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Nowadays, finite element tyre models are often used to perform vehicle NVH (noise, vibration, harshness) simulations. To account for the specific operating conditions, a road surface must be properly included in the model. This paper deals with a methodology to experimentally evaluate and process road irregularity measurements, so as to generate a road surface input. These surfaces are used to simulate the tyre/road interaction at the footprint, which is modelled as a contact surface in finite element tyre models. For this reason, a linear profile of the road surface is not suitable for these simulations and the whole surface must be considered. Starting from the measurements taken through a test equipment specifically designed to carry laser sensors and scan road profiles, the Power Spectral Density (PSD) of a specific track is estimated and then interpolated considering piecewise functions. Finally, a model to generate a road surface starting from the measured PSD is developed, discussed and validated. [ABSTRACT FROM AUTHOR]

Geotextiles are excellent anti-filtration materials commonly used in the field of water conservancy engineering; however, the factors affecting the water permeability performance of geotextiles under stressed states during operation have not been fully identified. To investigate the effect of unidirectional stretching on the water permeability of geotextiles, a unidirectional rheological head infiltration test was conducted on the geotextiles using a self-developed test apparatus. In addition, the water permeability of geotextiles with different thicknesses and tensile states was calculated using a set of water permeability calculation methods based on the nonlaminar flow state of geotextiles. The results showed that the water permeability of the W120 geotextile samples initially decreased and then increased under warp stretching and gradually increased under weft stretching. However, the water permeability of the W200 geotextile samples initially decreased and then increased under both warp and weft stretching. Therefore, the thickness of the geotextile affected its permeability properties. [ABSTRACT FROM AUTHOR]

In this paper, an electro-hydraulic servo resonance technology is proposed to meet the loading requirements of a high-frequency sound fatigue test for large tonnage. First of all, we analyze the static and dynamic loading structure of electro-hydraulic servo vibration and establish the vibration equation of the system. Additionally, the modal and vibration characteristics of the system are analyzed by simulation, which verified the feasibility of the proposed electro-hydraulic servo resonant loading technology. Finally, the influence of various factors such as sample stiffness, lead screw stiffness, class II spring stiffness, class II weight mass, lower beam mass, and upper beam mass on the natural frequency and amplification coefficient of the system is analyzed. In this paper, a new technology is proposed to provide theoretical support for the research and development of large-tonnage high-frequency noise fatigue testing equipment. [ABSTRACT FROM AUTHOR]

Epoxy resins inherently have low resistance to scratching. To increase the scratch resistance of epoxy resins, reinforcing solid lubricants into the resin is an option. For this purpose, in this study, polytetrafluoroethylene (PTFE) and graphite were reinforced in two different epoxy resins (rigid and toughened) at different reinforcement ratios (5, 10, and 15 wt%). The effects of solid lubricant reinforcement on the scratch behavior of rigid and toughened epoxy resins were examined both experimentally and statistically. Scratch tests were performed throughout a distance of 10 mm using a test apparatus under a load of 15 N and a scratch speed of 30 mm/min. Following the scratch tests, the COF (Coefficient of Friction) values, scratch hardness, scratch width, and depth of all samples were determined and compared to neat epoxy for each resin. In general, it has been determined that solid lubricant reinforcement at higher reinforcement ratios has a positive effect on the COF value (15 wt%). In the case of 15 wt% graphite reinforced rigid and toughened epoxy, a decrease of 15.90% and 17.77%, respectively, was obtained in the COF value compared to the neat epoxy. After the scratch tests, statistical analysis was performed according to RSM to support the experimental results, and ANOVA tables were obtained. Highlights: Epoxy adhesives exhibit low scratch resistance.Examining the impact of PTFE and graphite reinforcement on scratch behavior.Two types of epoxy and varied reinforcement ratios (5, 10, and 15 wt%) were studied.Solid lubricant reinforcement to epoxy positively affected scratch behavior. [ABSTRACT FROM AUTHOR]

The relationship between the soil water characteristic curve (SWCC) and the mechanical behavior of unsaturated soil is imperative and has been well investigated. However, the correlation between elastic wave velocity along the wetting and drying paths of SWCC is largely unknown due to the nonavailability of a standard experimental setup for such a purpose. An ordinary triaxial apparatus has been modified for laboratory assessment of SWCCs under different Ko stresses, along with the measurement of shear and compression wave velocities in due course. The main aim of the study is to draw SWCC, wave velocity characteristic curve (WVCC), and a Poisson's ratio characteristic curve (PRCC) and to establish the phenomenon that these curves possess hysteresis. The Poisson's ratio was obtained indirectly by measuring Vp and Vs. Three soil samples with relative densities of 85%, 56%, and 39% were prepared and placed in a modified triaxial test apparatus under wetting and drying cycles. The test results showed that the newly developed apparatus is accurately capable of measuring SWCC. Owing to the similarity in the shape of wave velocity and Poisson's ratio, response to SWCC, WVCC, and PRCC are drawn. The phenomenon of stress history and the effective stress of the soil affected the behavior during wetting and drying paths. [ABSTRACT FROM AUTHOR]

Background: To evaluate the stability of jointed rock masses subjected to dynamic disturbance, laboratory dynamic shear test on rock joint is necessary. Developing dynamic shear test equipment for rock joint is currently a pressing issue. Objective: To address this issue, a new apparatus is developed to reproduce the shear-slip process of rock joint subjected to dynamic disturbance under various initial stress state. Methods: The disturbance load, which has a dominant frequency close to that of seismic waves, is generated by an electromagnetic-driven disturbance generator, and its amplitude and duration can be accurately controlled in a stable manner. The initial normal and shear stresses can be applied in the shear test under dynamic disturbance using servo-controlled loading unit, which facilitates the simulation of the real stress state of rock joint. Results: The shear tests under dynamic disturbance show that when an initial shear stress is applied to rock joint, an additional deformation stage of stress recovering can also trigger a slip displacement, which contributes to the destabilization of jointed rock masses. With increasing initial shear stress, the dynamic slip displacement, stress drop and post-disturbing deformation increase. The feasibility of the apparatus to conduct quasi-static direct shear tests with both the constant normal loading (CNL) and constant normal stiffness (CNS) boundaries is also verified. Conclusions: Test results demonstrate that using the new apparatus, shear-slip properties of rock joint subjected to dynamic disturbance can be tested in various initial stress states. [ABSTRACT FROM AUTHOR]

