Rotary steering systems(RSSs)have been increasingly used to develop horizontal wells.A static push-the-bit RSS uses three hydraulic modules with varying degrees of expansion and contraction to achieve changes in the p...Rotary steering systems(RSSs)have been increasingly used to develop horizontal wells.A static push-the-bit RSS uses three hydraulic modules with varying degrees of expansion and contraction to achieve changes in the pushing force acting on the wellbore in different sizes and directions within a circular range,ultimately allowing the wellbore trajectory to be drilled in a predetermined direction.By analyzing its mathematical principles and the actual characteristics of the instrument,a vector force closed-loop control method,including steering and holding modes,was designed.The adjustment criteria for the three hydraulic modules are determined to achieve rapid adjustment of the vector force.The theoretical feasibility of the developed method was verified by comparing its results with the on-site application data of an imported rotary guidance system.展开更多
Static aerobic composting of municipal sewage sludge with forced ventilation or air ventilation using matured compost as bulking conditioner was investigated. Physical and chemical parame ,eters, e.g., temperature, mo...Static aerobic composting of municipal sewage sludge with forced ventilation or air ventilation using matured compost as bulking conditioner was investigated. Physical and chemical parame ,eters, e.g., temperature, moisture content, VSS, CODcr, pH, and germination index （GI）, were analyzed to characterize the composting process. Fermentation starts quickly in both forced and air ventilation compost heaps and reaches high-temperature stage after 2 d, owing to the bulking function of matured compost. Compared to air ventilation, however, forced ventilation enables the high-temperature stage to last longer for approximately 7 d. The moisture content of both compost bodies decreases from 62% to about 50% as a result of evaporation, and it decreases slightly faster in forced ventilation compost heap after 13 d due to the higher temperature and better ventilation condition. Although no obvious differences of VSS and pH are observed between both compost heaps, the soluble CODcr and GI show differences during the second half period of fermentation. In forced ventilation compost, the soluble CODcr has a small rebound after 13 d, and GI decreases from 46% to 35% but then increases. These results show that in general, the matured compost is a good conditioner and force ventilation with a proper air supply strategy can be more efficient than air ventilation.展开更多
The development of a theoretical model to predict the four equilibrium forces of reaction on a simple ladder of non-adjustable length leaning against a wall has long remained an unresolved matter. The difficulty is th...The development of a theoretical model to predict the four equilibrium forces of reaction on a simple ladder of non-adjustable length leaning against a wall has long remained an unresolved matter. The difficulty is that the problem is statically indeterminate and therefore requires complementary information to obtain a unique solution. This paper reports 1) a comprehensive theoretical analysis of the three fundamental models based on treating the ladder as a single Euler-Bernoulli beam, and 2) a detailed experimental investigation of the forces of reaction as a function of applied load and location of load. In contrast to previous untested proposals that the solution to the ladder problem lay in the axial constraint on compression or the transverse constraint on flexure, the experimental outcome of the present work showed unambiguously that 1) the ladder could be modeled the best by a pinned support at the base (on the ground) and a roller support at the top (at the wall), and 2) the only complementary relation needed to resolve the static indeterminacy is the force of friction at the wall. Measurements were also made on the impact loading of a ladder by rapid ascent and descent of a climber. The results obtained were consistent with a simple dynamical model of the ladder as a linear elastic medium subject to a pulse perturbation. The solution to the ladder problem herein presented provides a basis for theoretical extension to other types of ladders. Of particular importance, given that accidents involving ladders in the workplace comprise a significant fraction of all industrial accidents, the theoretical relations reported here can help determine whether a collapsed structure, against which a ladder was applied, met regulatory safety limits or not.展开更多
For statically indeterminate structure, the internal force will be changed with the translation of the supports, because the internal force is related to the absolute value of the stiffness EI. When the tension is dif...For statically indeterminate structure, the internal force will be changed with the translation of the supports, because the internal force is related to the absolute value of the stiffness EI. When the tension is different with the compression modulus, EI is the function of internal force and is not constant any more that is different from classic mechanics. In the other words, it is a nonlinear problem to calculate the internal force. The expression for neutral axis of the statically indeterminate structure was derived in the paper. The iterative program for nonlinear internal force was compiled. One case study was presented to illustrate the difference between the results using the different modulus theory and the single modulus theory as in classical mechanics. Finally, some reasonable suggestions were made for the different modulus structures.展开更多
