Orthogonal Characteristics Research Articles

Exploiting high-quality reconstruction image encryption strategy by optimized orthogonal compressive sensing

Compressive sensing is favored because it breaks through the constraints of Nyquist sampling law in signal reconstruction. However, the security defects of joint compression encryption and the problem of low quality of reconstructed image restoration need to be solved urgently. In view of this, this paper proposes a compressive sensing image encryption scheme based on optimized orthogonal measurement matrix. Utilizing a combination of DWT and OMP, along with chaos, the proposed scheme achieves high-security image encryption and superior quality in decryption reconstruction. Firstly, the orthogonal optimization method is used to improve the chaotic measurement matrix. Combined with Part Hadamard matrix, the measurement matrix with strong orthogonal characteristics is constructed by Kronecker product. Secondly, the original image is sparsely represented by DWT. Meanwhile, Arnold scrambling is used to disturb the correlation between its adjacent pixels. Following this, the image is compressed and measured in accordance with the principles of compressive sensing and obtain the intermediate image to be encrypted. Finally, the chaotic sequence generated based on 2D-LSCM is used to perform on odd-even interleaved diffusion and row-column permutation at bit-level to obtain the final ciphertext. The experimental results show that this scheme meets the cryptographic requirements of obfuscation, diffusion and avalanche effects, and also has a large key space, which is sufficient to resist brute-force cracking attacks. Based on the sparse and reconstruction algorithm of compressive sensing proposed in this paper, it has better image restoration quality than similar algorithms. Consequently, the compressive sensing image encryption scheme enhances both security and reconstruction quality, presenting promising applications in the evolving landscape of privacy protection for network big data.

Multilevel Regularization Method for Building Outlines Extracted from High-Resolution Remote Sensing Images

Extraction of vectorized building outlines from high-resolution remote sensing images is highly useful for various application fields, such as map creation and urban planning. However, this process is often complicated by external factors, such as trees and shadows, which cause issues, such as excessive node redundancy, jagged lines, and unclear corner points. In this study, a multilevel regularization method was designed for building outlines, including the “overall–local–detail” levels. First, overall regularization was performed by combining the minimum bounding rectangle of the building outline with the Hausdorff distance method. Next, based on the convex hull of the building outline and the distribution characteristics of nodes along the outline, the building outline was divided into multiple line chains and classified for local regularization. Finally, the details of the building outline were processed, with the parallel and perpendicular characteristics enhanced to obtain the final regularization results. The experimental results showed that the proposed method effectively enhances the edge representation accuracy of building outlines and significantly improves the accuracy and regularity of building edges. Furthermore, it strengthens the orthogonal characteristics of building outlines, providing more accurate representations of true building outlines.

A Novel MIMO Radar Orthogonal Waveform Design Algorithm Based on the Multi-Objective Improved Archimedes Optimization Algorithm

Realization and enhancement of detection techniques for multiple-input–multiple-output (MIMO) radar systems require polyphase code sequences with excellent orthogonality characteristics. Therefore, orthogonal waveform design is the key to realizing MIMO radar. Conventional orthogonal waveform design methods fail to ensure acceptable orthogonal characteristics by individually optimizing the autocorrelation sidelobe peak level and the cross-correlation sidelobe peak level. In this basis, the multi-objective Archimedes optimization algorithm (MOIAOA) is proposed for orthogonal waveform optimization while simultaneously minimizing the total autocorrelation sidelobe peak energy and total cross-correlation peak energy. A novel optimal individual selection method is proposed to select those individuals that best match the weight vectors and lead the evolution of these individuals to their respective neighborhoods. Then, new exploration and development phases are introduced to improve the algorithm’s ability to increase its convergence speed and accuracy. Subsequently, novel incentive functions are formulated based on distinct evolutionary phases, followed by the introduction of a novel environmental selection method aimed at comprehensively enhancing the algorithm’s convergence and distribution. Finally, a weight updating method based on the shape of the frontier surface is proposed to dynamically correct the shape of the overall frontier, further enhancing the overall distribution. The results of experiments on the orthogonal waveform design show that the multi-objective improved Archimedes optimization algorithm (MOIAOA) achieves superior orthogonality, yielding lower total autocorrelation sidelobe peak energy and total cross-correlation peak energy than three established methods.

