Search

Spiral bevel gears are extensively employed in mechanical transmissions; however, they are prone to adhesive wear when operating under high-speed and heavy-load conditions. Research indicates that the tooth surface roughness of gears significantly influences the friction and wear of the meshing gears. The present study delves into the origins of tooth surface roughness through the integration of the W-M function and fractal theory. Utilizing an involute helical gear with surface roughness for tooth cutting, a three-dimensional model is established with roughened tooth surfaces. This paper introduces an approach to developing three-dimensional gear models with roughness and applies the finite element method to perform thermodynamic analysis on gears exhibiting diverse levels of surface roughness. The thermal analysis of gears with varying degrees of roughness was conducted using the finite element method. Comparative analysis of the results under specific operating conditions elucidated the impact of roughness on tooth surface temperature rise. In order to validate the simulation model, an experimental test platform for spiral bevel gears of identical size was established. This model integrates tooth surface roughness with thermodynamic analysis, allowing for the rapid assessment of tooth surface temperature rise under different machining conditions, and reducing the cost of validating predicted tooth surface load-carrying capacity.

Shoot architecture in maize is critical since it determines resource use, impacts wind and rain damage tolerance, and affects yield stability. Quantifying the diversity among inbred lines in heterosis breeding is essential, especially when describing germplasm resources. However, traditional geometric description methods oversimplify shoot architecture and ignore the plant’s overall architecture, making it difficult to reflect and illustrate diversity. This study presents a new method to describe maize shoot architecture and quantifies its diversity by combining computer vision algorithms and persistent homology. Our results reveal that persistent homology can capture key characteristics of shoot architecture in maize and other details often overlooked by traditional geometric analysis. Based on this method, the morphological diversity of shoot architecture can be mined (quantified), and the main shoot architecture types can be obtained. Consequently, this method can easily describe the diversity of shoot architecture in many maize materials.

Abstract Background Phenotypic plasticity is defined as the phenotypic variation of a trait when an organism is exposed to different environments, and it is closely related to genotype. Exploring the genetic basis behind the phenotypic plasticity of ear traits in maize is critical to achieve climate-stable yields, particularly given the unpredictable effects of climate change. Performing genetic field studies in maize requires development of a fast, reliable, and automated system for phenotyping large numbers of samples. Results Here, we develop MAIZTRO as an automated maize ear phenotyping platform for high-throughput measurements in the field. Using this platform, we analyze 15 common ear phenotypes and their phenotypic plasticity variation in 3819 transgenic maize inbred lines targeting 717 genes, along with the wild type lines of the same genetic background, in multiple field environments in two consecutive years. Kernel number is chosen as the primary target phenotype because it is a key trait for improving the grain yield and ensuring yield stability. We analyze the phenotypic plasticity of the transgenic lines in different environments and identify 34 candidate genes that may regulate the phenotypic plasticity of kernel number. Conclusions Our results suggest that as an integrated and efficient phenotyping platform for measuring maize ear traits, MAIZTRO can help to explore new traits that are important for improving and stabilizing the yield. This study indicates that genes and alleles related with ear trait plasticity can be identified using transgenic maize inbred populations.

High-fill culverts placed in valley topography have a complex earth pressure distribution law due to their locations around culverts in various valley topography conditions. In order to investigate the influence of valley topography on the earth pressure around the culvert of high-fill arch culverts, an interaction model of "topography-culvert-fill" was established by using centrifugal model test and numerical simulation method. Additionally, the distribution laws of earth pressure around the arch culverts and earth pressure concentration coefficient Ks at the top of the culvert under different valley widths B and valley slopes α were analyzed and were compared with the latest Chinese culvert design code. Furthermore, the mechanism of earth pressure formation of high-fill arch culverts under valley topography was presented. The research findings are as follows: (1) The influence of the valley width B on the earth pressure concentration coefficient Ks at the top of the culvert is significant, and the increment of the earth pressure concentration coefficient Ks at the top of the culvert is larger when B is 4D−6D（D is the clear span of arch culvert）. (2) When B is less than 4D, the topography would play the role of load reduction to the culvert. (3) With valley slopes ranging from 45° to 60°, the earth pressure at the tops and Ks would be affected dramatically. (4) When fill height is 20 m with α >70°, Ks≤1; and when 40 m fill height with α >50°, Ks≤1. (5) The Ks recommended by the latest Chinese culvert design code differs to some extent from those by centrifugal model test and numerical simulation. In the case of α =45° with a small B value, the earth pressure concentration coefficient Ks at the top of a culvert of the code is more conservative. (6) Ks of high-fill arch culvert in valley is related to the formation of arch top compaction area and isobaric surface. The arch top compaction area can cause the earth pressure concentration on the top of the arch culvert, and cause the vertical earth pressure of the soil around the compaction area to be arched. At a certain depth approaching the surface of the fill, the arch distribution gradually transits to the horizontal distribution, thus forming an isobaric surface. The upper load of the isobaric surface will be dispersed on the valley slope, so the unloading effect of the valley topography can be exerted.

