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The profile rings with outer groove are widely used in advanced technological fields. To improve the filling accuracy of the cross-section profile of profile ring with outer groove, the deformation behaviors and filling features of the ring are explored. The deformation coefficient of the cross-section profile per revolution for profile ring with outer groove rolling process is introduced, and the change law of the deformation coefficient of the cross-section profile per revolution for profile ring with outer groove under different influencing factors is revealed. And then, the mathematical model of the deformation coefficient of the cross-section profile per revolution for profile ring with outer groove is established. Then, a prediction model of the ultimate forming dimension for profile ring with outer groove rolling process is proposed, and the specific application of the ultimate forming dimension model is clarified. Finally, the target forged ring of the profile ring with outer groove is designed to verify the ultimate forming dimension model by simulation and experiment. The results show that the prediction model can predict the rolling size of the profile ring with outer groove well. This study can provide a guide for the design and optimization of ring forgings with outer grooves in industrial production.

Magnetic skyrmion-based spin transfer nano-oscillators (STNOs) have been proposed as microwave signal generators and attracted enormous interest recently. However, the oscillation frequency of skyrmion-based STNOs is about 2 GHz, which is not so high for practical applications. In this paper, we create an annular groove in the surface of the free layer and put skyrmions in the annular groove. Due to the potential of the groove, skyrmions are confined to moving in the groove when driven by the spin-polarized currents. Through micromagnetic simulations, it is found that the frequency tunability of the STNO with the presence of the annular groove reaches to 15.63 GHz, which is more than 6 times higher than the case without the presence of the annular groove because of three reasons: the oscillation radius of skyrmions can be adjusted by the groove, the potential of the groove is larger than that of the edge and the groove can limit the diameter of skyrmions so that a larger number of skyrmions can be placed in the groove. Our results present the understanding of dynamic of skyrmions in an annular groove, which provides alternative possibilities for the design of skyrmion-based STNOs.

Bearings are an important part of the aviation equipment. The working accuracy, performance, service life, and reliability of bearings directly determine the performance of the aviation equipment. The manufacturing accuracy has been gradually improved with the ELID (electrolytic in-process dressing) grinding technology. The grinding-wheel wear has been an unavoidable problem in the ELID grinding of ball-bearing raceways. The ELID grinding-wheel profile needs to be promptly reshaped as soon as its profile deviation is greater than the allowable range. So far, few literatures are concerned about the precision evolution of the grinding-wheel profile under ELID conditions. There are no ready-made standards or instructions for the nonstandard ultra-precision bearings. Even the quality consistency is hard to be achieved. In this research, it aims to balance the service life of the grinding wheel and grinding accuracy. A comprehensively evaluating model is established, which includes two submodels. One is the contour-error submodel for assessing the groove raceway of bearings, in which the precision evolution principles are developed to work as the basis for this submodel. The other is the radial-wear rate submodel for evaluating the precision evolution of the ELID grinding wheel. In submodel 2, a special device is designed and established for the in situ monitoring of the radial-wear rate of the ELID grinding wheel under ELID conditions. It expands the application field of the precision-evolution principle for manufacturing the nonstandard bearings with ultrahigh precision. The rationality of the comprehensively evaluating model is verified by a group of optimal parameters derived from the five-factor-four-level orthogonal experiments. The conclusions can provide an important reference for balancing the wear of the grinding wheel and the grinding accuracy.

Sundaland's construction history has implications for the diversification and distribution of the genus Cyrtodactylus. One of the Cyrtodactylus known is C. marmoratus which taxonomically uncleared species. The aim of this study was to explain the taxon position of C. marmoratus from Java using the ND4 gene marker. Total of 10 Cyrtodactylus were analyzed based on the molecular analysis. Afterwards, it was used to construct the phylogenetic trees based on the maximum likelihood, maximum parsimony and Bayesian Interference. The p-distance analysis was tested to determine the differences between species. Interestingly, the phylogenetic trees indicated that the C. marmoratus from West Java was separated from C. marmoratus from Central Java. Some C. marmoratus from central Java were grouped with C. semiadii. It was also supported by the morphological characters of C. marmoratus from West Java which has distinguishing features i.e no pore on precloacal scales, no continuous pore on precloacal femoral scale, no deep precloacal groove, have 37 ventral scales and 20 lamellae sub digital on the fourth toe. Thus, it can be confirmed that C. marmoratus was a species complex with unclear distribution limits.

