Orthogonal Patterns Research Articles

Chromatic aberration compensation in a digital camera lens for fringe projection profilometry

This work presents a simplified method for compensating the chromatic aberration of a digital camera lens using orthogonal fringe patterns displayed on an LCD monitor. The proposed compensation method drastically reduces the complex mathematical calculations to an arithmetic procedure of the simple rule of three. First, the implemented method is simulated, and then the experimental results confirm the simulated model. The mean squared error and standard deviation of the chromatic aberration compensation are calculated. Additionally, an arrangement is presented to avoid systematic errors when calculating the chromatic aberration of the lens to be compensated without additional digital processing.

3D reconstruction with single-frame two-step phase-shift method based on orthogonal composite fringe pattern projection

Abstract In order to realize single-frame three-dimensional (3D) reconstruction, a single-frame two-step phase-shift method based on orthogonal composite pattern projection is proposed to solve the problem that the traditional N-step phase-shift profilometry needs multiple projections for 3D reconstruction. The orthogonal composite pattern uses only two carrier channels to reduce the spectrum overlapping influence on the demodulation accuracy of carrier and modulated fringes. A two-dimensional variational mode decomposition method is adopted to remove the background DC component of the sinusoidal fringe to overcome the mode overlap problem by controlling the size of the bandwidth. Thus, the two-step phase-shift method is applied to calculate the phases for 3D reconstruction. The experimental results show that, compared with the typical Fourier transform profilometry method, 3-step composite method and 2 + 1 composite method, the 3D reconstruction accuracy of the proposed method is improved by 49.1%,31.4% and 23.2% respectively according to mean absolute error, and by 73.0%, 58.4% and 56.8% respectively according to mean squared error as the evaluation index. Finally, the dynamic 3D reconstruction experiment demonstrates the good adaptability of dynamic 3D reconstruction.

Dual-Band Antenna with Pattern and Polarization Diversity.

This study proposes a pattern-diversity antenna with different radiation patterns at two different frequency bands (f1 and f2; f1: broadside radiation pattern, f2: conical radiation pattern). The proposed structure consists of a central circular antenna and two annular ring antennas, with each of the antennas having individual ports. Two of the ports (port 1 and port 3) exhibit orthogonal broadside radiation patterns at low bands, and the other two ports (port 1 and port 2) exhibit orthogonal conical radiation patterns at high bands. Thus, they have polarization diversity characteristics. To improve isolation between the ports, the inner part of the annular ring antennas is shorted by an array, and the outermost port is positioned orthogonal to the other ports. Using this configuration, the isolation values between the ports are -26.7 and -30.1 dB at the two frequency bands, respectively. Using the fabricated prototype, experimental results show that the proposed antenna achieves -10 dB bandwidths of 240 MHz (5.71-5.95 GHz) and 210 MHz (7.69-7.9 GHz) at f1 and f2, respectively.

Abstract Mo105: End Systolic Pressure and Ejection Timing Correlate with Impaired Relaxation

Impaired relaxation is a common feature in most cases of diastolic dysfunction, including heart failure with preserved ejection fraction. Isovolumetric relaxation is typically characterized by τ, an exponential time constant, but may be broken into relaxation and stiffness-like parameters (µ and Ek). Recent in vitro work suggests that strain during late systole (protodiastolic period) modifies relaxation. We hypothesize that late systolic pressure and time indexes correlate with myocardial relaxation. Thirty-four (34) simultaneous aortic and left ventricular micromanometric (Millar) pressure traces were obtained from a comprehensive database of clinical cardiac catheterization patients. These patients underwent coronary artery disease screening and presented but did not have arterial blockages. Pressure and time parameters were calculated over a five-minute interval. Relaxation rate (1/τ), and stiffness (Ek) correlated to end systolic parameters in an orthogonal pattern to relaxation (µ). 1/τ showed strong correlations with time from peak pressure to aortic valve divided by ejection time (t54/t52, r = .675, p < .01) and moderate correlation to the pressure decline after peak pressure to aortic valve pressure divided by the pulse pressure (P45/P42, r = .577, p < .01). In parallel Ek showed moderate correlation with t54/t52 (r = .592, p < .01), and a moderate correlation with P45/P42 (r = .470, p < .01), the pressure at aortic valve closure (r = -.420, p < .05), and aortic augmentation index (AIx, r = -.360, p < .05). Finally, µ presented a moderate correlation to P45/P42 (r = .501, p < .05), the pressure at aortic valve closure (r = .404, p < .05), and AIx (r = -.357, p < .05). As predicted, ventricular relaxation in patients correlates with late systolic hemodynamics. Parameters or combinations of parameters may predict relaxation rates or correlate to in vivo late systolic strain. Prospective studies evaluating end systolic strain and relaxation merit consideration. Overall, these observations are consistent with in vitro studies that suggest that impaired cessation of contraction is a regulator of relaxation.

