3D Mode Research Articles

Big LIDAR Data in Digital Earth: Ways Out of Dead End

During past 25 years, laser scanning has evolved from an experimental method into a fully autonomous family of Earth remote sensing methods. Now this group of methods provides the most accurate and detailed spatial data sets, while the cost of data is constantly falling, the number of measuring instruments (laser scanners) is constantly growing. The volumes of data that will be obtained during the surveys in the coming decades will allow the creation of the first sub-global coverage of the planet. However, the flip side of high accuracy and detail is the need to store fantastically large volumes of three-dimensional data without loss of accuracy. At the same time, the ability to work with the specified data in both 2D and 3D mode should be improved. Standard storage methods (file method, geodatabases, archiving, etc) solve the problem only partially. At the same time, there are some other alternative methods that can remove current restrictions and lead to the emergence of more flexible and functional spatial data infrastructures. One of the most flexible and promising ways of laser data storage and processing are quadtree and octree-based approaches. Of course, these approaches are more complicated than typical file data structures, that are commonly used for LIDAR data storage, but they allow users to solve some typical negative features of point datasets (processing speed, non-topological spatial structure, limited precision, etc.).

Influence of instability modes on cooling performance in hypersonic boundary layer with slot injection

A combined numerical-experimental investigation is presented with focus on the effects of boundary-layer instabilities and transition on the wall cooling performance in a Mach 5 low-enthalpy flow over a flat plate, with coolant injection achieved through a row of slots. The numerical study has been performed through direct numerical simulation (DNS) of the compressible Navier-Stokes equations, and is supported by results from linear stability analysis (LST) for the considered boundary layer. The experiments have been conducted in the High Density Tunnel (HDT) of the Oxford Thermofluids Institute, and include several blowing ratio conditions of injected air for the same freestream conditions. Surface heat transfer and pressure measurements, film effectiveness measurements, and Schlieren images are presented. The analysis links the wall cooling performance to the growth of imposed unstable boundary layer modes. Results indicate that 2D and 3D unstable modes, pertaining to the class of first instability modes, exist in the laminar boundary layer, and that imposition of these modes at different amplitudes leads to different states of the boundary layer, which we refer to as a perturbed state and a transitional state for medium and high amplitude respectively. As confirmed by comparison with experimental data, the perturbed and transitional states of the boundary layer significantly affect the wall cooling performance, providing an increase of the wall heat flux that results in a reduction of the beneficial effects of cooling.

MRI and CT venography in the diagnosis of hemodynamic disorders in patients suffering from the lower extremities veins chronic diseases Part I. Possibilities of MRI in visualization of the vascular blood flow of the lower extremities

