Intermediate Plane Research Articles

One Stage Modified KOYANAGI-HAYASHI Technique with Tunica Vaginalis Intermediate Layer for Severe Hypospadias Surgery

Introduction: In recent years, the modified Koyanagi-Hayashi technique has attracted considerable interest due to its satisfactory results and low risk of major postoperative complications for the patient during surgery for severe hypospadias. The aim of this work is to evaluate this technique and compare our results with those of other research series. Materials and methods: A single-center prospective study of an inhomogeneous series of 32 children with proximal hypospadias and a mean age of 44 months was operated on by the same surgeon using the Koyanagi-Hayashi technique. Preoperative hormonal stimulation with testosterone was indicated in 17 children. The tunica vaginalis was used as the urethroplasty covering plane for all patients. Functional results were assessed, and a questionnaire was completed to evaluate the functional and aesthetic satisfaction of the parents and the surgeon. Results: Complete curvature of the penis was obtained in all patients except 2, who retained a minimal curvature, not requiring surgical correction at this time. There were 6 cases of urethral fistula, 2 cases of total urethroplasty release, 2 cases of partial release, 9 cases of glanduloplasty release, one urethrocele, and 2 meatus strictures. Overall, the success rate after the first procedure was 31.20%, rising to 74.95% after the first repeat procedure and 84.32% after the second. The result was very satisfactory for the parents at 84.37% and satisfactory at 15.62%. Conclusion: The Koyanagi technique modified by Hayashi is a good alternative for severe forms of hypospadias. Correction of the curvature of the penis is generally achieved without further procedures, and the aesthetic result is generally satisfactory. Using the tunica vaginalis as an intermediate plane to cover the urethroplasty has greatly reduced the rate of serious complications. The complication rate is high, and parents need to be aware of the risk of repeat surgeries. But these complications are always easy to manage

Off-axis reflective microscope objective with a centimeter scale field of view and micron resolution.

Microscope objectives with wide field-of-view (FOV) and high resolution are urgently needed for the frontier research in life sciences. However, traditional transmission microscope objectives typically have a narrow FOV and severe chromatic aberration. A new off-axis reflective microscope objective with a centimeter scale FOV and micron resolution is proposed in this paper. This objective, with its simple structure, can operate over a wide wavelength range. A design method for a wide FOV optical system is presented, which can eliminate the obstruction of the rays and control the intermediate image plane. Using this method, we design a novel off-axis four-mirror microscope objective with a FOV of 10 mm × 1.5 mm and a numerical aperture of 0.33.

V892 Tau: A tidally perturbed circumbinary disc in a triple stellar system

V892 Tau is a young binary star surrounded by a circumbinary disc that shows hints of an interaction with the low-mass nearby star V892 Tau NE. The goal of this paper is to constrain the orbit of V892 Tau NE and to determine the resulting circumbinary disc dynamics. We present new ALMA observations of the V892 Tau circumbinary disc at a twice higher angular and spectral resolution. We modelled the data with V892 Tau as a triple system and performed a grid of hydrodynamical simulations testing several orbits of the companion. The simulation outputs were then post-processed to build synthetic maps that we compared to the observations. The 12CO emission of the disc shows clear non-Keplerian features such as spiral arms. When comparing the data with our synthetic observations, we interpreted these features as ongoing interactions with the companion. Our simulations indicate that an eccentricity of $e of the companion is needed to reproduce the observed disc extent and that a mutual inclination of $ i with the inner binary reproduces the measured disc tilt. In order to explain most of the features of the circumbinary disc, we propose that V892 Tau NE follows an orbit with a mild eccentricity $0.2 < e < 0.5$ and a mutual inclination of $30 i < 60 Such a misaligned companion suggests the disc is oscillating and precessing with time, stabilising in an intermediate plane with a non-zero mutual inclination with the inner binary. Given the orbital configuration, we show that the stability of future planets is compromised in the second half of the disc once the gas has dissipated.