Lost motion is utilized to characterize the transmission accuracy of gear reducers and is commonly evaluated through the hysteresis curve method. In examinations of lost motion for large and medium-sized reducers, the default practice is the application of the equal torque gradient loading method. Nonetheless, for small-sized reducers, this approach is deemed inappropriate due to the constraints of the servo motor loading resolution. This study reveals that employing a larger unit torque for equal torque gradient loading can modify the shape of the hysteresis curve and influence the assessment of lost motion. As a result, this paper introduces two innovative loading techniques, namely equal position gradient loading and uniform speed loading, to address the limitations of equal torque gradient loading and reduce the demands on testing equipment. Subsequent experiments validate the issues associated with equal torque gradient loading, confirm the effectiveness of the two new loading techniques, and yield more comprehensive hysteresis curves. It is important to note that all three loading methods are influenced by the loading rate, but the two novel methods can mitigate the effects of loading rate dependency. [ABSTRACT FROM AUTHOR]

This study describes a novel laboratory test apparatus for investigating the axial interaction between pipeline and soil. Contrary to the majority of existing pipe–soil shear rigs, the proposed apparatus applies a relative pipe–soil shear displacement through driving a soil box below an axially restrained pipe segment, which is instrumented to measure the pipe settlement and the axial resistance at the pipe–soil contact surface. Through axial shear tests of polypropylene pipe segment on sand, this study explores the effect of vertical loads, soil types, and densities on the resulting axial resistance and estimates the interface stress evolution. The coefficients of axial resistance obtained from large-scale pipe–soil shear tests are compared to those obtained via planar element interface shear tests with consideration of the wedging effect. Their consistency suggests that under the low stress levels investigated in this study, the effect of both pipeline curvature and settlement on the resultant data are minor. The agreement provides validation for the novel apparatus to generate high-quality data under controlled conditions for future studies. The findings of this study will also potentially help reduce the uncertainties around subsea pipeline design when linking the interface shear behaviour at element scale to large-scale pipe–soil interaction. [ABSTRACT FROM AUTHOR]

Conducting and repeating large-scale cyclic load tests are challenging, as these tests are time-consuming, labour-intensive and demanding advanced laboratory facilities. As a screening test method to select the geosynthetic-reinforced pavement configurations for further investigations on a large scale, small-scale cyclic load tests by using laboratory experimental setups with lesser dimensions, therefore, are a preferred starting point for any cyclic loading tests. This paper presents the outcomes of a series of small-scale cyclic loading tests, evaluating the rutting performance of unreinforced and geogrid-reinforced unpaved roads using a circular mould with a 305 mm-diameter and 520 mm height. The test apparatus was capable of conducting a greater number of tests and provided better statistical confidence with relatively minimal effort compared to larger box tests reported in the literature. These cyclic loading tests were conducted on a granular base of varying thicknesses, placing the selected geogrid-reinforcement types (i.e. composite or biaxial) within the granular layer and/or at the base-subgrade interface. Test results show geogrid reinforcement placed at the base–subgrade interface can significantly reduce permanent-vertical deformation when the granular base thickness is relatively thin. Results also show biaxial geogrid in the middle of the granular base performs well in reducing rut depth compared with composite or biaxial geogrid placed at the base–subgrade interface. The potential benefits of geogrid reinforcement diminish with an increase in base thickness because the reinforcement acts as a rigid boundary, and failure would occur above the top layer reinforcement. Better rut resistance in unpaved granular pavements was exhibited first by double reinforcement, then biaxial geogrid at the middle of the granular base, then composite geogrid at the middle of the granular base, followed by composite geogrid at the base–subgrade interface and then biaxial geogrid at the base–subgrade interface. The findings of this experimental study are beneficial for pavement researchers in designing and planning large-scale cyclic loading laboratory or field tests for future research by optimising the number of tests, thus reducing the required amount of materials, cost and effort. [ABSTRACT FROM AUTHOR]

It is easy to find electromagnetic contactors in modern electromechanical devices owing to their advantages, which encompass a simple structure, ease of use, and low cost. However, these devices also have inherent drawbacks, including heat dissipation, contact erosion, and inefficient power consumption during long-term operation. This has sparked interest in contact soft-landing, which aims to reduce issues like contact bounces, contact welding, and arcing. This paper presents the development of a testing apparatus for investigating the electromagnetic dynamics of contactors or mechanical relays, aimed at developing an open-loop model-based controller for contact soft-landing. Theoretical equations based on physical theorems are derived to describe the behavior of the electromagnetic coil under varying factors. Additionally, a pilot study was conducted using the proposed testing apparatus to explore the relationship between heat dissipation, flowing current, air gap, and the Lorentz force produced by exposing ferromagnetic material to the magnetic field surrounding the electromagnetic coil. The experimental and simulation results showed good fitting, with a normalized root mean squared error ranging from 2.5% to 4.5% for various scenarios. Notably, it was found that the flowing current passing through the electromagnetic coil can be controlled by changing the duty cycle of the pulse width modulation signal driving the conductivity of the MOSFET. However, the results suggest that a modulation frequency greater than 5 kHz is not suitable for driving the electromagnetic coil. [ABSTRACT FROM AUTHOR]

