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Parallel piezo-flexural nanopositioning stages are extensively used in advanced nano-scale imaging and manipulation applications such as scanning probe microscopy systems. One of the major deficiencies of these devices is the coupled motion between their different axes. That is, the motion of stage in one direction interferes with motions in the other directions, leading to undesirable disturbances. In this paper, analytical, dynamic, experimental, and finite element analyses are carried out to investigate the major root cause of the cross-coupling effect. Using ABAQUS FEA software, a 3D model of the stage has been developed. Model consists of a central elastic body connected to the fixed frame through four flexural hinges. A cylindrical stack of multiple piezoelectric layers is placed between the moving central body and the fixed frame. Simulations are carried out for two different friction coefficients in the contact surfaces of the piezoelectric layers, and for different frame materials. It is observed that the main cause of the cross-coupling effect is the rotation of piezoelectric stack due to its friction with the stage moving in the tangential direction, concurrent with a change in the geometry of the stage.

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This paper presents a new approch in the design of output feedback control system based on disturbance observer for dynamic positioning vessels. The proposed control system includes a controller and a structure of a modified notch filter and a nonlinear observer. The filter is used for estimating low-frequency motions and removing the wave-frequency motions by using vessel position mesurement. The low-frequency disturbances and vessel-velocites are estimated in nonliner observer using the low-frequency vessel motion. In this structre, wave filtering and low-frequency motion estimation are independent from the estimation of low-frequency disturbances and vessel velocities. It causes to incease the accuracy of filtering and estimation which results in desirable performance of control system. Also, filtering is independent of the vessel and low frequency disturbances models, and therefore it is not affected by modeling uncertainty. The effect of wave filtering and low-frequency disturbances estimation in DP control system from the point of reducing control signal flactutions were evaluated with numerical simulation. This is important in view of reduction of wear and tear in propaltion system and fuel consumption in a surface vessel. Futhermore, simulation results show that the proposed method has better performances in comparision with conventional method.

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Piezoelectric actuators (PA) are widely used in electromechanical system thank to interesting properties such as: high resolution, fast response, wide bandwidth, mechanical simplicity, high stiffness. Despite these unique desirable properties, they suffer from nonlinear behaviors which adversely affect the positioning accuracy. Among them, hysteresis between applied voltage , actuator position is the most important nonlinearity which can lead to significant error if not compensated. In this study, a sliding mode controller associated with an unknown input observer, which uses the position feedback provided by a selfsensing circuit, is suggested to use in micro positioning applications. The selfsensing technique is based on the linear relation between position , charge, which is measured by an active charge measurement circuit. The advantages of proposed scheme could be summarized as follows. It is a sensorless method which does not need an external position sensor. It does not need any operators to model hysteresis or its inverse. It has improved performance in comparison to traditional controllers like proportional integral (PI) controller. Obtained experimental results demonstrate the effectiveness of proposed method to use in micro-positioning applications.

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In recent years the administrative organizations have witnessed increasing changes in the world of management, facing them with a range of principles and ideas suggesting them how to brace success in making their objectives come true. Recognition of the customers' needs and factors effective on their satisfaction, and adopting proper strategies to meet them; also to know where the organization is standing in the competition arena, are of the most important activities by the organizations. The Statistical Center of Iran, as the organization in charge of the national statistical system, ought to seek the customers' and users' satisfaction over the services provided by the SCI and to further cement its significant position. The present research seeks to figure out the position of the SCI in the eyes of its customers. To choose the criteria and prioritize them the Analytical Hierarchy Process model (AHP) was used and to find out the SCI's position the improved model by Cook & Siford, a multi attribute decision making model (MADM) was applied. For the study, in the first step the indexes effective on positioning the SCI including data accuracy, data accessibility, data trustworthiness, and data objectivity were picked up; and in the second, the significance of each index was estimated in two ways: (1) from the viewpoint of the SCI's senior experts, (2) in the eyes of data users. In order to determine the positions of a number of organizations in addition to the SCI, the Assignment model by Cook & Siford was used. The expected results of the study are to figure out the current position of the SCI in connection with 4 major and 20 minor indices and determining its general position as compared to those of peer organizations. At the end some suggestions are offered.

