Surface Mapping Research Articles

The lifts of surfaces in neutral 4-manifolds into the 2-Grassmann bundles

A twistor lift of a space-like or time-like surface in a neutral hyperKähler 4-manifold with zero mean curvature vector is given by a (para)holomorphic function, which yields (para)holomorphicity of the Gauss maps of space-like or time-like surfaces in E24 with zero mean curvature vector. For a space-like or time-like surface in an oriented neutral 4-manifold with zero mean curvature vector such that both twistor lifts belong to the kernel of the curvature tensor, its (para)complex quartic differential is holomorphic. If both twistor lifts of a time-like surface with zero mean curvature vector have light-like or zero covariant derivatives, then either the shape operator with respect to a light-like normal vector field vanishes or all the shape operators of the surface are light-like or zero. Examples with the former (resp. latter) property are given by the conformal Gauss maps of time-like surfaces of Willmore type with zero paraholomorphic quartic differential (resp. time-like surfaces in 4-dimensional neutral space forms based on the Gauss-Codazzi-Ricci equations).

Assessment of the Electron Correlation Treatment on the Quantum-Classical Dynamics of Retinal Protonated Schiff Base Models: XMS-CASPT2, RMS-CASPT2, and REKS Methods.

We compare the performance of three different multiconfigurational wave function-based electronic structure methods and two implementations of the spin-restricted ensemble-referenced Kohn-Sham (REKS) method. The study is characterized by three features: (i) it uses a small set of quantum-classical trajectories rather than potential energy surface mapping, (ii) it focuses, exclusively, on the photoisomerization of retinal protonated Schiff base models, and (iii) it probes the effect of both methyl substitution and the increase in length of the conjugate π-system. For each tested method, the corresponding analytical gradients are used to drive the quantum-classical (Tully's FSSH method) trajectory propagation, including the recent multistate XMS-CASPT2 and RMS-CASPT2 gradients. It is shown that while CASSCF, XMS-CASPT2, and RMS-CASPT2 yield consistent photoisomerization dynamics descriptions, REKS produces, in some of these systems, qualitatively different behavior that is attributed to a flatter and topographically different excited state potential energy surface. The origin of this behavior can be traced back to the effect of the employed density functional approximation. The above studies are further expanded by benchmarking, at the CASSCF and REKS levels, the electronic structure methods using a QM/MM model of the visual pigment rhodopsin.

Nucleophilic transformation of 3-substituted-6,8-dimethylchromones with phenylhydrazine under various reaction conditions: Theoretical, spectroscopic characterization and in silico ADME studies

The chemical behavior of 3-substituted-6,8-dimethylchromones 1–3 was examined towards phenylhydrazine under various reaction conditions. Under different molar ratio, reaction of aldehyde 1 with phenylhydrazine produced hydrazone 4 and pyrazole 5. Depending on the solvent used, reacting carbonitrile 2 with phenylhydrazine produced a variety of products; through ring-opening and ring-closure mechanisms. Reaction of carboxamide 3 with phenylhydrazine, afforded chromeno[4,3-c]pyrazole derivative 8. Finally, boiling carboxamide 3 in KOH solution gave 4-hydroxy-6,8-dimethylcoumarin-3-carboxaldehyde (9). Molecular geometries were examined using density functional theory, (DFT/B3LYP) with 6–311 G(d,p) basis sets, to investigate the bond lengths of certain bonds. DFT was also used to compute some global reactivity descriptors including electronegativity (χ), chemical potential (μ), electrophilicity index (ω), softness (S) and hardness (η). Compound 4 is the softest, while compound 9 is more electrophilic and more electronegative. In addition, MEP surface maps were investigated to predict the chemical reactivity of the current molecules. The chemical shifts values of 1H and 13C NMR were assessed utilizing the GIAO method, and the results were compared with those obtained experimentally. The current compounds are appropriate for non-linear optical applications, according to their first order hyperpolarizability values which found 1.5–3 times greater than those of urea. SwissADME was used to explore the features of current compounds' absorption, delivery, metabolism, and excretion (ADME).