Gender Classification Using Viola Jones, Orthogonal Difference Local Binary Pattern and Principal Component Analysis

Facial recognition is currently a widely discussed topic, particularly in the context of gender classification. Facial recognition by computers is more complex and time-consuming compared to humans. There is ongoing research on facial feature extraction for gender classification. Geometry and texture features are effective for gender classification. This study aimed to combine these two features to improve the accuracy of gender classification. This research used the Viola-Jones and Orthogonal Difference Local Binary Pattern (OD-LBP) methods for feature extraction. The Viola-Jones algorithm faces issues in facial detection, leading to outliers in geometry features. At the same time, OD-LBP is a new descriptor capable of addressing pose, lighting, and expression variations. Therefore, this research attempts to utilize OD-LBP for gender classification. The dataset used was FERET, which contained various lighting variations, making OD-LBP suitable for addressing this challenge. Random Forest and Backpropagation were employed for classification. This research demonstrates that combining these two features is effective for gender classification using Backpropagation, achieving an accuracy of 93%. This confirms the superiority of the proposed method over single-feature extraction methods.

Insula uses overlapping codes for emotion in self and others.

In daily life, we must recognize others' emotions so we can respond appropriately. This ability may rely, at least in part, on neural responses similar to those associated with our own emotions. We hypothesized that the insula, a cortical region near the junction of the temporal, parietal, and frontal lobes, may play a key role in this process. We recorded local field potential (LFP) activity in human neurosurgical patients performing two tasks, one focused on identifying their own emotional response and one on identifying facial emotional responses in others. We found matching patterns of gamma- and high-gamma band activity for the two tasks in the insula. Three other regions (MTL, ACC, and OFC) clearly encoded both self- and other-emotions, but used orthogonal activity patterns to do so. These results support the hypothesis that the insula plays a particularly important role in mediating between experienced vs. observed emotions.

Direction-of-Arrival Estimation for Unmanned Aerial Vehicles and Aircraft Transponders Using a Multi-Mode Multi-Port Antenna.

Increasing airspace safety is an important challenge, both for unmanned aerial vehicles (UAVs) as well as manned aircraft. Future developments of collision avoidance systems are supposed to utilize information from multiple sensing systems. A compact sensing system could employ a multi-mode multi-port antenna (M 3PA). Their ability to radiate multiple orthogonal patterns simultaneously makes them suitable for communication applications as well as bearing and ranging applications. Furthermore, they can be designed to flexibly originate near-omnidirectional and/or directional radiation patterns. This option of flexibility with respect to the radiation characteristic is desired for antennas integrated in collision avoidance systems. Based on the aforementioned properties, M 3PAs represent a compelling option for aircraft transponders. In this paper, direction-of-arrival (DoA) estimation using an M 3PA designed for aerial applications is put to the test. First, a DoA estimation scheme suitable to be employed with M 3PAs is introduced. Next, the validity of the proposed method is confirmed through numerical simulations. Lastly, practical experiments are conducted in an antenna measurement chamber to verify the numerical results.

Printed Dual Band Antenna with Parasite Elements for LTE and 5G Applications

A printed antenna for long-term evolution (LTE) band (1.71–1.755 GHz) and 5G band (3.3–3.8 GHz) has been investigated in this article. A balanced feeder line is employed to feed the radiating element at the 5G band of operation, which becomes a radiator at the LTE band. The measured reflection coefficient (S11≤−10 dB) bandwidth is 6% (LTE band: 1.67–1.776 GHz) and 30.76% (5G band: 2.875–3.92 GHz). This antenna radiates with a gain of 3.25 dBi at the LTE band in the broadside and 6.5dBi at the 5G band in the end-fire direction. An open-ended tuning stub is used to tune out the reactance of the radiating element to enhance its radiation and act as a reflector to enhance the directivity in the 5G band. The printed parasite strip forces the beam towards the axial direction (end-fire) and enhances the gain in the 5G band. Both bands form an orthogonal radiation pattern. This antenna can also be utilized for WiMAX (3.5 GHz) band applications.

