Increasing the Efficiency of Food Material Cutting during Inclined and Shear Movements of Knife

Mathematical models for predicting the resistance forces that are developed during the inclined and sliding cutting of food materials have been developed. The dependence of the actual cutting angle on the angle of inclination and sliding speed of the cutting edge at various sharpening angles have been investigated. For the inclined cutting mode, the dependence of the useful resistance force on the cutting speed has been determined at various angles of inclination of the cutting edge and designed sharpening angles. For the sliding cutting mode, the dependence of the useful resistance force on the feeding speed has been demonstrated at various sliding speed values and designed knife sharpening angles. The dependence of the transformed dimensionless sharpness of the knife on the angle of inclination of the cutting edge and the sliding speed has been established for different constructional sharpness values of the knife. The results of the study indicate that the useful resistance force is significantly reduced during the inclined and sliding cutting processes when compared with the normal cutting process, and a change in the pattern of fiber destruction, which significantly increases the cutting efficiency of cutting tools, is obtained.

Police Use of Force Escalation and De-escalation: The Use of Systematic Social Observation With Video Footage

As police agencies continue to incorporate body-worn cameras, it becomes increasingly important for researchers and practitioners to explore how to best use these data to better understand patterns of suspect and police behavior. Thus, drawing on a joint project between the Federal Law Enforcement Training Centers and Arizona State University, we expand on prior research demonstrating how social systematic observation (SSO) can be used with video footage to methodically detail the evolving nature of police-suspect encounters. We then illustrate how the data could be evaluated within the framework of escalation and de-escalation using an expanded version of the Resistance Force Comparative Scale (RFCS) first developed and employed in 2001. Finally, we assess the merits and challenges of using video footage to account for suspect and police behaviors in relation to escalation and de-escalation.

The Resistance Force of the Anterior Cruciate Ligament during Pull Probing Is Related to the Mechanical Property

There are various methods for reconstructing the anterior cruciate ligament (ACL) from other muscles or tendons. Initial tension of the reconstructed ACL is one of the key elements affecting postoperative outcomes. However, tension cannot be measured after graft fixation. The only intraoperative assessment is pull probing, which is performed by pulling joint soft tissues with the arthroscopic probe and can be measured quantitatively. Therefore, its value might be used as an alternative value for the mechanical property of the ACL. Using a probing device one author developed to measure the resistance force of soft tissues quantitatively while probing, we measured the resistance force of dissected ACLs and used tensile testing to investigate the correlation between the resistance force and the mechanical property of the ligaments. According to the results, when a certain amount of tension (strain; 16.6%) was applied, its mechanical properties were moderately correlated (r = 0.56 [p = 0.045]) with the probing force. Therefore, the tension of the reconstructed ACL after fixation under real ACL reconstruction surgery can be derived from the value of the probing device.

Getting the ducks in a row

Vessels – in the widest sense – travelling on a water surface continuously do work the water surrounding it, causing energy to be radiated in the form of surface waves. The concomitant resistance force, the wave resistance, can account for as much as half the total drag on the vessel, so reducing it to a minimum has been a major part of ship design research for many decades. Whether the ‘vessel’ is an ocean-going ship or a swimming duckling, the physics governing the V-shaped pattern of radiated waves behind it is in essence the same, and just as fuel economy is important for commercial vessels, it is reasonable to assume that also swimming waterfowl seek to minimise their energy expenditure. Using theory and methods from classic marine hydrodynamics, Yuan et al. (J. Fluid Mech., vol. 928, 2021, R2) consider whether, by organising themselves optimally, ducklings in a row behind a mother duck can reduce, eliminate or even reverse their individual wave resistance. They describe two mechanisms which they term ‘wave riding’ and ‘wave passing.’ The former is intuitive: the ducklings closest to the mother can receive a forward push by riding its mother's stern waves. The latter is perhaps a more striking phenomenon: when the interduckling distance is precisely right, every duckling in the row can, in principle, swim without wave resistance due to destructive wave interference. The phenomenon appears to be the same as motivates the recent US military research project Sea Train, a row of unmanned vehicles travelling in row formation.

