Gap Radius Research Articles

Investigation of a New Vibration-Absorbing Roller Cage Shoe with a Magnetorheological Damper in Mine Hoisting Systems

In the mine hoisting system, rigid guide failures and the influence of internal and external airflow intensify vessel transverse vibration, heightening demands on operational safety and equipment reliability. This paper focuses on integrating magnetorheological dampers and disc springs as the roller cage shoe buffer for vibration control, resulting in an innovative buffer device. The structure and magnetic circuit were meticulously designed. Using Maxwell simulation, we analyzed the impact of magnetic circuit parameters—specifically the damping gap and core radius—on the magnetorheological damper. We optimized these parameters through orthogonal testing to enhance damping and vibration reduction. This led to a notable 58% increase in the damper output force. A virtual prototype of the lifting system under actual working conditions was established. A simulation analysis verified the vibration-damping performance of the optimized roller cage shoe. The results indicate that the new roller cage shoes effectively inhibit transverse vibration, surpassing traditional roller cage shoe performance. This is scientifically and practically significant for ensuring safe cage shoe lifting system operation. This paper can provide a crucial theoretical basis for the design of roller cage shoes in ultra-deep mine lifting systems.

Predicting of Process Parameters for Theoretical Concentrated Stress of Fatigue Notch Coefficient of Auto Parts Using Virtual Recognizable Performance Evaluation Research.

This paper analyzes the structure of the key parts of the car belt guide, and the average stress of the vulnerable parts is simulated by analysis software. The theoretical stress of the section is calculated. The theoretical stress concentration factor () is given. The relation between the gap radius and the notch coefficient () was studied according to a previous calculation formula. The tensile tests of real products are used as reference data. The results showed that and are linear in most cases, but there are also cases of non-compliance. The relationship between the fatigue notch coefficient and the theoretical stress concentration coefficient was closely related to the service life and fatigue strength of the product. In addition, we found that the size and direction of warpage improved significantly with the increase of fillet size, which was not consistent with the effect of adding glass fiber material. The rounded corners of ordinary PP materials usually displayed forward warping, but the addition of glass fiber into PP materials made the degree of warping smaller, or even led to reverse warping. The size of rounded corners is an important optimization parameter. The relationship between and was studied from the perspectives of virtual measurement (VM) and recognizable performance evaluation (RPM). According to abnormal filling pressure, these relationships were compared with filling data to generate a fracture initiation control model. Based on a large amount of normal process data and quality inspection data, the historical data (causes) and quality inspection data (results) were combined.

Ground State Properties and Shape Transition of Even-Even 76Os, 78Pt, 80Hg and 82Pb Isotopes in the Framework of Skyrme Hartree-Fock-Bogoliubov Theory

The Hartree-Fock-Bogolyubov (HFB) theory is a good theoretical approximation for describing the nuclear structure of neutron-rich deformed nuclei, it is generalized the HF theory with BCS pairing theory. In this work, ground-state properties of even-even 76Os, 78Pt, 80Hg and 82Pb isotopes from proton drip-line to neutron drip-line have been studied in the framework of the axially deformed Hartree-Fock-Bogoliubov (HFB) method with two Skyrme nucleon-nucleon force HFB9 and UNE1. The numerically calculated results of binding energy, two neutron separation energy, two neutron shell gap, quadrupole deformation, neutron pairing gap and charge radius are discussed and compared with the available values of the experiment, Finite Range Droplet Model (FRDM), Relativistic Mean-Field (RMF) and Hartree-Fock-Bogoliubov based on D1S Gognay force. The energy surface curves are plotted for some isotones of the investigated nuclei, the transition in the shapes was clear with the change in the number of neutrinos. Our calculations show good agreements in comparison with other data and results.

