Changes In Rules Research Articles

A comprehensive investigation into the mechanism of belt wear influencing heat partition ratio through force and temperature analysis during robotic belt grinding Inconel 718

Robotic belt grinding serves as a pivotal method for achieving precision machining in re-manufacturing of aeroengine components made of Inconel 718. During grinding, the heat partition ratio (Rw) significantly influences the quality of the machined workpiece, which is affected by many grinding parameters. Belt wear, which is an unavoidable phenomenon during grinding, can substantially impact Rw. However, previous research works have paid little attention to the effect of belt wear. In this study, the variation of Rw with belt wear is comprehensively investigated by observing heat generation and heat input. Firstly, the belt wear behaviors are qualitatively and quantitatively described. Then, the impact mechanism of belt wear on force-related characteristics is analyzed to clarify the change rule of heat generation. Following this, the variations of temperature-related characteristics during belt wear are examined. Meanwhile, the heat input is obtained by the combination of finite element analysis and the inverse heat method. Finally, a rapid growth followed by a gradual decrease pattern of Rw with belt wear is derived and analyzed. The findings in this paper lay a crucial foundation for controlling the grinding quality during robotic belt grinding Inconel 718.

Rat anterior cingulate neurons responsive to rule or strategy changes are modulated by the hippocampal theta rhythm and sharp-wave ripples.

To better understand neural processing during adaptive learning of stimulus-response-reward contingencies, we recorded synchrony of neuronal activity in anterior cingulate cortex (ACC) and hippocampal rhythms in male rats acquiring and switching between spatial and visual discrimination tasks in a Y-maze. ACC population activity as well as single unit activity shifted shortly after task rule changes or just before the rats adopted different task strategies. Hippocampal theta oscillations (associated with memory encoding) modulated an elevated proportion of rule-change responsive neurons (70%), but other neurons that were correlated with strategy-change, strategy value and reward-rate were not. However, hippocampal sharp wave-ripples modulated significantly higher proportions of rule-change, strategy-change and reward-rate responsive cells during post-session sleep but not pre-session sleep. This suggests an underestimated mechanism for hippocampal mismatch and contextual signals to facilitate ACC to detect contingency changes for cognitive flexibility, a function that is attenuated after it is damaged.

Research on interface precision control strategy for additive manufacturing of coplanar sand laying with multi-material composite sand mold

Compared with the additive manufacturing of single sand material, it is more difficult to form multi-material composite sand mold. The paper focuses on the influence of sand laying process for the multi-material composite sand mold, explores the change rules in the quality of different curing agent content of composite sand mold, realizes the high quality and high precision sand laying of multi-material sand, and expands the application of composite sand mold in complex structure and high performance products.

Multi-scale damage characterisation of semi-flexible pavements under freeze-thaw cycles

This study aims to investigate the failure mechanism of semi-flexible pavements (SFP) under freeze-thaw conditions and to provide theoretical support for optimizing the material properties. By simulating the freeze-thaw damage process of SFP in actual service scenarios and combining various experimental methods, the strength characteristics and microstructural change rules of SFP in the freeze-thaw process are systematically analyzed. The study used freeze-thaw tests to simulate the real environment, combined with indirect tensile tests (IDT) and three-point bending tests to evaluate the mechanical properties of SFP. To further investigate the failure mechanism, scanning electron microscopy (SEM) was used to observe the interfacial changes between asphalt and early-strength sulphoaluminate cement (JGM301). Additionally, CT scanning was used to capture the structural changes of SFP during freeze-thaw cycles. The results showed that freeze-thaw cycles significantly and negatively affected the split tensile strength of SFP. SEM observations revealed that cracks appeared at the asphalt-cement interface (ITZ), the cement-SBS bond weakened, and the structure of the cement itself became loose. CT revealed structural changes such as cracking at the interface of the two-phase material, creation of new voids, and linkage of old voids during freeze-thawing of the SFP. In summary, the reduction in adhesion at the cement-asphalt interface and the frost swelling of JGM301 are the main reasons for the damage of SFP in freeze-thaw cycles. This study provides an important basis for an in-depth understanding of the freeze-thaw damage mechanism of SFP and optimization of its performance.

