This paper discusses the stability of an equilibrium point of an ordinary differential equation (ODE) arising from a feed-forward position control for a musculoskeletal system. The studied system has a link, a joint a...
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On the basis of the hydromagnetic flow theory, an inertia hydromagnetic lubrication equation has been derived for circular stepped squeeze film disks by applying the momentum integral method. Analytical solution of th...
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Existing works on control of tractor-trailers systems only consider the kinematics model without taking dynamics into account. Also, most of them treat the issue as a pure control theory problem whose solutions are di...
Existing works on control of tractor-trailers systems only consider the kinematics model without taking dynamics into account. Also, most of them treat the issue as a pure control theory problem whose solutions are difficult to implement. This paper presents a trajectory tracking control approach for a full-scale industrial tractor-trailers vehicle composed of a carlike tractor and arbitrary number of passive full trailers. To deal with dynamic effects of trailing units, a force sensor is innovatively installed at the connection between the tractor and the first trailer to measure the forces acting on the tractor. The tractor's dynamic model that explicitly accounts for the measured forces is derived. A tracking controller that compensates the pulling/pushing forces in real time and simultaneously drives the system onto desired trajectories is proposed. The propulsion map between throttle opening and the propulsion force is proposed to be modeled with a fifth-order polynomial. The parameters are estimated by fitting experimental data, in order to provide accurate driving force. Stability of the control algorithm is rigorously proved by Lyapunov methods. Experiments of full-size vehicles are conducted to validate the performance of the control approach.
Inspired by widely used soft fingers on grasping, we propose a method of rigid-soft interactive learning, aiming at reducing the time of data collection. In this paper, we classify the interaction categories into Rigi...
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Modeling system dynamics becomes challenging when the properties of individual system components cannot be directly measured, and often requires identification of properties from observed motion. In this paper, we sho...
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Modeling system dynamics becomes challenging when the properties of individual system components cannot be directly measured, and often requires identification of properties from observed motion. In this paper, we show that systems whose movement is highly dissipative have features which provide an opportunity to more easily identify models and more quickly optimize motions than would be possible with general techniques. Geometric mechanics provides means for reduction of the dynamics by environmental homogeneity, while the dissipative nature minimizes the role of second order (inertial) features in the dynamics. Here we extend the tools of geometric system identification to "Shape-Underactuated Dissipative Systems (SUDS)" – systems whose motions are more dissipative than inertial, but whose actuation is restricted to a subset of the body shape coordinates. Many animal motions are SUDS, including micro-swimmers such as nematodes and flagellated bacteria, and granular locomotors such as snakes and lizards. Many soft robots are also SUDS, particularly robots that incorporate highly damped series elastic actuators to reduce the rigidity of their interactions with their environments during locomotion and manipulation. We motivate the use of SUDS models, and validate their ability to predict motion of a variety of simulated viscous swimming platforms. For a large class of SUDS, we show how the shape velocity actuation inputs can be directly converted into torque inputs, suggesting that systems with soft pneumatic or dielectric elastomer actuators can be modeled with the tools presented. Based on fundamental assumptions in the physics, we show how our model complexity scales linearly with the number of passive shape coordinates. This scaling offers a large reduction on the number of trials needed to identify the system model from experimental data, and may reduce overfitting. The sample efficiency of our method suggests its use in modeling, control, and optimization in ro
This research is focused on the effects of impregnation ratios using KOH/KMnO4 as multiple function activation agents on microporous of activated carbon. Rubberwood sawdust, the waste from wood processing industry, wa...
This research is focused on the effects of impregnation ratios using KOH/KMnO4 as multiple function activation agents on microporous of activated carbon. Rubberwood sawdust, the waste from wood processing industry, was used as a raw material in synthesis of activated carbon by chemical activation. The rubberwood sawdust was carbonized at 400 °C for 1 hour under an inert atmosphere to produce char. Chars were impregnated with different proportions of KOH and KMnO4. Impregnation time for each mixture proportion (Char: KOH: KMnO4) was 24 hours before activation for 3 hours at 800 °C. The surface area, pore volume, micropore volume, pore size distribution, porous structure, and adsorption isotherm were examined and considered as the properties of activated carbon. The results showed that the activated carbon with an impregnation ratio of 10:10:5, 10:30:0, and 10:30:5 have the surface area 750.89 m 2/g, 1574.39 m 2/g, and 1346.10 m 2/g, respectively. The pore volume and micropore volume were in the range between 0.3289-0.6405 cm 3/g and 0.1920-0.3533 cm 3/g. The average pore sizes were 1.75 nm, 1.63 nm, and 1.65 nm, respectively. These synthesized activated carbons were characterized as type I isotherm and microporous solids.