Simulation of а car parameters impact on the process of its acceleration

Goal. The purpose of the work is mathematical modeling of Daewoo Lanos passenger car acceleration dynamics. Methodology. The mathematical model is based on the methodology of E.A. Chudakov and N.A.Yakovlev. According to this method, the main factor that determines the current value of vehicle acceleration at an elementary speed section is the dynamic factor. This factor depends on the traction force, the air resistance force and the weight of the vehicle. The paper proposes formulas for determining the dynamic factor and parameters of vehicle acceleration at an elementary speed section, where gear shift takes place. The model is implemented in the MATLAB software environment. The software product allows to determine the parameters of the car during acceleration to the maximum speed when the engine is running at the external speed characteristic modes. Results Based on the results of mathematical modeling for the Daewoo Lanos car, the loads arising in the drive of the car were analyzed. It is shown that the tractive effort is mainly spent on overcoming the inertial forces, which at the beginning of the movement exceed the resistance forces of the road and air by more than 50 times. With an increase in the vehicle speed, the inertia force decreases and at a speed of 100 km / h it is only twice the other load components. It is shown that with the accepted initial data, the Daewoo Lanos car accelerates to 100 km/h in 17.7 s, which corresponds to the experimental data. The influence of the mass of the car, the rated power of the engine, the mode and time of gear shifting, the radius of the wheels, the height of the car, the coefficient of aerodynamic drag on the dynamics of acceleration of the car is analyzed. It was revealed that the vehicle weight and the nominal power of the engine affect the dynamics of acceleration from 0 to 100 km/h to the greatest extent. The influence of other parameters in the indicated speed range is not somewhat significant. The explanation of the obtained results is given. Practical value. The mathematical model presented in the work allows to determine the parameters of the engine and the car during acceleration, take into account the influence of the design and adjusting parameters of the engine and the car on these indicators, and carry out optimization studies.

Research on the Controlling Effect of NPR Cables for Anti-Dip Slope Based on the Numerical Simulation

As the scale and depth of mines increase, large deformations of high-steep slopes progressively become prominent. Compared with the ordinary cables, negative Poisson’s ratio (NPR) cables can provide a constant resistance force and high deformation inhibition during slope deformation, avoiding the occurrence of slope instability hazards. Consequently, the control effects on the toppling failures of slopes were necessary to be researched. Changshanhao open-pit gold mine was taken as an example; based on the field geological investigation and rock mechanics testing, a three-dimensional engineering geological model of open-pit mine was constructed. Subsequently, the stability of open pit in current situation and final boundary situation was estimated with FLAC3D software, for the potential slope vulnerable areas to be comprehensively identified. Finally, the control effects of ordinary cables and NPR cables on the instable W13 slope section were compared and studied through FLAC3D simulations, and the reinforcement effects of NPR cable on the anti-dip slope were proved as significant; meanwhile, the corresponding reinforcement methods in the failure mine areas were proposed, laying a reference for the instability failure control and reinforcement of similar anti-dip slopes.

Numerical study on a rotational hydraulic damper with variable damping coefficient

The rotational hydraulic damper has advantages in the design and control of rotational machines. This paper presents a novel hydraulic rotational damper with the characteristic of adjusting the damping coefficient. It is composed of a shell, a gap, a rotor shaft, sliding vanes, a valve, and a motor, just like a combination of a sliding pump system and a valve driven by a motor. A new cam ring slot designed to guide the radial motion of sliding vanes could reduce friction resistance force, which will also benefit the design of the sliding pump. The damping coefficient model of this damper is established based on dynamic analysis. Series of numerical simulations validate the impact of factors on the damping coefficient. Frictional resistances have little influence on the damping coefficient during most conditions. The total coefficient is positively correlative with the angular velocity and the valve angle. Therefore, changing the valve angle according to the rotor shaft’s angular speed could adjust the damping coefficient.

Signal conditioning circuit for gel strain sensors

Conductive Hydrogels are soft materials which have been used by some researchers as resistive strain sensors in the last years. The electrical resistance change, when the sensor is stretched or compressed, is usually measured by the two-electrode method. This method is not always suitable to measure the electrical resistance of polymers-based materials, like hydrogels, because it could be highly influenced by the electrode/sample interface, as explained in this study. For this reason, a signal conditioning circuit, based on four-electrode impedance measurements, is proposed to measure the electrical resistance change when the gel is stretched or compressed. Experimental results show that the tested gels can be used as resistance force/pressure sensors with a quite linear behaviour.

TNT equivalent of the shock wave energy generated during the supersonic flight of an aircraft

To assess the impact on human health of the sonic boom that occurs when an aircraft is flying at supersonic speed, and, accordingly, to solve the problem of noise reduction by optimizing the aircraft design, it is proposed to evaluate the shock wave energy using the TNT equivalent of a cylindrical explosion. An example of calculating the shock wave energy during flights of F4 and F18 aircraft at different altitudes is considered. To calculate the evolution of an acoustic pulse during its propagation from the boundary of the shock wave transition to the acoustic one, the wave equation and its solution are used, taking into account the inhomogenei-ty of the atmosphere, nonlinear effects, absorption and expansion of the wave front, as well as the results of ground-based measurements of acoustic pulses. The results of calculations of the dependence of the explosion energy on the flight altitude, as well as on the type of aircraft are explained on the basis of the formula for the atmospheric resistance force.

Method for investigating rarefied gas flow around a cylindrical surface at arbitrary Knudsen numbers

A moment method for solving the linearized kinetic Boltzmann equation for arbitrary Knudsen numbers is presented. The isothermal flow of a rarefied gas around a cylindrical surface (the limiting cylindrical Couette problem) is investigated. The moments of the collision integral are calculated for the hard sphere model. The moment of resistance force acting per unit length of the surface, the profile of the gas flow velocity in the transient regime, and the gas velocity on the surface are calculated.