The design of segmental geosynthetic mechanically stabilized walls with masonry block facing is often governed by the loads that develop at the connection between the facing and geosynthetic. Yet the current understanding of the mechanisms involved in the mobilization of such connection loads is, at best, incomplete. The testing apparatus developed as part of this study facilitates simulating the transference of stresses at the face and evaluating the facing connection loads in geosynthetic-reinforced soil walls. This study assesses the connection loads between a geogrid reinforcement connected frictionally to modular concrete blocks. A comprehensive instrumentation program was implemented to capture lateral earth pressures, geosynthetic strains and loads acting at the geogrid-block connection in a geosynthetic-reinforced unit cell subjected to incremental surcharge stages. Results indicate that conventional calculations, based on earth pressure theory, may underestimate the facing connection loads, mainly when the connection loads are triggered by the differential settlement of the backfill relative to the block facing. When this mechanism dominates the mobilization at the connection, reinforcement loads increase as the differential settlement increases, developing down-drag forces at the connection between the geogrid and modular blocks. • Facing connection loads should not be understood only as a result of earth pressures. • Relative settlements between block facing wall and backfill soil cause a down-drag deformation of the reinforcement. • Down-drag deformation of the reinforcement induces significant connection loads. • The magnitude of connection loads increases with the magnitude of down-drag deformation. • Facing connection loads can be greater than the maximum reinforcement tensile load. [ABSTRACT FROM AUTHOR]

The evaluation of hydrogen sorption properties in materials is crucial for their widespread applications. However, existing volumetric apparatuses often suffer from low accuracy and efficiency due to inadequate calibration techniques, temperature gradients, and limited automation. To address these limitations, a Temperature-Variable Cycle (TVC) Sieverts apparatus has been developed. Besides conventional tests, the device is capable of efficiently performing TVC tests, such as TVC Pressure-Composition-Temperature (PCT) isotherm and kinetics, through the integration of RS485 serial communication and automatic dosing techniques. The instrument's component selection and configuration were described in detail. Furthermore, novel methods for volume calibration and anti-thermal gradient were presented, where a continuous function was proposed to overcome temperature gradients across the entire range of test temperatures. Finally, a series of tests were conducted using La 0.5 Ce 0.5 Ni 4 Co alloy and Mg material as benchmark materials to validate the setup and methods. The accuracy of volumes and the feasibility of the methods were confirmed through null PCT tests and data comparisons of PCT with kinetic of La 0.5 Ce 0.5 Ni 4 Co alloy, respectively. By employing these methods, the accuracy of null tests is improved by nearly tenfold. The efficiency and robustness of the unit were demonstrated through Temperature-Programmed Desorption/Absorption (TPD/TPA), TVC PCT, and TVC kinetics tests on MgH 2 powder. The results produced by the TVC system align well with the reliable data in literature. [Display omitted] • An ultra-efficient and automatically TVC Sieverts apparatus has been developed. • The unit can obtain multiple curves at distinct temperatures within a single test. • A practical and accurate online volume calibration method was proposed. • A novel method of anti-thermal gradient for continuous temperature was presented. [ABSTRACT FROM AUTHOR]

Minicomposite, as the elementary scale of the full-scale ceramic matrix composites (CMCs), has been commonly considered as the appropriate specimen type for basic research on environmental behavior of CMCs due to its simple structure, low fabrication cost and mature modeling foundation. However, its size is too small relative to the full-scale CMCs, resulting in the existing environmental performance testing equipment developed for macrocomposites not matching it in all respects. In order to fill this gap, a compact environmental performance testing apparatus, which consists mainly of a two-zone furnace, gas humidifier, control system and a pair of quartz tubes and high temperature specimen grips, has been designed and built here. Creep test of SiC fiber at elevated temperatures from 800 to 1100 °C with water vapor and oxidation test of SiC/SiC minicomposite at 1316 °C in stress-free wet oxygen environment were carried out respectively to verify the accuracy and reliability of the rig. With the apparatus, the environmental degradation mechanism of CMCs can be quantitatively analyzed, which lays a foundation for the service life prediction and environmental performance optimization of CMCs. [ABSTRACT FROM AUTHOR]

The mechanical properties of the stent graft are important factors influencing the outcome of TEVAR treatment and the occurrence of postoperative complications. The aim of this study is to improve and design a mechanical performance testing equipment for thoracic aortic stent grafts. The mechanical performance testing equipment consists of a radial force testing equipment of the stent graft designed by the wire compression grip method and a dynamic straightening force testing device with stable and controllable test conditions and continuously variable test angles. By constructing the testing equipment to physically measure the stent specimen, the experimental results reflect the trend of change and the simulation results are basically consistent, i.e. the mechanical properties of the thoracic aortic stent designed in this study is feasible and the measured data are valid. The testing equipment can provide the basis and reference direction for the quality testing of stent graft products, optimisation of mechanical properties of stent grafts and R&D innovation. [ABSTRACT FROM AUTHOR]

The indicators of dynamic qualities that ensure the traffic safety, as well as the permissible impact on the railway track, with the obligatory fulfillment of which the railway rolling stock can be used in the transportation process, are presented in this article. The purpose of this work was to carry out the complex dynamic (running), and the impact on the railway track, tests of the rolling stock, during which simultaneous registration of dynamic processes on the railway rolling stock, and in the elements of the superstructure of the track, is carried out, as well as in elements of turnouts. Dynamic tests were carried out on the track switches from the minimum speed to the maximum possible speed of 50 km/h by the TE33A diesel locomotive during the freight traffic. Meeting the requirement of reproducibility of test conditions and having a typical design of the track structure on wooden or reinforced concrete sleepers. [ABSTRACT FROM AUTHOR]

The sedimentation, consolidation and desiccation behaviour of sub-aerially deposited tailings in tailings storage facilities, despite occurring simultaneously and being essential to maximise tailings dry density and dewatering efficiency, are usually analysed in laboratories using distinctive testing equipment, which is unable to reveal their interactions. A large instrumented column was constructed to test the three processes of tailings in a single apparatus, capable of monitoring the changes in the hydrological parameters of coal tailings with depth and surface settlement under natural weather conditions. The column was initially filled with coal tailings slurry and exposed to natural weather for two years, during which five wetting–drying periods were identified. The monitored results indicate that exposing the slurry tailings for one month would lead to the formation of an unsaturated tailings layer with a thickness of 150 mm, likely representing the optimised tailings deposition cycle and thickness, respectively, under the given tailings characteristics and semi-arid climates. Settlement mainly occurred after major rainfall events due to the collapse of cracks and cavities formed during the preceding desiccation. The maximum thickness of the unsaturated tailings increased over the first four periods as the predominant desiccation and settlement strengthened the evaporative capillary forces, despite it decreasing greatly in the last period due to insufficient desiccation. An empirical model was proposed to consecutively estimate the surface moisture content of deformable tailings and validated by achieving a good agreement in the water mass estimated by two methods during wetting–drying cycles. [ABSTRACT FROM AUTHOR]