Despite the fact that most vascular surgeons in Russia rarely use magnetic resonance imaging (MRI) in their daily practice, today interest in this method of imaging among specialists in the world is steadily increasing. This is due to the desire of clinicians to have another non – invasive method for diagnosing hemodynamic disorders of both the arterial (Magnetic Resonance Angiography – MRA) and venous vascular bed (Magnetic Resonance Venography – VRA). The development of these methods today is associated with the solution of many technical problems, the development of special pulse sequences and post-processing methods for the resulting image. This literature review analyzes published scientific data on the methodology of MRI in relation to the vascular system and the choice of optimal scanning modes. Taking into consideration the fact that this material is intended primarily for vascular surgeons and phlebologists, and not radiologists, the first part summarizes the basic understanding of the physical phenomena underlying the MRI image, without which a thoughtful analysis of the advantages and disadvantages of MR-Angiography and the search for the most optimal scanning mode for MR-Venography is not possible. Based on the constant desire of clinicians to be self-educated, it seems that this part of the presented material will not be difficult to understand. When describing the developed contrast-free and contrast-free MRA methods, attention is paid to the traditional methods of image processing in 2D mode (TOF, PC) using pulse sequences: spin echo (SE), multi-echo (SE T2), turbo spin echo (TSE), fast Advanced Spin Echo (fast Advanced Spin Echo-FASE), gradient echo (Gradient Echo-GE, GRE) and inversion recovery (Inversion Recovery-IR). In addition, the focus is on the most modern solu tions, including: multiplantar reformatting (MPR), maximum intensity projection (MIP), subvolume maximum intensity, surface rendering (SR), volume rendering (VR) and virtual intraluminal endoscopy (VIE). For all the methods used today, MR-Angiography is shown to be specific and informative, with a detailed analysis of the advantages and disadvantages. The nuances of understanding the resulting angiographic image in T1 and T2-weighted images and the phenomena of “bright blood” and “black blood” are shown. Since the absence of information or a brief mention only about the possibilities of using MRI in the diagnosis of hemodynamic disorders in patients with vascular pathology in Russian scientific literature it seems that this material is relevant and will arouse some interest from various specialists. Of particular interest is the potential use of contrast-free and contrast – free MR Angiography in the study of venous pathology of the lower extremities and pelvis, especially with regard to timely and accurate diagnosis of deep venous thrombosis (deep Vein Thrombosis-DVT) and venous thromboembolism (Venous Thrombosis – Embolism – VTE), which occupy a special position in the structure of patients with chronic venous Disorders of the lower extremities (Chronic Venous Disorders-CVD).

Cold-Test of Transverse Input-Output Microwave Circuit Components for a High-Power W-Band Gyro-TWT

The input/output microwave circuit of a W-band gyrotron traveling-wave tube (gyro-TWT) with a predicted output pulse power of more than 300 kW and a bandwidth of about 8% is under investigation. A distinctive feature of this circuit is the transverse (relative to the axial velocity of the electrons in the gyro-TWT) extraction of the output power and its compatibility for feeding and coupling the microwaves out through one oversized barrier window. The whole circuit consists of components inside and outside the tube vacuum volume. The key elements of the inner circuit are a waveguide mode converter forming the ring-like distribution of the radiation from the incoming TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1,1</sub> mode and a 45° inclined mirror with a hole enabling a lossless transport of the gyro-TWT electron beam to the collector. Aluminum prototypes of these components have been fabricated and cold-tested in the frequency range of 90-102 GHz. The measured 2D mode patterns and level of the cross-polarization are found to be in good agreement with the simulations.

A new form of liquid matter: Quantum droplets

This brief review summarizes recent theoretical and experimental results which predict and establish the existence of quantum droplets (QDs), i.e., robust two- and three-dimensional (2D and 3D) self-trapped states in Bose-Einstein condensates (BECs), which are stabilized by effective self-repulsion induced by quantum fluctuations around the mean-field (MF) states [alias the Lee-Huang-Yang (LHY) effect]. The basic models are presented, taking special care of the dimension crossover, 2D → 3D. Recently reported experimental results, which exhibit stable 3D and quasi-2D QDs in binary BECs, with the inter-component attraction slightly exceeding the MF self-repulsion in each component, and in single-component condensates of atoms carrying permanent magnetic moments, are presented in some detail. The summary of theoretical results is focused, chiefly, on 3D and quasi-2D QDs with embedded vorticity, as the possibility to stabilize such states is a remarkable prediction. Stable vortex states are presented both for QDs in free space, and for singular but physically relevant 2D modes pulled to the center by the inverse-square potential, with the quantum collapse suppressed by the LHY effect.

