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The Wigner's friend thought experiment has gained a resurgence of interest in recent years thanks to no-go theorems that extend it to Bell-like scenarios. One of these, by us and co-workers, showcased the contradiction that arises between quantum theory and a set of assumptions, weaker than those in Bell's theorem, which we named 'Local Friendliness'. Using these assumptions, it is possible to arrive at a set of inequalities for a given scenario, and, in general, some of these inequalities will be harder to violate than the Bell inequalities for the same scenario. A crucial feature of the extended Wigner's friend scenario in our aforementioned work was the ability of a superobserver to reverse the unitary evolution that gives rise to their friend's measurement. Here, we present a new scenario where the superobserver can interact with the friend repeatedly in a single experimental instance, either by asking them directly for their result, thus ending that instance, or by reversing their measurement and instructing them to perform a new one. We show that, in these scenarios, the Local Friendliness inequalities will always be the same as Bell inequalities. [ABSTRACT FROM AUTHOR]

The paper is dedicated to investigate the impact of the blade trailing edge device on helicopter rotor performance. The study meticulously examines the aerodynamic characteristics of various proposed models during hover flight in order to identify the optimal blade design that fulfils specific requirements. The primary objectives encompass maximizing thrust force generation while simultaneously minimizing the formation of vortices near the trailing edge. Achieving these objectives leads to the creation of a more stable system during helicopter operation. Both Computational Fluid Dynamics (CFD) and theoretical approaches were employed to conduct this research, simulating the behavior of a two-bladed rotor akin to the configuration commonly found in Bell 212 helicopters. The numerical simulations and subsequent discussions encompassed various critical aspects, including the thrust coefficient, pressure distribution, and airflow patterns. Ultimately, the investigation seeks to propose an innovative approach that enhances the overall aerodynamic performance of helicopters during hover flight. [ABSTRACT FROM AUTHOR]

Due to the importance of understanding the aeroacoustics of rotorcraft with continually changing noise sources, this paper presents a new technique for source separation from ground-based acoustic measurements. The source separation process is based on combining a time-domain de-Dopplerization method with the Vold--Kalman order tracking filter approach. This process can extract rotor harmonic noise even when the sources are continuously changing with time, including impulsive events such as blade--vortex interaction noise. The advantage of this approach over traditional methods such as harmonic averaging is that the phase and amplitude relationship of acoustic signals is preserved throughout the extraction process. The approach is applied to the measured acoustic data from a Bell 430 helicopter. The measured data were separated into main rotor harmonic, tail rotor harmonic, and broadband residual components. For steady-state conditions, the extracted components could be depropagated to form acoustic hemispheres showing the directivity of the separated main and tail rotor components. The source separation process was also applied to a maneuvering flight condition. Each component has different pulse shapes and directivity trends, consistent with aeroacoustic theory. [ABSTRACT FROM AUTHOR]

Qubits, as we know, have great benefits as compared to classical bits in computing, research and technology; if these qubits are replaced by qudits, the technological constraints can be further diluted, and more advantages can be gained. In this article, we motivate the reader as to what happens when we go from a quantum world of qubits to a world of qudits. Elementary mathematical analysis of the transformation between the computational basis of qudits and the generalized qudit Bell state basis are derived. In reverence to the overwhelming properties of qudits, we give a detailed discussion of the most generalized quantum teleportation protocol using qudits. From the pedagogical angle, we provide rigorous, indepth calculations for the special case of qutrits. Last but not least, an epigrammatic representation of quantum teleportation is provided to sharpen the reader's understanding. [ABSTRACT FROM AUTHOR]

Compared with spray gun spraying, electrostatic spray rotating bell (ESRB) spraying can provide better film forming quality and higher adhesion rate, which is more suitable for the automobile painting. However, the complexity of the automobile surface geometry and the spray pattern produced by ESRB painting makes the trajectory planning and the determination of spraying parameters challenging. This research presents a coating thickness distribution model for ESRB atomizer with uniform motion and establishes a parametric model to express the functional relationship between the thickness distribution model and atomizer parameters. The proposed parametric model aims to provide a guideline for the determination of spraying parameters in the process of off-line programming in the painting industry. Firstly, a novel feature points fitting distribution model was established based on the characteristics of ESRB uniform linear spraying coating. The model can fully visualize the cumulative profile characteristics of coatings. Secondly, the orthogonal experiment, multilevel and multifactor, was designed to analyze the variation of feature points with the painting parameters. Then, based on the requirements of the spraying process, an objective function is established for the coating thickness and other indicators of each area, and a genetic algorithm is used to solve it, so as to determine the ESRB spraying parameters. Finally, three simulation experiments show that the new model is effective and has high prediction accuracy, which can be effectively applied to the ESRB spraying system. [ABSTRACT FROM AUTHOR]