In the presence of hydrodynamic motion interference between pusher and multiple barge configurations, a reliable investigation allowing an accurate prediction of her total resistance is obviously required. To achieve ...
In the presence of hydrodynamic motion interference between pusher and multiple barge configurations, a reliable investigation allowing an accurate prediction of her total resistance is obviously required. To achieve such objective, the Computational Fluid Dynamics (CFD) approach is then proposed to predict the total ship’s resistance of a pusher-barge system in the calm water condition. The various barge’s configurations incorporated with various Froude numbers (Fr) have been considered in the computational simulation incorporated with the full-scale dimension of the pusher-barge. In general, the CFO results revealed that the total resistances of the various configurations of the pusher-barge system had a qualitatively good agreement with the experimental model test results. Merely, the increase of Froude number (Fr=0.128 to 0.308) was proportional to the magnitude of total resistance. In addition, the pusher-barge system of the 33BP configuration provides the highest resistance as compared to others. It should be noted here that the pusher-barges configurations led to the susceptible effect to the total ship’s resistance which resulted in remarkable increase of the effective power values as the substituting their arrangements from the longitudinal configurations and to the lateral ones. This finding provides a very valuable insight aimed at selecting the proper pusher-barge configurations towards reducing the total ship’s resistance.
The supercapacitor is significant in daily life. It is an alternative option that can storage energy. This research focused on studying the effect of Potassium hydroxide concentration content increasing surface area o...
The supercapacitor is significant in daily life. It is an alternative option that can storage energy. This research focused on studying the effect of Potassium hydroxide concentration content increasing surface area of the Borassus flabellifer shell charcoal (BFC), power density and energy density of activated carbon as electrode and cycles. Borassus flabellifer shell as agricultural waste was carbonized with tube furnace at nitrogen atmosphere by heated at 400 °C for 1 hour. Activated carbon with KOH (the mass ratio of KOH: BFC; 1:1, 1:2, 1:3, 4:1 and 5:1) (BAC) was heated at 900 °C for 2 hours. The results of the research show that suitable concentration of KOH: BFC to activated with higher pore volume and higher surface area. BAC- 5 (5:1) is the highest pore volume of 1679.61 m 2/g and the highest pore volume of 0.737 (cm 3/g) but BAC-4 (4:1) is the best because it has a similar surface area and is economical, the highest pore volume of 1607.092 m 2/g and the highest pore volume of 0.686 (cm 3/g). BAC-1, BAC-2, BAC-3, BAC-4 and BAC-5 have average pore diameters, respectively, around of 1.609 nm., 1.641 nm., 1.742 nm., 1.708 nm. and 1.754 nm. The average pore size of products is microporous.
The very high strength of Reactive Powder Concrete (RPC) is possible to produce due to the availability of a pozzolanic material in the mixture and application of the packing density method to obtain the optimum densi...
The very high strength of Reactive Powder Concrete (RPC) is possible to produce due to the availability of a pozzolanic material in the mixture and application of the packing density method to obtain the optimum density of the mixture proportions. Rice husk ash is a natural source of high silica (SiO2) with readiness in huge volumes. In this study, the RPC mixtures were produced from a fixed content of 25% silica fume of the cement weight combined with synthesized rice husk ash (SRHA) of 10%, 20%, and 30% by cement weight. Mix proportions were obtained by using the Modified Andreassen Packing Model method. This study aims to determine the width of slump flow and compressive strength under normal and steam curing of RPC with low cement content (650 kg/m3). The results demonstrated that the intermix of silica fume with synthesized rice husk ash up to 30% provides an advance on the slump flow width and compressive strength of RPC containing local quartzite powder under normal and steam curing.
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