Objectives: Determining the accuracy of cycloplegic refractive error measurements made with the Spot Vision Screener (SVS, Welch Allyn Inc, Skaneateles Falls, NY, USA) is important for refractive assessment of uncooperative patients during optometric examinations. This study compared cycloplegic refractive errors measured by SVS and tabletop autorefractometer to cycloplegic retinoscopy in children. Materials and Methods: Eighty-eight eyes of 44 subjects were examined in the study. Refractive error measurements were obtained under cycloplegia using retinoscopy, SVS, and Nidek ARK-530 tabletop autorefractometer (ARK-530, Nidek, Japan). Spherical and cylindrical values, spherical equivalents (SE), and Jackson cross-cylinder values at axes of 0° (J0) and 45° (J45) were recorded. Correlations between methods were analyzed using intraclass correlation coefficient (ICC) and Bland-Altman analysis. Results: The mean age was 7 years (range: 6 months-17 years). Sixteen (36%) of the subjects were female and 28 (64%) were male. For SE there was excellent agreement between retinoscopy and SVS (ICC: 0.924) and between retinoscopy and tabletop autorefractometer (ICC: 0.995). While there was a moderate correlation between retinoscopy and SVS for cylindrical values (ICC: 0.686), excellent correlation was detected between retinoscopy and autorefractometer (ICC: 0.966). J0 and J45 cross- cylinder power values were not correlated between retinoscopy and SVS (ICC: 0.472) or retinoscopy and tabletop autorefractometer (ICC: 0.442). Retinoscopy was correlated with both SVS and tabletop autorefractometer for all parameters within ±1.96 standard deviations in Bland-Altman analysis. Conclusion: Cycloplegic retinoscopy is the gold standard for refractive error measurement in the pediatric population. However, it requires time and experienced professionals. This study revealed moderate to good agreement between SVS and retinoscopy, with better agreement in spherical errors than cylindrical errors. Although the SVS is intended for screening programs, it may also be useful in the pediatric eye office to estimate spherical refractive error in uncooperative patients. [ABSTRACT FROM AUTHOR]

This paper presents test results from a study on the locking performance of jack bolt nuts with and without added secondary locking. A Junker-type test apparatus is used to apply dynamic transverse force loading to induce loosening. The test data reveal there are two mechanisms of loosening for jack bolt nuts, namely slip of the nut body and slip of the jack bolts. Furthermore, the data show the dominant mechanism of loosening in jack bolt nuts is nut body slip. Since the only currently available option for secondary locking for these types of fasteners is holes in the jack bolts heads for lockwire, additional methods for secondary locking for both mechanisms of loosening are developed and tested. For the test parameters used in this study, it is found that even without any secondary locking, loosening occurs only at relatively low preload levels. The effect of introducing secondary locking to only the jack bolts is a modest decrease in the rate of loosening. The effect of adding secondary locking to only the main nut body is a significant decrease in the rate of loosening. Adding mechanical or adhesive secondary locking to the main nut body and mechanical locking to the jack bolts eliminates loosening even at low preload levels. [ABSTRACT FROM AUTHOR]

To examine the disparity in deformation behavior and mechanical qualities between anchor cables with C-shaped tubes and regular anchor cables under shear conditions. The double-sided shear tests of free-section anchor cables and anchor cables with C-shaped tubes were conducted utilizing the indoor large-scale double-shear test equipment with varying pretension loads. The indoor double-shear tests indicate that the inclusion of the C-shaped tube alters the stress distribution of the anchor cables inside the anchor cables with C-shaped tubes and mitigates the impact of stress concentration. Moreover, it facilitates the transition of the anchor cable's failure mode from a mix of tensile and shear breaking to mainly tensile breakage. In addition, ABAQUS finite element analysis software was used to establish a double shear test model of the anchor cable with C-shaped tube to accurately simulate the interaction and stress distribution among the anchor cable, C-shaped tube, and concrete block in the double shear test. The findings of the simulation results reveal that the numerical model can adequately depict the evolution of the stress distribution in the prestressed anchored structure and the damage of the concrete block with increasing shear displacement. The relational equation for the yield state of the anchor cable with C-shaped tube under combined tensile and shear loads is found by integrating the experimental and simulation data, the static beam theory, and the concept of minimal potential energy. [ABSTRACT FROM AUTHOR]

This study focuses on how to define an Analytical Target Profile (ATP) which is intended for use in practice and on facilitating the selection of in vitro release test (IVRT) technology for diclofenac sodium topical hydrogel and cream. The implementation involves incorporating the new draft guidelines of the International Council for Harmonisation (ICH Q14) and USP (United States Pharmacopeia) Chapter 1220. Four IVRT apparatuses were compared (USP Apparatus II with immersion cell, USP Apparatus IV with semisolid adapter, static vertical diffusion cell, and a new, in-house-developed flow-through diffusion cell) with the help of the ATP. Performance characteristics such as accuracy, precision, cumulative amount released at the end of the IVRT experiment, and robustness were investigated. We found that the best apparatus for developing IVRT quality control (QC) tests in both cases was USP II with an immersion cell. All four different IVRT apparatuses were compared with each other and with the data found in the literature. [ABSTRACT FROM AUTHOR]

