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This paper presents a trajectory controller for a Hovering type Autonomous Underwater (HAUV) Vehicle to meet the demands of in-water ship hull inspection. Accomplishing this task can just be done by a vehicle that has all special requirements like high maneuverability, precise controllability and especially Hovering Capability, utility of such vehicle causes increasing precision, saving more time and money and less health hazard of divers. Thrusters' configuration in terms of number of the thrusters, position and the thrust direction of each thruster is presented to provide the most suitable formation in terms of less energy consuming, reducing complexity of control strategies and control the most degrees of freedom. In this paper, roll degree of freedom is just constrained. The controller is demonstrated, was designed upon the linearized dynamic model and then applied to the non-linear model to validate the controller's practicality. This controller consist of 3 different loops, one for horizontal plane another for the vertical plane, both where designed in state space and the last one is a PID controller which is developed to control the forward speed. In the next step, the robustness of the controller is investigated in the presence of underwater disturbance and uncertainty of the hydrodynamic coefficients. State feedback controllers have the advantages such as being suitable for non-linear models, useful for MIMO system and simplicity in application development.

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One of the most common problems that occur during machining is Machine tool chatter, which adversely affects surface finish, dimensional accuracy, tool life and machine life. Machine tool chatter can be modeled as a linear time invariant differential equation with time delay or delay differential equation. Infinite dimensional nature of delay differential equations is apparent in the study of time delay systems. The analytical stability methods are thus more difficult for these differential equations and approximate methods do not give accurate results. In this paper, a new method is developed to determine the exact stable region(s) in the parameter space of machine tool chatter. In this method, first, the bifurcation points are determined. Then, the Lambert function is used to decide on the stability characteristics of each particular region. The advantages of this method are simple implementation and applicability to high order linear time delay systems. By resulting stability regions from this method, we can choose an optimal spindle speed to suppress the chatter. The new approach is the most acceptable method with comparison to traditional graphical, computational and approximate methods due to excellent accuracy and other advantages.

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Alzheimer is the most common form of dementia. Amyloid beta peptides play a key role in the pathology of Alzheimer and the recent surveys have demonstrated that amyloid beta oligomers are the most toxic component of them. Among oligomers, considering the high durability of dimer in comparison to other kinds, it has more toxic effects. Prefoldin is a molecular chaperone which prevents accumulation of misfolded proteins. Prefoldin is demonstrated that it can also operate as a nano actuator. In this article, we investigate the interaction between the prefoldin nano actuator and dimeric pathogenic nano cargo in molecular dimensions, hence the all-atom molecular dynamic simulation in explicit solvent were performed at physiological temperature. Visualizing the results and investigating the atomic distance between nano actuator and pathogenic nano cargo revealed that two arms of six arms of prefoldin nano actuator have been able to capture cargo and during the simulation they have made hydrogen bonds. Furthermore, investigating the hydrophobic effects between the hydrophobic amino acids in the cargo and nano actuator revealed that these effects have positively affected the stability of the binding between arms and the cargo. This article introduces the prefoldin as an inhibitor factor for dimeric oligomer from amyloid beta.

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Currently, hovering type autonomous underwater vehicles (HAUV’s) are very noteworthy, due to theirs unique capabilities and features. Appropriate maneuverability and controllability is the most important feature for a HAUV that, make it better than other AUV’s. In order to increase stability and controllability of robot, the ballast tank is applied for a HAUV. Using of ballast tank in HAUV was not common before. In this paper a new underwater vehicle is presented, including three ballast tanks and three thrusters. In this underwater vehicle, the number of thrusters is less than original robot. In this paper, dynamics modeling and tracking control of this new underwater vehicle is investigated. The results show that the heave and pitch DOF’s can be reachable by using of the ballast tanks and we don’t need to use extra thrusters for these degrees of freedoms.

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In this study, we tried to have investigation of elastic properties of Prefoldin nano-actuator on the microscopic scale. Prefoldin is a molecular chaperone that prevented the aggregation of misfolded proteins and it has been shown that it can also serve as a Nano-actuator (drug delivery). To this end, steered molecular dynamics simulations have been used, which investigate the theory of spring constant in the molecular test based on the theory of two springs in series. The results expressed in form of young’s modulus. The results show that Prefoldin nano actuator exhibit different behaviors at different pulling rates and to what extent of tension, each tentacle of this nano actuator remains stable. The resulting Young's modulus for the Prefoldin chains was obtained at a rate of (3-3.3 ± 0.01 Gpa). By providing the complete understanding of mechanical properties of Prefoldin nano actuator, it is possible to exact investigating of Prefoldin nano actuator applications in intelligent drug delivery and capture the pathogenic cargos.