An eight-channel force loading system is presented, which adopts position control system and force control system switching model, small flow servo valve controlled capacious cylinder system scheme, intelligent PID al...An eight-channel force loading system is presented, which adopts position control system and force control system switching model, small flow servo valve controlled capacious cylinder system scheme, intelligent PID algorithm and distributed load approach. Through the analyses of the equivalent model of valve controlled cylinder force subsystem, a controller based on intelligent PID algorithm is designed, which is not sensitive to the variation of parameters such as environmental stiffness. According to the coupling of multiple load channels, a distributed load approach is employed in the superior monitor computer. Experimental results show that the system designed has high precision and robustness.展开更多
With the aid of different types of mechanoreceptors,human is capable of perceiving stimuli from surrounding environments and manipulating various objects dexterously.In this paper,a bio-inspired tactile fingertip is d...With the aid of different types of mechanoreceptors,human is capable of perceiving stimuli from surrounding environments and manipulating various objects dexterously.In this paper,a bio-inspired tactile fingertip is designed mimicking human fingertip in both structures and functionalities.Two pairs of strain gages and(Polyvinylidene Fluoride)PVDF films are perpendicularly arranged to simulate the Fast-Adapting(FA)and Slowly Adapting(SA)type mechanoreceptors in human hands,while silicones,Polymethyl Methacrylate(PMMA),and electronic wires are applied to mimic the skin,bone and nerve fibers.Both static and dynamic forces can be perceived sensitively.A preprocessing electric circuit is further designed to transform the resistor changes into voltages,and then filter and amplify the four-channel signals.In addition to strong robustness due to the embedded structure,the developed fingertip is found sensitive to deformations via a force test experiment.Finally,two robotic experiments explore its recognition ability of contact status and object surface.Excellent performance is found with high accuracy of 99.72%achieved in discriminating six surfaces that are ubiquitous in daily life,which demonstrates the effectiveness of our designed tactile sensor.展开更多
To balance the contradiction between higher flexibility and heavier load bearing capacity,we present a novel deformable manipulator which is composed of active rigid joints and deformable links.The deformable link is ...To balance the contradiction between higher flexibility and heavier load bearing capacity,we present a novel deformable manipulator which is composed of active rigid joints and deformable links.The deformable link is composed of passive spherical joints with preload forces between socket-ball surfaces.To estimate the load bearing capacity of a deformable link,we present a static force-based model of spherical joint with preload force and analyze the static force propagation in the deformable link.This yields an important result that the load bearing capacity of a spherical joint only depends on its radius,preload force,and static friction coefficient.We further develop a parameter estimation method to estimate the product of preload force and static friction coefficient.The experimental results validate our model.80.4%of percentage errors on the maximum payload mass prediction are below 15%.展开更多
A geometrical theorem for the static equilibrium of a common-point-force system has been proven by means of virtual-work principle: The equilibrium point of a common-point force system has a minimal weighted distance ...A geometrical theorem for the static equilibrium of a common-point-force system has been proven by means of virtual-work principle: The equilibrium point of a common-point force system has a minimal weighted distance summation to every fixed point arbitrarily given on each force line with a weighing factor proportional to corresponding force value. Especially the mechanical simulating technique for its inverse problem has been realized by means of pulley block. The conclusions for the inverse problem derived from mechanic method are in accordance with that given by the pure mathematical method, and the self-consistence of the theorem and its inverse problem has been demonstrated. Some application examples in engineering, economy and mathematics have been discussed, especially the possible application in the research of molecular structure, has also been predicted.展开更多
For a pipejacking, the jacking force is critical to balance the resistance force and to move the pipe string forwards. The driving mechanism of a curved pipejacking is more complicated than a straight-line pipejacking...For a pipejacking, the jacking force is critical to balance the resistance force and to move the pipe string forwards. The driving mechanism of a curved pipejacking is more complicated than a straight-line pipejacking, and its jacking force is also more difficult to be determined. The paper theoretically studies the jacking force of a curved pipejacking by considering the static equilibrium of earth pressure, resistance at cutting face, friction at pipe surface, and the driving force behind the pipe string. The derived theoretical formula can be used to estimate the driving forces of a straight-line or a curved pipejacking. Case study was performed by applying the theoretical and empirical formulae. After calibration, the corrected formula is more accurate and more applicable.展开更多