An electric pump-fed cycle can enable the electrical control of pump revolutions and rapidly vary the propellant flow rate. This paper proposes the pump control method as a flow control system of an electric pump-fed cycle. In order to evaluate the applicability of the designed flow control system, the test equipment that simulates an electric pump-fed cycle was constructed, including the Li-ion battery power system and communication instruments. The designed PID controller demonstrated rapid flow stabilization and robustness compared to the system without a controller. Meanwhile, under the initial pressurized condition in the run tank that simulated an engine start-up sequence, the controller response delay occurred was more than 500 ms. In addition, the dynamic loads, such as the water hammer effects and overshoot, were identified. The start-up sequence of an EP cycle was adjusted to alleviate those issues. Consequently, the supply stabilizing time and overshoot were adjusted to 400 ms and 1.7 %, respectively. This study can be the first step in utilizing an electric pump-fed cycle for the thrust control technology in the upper stage of a mission. • An electric pump-fed cycle has a simple system with an electric motor and battery system replacing a gas generator and turbine of a gas-generator cycle. • An electric pump-fed cycle can be used as a throttleable and restartable rocket engine technology, providing a rapid response enabled by the quick propellant feeding through an electrical signal control. • The pump control system with PID controller shortened the flow stabilizing in the experiments compared to the flow control system without the PID controller. • By adjusting the electric pump-fed cycle start-up sequence, it can effectively mitigate the water hammer and shorten the stabilizing time. [ABSTRACT FROM AUTHOR]

In this paper, eight shear tests were carried out utilising a double shear with infilled shear interfaces after determining an appropriate experimental design and modified testing scheme. For this, two rock bolts, 20 and 30 tonnes, were tested with modified double shear testing apparatus at different pretension loads. The infilled test scheme was conducted with 5 mm thick sandy clay infilled shear interfaces. A 40 MPa small aggregate concrete was used for all samples to simulate the host rock. Based on the shear profiles, it was found that all samples followed a three-part failure profile consisting of elastic, strain softening, and failure regions. The results of double shear tests revealed that the 20 tonne rock bolt saw a significant overall decrease of approximately 30% in its failure displacement response as opposed to the 30 tonne samples, which saw a 6% increase. Also, it was concluded that the 30 tonne samples outperformed the 20 tonne rock bolts by up to 30%, irrespective of initial pretension settings. Comparing the physical failure characteristics of the samples found that both the 20 and 30 tonne samples exhibited the same response to increased pretension. As the pretension increased, the angle experienced at the hinge point also increased incrementally. [ABSTRACT FROM AUTHOR]

In this study, gearbox radiated noise was successfully reduced through housing shape optimization. First, dynamic and structural–acoustic coupled analysis models of an agricultural UTV gearbox were developed. Then, the test equipment was configured to match that of the simulation model, and a test was conducted. The analysis and test results showed errors within 0.1 dB for vibration and 0.2 dB(A) for noise, indicating that the models were reliable. The housing design was then optimized using topology optimization based on the developed structural–acoustic coupling analysis model. The sound pressure level around the housing was used as an objective function for topology optimization. The optimal distribution of materials for the housing was also derived to reduce the radiated noise. Lastly, the housing rib was designed based on the optimization result, and an improvement in the radiated noise by approximately 2.43 dB(A) was confirmed in the operation area. [ABSTRACT FROM AUTHOR]

In this study, gearbox radiated noise was successfully reduced through housing shape optimization. First, dynamic and structural–acoustic coupled analysis models of an agricultural UTV gearbox were developed. Then, the test equipment was configured to match that of the simulation model, and a test was conducted. The analysis and test results showed errors within 0.1 dB for vibration and 0.2 dB(A) for noise, indicating that the models were reliable. The housing design was then optimized using topology optimization based on the developed structural–acoustic coupling analysis model. The sound pressure level around the housing was used as an objective function for topology optimization. The optimal distribution of materials for the housing was also derived to reduce the radiated noise. Lastly, the housing rib was designed based on the optimization result, and an improvement in the radiated noise by approximately 2.43 dB(A) was confirmed in the operation area. [ABSTRACT FROM AUTHOR]

Studies on the iodine-sulfur (IS) thermochemical cycle for hydrogen production has been carried out since about 2005 by the Institute of Nuclear and New Energy Technology, Tsinghua University, China. The HI decomposition occupies the important position of hydrogen generation in the IS cycle. In this paper, the HI-100 test apparatus with a H 2 production rate of 100 L/h was constructed and the HI decomposition was tested. First, the process and components for HI decomposition were designed. Then, the key components, including the feed tank, evaporator, gas heater, adiabatic reactor, condenser, and gas-liquid separator were made of industrial materials. After building this apparatus, the sealing test, heating water test, and HI decomposition have been conducted. The stable hydrogen production operation of more than 100 L/h had been achieved for 5 h, the maximum hydrogen production reached approximately 130 L/h, and the hydroiodic acid decomposition rate maintained about 22 %. The test results provide the design and experimental guidance for further amplification of HI decomposition for hydrogen production by the IS cycle. • The HI-100 test apparatus with the H 2 production rate of 100 NL/h was constructed. • An HI decomposition test for iodine-sulfur hydrogen production cycle was carried out. • The stable hydrogen production operation of above 100 L/h was achieved for 5 h. • The maximum hydrogen production rate reached about 130 L/h in HI-100 apparatus. • The hydroiodic acid decomposition rate maintained about 22 %. [ABSTRACT FROM AUTHOR]

Volatile organic compounds (VOCs) are the primary pollutant emitted by chemical laboratories, causing significant damage to the environment and posing a serious threat to human health. In this study, an industrial‐scale photocatalytic device was constructed for the removal of VOCs. The effectiveness of the photocatalytic device in removing gases such as ethyl acetate, dichloromethane, petroleum ether, and formaldehyde was investigated. The effects of gas flow rate, inlet concentration, temperature, and relative humidity on photocatalytic purification efficiency were revealed, which laid an important foundation for the further development of the industrial‐scale photocatalytic device. [ABSTRACT FROM AUTHOR]

