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Currently, tissue product producers try to meet consumers' requirements to retain their loyalty. In perforated products, such as toilet paper, these requirements involve the paper being portioned along the perforation line and not outside of it. Thus, it becomes necessary to enhance the behavior of the perforation line in perforated tissue papers. The current study aimed to verify if the perforation line for 0° (the solution found in commercial perforated products) is the best solution to maximize the perforation efficiency. A finite element (FE) simulation was used to validate the experimental data, where the deviations from the experiments were 5.2% for the case with a 4 mm perforation length and 8.8% for a perforation of 2 mm, and optimize the perforation efficiency using the genetic algorithm while considering two different cases. In the first case, the blank distance and the perforation line angle were varied, with the best configuration being achieved with a blank distance of 0.1 mm and an inclination angle of 0.56°. For the second case, the blank distance was fixed to 1.0 mm and the only variable to be optimized was the inclination angle of the perforation line. It was found that the best angle inclination was 0.67°. In both cases, it was verified that a slight inclination in the perforation line will favor partitioning and therefore the perforation efficiency. [ABSTRACT FROM AUTHOR]

The purpose of this note is to discuss how paper folding can be used to find the exact trigonometric ratios of the following four angles: 22.5°, 67.5°, 27°, and 63°. [ABSTRACT FROM AUTHOR]

The thin-walled tubular deployable composite boom (DCB) can realize folding and deploying functions, and it has a good application prospect in space field. This paper investigates the folding behaviour of the tubular DCB by analytical modeling. Based on the Archimedes' helix, the geometrical model of the DCB was established. By combining equilibrium equation and energy principle, an analytical model to predicted the folding moment versus rotational displacement of the DCB was presented. The failure indices in the equal-sense and opposite-sense folding processes were calculated utilizing Tsai‐Hill and maximum stress criteria. Analytical results agreed well with experimental and numerical results. At last, the influence of geometric parameters (i.e., radius, central angle and thickness of cross-section) on the folding behaviour of the DCB was further studied using the analytical model. [Display omitted] • An analytical model is presented to predict the folding behaviour of the deployable composite boom (DCB). • Failure indices are calculated using two criteria in equal-sense and opposite-sense folding processes. • The analytical model is validated against experimental and numerical results, showing good prediction accuracy. • Geometric parameters (radius, central angle, and thickness) significantly affect the folding behavior of the DCB. [ABSTRACT FROM AUTHOR]

The impact between a sphere and flat surface plays a significant role in the granular handling process. A method is proposed to investigate the evolution of interfacial states for the sphere oblique impact with initial spin. Firstly, the sphere with irregular surface structures is applied, and the imprinted surfaces are recorded with a thin carbon paper. Then the interfacial characteristics are analyzed in cases of impact angle, contact material and drop height, etc. The geometrical parameters decrease exponentially with impact angle and include three main stages: plateau, slow decrease and sharp decrease. The motional ratio corresponds to slow increase, steady state and sharp increase. For the no pre-spin, it goes through five interfacial states with impact angle. Comparatively, the forward spin decreases the critical angle, and the backward spin decreases the number of states. Furthermore, the parameters increase linearly with drop height, while the effect on interfacial states is very little. [ABSTRACT FROM AUTHOR]

Compared to the conventional boost power factor correction (PFC) converter, a totem-pole bridgeless PFC has high efficiency because it does not have an input diode rectifier stage, but a current spike may occur when the polarity of the grid voltage changes. This paper proposes a digital control algorithm for bridgeless totem-pole PFC with a simple control structure based on the phase angle of grid voltage. The proposed algorithm has a PI-based double-loop control structure and performs DC-link voltage and input inductor current control. Rectifying switches operate based on the proposed rectification algorithm using phase angle information calculated through a single-phase phase-locked loop (PLL) to prevent current spikes. The feed-forward duty ratio value is calculated according to the polarity of the grid voltage and added to the double-loop controller to perform appropriate power factor control. The performance and feasibility of the proposed control algorithm are verified through a 3 kW hardware prototype. [ABSTRACT FROM AUTHOR]

Displays in cars is one of the hottest topics in the automotive industry and highest (image) quality is a must. Therefore, evaluation is excessive and OEM‐specific specs are not efficient. The Displayforum (DFF) innovated optical specifications and requirements by involving experts along the value chain and dedicated methods for automotive. [ABSTRACT FROM AUTHOR]

The most effective way to improve display visibility in ambient light is to suppress the reflectance of the display. After conducting a thorough analysis of the factors contributing to unwanted reflection, specific layers were identified that required improvement. Subsequently, these elements were carefully optimized, resulting in a significant reduction of internal reflection to 0.53% for our 12.3" FFS‐mode prototype, compared to 1.12% in conventional LCDs. This improvement was achieved without the use of circular polarizers and has been demonstrated to provide excellent visibility in bright ambient conditions while allowing for reduced backlight brightness and lower power consumption. [ABSTRACT FROM AUTHOR]

