Design and comparative analysis of self-propelling drill bit applied to deep-sea stratum drilling robot

Robotic subsea stratum drilling robot is a method for new subsea stratigraphic geological investigation and resource exploration.Resistance at the front end is the main source of resistance to the robot’s motion in the strata.Since there is no continuous and strong downward drilling force as in conventional drilling rigs,robot movement relies heavily on the drill bit to reduce the drilling resistance.In this study we propose a self-propelling drill bit that can discharge soil debris to provide propulsive force and reduce the resistance.The key parameter of the drill bit design,the spiral blade lead angle,was determined by theoretical analysis of the drill bit’s soil discharging effect.To verify the structural advantages of the self-propelling drill bit in reducing resistance,a comparative analysis with a conventional conical drill bit was conducted.The drilling process of both bits was simulated using finite element simulation at various rotation speeds,the penetration force and torque data of both drill bits were obtained,and tests prepared accordingly in subsea soil were conducted.The simulations and tests verified that the penetration force of the self-propelling drill bit was lower than that of the conventional conical drill bit.The self-propelling drill bit can reduce the resistance effectively,and may play an important role in the stratum movement of drilling robots.

Passive particles driven by self-propelled particle:The wake effect

This work focuses on numerically studying hydrodynamic interaction between a passive particle and a self-propelled particle,termed a squirmer,by using a two-dimensional lattice Boltzmann method(LBM).It is found that the squirmer can capture a passive particle and propel it simultaneously,provided the passive particle is situated within the squirmer's wake.Our research shows that the critical capture distance,which determines whether the particle is captured,primarily depends on the intensity of the squirmer's dipolarity.The stronger dipolarity of squirmer results in an increased critical capture distance.Conversely,the Reynolds number is found to have minimal influence on this interaction.Interestingly,the passive particle,when driven by the squirmer's wake,contributes to a reduction in the squirmer's drag.This results in a mutual acceleration for both particles.Our findings can provide valuable perspectives for formulating the principles of reducing the drag of micro-swimmers and help to achieve the goal of using micro-swimmers to transport goods without physical tethers.

Classifying wakes produced by self-propelled fish-like swimmers using neural networks

We consider the classification of wake structures produced by self-propelled fish-like swimmers based on local measurements of flow variables.This problem is inspired by the extraordinary capability of animal swimmers in perceiving their hydrodynamic environments under dark condition.We train different neural networks to classify wake structures by using the streamwise velocity component,the crosswise velocity component,the vorticity and the combination of three flow variables,respectively.It is found that the neural networks trained using the two velocity components perform well in identifying the wake types,whereas the neural network trained using the vorticity suffers from a high rate of misclassification.When the neural network is trained using the combination of all three flow variables,a remarkably high accuracy in wake classification can be achieved.The results of this study can be helpful to the design of flow sensory systems in robotic underwater vehicles.

Comparison of Microbubble and Air Layer Injection with Porous Media for Drag Reduction on a Self-propelled Barge Ship Model

Ship resistance issues are related to fuel economy,speed,and cost efficiency.Air lubrication is a promising technique for lowering hull frictional resistance as it is supposed to modify the energy in the turbulent boundary layer and thereby reduce hull friction.In this paper,the objective is to identify the optimum type of air lubrication using microbubble drag reduction(MBDR)and air layer drag reduction(ALDR)techniques to reduce the resistance of a 56-m Indonesian self-propelled barge(SPB).A model with the following dimensions was constructed:length L=2000 mm,breadth B=521.60 mm,and draft T=52.50 mm.The ship model was towed using standard towing tank experimental parameters.The speed was varied over the Froude number range 0.11–0.31.The air layer flow rate was varied at 80,85,and 90 standard liters per minute(SLPM)and the microbubble injection coefficient over the range 0.20–0.60.The results show that the ship model using the air layer had the highest drag reduction up to a maximum of 90%.Based on the characteristics of the SPB,which operates at low speed,the optimum air lubrication type to reduce resistance in this instance is ALDR.