The calculation of force for a roll system has significant effects on cold roiled thin strip gauge adjustment of a 20-high Sendzimir mill. According to the rolling parameters and rolling plans of a ZR 22B-42 Sendzimir...The calculation of force for a roll system has significant effects on cold roiled thin strip gauge adjustment of a 20-high Sendzimir mill. According to the rolling parameters and rolling plans of a ZR 22B-42 Sendzimir mill in a silicon steel factory, the contact force and the resultant force of each roll in the roll system were calculated both in the static state and in the rolling state through C＋＋ programs. It was found that the contact force between the see ond intermediate driven roll and the back up rolls B and C was much lower than that between the other rolls in static state. The results also demonstrated that the resultant force are 59.5%-62%, 37.7%-40.3%, 87.1%-88.7% and 53.9%-56.7% of the rolling force at the second intermediate driven roll, the second intermediate idler roll, the back-up rolls B and C and the back-up rolls A and D, respectively. It was also revealed that the minimum contact force generated between the first intermediate roll and the second intermediate idler roll is 206.7 kN on the first roll ing pass, and that on the second rolling pass, the minimum contact force generated between the second intermediate driven roll and the back-up roll C is 470.7 kN.展开更多
Mooring model experiment and mooring line tension determination are of significance to the design of mooring systems and berthing structures. This paper mainly involves: (a) description and analysis of a mooring model...Mooring model experiment and mooring line tension determination are of significance to the design of mooring systems and berthing structures. This paper mainly involves: (a) description and analysis of a mooring model experiment; (b) derivation of static equilibrium equations for a moored ship subjected to wind, current and waves; (c) solution of mooring equations with the Monte Carlo method; (d) qualitative analysis of effects of pier piles on mooring line forces. Special emphasis is placed on the derivation of static equilibrium equations, solution method and the mooring model experiment.展开更多
A novel orthogonal-parallel six-axis force/torque sensor is studied based on a modified Stewart platform architecture,and the optimal design and experiment research of the sensor are discussed.Firstly,the model of ort...A novel orthogonal-parallel six-axis force/torque sensor is studied based on a modified Stewart platform architecture,and the optimal design and experiment research of the sensor are discussed.Firstly,the model of orthogonal parallel six-axis force/torque sensor based on improved Stewart platform architecture and its static mathematical model are proposed.Secondly,according to the actual working condition of the sensor,the sensor is optimized and the optimal solution is obtained.Then,the experimental prototype and calibration system is developed.Finally,the superiority of the sensor structure and the effectiveness of the optimization method are verified by calibration experiments.The results of the proposed method are useful for the further research and application of the orthogonal-parallel six-axis force/torque sensor.展开更多
基金supported by the Opening Foundation of China National Logging Corporation(CNLC20229C06)the China Petroleum Technical Service Corporation's science project'Development and application of 475 rotary steering system'(2024T-001001)。
文摘Rotary steering systems(RSSs)have been increasingly used to develop horizontal wells.A static push-the-bit RSS uses three hydraulic modules with varying degrees of expansion and contraction to achieve changes in the pushing force acting on the wellbore in different sizes and directions within a circular range,ultimately allowing the wellbore trajectory to be drilled in a predetermined direction.By analyzing its mathematical principles and the actual characteristics of the instrument,a vector force closed-loop control method,including steering and holding modes,was designed.The adjustment criteria for the three hydraulic modules are determined to achieve rapid adjustment of the vector force.The theoretical feasibility of the developed method was verified by comparing its results with the on-site application data of an imported rotary guidance system.
基金Projects(50978087,50908081)supported by the National Natural Science Foundation of China
文摘Static aerobic composting of municipal sewage sludge with forced ventilation or air ventilation using matured compost as bulking conditioner was investigated. Physical and chemical parame ,eters, e.g., temperature, moisture content, VSS, CODcr, pH, and germination index （GI）, were analyzed to characterize the composting process. Fermentation starts quickly in both forced and air ventilation compost heaps and reaches high-temperature stage after 2 d, owing to the bulking function of matured compost. Compared to air ventilation, however, forced ventilation enables the high-temperature stage to last longer for approximately 7 d. The moisture content of both compost bodies decreases from 62% to about 50% as a result of evaporation, and it decreases slightly faster in forced ventilation compost heap after 13 d due to the higher temperature and better ventilation condition. Although no obvious differences of VSS and pH are observed between both compost heaps, the soluble CODcr and GI show differences during the second half period of fermentation. In forced ventilation compost, the soluble CODcr has a small rebound after 13 d, and GI decreases from 46% to 35% but then increases. These results show that in general, the matured compost is a good conditioner and force ventilation with a proper air supply strategy can be more efficient than air ventilation.
