatalytic potential was tested against methylene blue (MB) dye. The NPs showed a 60% degradation of the dye in 60 min. The dye was found to be adsorbed on the Sb<sub>2</sub>O<sub>3</sub> nanoball surface and degradation was associated with the generation of reactive oxygen species (ROS).
The appeal of a car’s exterior often captures a customer’s initial attention, but the interior ultimately seals the deal, creating a lasting connection between the customer and car. The interior quality plays a significant role in shaping the overall impression of a vehicle. Interior surfaces with tactile and visual qualities contribute to customer experience. Traditionally, automotive manufacturers have relied on natural grains, leather, and occasional geometric patterns to enhance the aesthetic appeal and tactile experiences of interiors. This study presents a novel approach to texture pattern design for automotive interiors. This method uses city maps from diverse locations as sources to create unique textural patterns. The process begins by capturing high-resolution images of city maps, selecting segments based on tessellation potential, applying abstraction and correction, cleaning the image to eliminate unwanted elements, and generating a 2D black-and-white pattern that simulates the texture when applied to the CAD surfaces of the interior components. This approach offers a unique alternative to the conventional practice of selecting texture patterns from the existing sources. This enables automotive designers to create signature texture patterns that differentiate between brands in a competitive market.
Gianluca Cadelano, Nicola Stecchetti, Paolo Bison
et al.
The presence of moisture in masonry is crucial because it causes and exacerbates various deterioration mechanisms, such as crystallization of salts, mechanical stresses due to freeze–thaw cycles, biological degradation, etc. The assessment of the water content is critical for cultural heritage buildings; thus, on-site non-invasive techniques have been proposed over time. An innovative active thermographic procedure is proposed and tested in a laboratory to assess the amount of moisture via a non-destructive approach. The methodology is based on heating a brick specimen together with a reference sample which has known thermophysical properties. Evaporation is inhibited by an impermeable film applied to the samples. The trends in the surface temperatures of both materials are recorded using infrared thermography and compared with each other: the calculation of the thermal inertia of the wetted material is retrieved from the comparison of the temperature trends in both samples. The water content value is thus determined from the thermal inertia of the sample.
This review aims to study in detail the characterization of winery wastewater (WW), the problems caused by its release into the environment without proper treatment, and the processes that can be applied for its treatment. Several works showed that the WW has a composition based on soluble sugars, organic acids, alcohols, and high molecular weight compounds. Among these, the phenolic compounds are considered to be very toxic, due to the difficulty of degradation by microorganisms, and also because they represent toxicity to humans and animals. To solve this issue, biologic treatments are considered to be cheaper and more effective for biodegradable WW, with the possibility to store biogas with anaerobic treatments. To complement biological treatments, physical-chemical processes based on adsorption, coagulation-flocculation-decantation (CFD), and advanced oxidation processes (AOPs) are also discussed in this review.
Some areas of the Lanzhou-Xinjiang Railway are accompanied by strong crosswinds all the year. The lateral force it generates pose a threat to the safe operation of railway freight trains. This paper conducts a numerical simulation study on three freight trains under five crosswind angles by using CFD method in order to aiming at the relationship between the crosswind angle and the aerodynamic force. The SIMPLE algorithm is used to solve the Reynolds-averaged N-S equation and the SST k-ω model is used for the turbulence model. The research results include the variation of the aerodynamic force on the three freight trains with the crosswind angle and the variation of the aerodynamic force on each train. In addition, this paper discusses the pressure and flow field distribution around the freight train. The results of this paper provide a reference for the safe operation of Lan-Xin Railway.
This paper introduced the smelting process of Inconel600 nickel-ferrochrome alloy by medium frequency induction furnace. The smelting, forging, rolling and drawing process parameters of the alloy are determined by this study. By using nitrogen and oxygen analyzer, direct reading spectrometer, OEM, electronic probe and electronic universal material testing machine, the chemical composition, gas content, inclusions, internal microstructure, mechanical properties and fracture morphology of the trial-produced products were analyzed. The results show that the Inconel600 nickel-ferrochrome product meets the national standard and the comprehensive performance of the product is good.
This paper introduces the design requirements and design methods of structural materials in the process of aircraft model design, and introduces the shortcomings of traditional methods in this kind of structural design. Based on this, a full elastic model design method combining metal and composite materials is established. This method has the characteristics of accurate and fast design and simple structure. In order to verify the effectiveness of this method, this paper lists two related aircraft model structure design schemes, and introduces the design process and design results. The experimental results show that the above method can effectively complete the aircraft full elastic model design, the model design is accurate, and can meet the needs of aircraft simulation.
Cavitation and embolization of plants accompanied by conduit vibration due to intermolecular adhesion of water or the adhesion of the conduit wall are signs of water stress. Ultrasonic acoustic emission (UAEs) was used to detect plant air pockets and embolic events transmitted by vibration. The UAEs could be detected in ultrasonic frequency between 100K Hz and 1 MHz. In general, the spatial location of UAEs sources for the influence of signal spatial distribution are greater than the UAEs signal wave shapes to the time. Using the electro-acoustic similarity theory, UAEs can be seen as the step voltage sources, the medium as the load, the water column rupture model (UAEs mutation model) in the plant conduit can be established by the analog circuit method. Without considering the change of plant stems medium density and ultrasonic velocity, the ultrasonic energy is proportional to square of the ultrasonic pressure. According to plant water stress relationships between ultrasonic energy release and ultrasonic energy, the UAEs ring counts or signal strength can be used to indicate the range and extent of plant conduits embolism, which can establish the model of UAEs and physiology by statistical laws. Studies have shown that the UAEs waves transmit in the plant fiber, signal attenuation in the fiber is a function of cell tissue hardness, and the approximate attenuation values are 1 dB/cm, 10 dB/cm and 20 dB/cm in hardwood, softwood and herbaceous plants, respectively.