True triaxial unloading test on the mechanical behaviors of sandstone: Effects of the intermediate principal stress and structural plane

A series of true triaxial unloading tests are conducted on sandstone specimens with a single structural plane to investigate their mechanical behaviors and failure characteristics under different in situ stress states. The experimental results indicate that the dip angle of structural plane (θ) and the intermediate principal stress (σ2) have an important influence on the peak strength, cracking mode, and rockburst severity. The peak strength exhibits a first increase and then decrease as a function of σ2 for a constant θ. However, when σ2 is constant, the maximum peak strength is obtained at θ of 90°, and the minimum peak strength is obtained at θ of 30° or 45°. For the case of an inclined structural plane, the crack type at the tips of structural plane transforms from a mix of wing and anti-wing cracks to wing cracks with an increase in σ2, while the crack type around the tips of structural plane is always anti-wing cracks for the vertical structural plane, accompanied by a series of tensile cracks besides. The specimens with structural plane do not undergo slabbing failure regardless of θ, and always exhibit composite tensile-shear failure whatever the σ2 value is. With an increase in σ2 and θ, the intensity of the rockburst is consistent with the tendency of the peak strength. By analyzing the relationship between the cohesion (c), internal friction angle (φ), and θ in sandstone specimens, we incorporate θ into the true triaxial unloading strength criterion, and propose a modified linear Mogi-Coulomb criterion. Moreover, the crack propagation mechanism at the tips of structural plane, and closure degree of the structural plane under true triaxial unloading conditions are also discussed and summarized. This study provides theoretical guidance for stability assessment of surrounding rocks containing geological structures in deep complex stress environments.

Static friction testing of various materials in liquid nitrogen

The Deep Underground Neutrino Experiment will utilize charge readout planes (CRPs) that are submerged within liquid argon. These charge readout planes are part of a drift detector used measure the cascade of charged particles generated by the interaction of neutrinos with the argon nuclei. The CRPs require specially designed supports to ensure they remain precisely positioned even after the thermal contraction of the sensors and the cryostat that occurs during cooldown. These supports must also protect the cryostat floor and CRPs from potential damage due to thermal strain during cooldown. These objectives are satisfied by utilizing an intermediate slip plane within the support to provide a stress relief point with a lower friction coefficient than the interface between the sensor support and the cryostat floor. Therefore, the design of these supports requires knowledge of the static coefficient of friction for various materials at cryogenic temperatures. It was found that the coefficient of friction associated with materials such as metals, ceramics, and polymers have been studied very little at cryogenic temperatures. Specifically, there is not much data relative to the static coefficient of friction associated with polymers at low temperatures. Therefore, a test apparatus was developed to measure various materials’ cryogenic static coefficient of friction with the geometry required for the support design. Several tests with different materials were carried out using this test apparatus to identify a material combination with very different static coefficients of friction that can be used for the membrane to support interface and intermediate slip plane.

Band-amplified angle spectrum method for the phase hologram design to achieve high-quality holographic imaging in long distance

The angular spectrum method (ASM) is widely used in the design of computer-generated holograms (CGH) due to its strict adherence to the Helmholtz equations and the potential for accelerated computation using fast Fourier transform (FFT). However, when dealing with long distance propagation conditions, the reduction of effective spectral components and spectral aliasing will introduce significant computation errors, leading to a substantial degradation in holographic imaging quality. To achieve high-quality holographic imaging design in long distance, we introduce a novel angular spectrum computation method, the calculation process is divided into two steps: (1) First propagate a longer distance from the CGH plane to an intermediate plane. (2) Then continue to propagate to the observation plane after incorporating a spread spectrum phase factor to amplify the effective non-aliased bandwidth in the intermediate plane and eliminating the aliasing artifacts. Furthermore, the non-uniform fast Fourier transform (NUFFT) algorithm is adopted which allows for the flexible adjustments of the sampling interval and quantity in the spatial frequency domain, all while maintaining compliance with the Nyquist sampling theorem even in the context of bandwidth amplification. Both simulations and optical experiments are conducted to validate the feasibility and effectiveness of our proposed method.

Effect of forward kinematics on the motion-trajectory oscillations and inertia forces

In vehicle-motion scenarios, non-negligible centrifugal-force component that cannot be balanced by the gravity force may develop, leading to increase in wheel-contact forces. This inertia-force component, which depends on vehicle forward velocity and oscillation amplitude, can arise when the vehicle negotiates straight road or railroad track. An approach based on the Frenet geometry and recorded motion trajectory (RMT) is introduced in this investigation to examine forward-kinematics effect on the motion geometry and inertia forces and to obtain general expression of the ratio between the amplitudes of the centrifugal and gravity forces. While the two three-dimensional vectors of applied and constraint forces define Frenet osculating plane of mass-center trajectories; for non-centroidal points, the osculating plane is defined by two vectors; the resultant of the applied and constraint forces and an inertia-force vector that depends on the angular velocity and angular acceleration. The concepts of instantaneous motion plane (IMP) and instantaneous zero-force axis (IZFA) are used to convert three-dimensional Cartesian forces into two-dimensional Frenet forces, based on the Frenet-Newton equations. Because contact forces can be formulated using two fundamentally different approaches; constraint contact formulation (CCF) and elastic contact formulation (ECF), the effect of the contact formulation on the IMP and IZFA orientation is examined. The results obtained, using railroad suspended wheelset example, demonstrate the following: (1) limitations of roller rigs that do not properly account for forward-velocity effect on the inertia forces; (2) difference between IMP and intermediate wheelset plane defined by wheelset lateral axis and global vertical axis; (3) non-negligible inertia centrifugal-force component in the absence of physical curvature; and (4) need to distinguish between physical and motion geometries; the latter is one that directly enters into the definition of the inertia forces. Trajectories with oscillation frequency independent of the oscillation amplitude for a given forward velocity are also identified.