Modeling and analysis of scattering in trifurcated guided waves with hard and flexible outer surfaces: A mathematical study

AbstractThis article discusses the scattering in a trifurcated guided wave featuring the combination of hard and flexible exterior surfaces. Through the formulation of the relevant boundary value problem and modes matching of orthogonal and non‐orthogonal functions, a comprehensive solution is obtained through infinite linear algebraic equations. The structural complexity of these structures introduces challenges related to non‐linearities in dispersive relations, and uncommon orthogonal characteristics of eigenfunctions. Therefore, by reorganizing the differential system into an algebraic one, a solution is obtained by truncating the system numerically. Further, analytical and numerical tests validate the solution, including graphical representations of relative powers versus frequency. The results reveal that transmission dominates reflection for frequencies above 900Hz in the symmetrical setting, with nearly equal power propagating through regions 2, 3, and 4. In the non‐symmetrical setting, power primarily transmits through region 4 for frequencies above 600Hz whereas most of the power being reflected at cut‐on frequencies when region 3 as rigid‐soft instead of rigid‐rigid. The obtained solution also confirms the properties of eigenfunctions, and the power distribution among different regions validates the accuracy of the solution. This work holds significance as it provides a standard procedure for modeling and solving a broad range of multifurcated problems with multiple dynamic boundary properties. The findings aid the understanding and development of waveguide systems, offering vision to practical applications in various fields involving complex wave propagation.

Acoustic radiation through a flexible shell in a bifurcated circular waveguide

The current study models and explains the fluid–structure coupled response of a flexible shell connected with two rigid coaxial shells via circular step discontinuities. Radiations from annular and inner regions of inlet rigid shells scatter on interfaces after interaction with the geometric variations and change of material properties. The flexible shell that supports vibrations along the shell is expressed though the Donnell–Mushtari formulation in the differential system. The mode‐matching technique is applied to solve the governing boundary value problem. The solution is projected on the orthogonal characteristics which in flexible casing is generalized as compared with the properties of acoustically rigid setting. The implication of generalized orthogonality relations governs additional constants that are found by defining the physical connection of shell with rigid disc. The clamped and pin‐jointed conditions are considered in this article. The scattering powers and transmission loss are analyzed against frequency, chamber length, and radii of shells for clamped and pin‐jointed edge conditions. It is found that the power propagation in annular shell and inner shell behave conversely. Moreover, configuration can be attenuated through the variation of dimensions of chamber and edge conditions.

Parameter Identification Method for a Periodic Time-Varying System Using a Block-Pulse Function

For periodic time-varying systems, a method of parameter identification based on the block-pulse function is presented. Firstly, the state-space equation of the system was expanded using the block-pulse function, then the recursion formula of the parameter identification of a time-varying system was obtained, according to the irrespective and orthogonal characteristics of the block-pulse function. This study provides a wide range of applications by saving time in calculation with a highly accurate method. The parameter identification was carried out by including the numerical simulation model of a three-degree freedom system and the vibration experiment results of an asymmetrical rotor system. The state space wavelet method and EMD method were compared cross-sectionally with the proposed method; this shows that the proposed method is accurate and effective, which makes it valuable in numerous applications. It also has a certain application value for several related projects.

Synchronous Vibration Moment Suppression for AMBs Rotor System in Control Moment Gyros Considering Rotor Dynamic Unbalance

In rotating machinery, the rotor mass unbalance will cause synchronous vibration, in which static unbalance will produce synchronous vibration force, and dynamic unbalance will produce synchronous vibration moment. In order to suppress the vibration moment of the magnetically suspended control moment gyro, a modified dual-channel notch filter (DNF) is proposed in this article. First, the modeling of the rotor system with mass unbalance is performed. Then, the design of modified DNF is carried out. This notch filter uses the equivalent vibration moment calculated by the current and displacement signals as input, and uses the orthogonal characteristics of the moment signals in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X</i> and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Y</i> directions to enter the controller at the same time. The stability of the rotor system with a DNF is proven. Finally, the experimental results are given to show that this method can effectively eliminate the synchronous vibration moment in the rotor system.