Ultrasonic trapping and collection of airborne particulate matter enabled by multiple acoustic streaming vortices

The capability of trapping and collecting airborne particulate matter is of great applications in the fields of environmental engineering, healthcare systems, energy engineering, and so forth. In this work, we show a facile strategy of trapping and collecting airborne particulate matter by a simple and compact ultrasonic device system. In this device, a radiation plate is bonded with a Langevin transducer for generating circular standing flexural waves (CSFWs) in the plate. Under the excitation of the CSFWs in the radiation plate, an acoustic field and an acoustic streaming field can be induced in the air gap formed by the radiation plate and a sampling plate. Through numerical simulations, we find that the multiple acoustic streaming vortices symmetric about the central axis in the air gap are responsible for trapping and collecting airborne particulate matter onto the sampling plate, while acoustic radiation force contributes little. Also, it is numerically found and experimentally verified that the resonant acoustic field and the accompanying acoustic streaming field can be tuned by varying the thickness of air gap. Through experimentation, we investigate and clarify the dependency of collection performance on parameters such as the air gap thickness and radius, sonication time, driving voltage, and the angle between the radiation plate and the sampling plate. Due to its contactless and mild handling attributes, our ultrasonic airborne particulate matter sampler can circumvent the clogging and secondary pollution issues and ensure device reusability and little damage to samples compared with other airborne particulate matter processing methods.

Computational Study on the Interaction and Moving of ssDNA through Nanosheets

The adsorption characteristics and moving through nanopores of a single-stranded deoxyribonucleic acid (ssDNA) molecule on monolayers, such ashexagonal boron nitride and graphene nanosheets, were studied using the continuous approach with the 6–12 Lennard–Jones potential function. The ssDNA molecule is assumed to be at a distance l above the sheet, and the relation between the minimum energy location and the perpendicular distance of the ssDNA molecule from the nanosheet surface is found. In addition, by assuming that there is a hole in the surface of the nanosheet as a pore, the interaction energies for the ssDNA molecule moving through the pore in the surface of the nanosheet (used to calculate the radius p of the hole) are obtained, which provides the minimum energies. Furthermore, a comparative study with graphene was performed in order to compare with hexagonal boron nitride nanosheets. Our results indicate that the binding energies of the ssDNA onto graphene and hexagonal boron nitride nanosheets are approximately 15.488 and 17.582 (kcal/mol), corresponding to perpendicular distances of l=20.271 and l=20.231 Å, respectively. In addition, we observe that the ssDNA molecule passes through graphene and hexagonal boron nitride nanopores when the gap radius p>7.5 Å. Our results provide critical insights to understand and develop the interactions and translocation of DNA molecules with and through nanosheets.

Design of a Compact Embedded Hydraulic Power Unit for Bipedal Robots

This letter proposes a design method of a compact embedded hydraulic power unit (HPU) for a bipedal robot and a controller to regulate the supply pressure. The HPU consists of an integrated pump-motor unit. The unit is immersed in hydraulic oil for efficient space utilization and heat dissipation from the motor. This HPU design is analyzed to establish a relationship between the thermal variables and the motor design parameters such as gap radius and wire radius via its thermal and electrical modeling. Through this analysis, the design parameters of suitable pump-driving motor are chosen. This letter also proposes a control method for the HPU to regulate the supply pressure while minimizing the energy loss caused by the bypass through a pressure-regulating valve. The HPU is mounted on top of the bipedal robot platform, LIGHT, with twelve degrees of freedom actuated by the proposed HPU. Finally, the durability of the designed HPU is demonstrated through a long-term driving test at a high pressure. Furthermore, air-walking and squat motion experiments are conducted with the bipedal robot to demonstrate the capabilities of the HPU and its controller.

Analysis and experiment of deformation and draping characteristics in hemisphere preforming for plain woven fabrics

Currently, the analytical analysis cannot describe the deformation and draping behavior during hemisphere preforming using plain woven fabrics, especially considering the fabric deformation outside the hemisphere and the effect of processing parameters. Thus, an analytical analysis was established to characterize the sliding and shearing behavior for a typical hemisphere preforming for the plain woven fabric. The experiments were conducted, and the root mean square values for the sliding and shearing between the analytical and experimental results are small, demonstrating the effectiveness of the analytical analysis. With the reduction of the corner radius of the die and the gap between the punch and die, the sliding ratio is larger than 1.0, indicating an increase in yarn sliding . In addition, the shearing deformation in the quasi tensile region is still generated and reaches a maximum value of 4.5° both in analytical prediction and in experimental measurements. Moreover, the analytical analysis is capable of characterizing the draping degree, which is shown to increase non-linearly with increasing punch depth. The reduction of the gap and corner radius enlarges the draped region, improving the draping degree. This work demonstrates that an analytical analysis can be used to gain an insight into the deformation and draping mechanisms of plain woven fabrics.