In order to study the milling machinability of Zr-based bulk metallic glass, a comparative experimental study on the surface roughness of the milling groove bottom surface for Zr-based bulk metallic glass was carried out in this paper. Through different processing materials, milling tools with different coatings, milling tools with different geometric parameters, and different processing conditions, a large number of comparative tests were carried out on the surface roughness of the milling groove bottom surface for Zr-based bulk metallic glass. The surface roughness values of the milling groove bottom surface are compared, studied, and analyzed from many angles (surface roughness Sa, Sq, Sz, Ssk, and Sku). The test results show that Zr-based bulk metallic glass has good milling machinability. It can obtain a low surface roughness value through the processing conditions and methods used in the test. The research content of this paper provides experimental basis for groove milling of Zr-based bulk metallic glass. At the same time, it also provides a strong test basis for the manufacture of Zr-based bulk metallic glass parts.

As the bearing rotation speed increases, the efficiency of the jet lubrication is drastically reduced due to the air curtain effect inside bearing cavity. Regarding this, by adding groove structures to the non-contact area of bearing inner ring surface, a novel method which can guide more oil flowing into the bearing raceway was proposed. By numerical simulation, the flow behavior of oil on the bearing inner ring surface was investigated. The results indicate that, compared with the traditional structure, the axial oil flow on grooved inner ring surface was enhanced, and more oil accumulated in the key lubrication area inside bearing cavity. Finally, by lubrication performance experiments, it was proved that the bearing lubrication performance had been improved by adding groove structures on its inner ring surface.

The technologies of low-rise housing construction with the use of small blocks of a special type, which make it possible to build the above-ground part of a building without using \"wet\" processes are described. It is shown that the presence of labyrinth grooves in the walls provides protection against blowing and makes it possible to ventilate the internal cavities.

We have developed a new process for the production of ultra‐precise variable line spacing (VLS) lamellar diffraction gratings through nanofabrication. The process enables the fabrication of full‐size X‐ray gratings with sub‐nanometre accuracy in groove depth, an optimal land‐to‐groove ratio, and uniform groove depth across the entire grating area. We also established a method for evaluating VLS groove density variation using stitched Fizeau interferometry. The measurements confirmed the exceptionally high accuracy of the VLS groove density in the fabricated gratings, which is well within the specification tolerances while the residual groove density errors are vanishingly small. The gold‐coated grating demonstrated near‐theoretical diffraction efficiency across the energy range of 100–1200 eV. Nanofabrication enables extremely precise and highly efficient variable line spacing diffraction gratings for X‐rays.

Purpose The purpose of this study is to investigate the sealing performance of different deep groove mechanical seals by considering the changing law of dynamic pressure effect and temperature gradient caused by high speed and high pressure. Design/methodology/approach A thermohydrodynamic lubrication model (THD) of the mechanical seal was constructed and solved using the commercial software FLUENT. The pressure and temperature distributions of the fluid under different groove types, as well as the sealing performance under different pressures, rotational speeds and sealing gaps, are obtained. Findings The annular groove (AG) can effectively reduce the temperature, and the T-type spiral groove (STG) can effectively inhibit the leakage. The increase of pressure and rotational speed leads to the enhancement of dynamic pressure effect and the increase of leakage, while the sealing gap increases and the leakage increases while taking away more heat. The choice of groove type is very important to the impact of sealing performance. Originality/value In consideration of the beneficial effect of deep grooves on cooling performance, the viscous temperature equation and the impact of the thermodynamic lubrication model are evaluated in conjunction with the sealing performance of four distinct groove types. This approach provides a theoretical basis for the optimal design of mechanical seals. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2024-0184/

We introduce a tabletop high harmonic generation (HHG) scatterometry technique to extract structural and material characteristics of periodic nanostructures. Grazing incidence reflection scatterometry enables fast and robust measurements of linewidth and groove height with 20 nm and 2 nm precision respectively, paving the way for ultrafast spectroscopy on layered heterostructures.