Reflective LCDs have a great advantage of low power consumption, but the brightness is not consistently sufficient because ambient light is used as a light source. To increase light efficiency, we combined reflective LCDs and the Pancharatnam‐Berry deflector (PBD), a diffractive optical element that controls the propagation of incident light. We confirmed that on‐axis brightness is increased by 2.2 times against the incident collimated light from a polar angle of 30° when compared to a reflective LCD without PBD. [ABSTRACT FROM AUTHOR]

An approximate beam propagation method is proposed as an intuitive simulation of the optics of the Pancharatnam–Berry phase (PPD). Using this method, the limitation of PPD in diffraction efficiency for large diffraction angle is made clear. [ABSTRACT FROM AUTHOR]

We have developed novel cholesteric liquid crystal (Ch‐LC) films creating angle insensitive reflective colors. The wavy alignment formed by rapid change of the helical twisting power (HTP) enables the suppression of color shift with different incident angles. With this approach various decorative films for innovative applications can be created. [ABSTRACT FROM AUTHOR]

Summarizes the construction of paper folding. Method for approximating rational subdivisions or arbitrary angles and line segments; Angle-folding algorithm; Approximating angles, regular polygons and star polygons; Dissection of angles into equal parts.

We propose an integral three‐dimensional (3D) display method using time‐division multiplexing and eye‐tracking technologies to enhance the maximum pixel density and viewing zone angle of 3D images. We prototyped a display system and confirmed that 3D images with high pixel density and wide viewing zone angle can be displayed. [ABSTRACT FROM AUTHOR]

With ever more stringent color‐gamut requirements in displays (e.g., BT.2100), there is growing demand for OLEDs with narrowband emission. However, many efficient emitters reported to date show spectrally broad luminescence. Micro‐cavity OLEDs offer narrow linewidth but suffer from changes in spectrum with observation angle. To overcome these limitations, we hybridize microcavity and exciton states in an efficient OLED, thus creating strongly coupled polariton states that inherit the angle insensitivity of excitons and the narrow linewidth of the microcavity. Using assistant strong‐coupling layers located away from the recombination zone yields efficient OLEDs with FWHM <20 nm and angle shift <10 nm @60° tilt. [ABSTRACT FROM AUTHOR]

This paper presents an example of how paper folding can be used in a geometry class to support conceptual understanding. Specifically, it explains an activity that constructs a rhombus and explores its attributes by using paper folding. The steps of constructing a rhombus are described and some discussion questions are given to consolidate understanding. [ABSTRACT FROM AUTHOR]

A novel beam steering angle expander is demonstrated by cascading two polymeric liquid crystal polarization lenses with different diopters. The lens module performs as a planar telescope, which is featured as lightweight, low cost, and high precision. The magnifier offers wide‐angle continuous steering when integrated with an active fine‐angle beam steerer. [ABSTRACT FROM AUTHOR]

We have developed a large size reflective LCD providing good visibility under bright circumstances and high productivity. To obtain wide viewing angle reflective mode, the panel design for the 2‐domain aligned LCD with UV2 A technology was examined. We adopted it into a prototype and successfully fabricated a 90‐inch TFT LCD. [ABSTRACT FROM AUTHOR]

During the machine vision inspection of the inner section of bottle caps within pharmaceutical packaging, the unique conca bottom and convex side walls often create obstructions to the illumination. Consequently, this results in challenges such as irregular background and diminished feature contrast in the image, ultimately leading to the misidentification of defects. As a solution, a vision system characterized by a Low-Angle and Large Divergence Angle (LALDA) is presented in this paper. Using the large divergence angle of LED, combined with low-angle illumination, a uniform image of the side wall region with bright-field characteristics and a uniform image of inner circle region at the bottom with dark-field characteristics are obtained, thus solving the problems of light being obscured and brightness overexposure of the background. Based on the imaging characteristics of LALDA, a multi-channel segmentation (MCS) algorithm is designed. The HSV color space has been transformed, and the image is automatically segmented into multiple sub-regions by mutual calculation of different channels. Further, image homogenization and enhancement are used to eliminate fluctuations in the background and to enhance the contrast of defects. In addition, a variety of defect extraction methods are designed based on the imaging characteristics of different sub-regions, which can avoid the problem of over-segmentation in detection. In this paper, the LALDA is applied to the defect detection inside the cap of capsule medicine bottle, the detection speed is better than 400 pcs/min and the detection accuracy is better than 95%, which can meet the actual production line capacity and detection requirements. [ABSTRACT FROM AUTHOR]

The article is based on the lecture ‘Mathematics teacher training from the perspective of STEM – a particular case’ given by its author at the ATCM 2023 conference and is an extension of a related paper that was published in the conference proceedings. It further develops the idea that the task of teacher training schools is to create a suitable environment for the provision of education, impulses for the development of the necessary knowledge and skills, as well as to support these. It provides a detailed description of specific creative activities for future teachers, which develop their awareness of the applicability of mathematics in solving real problems and knowledge of its overlap with technology. It is based on historical problems and their context, as presented in the conference paper. Emphasis is placed on the use of computers, especially dynamic geometry software GeoGebra, to model the geometric nature of given problems and for their effective solution. [ABSTRACT FROM AUTHOR]