Effects of energy input modes on energy efficiency and berry quality in continuous microwave drying

To elucidate the effects of energy input modes on energy efficiency and berry quality in continuous microwave drying, four energy input modes with variational working ways of magnetrons were investigated by using numerical simulation and bench experiments in a continuous microwave dryer. Energy efficiency was divided into absorption and conversion efficiency to study the change rule of drying process, and the retention rate of anthocyanins of berry’s representative nutrition ingredient was studied considering both of the temperature and its uniformity. Results indicate that the energy input modes affect the absorption efficiency by changing the distribution uniformity of electric field of material layer, and the conversion efficiency by altering the matching degree between the energy allocation and drying characteristics of berry, which are both determined by the ways of working magnetrons of different energy input modes. The conversion efficiency has a greater influence on the final energy efficiency, so the energy input mode should be paid attention to the provision of microwave energy by selecting proper way of working magnetrons according to the drying characteristics. The effect of temperature uniformity on anthocyanin degradation is more obvious with average temperature increasing gradually, where better uniformity of electric field strength should be provided to guarantee the quality of dried berry by adjusting the energy input mode. The research results provide significant insights to optimize the energy input mode of taking into account both the energy efficiency and dried quality of material.

Thermomechanical buckling and vibration of composite sandwich doubly curved shells with carbon nanotube‐reinforced face layers

AbstractIn this paper, the thermomechanical buckling and vibration analysis are investigated for carbon nanotube‐reinforced composite sandwich doubly curved shells (CNCSDS) under the action of both thermal loads and in‐plane compressive loads. Based on the von‐Karman non‐linear kinematic relations, First Order Shear Theory, and Hamilton's principle, the vibration and stability equations for CNCSDS under thermomechanical loads are deduced. For obtaining the critical thermomechanical buckling load and vibration frequency, an exact method is adopted. Subsequently, the results are validated by comparing with the finding in published literature and simulation results. At last, the influence of system parameters on critical thermomechanical buckling load and vibration frequency is studied and displayed graphically. Meanwhile, some new results about thermomechanical buckling and vibration analysis of CNCSDS are proposed for the first time.Highlights Thermomechanical buckling and vibration of carbon nanotube‐reinforced composite sandwich doubly curved shells was studied. Vibration and stability equations under thermomechanical loads was deduced. The change rules of thermomechanical buckling load and frequency were obtained.

Revitalising traditional Indian games: inclusive game adaptations for children with cerebral palsy

Background Children with cerebral palsy (CP) present unique challenges to physical activity due to various factors. Despite the benefits of inclusive approaches and adapted physical education, low- and middle-income countries face specific barriers including environmental, equipment, personal, policy, social and professional barriers. Traditional Indian games, with their cultural significance and potential therapeutic benefits, offer a promising avenue for inclusive adaptations. At present we couldn’t find any studies that explore’s the method of adaptation of traditional Indian games for children with cerebral palsy of varying functional levels. Purpose The aim of the study was to explore the adaptation of traditional Indian games for children with CP of varying functional levels. Methods Traditional Indian games were identified through ethnographic qualitative research, and adapted using the Delphi process involving experts from various fields. A total of 10 traditional games were selected based on their health benefits using an operationalised conceptual model. The CHANGE IT model of adapted physical activity was used to systematically adapt each game. Validation of the model was then performed on children with CP [a smaller sample size, n = 10] with different levels of functioning. Results The games varied in playing positions, surfaces and phases. Modifications included changes in game rules, play environment, equipment and time duration. The study validation through informal interview among the parents of CP children revealed that adapted traditional game protocol shown improvements in their children’s activity levels and participation. Conclusions While this is a preliminary exploration, no firm conclusion can be drawn. The model presented in this study lays the foundation for future randomised controlled trials to validate the effects of adapted traditional Indian games on children with cerebral palsy of different functional levels.