Alignment method of intermediate image plane imperfect imaging near-infrared catadioptric system

Alignment method of intermediate image plane imperfect imaging near-infrared catadioptric system

Dislocations in naturally deformed olivine: Example of a mylonitic peridotite

We have investigated the microstructure of naturally deformed olivine (chemically equilibrated at 1000 °C) by conventional transmission electron microscopy and electron tomography. The peridotite specimen, from Oman ophiolite, has a mylonitic microstructure with remnant, strongly deformed, millimetric porphyroclasts co-existing with small newly formed olivine grains generated by dynamic recrystallization. Imaging by transmission electron microscopy reveals that both newly formed grains and porphyroclasts display [100] and [001] dislocations activity. Subgrain boundaries are composed of either [100] or [001] dislocations. The characterization of this natural sample also permits to identify sporadic [100] dislocation loops, rare [010] dislocation, infrequent melt, and intragranular bubbles or along subgrain boundaries. Electron tomography permits to identify several glide planes, which are similar to previous observations acquired on experimentally deformed polycrystalline olivine, more importantly electron tomography also permits to evidence combination of glide, climb and mixed climb (dislocation moving in an intermediate plane between the plane of glide plane and the plane of pure climb). Our study further infers the diversity of linear defects responsible for plastic deformation of olivine at lithospheric conditions.

Investigation of stress states around a finite-height crack

This paper is concerned with the analysis of a crack that has a finite-height at its crack tip, loaded under Mode I and II loading. The stress field around the “crack-height” region has been analysed and local Williams’ eigensolutions collocated using the H-integral. Results of the analysis help us to predict which one of the three possible places that fracture failure could occur is most likely, i.e., (1) at the middle plane of the crack tip (collinear with the sharp crack problem), (2) at the “notch corner” or (3) at the intermediate plane between the notch corner and the middle plane (intermediate state). A practical example of an infinite plane with a rectangular shaped crack has also been shown to demonstrate the practical use of the results of this paper.

Analysis of Power Transfer Characteristics of IPT System With Near Field Magnetic Coupling

This article investigates the working principle of the inductive power transfer (IPT) system from the perspectives of electromagnetic field distribution. According to the limitations of frequency and transmission distance, it is proved in this paper that the IPT system works in the near field, where the energy density of the magnetic field is much stronger than that of the electric field. Therefore, only the magnetic field in the IPT system needs to be considered in approximate power analysis. The mutual inductance model of the IPT system is an approximate and simplified form of the electromagnetic field model. The complex form of the Poynting vector of the IPT system is integrated over an intermediate infinite plane of the two coils to reveal the power transfer characteristics including the active and reactive power. When the system is in full resonance, only active power is transferred without reactive power, which is consistent with the results obtained from the circuit model. This article is useful to provide an insight into the power flow and energy distribution of the IPT system.

Diffraction-based dual path multispectral imaging

Abstract Diffraction based multispectral imaging is a method for obtaining snapshot multispectral image information by using a structured diffraction grating or computer-generated hologram in an intermediate image plane of an imaging system. Without the need of complicated filter manufacturing it becomes possible to realize application specific spatio-spectral sampling of an image. The spectral resolution is coupled with the spatial resolution because the central stop of the imaging system serves also as the main spectral filtering component. By using two image sensors and the zeroth order of the computer-generated holograms it becomes possible to obtain high resolution spatial information as well as spectral information on a coarser sampling grid.