Understanding the 3D Formation of a Wide Rift: The Central South China Sea Rift System

AbstractRifted margins result from continental lithosphere extension, breakup, and transition to seafloor spreading by modes typically described by end‐member conceptual models. However, current geophysical data challenge these archetypes showing a more complex spectrum of rifting styles. Here, we integrate geophysical and geological observations to constrain the time and space evolution of the central South China Sea (SCS) rift system. We provide new insights into the continental extension mechanisms and continent‐ocean transition (COT) formation from a seismic transect parallel to the extensional direction of the central SCS rift system. We present 850‐km‐wide region of continental crust where distributed extensional deformation formed a pattern of lithospheric boudinage defined by seven 100‐ to 200‐km‐long structural segments. Each segment is formed by an 18‐ to 24‐km‐thick crust sector laterally thinning into an interboudin neck with ≤10‐km ultrathin crust (ß factors ~3.3–6.5). Drill and stratigraphic information support that extension continued at all six interboudin necks in the central SCS until ~23 Ma, when breakup by seafloor spreading propagation reached one of them. We propose that the seven segments evolved as discrete subsystems from early rifting to breakup. Structurally equivalent ultrathin crust grabens occur NE and SW of both SCS conjugate margins, supporting a 3D wide rift mode of deformation across the SCS rift system. The six ultrathin crust contemporaneous necks and the abrupt nature and location of the COT support that the breakup was not controlled by further continental lithospheric thinning but rather was determined by the seafloor spreading propagation toward the SW.

3D growth of silicon nanowires under pure hydrogen plasma at low temperature (250 °C)

The synthesis of silicon nanowires (SiNWs) is carried out at 250 °C under pure hydrogen plasma from monocrsytalline silicon substrates or amorphous silicon thin film, using indium as a catalyst. Studies have been carried out in function of the duration of the hydrogen plasma. The results showed a growth of smooth surface nanowire arrays (diameter 100 nm, length 500 nm) from an indium thickness of 20 nm and a hydrogen plasma duration of 30 min. The growth of nanowires for longer hydrogen plasma durations has led to SiNWs with larger diameters and rougher surfaces, revealing the onset of secondary nanowire growth on these surfaces, probably due to the presence of indium residues. The results present a new procedure for the 3D solid liquid solid growth mode of SiNWs.

Compact and broadband 3D mode (de)multiplexer via displacement of an asymmetric slot-strip coupler

A compact and broadband three-dimensional (3D) quasi- T E 0 and quasi- T E 1 mode (de)multiplexer [(De)MUX] is proposed via an asymmetric slot-strip coupler, in which the optimally lateral displacement between the bottom silicon slot waveguide and the upper poly-silicon strip-waveguide can enable the vertical mode-coupling efficiently. The design of the proposed 3D mode (De)MUX is based on the full-vectorial finite-element method, 3D full-vectorial finite-difference time-domain method, and mode expansion method. The optimized 3D mode (De)MUX is with a compact coupling length of only 5.65 µm, a broad 3 dB bandwidth of 231.5 nm, a low insertion loss of 0.3 dB, and a mode cross talk of − 27.54 d B . The fabrication tolerance is also studied with a width error of ± 20 n m for both the upper and lower layers.

Augmented Reality for Interactive Visualization of 3D Maxillofacial Prosthetic Data

To introduce an augmented reality (AR) application for students, patients, and practitioners to use to visualize a maxillectomy defect, the associated obturator prosthesis, and the eventual effects on the patient's facial appearance. Various 3D virtual models related to maxillectomy defects and their prosthetic rehabilitations were used to illustrate the handheld AR application. The AR "scene" was created using Vuforia and Unity3D software. Within this scene, 3D virtual models were linked to the target image by detecting a symbol track marker. The final file was saved as an installable application and exported for Android smart devices. The target image containing the maxillectomy defect and the prosthetic rehabilitation were successfully visualized interactively in 3D mode using the handheld AR maxillofacial prosthetic application. An AR application for visualizing maxillofacial prosthetic data could interestingly be developed as a pedagogic tool to explain prosthetic treatments.

A Method of Managing Technological Heredity in the Additive Growing of Objects from Cold-Resistant Materials on a Machine with Technology for Electric Arc Welding

The article considers the issue of managing print parameters to minimize the impact of technological heredity on the layers of the formed object. An analysis of the stability of the 3D printing process was carried out using acoustic emission data. The fractal dimensions of the acoustic emission attractor for a stable and unstable 3D printing process have been obtained. A method for controlling process stability by tracking 3D printing modes and assessing their stability using an artificial neural network is proposed. The mechanical properties of printed samples were evaluated under normal conditions and at low temperatures in the Arctic and the far north.