The edge detection method based on the magnetic gradient tensor data plays an important role in magnetic exploration because it is free from geomagnetic interference and contains more abundant information. This paper proposes a new anomaly edge detection method using the magnetic gradient tensor components. The model is established to compare with other methods, such as directional total horizontal derivative (THDz), analytical signal (AS), tilt angle, theta map, and so on, under conditions of vertical magnetization, oblique magnetization, and noise interference. Through the study of the anomaly distribution of the rectangular model, it is observed that the edge detection method proposed in this paper is nearly impervious to noise interference, exhibits strong anti-interference capabilities, delivers a high-quality boundary identification effect, and provides greater accuracy in anomaly edges with minimal error. When multiple anomalous bodies are present, the edge detection results are less susceptible to interference from each other, resulting in higher resolution. The efficiency of the algorithm is demonstrated by real magnetic data from some study areas in Jiangxi Province, China. The experimental results show that the proposed method is more precise and accurate than the total horizontal derivative, analytical signal, tilt angle, and theta map methods. [ABSTRACT FROM AUTHOR]

The article offers information on dynamical systems and irrational angle construction by paper-folding. Construction of rational angle to any desired accuracy by folding a strip of paper requires approximating method. The construction uses a periodic sequence composed of two types of folding moves, guided by number-theoretic properties of the angle's fractional representation. The number-theoretic scheme must be replaced by something new, the Folds and Switchfold prescription, in the construction of irrational angles.

Presents several Origami-based mathematical problems. Application of the activity of paper folding in solving math puzzles using the angles, geometric shapes and creases of the paper; Construction of paper shapes based on mathematical rules and parameters provided by the puzzle.

Investigates the limit of angle measures formed by repeatedly folding a strip of paper. What makes the investigation interesting; Steps involved in folding the paper; Lessons students should learn about the angle measures formed by the folded paper; Ways in which teachers can help students to analyze the process.

The mechanical and hydrodynamic phenomena occurring in the refining zones of disc refiners cause fibres to undergo fibrillation. This paper presents a study of the changes occurring during fibre fibrillation as expressed in terms of the fibrillation index when refining pulp with a 10%, 15%, and 20% consistency. The influences of the tangential force of a circular bar and a straight bar on fibre fibrillation were compared. The changes in the tangential force are shown to depend on the angle between the tangent to the cutting edge and the radius from the centre of the disk to the tangency point. Increasing the angle between the tangent to the cutting edge and the radius from the centre of the disk to the tangency point gives higher fibrillation index values. The study revealed a relationship between fibre fibrillation and the strength characteristics of handsheets. [ABSTRACT FROM AUTHOR]

The Republic of Venice was one of the longest-lived states in modern history, and its stability and survival have been studied through many different angles. One of the main research angles is to try and find pivotal moments in its history that explain its eventual demise. In this paper, through the rigorous statistical analysis of a dataset of marriages by nobles in the Republic, we attempt to define a methodology for the detection of these events through mono and multivariate changepoint analysis, validating the proposed methodology through cross-validation of different procedures, as well as matching the results to historical events. Our analysis shows that these changepoints occur with statistical significance and that they match political and historical events. These results can be built upon for a better understanding of the historical causes of the success and failure of the Republic of Venice and, by extension, other states. [ABSTRACT FROM AUTHOR]

Commutation failure is still one of the most common faults in LCC-UHVDC (line commutated converter-based, ultra-high voltage direct current) systems, and if the inverter side, extinction angle, and rectification value remain constant during the fault, it may lead to commutation failure or even continuous commutation failure. Therefore, this paper first analyzes the structure of the LCC-UHVDC system and the mechanism of commutation failure and, on this basis, proposes a commutation failure suppression method based on dynamic tracking of the extinction angle rectification value. The desired DC voltage of the system under fault conditions is calculated based on key state quantities such as the AC voltage RMS value, the extinction angle, and the leading angle during the fault process. The compensation amount is obtained by comparing the desired DC voltage with the actual DC voltage and superimposition on the extinction angle rectification value in the inverter extinction angle control. When there is a risk of commutation failure, dynamically adjusting the extinction angle setting value according to the compensation value is beneficial for the rapid and stable recovery of the extinction angle, reducing the probability of commutation failure. A bipolar neutral ground LCC-UHVDC testing model system is established in PSCAD/EMTDC for simulation verification to show that the proposed improved control strategy effectively reduces the probability of commutation failure and significantly improves the stable operation characteristics of the LCC-UHVDC system. [ABSTRACT FROM AUTHOR]

Many materials machine in either a ductile or brittle manner depending on the cutting conditions. This paper identifies the conditions which allow perspex to be machined in a ductile manner. A quantitative assessment is made of the effects of cutting speed and feed rate on the ductile-brittle transition when turning with a tool having a 30degrees rake angle. [ABSTRACT FROM AUTHOR]