Diffraction deep neural network based orbital angular momentum mode recognition scheme in oceanic turbulence

Orbital angular momentum (OAM) has the characteristics of mutual orthogonality between modes, and has been applied to underwater wireless optical communication (UWOC) systems to increase the channel capacity. In this work, we propose a diffractive deep neural network (DDNN) based OAM mode recognition scheme, where the DDNN is trained to capture the features of the intensity distribution of the OAM modes and output the corresponding azimuthal indices and radial indices. The results show that the proposed scheme can recognize the azimuthal indices and radial indices of the OAM modes accurately and quickly. In addition, the proposed scheme can resist weak oceanic turbulence (OT), and exhibit excellent ability to recognize OAM modes in a strong OT environment. The DDNN-based OAM mode recognition scheme has potential applications in UWOC systems.

Generation of Higher-Order Hermite–Gaussian Modes via Cascaded Phase-Only Spatial Light Modulators

The spatial distribution of higher-order Hermite–Gaussian (HG) modes is more complicated than the fundamental mode, and the characteristics of different modes and their orthogonal characteristics have essential applications in the fields of measurement, imaging, and large-capacity communications. The main issue in future applications is how to efficiently generate higher-order HG modes. The spatial light modulator has high spatial resolution and excellent maneuverability, so it is a simple and effective way to generate higher-order HG modes. Here, the efficient generation of higher-order HG modes via cascaded spatial light modulators was experimentally investigated. For the HG90 mode, the conversion efficiency is 61%. The method with high conversion efficiency has promising application potentials in biophotonics, laser physics, and quantum information.

Experimental and numerical study on the low-velocity impact response of thermoplastic composite corrugated sandwich panels

Composite corrugated sandwich structures have a wide range of applications in aerospace field, and the loss of structural load carrying capacity due to low-velocity impact damage has become one of the main threats in practical applications. In this study, the impact resistance of corrugated sandwich panels prepared from thermoplastic composites (TPC) under low-velocity impact loading was investigated. Through a series of drop-weight experiments and finite element simulations, the impact response process and damage morphology of the thermoplastic composite sandwich panels were obtained, and the effects of different impact energy and different core arrangements on the energy absorption performance of the structure were explored. Finally, a parametric analysis of the perpendicularly-arranged double-layered corrugated sandwich panel was carried out. The results show that thermoplastic composite sandwich panels exhibit an overall collapse response rather than localised damage, and the structure maintains good integrity and stability. The perpendicularly-arranged sandwich panels rely on the orthogonal configuration characteristics to provide optimum impact load carrying capacity, their impact resistance can be further improved by increasing the thickness of top face-sheet and reducing the thickness of the middle face-sheet at the same time. This provides a basis for promoting the application of TPC in engineering and the design of sandwich structures.

Harmonic Vibration Control of MSCMG Based on Multisynchronous Rotating Frame Transformation

Magnetically suspended control moment gyro (MSCMG) is used in high-performance satellite platforms such as ultraquiet and ultrastable satellite. However, due to the unbalanced mass and sensor runout, the harmonic vibrations of synchronous and multifrequency will be generated, which will affect satellite performance. Aiming at the problem of harmonic vibration suppression of MSCMG, this article proposes a control algorithm based on multisynchronous rotating frame transformation. The electromagnetic force of the active magnetic bearing in MSCMG is directly used as the input signal of the control algorithm to achieve zero magnetic force control. This algorithm uses the orthogonal characteristics of the output signals of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X</i> -direction and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Y</i> -direction displacement sensors. The vibration force in both directions can be suppressed by one controller simultaneously, saving the computing resources and having a faster response speed. The stability of the proposed method and the robustness to frequency fluctuations are analyzed. By changing the phase compensation angle in different frequency ranges, the stability of the system in the whole frequency band is ensured. Finally, experimental results are given to verify that the proposed method can achieve high precision and fast response suppression of harmonic vibration.

