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It is important to study the theory and technology of coal-based oil shale dry beneficiation in China. Traditional separation density models are obtained through particle force analysis, but most studies tend to ignore the influence of medium resistance and bubble disturbance, which seriously limit the predicted accuracy of the separation density model. Therefore, the force on simulated mineral particles (steel balls) in pulsed fluidized bed (PFB) under different operating conditions was tested. It was found that the force decreases with the increase of gas velocity and distance from the distributor. The change of pulsation frequency has less influence on force. The force equilibrium equation was established and verified to be within 10% error; Finally, we obtain a new separation density model of PFB. This is of great importance for the industrialization and scale-up of dry beneficiation. [ABSTRACT FROM AUTHOR]

The aim of this study was to perform a validation of the Aquanex system to assess in-water forces during aquatic exercise. One sensor (Type A) that composes the differential pressure system (Aquanex v.4.1, STR, USA) was placed inside a wind tunnel (Axial Propellor Fan, England), this last being considered as the gold standard technique for measurement. A frequency inverter was used to control a range of twenty-two frequencies. The mean force (FMEAN, N) acting on the sensor and in the wind tunnel model was measured. The validation criteria were defined as follows: (i) p>0.05 in a paired t-test; (ii) R2≥0.49 in a simple linear regression model; and (iii) at least 80 % of the plots within the limits of agreement in the Bland-Altman plots. The results showed no differences between both methods (p=0.884). A significant relationship with a high effect (R2=0.573, p

This study aims to analyze the forces acting on the organs from the bolus during swallowing, excluding direct organ contact forces. We simulated the swallowing process of healthy individuals ingesting thickened non-Newtonian foods using a swallowing simulator based on the moving-particle simulation method. The force vectors acting on the organs and the bolus shape were extracted at each time interval. A twodimensional graph matrix was developed to visualize the temporal and spatial relationships between force and time for comprehensive interpretation and discussion. The graph matrix revealed that the bolus originated from tongue movement and was transferred between the oral cavity and pharynx, with coordinated movements of each organ occurring in pairs with balanced forces of the tongue and other organs. Information on the organ forces may offer a novel perspective for interpreting conventional mechanical indicators such as high-resolution manometry or tongue-pressure measurements. [ABSTRACT FROM AUTHOR]

The study aimed at the simple prediction problem of finite soil pressure for a new foundation pit adjacent to an existing subway station. Failure modes of the finite soil were proposed. Considering the friction between the soil and the structural interface, the formulas for calculating the finite soil pressure were derived with the horizontal differential element method, and the distribution was discussed. Furthermore, a simple calculation method for the resultant force of the finite soil pressure and the height of the action point was proposed with the principle of area equivalence. With the example and model tests, the rationality of the above method was verified. The influences of parameters on the resultant force of the soil pressure and the relative height of the resultant force were analyzed. The main conclusions are as follows: (1) The finite soil pressure has a nonlinear distribution and is lower than the conventional soil pressure. (2) Compared with other existing methods and model test results, the proposed finite soil pressure calculation method and simplified method are rational. (3) The finite soil pressure increases with the ground overload and soil weight and decreases with the internal friction angle and the structure-soil friction angle. (4) The relative height of the resultant force of the finite soil pressure increases with the structure-soil friction angle and decreases with the internal friction angle. (5) The proximity and covering soil thickness of the existing subway station have a lesser influence on the finite soil pressure, whereas the internal friction angle, weight, structure-soil friction angle and ground overload have a greater influence on the finite soil pressure. (6) The structure-soil friction angle has a greater influence on the height of the action point. The height of the resultant force is one-third of the enclosure structure depth if the structure-soil friction angle is 0. [ABSTRACT FROM AUTHOR]

The engineering application of vibration synchronization of multiple eccentric rotors (ERs) with the same rotational plane in far resonance is limited due to the constraints of motion characteristics and resultant force cancellation. Therefore, a dynamic model of four ERs distributed in two orthogonal planes is proposed in this paper, which is designed to increase the excitation force and drive the vibrating body to achieve the motion in a straight line. Based on the governing equation corresponding to the dynamic model firstly, the synchronous condition of four ERs and its stability condition are deduced. Then, the phase relationship of four ERs is obtained by numerical analysis, and the resultant force of four ERs in each phase difference is further studied to determine the motion trajectory of the vibrating body. Lastly, theoretical results are verified by four sets of experiments, which show that there are two stable motion states of the system. In each motion state, the resultant force of four ERs is increased compared to two ERs, and the system also moves in a straight line. Therefore, the model presented in this paper can provide a theoretical basis for designing large vibration machinery. • A new model of a single mass body excited by four orthogonally mounted eccentric rotors is explored. • The system exhibits two different linear motion states at far resonance, and there are multiple equilibrium points. • The model solves the problem of resultant force cancellation of multiple eccentric rotors in far resonance. [ABSTRACT FROM AUTHOR]

