Optimal Angular Velocity Research Articles

A Novel Size-Based Centrifugal Microfluidic Design to Enrich and Magnetically Isolate Circulating Tumor Cells from Blood Cells through Biocompatible Magnetite-Arginine Nanoparticles.

This paper presents a novel centrifugal microfluidic approach (so-called lab-on-a-CD) for magnetic circulating tumor cell (CTC) separation from the other healthy cells according to their physical and acquired chemical properties. This study enhances the efficiency of CTC isolation, crucial for cancer diagnosis, prognosis, and therapy. CTCs are cells that break away from primary tumors and travel through the bloodstream; however, isolating CTCs from blood cells is difficult due to their low numbers and diverse characteristics. The proposed microfluidic device consists of two sections: a passive section that uses inertial force and bifurcation law to sort CTCs into different streamlines based on size and shape and an active section that uses magnetic forces along with Dean drag, inertial, and centrifugal forces to capture magnetized CTCs at the downstream of the microchannel. The authors designed, simulated, fabricated, and tested the device with cultured cancer cells and human cells. We also proposed a cost-effective method to mitigate the surface roughness and smooth surfaces created by micromachines and a unique pulsatile technique for flow control to improve separation efficiency. The possibility of a device with fewer layers to improve the leaks and alignment concerns was also demonstrated. The fabricated device could quickly handle a large volume of samples and achieve a high separation efficiency (93%) of CTCs at an optimal angular velocity. The paper shows the feasibility and potential of the proposed centrifugal microfluidic approach to satisfy the pumping, cell sorting, and separating functions for CTC separation.

Spontaneous demixing of chiral active mixtures in motility-induced phase separation

The demixing and sorting strategies for chiral active mixtures are crucial to the biochemical and pharmaceutical industries. However, it remains uncertain whether chiral mixed particles can spontaneously demix without the aid of specific strategies. In this paper, we investigate the demixing behaviors of binary mixtures in a model of chiral active particles to understand the demixing mechanism of chiral active mixtures. We demonstrate that chiral mixed particles can spontaneously demix in motility-induced phase separation (MIPS). The hidden velocity alignment in MIPS allows particles of different types to accumulate in different clusters, thereby facilitating separation. There exists an optimal angular velocity or packing fraction at which this separation is optimal. Noise (translational or rotational diffusion) can promote mixture separation in certain cases, rather than always being detrimental to the process. Since the order caused by the hidden velocity alignment in this process is not global, the separation behavior is strongly dependent on the system size. Furthermore, we also discovered that the mixture separation caused by MIPS is different from that resulting from explicit velocity alignment. Our findings are crucial for understanding the demixing mechanism of chiral active mixtures and can be applied to experiments attempting to separate various active mixtures in the future.

Improving the energy efficiency of wind turbines for charging batteries

The article describes the method for determining the optimal angular velocity and the number of turns of the generator winding on permanent magnets powered by a wind turbine operating in specific operating conditions according to the wind speed regime. The optimization criterion is the maximum potential of energy that can be used to charge the battery. The permissible power of the generator and wind turbine, current and battery charging voltage are accepted as limiting factors. The restriction is provided by connecting a ballast resistor to the generator output. The power developed by the turbine is determined taking into account the wind energy utilization factor, which depends on the angular velocity of its shaft and wind speed. Two variants of power limitation are compared: by limiting the angular velocity by aerodynamic means and by stopping the wind turbine. The return of energy to charging in both cases is determined taking into account the distribution of wind speeds, obeying the Weibull probability distribution law. As an example, the calculation of the possible annual power generation for charging a battery with a capacity of 200 A∙h with a voltage of 24 volts from a synchron generator with a number of poles of 48 driven by a wind turbine with a radius of 2 meters, operating in an area with an average wind speed of 5 m/s. The calculation shows that for the parameters and operating conditions of the electrical installation used in the example, the maximum annual energy output (3.3 × 103 kWh) is observed at optimal 11 turns of the winding at each of the poles of the generator. The deviation of the number of turns from the optimal one in both directions by 2 times leads, with the same dimensions of the wind turbine, to a decrease in annual energy output by 3...5 times, which is a clear proof of the need to carry out such a calculation for each specific wind turbine.