Metamaterial Inspired Varactor-Tuned Antenna with Frequency Reconfigurability and Pattern Diversity.

A metamaterial-inspired varactor-tuned antenna with frequency reconfigurability and pattern diversity is designed. Two different versions of a reconfigurable structure are integrated into a single antenna to excite two different orthogonal patterns, which realizes pattern diversity for MIMO applications. The outer annular Composite Right-/Left-Handed Transmission Line (CRLH-TL) works at the 1 mode and provides a broadside pattern, and the inner circular radiator loaded with split ring resonators (SRR) operates at the 0 mode and radiates an omnidirectional pattern, which realizes pattern diversity. By using surface-mounted varactors, the operating frequencies for the two radiation patterns can be tuned over a wide frequency range, from 1.7 GHz to 2.2 GHz, covering the 1.71-2.17 GHz LTE band, and a low mutual coupling between the two radiators is achieved. The antenna has also been prototyped. The measured results are in good agreement with the simulation results, verifying the proposed concept. The dual-mode MIMO system equipped with the proposed antenna elements is discussed within the context of a 3-D channel model, and it shows a superior array compactness and spectral efficiency (SE) performance compared to scenarios with single-mode elements.

Orthogonal Pattern Division Multiple Access Utilizing Optimal Frequency Hopping Patterns Constructed With Welch Costas Arrays

Orthogonal Pattern Division Multiple Access Utilizing Optimal Frequency Hopping Patterns Constructed With Welch Costas Arrays

Miniaturized circularly polarized metasurface antenna based on characteristic mode analysis

AbstractA miniaturized circularly polarized (CP) metasurface (MTS) antenna is investigated based on characteristic mode theory (CMT). The 4 × 4 square patch structure was used as the initial structure for characteristic mode analysis (CMA) and improvement using CMT to guide the evolution of antenna structures. The square ring is bent and the capacitive strips are introduced to obtain the final miniaturized MTS. Comparing the proposed MTS with traditional MTS, the proposed antenna size is significantly reduced. To give the proposed antenna a CP, a feeding structure with a 90° phase difference is designed to excite a pair of orthogonal target patterns. The final antenna structure has a reduced overall size and has circular polarization characteristics. For verification, the proposed CP MTS antenna is fabricated and measured. The measured results show an impedance bandwidth of 2.9–3.65 GHz and 3 dB axial ratio bandwidth of 3.1–3.57 GHz, and a stable gain in the operating frequency band.

Design of low-profile four-modes patterns metasurface antenna using characteristic mode analysis

In this paper, we propose a novel design approach for multi-mode antenna radiation patterns using characteristic mode (CM) theory. Specifically, we observe that the response of the multi-mode radiation pattern is a superposition of modal current responses, which can be controlled through port excitation. By combining the port excitations, we achieve the desired multi-mode radiation pattern. The feed structure can also be designed using CM theory. The validity of this intuition is confirmed through CM analysis. Subsequently, we use the proposed theory to design an antenna structure with a profile height of 0.07 λ0 (λ0 is the wavelength of the electromagnetic wave at 2.8 GHz in vacuum). This antenna is capable of achieving four orthogonal radiation patterns. Simulation and measurement of the antenna demonstrate that the four radiation patterns can operate simultaneously within a bandwidth of 17% (|S11|<−10 dB), with worst-case port isolation of −24 dB.

Orthogonal Pattern Louver Mixer for Two-Dimensional Air Mixing in HVAC Applications: Performance and Design Optimization