Study on the changing law of three-dimensional electric field during the evolution of seepage field in earth and rock embankment dams

Seepage is a common disease of earth and rock embankment dams, but due to the complex geological conditions, its location and seepage diameter are more difficult to be accurately detected. In order to accurately determine the seepage damage state of earth and rock dam materials during the evolution of seepage field, and to clarify the change rule of three-dimensional electric field of earth and rock embankment dams during the evolution of seepage field, this paper establishes a correlation model between seepage field and electric field based on porosity. Based on the model, the relationship between resistivity and critical hydraulic ratio drop during the infiltration damage of soil and rock dam is determined, focusing on the study of the three-dimensional electric field in the infiltration process of soil and rock dam body with the seepage field change characteristics and change rules, and obtaining the electric field response characteristics of the seepage field of the different hidden bodies, which provides a diagnostic basis for the realization of the subsequent leakage diagnostic technology of soil and rock dams.

Study on the synthesis mechanism of new α-FeOOH@3DGF material and its lithium storage performance

A new self-supporting material contained nanorods α-FeOOH and three-dimensional skeleton graphene foam (3D Graphene Foam, 3DGF) was prepared by hydrothermal method. The growth mechanism and phase change rules of nanorods α-FeOOH@3DGF were studied to obtain the electrochemical lithium storage performance. The results showed that growth mechanism of nanorods α-FeOOH was accompanied by the consumption of nanoparticles β-FeOOH. If the hydrothermal time reached to 12 h, the nanoparticle β-FeOOH phase completely disappeared with only rod-shaped α-FeOOH@3DGF single phase obtained. Rod-shaped α-FeOOH@3DGF was used as anode material of lithium-ion batteries and the reversible specific capacity remained at about 305 mAh·g−1 after charging and discharging 250 times at 500 mA·g−1, with significantly cycling stability compared with that of the monomaterial α-FeOOH.

Load prediction and energy efficiency improvement of steelmaking waste heat centralized heating systems under mild climate in China

HVAC energy consumption accounts for more than 50 % of the total building energy consumption globally and using industrial waste heat has huge potential for energy savings in central heating systems. Under the background of the use of renewable energy and the gradual rise of central heating in mild climate areas in China, it is worth paying attention to the problem of excessive energy consumption caused by the inaccurate load prediction of central heating systems when the ambient temperature changes. L City, Guizhou Province, is the first city with central heating in southern China. The temperature variation during winter in L City can manifest the climatic characteristics of a mild region. Therefore, based on the operational data of the steel waste heat central heating system in L City, Guizhou Province, China, during the heating season of 2022–2023, this study discusses the load prediction and energy-saving optimization strategy of the central heating system in a mild climate. SketchUp was used to conduct 3D modeling of the actual buildings in the heating area and TRNSYS was imported to simulate the system load. The difference between the heating load forecast and the actual operating data was analyzed in detail by using the calculation results. Based on the simulation results, the waste heat utilization strategy was adjusted and the influence of different heating schemes on the pump energy consumption under different load demands was discussed. The results reveal that based on the temperature change rule, the accurate load prediction can lead to a 28.64 % saving of the system energy. Concerning system energy consumption, by adjusting the water flow and choosing the large and small pump system, the energy saving amounts to 39.48 % compared with the traditional single-pump system. Meanwhile, in the transition season when the heating demand is less than 20 MW, the adjusted heating scheme can achieve a 38.5 % saving based on the constant flow scheme and a 5.4 % saving based on the constant temperature difference scheme. This article provides a scientific energy-saving solution for heating in mild climates using industrial waste heat, not only reducing energy consumption but also providing an important reference for the energy-saving renovation of heating systems in similar areas.

More substitutions changed team substitution strategy? An analysis of the FIFA World Cup 2002–2022