On the Diversity of Asymmetries in Gapped Protoplanetary Disks

Abstract Protoplanetary disks with large inner dust cavities are thought to host massive planetary or substellar companions. These disks show asymmetries and rings in the millimeter continuum caused by dust trapping in pressure bumps and potentially vortices or horseshoes. The origin of the asymmetries and their diversity remains unclear. We present a comprehensive study of 16 disks for which the gas surface density profile has been constrained by CO isotopologue data. First, we compare the azimuthal extents of the dust continuum profiles with the local gas surface density in each disk and find that the asymmetries correspond to higher Stokes numbers or low gas surface density. We discuss which asymmetric structures can be explained by a horseshoe, a vortex, or spiral density waves. Second, we reassess the gas gap radii from the 13CO maps, which are about a factor of 2 smaller than the dust ring radii, suggesting that the companions in these disks are in the brown dwarf (∼15–50 M Jup) or super-Jovian (∼3–15 M Jup) mass regime on eccentric orbits. This is consistent with the estimates from contrast curves on companion mass limits. These curves rule out (sub)stellar companions (q > 0.05) for the majority of the sample at the gap location, but it remains possible at even smaller radii. Third, we find that spiral arms in scattered-light images are primarily detected around high-luminosity stars with disks with wide gaps, which can be understood by the dependence of the spiral arm pitch angle on disk temperature and companion mass.

Analytical and Experimental Investigation of the Solar Chimney System

In this, paper the authors propose a new simplified method of solving the problem of air flow through a solar chimney system using a classical system of equations for the principles of conservation (momentum, mass, and energy), as well as a general solution to research the problem using similarity theory. The method presented in this paper allows one to design a solar chimney. The theoretical analysis was compared with experimental studies on existing solar towers. The experimental and theoretical studies were satisfactorily consistent. For clarity, the phenomenon of heat flow in the solar chimney was described using dimensionless numbers, such as the Reynolds, Grashof, Galileo, Biot, and Prandtl numbers. In the equations for the dimensionless geometric parameters, the ratios of the collector radius to the thickness gap, height, and chimney radius were used. The method used to test the system of equations allows us to analyse various solar collectors easily. In the scientific literature, there is a lack of a simple calculation method to use in engineering practice, suitable for each type of solar chimney independent of dimensions and construction parameters.

Double diffusive mixed convection study in a vertical annulus at different aspect ratio and Richardson number

The present study has been considered in heat, mass transfer and the reversal flow occurrence inside the annulus of concentric vertical cylinders numerically. Both the thermal buoyancy and the buoyancy due to different concentrations are of equal magnitude and direction. The forced flow direction effect is investigated. The problem is considered a laminar flow and steady state. The influencing parameters are identified for the problem are Richardson number, Lewis number, and length to gap ratio and Radius ratio. The dimensionless gap is kept constant at unity. The Richardson number is varied from 0.1 to 10, dimensionless length from 5 to 25, the dimensionless radius ratio from 1.5 to 11 and the lewis number from 0.1 to 10. The dimensionless temperature and concentration distributions are illustrated at various range of parameters. In addition, the average values concerning Nusselt as well as Sherwood numbers are correlated. The reverse flow is examined at both aiding and opposing flows. The reverse flow existence is affected by the Richardson number and the length to gap ratio. The value concerning thermal Grashof number is stable at 104.

Design, modeling and experimental verification of circular Halbach electromagnetic energy harvesting from bearing motion

Recently, bearing health condition monitoring has attracted considerable attention due to its great significance to prolong the lifespan and improve the system reliability of key industrial equipments. For the purpose of improving the reliability and effectiveness of energy harvesting in the monitoring node of industrial equipments, this paper proposes circular Halbach electromagnetic energy harvesters for extracting the electrical energy from the rotational motion of bearings to supply the monitoring units. The magnetic distribution model of the circular Halbach array is derived to investigate the magnetic field enhancement using different arrangement modes and structural parameters. The effect of gap, magnetic shape and distribution radius on the magnetic field is numerically discussed to obtain the proper configuration of circular Halbach array for performance enhancement. The experimental results of the fabricated prototype demonstrate the effectiveness of the proposed model and optimization design for enhancing the energy harvesting performance. Moreover, voltage response and power output under different connection modes of multi-coil are experimentally discussed for increasing efficiency and reducing the cost and difficulty of interface circuits. Under the rotational speed from 600 rpm to 1000 rpm, the proposed harvester can generate the voltage of 2.79–4.59 V and the maximum average power of 50.8–131.1 mW.