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The 2D position of a defect as well as its through-thickness length can be measured by ultrasonic time-of-flight diffraction technique (TOFD). By considering the methods used for detecting and positioning a target in radar, acoustic and sonar systems, an algorithm was developed for 3D positioning of defects in TOFD measurements. In this algorithm, the unknown parameter to be determined is the time difference of arrival (TDOA). While the developed algorithm is sufficiently fast, it suffers from various errors affecting the TDOA. The sensitivity of TDOA to errors is more noticeable when the distance between the receivers and the midplane (a plane with a minimum distance from the receivers) is small. This problem cannot be easily resolved when the receivers are coplanar. In this paper, using a closed form solution, a new algorithm is proposed for solving this problem. In this algorithm, by considering hypothetical locations for receivers, both the target (defect) and the positions of receivers are simultaneously verified. These hypothetical positions are obtained in such a way that their distances from the midplane is within acceptable limits. To validate the algorithm, it is used for determining the position of an artificial defect in a carbon steel block. The results prove that the algorithm is accurate and can be used in case of 3D TOFD measurements in which the receivers are usually coplanar.

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Increasing demand of tourists to visit natural attractions, historical sites, cultural and religion places provides a fertile ground for the development of tourism. Having unique capabilities, such as a plenty of natural and historical attractions, Iran is able to develop tourism. To gain more tourism, there is a need to identify the strengths and weaknesses of these capabilities. This study aimed to positioning of Iran's historical sites By important /performance analysis and perceptual Mapping approach from tourists' point of view. In terms of objective, this research is an applied research, and in terms of the data collection it can be classified as a descriptive survey. Statistical population is foreign tourists who have visited each of the three historical sites, i.e. Persepolis, Ali Qapu, and Jame Mosque of Isfahan. Based on literature overview, a questionnaire of 23 features related to historical sites is designed to evaluate the importance and satisfaction related to the site. Data analyzed using SPSS16 and the perceptual map drawn using MATLAB(R2009a). Using Exploratory Factor Analyses, features classifies in seven key factors. Utilizing Importance –Satisfaction Analysis, the perceptual map of the three sites was drawn. The results show that the position of these sites is almost alike. Both hygienic and information factors are main weaknesses of the three sites, while the attractiveness of the sites and accessibility factor are the strengths of the sites. Also, all the three sites have weaknesses in eating and resting, and music factors.

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In recent years, scientific advances in navigation systems and technological development of low-power consumption and high-precision in magnetic sensors have made researchers to realize that earth’s magnetic field can be applied for locating purposes. Earth’s magnetic field is applied in the navigation method where the required data from earth’s magnetic field can be read from high accuracy magnetic sensors. It is possible to determine the location by comparing the data with the reference maps through adaption of algorithms and/or filtering. Generally, in this method of locating, the inertia system is used to determine the velocity and condition, and the magnetic navigation system represents navigational assistance. In the first step toward obtaining a magnetic locating system, a reference magnetic map must be created; so, it is required to carefully analyze the earth’s magnetic field, the quantity, and quality of the field variations over different time and places. In this paper, the possibility of obtaining the geographical location of an observatory by extracting available data of a magnetic observatory has been investigated and, then, the effect of the displacement of geographical location on the magnitude of the earth's magnetic field has been examined by an experimental test. The results of simulation and data collection confirm the fact that geographic location for a variety of vehicles can be attainable just using earth's magnetic field data and there is no need to use any other navigation sensors.

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The main goal of this paper is to develop a special modular fixture system for machining and drilling parts that hold pneumatic jacks componets. This family of parts is usually made in various dimensions and sizes but with a specific geometric shape. The design requirements of the restrictions, the way of the construction process is considered as the design inputs of this system.
Positioning and clamping system have been designed, modeled and simulated for the mass production of a family of these parts with minimal changes in the manufacturing process. The results obtained from the idea of designing such restraints in machining processes show that with its help, it is possible to reduce the design and manufacturing costs of restraints for a group of parts that are similar in appearance but different in size and dimensions. It will significantly reduce and minimize the time of adjusting these equipments during the production process and will increase the productivity and circulation of products.

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This paper presents an innovative bulk magnetostrictive actuator made of a 2V-Permendur alloy rod, capable of functioning across multiple deformation modes—longitudinal, torsional, and flexural. In longitudinal mode, displacement is produced by the Joule effect, where a magnetic field applied along the rod’s axis, generated by a surrounding coaxial coil, induces deformation along its length. Torsional mode activation follows the Wiedemann effect, wherein an electric current passed directly through the rod produces a circumferential magnetic field that twists the material. Additionally, flexural deformation is achieved by a special designed magnetic core that directs a magnetic field to the rod’s surface, producing bending movements along the rod’s length. The actuator operates using controlled DC magnetic fields. Experimental results demonstrated outstanding performance, with maximum displacements reaching 12 microns in longitudinal mode, 7 microns in flexural mode, and 0.15 degrees in torsional mode. Such multi-functional performance highlights the actuator’s potential in precision positioning systems, with particular suitability for advanced microscopy, optical instrumentation, and other fields requiring sub-micrometer positioning accuracy.