Frame Boundary Research Articles

Monocular Pose Estimation Method for Automatic Citrus Harvesting Using Semantic Segmentation and Rotating Target Detection.

The lack of spatial pose information and the low positioning accuracy of the picking target are the key factors affecting the picking function of citrus-picking robots. In this paper, a new method for automatic citrus fruit harvest is proposed, which uses semantic segmentation and rotating target detection to estimate the pose of a single culture. First, Faster R-CNN is used for grab detection to identify candidate grab frames. At the same time, the semantic segmentation network extracts the contour information of the citrus fruit to be harvested. Then, the capture frame with the highest confidence is selected for each target fruit using the semantic segmentation results, and the rough angle is estimated. The network uses image-processing technology and a camera-imaging model to further segment the mask image of the fruit and its epiphyllous branches and realize the fitting of contour, fruit centroid, and fruit minimum outer rectangular frame and three-dimensional boundary frame. The positional relationship of the citrus fruit to its epiphytic branches was used to estimate the three-dimensional pose of the citrus fruit. The effectiveness of the method was verified through citrus-planting experiments, and then field picking experiments were carried out in the natural environment of orchards. The results showed that the success rate of citrus fruit recognition and positioning was 93.6%, the average attitude estimation angle error was 7.9°, and the success rate of picking was 85.1%. The average picking time is 5.6 s, indicating that the robot can effectively perform intelligent picking operations.

Bubbles and drops between circular frames: shape, force and stability analysis.

Interactions between bubbles and drops play an important role in many physical phenomena. Whether we consider the interaction between two bubbles (drops) or between many (foams or emulsions), these interactions are complex and still poorly understood. An interesting case arises when two equal- and constant-volume bubbles (drops) interact with each other while being held by two axisymmetrically positioned frames of circular opening - a configuration which is frequently used in characterisation devices. The minimisation of the surface energy of this "double bubble" (or "double drop") configuration, constrained by the fixed volume and the frame boundaries, creates a complex landscape of shape spaces where physically stable shapes are separated by different types of instabilities. Combining experiments, finite element simulations and theory, we provide here for the first time a complete analysis of these shape spaces, considering the adhesive energy between the bubbles and the drops (expressed by the contact angle) as an additional control parameter. We provide the full shape diagrams for different contact angles (0°, 60° and 90°), including a detailed discussion of four types of instabilities. Two of these instabilities break the axisymmetry, while the two others break the connectivity of the ensemble. As far as we are aware, two of these instabilities have never been reported before. We accompany the shape and stability analysis with detailed mechanical characterisation using force and pressure measurements. Experiments, simulations and theory showing excellent agreement. This work will not only be useful in guiding the exploitation of double bubble (double drop) experiments on frames, but it also opens the possibility to exploit these configurations for the characterisation of increasingly complex bubble or drop interactions. Since the contact angle of 90° corresponds to an "imaginary" film separating the two bubbles (drops), our analysis naturally includes the shape and stability of a capillary bridge between two circular frames.

Bias Cuts and Data Dumps

Bias Cuts and Data Dumps

Object Detection for Aircraft Turnover Milestone based on Modified

In the target detection task of aircraft turnaround milestone in foggy scenario, there are some problems such as unstable location of prediction frame boundary, high error detection rate and poor detection effect of small target. A new target detection method BTM-YOLO (Broad-sighted upsample and three-dimensional attention multiple detection head YOLO) is proposed, which is based on YOLOv7 network. Add a small target detection head to improve the ability of small target detection; The up-sampling module OVRAFE is introduced to reduce the information loss in the up-sampling process. Replace CIoU with Median Wise IoU (MWIoU) to suppress the problem of poor sample swelling in data sets. The improved model makes up for the performance shortcomings of small target detection in foggy days, and the average detection accuracy on the real foggy day test set is 76.2%, which is 3.32% higher than that of the original model, basically meeting the task requirements.