Compared with spray gun painting, electrostatic spraying rotating bell (ESRB) painting can provide better film-forming quality and higher adhesion rate, which is more suitable for automobile base coating. However, the complexity of the spray pattern of the ESRB and the automobile surface geometric makes the spray process planning a more challenging problem. This paper aims to provide a new parameterized model of the ESRB to facilitate the thickness calculation and trajectory planning in the off-line painting programming. Firstly, according to the distribution characteristics of paint particles and the force analysis of adhesion process, a new static deposition rate model—offset asymmetric Gaussian model is proposed on the plane. The parameters in the new model have intuitive practical significance and can fully reflect the characteristics of ESRB coating deposition rate. Then based on the analysis of the relationship between the static model and uniform linear spraying deposition, the static model is established by measuring the layer data of corresponding uniform linear spraying. In order to further simulate the paint thickness on curved surfaces, the projection model with variable spraying distance and deposition point normal deflection is also deduced. Finally, a parameterized static model and sampling points library are established which provide efficient and accurate prediction of static deposition result, and is more suitable for off-line programming. Three different groups of simulation proved that the proposed static deposition rate model has high calculation accuracy for different working conditions and fast simulation speed for different spraying parameters. [ABSTRACT FROM AUTHOR]

To meet the excitation frequency in the range of 0-200 Hz engine mount to achieve better noise, vibration, and harshness performance (NVH). This paper proposes a new bell plate controllable multi-inertia channel MRF (magnetorheological fluid) mount for dynamic characteristic analysis and research. Firstly, designing a multi-flow channel MRF damper and verifying by the experimental method that a larger current can achieve switching and closing of the flow channels. Secondly, the lumped parameter models of controllable multi-inertia channel MRF mount and controllable multi-inertia channels MRF mount with two bell plates and decoupler membrane combinations (new bell plate multi-inertia channel MRF mount) are solved separately, and the dynamic characteristics of the mounts at high and low frequencies are analyzed. Finally, the 3-degree-of-freedom mount system of the 1/4 car model is built to analyze the effects of different inertia channel switching and closing on the relative displacement of the vehicle frame and engine, and the transfer force of the engine to the vehicle frame. The results show that the designed new bell plate controllable multi-inertia channel MRF mount can achieve adjustable dynamic stiffness and damping in the frequency range of 0-50 Hz, and has a small dynamic stiffness value in the range of 50 Hz-200 Hz. Therefore, the designed MRF mount can achieve wide frequency vibration isolation. [ABSTRACT FROM AUTHOR]

This study investigated the use of computer vision–based algorithms for detecting needle-type instrument readings in the cockpit of an aerial vehicle. A flight data recorder plays a crucial role in aviation safety investigations and flight operation review. In practice, not all aerial vehicles are equipped with flight data recorders, and this poses problems in the retrieval of instrument readings during investigations. Installing a lightweight recorder such as a camera in the cockpit to record the instrument panel is a solution to the mentioned problem. Although recorded flight data can be retrieved through human inspection, computer vision–based algorithms enable more rapid and efficient detection. Accordingly, this study developed two computer vision–based algorithms operated in both of the grayscale color space and the value layer of the hue–saturation–value color space. Performance of the four combinations is then compared and the best combination of algorithm along with operation space is suggested. The airspeed meter of a Bell 206 helicopter was selected to test the proposed detection algorithm in this study. GPS data and human inspection results were used as references. Herein, experimental results are presented, performance of algorithms is discussed, and conclusions are provided. This study contributes to aviation safety investigations and flight operation review involving aerial vehicles that are not equipped with flight data recorders. [ABSTRACT FROM AUTHOR]

In this paper, a novel semiquantum private comparison (SQPC) protocol based on single kind of Bell states is proposed, which allows two classical parties to judge the equality of their private inputs securely and correctly under the help of a semi-honest third party (TP) who possesses complete quantum capabilities. TP is allowed to misbehave on her own but cannot conspire with anyone else. Our protocol needs none of unitary operations, quantum entanglement swapping or the reordering operations. Moreover, our protocol only needs to prepare single kind of Bell states as initial quantum resource. Detailed security analysis turns out that our protocol is secure against various outside and participant attacks. Compared with most of the existing SQPC protocols based on Bell states, our protocol is more feasible in practice. [ABSTRACT FROM AUTHOR]

The aim of this paper is to establish a new identity between derangement numbers and Bell numbers. Two known identities can be recovered. We provide a combinatorial interpretation for the new identity and a representation of the derangement numbers in terms of the determinants of Hessenberg matrices. [ABSTRACT FROM AUTHOR]

Frequency domain system identification of higher order models for the Bell 412 helicopter was performed. First, a frequency response database was derived from flight-test data. For hover, a combination of sweep and 2311-multistep maneuvers had to be used to achieve good results. In addition to the classical six-DoF (degrees of freedom) rigid body states, the identified hover model includes dynamic inflow, rotor coning dynamics, and uses a Padé approximation for the influence of engine dynamics, to improve the response in the vertical axis. The forward flight (60 kn) model includes as extension first-order flapping dynamics, mainly to improve the roll and pitch response. Besides the simple Padé approach used in the hover model, two different engine model structures were investigated but they provided no significant improvement compared to the Padé solution when coupled to the rigid-body model. Finally, a method derived from feed forward principles of model following control is shown, to use the identified hover model to analytically derive an "input filter" correction that improves the fidelity of a linearized FLIGHTLAB simulation model. [ABSTRACT FROM AUTHOR]