Continuous Approximation for Interaction Energy Transfer of DNA through Lipid Bilayers

In this study the interaction energies for single-stranded DNA and double-stranded DNA molecules with a lipid bilayer are investigated. The 6-12 Lennard-Jones potential and continuous approximation are used to derive analytical expressions for these interaction energies. Assuming that there is a circular gap in the lipid bilayer, we determine the relationship of the molecular interaction energy, including the circular gap radius and the perpendicular distance of the single-stranded DNA and double-stranded DNA molecules from the gap. For both single-stranded and double-stranded DNA molecules, the relationship between the minimum energy location and the hole radius b is calculated; in the case of the double-stranded DNA molecule, we assume that the helical phase angle ϕ is equal to π. By minimizing the total interaction energies, the results demonstrate that the single-stranded DNA and double-stranded DNA molecules move through a lipid bilayer when the gap radius b> 10 Å and b> 13.8 Å, respectively. The results present in this project can be leveraged to understand the interactions between cell-penetrating peptides and biomembranes, which may improve gene and drug delivery.

Numerical Study on the Propagation of Premixed Flames in Confined Narrow Disc-Shape Chambers

ABSTRACTThe laminar flame propagation in narrow confined disc-shape chambers of millimeter scale is investigated, concerning the flame front displacement speed and the influences from the changes of the gap width and radius. An asymptotic analysis treating the flame front as a discontinuity successfully predicts the velocity profiles of the flame front and illustrates the importance of heat release parameter and laminar flame speed of the fuel. The unsteady flame propagation process is simulated by a full numerical computation which employs the n-butane/air mixture as the reactant. The numerical simulation emphasizes the sensitivity of spatial scale to the flame propagation in narrow spaces, indicating that the acceleration rate and the maximum speed of the flame have a non-monotonic relation with the gap width, of which the optimal value is about 0.8 mm. Faster flame propagation is favored for larger gap radius due to stronger flame straining, but it is restricted by the gap width.

Removal of CrN Contamination from EUV Mask Backside Using Dry Cleaning

For EUV lithography, a reflective mask is essential because of use of the strong energy, wavelength of 13.5 nm. The EUV mask consists of multi-layered, multi-material structure and is susceptible to various contaminants. Since EUV lithography process should be used in a high vacuum environment, an electrostatic chuck (ESC) is used to fix or hold the EUV mask using electrostatic force. In general, in order to use ESC chuck, it needs a thin conductive layer (CrN layer) on the backside. However, the contact points of the electrostatic pin chuck can make exfoliation of conductive CrN layer producing CrN particles. If these particles are present on the backside of the mask, CD or DOF may be affected during EUV exposure. The 1 μm particle can leads to a gap radius of 42mm [4]. Moreover, these backside particles may travel to the front side. Therefore, backside cleaning should be performed to remove particles from the mask backside surface.

Generalized optimization procedure for rotational magnetized direction permanent magnet thrust bearing configuration

Optimization of rotational magnetized direction permanent magnet thrust bearing configuration is carried out using generalized three-dimensional mathematical model. The bearing features namely axial force and stiffness are maximized using in-house developed mathematical expressions solved using MATLAB. The design variables selected for the optimization are axial offset, number of ring pairs, air gap and inner radius of inner and outer rings. The maximized axial force values of the optimized configuration are validated with the finite element analysis results. To overcome the high computational cost associated with three-dimensional equations, generalized method of optimization is sucessfully demonstrated using plots representing variation of optimal design variables as a function of air gap with respect to bearing’s outer diameter. Simple and useful method of using the generalized plots for the process of optimization is presented by dimension optimization of representative bearing configuration with a particular aspect ratio. The proposed optimization using mathematical model and generalized approach assists designer in selecting optimized geometrical parameters of rotational magnetized direction thrust bearing configurations easily for variety of high-speed applications.