Spatiotemporal directional coherence-based scrolling-text detection for frame rate up-conversion

This paper proposes a novel scrolling-text detection method that uses spatiotemporal directional coherence for frame rate up-conversion. Spatiotemporal directional coherence is defined as the coherence level of the spatiotemporal gradient distribution in consecutive frames. Existing scrolling-text detection methods usually detect text using the motion vectors of an image or the distributions of gradient components. The number of motion vectors to determine the scrolling-text decreases at the start and end points of the frame boundary. Therefore, they have difficulty accurately detecting the scrolling text from the start or end points of a frame boundary. The distributions of gradient components can be generated by non-scrolling-text components and they cannot consider the temporal information of consecutive frames, so they may erroneously detect non-scrolling-text regions as the scrolling-text. Unlike the previous methods, which are vulnerable to the presence of texture and noise, the core idea of the proposed method is to use the spatiotemporal directional coherence of the gradient components in the consecutive frames to detect the regions with a dominant edge orientation component for generation of the scrolling-text map and use bit codes from the luminance values to analyze the diversity of luminance patterns for refinement process. With these, the proposed method can further improve the detection accuracy compared to the benchmark methods. The experimental results showed that the proposed method enhanced the average F1 score by up to 0.5195 (a 137.69 % improvement) compared to the benchmark methods. The average computation time per pixel of the proposed method was also reduced by up to 16.205 μs (a 70.57 % reduction) compared to the benchmark methods.

Computing the area-minimizing surface by the Allen-Cahn equation with the fixed boundary

<abstract><p>The Allen-Cahn equation is a famous nonlinear reaction-diffusion equation used to study geometric motion and minimal hypersurfaces. This link has been scrutinized to construct minimal surfaces for many years. The shape of soap film is very interesting, and it can stimulate mathematical inspirations since it explains curvatures and equilibrium shapes in nature. There are many interesting ways to create area-minimizing surfaces with the boundaries, called frame boundaries. However, dealing with surface's ends (boundaries) numerically is not easy for constructing surfaces. This paper presents a mathematical formulation and numerical construction of area-minimizing surfaces, also known as minimal surfaces. We use differential geometry knowledge for numerical verification. The proposed numerical scheme involves fixed frame boundary conditions in the Laplacian operator. We treat the Laplacian with the constraint implicitly and explicitly solve the nonlinear free energy term. This approach ensures stable and efficient construction of area-minimizing surfaces with frame boundaries. In the numerical aspect, we suggest the construction of minimal surfaces by illustrating two classical examples, which are Scherk's minimal surface and catenoid. Both examples have the frame boundaries. Scherk's first surface is a doubly periodic, complete and properly embedded one with parallel ends. The catenoid is formed between two coaxial circular rings and is classified mathematically as the only properly embedded minimal surface with two ends and finite curvature. To be specific, we deal with two different frame boundaries, right angle frame and round frame boundaries, via two examples, Scherk's surface and catenoid.</p></abstract>

Toolpath generation for ultraprecision machining: Freeform surface generation and extrapolation

The rise in complexity of freeform optics drives the development of equally complex manufacturing processes needed to produce them. Complex optical designs, however, require equally complex machining toolpaths and techniques that can generate them. This paper and subsequent research develops and investigates toolpath generation techniques for explicitly defined surfaces of the form Z(X,Y). A generalized approach is developed for the toolpath generation of optical surfaces themselves as well as techniques for transitioning between surfaces in an array. All surfaces herein are continuous, well-behaved, and differentiable – constraints satisfied by most optical prescriptions today. The current paper describes the toolpath generation and extrapolation process for a tilted freeform surface defined inside a non-circular boundary. Boundaries are defined so that some non-convexity is acceptable, and it is simple to determine whether a toolpath coordinate lies inside or outside them. Using the proposed coordinate frame transformation and boundary definition, it is shown that by tilting a surface and boundary together, the tilted surface retains its original form and boundary in a rotated coordinate frame. With the proposed extrapolating surface, it is possible to modify a freeform surface outside its defined boundary so it is smooth and well-behaved inside its overall region of interest – an important consideration for both toolpath generation and opto-mechanical design. By combining freeform and extrapolating surfaces together, a smooth piecewise surface is generated whose overall continuity increases as the order of the extrapolating surface increases. As a result, it is possible to increase the overall continuity of a toolpath along its cutting direction. To verify the utility of the proposed extrapolating surface, experimental data are presented for several spiral toolpaths generated for a 6th order polynomial surface prescription defined inside a rectangular boundary. Subsequent research, using the techniques herein as a starting point, develop and investigate blending multiple freeform surfaces together.