BackgroundThe increase in the number of substitutions allowed in football from three to five has profoundly influenced the game. The impact of the rule change on the FIFA World Cup needs further verification.MethodsA total of 2,151 team substitution opportunities and 2,410 substitutions in 384 matches from six FIFA World Cups (2002–2022) were analyzed to assess its impact. One-way ANOVA was used to assess differences in average substitution times among the six FIFA World Cups. Factors affecting the time of substitutions were explored using Generalized Linear Mixed Models.ResultsIn each FIFA World Cup, over 92% of substitutions occurred during half-time and the second half, with a higher proportion in knockout stage matches than group stage matches. Group stage substitutions tended to happen earlier, particularly when teams were losing. As allowed substitutions increased, multiple substitutions in one opportunity rose from 4% to 38%. Of the 2,410 substitutions in the six FIFA World Cups, 21.45% were offensive, 63.65% were neutral and 14.90% were defensive. Winning teams made the highest percentage of defensive substitutions, while drawing or losing teams made the highest percentage of offensive substitutions. Match status significantly affected the time of the first three substitutions, and the presence of extra time significantly affected the time of the fourth substitution.ConclusionAnalysis of substitutions in FIFA World Cups (2002–2022) reveals: Most substitutions occur during halftime and the second half; Substitutions are earlier in group stages, especially for losing teams; Increased allowed substitutions lead to more multiple-player substitutions; Defensive substitutions are more common when winning, while offensive ones are frequent when drawing or losing; Match status, ranking gap, extra time, game round, and substitution rules significantly influence the time of team substitutions.

Study on the Fire Characteristics of Dual Fire Sources and the Difference in Power Temperature of Different Fire Sources in Tunnel

To investigate the combustion characteristics of multiple fire sources in the tunnel caused by ‘jumping’ discontinuous fire spread, we utilized scaled model experiments, numerical simulation software, and theoretical research. Our study focused on analyzing the influence of different fire source powers on the temperature characteristics of double fire sources in the tunnel. We examined the temperature characteristics, critical wind speed, and change rule under various wind speeds, fire source spacing, and fire source powers. Additionally, we explored the temperature characteristics, critical wind speed, and change rule of different fire source powers under varying wind speed conditions. The mathematical model for roof temperature decay and the temperature decay coefficients of dual source fires were established through the analysis of scale-down model experiments and numerical simulations. In comparison to single-source fires, the temperature variations in the tunnel of dual source fires exhibit a more intricate pattern, with higher average temperature and temperature peak values. These values are influenced by factors such as fire source spacing and power. Numerical simulation software was utilized to investigate the impact of fire source spacing at 10 m, 15 m, and 20 m, as well as the effect of varying fire source power on the temperature distribution within a tunnel under consistent fire source position and growth coefficient. The study revealed that, with consistent double fire source position and ventilation conditions in the tunnel, the upstream fire source exhibited greater power than the downstream fire source, resulting in the lowest average and peak temperatures in the tunnel. This observation could potentially enhance escape and rescue operations within the tunnel. Similarly, the lowest average and peak temperatures in the tunnel were also identified, offering potential benefits for optimizing escape and rescue strategies in tunnel scenarios.

An Experimental Study on the Performance of Materials for Repairing Cracks in Tunnel Linings under Erosive Environments

Addressing the current lining cracking problem in coastal tunnels, this paper independently introduces a novel type of repair material for tunnel lining cracks—the composite repair material consisting of waterborne epoxy resin and ultrafine cement (referred to as EC composite repair material). Through indoor testing, we have analyzed the change rule of the mass change rate, compressive strength, flexural strength, and chloride ion concentration of the repair material samples in erosive environments, with the dosage of each component in the EC composite repair material being varied. We have also investigated the working performance, mechanical properties, and microstructure of the repair material. The results of this study show that when the proportion of each component of ultrafine cement, waterborne epoxy resin, waterborne epoxy curing agent, waterborne polyurethane, defoamer, and water is 100:50:50:2.5:0.5:30, the performance of the EC composite repair material in a chloride ion-rich environment is optimal in all aspects. When the mixing ratio of each component of the EC composite repair material is as stated above, the repair material exhibits the best performance in a chloride ion erosion environment. With this ratio of components in the EC composite repair material, the fluidity, setting time, compressive strength, flexural strength, and bond strength of the repair material in a chloride ion erosion environment can meet the requirements of relevant specifications, and it is highly effective in repairing tunnel lining cracks. The polymeric film formed by the reaction between the waterborne epoxy resin emulsion and the curing agent fills the pores between the hydration products, resulting in a densely packed internal structure of EC composite repair material with enhanced erosion resistance, making it very suitable for repairing cracks in tunnel linings in erosive environments.