This article focuses on the investigation of the mixing and hydraulic performance of an orthogonal pattern louver mixer in a square duct. The investigation includes various configurations, including the following parameters: mixer spacing and louver pattern orientation for a pair of mixers, as well as louver angle and louver array size were for both a single and a pair of mixers. Additionally, operational parameters such as mixing length, total flow rate, and flow rate ratio between cold and warm air were considered. Experimental testing was conducted to assess the performance of the orthogonal pattern louver mixer across various parameter combinations. Additionally, a numerical model was developed to enhance understanding of the mixing pattern and flow behavior. Numerical results highlighted that the two-dimensional mixing flow, characterized by multiple vortices generated through the unique louver design, significantly contributed to rapid and robust mixing, effectively reducing maldistribution within a short mixing length. The performance of the orthogonal pattern louver mixer from the experimental results was compared to other mixer types, such as orifice type mixers and ASHRAE Standard 41.2-based “cheese grater” baseline louver mixers. The orthogonal pattern louver mixer was found to be outstanding, with a maximum mixing effectiveness of 88 % for a mixing length of 2.0 Dh. Although it caused a higher static pressure drop than the baseline louver mixers, it was still acceptable for industrial use. The findings indicate that the orthogonal pattern louver mixer is a promising option due to its simple design, easy fabrication, high mixing performance with low pressure drop, and two-dimensional mixing. The orthogonal pattern louver mixer was also less sensitive to flow rate and velocity maldistribution than orifice-type mixers. This article provides useful guidelines for designing and selecting the best mixer type for HVAC applications, considering factors such as cost-effectiveness, mixing performance, pressure drop, and sensitivity to flow rate and velocity maldistribution. In addition, the article offers valuable insights into the performance characteristics of single or dual-use orthogonal pattern louver mixers, as well as the importance of carefully selecting the louver angle and array size when configuring the mixer.

Texture characterization and classification of polarized images based on multi-angle orthogonal difference.

The Local Binary Pattern (LBP) and its variants are capable of extracting image texture and have been successfully applied to classification. However, LBP has not been used to extract and describe the texture of polarized images, and simple LBP cannot characterize the polarized texture information from different polarizations of angles. In order to solve these problems, we propose a new multi-angle orthogonal difference polarization image texture descriptor (MODP_ITD) by analyzing the relationship between the difference of orthogonal difference polarization images from different angles and the pixel intensity distribution in the local neighborhood of images from different angles. The MODP_ITD consists of three patterns: multi-angle polarization orthogonal difference local binary pattern (MODP_LBP), multi-angle polarization orthogonal difference local sampling point principal component sequence pattern (MODP_LPCSP) and multi-angle orthogonal difference polarization local difference binary pattern (MODP_LDBP). The MODP_LBP extracts local corresponding texture characteristics of polarized orthogonal difference images from multiple angles. The MODP_LPCSP sorts the principal component order of each angle orthogonal difference local sampling point. The MODP LDBP extracts the local difference characteristics between different angles by constructing a new polarized image. Then, the frequency histograms of MODP_LBP, MOD_LPCSP ,and MODP_LDBP are cascaded to generate MODP_ITD, so as to distinguish local neighborhoods. By using vertical and parallel polarization and unpolarized light active illumination, combined with the measurements at three different detection zenith angles, we constructed a polarization texture image database. A substantial number of experimental results on the self-built database show that our proposed MODP_ITD can represent the detailed information of polarization images texture. In addition, compared with the existing LBP methods, The MODP_ITD has a competitive advantage in classification accuracy.

Design and realization of directivity adjustable ring transducer

In this paper, a directional segmented ring transmitting transducer, which can radiate sound waves in any horizontal region, has been developed. First, we introduce the structure of the segmented ring transducer and the characteristics of its radiation sound field, investigate the transmitting beam pattern control method based on the modal synthesis, and propose orthogonal beam pattern functions to adjust steering angles. Then, the three-dimensional finite element model of the segmented ring transducer is established, and the amplitude and phase of sound pressure excited by the first three modes, respectively, are calculated as a function of the frequency. We can combine each mode to obtain the desired beam patterns, and simulate the transmitting beam patterns steering to different directions. Finally, we manufacture the segmented ring transducer and measure its transmitting directivity in an anechoic water tank, and the first three modes are also calibrated according to the measured sound pressure. The experimental results show that the beam pattern synthesized by the first two modes has a 3 dB down beam width of about 156◦ at 15 kHz after calibration, and the maximum source level is approximately 24 dB higher than the minimum. The −3 dB beam width synthesized by the first three modes is about 84◦ at 17 kHz after calibration. In addition, we also carry out the experimental test on the proposed beam control method, and the driving-voltage weighting vectors are designed to obtain good transmitting beam patterns steering to different angles.