Analisis Spasial Kenaikan Tinggi Permukaan Air Batang Sumani Menggunakan Model Permukaan Digital

The occurrence of flooding in the Batang Sumani area of ​​Solok Regency is caused by several things, including the low slope of the river, the river cross-section which is not wide enough, the topography of the plains, heavy bends along the river and silting due to sedimentation and the vulnerability to flood hazards which is quite high in the watershed area. The influence of the topography of the plains causes inundation on land managed and used by the community. In accordance with technological developments in digital mapping of the earth's surface, the earth's surface can be presented in the form of a three-dimensional map called a Digital Elevation Model (DEM). This DEM is used as a model, analysis and representation of conditions related to the earth's surface. The use of DEM in the process of analyzing inundation caused by surface runoff will help in identifying the coverage of inundation areas and water catchment areas. By using the Simulate water level rise / flooding analysis from the Global Mapper application it is possible to simulate water level rise / flooding which makes it possible to simulate the coverage or spread of water/flooding by increasing the water level to a certain depth and spatial analysis using the Geographic Information System can see the influence of the inundation area on land use managed by the community around the inundation area. So that the location and coverage of the inundation on land use can be obtained. Most of the inundation areas are in garden areas at 37.56%, rice fields at 23.83%, fields at 24.03% and residential areas at 13.67%. There was a significant increase in the water level rise of 2 meters.

ПРИМЕНЕНИЕ КРОССПЛАТФОРМЕННОГО ПРИЛОЖЕНИЯ GNUPLOT ДЛЯ ВИЗУАЛИЗАЦИИ ОБЛАСТЕЙ РАДИАЦИОННОГО ЗАРАЖЕНИЯ

The authors of the article have developed an automated decision support system for performing tasks to prevent and eliminate an emergency situation associated with the explosion of a «dirty» nuclear bomb for employees of the CCS of the territorial bodies of EMERCOM of Russia. An integral part of this system is a cross-platform application that allows you to visualize the pollution field during remote ecological mapping of the Earth's surface or object. The application is made in the C# programming language using the Gnuplot graphical utility. The Gnuplot utility is a cross-platform unified application for building all types of graphs. 
 At the moment, using the Gnuplot utility, a large library of programs has been developed with the ability to solve various mathematical problems, including problems on statistics, visualization and approximation of data, performed in different programming languages, such as C#, Python, etc.

94 GHz Radar Backscatter Characteristics of Alpine Glacier Ice

AbstractMeasuring the radar backscatter characteristics of glacier ice at different frequencies and incidence angles is fundamental to predicting the glacier mapping performance of a sensor. However, such measurements at 94 GHz do not exist. To address this knowledge gap, we collected 94 GHz radar backscatter data from the surface of Rhônegletscher in Switzerland using the All‐Weather Volcano Topography Imaging Sensor (AVTIS2) real‐aperture Frequency Modulated Continuous Wave radar. We determine the mean normalized radar cross section to be −9.9 dB. The distribution closely follows a log‐normal distribution with a high goodness of fit (R2 = 0.99) which suggests that radar backscatter is diffuse and driven by surface roughness. Further, we quantified the uncertainty of AVTIS2 3D point clouds to be 1.30–3.72 m, which is smaller than other ground‐based glacier surface mapping radars. These results demonstrate that glacier surfaces are an efficient scattering target at 94 GHz, hence demonstrating the suitability of millimeter‐wave radar for glacier monitoring.

Geothermal prospective areas in the Northern sector of Bida Basin and environs, North-Central Nigeria

With the deteriorating electrical power supply in Nigeria, it is imperative that more alternative sources are explored. This research work is carried out to assess part of the Bida basin as a possible source of geothermal energy that will help to augment the electric power generation in the country. The study was carried out within the northern sector of the Bida Basin and environs and the area which lies between Longitudes 5000ʹ00ʺ – 7000ʹ00ʺ E and Latitudes 8030ʹ00ʺ – 10030ʹ00ʺ N. Sixteen (16) half degree high resolution aeromagnetic data in a block grid format was utilised for this research. To enhance data for interpretation the total magnetic intensity (TMI) map was subjected to regional-residual separation using Oasis Montaj (version 7.0.1) software. To minimize the effect of frequency noise caused by tiny structures near ground surface, the residual magnetic map was upward continued and further divided into sixteen square blocks with each block windowed and subjected to spectral analysis using Matlab (version R2010a) software. Surfer 11 surface mapping software was used for data contouring. Results obtained from the analysis revealed a Curie point depths ranges from 9 – 17 km over the study area, a geothermal gradient range from 32 – 65 0C km-1, and heat flow ranges from 83 – 163 mWm-2. From interpretation of heat flow map, the prospective areas with anomalous geothermal conditions recommended for geothermal exploitation are areas around Masamagu, Mokwa, Bokani, Lapai, Agaie and Agena.