Cascaded Model Predictive Control of a Tandem-Rotor Helicopter

This letter considers cascaded model predictive control (MPC) as a computationally lightweight method for controlling a tandem-rotor helicopter. A traditional single MPC structure is split into separate outer and inner-loops. The outer-loop MPC uses an SE2(3) error to linearize the translational dynamics about a reference trajectory. The inner-loop MPC uses the optimal angular velocity sequence of the outer-loop MPC to linearize the rotational dynamics. The outer-loop MPC is run at a slower rate than the inner-loop allowing for longer prediction time and improved performance. Monte-Carlo simulations demonstrate robustness to model uncertainty and environmental disturbances. The proposed control structure is benchmarked against a single MPC algorithm where it shows significant improvements in position and velocity tracking while using significantly less computational resources.

Investigation of anode shaping process during co-rotating electrochemical machining of convex structure on inner surface

A novel co-rotating electrochemical machining method is proposed for fabricating convex structures on the inner surface of a revolving part. The electrodes motion and material removal method of co-rotating electrochemical machining are different from traditional electrochemical machining. An equivalent kinematic model is established to analyze the novel electrodes motion, since the anode and cathode rotate in the same direction while the cathode simultaneously feeds along the line of centres. According to the kinematic equations of the electrodes and Faraday’s law, a material removal model is established to simulate the evolution of the anode profile in co-rotating electrochemical machining. The simulation results indicate that the machining accuracy of the convex structure is strongly affected by the angular velocity ratio and the radius of the cathode tool. An increase of the angular velocity ratio can improve the machining accuracy of a convex structure. A small difference in the radius of the cathode tool will cause changes in the shape of the sidewalls of the convex structure. The width of the cathode window affects only the width of the convex structure and the inclination α of the sidewall. A relation between the width of the cathode window and the width of the convex structure was obtained. The formation process for a convex structure under electrochemical dissolution was revealed. Based on the simulation results, the optimal angular velocity ratio and cathode radius were selected for an experimental verification, and 12 convex structures were simultaneously fabricated on the inner surface of a thin-walled revolving part. The experimental results are in good agreement with the simulation results, which verifies the correctness of the theoretical analysis. Therefore, inner surface co-rotating electrochemical machining is an effective method for fabricating convex structures on the inner surface of a revolving part.

NUMERICAL SIMULATION OF THE BROKEN ROCK MASS TRANSPORTATION IN A ROTATING PIPELINE

The impact of the angular velocity of a horizontal pipe rotating around its longitudinal axis and the shape of its cross-section on the efficiency of pneumatic conveying of bulk material in it has been numerically investigated by the discrete elements method. The maximum number of non-contact particles, that is, particles being not in contact with other material particles and with the pipe, in the cross section of the pipe during one its revolution, is assumed the condition for effective pneumatic conveying. A method for searching for non-contact particles is proposed, which makes it possible to calculate their number at fixed pipe position angles during its rotation. For various cross-sectional shapes, the optimal angular velocities are determined at which the average number of non-contact particles in the cross-section is maximum. The results of the study can be used to increase the productivity of the removal of products of destruction when drilling horizontal boreholes in rocks and soils.

Soft Sensor Simulation of Minimum Energy Consumption of Joint Manipulator Drive System Based on Improved BP Neural Network

The energy dissipation level of articulated mechanical arms directly affects the control stability of industrial robot systems. For a six-degree-of-freedom articulated robot driven by a DC servo motor and reduction gear, based on the Hamiltonian and Minimum theories, a model of the articulated manipulator drive system under load torque is established, and the expressions of optimal angular velocity and control current are obtained considering the viscous friction and coulomb factors. According to the analysis of actual parameter simulation experiments, it can be seen that the energy consumption of the joint manipulator drive system increases with the decrease of efficiency, the increase of the coulomb friction torque of the servo motor, and the increase of the load torque. Within the transit time, the total energy consumption of the drive system is smaller, so it is very important to obtain the transit time within the optimal area for the minimum energy consumption of the joint robotic arm drive system. At the same time, a soft neural network model based on the improved BP neural network built on the neural network toolbox for the energy consumption of the articulated mechanical arm is established. Finally, the experimental platform of servo motor drive system is built and used for the experiment of servo motor drive, and the purpose of closed-loop control is also achieved. Through experimental analysis, it can be seen that the proposed soft sensor model of joint minimum energy consumption based on improved BP neural network can more accurately realize the energy consumption prediction under unknown angular displacement and unknown load, and provide a theoretical basis for joint energy monitoring.

