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A novel wideband circularly polarized reconfigurable antenna for 5G devices is presented in this paper. Left hand and right-hand circular polarizations were achieved using the sequential phase rotation feeding network based on 90° hybrid coupler. The proposed antenna has a bandwidth (with AR ≤ 3 dB) of 24.8% and 4% for right hand circular polarization (RHCP) and left-hand circular polarization (LHCP) mode, respectively. At 3.75 GHz, the degree of circular polarization is 42° in LHCP mode and 51° in RHCP mode showing the potential of this proposed antenna for modern 5G terminal devices.

In this work, we propose a smart shoe integrated with a very-low power wireless sensor node operating in Bluetooth Low Energy (BLE) 5.0 standard. The sensor node consists of a miniaturized printed inverted-F antenna, an accelerometer and a gyroscope being placed at the bottom of the shoe to measure footstep-length, running speed and foot landing angle. The maximum power consumption of the sensor is 11 mW and it is sustained by a triboeletric nanogenerator (TENG) which generates power from the friction causing by user's motion itself and an energy storage circuit. The triboelectric energy harvester, having the size of 6 cm × 6 cm, is made of multiple pairs of triboelectric materials can harvest up to 32 mW/m2, enough to supply the sensor node.

Vietnam is among the South-Asian regions the one that better supplies remote areas. However, many islands and remote areas are still not connected to the main grid and this fact jeopardizes their development, while forcing people to move to urban areas. With a high potential from renewable energy sources and a lot of islands, Vietnam has thus many favorable environmental features for developing the microgrids technology. In this chapter, a detailed analysis about opportunities and challenges for widespread deployment of microgrids technology in Vietnam is considered. Such analysis is based on the assessments of the potential from renewable energy sources in the country and of the national policy framework for the development of renewable energy sources. In the application section, results from the test of improved optimized control strategies to one microgrid system are presented. The results show that such cutting-edge technologies can improve the applicability of the microgrid technology thus reducing its Return on Investment cost.

In robotics technology, tolerance design is a part of mechanical design and determines the final product quality. The spatial dimensional chain problem of the parallel structure with component links having an active assembly and the closed link having a given error is a complex one. Determining the relationship between the end effector tolerances and component link tolerances of each leg in general form is the basis for digitizing the problem. Calculating the initial approximation of tolerance for other structures in the group based on the sample solution has the meaning of deciding time and quality of calculation. This paper proposes a hypothesis that it is always possible to determine a reasonable initial approximation based on a sample solution. Therefore, the process of calculating tolerances of the component kinematic parameters of parallel industrial robots is significantly shortened.

This paper presents a simple and effective method to obtain joint inputs needed to attain any point in the reachable workspace of the class two-degree-of-freedom planar parallel manipulators, which are based on five rigid links and five single degree of freedom joints - revolute and prismatic joints. By using the close-loop vector theory, the kinematic equation is obtained and changed into a nonlinear optimization problem with constraints to the RosenBrock-Banana objective function form. The optimum solutions of the inverse and forward kinematic problem were implemented with a Generalized Reduced Gradient algorithm. The method has been applied to solve the kinematic problem to a representative mechanism in the class (5-bar planar parallel robot). Experimental results with achieved position accuracy of 0.012 mm as well as numerical simulation results have demonstrated the method advantage, including high accuracy results, fast calculation time, simple implementation and the feasibility when applied to the class of two-degree-of-freedom parallel mechanism in practice.

Robot-type structures have many different methods to calculate tolerances, the results of these methods are not the same and therefore the manufacturing costs and processing technology are not identical. This paper presents two points of view to calculate different robot structure tolerances and then show reasonable methods to apply in practice. The basis of calculating tolerances from the view of structural kinetic response and the view of manufacturing technology is presented. Calculated results are documented on the same robot with the same required accuracy. Then the comparison of manufacturing costs will be made to identify the more suitable option. The results of this paper are suggestions for calculating similar structures effectively for those interested.

Whether new or used, industrial robots still have kinetic errors for many reasons such as quality of manufacture, assembly, wear, elastic deformation … and these errors are also changed by time. Feedback control only aims to make the generalized variable close to the theoretical calculation from the kinetic model so it is impossible to solve many of the above reasons, for example errors due to elastic deformation or wear owing to the out-of control loop. It is necessary to calibrate the robot by measuring the end manipulator error. Robots are mechatronic products so it is feasible to interfere with software to adjust hardware. This paper introduces an algorithm to build an alternate trajectory of the desired trajectory for the purpose of controlling the robot to follow this trajectory, which will move closest to the desired trajectory. This approach has the advantage of not interfering with the robot’s hardware and control system structure, it also allows the quality of initial robot manufacturing and assembly to be moderate to keep prices reasonable. When kinetic errors increase over time, we only need to rebuild the trajectory instead. The calculations illustrated here show that this is a promising process when applied because of its effectiveness.

Some continuous physical quantities usually exist in the form of fields (thermal, pressure, humidity, sound, light…). In the fields, they have consecutively changing values between neighbouring points. There exist points where the same parameter intensity forms a sub-field. Determining exactly the coordinate of the sub-field is presented in this article. Here, we present the parametric intensity modeling problem in the field in a general form based on the shape function technique. Surveying this model with the Generalized Reduced Gradient method will allow determining of the points having the required parameter values. The illustrative calculations of thermal in this paper show that the solutions of both the forward and reverse problems are very fast. This technique is very effective when applied to the drying process in the paint, arranging pottery in the furnace.

Aspect-based sentiment analysis is an emerging trend in the NLP area nowadays. One of the major tasks in this work is to identify corresponding aspects for rating sentiment. Ontology is considered highly useful to cope with this issue, due to its capability of capturing and representing concepts in a certain domain. However, ontology-based sentiment analysis suffers from the difficulty when handling anaphoric coreference of mentioned entities, which commonly occurs in textual documents. This paper addresses this problem by introducing an approach combining coreference resolution with ontology inference. The initial results are quite promising.