A U-Net Approach for InSAR Phase Unwrapping and Denoising

The interferometric synthetic aperture radar (InSAR) imaging technique computes relative distances or surface maps by measuring the absolute phase differences of returned radar signals. The measured phase difference is wrapped in a 2π cycle due to the wave nature of light. Hence, the proper multiple of 2π must be added back during restoration and this process is known as phase unwrapping. The noise and discontinuity present in the wrapped signals pose challenges for error-free unwrapping procedures. Separate denoising and unwrapping algorithms lead to the introduction of additional errors from excessive filtering and changes in the statistical nature of the signal. This can be avoided by joint unwrapping and denoising procedures. In recent years, research efforts have been made using deep-learning-based frameworks, which can learn the complex relationship between the wrapped phase, coherence, and amplitude images to perform better unwrapping than traditional signal processing methods. This research falls predominantly into segmentation- and regression-based unwrapping procedures. The regression-based methods have poor performance while segmentation-based frameworks, like the conventional U-Net, rely on a wrap count estimation strategy with very poor noise immunity. In this paper, we present a two-stage phase unwrapping deep neural network framework based on U-Net, which can jointly unwrap and denoise InSAR phase images. The experimental results demonstrate that our approach outperforms related work in the presence of phase noise and discontinuities with a root mean square error (RMSE) of an order of magnitude lower than the others. Our framework exhibits better noise immunity, with a low average RMSE of 0.11.

Relative Sea-Level Rise Projections and Flooding Scenarios for 2150 CE for the Island of Ustica (Southern Tyrrhenian Sea, Italy)

The island of Ustica (Italy) is constantly exposed to the effects of sea-level rise, which is threatening its coastal zone. With the aim of assessing the sea levels that are anticipated by 2150 CE under the climatic projections shown in the AR6 report from the IPCC, a detailed evaluation of potential coastal flooding under different climatic scenarios and the ongoing land subsidence has been carried out for three coastal zones. Scenarios are based on the determination of the current coastline position, a high-resolution digital terrain and marine model, and the SSP1-2.6, SSP3-7.0, and SSP5-8.5 climatic projections. Relative sea-level rise projections allowed the mapping of the potential inundated surfaces for 2030, 2050, 2100, and 2150. The results show rising sea levels for 2150, ranging from a minimum of 66 ± 40 cm (IPCC AR6 SSP2.6 scenario) to a maximum of 128 ± 52 cm (IPCC AR6 SSP8.5 scenario). In such conditions, considering the SSP8.5 scenario during storm surges with return times (RTs) of 1 and 100 years, the expected maximum wave run-up along the island may vary from 3 m (RT = 1) to 14 m (RT = 100), according to the coastal morphology. Our results show that adaptation and mitigation actions are required to protect the touristic and harbor installations of the island.

Spatial-temporal Trends Mapping and Geostatistical Modelling of Groundwater Level Depth Over Northern Parts of Indo-Gangetic Basin, India

Haryana-Punjab is a vast part of the Indo-Gangetic basin (India), recognised globally as a major hotspot of groundwater abstraction and agricultural economic reliance. A lack of information is present in this region regarding spatiotemporal changes in groundwater levels. Geostatistical anisotropic processes are reliable, especially when the monitored regions are extensive. The modelling study involves a twofold objective. First, it estimates and evaluates anisotropic spatial variations in groundwater level depth (GWD, Surface to water level) using geostatistics for all four seasons of Indian cropping patterns—pre-monsoon, monsoon, post-monsoon (rabi) and post-monsoon (Kharif), and parameters of point kriging cross-validation (PKCV) are optimum, acceptable, and support the unbiasedness hypothesis of kriging. Based on the PKCV, five essential parameters were computed to accept the anisotropy semi-variogram fitted model. These are (1) kriging mean error (KME), ideally close to zero so that there are no over or underestimates, (2) goodness of fit (R2), (3) the ratio of estimated variance (EV) to kriging variance (KV) lies between 0.95-1.05, (4) good eye visualisation fit and (5) significant t-test on the correlation coefficient. The second objective is spatiotemporal modelling, a pixel-based Mann-Kendall trend testing (at 95% Confidence Interval) on kriged raster surfaces of GWD (For all four seasons) at 1km grid resolution. The trend, significant or not, is determined by the Mann-Kendall test, while Sen's slope estimator determines the slope magnitude of the trend. Results revealed that the study area's east-central to the central-northern region comes under a high depletion zone for groundwater levels. GWD significantly increased by 120cm/year-80cm/year in this region, and the mean kriged GWD for the entire study area increased by 30cm/year-29cm/year over 25 years. Seasonal climatological mean maps of kriged surfaces of GWD and mean rainfall surfaces in two different time phases for all four seasons have been evaluated. It is observed from these maps that wherever the rainfall is increasing, GWD is decreasing. Results clarified that anisotropic semi-variogram modelling with kriging, pixel-based trend analysis, and regression studies is a valuable tool for identifying the critical region of groundwater levels, and the central region of the study area falls under the severe depletion condition of the groundwater level.