A comparative study of the self-propelled jumping capabilities of coalesced droplets on RTV surfaces and superhydrophobic surfaces

Understanding the mechanism of coalescence-induced self-propelled jumping behavior provides distinct insights in designing and optimizing functional coatings with self-cleaning and anti-icing properties.However,to date self-propelled jumping phenomenon has only been observed and studied on superhydrophobic surfaces,other than those hydrophobic surfaces with weaker but fairish water-repellency,for instance,vulcanized silicon rubber(RTV) coatings.In this work,from the perspective of thermodynamic-based energy balance aspect,the reason that self-propelled jumping phenomenon does not happen on RTV coatings is studied.The apparent contact angles of droplets on RTV coatings can be less than the theoretical critical values therefore cannot promise energy surplus for the coalesced droplets onside.Besides,on RTV and superhydrophobic surfaces,the droplet-size dependent variation characteristics of the energy leftover from the coalescence process are opposite.For the droplets coalescing on RTV coatings,the magnitudes of energy dissipations are more sensitive to the increase in droplet size,compared to that of released surface energy.While for superhydrophobic coatings,the energy generated during the coalescence process can be more sensitive than the dissipations to the change in droplet size.

An Operational Modal Analysis Experimental Technique for Self-propelled Gun

The experimental modal analysis of the selected self-propelled gun was completed to obtain its modal frequency distribution and modes by using an operational modal analysis experimental technique.The result obtained by the method was compared with that obtained by the traditional method.It indicates that the two results are in good agreement.

Effect of the structure of backward orifices on thejet performance of self-propelled nozzles

Self-propelled nozzle is a critical component of the radial jet drilling technology.Its backward orifice structure has a crucial influence on the propulsive force and the drilling performance.To improve the working performance of the nozzle,the numerical simulation model is built and verified by the experimental results of propulsive force.Then the theoretical model of the energy efficiency and energy coefficient of the nozzle is built to reveal the influence of the structural parameters on the jet performance of the nozzle.The results show that the energy efficiency and energy coefficient of the backward orifice increase first and then decrease with the angle increases.The energy coefficient of forward orifice is almost constant with the angle increases.With the increase in the number and diameter,energy efficiency and energy coefficient of the forward orifice gradually decrease,but the backward orifice energy coefficient first increases and then decreases.Finally,it is obtained that the nozzle has better jet performance when the angle of backward orifice is 30°,the number of backward orifice is 6,and the value range of diameter is 2-2.2 mm.This study provides a reference for the design of efficiently self-propelled nozzle for radial jet drilling technology.

Nonvanishing optimal noise in cellular automaton model of self-propelled particles

A minimal cellular automaton model is introduced to describe the collective motion of self-propelled particles on two-dimensional square lattice. The model features discretization of directional and positional spaces and single-particle occupation on one lattice site. Contrary to the Vicsek model and its variants, our model exhibits the nonvanishing optimal noise. When the particle density increases, the collective motion is promoted with optimal noise strength and reduced with noise strength out of optimal region. In addition, when the square lattice undergoes edge percolation process, no abrupt change of alignment behaviors is observed at the critical point of percolation.

Ratchet transport of self-propelled chimeras in an asymmetric periodic structure

We studied the rectified transport of underdamped particles subject to phase lag in an asymmetric periodic structure.When the inertia effect is considered,it is possible to observe reversals of the average velocity with small self-propelled force,whereas particles always move in the positive direction with large self-propelled force.The introduction of phase lag leads particles to follow circular orbits and suppress the polar motion.In addition,this can adjust the direction of particle motion.There exists an optimal value of polar interaction strength at which the rectification is maximal.These results open the way for many application processes,such as spatial sorting of particles mixture and separation based on their physical properties.