In order to explore the time-varying mesh stiffness and dynamic parameters of bevel gears with different surface roughness, the fractal dimension and characteristic scale coefficient are calculated to determine the fractal dimension of tooth surfaces of spiral bevel gears with rough features. Spiral bevel gears with distinct surface roughness are obtained by simulating the gear-cutting process, and after analysis, a dynamic differential equation for spiral bevel gears considering the surface roughness is proposed. By combining the differential equation with finite element analysis (FEA), the time-varying mesh stiffness of spiral bevel gears with various surface roughness is determined. FEA analysis yields the time-varying mesh stiffness under different surface roughness. The vibration velocity and acceleration of spiral bevel gears with different surface roughness are revealed by combining the time-varying mesh stiffness with the dynamic equation. The intricate relationship between gear surface microstructure and its mechanical behavior during engagement is thoroughly analyzed. A comprehensive dynamic parameter model is proposed to capture the influence of microtopological changes on gear dynamics. The results can offer valuable insights for the design and optimization of bevel gears, aiming to enhance their performance and durability.

Aims: The outcomes of total knee arthroplasty (TKA) are affected by many factors. This study aims to evaluate whether changes in the posterior tibial slope (PTS) affect patients’ outcomes after cruciate-retaining TKA by affecting tibiofemoral articular contact kinematics. It was hypothesized that changes in PTS affect the outcomes of PCR TKA by affecting tibiofemoral articular contact kinematics. Methods: A total of 60 knees (30 patients) that underwent posterior cruciate-retaining TKA (with the same size prosthesis) for medial osteoarthritis were assessed preoperatively and one year postoperatively. Before and after TKA, changes in the PTS, as seen on lateral radiographs, were noted. The knees were placed in groups according to these PTS changes (preoperative value − postoperative value): group 1 >3° change and group 2 ≤3° change. Knee kinematics were observed under mid-flexion weight-bearing conditions and were compared between the two groups using the two-dimensional/three-dimensional registration technique. Pain was measured using the visual analog scale, and knee function was assessed using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the Knee Society Score (KSS). Results: Group 2 experienced paradoxical anterior motion of the medial femoral condyle postoperatively, but group 1 did not. A comparison of the results of the TKA between the two groups showed a significant difference in pain using the visual analog scale, and knee function of the KSS and the WOMAC (P

In order to improve the dispersibility of graphene in engine oil, the in - situ reduction method was adopted, so the complicated processes such as reduction of graphene oxide, freeze - drying and grinding operation to obtain powder were omitted, and the production cost was cut. The graphite oxide was reduced with the help of the reducibility of the base oil to produce a fine - sized, uniformly dispersed graphene engine oil improver. Furthermore, in the preparation process of the graphene oxide engine oil improver, anhydrous ethanol was used to wash the graphene oxide in the second half of the centrifugal washing process of graphene oxide, which greatly improved the dispersion of the graphene in the base oil. In the reduction process of graphene oxide, vitamin C was used as the reduction initiator, making the process environmentally friendly. Results obtained from the friction and wear test carried out on the MS - T3000 friction and wear instrument showed that when the graphene nanoparticle used as lubricant additive, the typical sheet structure and curl morphology of graphene could be observed on the surface of the attached object, indicating that "miniature ball bearing effect" was realized due to the addition of graphene, and thus a good solid lubrication effect was obtained. A large amount of graphene attaching to the metal surface reduced the shedding of the hard phases of the metal surface, protected the metal surface together with the engine oil and significantly improved the friction and wear properties of engine oil, therefore, showed significant effect on reducing the wear on automobile engines.