HP-LSP: A reference of land surface phenology from fused Harmonized Landsat and Sentinel-2 with PhenoCam data

Land surface phenology (LSP) products are currently of large uncertainties due to cloud contaminations and other impacts in temporal satellite observations and they have been poorly validated because of the lack of spatially comparable ground measurements. This study provided a reference dataset of gap-free time series and phenological dates by fusing the Harmonized Landsat 8 and Sentinel-2 (HLS) observations with near-surface PhenoCam time series for 78 regions of 10 × 10 km2 across ecosystems in North America during 2019 and 2020. The HLS-PhenoCam LSP (HP-LSP) reference dataset at 30 m pixels is composed of: (1) 3-day synthetic gap-free EVI2 (two-band Enhanced Vegetation Index) time series that are physically meaningful to monitor the vegetation development across heterogeneous levels, train models (e.g., machine learning) for land surface mapping, and extract phenometrics from various methods; and (2) four key phenological dates (accuracy ≤5 days) that are spatially continuous and scalable, which are applicable to validate various satellite-based phenology products (e.g., global MODIS/VIIRS LSP), develop phenological models, and analyze climate impacts on terrestrial ecosystems.

Complex Study of the Composite Building Material Based on Flax Straw Organic Waste: Hygrothermal and Physicochemical Properties

The focus of this study is on the hygrothermal and mechanical properties of the elaborated insulating composite based on flax straw. Flax straw is considered as an agricultural waste of organic origin, which has a high sorption capacity and a low thermal conductivity potential due to its natural porosity. Investigations on sorption moisture, thermal conductivity and mechanical properties under laboratory conditions have allowed us to develop a perspective building material suitable for use in ‘green’ construction, especially in rural areas, due to the relative accessibility of the base component. Liquid glass is proposed as a binder. The optimal composition of the filler and binder, sorption moisture, thermal conductivity and surface mapping of the proposed material were investigated. The thermal conductivity reached a minimum value of 0.0728 W m−1 K−1 at relative humidity of 50% during desorption, which is highly competitive to the values for conventional insulation materials on an organic basis. The binder was visually distributed evenly over the surface according to the SEM analysis. Corresponding to the spectral analysis by chemical elements, Na and SiO2 in total showed 17.69% quantity volume on the composite surface of 2–5 μm in depth.Graphical

Evaluating the Impact of Redox Potential on the Corrosion of Q125, 316L, and C276 Steel in Low-Temperature Geothermal Systems

Time series experiments were used to explore the fluid redox impact on the corrosion of Q125, 316L, and C276 steels in low-ionic-strength and neutral water at temperature and pressure conditions associated with low-temperature geothermal systems. After exposing polished samples of each steel grade to an oxidizing (H2O2) and a reducing (Zn-doped) fluid for intervals of 24 h, 1 week, and 6 weeks, the atomic force microscopy results revealed general corrosion for Q125, while 316L and C276 exhibited pitting, crevice expansion, and edge attack corrosion. Secondary depositional features are frequently found as topographic highs, adjacent to pitting corrosion. These features may be identified as there is a very strong spatial correlation between the height retrace and phase retrace surface maps. All steels became progressively rougher over time after exposure to both fluids, while the corrosion rates were more complex. Samples exposed to the reducing fluid experienced an increase in the corrosion rate over time, while C276 and 316L experienced a decrease in the corrosion rate. Finally, a novel data validation technique was developed to address the intrinsic scalability of corrosion. The results indicate that the AFM scan area does not affect the measured surface roughness over nearly three orders of magnitude.