Traction Potential Analysis of Self-Propelled Seafloor Trencher Based on Mechanical Measurements in Bentonite Soil

Shear stress-displacement relationship model of soil is very important to predict the tractive performance of tracked vehicle. Most shear stress-displacement models were proposed for terrestrial field.However,they are not suit for soft seafloor with flow surface and high water content. Based on comprehensive analysis of seafloor soil shear deformation and track segment shear tests,a new empirical model of shear stressdisplacement relationship for saturated soft-plastic soil(SSP model) was proposed. To validate the SSP model and evaluate potential tractive force of self-propelled seafloor trencher,a test platform,where track segment shear test and drawbar pull test can be performed in seafloor soil substitute(bentonite water mixture),was built. Series of shear tests were carried out. Test results show that the SSP model can describe the mechanical behavior of track segment in seafloor soil substitute with good approximation. Through analyzing the main external forces,including environmental loads from seafloor soil and sea current applied to seafloor tracked trencher during the trenching process in a straight line,drawbar pull analysis model was deduced with the SSP model. A scale test model of seafloor tracked trencher was built,and the verification tests for drawbar pull analysis model were designed and carried out. Results of verification tests indicate that the drawbar pull analysis model was feasible and effective. The drawbar pull tests also indicated that the SSP model is valid from another side.

Going in Homer:The Role of Verb-Inherent Actionality Within Self-Propelled Motion-Event Encoding

The paper aims at investigating the encoding of self-propelled motion events in Homeric Greek in the light of the typology of motion events,taking into account the case of to go.The verbal class of the self-propelled motion refers to those verbs expressing the idea of a simple translational motion,such as to go,to move,without any information about the manner of motion(see,by contrast,the class of the manner-of-motion verbs,such as to run,to swim)or about the path of motion(see,by contrast,the class of the path verbs,such as to enter,to exit).According to Talmy(2000),world languages can be distinguished depending on whether they prototypically express the semantic component of Path in or outside the motion verb.Languages belonging to the S(atellite)-Framed type tend to convey Path outside the motion verb,in a satellite element,such as a particle,an adposition(adpositional phrase),a preverb,an adverb(ial),a nominal case marker.The prototypical encoding pattern of the S-Framed languages,such as Homeric Greek,involves a motion verb conveying Manner and a satellite conveying Path,i.e.,[manner-of-motion verb+Path-satellite].Nonetheless,another pattern is used by this type of languages,albeit less prototypical,which involves a motion verb conveying only Motion and a satellite conveying Path,i.e.,[self-propelled motion verb+Path-satellite].Verb-inherent actionality,namely telicity,turns out to be a strong feature within the ancient Indo-European languages,such as Homeric Greek,playing a role not only in the development of aspectual/tense morphology,but also in the encoding of motion events,at least with reference to manner-of-motion verbs.The present paper aims at verifying the role of inherent telicity within self-propelled motion verbs,through the analysis of Homeric verbs for go.The study takes into account the Homeric suppletive paradigm for go,focusing on ερχομαι“go;come”and ηλθον(aorist)“go;come”(also with reference to the unclear actional opposition between ερχομαι and ειμι“go;come”).From the textual analysis of all the occurrences of both ερχομαι and ηλθον,as well as their co-occurring Path-encoding elements in the Iliad and the Odyssey,data show to what extent verbal inherent telicity plays an important role in motion event encoding also within the class of self-propelled motion verbs.

Deployment of Self-Propelled Modular Transporter for Vessel Installation

The traditional way of installing large vessels has always been to employ the use of cranes. The Water Handling Debottlenecking Project team has, instead, made use of a different technology—employing a Self-Propelled Modular Transporter (SPMT) to install nine vessels in situ. These SPMT units have many advantages over crane installations, such as safety and efficiency, not to mention lower costs due to their self-propelled capabilities.