文摘The development of a theoretical model to predict the four equilibrium forces of reaction on a simple ladder of non-adjustable length leaning against a wall has long remained an unresolved matter. The difficulty is that the problem is statically indeterminate and therefore requires complementary information to obtain a unique solution. This paper reports 1) a comprehensive theoretical analysis of the three fundamental models based on treating the ladder as a single Euler-Bernoulli beam, and 2) a detailed experimental investigation of the forces of reaction as a function of applied load and location of load. In contrast to previous untested proposals that the solution to the ladder problem lay in the axial constraint on compression or the transverse constraint on flexure, the experimental outcome of the present work showed unambiguously that 1) the ladder could be modeled the best by a pinned support at the base (on the ground) and a roller support at the top (at the wall), and 2) the only complementary relation needed to resolve the static indeterminacy is the force of friction at the wall. Measurements were also made on the impact loading of a ladder by rapid ascent and descent of a climber. The results obtained were consistent with a simple dynamical model of the ladder as a linear elastic medium subject to a pulse perturbation. The solution to the ladder problem herein presented provides a basis for theoretical extension to other types of ladders. Of particular importance, given that accidents involving ladders in the workplace comprise a significant fraction of all industrial accidents, the theoretical relations reported here can help determine whether a collapsed structure, against which a ladder was applied, met regulatory safety limits or not.
文摘For statically indeterminate structure, the internal force will be changed with the translation of the supports, because the internal force is related to the absolute value of the stiffness EI. When the tension is different with the compression modulus, EI is the function of internal force and is not constant any more that is different from classic mechanics. In the other words, it is a nonlinear problem to calculate the internal force. The expression for neutral axis of the statically indeterminate structure was derived in the paper. The iterative program for nonlinear internal force was compiled. One case study was presented to illustrate the difference between the results using the different modulus theory and the single modulus theory as in classical mechanics. Finally, some reasonable suggestions were made for the different modulus structures.
文摘An eight-channel force loading system is presented, which adopts position control system and force control system switching model, small flow servo valve controlled capacious cylinder system scheme, intelligent PID algorithm and distributed load approach. Through the analyses of the equivalent model of valve controlled cylinder force subsystem, a controller based on intelligent PID algorithm is designed, which is not sensitive to the variation of parameters such as environmental stiffness. According to the coupling of multiple load channels, a distributed load approach is employed in the superior monitor computer. Experimental results show that the system designed has high precision and robustness.
基金funded by National Natural Science Foundation of China under Grant No.52205009Natural Science Foundation of Jiangsu Province under Grant No.BK20210233Open Foundation of the State Key Laboratory of Fluid Power and Mechatronic Systems.
文摘With the aid of different types of mechanoreceptors,human is capable of perceiving stimuli from surrounding environments and manipulating various objects dexterously.In this paper,a bio-inspired tactile fingertip is designed mimicking human fingertip in both structures and functionalities.Two pairs of strain gages and(Polyvinylidene Fluoride)PVDF films are perpendicularly arranged to simulate the Fast-Adapting(FA)and Slowly Adapting(SA)type mechanoreceptors in human hands,while silicones,Polymethyl Methacrylate(PMMA),and electronic wires are applied to mimic the skin,bone and nerve fibers.Both static and dynamic forces can be perceived sensitively.A preprocessing electric circuit is further designed to transform the resistor changes into voltages,and then filter and amplify the four-channel signals.In addition to strong robustness due to the embedded structure,the developed fingertip is found sensitive to deformations via a force test experiment.Finally,two robotic experiments explore its recognition ability of contact status and object surface.Excellent performance is found with high accuracy of 99.72%achieved in discriminating six surfaces that are ubiquitous in daily life,which demonstrates the effectiveness of our designed tactile sensor.