Instance-based learning with prototype reduction for real-time proportional myocontrol: a randomized user study demonstrating accuracy-preserving data reduction for prosthetic embedded systems

This work presents the design, implementation and validation of learning techniques based on the kNN scheme for gesture detection in prosthetic control. To cope with high computational demands in instance-based prediction, methods of dataset reduction are evaluated considering real-time determinism to allow for the reliable integration into battery-powered portable devices. The influence of parameterization and varying proportionality schemes is analyzed, utilizing an eight-channel-sEMG armband. Besides offline cross-validation accuracy, success rates in real-time pilot experiments (online target achievement tests) are determined. Based on the assessment of specific dataset reduction techniques’ adequacy for embedded control applications regarding accuracy and timing behaviour, decision surface mapping (DSM) proves itself promising when applying kNN on the reduced set. A randomized, double-blind user study was conducted to evaluate the respective methods (kNN and kNN with DSM-reduction) against ridge regression (RR) and RR with random Fourier features (RR-RFF). The kNN-based methods performed significantly better (p < 0.0005) than the regression techniques. Between DSM-kNN and kNN, there was no statistically significant difference (significance level 0.05). This is remarkable in consideration of only one sample per class in the reduced set, thus yielding a reduction rate of over 99% while preserving success rate. The same behaviour could be confirmed in an extended user study. With k=1, which turned out to be an excellent choice, the runtime complexity of both kNN (in every prediction step) as well as DSM-kNN (in the training phase) becomes linear concerning the number of original samples, favouring dependable wearable prosthesis applications.Graphical abstract

Atomistic-Level Effects of Noncovalent Interactions and Crystalline Packing for Organic Material Structural Integrity upon Exposure to Gamma Radiation.

Developing an atomistic understanding of ionizing radiation induced changes to organic materials is necessary for intentional design of greener and more sustainable materials for radiation shielding and detection. Cocrystals are promising for these purposes, but a detailed understanding of how the specific intermolecular interactions within the lattice upon exposure to radiation affect the structural stability of the organic crystalline material is unknown. This study evaluates atomistic-level effects of γ radiation on both single- and multicomponent organic crystalline materials and how specific noncovalent interactions and packing within the crystalline lattice enhance structural stability. Dose studies were performed on all crystalline systems and evaluated via experimental and computational methods. Changes in crystallinity were evaluated by p-XRD and free radical formation was analyzed via EPR spectroscopy. Type of intermolecular interactions and packing within the crystal lattice was delineated and related to the specific free radical species formed and the structural integrity of each material. Periodic DFT and HOMO-LUMO surface mapping calculations provided atomistic-level identifications of the most probable sites for the radicals formed upon exposure to γ radiation and relate intermolecular interactions and molecular packing within the crystalline lattice to experimental results.

Comparative analysis of alignment algorithms for macular optical coherence tomography imaging

BackgroundOptical coherence tomography (OCT) is the most important and commonly utilized imaging modality in ophthalmology and is especially crucial for the diagnosis and management of macular diseases. Each OCT volume is typically only available as a series of cross-sectional images (B-scans) that are accessible through proprietary software programs which accompany the OCT machines. To maximize the potential of OCT imaging for machine learning purposes, each OCT image should be analyzed en bloc as a 3D volume, which requires aligning all the cross-sectional images within a particular volume.MethodsA dataset of OCT B-scans obtained from 48 age-related macular degeneration (AMD) patients and 50 normal controls was used to evaluate five registration algorithms. After alignment of B-scans from each patient, an en face surface map was created to measure the registration quality, based on an automatically generated Laplace difference of the surface map–the smoother the surface map, the smaller the average Laplace difference. To demonstrate the usefulness of B-scan alignment, we trained a 3D convolutional neural network (CNN) to detect age-related macular degeneration (AMD) on OCT images and compared the performance of the model with and without B-scan alignment.ResultsThe mean Laplace difference of the surface map before registration was 27 ± 4.2 pixels for the AMD group and 26.6 ± 4 pixels for the control group. After alignment, the smoothness of the surface map was improved, with a mean Laplace difference of 5.5 ± 2.7 pixels for Advanced Normalization Tools Symmetric image Normalization (ANTs-SyN) registration algorithm in the AMD group and a mean Laplace difference of 4.3 ± 1.4.2 pixels for ANTs in the control group. Our 3D CNN achieved superior performance in detecting AMD, when aligned OCT B-scans were used (AUC 0.95 aligned vs. 0.89 unaligned).ConclusionsWe introduced a novel metric to quantify OCT B-scan alignment and compared the effectiveness of five alignment algorithms. We confirmed that alignment could be improved in a statistically significant manner with readily available alignment algorithms that are available to the public, and the ANTs algorithm provided the most robust performance overall. We further demonstrated that alignment of OCT B-scans will likely be useful for training 3D CNN models.