Effects of Heat Treatment on the Chemical Composition and Microstructure of Cupressus funebris Endl. Wood

The effects of heat treatment on Cupressus funebris Endl. wood were examined under different combinations of temperature, time, and pressure. The chemical composition, crystallinity, and microstructure of heat-treated wood flour and specimens were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). Vacuum heat treatment led to changes in the functional groups and microstructure of C. funebris wood, and the relative lignin content decreased with increasing treatment temperature, which was significant at lower negative pressures. Cellulose crystallinity showed a change rule of first increasing and then decreasing throughout the heat treatment range, and the relative crystallinity ranged from 102.46% to 116.39%. The cellulose treated at 120 °C for 5 h at 0.02 MPa had the highest crystallinity of 44.65%. These results indicate that although heat treatment can improve cellulose crystallinity, very high temperatures can lead to decreased crystallinity. The morphology and structure of the cell wall remained stable throughout the heat treatment range; however, at elevated temperatures, slight deformation occurred, along with rupture of the intercellular layer.

Numerical Simulation Study of Wall Thickness Change Rule of Single Point Progressive Molding of Al5083

With the development and progress of science and technology, the application of single-point progressive molding is more and more extensive, but single-point progressive molding still exists the problem of excessive thinning of wall thickness of molded parts, which seriously affects the quality of molded parts. The article takes Al5083 plate forming cone as the research object, uses Abaqus finite element simulation software, according to the principle of single variable, respectively explores the influence of process parameters such as tool head diameter, layer spacing, feed rate and residual height on the average wall thickness reduction rate and the maximum wall thickness reduction rate of the molded parts. The results show that: increasing the tool head diameter, the average wall thickness reduction rate increases and the maximum wall thickness reduction rate decreases; the average wall thickness reduction rate and the maximum wall thickness reduction rate increase with the increase of ply spacing; the average wall thickness reduction rate and the maximum wall thickness reduction rate increase with the increase of the tool feed rate; the average wall thickness reduction rate decreases and the maximum wall thickness reduction rate increases with the increase of the residual height.

Laser-Tracing Multi-Station Measurements in a Non-Uniform-Temperature Field

Due to the increasing requirements for the improvement of the accuracy of large coordinate-measuring machines (CMMs), the laser-tracing multi-station measurement technology, as one of the advanced precision measurement technologies, is worth studying in depth in terms of its practical application for the compensation of errors in large CMMs. Since it is difficult to maintain a constant temperature of about 20 °C in the actual workshop under the influence of solar radiation and convective heat transfer, there is a gradient in the spatial temperature distribution, and the overall temperature changes with the influence of external factors with synchronous hysteresis, it is difficult for the actual calibration environment to meet the standard environmental requirements. Therefore, the influence of temperature and other environmental factors on the accuracy of laser ranging and large-scale CMM calibration should not be ignored. In this paper, on the basis of analyzing the temperature distribution and change rule of large CMM measurement space under different working conditions, the radial basis function (RBF) neural network algorithm was used to build a non-uniform-temperature field model, and based on this model and the measurement principle of the laser-tracking instrument, the method of laser tracking and interferometric ranging accuracy enhancement was put forward under a non-uniform-temperature field. Finally, based on the multi-station technique of laser tracing, an accurate solution for the volumetric error of large CMMs under the condition of non −20 °C ambient temperature was realized. Simulation results proved that compared with the traditional temperature-compensation method, the proposed method improved the measurement accuracy of the volumetric error of a large-scale CMM using laser-tracing multi-station technology in a non-uniform-temperature field by 33.5%. This study provides a new approach for improving the accuracy of laser-tracer multi-station measurement systems.

Instrumented mouthguards in elite-level men’s and women’s rugby union: characterising tackle-based head acceleration events

ObjectivesTo examine the propensity of tackle height and the number of tacklers that result in head acceleration events (HAEs) in elite-level male and female rugby tackles.MethodsInstrumented mouthguard data were collected...