Design of a Large Field of View and Low-Distortion Off-Axis Optical System Based on a Free-Form Surface

Free-form surfaces have good aberration correction capability and balance capability for nonrotationally symmetric imaging systems. In this study, we analyzed the quantitative relationship between X–Y polynomial combination and aberration for the efficient design of X–Y free-form optical systems. The purpose of this study was to provide an exhaustive design method for off-axis triple inverse optical systems with X–Y free-form surfaces. Finally, we designed a free-form off-axis optical system with a large field of view (FOV) and low distortion based on the off-axis triple inverse optical system without an intermediate image plane. The primary mirror (PM) of the system adopted an X–Y polynomial free-form surface to correct the aberration of different FOVs of the system and improve the image width and quality. The optical system had a focal length of 1000 mm, an F-value of 9.5, an FOV angle of 23° × 1°, a maximum distortion grid in the FOV less than or equal to −0.05%, and a full-field average wave aberration better than 0.055 λ (λ/18.2, λ = 632.8 nm). The analysis of the design results showed that the system had high-quality imaging and a compact structure. This design method can provide a technical reference for the study of such free-form off-axis systems.

Frequency-domain compression imaging for extending the field of view of infrared thermometers.

We propose a computational imaging technique for expanding the field of view of infrared thermometers. The contradiction between the field of view and the focal length has always been a chief problem for researchers, especially in infrared optical systems. Large-area infrared detectors are expensive and technically arduous to be manufactured, which enormously limits the performance of the infrared optical system. On the other hand, the extensive use of infrared thermometers in COVID-19 has created a considerable demand for infrared optical systems. Therefore, improving the performance of infrared optical systems and increasing the utilization of infrared detectors is vital. This work proposes a multi-channel frequency-domain compression imaging method based on point spread function (PSF) engineering. Compared with conventional compressed sensing, the submitted method images once without an intermediate image plane. Furthermore, phase encoding is used without loss of illumination of the image surface. These facts can significantly reduce the volume of the optical system and improve the energy efficiency of the compressed imaging system. Therefore, its application in COVID-19 is of great value. We design a dual-channel frequency-domain compression imaging system to verify the proposed method's feasibility. Then, the wavefront coded PSF and optical transfer function (OTF) are used, and the two-step iterative shrinkage/thresholding (TWIST) algorithm is used to restore the image to get the final result. This compression imaging method provides a new idea for the large field of view monitoring systems, especially in infrared optical systems.

Three-dimensional numerical simulation of oxygen isotope transport in lanthanum strontium manganese - Yttria-stabilized zirconia cathode of solid oxide fuel cell

Distribution of oxygen isotope 18O concentration which was labeled in lanthanum strontium manganese (LSM) – yttria-stabilized zirconia (YSZ) cathode of a solid oxide fuel cell (SOFC) is predicted through numerical simulations using a three-dimensional microstructure which was reconstructed by a focused ion beam-scanning electron microscopy (FIB-SEM). The electrochemical reaction under the SOFC operation is first numerically simulated, then the unsteady 18O transport is simulated by coupling self-diffusion by concentration gradient, migration by the electrochemical potential field, and electrochemical reaction at the triple phase boundaries. Predicted results were compared with the measured 18O concentration by a secondary ion mass spectrometry taken at the intermediate plane of the reconstructed 3D microstructure, which showed qualitative consistency between them. Thus, from the direct correlation of the electrochemical reaction and 18O concentration in an actual electrode microstructure, influence of electrochemical reaction was discussed. The present approach provides useful information for the interpretation of the oxygen labeling experiment results, which can cultivate better understanding of the electrochemical reaction mechanism in the SOFC electrodes.

Co-linear common-path shearography with a zero-approaching shear amount and separate control of the spatial carrier for single-shot phase measurement.

A co-linear common-path shearography is proposed with spatial phase shift for single-shot phase measurement. The co-linear common-path configuration brings an enhanced robustness and stability of the measuring system, because the two laterally sheared interfering object waves propagate essentially along the same path, which cancels out the disturbance and noise in surroundings. Two functional features, which break through the limitations in conventional co-linear common-path shearography, are proposed and implemented, namely the zero-approaching shear amount and the separate control of the spatial carrier. Seldom shearography configured by co-linear common-path structure possesses with these two features, because the linearly aligned optics restricts the control parameters in regards to the shear amount and the spatial carrier. In the proposed scheme, an intermediate real image plane is created in the linearly aligned light path to address the issue of zero-approaching shear amount. A 4-f imaging system is embedded with an aperture in between to implement a separate control of the spatial carrier. The zero-approaching shear amount provides the sufficiently small shear to make sure the strain or slope field of complex deformation is resolvable. Meanwhile, the separate control of the spatial carrier further guarantees a well-distributed spatial frequency spectrum when the required zero-approaching shear amount is configured.