Orthogonal ring patterns in the plane

We introduce orthogonal ring patterns consisting of pairs of concentric circles generalizing circle patterns. We show that orthogonal ring patterns are governed by the same equation as circle patterns. For every ring pattern there exists a one parameter family of patterns that interpolates between a circle pattern and its dual. We construct ring patterns analogues of the Doyle spiral, Erf and z^alpha functions. We also derive a variational principle and compute ring patterns based on Dirichlet and Neumann boundary conditions.

Full-optical photoacoustic imaging using speckle analysis and resolution enhancement by orthogonal pump patterns projection

This paper presents an approach for achieving full optical photoacoustic imaging with enhanced resolution utilizing speckle pattern analysis. The proposed technique involves projecting patterns derived from binary masks corresponding to orthogonal functions onto the target to elicit a photoacoustic signal. The resulting signal is then recorded using a high-speed camera and analyzed using correlation analysis of the speckle motion. Our results demonstrate the feasibility of this optical approach to achieve imaging with enhanced resolution without the need for physical contact with the target, opening up new possibilities for non-invasive medical imaging and other applications.

Improved active-tracking performance through Hadamard speckle contrast reduction.

We report wave-optics simulation results and benchtop experimental findings that demonstrate reduced centroiding error through a Hadamard speckle contrast reduction (HSCR). The method involves projecting multiple orthogonal phase patterns onto an actively imaged object within a single camera resolution cell and integration time. Ideally, performance improves in proportion to the square root of the number of such phase realizations applied. Using 16 subpixels per camera pixel, our simulated track performance consistently meets this expectation with a decent experimental agreement, particularly at smaller object sizes. This outcome has promising implications for active tracking and wavefront sensing, extending the utility of HSCR beyond its known benefits to coherent image quality.

Hexamethylene amiloride binds the SARS-CoV-2 envelope protein at the protein-lipid interface.

The SARS-CoV-2 envelope (E) protein forms a five-helix bundle in lipid bilayers whose cation-conducting activity is associated with the inflammatory response and respiratory distress symptoms of COVID-19. E channel activity is inhibited by the drug 5-(N,N-hexamethylene) amiloride (HMA). However, the binding site of HMA in E has not been determined. Here we use solid-state NMR to measure distances between HMA and the E transmembrane domain (ETM) in lipid bilayers. 13 C, 15 N-labeled HMA is combined with fluorinated or 13 C-labeled ETM. Conversely, fluorinated HMA is combined with 13 C, 15 N-labeled ETM. These orthogonal isotopic labeling patterns allow us to conduct dipolar recoupling NMR experiments to determine the HMA binding stoichiometry to ETM as well as HMA-protein distances. We find that HMA binds ETM with a stoichiometry of one drug per pentamer. Unexpectedly, the bound HMA is not centrally located within the channel pore, but lies on the lipid-facing surface in the middle of the TM domain. This result suggests that HMA may inhibit the E channel activity by interfering with the gating function of an aromatic network. These distance data are obtained under much lower drug concentrations than in previous chemical shift perturbation data, which showed the largest perturbation for N-terminal residues. This difference suggests that HMA has higher affinity for the protein-lipid interface than the channel pore. These results give insight into the inhibition mechanism of HMA for SARS-CoV-2 E.

The RNF220 domain nuclear factor Teyrha-Meyrha (Tey) regulates the migration and differentiation of specific visceral and somatic muscles in Drosophila.

Development of the visceral musculature of the Drosophila midgut encompasses a closely coordinated sequence of migration events of cells from the trunk and caudal visceral mesoderm that underlies the formation of the stereotypic orthogonal pattern of circular and longitudinal midgut muscles. Our study focuses on the last step of migration and morphogenesis of longitudinal visceral muscle precursors and shows that these multinucleated precursors utilize dynamic filopodial extensions to migrate in dorsal and ventral directions over the forming midgut tube. The establishment of maximal dorsoventral distances from one another, and anteroposterior alignments, lead to the equidistant coverage of the midgut with longitudinal muscle fibers. We identify Teyrha-Meyhra (Tey), a tissue-specific nuclear factor related to the RNF220 domain protein family, as a crucial regulator of this process of muscle migration and morphogenesis that is further required for proper differentiation of longitudinal visceral muscles. In addition, Tey is expressed in a single somatic muscle founder cell in each hemisegment, regulates the migration of this founder cell, and is required for proper pathfinding of its developing myotube to specific myotendinous attachment sites.