林窗尺度对侧柏人工林土壤微生物量和功能多样性的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 林窗尺度对侧柏人工林土壤微生物量和功能多样性的影响 DOI: 10.5846/stxb201605261016 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家"973"重点基础研究发展计划项目（2012CB416904）；国家林业公益性行业科研专项（201104075）；江苏省高校优势学科建设工程项目资助（PAPD） Effects of forest gap size on the biomass and functional diversity of soil microbes in Platycladus orientalis plantations Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:微生物活性是影响土壤碳循环等地下生态系统过程的重要因素。以徐州市侧柏（Platycladus orientalis （L.） Franco）人工林为研究对象，以未受干扰的侧柏林为对照（CK），设置半径分别为4、8、12m的3种尺度近圆形林窗，从林窗边缘（D1）到距林缘4m （D2）及8m处林下（D3）水平梯度上分析土壤微生物量碳（MBC）、氮（MBN）和代谢功能多样性的变化。结果表明：1）与CK相比，林窗样地土壤MBC总体降低，MBN含量显著下降（P<0.05），MBC/MBN显著上升（P<0.05）。在3种尺度林窗中，MBC在大林窗偏小，MBN在小林窗偏小；MBC/MBN总体上随林窗尺度增大而减小。2）与CK相比，大中林窗降低了土壤微生物代谢活性（AWCD），小林窗变化不大。从D1到D3点，小林窗的AWCD先降后升，中林窗呈上升趋势，大林窗则相反。而且林窗降低了土壤微生物对各类碳源的利用，主要利用聚合物类和氨基酸类碳源，中林窗样点对碳水化合物和氨基酸类小分子碳源的利用最低。3）林窗总体提高了土壤微生物功能多样性，其中多样性（H'）、丰富度（S）和均匀度（E）3个指数在各点之间均无显著差异，小林窗和CK的优势度指数（Ds）显著大于（P<0.05）大林窗。侧柏林人工林窗对土壤微生物量和功能多样性的影响有着明显的尺度和位置梯度效应，林窗有望促进侧柏林土壤碳固持和大分子物质降解，提高其应对全球气候变化的能力，综合而言，中尺度林窗对侧柏林生态功能的发挥较为有利。 Abstract:The metabolic activity of microbes profoundly influences underground ecological processes, similar to the soil carbon cycle. However, even though forest gap research has addressed underground processes, studies of microbial functional diversity remain scarce. In the present study, we mainly investigated changes in the microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), and microbial functional diversity (AWCD) of the soil along a horizontal gradient of large, medium, and small forest gaps (radii of 4, 8, and 12m, respectively) in a plantation of Platycladus orientalis (L.) Franco in Xuzhou (China) during the summer. The corresponding gap sizes, which were calculated as the ratio of gap radius to the height of trees at the edge of the gap, were 1.5, 1, and 0.5, respectively. Three forest gap gradients, namely, forest gap edge (D1), 4m outside the gap (D2), and 8m outside the gap (D3), were chosen. After forest gap formation, soil MBC decreased on the whole and MBN decreased significantly (P<0.05), where as the MBC/MBN ratio increased significantly (P<0.05). Among the three gap types, the MBC and MBN were lowest in the large and small gaps, respectively, with minimum levels of 2069.42 and 126.21mg/kg. Meanwhile, the MBC/MBN ratio varied from 10.50 to 19.96 and generally decreased with increasing gap size. In addition, forest gaps reduced soil AWCD, and the effect size varied with gap size, with the smallest effects observed in the small gaps. From D1 to D3, the AWCD of the small gaps initially declined and then increased, whereas it continuously increased in the medium gaps and continuously decreased in the large gaps. Furthermore, forest gaps also reduced the carbon consumption of soil microbes, and the use of carbohydrates and amino acids was the lowest in the medium gaps, whereas that of polymers was the highest in the medium and small gaps. In D1, the soil microbes consumed less carbon in the medium gaps than in the small gaps. The present study also revealed that forest gaps improved microbial functional diversity. Although there were no significant differences between the diversity (H'), richness (S), and evenness (E) indices of the three gradients, the dominance index (Ds) values of D3 and D1 were significantly higher in the small gap and control plot and were significantly greater than those of D1 and D2 in the large gap (P<0.05). The effect of forest gap on the diversity indices varied with gap scale and location. The main carbon sources used by the soil microbes were polymers and amino acids. In short, the effect size of forest gap on soil MBC, MBN, and microbial functional diversity in P. orientalis plantations vary remarkably with scale. Therefore, forest gaps can promote soil carbon sequestration and macromolecular substances degradation and improve the ability of forest ecosystems to adapt to global climate change. Furthermore, medium gaps were the most efficient for improving the ecological function of forest plantations. 参考文献 相似文献 引证文献