In this paper, flow over a cluster of three equally spaced circular cylinders was studied by numerical simulation based on the turbulence model k-kl-ω for two incidence angles β = 0° and 60°, at different Reynolds numbers, and flow interference pattern characteristics between cylinders, characteristics of force parameters, and Strouhal number of each cylinder with different spacing ratios ranging from 1.5 to 4 at Re 8 × 104, 2 × 105 and 2 × 106 were obtained. Analyzing the flow field around three cylinders, the following results have been obtained: (1) at incidence angle β = 0° and 60°, the wake was nearly symmetrical if S/D ≥ 2.0; (2) at β = 60°, S/D = 1.5, and Re = 2 × 105, an asymmetric periodic flow pattern occurred in the wake region which produced a significant effect on the surface mechanical parameters and Strouhal number, and this was observed for the first time. The periodic flow regime of the wake region also occurred at S/D = 1.35 and 1.5, without the same phenomenon at S/D = 1.7 and 2.0; this phenomenon is described for the first time in this paper; (3) the phenomenon of periodic flow regime in the wake region was intrinsic and related to Reynolds number and space ratio. In addition, the characteristics of force parameters of three cylinders were mainly affected by the interference between cylinders, at 1.5 < S/D < 4, which indicated that the drag coefficient of three cylinders reduces with different Reynolds numbers and increases with enlargement of the spacing ratio for upstream cylinders at incidence angle 0°. At incidence angle 60° and S/D = 1.5~4, the Strouhal number decreases with the enlargement of spacing ratio for the upstream cylinders, but the Strouhal number increases for the downstream cylinder, which is another prominent flow interference influence. The results indicated the effect of flow interference between cylinders subjected to a cross flow over a cluster of three equally spaced cylinders, considering the flow pattern, surface mechanical parameters and Strouhal number, which should be considered in the establishment of standard design codes in fields such as offshore wind turbine engineering for flow interference around groups of cylinders. [ABSTRACT FROM AUTHOR]

A hybrid drone called a biplane quadrotor operates in both low (during the horizontal flight) and high (transition maneuver) Angle of Attack (AoA). So, this paper focuses on enhancing aerodynamic force during the transition maneuver. Synthetic Jet actuators (SJAs) can modify airfoil shapes virtually, so either the flow reattaches or flow separation will be delayed. This delay can enhance the aerodynamic force. In this paper, CFD analysis is performed using Ansys Fluent to study the impact of SJA on NACA 0015 airfoil at high (30°) AoA. This study aims to find the best location of SJA for high AoA to get maximum lift enhancement. The outcome of this study reveals that at 85 %, we can get maximum enhancement in the lift. [ABSTRACT FROM AUTHOR]

In order to enhance the stability of the tilt transition process, a new configuration of Quad-Tiltrotor UAV was presented in this paper. Firstly, numerical simulation was used to calculate and analyze the aerodynamic interaction between the front rotor/fuselage/rear rotor during the transition state mode. The calculation model of the isolated rotor, front-rear rotor, front rotor-fuselage, and front rotor-rear rotor-fuselage combination states are established. Besides, the effects of pitch, roll, and yaw moment on the fuselage at different tilt angles are analyzed. It is concluded that the front rotor is the leading factor in the aerodynamic interference of the whole UAV in the different combination states. The research results can provide a reference for the optimization design of the overall layout, structure, and flight control strategy of the cross-shaped quad-tiltrotor UAV, and can also provide solutions for the logistics application of urban air traffic. [ABSTRACT FROM AUTHOR]

In view of the influence of the inclination and variable section on the pile stability and bearing capacity, this paper introduces particle image velocimetry (PIV) technology, and designs a transparent soil visualization model test. The experimental results show that, when the pile has a variable cross-section and inclination angle, the friction resistance on both sides of the pile increases. The vertical-load-carrying capacity of the 2% and 4% inclined piles with a variable cross-section is greater than that of the piles with inclinations greater than 8%. For model piles with the degrees of inclination of 2% and 4%, the variable-section inclined piles with diameters of 17 mm and 15 mm show significantly less settlement than the equal-section inclined piles. For the model pile with an inclination of 8%, the settlement of the inclined piles with a variable cross-section diameter of 17 mm is slightly smaller than that of the equal cross-section inclined piles. The change in variable cross-section and inclination angle has a large effect on the soil displacement around the pile, and the conclusions of this paper can provide guidance for the engineering application of variable cross-section piles. [ABSTRACT FROM AUTHOR]

This paper aims to improve the steering performance of the Ackermann personal mobility scooter based on a new meta-heuristic optimization algorithm named Differential Harris Hawks Optimization (DHHO) and the modeling of the steering encoder. The steering response in the Ackermann mechanism is crucial for automated driving systems (ADS), especially in localization and path-planning phases. Various methods presented in the literature are used to control the steering, and meta-heuristic optimization algorithms have achieved prominent results. Harris Hawks optimization (HHO) algorithm is a recent algorithm that outperforms state-of-the-art algorithms in various optimization applications. However, it has yet to be applied to the steering control application. The research in this paper was conducted in three stages. First, practical experiments were performed on the steering encoder sensor that measures the steering angle of the Landlex mobility scooter, and supervised learning was applied to model the results obtained for the steering control. Second, the DHHO algorithm is proposed by introducing mutation between hawks in the exploration phase instead of the Hawks perch technique, improving population diversity and reducing premature convergence. The simulation results on CEC2021 benchmark functions showed that the DHHO algorithm outperforms the HHO, PSO, BAS, and CMAES algorithms. The mean error of the DHHO is improved with a confidence level of 99.8047% and 91.6016% in the 10-dimension and 20-dimension problems, respectively, compared with the original HHO. Third, DHHO is implemented for interactive real-time PID tuning to control the steering of the Ackermann scooter. The practical transient response results showed that the settling time is improved by 89.31% compared to the original response with no overshoot and steady-state error, proving the superior performance of the DHHO algorithm compared to the traditional control methods. [ABSTRACT FROM AUTHOR]