Seismic analysis and connection optimization of the side column on modular prefabricated four‐sided connected composite shear wall

SummaryA modular prefabricated four‐side connected composite (MPFC) shear wall that consists of a composite shear wall modular (CSWM) and steel frame boundary elements is proposed. First, the finite element model (FEM) of the MPFC shear wall, which considers a plastic‐damage constitutive model of both concrete and steel materials, is established based on the finite‐element software ABAQUS. Second, the FEM accuracy of the MPFC shear wall is verified by the experimental results of a modular prefabricated two‐sided connected buckling‐restrained (MTB) steel plate shear wall. Third, the seismic performance of the MPFC shear wall is investigated based on the verified FEM. The connection between the CSWM and side column is optimized. Finally, the initial stiffness calculation formula of the MPFC shear wall that considers the impact of that the thickness ratio between the connection steel plate (CSP) and inner steel plate (ISP) is deduced. The results show that the peak bearing capacity, initial stiffness, total energy, and total strain energy of the MPFC shear wall increased by 42.47%, 44.81%, 113.24%, and 58.97%, respectively, compared with those of the MTB steel plate shear wall. The compressive corner damage of the reinforcement concrete faceplate (RCF) of the MPFC shear wall with a side column and CSWM is connected by a middle steel plate is effectively improved. Compared with those of the MPFC shear wall in which the side column and CSWM are connected by bolts, the shearing force, axial force, and bending moment of the side column of the MPFC shear wall in which the side column and CSWM are connected by the middle steel plate are notably decreased by 25.32%, 26.08%, and 39.51%, respectively. The FEM results are compared with the formula calculation results to establish its accuracy in calculating the initial stiffness of the MPFC shear wall.

Vibration analysis of laminated planar frame structures

A wave-based model is developed to analyze the free vibrations of symmetrically and asymmetrically laminated cross-ply planar frame structures. The model includes the effects of shear deformation, rotary inertia and the elastic coupling due to structural anisotropy. The frame is modeled as an assemblage of beam segments, whereby each segment acts as a one-dimensional waveguide. The system matrices governing wave propagation, reflection and transmission along the connected segments are derived. An advantage of the proposed model over numerical methods, such as the finite element method, is that exact solutions for the equations of motion are used to derive the system matrices of the frame. The matrices are subsequently assimilated to give a complete description of the wave train present during free vibration. The approach, which is well suited for implementation in conventional computing programs, can be used to determine the exact natural frequencies and mode shapes of the frame. By using the proposed model, the free vibration characteristics of inclined laminated portal frames are analyzed. The effects of stacking sequence, frame angle, relative frame length, orthotropicity ratios and boundary conditions on the exact natural frequencies, and in certain cases the mode shapes, are evaluated and discussed. The numerical results presented in this work are in close agreement with finite element (FE) simulations and where possible, published results.

Frame Boundary Detection and Deep Learning-Based Doppler Shift Estimation for FBMC/OQAM Communication System in Underwater Acoustic Channels

Underwater acoustic (UWA) communication is the only option for underwater long-distance wireless communication. However, its data rate is very low, in tens of kbps, and the time-varying nature of the UWA channel exhibits a Doppler effect. The data rate can be increased using a multicarrier technique, such as Filter Bank Multicarrier (FBMC). The FBMC-OQAM system does not require a cyclic prefix (CP) to eliminate intersymbol interference (ISI). Therefore, compared to other multicarrier techniques, the FBMC-OQAM system achieves the maximum spectral efficiency. Despite the well-designed filter, synchronisation errors cause performance degradation in the FBMC-OQAM system. In this paper, we propose frame boundary and Doppler frequency estimation methods for the FBMC-OQAM system under UWA channels. In this study, we propose a preamble-based frame boundary. The conjugate symmetry property is used in the frame boundary estimation. The performance of the proposed technique was studied under different UWA channels with different Doppler scale. The proposed time synchronisation technique yielded multiple peaks under UWA channels. A method for identifying the peak that represents the frame boundary is proposed. We compared the performance of proposed timing metric with existing three reference timing metrics. The proposed timing metric exhibited superior over two metrics and almost identical performance with the Liming’s metric with less computational complexity. In addition, we propose a convolutional neural network (CNN)-based Doppler scale estimation method. The proposed technique was shown to estimate a wide range of Doppler scale factors. The performance of the proposed technique was studied by considering different UWA channels at different SNRs. The proposed CNN architecture is analysed by changing the CNN parameters. Stacked autoencoders were adopted for Doppler scale estimation and the performance of the proposed CNN-based Doppler scale estimation method was compared with the stacked autoencoders based Doppler scale estimation method. Simulation results show that the proposed CNN-based Doppler Scale estimator exhibits good performance in UWA channels at different SNRs and Doppler scale factors.