Assessing the earth dams’ effect on the groundwater of its location case study: Kord-Oliya dam

The main objective of the construction of the Kord-Oliya earth dam is to reserve surplus water for consumption and artificial recharge in the area. The effect of such dams on the basin is to alter the hydrological regime of its adjacent areas to somehow prevent drought. By considering the existence of such dams and the costs of their construction, operation, and maintenance, it is necessary to study their effect on surrounding groundwater. The objective of this study is to combine a geotechnical model for the subject earth dam through SEEP 3D software and its output in hydrogeological model through GMS software in a 3D mode for surface and groundwater management in a simultaneous manner. It is necessary to estimate the groundwater level of the area, to determine the hydrogeological and geotechnical conditions of the aquifer through mathematical models for optimal exploitation of the Karvan Plain. Excessive water harvesting for agriculture consumption from the Karvan aquifer has been and is on an increase which has led to a decrease in groundwater level in the area and introduced many environmental risks. This modeling is calibrated and validated for 121 months on this aquifer in both the steady and unsteady states in two scenarios with and without this earth dam. The obtained results indicate that existence of this dam does not increase the groundwater level in a gradual manner in the area in the consecutive years, while the mean groundwater level is on an increase by 14 m. By considering scenario one, the total volume of alluvial aquifer reserves increase 83.4 Mm3.

Identification of structural damage using S-transform from 1D and 2D mode shapes

An improvement of vibration-based damage identification in structures attracted much attention over the last decades. Many of the developed algorithms to-date, like those based on wavelet transforms (WTs), reveal high sensitivity to damage, however suffer from numerous drawbacks, which include significant dependency of a damage detectability on selection of a basis function or the boundary effect. This paper presents a novel alternative approach for damage identification in beams and plates based on the S-transform, which combines numerous advantages of the short-time Fourier transform and an ability of multiresolution analysis of WTs. The efficiency of the proposed approach was tested and validated on 1D and 2D mode shapes of various composite structures and various types of damage obtained both from numerical simulations and experimental studies. The obtained results confirmed high sensitivity of the approach based on the S-transform to structural damage as well as revealed full reduction of the boundary effect.

Speckle-tracking echocardiography in 3D mode in assessing the deformation of the myocardium and identifying subclinical cardiotoxicity during chemotherapy in breast cancer patients with arterial hypertension

Aim.To study the possibilities of speckle-tracking echocardiography (STE) in 3D mode in assessing the strain of the myocardium and identifying subclinical cardiotoxicity during anthracycline-containing chemotherapy in breast cancer patients with arterial hypertension.&#x0D; Materials and methods.The study included 47 patients with triple negative breast cancer (BC) with AH and normotension. All patients underwent transthoracic echocardiography with an assessment of the left ventricular (LV) ejection fraction, also used STE in three-dimensional mode with an assessment of global longitudinal (GLS), circular (GCS), radial (GRS) strain and a new strain parameter strain area (GAS).&#x0D; Results.In patients with BC for a more accurate assessment of LV systolic function, it is advisable to use 3D echocardiography. In BC patients with AH, the initial parameters of LV strain were statistically significantly worse than in patients with normotension and further deterioration was observed after chemotherapy. To determine the sensitivity and specificity of the strain parameters from the 3D-STE data, an ROC analysis was performed. The most diagnostically significant parameter of strain, as a marker of cardiotoxicity, was the global area strain (GAS), which with a cut-off value -14.0% showed a sensitivity equal to 81.5% and a specificity of 73.3%, but the value this parameter of LV deformation requires further study.&#x0D; Conclusion.In BC patients with AH and normotension it is advisable to use the STE in 3D mode to analyze the strain and systolic function of the LV during antitumor treatment. The method is promising for identifying subclinical cardiotoxicity, but further research is needed to develop diagnostic criteria.