Lane line images have the essential attribute of large-scale variation and complex scene information, and the similarity between adjacent lane lines is high, which can easily cause classification errors. And remote lane lines are difficult to recognize due to visual angle changes in width. To address this issue, this paper proposes an effective lane detection framework, which is a hybrid feature fusion network that enhances multiple spatial features and distinguishes key features throughout the entire lane line segment. It enhances and fuses lane line features at multiscale to enhance the feature representation of lane line images, especially at the far end. Firstly, in order to enhance the correlation of multiscale lane features, a multi-head self attention is used to construct a multi-space attention enhancement module for feature enhancement in multispace. Secondly, a spatial separable convolutional branch is designed for the jumping layer structure connecting multiscale lane line features. While retaining feature information of different scales, important lane areas in multiscale feature information are emphasized through the allocation of spatial attention weights. Finally, considering that lane lines are elongated areas in the image, and the background information in the image is much more abundant than lane line information, the flexibility of traditional pooling operations in capturing widely existing anisotropic contexts in actual environments is limited. Therefore, before embedding feature output branches, strip pooling is introduced to refine the representation of lane line information and optimize model performance. The experimental results show that the accuracy on the TuSimple dataset reaches 96.84%, and the F1 score on the CULane dataset reaches 75.9%. [ABSTRACT FROM AUTHOR]

At present, PPF-based point cloud recognition algorithms can perform better matching than competitors and be verified in the case of severe occlusion and stacking. However, including certain superfluous feature point pairs in the global model description would significantly lower the algorithm's efficiency. As a result, this paper delves into the Point Pair Feature (PPF) algorithm and proposes a 6D pose estimation method based on Keypoint Pair Feature (K-PPF) voting. The K-PPF algorithm is based on the PPF algorithm and proposes an improved algorithm for the sampling point part. The sample points are retrieved using a combination of curvature-adaptive and grid ISS, and the angle-adaptive judgment is performed on the sampling points to extract the keypoints, therefore improving the point pair feature difference and matching accuracy. To verify the effectiveness of the method, we analyze the experimental results in scenes with different occlusion and complexity levels under the evaluation metrics of ADD-S, Recall, Precision, and Overlap rate. The results show that the algorithm in this paper reduces redundant point pairs and improves recognition efficiency and robustness compared with PPF. Compared with FPFH, CSHOT, SHOT and SI algorithms, this paper improves the recall rate by more than 12.5%. [ABSTRACT FROM AUTHOR]

In order to analyze the relay action process from an imaging perspective and further investigate the bounce phenomenon of relay contacts during the contact process, this paper utilizes a high-speed shooting platform to capture images of relay action. In light of the situation where the stationary contact in the image is inclined and continuously changing, a rotation template matching algorithm based on adaptive weight is proposed. The algorithm identifies and obtains the inclination angle of the stationary contact, enabling the study of the relay contact bounce process. By extracting contact bounce distance data from the images, a bounce process curve is plotted. Combined with the analysis of the contact bounce process, the reasons for the bounce are explored. The results indicate that the proposed rotation template matching algorithm can accurately identify stationary contacts and their angles at different angles. By analyzing the contact status and bounce process of the relay contacts in conjunction with the relay structure, parameters such as the bounce time, bounce height, and time required to reach the maximum distance can be calculated. Additionally, the main reason for contact bounce in the relay studied in this paper is the limitation imposed on the continued movement of the stationary contact by the presence of the relay brackets when the kinetic energy of the contact is too high. This phenomenon occurs during the first vibration peak in the vibration process after the moving contact contacts the stationary contact. The research results provide a reference for further studying the relay contact bounce process, optimizing relay structure, and suppressing contact bounce. [ABSTRACT FROM AUTHOR]

In recent years, with the development of DC transmission projects in China, the number of converter stations has increased. Fire accidents in converter stations have also become more frequent. Transformer insulating paperboard, as a typical combustible material in converter station equipment, poses a greater fire risk. So in this paper, flame spreading behaviors, including experimental visual characteristics, fire spreading rate, mass loss with time and mass loss rate, of transformer insulating paperboard with different thickness and different inclined angles are investigated. The results show that: (1) In downwards flame spread, that is, in the case of positive angle, the flame height and width gradually decrease with the increase of angle; in the case of negatively inclined angles, the flame length shows an increasing trend with the decrease of inclined angles, and the flame thickness gradually becomes thinner. (2) In upwards flame spread, that is, in the case of negative angle, the fire spreading rate of the insulating paperboard decreases sharply with the increase of the angle; In the case of a positively inclined angle, the change of flame spreading rate is not obvious with the increase of inclined angles as compared with the conditions in negative angles. The paperboard thickness also has a significant impact on the flame spreading rate, and the flame spreading rate will decrease significantly with the increase of paperboard thickness. (3) In upwards flame spread, the mass loss rate of insulating paperboard will decrease significantly with the increase of inclined angles; in downwards flame spread, the change of mass loss rate is not obvious with the increase of inclined angles as compared with those in condition of negative angles. At the same time, the mass loss rate will increase significantly with the increase of paperboard thickness. (4) The mass loss rate and fire spread rate of the insulating paperboard have a strong correlation with the flame length and the length of the pyrolysis zone. A heat transfer process model about characteristic length scale and mass loss rate is established. In order to simplify the model, a dimensionless relation about angle is defined to replace the feature length and to explore the relationship between angle and mass loss rate. Based on the inherent relationship between fire spread rate and mass loss rate, the relationship between fire spread rate and angle is found. And the result shows satisfactory agreement between the predictions and experimental results. [ABSTRACT FROM AUTHOR]