Research on Pressure Stability Control of High-pressure Common Rail System Based on Differential Equation Optimization Model

To improve the accuracy of fuel injection in high-pressure common rail systems of diesel engine, a mathematical model based on differential equations was established in view of the process of fuel entering and ejecting the common rail pipe, and the pressure variation law under working condition in the common rail tube was simulated in this study. Aiming at reducing the fuel pressure fluctuations in the system, the optimal angular velocity of the cam in high-pressure pump is solved by binary search algorithm, and the optimal control strategies for maintaining the dynamic and stability of pressure are given as well. Numerical simulation results show that with the presented strategies precise control of the pressure can be achieved in the common rail system, helping to improve the efficiency of the diesel engines.

Optimization of angular velocity of drum mixers

Drum mixers ensure a high level of uniformity when mixing the components of feed additives. However, the issues on theoretical and experimental substantiation of the structural and kinematic parameters of drum mixers have not been scientifically explored in detail. The aim of this study is to improve the efficiency of producing feed mixtures by ensuring the optimal angular rotation velocity of a drum mixer.To determine the radial speed of a particle’s motion along a drum blade, we solved a homogeneous differential equation. The numerical value for angular velocity was determined by a computer simulation method. We experimentally studied the uniformity of redistribution of feed components in a mixture of fodder using the designed experimental drum mixer. The mixer included a chamber, a rectangular frame, a supporting frame, and a drive. The mixing chamber included a loading/unloading window with a closed lid. Radial blades were installed inside the chamber along its entire length and evenly along the perimeter.Experiments were conducted using a drum mixer with a drum radius of 0.17 m, which included radial blades with a width of 25 mm, with a chamber’s fill factor of 0.5. It was established that the drum mixer ensures the maximum scattering of a material’s particles on the surface of the working segment at the drum’s angular rotation velocity of 9.69 rad/s.The results of experimental research have established that at rotation frequency of the laboratory plant’s drum of 9.42 rad/s the uniformity of mixture is 92.5‒93 %, which meets acting zootechnical requirements for all types of mixed fodder. In this case, a maximum deviation of the theoretical and experimental data was about 9 %. The results obtained suggest the possibility of determining a numerical value for the angular velocity of drum mixers by using the proposed method of computer simulation.

Application of the dynamic programming method to obtain of the angular velocity control law of a spacecraft with a small geometric asymmetry in the atmosphere

The atmospheric descent of a spacecraft with a small geometric asymmetry is considered. A quasi-linear dynamic system describes the motion of a spacecraft relative to the center of mass. The aim of the paper is to obtain the approximate optimal angular velocity control law, taking into account the change of the geometric asymmetry. We apply the method of dynamic programming and the non-resonant scheme of the averaging method for the synthesis of the optimal control law. Numerical results confirm the effectiveness of the obtained approximate law for optimal control of the angular velocity with respect to the problem of descent of the spacecraft with a small geometric asymmetry in the Martian atmosphere.

Algorithm of the Time-Optimal Reorientation of an Axially Symmetric Spacecraft in the Class of Conical Motions

The problem of the time-optimal turn of a spacecraft as a rigid body with one axis of symmetry and bounded control function in absolute value is considered in the quaternion statement. For simplifying problem (concerning dynamic Euler equations), we change the variables reducing the original optimal turn problem of axially symmetric spacecraft to the problem of optimal turn of the rigid body with spherical mass distribution including one new scalar equation. Using the Pontryagin maximum principle, a new analytical solution of this problem in the class of conical motions is obtained. Algorithm of the optimal turn of a spacecraft is given. An explicit expression for the constant in magnitude optimal angular velocity vector of a spacecraft is found. The motion trajectory of a spacecraft is a regular precession. The conditions for the initial and terminal values of a spacecraft angular velocity vector are formulated. These conditions make it possible to solve the problem analytically in the class of conical motions. The initial and the terminal vectors of spacecraft angular velocity must be on the conical surface generated by arbitrary given constant conditions of the problem. The numerical example is presented. The example contain optimal reorientation of the Space Shuttle in the class of conical motions.

Methods for determining the maximum energy area for wind power turbine

The present paper analyses two control methods for wind power systems to achieve optimum performance in terms of energy. The load control methods at wind turbines (WT) to achieve optimal operation, is based on the fact that the energy captured by the wind energy depends significantly on the mechanical angular velocity (MAV). In order to perform a function in the maximum power point (MPP) area, the load on the electric generator (EG) is changed and the power given by the wind turbine estimated. The first method, known as the small perturbation method, is widely used, becoming classic. The second original method consists in determining the optimal angular mechanical velocity ωOPTIM, using a low power auxiliary wind turbine that operates without load, at maximum mechanical angular velocity ωMAX. This value of MAV takes into account the wind speed evolution in time. The method bases on the particularity of the ωOPTIM/ωMAX report that does not depend on the time variation of wind speed values and has a constant value for a given WT.