(1) Background: Mandibular fractures are common, with the condylar process being a frequent site of injury, accounting for 25–45% of cases. This research aims to assess the mechanical suitability of various plates for high-neck condyle fractures. (2) Methods: Polyurethane models mimicking high-neck condyle fractures were utilized in this study. Sixteen distinct plate designs, constructed from titanium sheets, were tested. The figures underwent force assessments on a durability testing apparatus, and the relationship between used force and fracture movement was documented. (3) Results: For high-neck breaking, the two straight plates emerged as the most effective, aligning with established osteosynthesis standards. The second-best plate exhibited nearly half the strength of the gold standard. (4) Conclusions: In response to the aim of this study, considering the mechanical aspects, the double plain plate stands out as the optimal choice for osteosynthesis in cases of high-neck fractures of the mandibular condylar process. In addition, the authors propose the Mechanical Excellence Factor (MEF) as a superior metric for appraising a plate's mechanical force, surpassing the conventional Plate Design Factor (PDF). [ABSTRACT FROM AUTHOR]

Purpose: Radio frequency (RF) technology relies on the electromagnetic properties of the materials used, which includes their complex permittivities and loss tangents. To measure these properties, techniques for material characterization such as the transmission/reflection method are used in conjunction with conversion techniques to calculate these values from scattering parameters. Unfortunately, these techniques rely on relatively expensive rectangular waveguide adaptors and components, especially if testing over large frequency ranges. This paper aims to overcome this challenge by developing a more affordable test equipment solution based on additively manufactured waveguide sections. Design/methodology/approach: To evaluate the effectiveness of using additively manufactured waveguides to perform electromagnetic characterization with the transmission/reflection method, samples of PLA Tough with varying infill percentages and samples made from several Formlabs photopolymer resins are fabricated and analyzed. Findings: Results show that the method yielded permittivity and loss tangent values for the measured materials that generally agree with those found in the literature, supporting its credibility. Originality/value: The accessibility of this measurement technique will ideally allow for more electromagnetic material characterization to occur and expand the possible use of additive manufacturing in future RF designs. This work also provides characterization of several Formlabs photopolymer resins, which have not been widely analyzed in the current literature. [ABSTRACT FROM AUTHOR]

In view of the characteristics of a domestic concentrator s nickel flotation process, including unstable ore quality, large fluctuation of concentrate grade and unsatisfactory recovery rate. Combined with the current situation of incomplete testing equipment) long testing cycles, and high costs in the flotation production site; an intelligent control system for flotation process based on grade prediction model was designed. After the system was put into operation the stability of foam flow rate was significantly improved and the fluctuation of concentrate grade was significantly reduced, which proved the practicability of the system. [ABSTRACT FROM AUTHOR]

The resistance of rubber materials to different solvents and compression set need to be studied in order to determine the proper conditions of use and storage. In this research, we will study the effect of nanographene oxide (GO) as a filler substitution on the swelling characteristics and compression set of ethylene-propylene-diene monomer (EPDM) rubber/styrene-butadiene rubber (SBR) composites. The nanographene oxide was varied based on the amount (0, 2, 4, 6, 8 and 10 phr with and without modification). The EPDM/SBR composites were made using a two-roll mill and vulcanized using a hydraulic press. Furthermore, the composites were tested for resistance to immersion (swelling) according to ASTM D-471 using aromatic, aliphatic, and chlorinated solvents. The compression set testing is carried out according to ASTM D-395 with a compression test apparatus. From the research it is known that modified GO (mGO) can be a suitable filler substitution for EPDM/SBR composites. The 10 phr mGO is the most suitable filler substitution to increase swelling resistance and compression set for EPDM/SBR composites. [ABSTRACT FROM AUTHOR]

Virtual cycling engagement has seen a significant increase in the last decade, with a recognizable surge in 2020 due to the pandemic. To ensure a fair competition field, a testing apparatus was designed to test direct-drive bicycle smart trainers from various manufacturers. Smart trainers were tested for error on two main metrics: power measurement error and resistance error. Given that the integrity of virtual racing relies upon accurate power readings sent from the smart trainer to a cloud-based competition software, discrepancies in these metrics are most likely to affect the outcome of an event. The testing apparatus used a motor in place of a human rider to control the repeatability and capability of the testing system. Power measurements consisting of a torque and rotational velocity sensor were connected to the motor output to determine the precise power delivered to a smart trainer. The known input power was compared to the power reported by the smart trainer as transmitted over the ANT+ wireless protocol and compared across the testing metrics. An electromagnetic brake system was incorporated to characterize the transmission losses from the motor to the smart trainer, enabling the accurate determination of the actual power input into the smart trainers. The testing procedure covered each virtual gradient ranging from − 8 to 15% at every power level between 100 and 800 watts. The power reading error of smart trainers ranged from ≈ 0 to > 16%, and the resistance error ranged from < 1% to over 100%. These large errors show how critical the homologation of smart trainers is for fair competition. [ABSTRACT FROM AUTHOR]

• Counter-rotating Archimedean screws enable locomotion across challenging terrains. • Only a few terramechanics models for screws have been published and have limitations. • We present a novel testing apparatus to perform scroll terramechanics experiments. • Hardware tests show system will be useful for future terramechanics model development. Modeling the force interaction between a wheel and the ground is necessary when evaluating the effectiveness of a vehicle's mobility on challenging terrain. Soft soils with low bearing strength are a particularly difficult medium for wheeled vehicles. Helical scrolls have shown promise as an alternative to wheels which can work across a range of terrains, warranting a detailed terramechanics study to model their capabilities. Most of the existing terramechanics literature is limited to wheels and often employs an apparatus to study single wheels in a fixed geometry. This paper describes the design and implementation of a novel apparatus capable of housing a range of scroll geometries and configurations. The apparatus is comprised of a soil container, carriage to drive the scroll in two operating configurations, and a surrounding frame that enables both vertical and horizontal motions of the carriage. The carriage is outfitted with a drive system and instrumentation to measure the sinkage, stress, and drawbar pull values required for a terramechanics characterization. Initial stress-sinkage curves for three different scroll configurations align with expected results and provide a proof of concept that the proposed apparatus can successfully measure differing geometric parameters and can be used for further terramechanics characterizations. [ABSTRACT FROM AUTHOR]

