Surface exploration in virtual reality has a large potential to enrich the user's experience. It could for example be used to train and simulate medical palpation. During palpation, users tap, ...indent, and rub the surface of a sample to estimate the underlying properties. However, up to now there is no good approach to render such intricate interaction realistically. This paper introduces 6 degrees of freedom (DoF) encountered-type haptic display technology for simulating surface exploration tasks. Among the different phases of exploration, this article focuses on the 'in-contact sliding' phase. Two novel control approaches to render sliding over a virtual surface are elaborated. A first rendering method generates lateral frictional forces as the finger slides over the surface. A second method adjusts the inclination of the end-effector to render tissue properties. With both methods a stiff nodule embedded in a soft tissue was prepared. User experiments were carried out to find proper parameter and intensity ranges and to confirm the feasibility of the new rendering schemes. Participants indicated that both rendering schemes felt realistic. Compared to earlier work, where only the vertical stiffness was altered, lower thresholds to detect and localise embedded virtual nodules were found. Users also made fewer errors in detecting nodule edges. Furthermore, the method that used end-effector inclination allowed faster discovery of the nodule's edges. It is expected that approaches that combine both rendering methods could provide an even more realistic feel.
This paper presents the results of laboratory tests that allowed us to determine the effect of the soil surface inclination and its initial moisture content on the formation of overland and ...subsurface runoff. The experiments were carried out for the soil that is commonly present in the southern part of Poland, including the Outer Carpathians. The results of these measurements served as a reference for overland runoff calculations using the Richards model, simplified Green–Ampt model, and the empirical model (MSME). The results of the measurements showed that, for low-permeable soil, overland runoff is the dominant form. It was shown that a slope in the range of 2.5–5.0% does not have a significant effect on the amount of overland runoff, but affects its dynamics. The measurements also showed that the starting time and amount of overland runoff are strictly associated with the initial soil moisture content. High soil moisture content in the period preceding the onset of rainfall causes faster generation and an increase in overland runoff, which is caused by the saturation of the surface layer of the soil. This mechanism was confirmed by the results of calculations using the Richards model and measurements of the electrical resistance of the soil. Theoretical calculations showed that the results of the runoff calculations using the Richards and Green–Ampt models are strongly dependent on the hydraulic properties of the soil adopted for the analysis. It was also demonstrated that the modified MSME model satisfactorily estimates the amount of overland and subsurface runoff, but requires parameter calibration based on existing hydrological data.
Abstract
In view of the large deformation in the roadway of layered surrounding rock, with W22602 return air roadway of Datong No.1 Mine as the engineering background, using the finite-difference ...software FLAC3D, we explored the influence of the angle of the bedding plane under the prestressed bolt support on the plastic zone and the stress and strain distribution law of the surrounding rock of the roadway, and analyzed the deformation and failure characteristics of the bedding plane under the action of the bolt. The results show that: with the increase of the inclination of the bedding plane, the horizontal and vertical deformation of the bedding plane first increase and then decrease, showing a “Λ”-shaped change characteristic; in horizontal layered surrounding rock, as the prestress of bolt support increases, the strength of the weak rock layer gradually increases, and the surface displacement of the bedding plane gradually decreases; the plastic zone of the surrounding rock with different dip angles has a significant “angle effect”, and the angle between the bolt and the bedding surface has a significant difference in the control effect of the bedding plane; based on the simulation results when the inclination angle is 15°, field practice is carried out. And it shows that the optimization scheme can improve the stability of the surrounding rock of the roadway more economically and effectively.
This work concentrates on the analysis of cutting forces and vibrations generated during ball end milling process with variable surface inclination angle (α). The cutting force and tool's ...displacements (vibrations) model including surface inclination was formulated. Experiments were carried out on hardened alloy steel X155CrVMo12-1 with sintered carbide (TiAlN coating) monolithic tool. Instantaneous values of cutting forces were measured in the range of variable feed per tooth (fz) and surface inclination angle (α) values. The shear (Kic) and edge (Kie) coefficients in function of analyzed factors were determined using the measured cutting force signals as an input data. The research revealed that cutting forces and vibrations are strongly affected by the surface inclination, both in quantitative and qualitative aspect. This observation is also confirmed by the developed model.
This paper reports a new method for calculating the active earth pressure acting on inclined rigid retaining wall with inclined backfill, considering wall-soil interface friction angle. Based on ...Mohr-Coulomb strength theory and Mohr stress circle, new formulae of the active earth pressure and the active rupture angle are derived. The effects of internal friction angle, backfill-surface inclination, wall-back inclination on the active earth pressure and the active rupture angle are investigated. In order to facilitate calculation, special solutions of presented formulae are discussed under various particular conditions. Finally, the calculated results from the presented formula and existing formulae are compared with existing small-scale test results. The comparison shows that the presented method satisfactorily predicts active earth pressure.
Investigated is the effect of inclination, from 0° (upward facing) to 180° (downward facing), on saturation nucleate boiling of degassed PF-5060 dielectric liquid on two Cu micro-porous surfaces ...measuring 10 × 10 mm, and 80- and 197-μm thick. These surfaces, deposited by electrochemical processes on Cu substrates of the same footprint area and 1.6 mm thick, are heated uniformly in the experiments. The high volume porosity and morphology of the surfaces enhance nucleate boiling by increasing the bubbles nucleation sites density and the wetted surface area. The measured CHF values and those of the maximum nucleate boiling heat transfer coefficient,
h
MNB, are much higher than measured on plane Cu and decrease monotonically with increased surface inclination to their lowest values in the downward facing orientation (180°). The 197-μm thick micro-porous surface gives the largest enhancements in CHF and
h
MNB.
► Experimental results of nucleate boiling enhancement on micro-porous copper surfaces. ► Results show significant enhancements compared to plane copper. ► Surface inclination decreases both the maximum nucleate boiling heat transfer coefficient and the critical heat flux.
In this research, a novel type of interface by seat surface inclination for electric wheelchair is developed in order to improve the current Joystick one. The sensibility evaluation experiments based ...on low and high velocities are carried out. By using the tilt sensor in this study, the data of cushion's inclinations are recorded to manipulate the wheelchair. The reformed wheelchair is evaluated by the SD method. 20 students are participated in the experiment which is executed in a room with 5m×5m size. The respondents answer the surveys after operating. First, the experiment results indicate that the interface form is feasible. The comments on the low velocity mode are relatively well among the two velocities. Compared with taking fully automatic ones, when the user is taking our developed wheelchair, the low velocity mode is preferred.
The movement of single air bubbles under a downward facing inclined solid surface has been investigated in motionless distilled water body. The effects of surface inclination
θ and bubble volume
V on ...the terminal Froude number are studied in details. The bubble volume was varied in the 0.3–9
cm
3 range and the inclination angles up to 10° in a gravity driven system. For a typical correlation curve of the terminal velocity
u
T versus the volume at a given inclination it was found that the increase of
u
T with
V is not monotonous and that four distinct sub-regimes, each characterized by a specific bubble shape, exist. The effect of inclination on
u
T is more sensitive at both low
V and low
θ. The different sub-regimes are explained qualitatively. In addition, the drag coefficients for moving bubble underneath a solid surface are presented.
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