An enhanced spring-mass model for stiffness prediction in single-lap composite joints with considering assembly gap and gap shimming

An enhanced spring-mass stiffness model was proposed, which was based on the supposition that the transverse shear stress under preload satisfies conical and spherical envelope, to predict the stiffness of the single-lap single-bolt composite joint with considering assembly gap and gap shimming. The validation experiments were conducted for different configurations. It shows that the analytical results were all in good agreement with the experimental results. Meanwhile, experimentally validated finite element model was used as an assistant validation in consideration of convenience and cost saving. The presented analytical model was then used for parameter studies, including gap size, gap radius and shim thickness. The major conclusions are: 1) as gap size increases 0.1 mm, the shear stiffness decreases about 1.1%; 2) the shear stiffness quickly becomes zero when the gap radius exceeds the boundary of the highly stressed portion; 3) shim thickness has much greater influence on the bolt stiffness than on the shear stiffness.

Tunable plasmon-induced transparency in plasmonic metamaterial composed of three identical rings

We numerically investigated the plasmon-induced transparency (PIT) effect in a three-dimensional plasmonic metamaterial composed of three identical rings. It is illustrated that the PIT effect appears as a result of the destructive interference between the electric dipole and the quadrupole resonance mode. By tuning gap distance, radius or rotation angle of the metamaterial, the required transmission spectra with a narrow sharp transparency peak can be realized. In particular, it is found that an on-to-off amplitude modulation of the PIT transparency window can be achieved by moving or rotating the horizontal ring. Two dips move to high frequency and low frequency regions, respectively, in the transmission spectra by moving the horizontal ring, namely, the width of transmission peak becomes larger. With the rotation of horizontal ring, both width and position of transmission peak are kept invariant. Our designed structure achieved a maximum group index of 352 in the visible frequency range, which has a significant slow light effect. Moreover, the PIT effect is explained based on the classical two-oscillator theory, which is in well agreement with the numerical results. It indicates our proposed structure and theoretical analysis may open up avenues for the tunable control of light in highly integrated optical circuits.

Optimization of Axially Magnetized Stack Structured Permanent Magnet Thrust Bearing Using Three-Dimensional Mathematical Model

This work deals with optimization of axially magnetized stack structured permanent magnet (PM) thrust bearing using generalized three-dimensional (3D) mathematical model having “n” number of ring pairs. The stack structured PM thrust bearing is optimized for the maximum axial force and stiffness in a given cylindrical volume. matlab codes are written to solve the developed equations for optimization of geometrical parameters (axial offset, number of ring pairs, air gap, and inner radius of inner and outer rings). Further, the results of proposed optimization method are validated using finite element analysis (FEA) and further, generalized by establishing the relationship between optimal design variables and air gap pertaining to cylindrical volume constraint of bearing's outer diameter. Effectiveness of the proposed method is demonstrated by optimizing PM thrust bearing in a given cylindrical volume. Mathematical model with optimized geometrical parameters dealt in the present work helps the designer in developing PM thrust bearings effectively and efficiently for variety of applications.

Observation of the Earth’s surface from the space through a gap in a cloud field

For purposes of atmospheric correction of satellite images, the problem of estimating the distance from the cloud gap center at which the effect from cloudiness on the satellite image can be neglected is posed. The Monte Carlo method with the backward simulation scheme is used. The value for the radius of the gap in continuous cloudiness at which the influence of clouds changes the received radiation intensity by 10% has been obtained. Dependences of the received intensity on the gap radius have been obtained and explained.