Development and Evaluation of Self-propelled Cabbage/Cauliflower Harvester

In the present study,self-propelled cabbage/cauliflower harvester was designed,developed and evaluated.The machine consisted of different components like engine,frame,shearing(cutting)unit and power transmission unit.The power transmission unit consisted of main clutch,shearing blade operating clutch,belt drive unit,chain and sprocket drive,universal joint and cutter blade assembly.The main working principle of harvester is based on shearing of crop stem against high-speed rotating blade.The power from the engine is transmitted by belt-pulley drive unit to transmission shaft on which chain and sprocket is mounted on one side and then power is transmitted to shearing blade coupling with the help of a stationary pulley and fixed socket.Average mean head diameter of the selected cabbage and cauliflower was 89.5±15.24 mm and 107.5±15.24 mm,respectively.Average mean stem(plant)diameter of the selected cabbage and cauliflower was 18±4.85 mm and 21.5±3.08 mm,respectively.The shearing force increased with increase in diameter of stem.The optimum performance of the machine was achieved when it was operated at 1.5 km/h forward speed and the shearing blade moving at speed of 147 rpm.The mean field capacity for developed prototype was observed as 0.063 ha/h and 0.053 in case of cabbage and cauliflower,respectively with field efficiency of 91.97 and 90.48%.The average head damage was negligible(0.15%)for both the crops.The average untrimmed percentage with developed harvester was 3.2 and 3.0%in case of cabbage and cauliflower crop,respectively.The developed machine helps to increase the field capacity in cabbage/cauliflower harvesting due to 7-times more capacity and 50%cheaper compared to traditional method of cabbage/cauliflower harvesting.At the operating condition of forward speed(1.5 km/h)and shearing blade speed(147 rpm),the machine could harvest 0.5 ha of cabbage and 0.42 ha of cauliflower farm per day of 8-h.This same task would have required between 15 labour per day if entirely done manually.

Rectified transport of a single vibration-driven vehicle in the asymmetric channel

The rectification transport of a single vibration-driven self-propelled vehicle in a two-dimensional left–right asymmetric channel was experimentally investigated. The rectification efficiency of the vehicle moving from the center to the exit was statistically obtained for the range of channel widths, inter-channel asymmetry degrees, and platform tilt angles.The trajectory of its movement was also analyzed. It was found that the structure of the channel provides the main influence. Different channel shapes lead to different ranges of unfavorable widths, and transport efficiency decreases when the asymmetry diminishes—the two channels converge. The addition of external gravity does not counteract the structural limitations, but only affects the probability of departure.

Recent progress in self-propelled particles

Self-propelled particles are commonly found in a large number of planktonic organisms such as bacteria,fungi,and algae in nature,and researchers have taken a long interest in exploring their swimming mechanisms for more than a century.Especially in the past 20 years,with the development of computational fluid dynamics and flow display technology,as well as the need for the design of synthetic self-propelled particles and micro-swimming devices,self-propelled particles have become the forefront and hotspot of current research in the field of fluid mechanics.This paper first introduces the swimming characteristics of common self-propelled particles,leading to a classic“squirmer”type self-propelled particle model.On this basis,a systematic introduction and summary of the theoretical and numerical simulation research of“squirmer”will be conducted.Finally,the main challenges and opportunities faced by the current research will be summarized.

Influences of the tank liquid lateral sloshing and mass time-varying on high clearance self-propelled sprayer ride comfort

To explore the influence of the lateral sloshing and the time-varying mass of the liquid in the tank on the ride comfort of the high-clearance sprayer,a spring-mass-damping equivalent mechanics that can describe the lateral sloshing of the liquid under different filling ratios was constructed based on the equivalent criterion.The Fluent was used to simulate the moment acting on the wall of the tank by the lateral sloshing of the liquid,and then the parameters of the equivalent mechanical model are obtained by fitting and solving.Comparative analysis of Fluent simulation and bench test on lateral sloshing of tank liquid under different filling ratios.The results show that the lateral sloshing trend of the tank liquid level obtained from the Fluent simulation and the bench test was consistent,which proved the accuracy of the Fluent fluid simulation process and the correctness of the required equivalent mechanical model parameters.Incorporating a liquid sloshing equivalent model,a four-degree-of-freedom vertical dynamic model of the sprayer half-car was established.Subsequently,the performance of the sprayer was systematically analyzed and compared under the excitation of a bump road and a random E-level road.This investigation took into account varying liquid filling ratios of 10%,50%,and 90%.The focus lay on evaluating the vertical acceleration of the sprayer body,dynamic deflection of the suspension,and dynamic load on the tires in response to these road conditions.This analysis is conducted independently of the liquid sloshing factor.The results show that the lateral sloshing of the liquid medicine significantly reduces the ride smoothness of the machine,and makes the vibration response of the machine produce a certain hysteresis effect.With the reduction of the quality of the liquid medicine in the spray tank,the vibration amplitude of the sprayer body gradually decreases,the hysteresis effect is also gradually weakened.The results presented in this study offer a theoretical foundation for the analysis of ride comfort and the optimization of chassis structure in high-clearance sprayers.