• Experiments measured soil stress with single-wheel testing apparatus in soil bin. • Dynamic contact length impacts stress equations and soil mechanical properties. • Stress can be calculated under tire using function based on load and tire contact. • Mathematical equation followed trend of experimental data to estimate stress. The interaction between soil and tire is a complex phenomenon influenced by various factors, such as soil properties, vertical load on the wheel, and tire characteristics. However, estimating stress at the tire-soil interface is a challenging task due to the unpredictable nature of soil. Existing models for investigating the wheel-soil interaction are based on soil mechanical parameters, which are highly variable and require significant time and resources to measure accurately. In contrast, the amount of wheel sinkage into the soil can be measured in real-time and is derived from the mechanical properties of the soil. Therefore, there is a need to establish a relationship between stress and wheel characteristics such as dynamic contact length and tire sinkage in soil. To address this issue, this study introduces an analytical method to estimate the dynamic contact surface between the tire and soil. A mathematical model is then proposed to estimate stress, assuming the contact surface and variable pressure at the interface between the soil and tire. The stress model is validated through experimental tests conducted at three different vertical load levels and four different wheel traffic levels in the soil bin, repeated three times. [ABSTRACT FROM AUTHOR]

Little is known about how patients perceive diagnostic uncertainty. We sought to understand how patients and care partners perceive uncertainty in an emergency or urgent care setting, where making a final diagnosis is often not possible. We administered a survey to a nationally representative panel on patient-reported diagnostic excellence in an emergency department or urgent care setting. The survey included items specific to perceived diagnostic excellence, visit characteristics, and demographics. We analyzed responses to two open-ended questions among those who reported uncertainty in the explanation they were given. Themes were identified using an inductive approach, and compared by whether respondents agreed or disagreed the explanation they were given was true. Of the 1,116 respondents, 106 (10 %) reported that the care team was not certain in the explanation of their health problem. Five themes were identified in the open-ended responses: poor communication (73 %), uncertainty made transparent (10 %), incorrect information provided (9 %), inadequate testing equipment (4 %), and unable to determine (4 %). Of the respondents who reported uncertainty, 21 % (n=22/106) reported the explanation of their problem given was not true. The findings of this analysis suggest that the majority of patients and their care partners do not equate uncertainty with a wrong explanation of their health problem, and that poor communication was the most commonly cited reason for perceived uncertainty. [ABSTRACT FROM AUTHOR]

In order to reduce the labor intensity and improve the efficiency of pruning, this study designed a multi-section luffing apple pruning equipment suitable for apple orchards in hilly and mountainous areas of China. In the essay, the structure and working principle of the equipment are expounded, the cutter was analyzed, and the parameters were determined. Using the self-made test bench to simulate the field experiment, this study selected the ratio of cutting speed to feeding speed and feeding speed as the influencing factors and took the cut-off rate, cutting efficiency and cutting power as the objectives to carry out single factor experiment and quadratic regression orthogonal experiment. The test results show that the cutting power increases with the increase of ratio of cutting speed to feeding speed, and the cut-off rate and cutting efficiency first increase and then decrease. As the feeding speed increases, the cutting efficiency and power increase, and the cut-off rate decreases. When the cutoff rate was greater than 80%, the optimal combination of operating parameters was the feeding speed of 0.55 m/s and ratio of cutting speed to feeding speed of 1.29. Under this combination, the cut-off rate was 84.9%, the cutting efficiency was 13.1, and the cutting power was 175.7 W. The error between the predicted target value of the model and the average measured target value was less than 7%, so the test results are reliable. According to the obtained optimal operating parameters, the actual cutting experiment of the pruning equipment in the field was carried out, and the cutting rate was 96.3%, which meet the design requirements. This study can also meet the needs of mechanized pruning of fruit trees with different crown shapes, improve the applicability of pruning equipment, and provide support for the development of mechanized pruning equipment in China. [ABSTRACT FROM AUTHOR]

Accidental leakage of high-pressure CO 2 is not only a safety hazard, but also may have a great negative impact on the operating efficiency of some circulating systems. To analyze the accident hazards and improve the ability to predict the transient release flow behavior of high-pressure CO 2 , a set of small pipeline leakage test equipment was built. The changes of near-field pressure, temperature, and jet structure under different upstream pressure (6–12 MPa), temperature (280–300 K) and orifice diameter (5 mm, 10 mm, 20 mm, 40 mm) were analyzed. Secondly, as a supplement to the experiment, the near-field CO 2 gas phase distribution and critical mass flow were studied by numerical model. The results show that the near field pressure peak is negatively correlated with the initial upstream pressure, but positively correlated with the release diameter. In addition, the increase of upstream initial pressure and release diameter will lead to the increase of radial development range of near-field jet cloud. Based on the numerical results, an empirical correlation of critical mass flow based on upstream initial conditions and RHP is established. The error between the experimental data and the predicted value within the range of the correlation is within ± 18%. The research data and results can help to enhance the understanding of the rapid release characteristics of high-pressure CO 2 in the near field region and provide a basis for the study of CO 2 diffusion in the far field region and the leakage risk assessment. [ABSTRACT FROM AUTHOR]

Naraha Center for Remote Control Technology Development was established for the development and demonstration of remote control equipment and apparatus to promote the decommissioning of the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Company Holdings, Inc. The center has been in operation since 2016. The mission of the center is to contribute to the decommissioning of the Fukushima Daiichi Nuclear Power Station and the reconstruction of Fukushima Prefecture. This report describes the center's full-scale mock-up test facility, component test equipment for the development of remote control equipment and apparatus, and virtual reality systems and their utilization for the realization of the mission. [ABSTRACT FROM AUTHOR]

REEs play a pivotal role in the manufacturing of numerous industrial, defense, consumer, and aviation-related gadgets. As many primary sources of REEs are either exhausted or depleted, coal can be a good secondary source of REEs in the near future. The traditional thermochemical processes to extract REEs are expensive and detrimental to the environment, and thus exploration of more environment friendly and sustainable recovery methods are of the utmost necessity at the present time. In this study, we present in-depth investigation of REEs extraction from the coal samples from the Sohagpur coalfield, Madhya Pradesh. We conducted multiple experiments mainly focusing on rotational movement with the help of a laboratory shaker, magnetic stirrer with hot plate, and a flocculator jar test apparatus in the presence of acidic solutions. Our study highlights that the flocculator jar test apparatus exhibits the maximum recovery of REEs (Ce- 95%, Nd- 83%, La- 82%, Eu- 82%, Pr- 76%, Sm- 74%, Gd- 69%, and Tb- 69%) from coal in the presence of 2 M HNO3. This technique of REEs recovery from coal is easy to use, effective, has little environmental impact, and can be applied on an industrial scale with only minor adjustments to the machinery. [ABSTRACT FROM AUTHOR]