New flexible deterministic compressive measurement matrix based on finite Galois field

Nowadays, the deterministic construction of sensing matrices is a hot topic in compressed sensing. The coherence of the measurement matrix is an important research area in the design of deterministic compressed sensing. To solve this problem, this paper proposes a novel sparse deterministic measurement matrix, which basically accesses the optimal low coherence of the measurement matrix. Firstly, a class of sparse square matrix is constructed based on finite fields' arithmetic. Then, the Hadamard matrix, or (discrete Fourier transform) DFT matrix, is nestled into the square matrix to construct an asymptotically optimal deterministic measurement matrix. That is, the relevant column vectors have orthogonal characteristics. Using this feature, the measurement matrix can be further optimized to reduce its mutual coherence, almost achieving the lower bound of the coherence (Welch bound). The two types of deterministic measurement matrices proposed are sparse with low mutual coherence and flexible measurement sizes. So, the proposed deterministic measurement matrices require less memory and time for the recovery as well as reducing the complexity due to their sparse structure. The simulation results show that compared with the existing (several typical) random matrices, the proposed method can reduce the mutual coherence and computational complexity of the measurement matrix.

Improving handover competency in preclinical medical and health professions students: establishing the reliability and construct validity of an assessment instrument

BackgroundAs part of the worldwide call to enhance the safety of patient handovers of care, the Association of American Medical Colleges (AAMC) requires that all graduating students “give or receive a patient handover to transition care responsibly” as one of its Core Entrustable Professional Activities (EPAs) for Entering Residency. Students therefore require educational activities that build the necessary teamwork skills to perform structured handovers. To date, a reliable instrument designed to assess teamwork competencies, like structured communication, throughout their preclinical and clinical years does not exist.MethodOur team developed an assessment instrument that evaluates both the use of structured communication and two additional teamwork competencies necessary to perform safe patient handovers. This instrument was utilized to assess 192 handovers that were recorded from a sample of 229 preclinical medical students and 25 health professions students who participated in a virtual course on safe patient handovers. Five raters were trained on utilization of the assessment instrument, and consensus was established. Each handover was reviewed independently by two separate raters.ResultsThe raters achieved 72.22 % agreement across items in the reviewed handovers. Krippendorff’s alpha coefficient to assess inter-rater reliability was 0.6245, indicating substantial agreement among the raters. A confirmatory factor analysis (CFA) demonstrated the orthogonal characteristics of items in this instrument with rotated item loadings onto three distinct factors providing preliminary evidence of construct validity.ConclusionsWe present an assessment instrument with substantial reliability and preliminary evidence of construct validity designed to evaluate both use of structured handover format as well as two team competencies necessary for safe patient handovers. Our assessment instrument can be used by educators to evaluate learners’ handoff performance as early as their preclinical years and is broadly applicable in the clinical context in which it is utilized. In the journey to optimize safe patient care through improved teamwork during handovers, our instrument achieves a critical step in the process of developing a validated assessment instrument to evaluate learners as they seek to accomplish this goal.

Simulation of J-Solution Solving Process of Navier–Stokes Equation

To avoid grid degradation, the numerical analysis of the j-solution of the Navier–Stokes equation has been studied. The Navier–Stokes equations describe the motion of viscous fluid substances. On the basis of the advantages and disadvantages of the Navier–Stokes equations, the incompressible terms and the nonlinear terms are separated, and the original boundary conditions satisfying the j-solution of the Navier–Stokes equation are analyzed. Secondly, the development of a computational grid has been introduced; the turbulence model has also been described. The fluid form and the initial value of the j-solution of the Navier–Stokes equation are combined. The original boundary conditions are solved by a computer, and the nonlinear turbulence equations are derived, which control the fluid flow. The simulation of the fine grid is comprehended to analyze the research outcome. Simulation analysis is carried out to generate multiblock-structured grids with high quality. The j-solution on the grid points is the j-solution that can be used with a fewer number of meshes under the same conditions. The proposed work is easy to implement, and it consumes lesser memory. The results obtained are able to avoid mesh degradation skillfully, and the generated mesh exhibits the characteristics of smoothness, orthogonality, and controllability, which eventually improves the calculation accuracy.