Relationship between cardiopulmonary responses and isokinetic moments: the optimal angular velocity for muscular endurance.

Most protocols for testing and rehabilitation for recovery and improvement of muscular endurance have been set at 180°/sec, 240°/sec, and 300°/sec. These protocols can cause confusion to clinical providers or other researchers. This study was aimed at investigating the optimal isokinetic angular speed for measuring or developing muscular endurance after assessing the relationship between cardiopulmonary responses and isokinetic moments. This study was conducted with 31 male and female college students. Graded exercise test and body composition were measured as well as the isokinetic moments of the knee muscles at three angular speeds: 180°/sec, 240°/sec, and 300°/sec. The specific isokinetic moments of knee muscles that were measured included: peak torque (PT) and total work (TW) on extensor (e) and flexor (f) of knee joints, which were denoted as ePT180, fPT180, eTW180, fTW180, ePT240, fPT240, eTW240, fTW240, ePT300, fPT300, eTW300, and fTW300 according to the three angular speeds. Spearman correlation test was used to examine the relationship between the sum means of cardiopulmonary responses and the variables of isokinetic moments. This study confirmed that the optimal angular speed for testing or training for muscular endurance was 180°/sec, which showed a stronger relationship between cardiopulmonary responses and isokinetic moments. Therefore, this angular speed is recommended for testing and training for muscular endurance of the knee joints.

Time-averaged simulated microgravity (taSMG) inhibits proliferation of lymphoma cells, L-540 and HDLM-2, using a 3D clinostat

BackgroundGravity is omnipresent on Earth; however, humans in space, such as astronauts at the International Space Station, experience microgravity. Long-term exposure to microgravity is considered to elicit physiological changes, such as muscle atrophy, in the human body. In addition, certain types of cancer cells demonstrate inhibited proliferation under condition of time-averaged simulated microgravity (taSMG). However, the response of human Hodgkin’s lymphoma cancer cells to reduced gravity, and the associated physiological changes in these cells, have not been elucidated.MethodsIn this study, the proliferation of human Hodgkin’s lymphoma cancer cells (L-540 and HDLM-2) under taSMG condition (<10−3 G, 1 G is defined as 9.8 m/s2) was studied using a 3D clinostat. Normal human dermal fibroblast (HDF) was proliferated in the same condition as a control group. For the development of 3D clinostat, two motors were used to actuate the frames. Electrical wires for power supply and communication were connected via slip ring. For symmetrical path of gravitational vector, optimal angular velocities of the motors were found using simulation results. Under the condition of taSMG implemented by the 3D clinostat, proliferation of the cells was observed for 3 days.ResultsThe results indicated that proliferation of these cancer cells was significantly (p < 0.0005) inhibited under taSMG, whereas proliferation of normal HDF cells was not affected.ConclusionsFindings in this study could be significantly valuable in developing novel strategies for selective killing of cancer cells such as lymphoma.

Nonlinear Sagnac interferometer based on the four-wave mixing process.

A new nonlinear Sagnac interferometer (NSI) is proposed by replacing the beam-splitter in the traditional Sagnac interferometer (TSI) with a four-wave mixing process. Such a NSI has better angular velocity sensitivity than the one of the TSI. The standard quantum limit can be beaten and the Heisenberg Limit can even be reached for the ideal case by the NSI. We study the effect of the losses on the angular velocity sensitivity of the NSI and find that the optimal angular velocity, where the best angular velocity sensitivity can be obtained, of the NSI may be dependent on the losses inside the interferometer. Such a NSI has its advantages compared with the TSI and may find its potential applications in quantum metrology.