The management system consists of a sensor waveform conversion system, a fault handling detection system, and a switching execution system. In this paper, the integration circuit is used for waveform transformation, the elimination of the offset voltage of the amplification circuit, and the integration compensation in feedback control. And we collect data from each state of the system under test, and use the redundant fault-tolerant system to manage and warn the system status to verify the effectiveness of the model. Combined with the waveform generation circuit and the waveform transformation circuit, the output of the signal generator is connected to the input of the integration circuit. The function of the waveform transformation system is to transform one waveform into another waveform, which can convert the square wave into a triangular wave. The redundant fault tolerance model proved to be effective on this management system, that is, the redundant fault-tolerant system has good generalization and can be implemented in the aerospace scene.
A novel green controlled synthesis method is proposed in this paper. Mesoporous alumina was prepared by using sodium aluminate extracted from red mud as an aluminum source. The influence mechanism of temperature, template agent and sodium aluminate concentration on MA properties was studied systematically. The results show that the prepared mesoporous γ-alumina has a good catalytic activity of short-range arrangement, medium acidity, narrow pore size distribution, thermal stability and hydrothermal stability. This economical and green synthesis method can also be used to prepare other mesoporous or porous materials.
As an important component in electronic equipment, the reliability of electrical connectors determines the life of the entire electronic equipment. Vibration is one of the main factors affecting the reliability of electrical connectors, and the contact pressure of connectors is an important indicator of the reliability of connectors. In this paper, ANSYS simulation is used to study the contact pressure of electrical connectors under static and different vibration conditions. The research results show that the contact pressure becomes smaller under the vibration condition than under the static condition. The increase of the vibration amplitude has little effect on the contact pressure; the increase of the vibration frequency has a great influence on the contact pressure. With the increase of the vibration frequency, the minimum value of the contact pressure decreases.
This study describes a method for probabilistically predicting the acoustic properties of porous sound-absorbing materials. Porous materials consist of complex microstructures, and homogenization methods can predict their dynamic properties. However, it is difficult to consider the randomness of the microstructure as in actual porous materials. This randomness affects the acoustic characteristics of the sound-absorbing material. Therefore, we propose a method to consider randomness in the homogenization unit cell and calculate the probability distribution of the sound absorption characteristics. The balance of computational cost with prediction accuracy is essential in predicting stochastic behavior in the multiscale simulation. Thus, we propose a Bayesian approach to achieve both computational cost and prediction accuracy. Random variables are assumed to be the microstructure shape parameters. The product of these probability density functions and the sound absorption coefficient is integrated to calculate the probability distribution of the sound absorption coefficient. The function of the sound absorption coefficient is approximated to calculate this integral by Gaussian process regression. This integral value follows a gauss distribution, and its variance is evaluated as the correctness of the approximation of the integral value. We define this variance as an acquisition function and adaptively obtain additional sampling points where it is minimized. Then, the sound absorption coefficient is recalculated with multiscale simulation at additional points to update the approximate model. Repeating these processes allows the probability distribution to be approximated with reasonable accuracy.
Mechanical engineering and machinery, Engineering machinery, tools, and implements
Sergiy Kotenko, Svitlana Ilchenko, Valeriia Kasianova
et al.
The purpose of this study was mathematical model development for assessing the cost of losses from risks in the maritime transportation of goods that are dynamic in nature, and developing a methodical approach to the dynamic costs assessment for each of the risks separately and integral costs for all risks and ensuring the fulfillment of the requirement to anticipate the insurance cost changes over the rate of change of the transportation integral risk (or its stage). The risks factor analysis in water transport, their classification and determination of the type and nature of their impact on sea transportation of goods were carried out. The groups of risk factors that lead to emergency situations for water transport in Ukraine were studied by comparing the data of 2019 and 2021 and determining their share in the total number of accidents before the start of the active phase of hostilities in Ukraine; the rates of their change were analyzed. This made it possible to develop a systematic assessment algorithm for the dependence of the expected and actual value of losses on risks and to create a mathematical approach to risks forecasting as a factor influencing the cost of expenses. As a result of the study, a methodical approach to forecasting the cost of losses from risks was formed for each of their types. However, the main attention was paid to the identification and assessment of dynamic risks, the impact of which has an absorbing nature relative to all others in their totality. Such risks in the waters of the Black and Azov seas today mainly include risks associated with the conduct of military operations, including such operations that go against international legal norms.
Engineering machinery, tools, and implements, Technological innovations. Automation
This paper discusses a multiscale stochastic stress analysis of a particle reinforced composite material with a successive approximation based on the local sensitivity analysis of microscopic stresses with respect to a random location variation of particles. A microscopic geometrical random variation will have a significant influence on the microscopic stress fields in a heterogeneous material, and probabilistic analysis of the stresses should be encouraged for estimation of probabilistic properties of the stresses for more reliable structural design. Further, a more complicated microstructure reflecting an actual material considering wider analysis region, for example, including a larger number of inclusions in composite materials will be required for a practical application. This numerical analysis will be very expensive, and therefore a successive local sensitivity analysis-based approximate multiscale stochastic analysis method has been proposed for unidirectional fiber reinforced composite material. In this research, this approach is extended to a three-dimensional problem, and effectiveness of the approach for the multiscale stochastic analysis of a particle reinforced composite material is investigated. In this paper, the problem setting and outline of the methodology are provided, and the effectiveness and accuracy of the presented method are discussed with the numerical results.
Mechanical engineering and machinery, Engineering machinery, tools, and implements