Analysis of photoplethysmogram signal to estimate heart rate during physical activity using fractional fourier transform – A sampling frequency independent and reference signal-less method

Background and objectiveAcquiring accurate and reliable health information using a PPG signal in wearable devices requires suppressing motion artifacts. This paper presents a method based on the Fractional Fourier transform (FrFT) to effectively suppress the motion artifacts in a Photoplethysmogram (PPG) signal for an accurate estimation of heart rate (HR). MethodsBy analyzing various PPG signals recorded under various physiological conditions and sampling frequencies, the proposed work determines an optimal value of the fractional order of the proposed FrFT. The proposed FrFT-based algorithm separates the motion artifacts component from the acquired PPG signal. Finally, the HR estimation accuracy during the strong motion artifact-affected windows is improved using a post-processing technique. The efficacy of the proposed method is evaluated by computing the root mean square error (RMSE). ResultsThe performance of the proposed algorithm is compared with methods in recent studies using test and training datasets from the IEEE Signal Processing Cup (SPC). The proposed method provides the mean absolute error of 1.88 beats per minute (BPM) on all twenty-three recordings. ConclusionsThe proposed method uses the Fourier method in the fractional domain. A noisy signal is rotated into an intermediate plane between the time and frequency domains to separate the signal from the noise. The algorithm incorporates FrFT analysis to suppress motion artifacts from PPG signals to estimate HR accurately. Further, a post-processing step is used to track the HR for accurate and reliable HR estimation. The proposed FrFT-based algorithm doesn't require additional reference accelerometers or hardware to estimate HR in real-time. The noise and signal separation is optimum for a fractional order (a) value in the vicinity of 0.6. The optimized value of fractional order is constant irrespective of the physical activity and sampling frequency.

Low polarization on-axis three-mirror reflective optical systems initial configuration designed by genetic algorithms

Low polarization systems have important advantages in many applications. Thanks to be with seven free design parameters, three-mirror reflective systems have good potential to achieve low polarization. A general method to design low polarization on-axis three-mirror systems is proposed in this paper. Based on genetic algorithms, the initial configurations of on-axis three-mirror systems with both low polarization aberrations and good wave aberrations can be found. In order to make the design results meet different requirements, various constraints are included in the merit functions, such as diattenuation, retardance, wave aberrations, structure size, intermediate image plane and flat focal plane. Different merit functions generate different optimal results. The method proposed in this paper is versatile and can be used to design other types of optical systems that demand low polarization.

Enlarging the FOV of lensless holographic retinal projection display with two-step Fresnel diffraction

The field of view (FOV) of holographic retinal projection display (RPD) is always restricted by the diffraction angle of a spatial light modulator (SLM). In this paper, we demonstrate a large FOV holographic RPD by using two-step Fresnel diffraction calculation. By adding the pupil plane as the intermediate plane and decreasing the sampling interval, the FOV can be enlarged to nearly two times of the diffraction angle limit without any physical change. Due to the added spherical wave phase, the influence of aliasing is eliminated because the adjacent orders are projected to different viewpoints. The nonuniform image intensity caused by the sinc function modulation is compensated by image pre-processing. Optical experiments verify that the proposed method can present a uniform holographic near-eye display with a large FOV and adjustable viewpoint position.

Synthetic aperture ptychography: coded sensor translation for joint spatial-Fourier bandwidth expansion

Conventional ptychography translates an object through a localized probe beam to widen the field of view in real space. Fourier ptychography translates the object spectrum through a pupil aperture to expand the Fourier bandwidth in reciprocal space. Here we report an imaging modality, termed synthetic aperture ptychography (SAP), to get the best of both techniques. In SAP, we illuminate a stationary object using an extended plane wave and translate a coded image sensor at the far field for data acquisition. The coded layer attached on the sensor modulates the object exit waves and serves as an effective ptychographic probe for phase retrieval. The sensor translation process in SAP synthesizes a large complex-valued wavefront at the intermediate aperture plane. By propagating this wavefront back to the object plane, we can widen the field of view in real space and expand the Fourier bandwidth in reciprocal space simultaneously. We validate the SAP approach with transmission targets and reflection silicon microchips. A 20-mm aperture was synthesized using a 5-mm sensor, achieving a fourfold gain in resolution and 16-fold gain in field of view for object recovery. In addition, the thin sample requirement in ptychography is no longer required in SAP. One can digitally propagate the recovered exit wave to any axial position for post-acquisition refocusing. The SAP scheme offers a solution for far-field sub-diffraction imaging without using lenses. It can be adopted in coherent diffraction imaging setups with radiation sources from visible light, extreme ultraviolet, and X-ray, to electron.