Quantitative evaluation of different high-density 3D mapping modes for atrial and ventricular substrate assessment of cardiac arrhythmias with the HD grid catheter

BackgroundAtrial and ventricular arrhythmias significantly contribute to morbidity and mortality of patients with cardiac disease. Ablation of these arrhythmias has shown to improve clinical outcomes, yet targeted ablation strategies rely on proper mapping capabilities. In the present study, we compare different modes of high-resolution mapping in clinically relevant arrhythmias using HD grid. Methods and resultsUsing the Advisor™ HD Grid Mapping Catheter in either the standard, the wave (bipolar along spline and bipolar orthogonal) or the wave diagonal setting, low-voltage areas were determined. Low-voltage was defined as local electrograms with an amplitude <0.5 mV (bipolar; atria/ventricle) or <4 mV (unipolar; ventricle). Ultra high-density mapping in 47 patients with ventricular tachycardia, ventricular premature beats, atrial fibrillation and atrial tachycardia provided reliable information for the understanding of the arrhythmia mechanism resulting in safe ablation procedures. Regions of low voltage were significantly decreased by 14 ± 2% and 31 ± 3% with wave and wave diagonal settings as compared to standard settings, respectively. ConclusionSubstrate mapping and risk stratification relies on proper low voltage discrimination. Even though the Advisor™ HD Grid Mapping Catheter was safely used in all cases, the extent of low voltage areas was mapping-mode dependent.

The evaluation of corneal topographic parameters with corneal and lens densitometers in pediatric keratoconus.

The aim of this study was to compare corneal and lens densitometric measurements and corneal topographic parameters of pediatric keratoconus patients and healthy individuals. The data of the Pentacam® HR device and the database of our hospital between 2017 and 2019 were analyzed retrospectively. A total of 80 eyes of 47 keratoconus children (one eye of 14 children and two eyes of 33 children) in the Group KC (n = 80); and 74 eyes of 37 children were assessed in healthy children, Group HC (n = 74). The corneal density was measured manually in full-thickness cornea with a diameter of 2mm in the corneal apex. The lens density (LD) was measured manually in the pupillary area with a diameter of 2mm throughout the whole central lens thickness in 3D mode. The corneal density values were significantly higher in Group KC (12.72 ± 1.68, 1.00 ± 0.34, 16.36 ± 2.32, respectively) compared to Group HC (9.81 ± 1.02, 0.61 ± 0.28, 12.42 ± 1.44, respectively) (p < 0.001). LD-mean and LD-sd measurements were lower in Group KC (7.55 ± 0.48, 0.61 ± 0.49, respectively) compared to Group HC (7.75 ± 0.39, 0.81 ± 0.49, respectively) (p = 0.004, p = 0.014, respectively). It was found that corneal density increased and lens density decreased in pediatric keratoconus patients. These results showed that there may be factors that prevent or delay lens changes in isolated pediatric keratoconus patients.

Pränatale Diagnostik und postnatale Komplikationen im Fall einer extrem seltenen Tetraamelie

Tetra-amelia is extremely rare with an incidence of 2.4 per 10,000,000 births. It describes the absence of all 4 outer extremities and can be associated with other malformations. The boy presented here was diagnosed at 22 1/7 weeks of gestation by sonography in 2D and 3D mode. The parents decided to continue the pregnancy; vaginal birth occurred after external rotation at 38 1/7 weeks of pregnancy. Postnatally, surgical closure of a cleft of the soft palate was performed. External abnormalities manifested themselves increasingly in the area of the spine and the face. The anatomically limited psychomotor development of the child is supported by physiotherapy, occupational therapy, and speech therapy. Various aids enable the child to participate in activities appropriate to his age.