Based on real-time access to response information on wide-area tributaries, in order to assess the system stability more quickly, this paper combines the simplified branch transient transmission capability (sBTTC) index and the largest Lyapunov exponent (MLE). An online identification method for transient power angle stability is proposed. Firstly, the method is based on a two-machine system to study the consistency of the power angle difference between the two ends of the critical branch and the change of the phase difference of the fleet. Secondly, the transient power angle stability problem is transformed into the MLE analysis problem according to the change rule of sBTTC index of the key branch. Then, by combining the characteristics of MLE curve and sBTTC index curve, the transient power angle stability criterion is given. Finally, the proposed method is verified and analysed by simulation examples. The method has strong industrial applicability because it does not need system model, the information source is easy to measure, it has strong anti-noise ability, and it overcomes the defect of the traditional method that needs to set a fixed symbolic observation window. [ABSTRACT FROM AUTHOR]

Featured Application: Path Tracking Control for Autonomous Driving. This paper presents a method to design a path tracking controller with a constraint on tire slip angles under low-friction road conditions. On a low-friction road surface, a lateral tire force is easily saturated and decreases as a tire slip angle increases by a large steering angle. Under this situation, a path tracking controller cannot achieve its maximum performance. To cope with this problem, it is necessary to limit tire slip angles to a value where the maximum lateral tire force is achieved. The most commonly used controllers for path tracking, linear quadratic regulator (LQR) and model predictive control (MPC), are adopted as a controller design methodology. The control inputs of LQR and MPC are front and rear steering angles and control yaw moment, which have been widely used for path tracking. The constraint derived from tire slip angles is imposed on the steering angles of LQR and MPC. To fully verify the performance of the path tracking controller with the constraint on tire slip angles, a simulation is conducted on vehicle simulation software. From the simulation results, it is shown that the path tracking controller with the constraint on tire slip angles presented in this paper is quite effective for path tracking on low-friction road surface. [ABSTRACT FROM AUTHOR]

This paper introduces a new kind of quasicrystal by Fibonacci-spacing a multigrid of a certain symmetry, like H 2 , H 3 , T 3 , etc. Multigrids of a certain symmetry can be used to generate quasicrystals, but multigrid vertices are not a quasicrystal due to arbitrary closeness. By Fibonacci-spacing the grids, the structure transit into an aperiodic order becomes a quasicrystal itself. Unlike the quasicrystal generated by the dual-grid method, this kind of quasicrystal does not live in the dual space of the grid space. It is the grid space itself and possesses quasicrystal properties, except that its total number of vertex types are not finite and fixed for the infinite size of the quasicrystal but bounded by a slowly logarithmic growing number. A 2D example, the Fibonacci pentagrid, is given. A 3D example, the Fibonacci icosagrid (FIG), is also introduced, as well as its subsets, the Fibonacci tetragrid (FTG). The FIG can be thought of as a golden composition of five sets of FTGs. The golden composition procedure is another way to transit a random structure into aperiodic order, and the associated rotational angle is the same as the angle that resolves the geometric frustration for the H 3 tetrahedral clusters. The FIG resembles another quasicrystal that is the same golden composition of five quasicrystals that are cut and projected and sliced from the E 8 lattice. This leads to further exploration in mapping the FIG to the E 8 lattice, and the results will be published following this paper. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to investigate a novel impact time control guidance (ITCG) law based on the sliding mode control (SMC) for a nonmaneuvering target using the predicted interception point (PIP). Design/methodology/approach: To intercept the target with the minimal miss distance and desired impact time, an estimation of time-to-go is introduced. This estimation results in a precise impact time for multimissiles salvo attack the target at the same time. Even for a large lead angle, the desired impact time is achieved by using the sliding mode and Lyapunov stability theory. The singularity issue of the proposed impact time guidance laws is also analyzed to achieve an arbitrary lead angle with the desired impact time. Findings: Numerical scenarios with desired impact time are presented to illustrate the performance of the proposed ITCG law. Comparison with the state-of-art impact time guidance laws proves that the guidance law in this paper can enable the missile to intercept the target with minimal miss distance and final impact time error. This method enables multiple missiles to attack the target simultaneously with different distances and arbitrary lead angles. Originality/value: An ITCG law based on sliding mode and Lyapunov stability theory is proposed, and the switching surface is designed based on a novel estimation time-to-go for the missile to intercept the target with minimal miss distance. To intercept the target with initial arbitrary lead angles and desired impact time, the authors analysis the singular issue in SMC to ensure that the missile can intercept the target with arbitrary lead angle. The proposed approach for a nonmaneuvering target using the PIP has simple forms, and therefore, they have the superiority of being implemented easily. [ABSTRACT FROM AUTHOR]