Background: Meniscal extrusion/translation has been used as an index for meniscal treatment. However, the relationship between meniscal displacement and the degree of meniscal tear or load–transmission function of the lateral meniscus (LM) remains unclear. Purpose: To clarify the relationship between the width of the radial tear of the LM and (1) meniscal displacement or (2) resultant force through the meniscus under axial compressive load in the porcine model. Study Design: Controlled laboratory study. Methods: Eight intact porcine knees with or without a partial radial tear at the midbody of the LM (involving 30%, 60%, or 90% of its width) were investigated. Reflective markers were attached to the outer wall of the anterior, anteromiddle, posteromiddle, and posterior segments of the LM. A 300-N axial load was applied at 2 flexion angles (30° and 60°), and the 3–dimensional forces and trajectories of the knees were recorded. Marker movements were simultaneously tracked using a motion capture camera system. After total meniscectomy of the LM, the recorded knee trajectories were reproduced, and the resultant force through the LM was calculated (a force carried only by the meniscus in response to a load applied to the whole knee joint). Results: At both flexion angles, the change in distance (mean ± SD) between the anterior and posterior markers under load increased significantly more in the anteroposterior direction in LMs with a 90% tear than in intact LMs (30°, 0.4 ± 0.3 vs 1.4 ± 0.8 mm, P =.004; 60°, 0.1 ± 0.7 vs 1.4 ± 1.0 mm, P <.001 [intact vs 90% tear]). The change in distance between the anteromiddle and posteromiddle markers at 30° also significantly increased in LMs with a 90% tear (0.2 ± 0.2 vs 1.3 ± 1.2 mm, P =.02 [intact vs 90% tear]). The resultant force was significantly lower in LMs with a 90% tear than in intact LMs (30°, 125 ± 47 vs 48 ± 20 N, P <.001; 60°, 93 ± 46 vs 43 ± 11 N, P =.002 [intact vs 90% tear]). We found no significant differences in either meniscal displacements or resultant forces between intact LMs and those with 30% or 60% tears. Conclusion: LMs with a 90%-width midbody radial tear lost load–transmission function with their displacement relative to the tibia primarily in the anteroposterior direction in the porcine model. Clinical Relevance: Even 1 mm of displacement after meniscal injury is evidence that the load–transmission function of the meniscus is greatly impaired. When a displaced torn LM is diagnosed in preoperative imaging, meniscal repair surgery should be considered. [ABSTRACT FROM AUTHOR]

The study aimed at the simple prediction problem of finite soil pressure for a new foundation pit adjacent to an existing subway station. Failure modes of the finite soil were proposed. Considering the friction between the soil and the structural interface, the formulas for calculating the finite soil pressure were derived with the horizontal differential element method, and the distribution was discussed. Furthermore, a simple calculation method for the resultant force of the finite soil pressure and the height of the action point was proposed with the principle of area equivalence. With the example and model tests, the rationality of the above method was verified. The influences of parameters on the resultant force of the soil pressure and the relative height of the resultant force were analyzed. The main conclusions are as follows: (1) The finite soil pressure has a nonlinear distribution and is lower than the conventional soil pressure. (2) Compared with other existing methods and model test results, the proposed finite soil pressure calculation method and simplified method are rational. (3) The finite soil pressure increases with the ground overload and soil weight and decreases with the internal friction angle and the structure-soil friction angle. (4) The relative height of the resultant force of the finite soil pressure increases with the structure-soil friction angle and decreases with the internal friction angle. (5) The proximity and covering soil thickness of the existing subway station have a lesser influence on the finite soil pressure, whereas the internal friction angle, weight, structure-soil friction angle and ground overload have a greater influence on the finite soil pressure. (6) The structure-soil friction angle has a greater influence on the height of the action point. The height of the resultant force is one-third of the enclosure structure depth if the structure-soil friction angle is 0.

Purpose. The main purpose of the article is to determine the permissible speed of the air-cushioned tilting train in curved track and to justify the expediency of operating this type of rolling stock on the railways of Ukraine to increase the speed, improve the passenger comfort and save the energy due to more uniform high-speed train driving.Methodology. The determination of the maximum permissible speed of the tilted train in curved track involves the use of methods of linear and vector algebra and empirical formulas for applied scientific and technical research. The calculation of the maximum speed is based on the principle of calculating centrifugal force for the velocities that meet the safety criteria of movement on the horizontal unbalanced acceleration in the stable radius curve. Findings.The results of the calculations showed that in the 1000 m radius curved track section, provided the passenger comfort, the maximum permissible speed of the train without forced tilt is 132 km/h, and with the forced tilt – 189 km/h. The velocity gain in the curve is about 30% and up to 10% on the section (depending on the number of curves). Originality.The method of determining the permissible speed of the tilted train in curved track is improved, which consists in determining the permissible centrifugal force acting on the train in the stable radius curve, taking into account the passenger comfort conditions. Practical value.This method allows accurately determining the permissible speed on the condition of passenger comfort in the curved section and the required additional tilt angle of the train, depending on the speed, curve radius and canting. Enhanced speed and comfort of passenger trains in the future will increase the demand for rail services among the population and strengthen the position of rail transport in Ukraine’s transport system.