Spectroscopic Determination of Ice-Induced Interfacial Strain on Single-Layer Graphene.

Reliably determining the physical properties of ice (e.g., crystal structure, adhesion strength, interfacial state, and molecular orientation) has proven to be both challenging and highly dependent on experiment-specific conditions, including surface roughness, ice formation, water purity, and measurement method. Here, non-destructive measurements of single-layer graphene (SLG) interfaced with bulk ice are used to determine temperature-dependent, ice-induced strain and estimate ice-created strain elastic density in SLG. The use of SLG enables the precise study of interfacial strain by monitoring the 2D Raman mode. Upon ice formation, a clear, ≈2 cm-1 decrease in the 2D mode frequency is observed, which is ascribed to a 0.012% biaxial tensile shear strain at the ice-SLG interface. From this shear strain value, the ice-created SLG elastic strain energy density is estimated to be 2.4 μJ m-2 . In addition to these Raman strain measurements, intentionally ionized water is used to show that water-mediated charging of the SLG surface manifests itself in a distinctly different manner than ice-induced strain. Finally, the localized nature of the Raman probe is used to map SLG regions with and without ice, suggesting that this method cannot only determine ice-induced interfacial strain, but also correlate ice adhesion properties with surface roughness and topology.

3D Global Weak-Form Mesh-Free Method for Acoustic Attenuation Analysis of Expansion Chambers

In order to avoid the dependence of mesh method on grids, a 3D global weak-form mesh-free method (MFM) is applied to study the three-dimensional acoustic characteristics of silencers. For the expansion chamber silencers, the 3D acoustic modes are extracted and the transmission loss results are computed by using the 3D global weak-form (MFM), which is based on the radial basis function point interpolation method (RPIM) for calculating the shape functions and Galerkin method for discretizing the system equation. The first 15 order 3D acoustic modes and TL results of a special expansion chamber silencer are presented to validate the computational accuracy of the proposed technique, and the relative errors are controlled within 0.5% by comparing with the 3D finite element method (FEF) calculations. Additionally, the effects of axial modes on the acoustic characteristics are investigated, and the pass through frequencies can be eliminated to enhance the acoustic attenuation performance by locating the side branch outlet on the nodal lines of axial modes.

Transition to chaos in the wake of a circular cylinder near a moving wall at low Reynolds numbers

Floquet stability analysis has been employed to identify modes of three-dimensional (3D) instability in the flow over a circular cylinder of diameter D above a moving wall at a gap height of G = 0.2D, beyond the onset of two-dimensional vortex shedding. Two subharmonic modes (mode C1 and mode C2) and one long-wavelength quasi-periodic mode (mode QPL) are revealed. The characteristics of these 3D modes are discussed in detail. The results of 3D direct simulations show that it is the intensively nonlinear modal interactions that lead to a chaotic final flow state at higher Reynolds numbers, rather than the interference of the shear layer caused by the no-slip moving wall.

Comparative assessment of the surface topography for different optical profilometry techniques after dry turning of Ti6Al4V titanium alloy

This paper presents comparison analysis of the surface texture properties measured by a Sensofar S Neox 3D optical profilometer, an Alicona Infinite Focus SL optical measuring system and a digital Keyence VHX-6000 microscope on the example of assessing of the Ti6Al4V titanium alloy surface after finish turning under dry machining conditions. 2D and 3D surface parameters were analyzed and surface profiles and average percentage changes in parameters tested are demonstrated. Different measurement areas were used. Measuring differences of up to ~30% were observed between methods tested. In the 2D mode, the best possibilities are offered smaller measuring areas as observed for Alicona Infinite Focus SL and Keyence VHX-6000. In the 3D mode, larger measuring areas for Sensofar S Neox 3D provides better options compared to smaller measuring areas for Alicona Infinite Focus SL. Surface profiles analyses using the Sensofar S Neox 3D and Keyence VHX-600 show similar results.