The issues of meta-narrative structure in tom Stoppard’s play and film Rosencrantz and Guildenstern are dead

Tom Stoppards play and film Rosencrantz and Guildenstern Are Dead are analyzed in the article as metatexts at different levels of their semiotical and narratological structure. The specificity of dealing with dramaturgical praetextae of a film reinterpreted through a different semiotic system, in which sound, montage (film editing), frames and frame boundaries are significant, is presented. Particular attention is paid both to the theoretical grounding of metacinema as a genre and to the film analysis from the indicated viewpoint. The authors identify the manner in which both the play and the film reveal the core issue of the relationship between life and art, as well as provide their own analysis of the principles of interaction between the author, the text, and the reader. It is pointed out in the conclusions that the text of the cinema is structured as a complex cinematic game enjoying a multitude of semantic layers. Numerous oppositions such as fictional world vs. real world, traditionalism vs. the non-classical paradigm of aesthetics, etc. together with the use of a-text-within-a-text technique, allow to have the boundaries between theatre and cinematography outlined.

Automatic Real-Time Medical Mask Detection Using Deep Learning to Fight COVID-19

The COVID-19 pandemic is a virus that has disastrous effects on human lives globally; still spreading like wildfire causing huge losses to humanity and economies. There is a need to follow few constraints like social distancing norms, personal hygiene, and masking up to effectively control the virus spread. The proposal is to detect the face frame and confirm the faces are properly covered with masks. By applying the concepts of Deep learning, the results obtained for mask detection are found to be effective. The system is trained using 4500 images to accurately judge and justify its accuracy. The aim is to develop an algorithm to automatically detect a mask, but the approach does not facilitate the percentage of improper usage. Accuracy levels are as low as 50% if the mask is improperly covered and an alert is raised for improper placement. It can be used at traffic places and social gatherings for the prevention of virus transmission. It works by first locating the region of interest by creating a frame boundary, then facial points are picked up to detect and concentrate on specific features. The training on the input images is performed using different epochs until the artificial face mask detection dataset is created. The system is implemented using TensorFlow with OpenCV and Python using a Jupyter Notebook simulation environment. The training dataset used is collected from a set of diverse open-source datasets with filtered images available at Kaggle Medical Mask Dataset by Mikolaj Witkowski, Kera, and Prajna Bhandary. To simulate MobilNetV2 classifier is used to load and pre-process the image dataset for building a fully connected head. The objective is to assess the accuracy of the identification, measuring the efficiency and effectiveness of algorithms for precision, recall, and F1 score.

Some results about g-frames in Hilbert spaces

The concept of g-frame is a natural extension of the frame. This article mainly discusses the relationship between some special bounded linear operators and g-frames, and characterizes the properties of g-frames. In addition, according to the operator spectrum theory, the eigenvalues are introduced into the g-frame theory, and a new expression of the best frame boundary of the g-frame is given.

Multi-COBS: A Novel Algorithm for Byte Stuffing at High Throughput

Framing methods are used to break a data stream into packets in most digital communications. The use of a reserved symbol to denote the frame boundaries is a popular practice. This end-of-frame (EOF) marker should be removed from the packet content in a reversible manner. Many strategies, such as the bit and byte stuffing processes employed by high-level data link control (HDLC) and Point-to-Point Protocol (PPP), or the Consistent Overhead Byte Stuffing (COBS), have been devised to perform this goal. These bit and byte stuffing algorithms remove the reserved EOF marker from the packet payload and replace it with some extra information that can be used to undo the action later. The amount of data added is called <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">overhead</i> and is a figure-of-merit of such algorithms, together with the encoding and decoding speed. Multi-COBS, a new byte stuffing algorithm, is presented in this paper. Multi-COBS provides concurrent encoding and decoding, resulting in a performance improvement of factor four or eight in common word-based digital architectures while delivering an average and worst-case overhead equivalent to the state-of-the-art. On the reference 28-nanometer field programmable gate array (FPGA) (Artix-7), Multi-COBS achieves a throughput of 6.6 Gbps, instead of 1.7 Gbps of COBS. Thanks to its parallel elaboration capability, Multi-COBS is ideal for digital systems built in programmable logic as well as modern computers.