基金supported by National Natural Science Foundation of China(NSFC)(61573198,61375087)the Natural Science Foundation of Tianjin(15JCZDJC31200)。
文摘To balance the contradiction between higher flexibility and heavier load bearing capacity,we present a novel deformable manipulator which is composed of active rigid joints and deformable links.The deformable link is composed of passive spherical joints with preload forces between socket-ball surfaces.To estimate the load bearing capacity of a deformable link,we present a static force-based model of spherical joint with preload force and analyze the static force propagation in the deformable link.This yields an important result that the load bearing capacity of a spherical joint only depends on its radius,preload force,and static friction coefficient.We further develop a parameter estimation method to estimate the product of preload force and static friction coefficient.The experimental results validate our model.80.4%of percentage errors on the maximum payload mass prediction are below 15%.
文摘A geometrical theorem for the static equilibrium of a common-point-force system has been proven by means of virtual-work principle: The equilibrium point of a common-point force system has a minimal weighted distance summation to every fixed point arbitrarily given on each force line with a weighing factor proportional to corresponding force value. Especially the mechanical simulating technique for its inverse problem has been realized by means of pulley block. The conclusions for the inverse problem derived from mechanic method are in accordance with that given by the pure mathematical method, and the self-consistence of the theorem and its inverse problem has been demonstrated. Some application examples in engineering, economy and mathematics have been discussed, especially the possible application in the research of molecular structure, has also been predicted.
文摘For a pipejacking, the jacking force is critical to balance the resistance force and to move the pipe string forwards. The driving mechanism of a curved pipejacking is more complicated than a straight-line pipejacking, and its jacking force is also more difficult to be determined. The paper theoretically studies the jacking force of a curved pipejacking by considering the static equilibrium of earth pressure, resistance at cutting face, friction at pipe surface, and the driving force behind the pipe string. The derived theoretical formula can be used to estimate the driving forces of a straight-line or a curved pipejacking. Case study was performed by applying the theoretical and empirical formulae. After calibration, the corrected formula is more accurate and more applicable.
基金Sponsored by Open Fund of Key Laboratory for Metallurgical Equipment and Control of Education Ministry of China(2013B03)
文摘The calculation of force for a roll system has significant effects on cold roiled thin strip gauge adjustment of a 20-high Sendzimir mill. According to the rolling parameters and rolling plans of a ZR 22B-42 Sendzimir mill in a silicon steel factory, the contact force and the resultant force of each roll in the roll system were calculated both in the static state and in the rolling state through C＋＋ programs. It was found that the contact force between the see ond intermediate driven roll and the back up rolls B and C was much lower than that between the other rolls in static state. The results also demonstrated that the resultant force are 59.5%-62%, 37.7%-40.3%, 87.1%-88.7% and 53.9%-56.7% of the rolling force at the second intermediate driven roll, the second intermediate idler roll, the back-up rolls B and C and the back-up rolls A and D, respectively. It was also revealed that the minimum contact force generated between the first intermediate roll and the second intermediate idler roll is 206.7 kN on the first roll ing pass, and that on the second rolling pass, the minimum contact force generated between the second intermediate driven roll and the back-up roll C is 470.7 kN.
文摘Mooring model experiment and mooring line tension determination are of significance to the design of mooring systems and berthing structures. This paper mainly involves: (a) description and analysis of a mooring model experiment; (b) derivation of static equilibrium equations for a moored ship subjected to wind, current and waves; (c) solution of mooring equations with the Monte Carlo method; (d) qualitative analysis of effects of pier piles on mooring line forces. Special emphasis is placed on the derivation of static equilibrium equations, solution method and the mooring model experiment.
基金Supported by the National Natural Science Foundation of China(No.51505124)Foster Fund Projects of North China University of Science and Technology(No.JP201505)the Science and Technology Research Project of Hebei Province(No.ZD2020151).
文摘A novel orthogonal-parallel six-axis force/torque sensor is studied based on a modified Stewart platform architecture,and the optimal design and experiment research of the sensor are discussed.Firstly,the model of orthogonal parallel six-axis force/torque sensor based on improved Stewart platform architecture and its static mathematical model are proposed.Secondly,according to the actual working condition of the sensor,the sensor is optimized and the optimal solution is obtained.Then,the experimental prototype and calibration system is developed.Finally,the superiority of the sensor structure and the effectiveness of the optimization method are verified by calibration experiments.The results of the proposed method are useful for the further research and application of the orthogonal-parallel six-axis force/torque sensor.