Strength characteristics of different stress spaces of red sandstone under loading and unloading tests

Red sandstone tests were conducted on the rock mechanics test system to clarify the strength and failure characteristics of red sandstone under triaxial loading and different unloading confining pressure rates. Strength change rules of the red sandstone in various stress spaces were analyzed. Results show that a large initial confining pressure indicates a long yield section and large axial strain. A small unloading confining pressure rate indicates a long yield section and large axial strain at failure under the identical initial confining pressure. The confining pressure reduction increases with the unloading confining pressure rate increasing when the red sandstone fails. The stress path of unloading confining pressure weakens the red sandstone cohesion and strengthens its internal friction angle. The general octahedral shear stress formula for judging whether the red sandstone fails under loading and different unloading rates was acquired on the basis of the octahedral shear stress characteristics of the red sandstone. In addition, a 3D empirical criterion for evaluating the red sandstone strength was constructed through the deviator plane function of Eekelen and the strength envelope curve on the meridian plane. A great initial confining pressure indicates serious internal damage of the red sandstone at failure under the identical unloading rate of confining pressure. A low unloading rate of confining pressure indicates internal serious damage of the red sandstone at failure when the initial confining pressure is the same. The analysis of macroscopic failure characteristics revealed that the stress path significantly influences the failure mechanism of the red sandstone. The results are instructive for determining the stability of underground engineering of the red sandstone.

Extracellular vesicle-derived miR-146a as a novel crosstalk mechanism for high-fat induced atherosclerosis by targeting SMAD4

IntroductionExosome-miR-146a is significantly increased in patients with Atherosclerosis (AS), but its mechanism and effect on AS have not been fully elucidated. ObjectivesTo explore the change rule and mechanism of exosomes release, and the role and molecular mechanism of exosome-miR-146a in AS. MethodsWe isolated and identified exosomes from THP-1 macrophages after treating them with ox-LDL. Then used co-immunoprecipitation and silver staining to identify the proteins involved in regulating exosome release. PKH67 was used to label exosomes to confirm that cells can absorb them, and then co-culture with HVSMCs for cell proliferation and migration detection. The target genes of miR-146a were screened and identified through bioinformatics and luciferase activity assay, and the expression of miR-146a and related proteins was detected through qRT-PCR and Western blot in HUVECs. An AS model in LDLR-/- mice induced by a high-fat diet was developed to investigate the impact of exosome-miR-146a on AS. ResultsThe results showed that experimental foam cells from AS showed higher expression of miR-146a. It was observed that NMMHC IIA and HSP70 interacted to regulate the release of exosomes. And HUVECs can absorb exosomes derived from macrophages. In addition, we also found that miR-146a directly targeted the SMAD4 gene to modulate the p38 MAPK signaling pathway, thereby mediating HUVECs damage. Furthermore, exosome-miR-146a induced abnormal proliferation and migration of HVSMCs. The expression of miR-146a was significantly reduced in miR-146a-mimics mice and increased in miR-146a inhibitor mice whereas the inhibition of miR-146a effectively reduced while increasing miR-146a worsened AS in mice. ConclusionOur findings expressed the potential of miR-146a as a favorable therapeutic target for AS, however, further exploration is suggestive for deep understanding of the mechanisms regulating exosome-miR-146a release in vivo and to develop effective therapeutic strategies involving miR-146a.

GNSS location error reduction method for microtremor survey system based on EMD-CNN-LSTM

Abstract Large errors exist when the microtremor survey system uses the global navigation satellite system (GNSS) for static localization. Aiming at the problem that the existing methods cannot effectively weaken the random error and multipath error, an error weakening method based on Empirical Mode Decomposition (EMD), Convolutional Neural Networks (CNN), and Long Short-term Memory Networks (LSTM) is proposed. The model first uses EMD to decompose the high-frequency random error, then reconstructs the low-frequency component and extracts the local features using CNN, and finally learns the change rule of multipath error using LSTM and weakens it. The model can remove random errors in the early stage while reducing the interference of noise on the neural network in the later stage and then improve the accuracy of localization. The experimental results show that the model can effectively improve the localization accuracy in the case of short-time measurements so that the localization accuracy in the E, N, and U directions can be improved by 74.57%, 74.76%, and 71.86%, respectively, which is more than 10% higher than the localization accuracy improvement rate of the existing CNN-LSTM model.