Solvent mixture formulation for orthogonal inkjet processing and uniform pixel patterning of quantum dot light-emitting diode

Quantum dot light-emitting diode (QLED) can be directly patterned for pixel array by solution processing, while the limitation of resolution and device stability exists unless a proper solvent system and multilayer design are established. With a small-sized nozzle inkjet printing process, solvent formulation effects on the morphology and precision of printing for the quantum dot layer were investigated. Drop formation as well as ink spreading and wetting behavior on the non-crosslinked organic hole-transporting polymer were optimized with a non-erosive solvent formulation composed of octane and cyclohexane. While the ink composition formed low-contact angle droplet on the surface and was not completely ideal for the defectless pixelating process of high-resolution inkjet, its controllability of wetting at a small-scale nozzle, uniform drying, and orthogonal characteristics with an effective hole transport layer resulted in a high-performance green inkjet QLED with 6.13 cd/A at 19,550 nits highly bright region. This amounted to about 50% of efficiency performance compared to an identical device prepared with spin-coating, but one of the best green inkjet QLED properties reported with less than 120-μm sub-pixel pitch.

A Modified Algorithm to identify the strongest velocity pulse in three orthogonal components of ground motions

An algorithm for the identification of the strongest velocity pulse is proposed based on wavelet analysis, which considers three orthogonal components of the ground motion. According to the NGA-West2 database, 6288 strong motion records were analyzed, and further, the classification results were compared with those obtained from the existing identification method of Shahi and Baker (2014) [1]. Among the results, our algorithm classified more records as pulse-like ground motion and has expanded the pulse identifications. In other words, the proposed algorithm can reflect the three orthogonal characteristics of the original ground motion records. Besides, the relationships of pulse amplitude, period with magnitude and fault distance were analyzed. Based on the analysis of near-fault ground motions containing velocity pulses, the following conclusions can be made: (1) The peak of the strongest velocity pulse gradually reduces with the increase of the fault distance, while gradually rises with the increase of the magnitude. Comparing with the fault normal or fault parallel orientation component, the strongest velocity pulse component has larger energy and smaller peak velocity. (2) For the relationship between the velocity pulse period and magnitude, results show that when Mw < 7, the predicted value of our model is larger than that of the Shahi and Baker (2014) [1] model; however when Mw ≥ 7, the prediction results from these two models are fairly close. The difference between the two models decreases as magnitude increases. That is because the strongest velocity pulses occupied more in the horizontal direction under a large magnitude.

Adaptive Orthogonal Characteristics of Bio-Inspired Neural Networks

Abstract In recent years, neural networks have attracted much attention in the machine learning and the deep learning technologies. Bio-inspired functions and intelligence are also expected to process efficiently and improve existing technologies. In the visual pathway, the prominent features consist of nonlinear characteristics of squaring and rectification functions observed in the retinal and visual cortex networks, respectively. Further, adaptation is an important feature to activate the biological systems, efficiently. Recently, to overcome short-comings of the deep learning techniques, orthogonality for the weights in the networks has been developed for the signal propagation and the efficient optimization of the learning. In this paper, bio-inspired asymmetric networks with nonlinear characteristics are proposed, which are derived from the retinal networks in the biological visual pathway. The asymmetric network proposed here was verified to detect the movement of the object, efficiently in our previous studies. This paper shows a new characteristic of the adaptive orthogonality in the asymmetric networks. First, it is shown that the asymmetric network with nonlinear characteristics is effective for generating orthogonality. Second, the proposed asymmetric network with Gabor filters is compared with the conventional energy model from the point of the orthogonality characteristics. Finally, the asymmetric networks with nonlinear characteristics can generate the extended orthogonal bases in independent subspaces, which are useful for classification and efficient learning.

