Global Navigation Satellite Systems (GNSS) spoofing is a pernicious type of intentional interference where a GNSS receiver is fooled into tracking counterfeit signals, with the purpose of inducing a misleading information into the application it is used for. A possible technique able to identify a GNSS spoofing attack is a dual-antenna method based on the analysis of the dispersion of the double differences (D3) of carrier-phase measurements. Such technique has been recently presented as a relatively simple method to detect situations where even only a subset of counterfeit signals is tracked by the receiver. However, the D3 technique has not been analyzed in a rigorous theoretical way so far and the detection threshold was, for instance, set only empirically. Aiming at filling these gaps, this article intends to revise the main concepts of the aforementioned technique in a clear mathematical way. Thus, the detection threshold will be given according to a target probability of missed detection. Moreover, the article provides a thorough analysis of expected performance in terms of probability of missed detection and probability of false alarm, addressing them first as pairwise probability, then as overall probability. The effect of the signal C/N0 ratio on these detection performances is analyzed. Methods to reduce the occurrence of events of false alarm are also discussed. Eventually, an assessment of performance of the ${{\rm{D}}^3}$ algorithm is evaluated through a set of tests that emulate real working conditions.

This article introduces the reader to past, current, and future trends in science teacher preparation and professional development in Vietnam. The authors rely on document analysis for data collection and focused analysis to describe the general education system and the mechanisms for teacher training in Vietnam from the past to the present. Research questions focused on exploring changes in the organization of the education system over time, identifying advances that have been made, and describing what challenges teacher education faces today. In addition, this paper offers a special focus on how Vietnamese pedagogy institutions are working to prepare new teachers. Finally, the authors describe how Vietnam is preparing to implement a new national general education program that will strongly affect all aspects of education, including training and retraining of teachers. The authors conclude by raising some important questions for future research and development.

This paper presents an innovative powertrain design and an energy regeneration system for hybrid hydraulic excavators to reduce energy consumption and emissions. The proposed system is designed to maximize engine efficiency and make full use of the energy gained from boom and arm retraction. The powertrain features an innovative design that incorporates a continuously variable transmission (CVT), which drives the main pump. It enables precise control of both the engine’s speed and torque, ensuring that the engine operates within the high-efficiency range. The energy regeneration system is applied to regenerate the potential energy of the boom and arm, which can be used to either charge the battery or directly supply power to the main pump. Moreover, an energy management strategy based on an equivalent consumption minimization strategy is used to distribute the power while offering maximum engine efficiency. When compared with the existing hybrid system and conventional system, the simulation results indicated that the proposed approach achieves energy-saving efficiencies of $16.9\%$ and $77.1\%$, respectively, at high velocities and $22.25\%$ and $53.5\%$, respectively, at medium velocities. This research signifies a promising advancement for sustainable and efficient hydraulic excavator operations.

The new configuration of independent metering valve (NIMV) system uses three proportional valves that gave been effectively proven to be energy saving compared with a conventional independent metering valve system in the fixed load condition. However, the variable load condition completely affects the accuracy and energy consumption during the operation of excavators. To improve the motion tracking precision and reduce the energy consumption of the NIMV system, a novel control method based on the coordinated control of the pump and the valve is proposed. In detail, the valve is controlled by considering velocity, load force, and position feedback of the cylinder. Meanwhile, velocity feedforward and position feedback methods are used to control the speed of the pump. In addition, a switching mode for the NIMV system is designed to flexibly select the metering modes based on the load and velocity conditions. To confirm the effectiveness of the proposed control method, the co-simulation model is built by using the AMESim and MATLAB software. From the results, the proposed method not only has high trajectory tracking precision with the displacement error of the cylinder at around 3.6% but also achieves up to 6.4% energy saving.