Accurate road network information is required to study and analyze the relationship between land usage type and land subsidence, and road extraction from remote sensing images is an important data source for updating road networks. This task has been considered a significant semantic segmentation problem, given the many road extraction methods developed for remote sensing images in recent years. Although impressive results have been achieved by classifying each pixel in the remote sensing image using a semantic segmentation network, traditional semantic segmentation methods often lack clear constraints of road features. Consequently, the geometric features of the results might deviate from actual roads, leading to issues like road fractures, rough edges, inconsistent road widths, and more, which hinder their effectiveness in road updates. This paper proposes a novel road semantic segmentation algorithm for remote sensing images based on the joint road angle prediction. By incorporating the angle prediction module and the angle feature fusion module, constraints are added to the angle features of the road. Through the angle prediction and angle feature fusion, the information contained in the remote sensing images can be better utilized. The experimental results show that the proposed method outperforms existing semantic segmentation methods in both quantitative evaluation and visual effects. Furthermore, the extracted roads were consecutive with distinct edges, making them more suitable for mapping road updates. [ABSTRACT FROM AUTHOR]

In this paper, we show how the usual change of tangent altitude associated with atmospheric refraction is inseparably connected to a variation of the observed apparent intensity, for extended and pointlike sources. We demonstrate, in the regime of weak refraction angles, that atmospheric optical dilution and image deformation are strictly concomitant. The approach leads to the integration of a simple differential equation related to the observed transmittance in the absence of other absorbing molecules along the optical path. We successfully applied the proposed method to the measurements performed by two past occultation experiments: GOMOS for stellar and ORA for solar occultations. The developed algorithm (named ARID) will be applied to the imaging of solar occultations in a forthcoming pico-satellite mission. [ABSTRACT FROM AUTHOR]

The Steward platform is employed in dynamic simulation of a number of controlled mechanical systems, in control of the active surface of a telescope mirror, and other constructions. Position and orientation of this platform is regulated by changing the lengths of its supporting bars, and corresponding change of their angles relative to the base. Viable motions of the platform depend on how the bars are hinged to the base and to the platform. This paper studies dynamics and stabilization of a platform leaning on three bars of controlled length under wind loads. This problem is of interest for design of active mirror surfaces of radio telescopes. [ABSTRACT FROM AUTHOR]

The article discusses the issue related to evaluation of basic friction angle ɸ in context to the saw-cut rock surfaces. It mentions S.R. Hencher, scientist in context to the contribution of useful references related to the basic friction angle with low values, and highlights the work of Hencher regarding the laboratory estimatation of the angle for the input of the formulation of peak shear strength criterion.

Inspired by the tip feathers of soaring birds, the device of tip sails was designed and installed on the wing to achieve drag reduction. The influences of design parameters including cant angles, toe angles and twist angles on aerodynamic characteristics of tip sails were investigated through 77 cases of 11 configurations at 7 different angles of attack. According to the results grouped, the optimal cant angles (30, 15, 0) were determined. By adjusting the toe angles, drag reduction can be improved under different flight conditions. The decreasing twist angles can inhibit flow separation on sail surface. The optimal toe angles (18, 15, 12) and twist angles (12, 9, 6) resulted in the weakest flow separation. Ensuring that the twist angle of each sail is 6° less than that of the corresponding toe angle can effectively inhibit flow separation on the sail surface. The tip sails can also split and weaken the wingtip vortex. In addition, in the validation of the numerical method, we also investigate the influence of numerical schemes and turbulence models on the results of wingtip vortex flow. In the cases with unstructured meshes, the third-order finite volume scheme had higher computational efficiency than the traditional second-order finite volume scheme in obtaining grid independent solutions, and the turbulence model with rotation correction can improve the calculation accuracy of the wingtip vortex flow. The results of this paper provide a valuable reference for the design of tip sails. [ABSTRACT FROM AUTHOR]

Existing vehicle-road models used for road tracking do not take into account the side slip angle, which leads to a reduction in road tracking accuracy in scenarios where the vehicle is at a large side slip angle, such as an emergency lane change. Consequently, this study presents a path-tracking control technique based on the T-S fuzzy model of heading angle vehicle autonomy. In this paper, based on the yaw angle-based vehicle tracking model, a heading angle-based tracking model considering the side slip angle is constructed. Second, since the vehicle speed varies with time, this paper selects the membership function of the vehicle speed to establish the T-S fuzzy model of autonomous vehicle based on the yaw angle and heading angle, respectively, and ensures the robustness and stability over the whole parameter space by the linear parameter variation robust H ∞ controller. Then, cost functions based on the yaw angle and heading angle augmented error systems are created separately to optimize the system's overall performance. Ultimately, simulation and experimentation confirm that the algorithm for control, which is based on the fuzzy model of the heading angle vehicle, has superior autonomous trajectory performance. [ABSTRACT FROM AUTHOR]