The traveling wave formulation of a splitting chamber containing reactive components

The present work investigates the traveling wave formulation and their scattering characteristics in a waveguide having splitting expansion chamber. The segments of the chamber contain sandwiched elastic components backed by rigid cavities and absorbent linings. The structure is radiated by a plane wave mode incident which scatter on interaction with the expansion chamber. The mode-matching (MM) solution is developed to investigate the attenuation of fluid–structure coupled/uncoupled waves with reference to the properties of elastic components and absorbent material. The eigenmodes of segments comprising elastic components are non-orthogonal, and use of generalized orthogonal characteristics yields the convergent solution. The MM solution is validated altogether through apposite mathematical and physical arguments. Moreover, in low-frequency regime, the MM results are compared with low-frequency approximation, and a good agreement is found. Furthermore, it is observed that the characteristics of elastic components and the properties of absorbent material significantly affect the transmission loss, absorbing power and scattering energies.

Implementation of Orthogonal Codes Using MZI

Background: In Code Division Multiple Access (CDMA)/Multi-Carrier CDMA (MCCDMA), Walsh-Hadamard codes are widely used for its orthogonal characteristics, and hence, it leads to good contextual connection property. These orthogonal codes are important because of their various significant applications. Objective: To use the Mach–Zehnder Interferometer (MZI) for all-optical Walsh-Hadamard codes is implemented in this present paper. Method: The Mach–Zehnder Interferometer (MZI) is considered for the Tree architecture of Semiconductor Optical Amplifier (SOA). The second-ordered Hadamard and the inverse Hadamard matrix are constructed using SOA-MZIs. Higher-order Hadamard matrix (H4) formed by the process of Kronecker product with lower-order Hadamard matrix (H2) is also analyzed and constructed. Results: To experimentally get the result from these schemes, some design issues e,g Time delay, nonlinear phase modulation, extinction ratio, and synchronization of signals are the important issues. Lasers of wavelength 1552 nm and 1534 nm can be used as input and control signals, respectively. As the whole system is digital, intensity losses due to couplers in the interconnecting stage may not create many problems in producing the desired optical bits at the output. The simulation results were obtained by Matlab-9. Here, Hadamard H2 (2×2) matrix output beam intensity (I ≈ 108 w.m-2) for different values of inputs. Conclusion: Implementation of Walsh-Hadamard codes using MZI is explored in this paper, and experimental results show the better performance of the proposed scheme compared to recently reported methods using electronic circuits regarding the issues of versatility, reconfigurability, and compactness. The design can be used and extended for diverse applications for which Walsh-Hadamard codes are required.

Attenuation analysis of flexural modes with absorbent lined flanges and different edge conditions.

The analysis of fluid-structure coupled waveforms and the attenuation of these waveforms in a flexible waveguide is carried out. The physical configuration contains an expansion chamber connected by an extended inlet/outlet by means of vertical lined flanges. The governing boundary value problem is solved by using Mode-Matching (MM) technique. The associated eigen expansions of field potentials include non-orthogonal eigenfunctions and the related eigen-sub-systems are classified in the non-Sturm Liouville category, whereby the use of generalized orthogonal characteristics has ensured the point-wise convergence of solution. The low frequency approximation (LFA) which relies on the limited propagating modes is developed and is compared with MM solution. In the low frequency regime, a good agreement between MM and LFA results is found. Furthermore, the numerical experiments are performed to analyze the effects of absorbent linings and edge conditions on the attenuation of flexural modes. The guiding structure is exited with the structure-borne mode incident as well as the fluid-borne mode incident. It is found that the use of edge conditions and the absorbent linings significantly affect the attenuation of structure-borne mode and fluid-borne mode, respectively.