Rectangling irregular videos by optimal spatio-temporal warping

Image and video processing based on geometric principles typically changes the rectangular shape of video frames to an irregular shape. This paper presents a warping based approach for rectangling such irregular frame boundaries in space and time, i.e., making them rectangular again. To reduce geometric distortion in the rectangling process, we employ content-preserving deformation of a mesh grid with line structures as constraints to warp the frames. To conform to the original inter-frame motion, we keep feature trajectory distribution as constraints during motion compensation to ensure stability after warping the frames. Such spatially and temporally optimized warps enable the output of regular rectangular boundaries for the video frames with low geometric distortion and jitter. Our experiments demonstrate that our approach can generate plausible video rectangling results in a variety of applications.

Solving the boundary artifact for the enhanced deconvolution algorithm SUPPOSe applied to fluorescence microscopy

The SUPPOSe enhanced deconvolution algorithm relies in assuming that the image source can be described by an incoherent superposition of virtual point sources of equal intensity and finding the number and position of such virtual sources. In this work we describe the recent advances in the implementation of the method to gain resolution and remove artifacts due to the presence of fluorescent molecules close enough to the image frame boundary. The method was modified removing the invariant used before given by the product of the flux of the virtual sources times the number of virtual sources, and replacing it by a new invariant given by the total flux within the frame, thus allowing the location of virtual sources outside the frame but contributing to the signal inside the frame.

Using Fuzzy Inference System FIS for Identifying Motion in Digital Surveillance Systems

The aim of the current study is to use the FIS Fuzzy Inference System method to determine motion in digital surveillance systems. In the analysis, there are several methods used such as segmenting, sorting, evaluating and showing the results. After capturing an online video stream with an average of 1 frame/sec, the goal of the proposed method is to translate these frames to their corresponding representation of pixels and then use these frames as inputs for the job. The output is evaluated based on these inputs. The idea is to compare the average pixel representation of the current frame boundaries (column vectors) with the corresponding column vectors in the next frame, in order to find out whether there is any motion detected by comparing the average of the calculated column vector for the ith frame with the corresponding column vector in the i+1th frame. This operation leads to extracting 8 averages and it is considered as inputs to the fuzzy inference method. There is one output that will detect whether there is any motion detected or not. By designing a set of rules and then analyzing the results, a comparison of the averages is held.

Scientific Advice Considering “Science in Making”: The time frame and responsibility boundaries

Scientific Advice Considering “Science in Making”: The time frame and responsibility boundaries

ELM-Based Frame Synchronization in Nonlinear Distortion Scenario Using Superimposed Training

The requirement of high spectrum efficiency puts forward higher requirements on frame synchronization (FS) in wireless communication systems. Meanwhile, a large number of nonlinear devices or blocks will inevitably cause nonlinear distortion. To avoid the occupation of bandwidth resources and overcome the difficulty of nonlinear distortion, an extreme learning machine (ELM)-based network is introduced into the superimposed training-based FS with nonlinear distortion. Firstly, a preprocessing procedure is utilized to reap the features of synchronization metric (SM). Then, based on the rough features of SM, an ELM network is constructed to estimate the offset of frame boundary. The analysis and experiment results show that, compared with existing methods, the proposed method can improve the error probability of FS and bit error rate (BER) of symbol detection (SD). In addition, this improvement has its robustness against the impacts of parameter variations.

Model of Satellite Communication Channel Functioning under Conditions of Disturbances of Service Part of Frames by Unsteady Interference

The paper describes the main ways of organizing modern satellite communication systems and the methods of synchronization and transmission of service information used in them, the frame synchronization mechanism from the view point of noise immunity. Based on the analysis, a block diagram of a simulation model is proposed for studying the influence of unintentional interference on the channels of modern satellite communication systems. The proposed model of the impact of non-stationary interference on a satellite communication channel takes into account the effect of interference on symbolic, frame synchronization, mechanisms for extracting frame boundaries, as well as the effect of modern error correction codes. The model allows evaluating the impact of non-stationary interference on both the information and the service side of the frame of modern systems of broadband satellite communications. As an indicator of the noise immunity of a satellite communication channel, there was used probability of frame loss, i.e. frame skipping due to a violation in the frame synchronization system, incorrect allocation of frame boundaries, or the presence of errors in the frame that were not repaired by corrective codes. Using this model, we studied the effect of non-stationary interference of various durations on the information and service parts of the frame, compared the results of the impact of non-stationary interferences of various durations with the effect of white Gaussian noise. It is shown that non-stationary interference, which are short noise pulses that do not affect the information part of the frame due to reparation by correction codes, can significantly reduce the reception quality due to disruption of frame synchronization and distortion of service information about the signal-code structure and frame length.