Dual-Fuel-Driven Bactericidal Micromotor

In this paper, we report fabrication of the bimetallic Janus microsphere, a magnesium microsphere with a silver surface coating, through thermal evaporation technique. Because of the Janus structure, this micromotor can be propelled in two different directions by the surface silver or magnesium ‘engine' and hydrogen peroxide or water fuel. In addition, due to the bactericidal property of silver, this autonomous micromotor is capable of killing bacteria in solution. As compared to the static one, the micromotor is able to kill the bacteria at a much faster rate(about nine times of that of the static one),demonstrating the superiority of the motion one. We thus believe that the micromotor shown in the current study is potentially attractive for the environmental hygiene applications.

Optimal Guaranteed Cost Control Algorithm for Automatic Chain Shell Magazine

The automatic chain shell magazine is the primary subassembly of the automatic ammunition loading system of a big-caliber howitzer. Due to the change of the shell amount in the magazine during firing, its positioning control is a kind of control problem of systems with uncertain parameters. In order to realize accurate control of shell position, an optimal guaranteed cost control algorithm based on linear matrix inequality (LMI) theory was put forward. The motion equations of the magazine were built, and the motion equations for four special load situations were linearized; according to the basic theory of the guaranteed cost control, the motion equations were written as the standard forms for linear uncertain systems; the optimal guaranteed cost control law for the position control of the magazine was obtained by use of LMI toolbox in MATLAB package. Using this control law, the controlled dynamic simulation of the shell magazine was carried out. The simulation results indicate that the control algorithm has high control precision.

Emergency Evacuation Plan of the Louvre Based on Cellular Automata Superposition Model

The Louvre is a famous French building and a tourist attraction.It is of great significance to make an emergency evacuation plan for tourists.A social force model and cellular automata were established to simulate the crowd evacuation in unidimensional plane,and then the downstairs model was considered to simulate three-dimensional evacuation.Finally the real evacuation situation was simulated,considering the hazard source as well as other factors.The study found that the exit was closer to the corner,and the evacuation distance of descending stairs could be controlled between 0.3 and 0.6 m to maximize evacuation efficiency.The influence of the hazard at the edge of the channel was greater than that at the center of the channel.Therefore,in the process of evacuation,the staff should be guided to the nearest exit,to maintain the optimal distance,the staff to eliminate the danger source in the center of the passage.

Design and test of the anti-skid system for self-propelled high-stem crop sprayers

Aiming at the problem of skidding in the operation of a self-propelled high-stem crop sprayer due to uneven road surface and uneven distribution of soil cohesive force,This study proposed a four-wheel drive hydraulic anti-skid control system based on RTM valve.Through theoretical analysis of control components such as the RTM valve and steering cylinder,the control model of the anti-skid drive system of the spray machine is established,and the simulation test is carried out in Matlab/Simulink.The simulation results show that the slip rate of the anti-skid drive system based on the PID control strategy is controlled below 0.05,and the RTM valve keeps the driving pressure of the system basically stable.In order to verify the reliability of the simulation results,the designed drive anti-skid control system was carried out on a spray machine for the field test.The experimental results show that the slip rate of the drive anti-skid system decreases from 86.7%to 1.25%when the anti-skid function is turned on,indicating that the designed drive anti-skid system has good anti-skid performance.