In response to the numerous challenges faced by traditional human pose recognition methods in practical applications, such as dense targets, severe edge occlusion, limited application scenarios, complex backgrounds, and poor recognition accuracy when targets are occluded, this paper proposes a YOLO-Pose algorithm for human pose estimation. The specific improvements are divided into four parts. Firstly, in the Backbone section of the YOLO-Pose model, lightweight GhostNet modules are introduced to reduce the model's parameter count and computational requirements, making it suitable for deployment on unmanned aerial vehicles (UAVs). Secondly, the ACmix attention mechanism is integrated into the Neck section to improve detection speed during object judgment and localization. Furthermore, in the Head section, key points are optimized using coordinate attention mechanisms, significantly enhancing key point localization accuracy. Lastly, the paper improves the loss function and confidence function to enhance the model's robustness. Experimental results demonstrate that the improved model achieves a 95.58% improvement in mAP50 and a 69.54% improvement in mAP50-95 compared to the original model, with a reduction of 14.6 M parameters. The model achieves a detection speed of 19.9 ms per image, optimized by 30% and 39.5% compared to the original model. Comparisons with other algorithms such as Faster R-CNN, SSD, YOLOv4, and YOLOv7 demonstrate varying degrees of performance improvement. [ABSTRACT FROM AUTHOR]

The autonomous navigation of mobile robots contains three parts: map building, global localization, and path planning. Precise pose data directly affect the accuracy of global localization. However, the cumulative error problems of sensors and various estimation strategies cause the pose to have a large gap in data accuracy. To address these problems, this paper proposes a pose calibration method based on localization and point cloud registration, which is called L-PCM. Firstly, the method obtains the odometer and IMU (inertial measurement unit) data through the sensors mounted on the mobile robot and uses the UKF (unscented Kalman filter) algorithm to filter and fuse the odometer data and IMU data to obtain the estimated pose of the mobile robot. Secondly, the AMCL (adaptive Monte Carlo localization) is improved by combining the UKF fusion model of the IMU and odometer to obtain the modified global initial pose of the mobile robot. Finally, PL-ICP (point to line-iterative closest point) point cloud registration is used to calibrate the modified global initial pose to obtain the global pose of the mobile robot. Through simulation experiments, it is verified that the UKF fusion algorithm can reduce the influence of cumulative errors and the improved AMCL algorithm can optimize the pose trajectory. The average value of the position error is about 0.0447 m, and the average value of the angle error is stabilized at about 0.0049 degrees. Meanwhile, it has been verified that the L-PCM is significantly better than the existing AMCL algorithm, with a position error of about 0.01726 m and an average angle error of about 0.00302 degrees, effectively improving the accuracy of the pose. [ABSTRACT FROM AUTHOR]

Persistent Scatterer InSAR (PS-InSAR) technology enables the monitoring of displacement in millimeters. However, without the use of external parameter correction, radar scatterers exhibit poor geopositioning precision in meters, limiting the correlation between observed deformation and the actual structure. The integration of PS-InSAR datasets and building databases is often overlooked in deformation research. This paper presents a novel strategy for matching between PS points and building contours based on spatial distribution characteristics. A convex hull is employed to simplify the building outline. Considering the influence of building height and incident angle on geometric distortion, an adaptive buffer zone is established. The PS points on a building are further identified through the nearest neighbor method. In this study, both ascending and descending TerraSAR-X orbit datasets acquired between 2016 and 2019 were utilized for PS-InSAR monitoring. The efficacy of the proposed method was evaluated by comparing the PS-InSAR results obtained from different orbits. Through a process of comparison and verification, it was demonstrated that the matching effect between PS points and building contours was significantly enhanced, resulting in an increase of 29.2% in the number of matching PS points. The results indicate that this novel strategy can be employed to associate PS points with building outlines without the need for complex calculations, thereby providing a robust foundation for subsequent building risk assessment. [ABSTRACT FROM AUTHOR]

Some passive sensors can provide only relative angles of a signal source. To obtain the signal source location, multiple passive sensors can be constructed into a passive sensor network through communication links. This paper investigates the source localization problem with angle-only measurements in three-dimensional space. First, we present an intersection localization method, which estimates the target position by minimizing the sum of distances between lines formed by angle-only measurements. It has the same target position estimate as the widely used least-squares (LS) method, but with a lower computational cost. Furthermore, considering the differences in measurement accuracy of sensors, the weighted least-squares (WLS) algorithm can achieve better localization performance than the LS method. Unfortunately, since the coefficient matrix and the noise vector are correlated, the WLS method is biased. The bias-compensation WLS (BCWLS) method is also presented in this paper to reduce the bias by estimating the correlation between the coefficient matrix and the pseudolinear noise vector. To evaluate the performance of the presented algorithms, numerical simulations are conducted, indicating that the superiority of the intersection localization method in computational cost and the superiority of the BCWLS method in localization accuracy. [ABSTRACT FROM AUTHOR]