When designing subperiosteal implants, mechanical testing of the implant and abutment is inevitable. Subperiosteal implants and their abutments are medical devices made to order, so each implant requires a separate design, since each patient has a different bone surface, for which the implant must be designed. For the mechanical testing of subperiosteal implants, a new test apparatus was constructed, on which mechanical simulations were carried out, the subperiosteal implants were tested together with their abutments. In addition to the finite element analysis simulation, the test apparatus can also be used to determine how much force is generated by the chewing force on the subperiosteal implant and its abutment as a result of the chewing mechanism. [ABSTRACT FROM AUTHOR]

The method of scanning contact potentiometry (SCP) was investigated in factory conditions, and the functional capabilities of the electrical nondestructive testing (NDT) method to detect structural heterogeneities and technological defects were demonstrated directly in the process of reactor equipment production. [ABSTRACT FROM AUTHOR]

Since in the field of research concerning liquefaction phenomenon, the largest database exists for triaxial tests, this type of apparatus was selected as the most relevant. Available data concerning laboratory research on liquefaction tests for identification of undrained response of sand indicated that the results are very sensitive to even smallest incorrectness in the testing procedure. Besides, due to a complex nature of liquefaction phenomenon, it was considered prudent to undertake some efforts directed to increase the objectivity of tests. Therefore, before commencement of the actual test program for investigation of undrained response of soil, it is necessary to carry out some preparatory experimental work consisting of application of indispensable modification necessary for enhancement of a quality of a triaxial test. The paper presents the key issues pertaining to the implementation of the experiment. Significance of these modifications for desired characteristics is emphasized. Relevance of some upgrading of the equipment for liquefaction tests is exemplified. [ABSTRACT FROM AUTHOR]

Objective The effect of mechanical properties of hydrate decomposition on reservoir stability was studied by multi-stage depressurization of gas hydrate under the action of different types of decomposition promoters. Methods The effect evaluation and law analysis of rock mechanics stability of hydrate sediment reservoir are carried out by using multiple factors such as different effective confining pressures, different decomposition agents and their concentrations, soaking time, and through multi-level depressurization decomposition. Results With the pressure drops and decomposition, hydrate saturation, shear strength and elastic modulus decrease gradually, and methane hydrate sediments show brittle failure. Conclusions The higher the concentration of decomposition agent is, the greater the influence on hydrate mechanics is caused. The higher the injection concentration is, the longer the soak time is, the lower the hydrate strength is, and the more obvious the effect of the decomposition agent on reducing the hydrate strength is. Alcohol decomposition agent (ethylene glycol) is easier to weaken the strength of hydrate samples and to reduce reservoir stability than salt decomposition agent (CaCl2) during hydrate production. [ABSTRACT FROM AUTHOR]

In marine applications, the scaled wind turbine model (SWTM) based aerodynamic testing apparatus is regarded as one of the most effective approaches to predict the aerodynamic performance of offshore floating wind turbines (OFWTs). To fully disclose the aerodynamics of OFWTs, such kind of apparatus should meet two design requirements: (1) accurate representation of the aerodynamic characteristics of reference wind turbines and (2) reasonable reproduction of the environmental factors from real-world wind-wave-coupled field. Baring with these considerations, the authors propose a cost-effective SWTM-based aerodynamic testing apparatus, which consists of an innovative SWTM, a wind-wave simulator (WWS) and a data acquisition and analyses system. The proposed SWTM is featured by a double-deck tower, which satisfies the requirements of similarity in geometry, stiffness and mass, and a set of redesigned blades. The proposed WWS is capable of simulating both the time-varying inflow wind and the wave-induced platform motions through a wind field generator and a motion simulator. Based on the developed apparatus, a series of aerodynamic tests are conducted to validate the effectiveness of the apparatus design. In addition, the coupling effects of inflow wind and platform motions on the aerodynamics of OFWT are further revealed through experimental tests. [ABSTRACT FROM AUTHOR]

In this paper, after determining an appropriate experimental design and testing scheme to test the shear performance suitably, the impacts of pretension and shear interfaces on fibreglass rock bolts were investigated. For this purpose, at the first stage, the double shear testing apparatus was modified to address the issues and shortcomings of the established testing methodology. Then, 20-tonne and 30-tonne rock bolts were tested with pretension loads of 0 kN, 10 kN, 15 kN, and 20 kN for each test scheme. For this, a 40 MPa small aggregate concrete was used for all samples to simulate the host rock. The grout used to anchor the rock bolts was mixed to the product's recommended guidelines to ensure close resemblance to field mixtures. To maintain consistency, all samples were manufactured with the same concrete and grout recipes. The results of double shear tests revealed that increasing the pretension also increased the confining pressures at the shear interfaces for clean joints. This, in turn, reduced the damage propagating from the bolt at the shear interface and decreased the hinge point bending. The results can be applied for further analytical and numerical studies, which could utilise for a better understanding of the shear behaviour of fibreglass rock bolts. Highlights: Two types of fibreglass rock bolts, the 20-tonne and 30-tonne rock bolts, were tested utilising the modified double-shear apparatus. The double-shear testing apparatus was modified to address the issues and shortcomings of the established testing methodology. The double shear performance profiles of the bolts could be described by three regions categorised as the elastic, strain-softening, and failure regions. Increasing the pretension of each rock bolt type resulted in a reduction in the severity of the recorded shear force dip. The increased pretension yielded less physical damage to the rock bolt propagating away from the shear plane. [ABSTRACT FROM AUTHOR]