Performance investigation of an innovative vertical axis turbine consisting of deflectable blades

The aim of this study is to investigate the performance of an innovative vertical axis turbine which possesses the blade-self-deflection function for ocean current and tidal energy application. The blade deflection is accomplished by interaction of blades and related mechanisms as the turbine rotates. To enhance the turbine performance, it is designed that the blade deflection not only increases the power output for a downstream blade, but also decreases the resistance for an upstream blade. The observation of the prototype in laboratory flume is displayed to validate the feasibility. Furthermore, a commercial code is employed to analyze the turbine performance. The velocity and pressure contours of the calculation domain are simulated to obtain the torque and power output of deflectable-blade turbine. Moreover, the results of performance analysis are validated by the experimental data.The detailed flow field analysis and hydrodynamic characteristic are reported as deflectable-blade turbine is driven by the water stream. The results show that the maximum and minimum total torque for this turbine occur at θ=45° and θ=75°, respectively as it rotates one-quarter turn. In performance comparison, the maximal power coefficient of the deflectable-blade turbine is 41.1% higher than that of traditional vertical axis turbine with fixed blades for stream velocity of 1m/s. Furthermore, the correlations of optimal angular velocity and maximal power output for the deflectable-blade turbine are obtained for current velocity from 0.6m/s to 2.2m/s for hydropower applications.

Particle motion around open mixing screws: optimal screw angular velocity

Purpose The analysis of the effect of screw angular velocity on the mixing efficiency of open mixing screws. Design/methodology/approach Measurements and discrete element method based simulations. Findings There is an optimal screw rotation angular velocity above which there is no reason to operate the mixing apparatus, as the mixing efficiency does not increase with the increase of screw angular velocity. Research limitations/implications By using discrete element method based optimization of open mixing screw apparatus, the effective mixing of agricultural grains can be achieved. The quality degradation of the dried product can be reduced. Practical implications The causeless increase of screw angular velocity results higher power consumption and quality degradation because of the increasing value of contact forces arising between the mixed particles. Originality/value Our article shows that by using discrete element based simulations, the optimal working parameters of open mixing screws can be evaluated.

Алгоритм оптимального по энергии разворота космического аппарата при произвольных граничных условиях

The problem of the optimal turn in the sense of minimal energy loss of a spacecraft as a rigid body with an arbitrary distribution of mass without constraint of a control action and under arbitrary boundary conditions is considered in the quaternion statement. In the class of the generalized conical motions a modification was made of the task of optimal rotation, which allowed to obtain analytical solution to the movement equations containing any constants and two any scalar functions (parameters of the generalized conic movement). Concerning these functions and their derivatives the optimizing problem with a square functionality, in which the second derivative of these two functions acts as control, was formulated and solved using Pontryagin maximum principle. Explicit expressions for the optimal angular velocity and the optimal control vectors of a spacecraft are presented. The motion trajectory of a spacecraft is generalized as a conical precession. Algorithm for the optimal turn of a spacecraft is given. The found analytical solution to the modified problem can be considered as an approximate solution to the classical problem of an optimal turn of a spacecraft under arbitrary boundary conditions. Numerical examples are presented showing that the solution of the modified problem well approximates the solution of the classical problem of a spacecraft optimal turn. These examples contain reorientations of the International Space Station and of the Space Shuttle.

Analysis and synthesis of sliding mode control for large scale variable speed wind turbine for power optimization

The problem of designing a nonlinear feedback control scheme for variable speed wind turbines, without wind speed measurements, in below rated wind conditions was addressed. The objective is to operate the wind turbines in order to have maximum wind power extraction while also the mechanical loads are reduced. Two control strategies were proposed seeking a better performance. The first strategy uses a tracking controller that ensures the optimal angular velocity for the rotor. The second strategy uses a Maximum Power Point Tracking (MPPT) algorithm while a non-homogeneous quasi-continuous high-order sliding mode controller is applied to ensure the power tracking. Two algorithms were developed to solve the tracking control problem for the first strategy. The first one is a sliding mode output feedback torque controller combined with a wind speed estimator. The second algorithm is a quasi-continuous high-order sliding mode controller to ensure the speed tracking. The proposed controllers are compared with existing control strategies and their performance is validated using a FAST model based on the Controls Advanced Research Turbine (CART). The controllers show a good performance in terms of energy extraction and load reduction.

On optimal spacecraft damping

The problem of spacecraft damping (damping of initial angular velocity to zero) for a minimal time is studied. Two variants of formulation of the optimization problem are considered; these variants differ in the form of constraints on the control torque. Analytical solution to the formulated problem is obtained in the closed form and numerical expressions for synthesis of optimal angular velocity control program are given. Similar problem of time-optimal angular acceleration of the spacecraft to the given value is also solved. Procedure for determination of the control torque at the initial time instant for the problem of acceleration of the spacecraft to the required angular velocity is presented. Numerical example of solution of the problems of buildup and damping of spacecraft rotation velocity for a minimal time is given.