Topography and Morphometrics of the Cartilage Surfaces in the Peritalar Joints

Category: Hindfoot; Ankle Introduction/Purpose: Recent studies have highlighted the important role of peritalar joint congruence in maintaining the alignment of the hindfoot. Peritalar subluxation is associated with a variety of pathological deformities including flatfoot, cavovarus foot, clubfoot, as well as foot and ankle stress fractures. To date, studies of peritalar joint congruence have all been performed using either XR, WBCT based direct measurements, or 3D segmentation and analysis. However, none of these techniques can demonstrate the cartilage location nor disruption, nor the exact location of the articulation on the bone surface. Data bias caused by the limitations of these study methodologies is therefore inevitable. This study used 3D surface mapping to assess morphometrics of the cartilage surfaces of the peritalar joints. Methods: 11 fresh-frozen cadaveric feet without trauma nor surgery or significant deformities were dissected to expose the calcaneus, cuboid, talus, and navicular bones, and the articular surfaces. Surface mapping of the articular surfaces and the two bones was completed using an Artec Space Spider 3D scanner and Mmics. Further digital analysis was completed using GeoMagic Studio 10. T-test was used for statistical comparisons, with p&lt; 0.05 as statistically significantly different. Results: Detailed information of the articular surfaces is summarized in Table 1. The average articular area on both sides of the joint matched each other well in the posterior facet of the subtalar joint (4% difference), and calcaneocuboid joint (3% difference) without significant statistical difference, but not in the anterior &amp; middle facets of the subtalar joint, nor the talonavicular joint. In the anterior &amp; middle facets of the subtalar joint, the cartilage articular area on the talar side was 124% of that on the calcaneus (p &lt; 0.05), and in the talonavicular joint the cartilage articular area on the navicular was 138% of that on the talus (p &lt; 0.05). Conclusion: The cartilage articular surfaces in certain peritalar joints do not match its opposing surface in size. In the talonavicular joint, it is easy to understand since area of the socket must be much smaller than that of the ball in order for the joint to glide and rotate. There must be functional reasons for this phenomenon to happen in the anterior and middle facets of the subtalar joint, which need further investigation. This study shows that the extent of subluxation of the peritalar joints may be physiological and should not necessarily be considered as pathological.

A Lidar-Assisted Self-Localization Technology for Indoor Wireless Sensor Networks

The self-localization of wireless sensor networks (WSNs) is facing the problem of insufficient positioning accuracy in indoor environment due to multipath and interference issues. At the same time, without external references, through mutual measurement nodes can calculate only a set of relative coordinates. Therefore, it is difficult to achieve the mapping of coordinate values to the physical world. The development of simultaneous localization and mapping (SLAM) technologies has provided new opportunities to solve the above problems by making it easier to obtain real-time indoor maps. This paper proposes a Lidar-assisted self-localization (LASL) technique to further improve the localization accuracy of WSNs in indoor scenes by combining spatial constraint information obtained from real-time maps, and to place the relative node coordinate network in the visualized maps. Based on the general assumption that the nodes are deployed on the surface of the object, the proposed technique combines the spatial constraints obtained by plane fitting of a local point cloud map (PCM) and finite area approximation of object surfaces with the distance constraints provided by radio ranging. Subsequently, the self-localization results under the joint constraints are solved by the alternating coordinate descent (ACD) method. Simulations and experiments demonstrate that the proposed technique can effectively combine the spatial constraints provided by the Lidar PCM to further improve the self-localization accuracy of the sensor nodes, and further optimize the relative position relationship between each node and the map environment to achieve better matching and integration of the WSN and the real-time map.

The Effect of Rotary Friction Welding Conditions on the Microstructure and Mechanical Properties of Ti6Al4V Titanium Alloy Welds.

The main task that the article introduces is the experimental study of how the geometry of contact surfaces affects the quality and mechanical properties of a rotary friction weld (RFW), as well as the findings of whether the RFW technology is suitable for the titanium alloy Ti6Al4V. The experiments were carried out for specimens with a diameter of 10 mm and were performed at 900 RPM. Three types of geometry were proposed for the RFW process: flat on flat, flat on 37.5° and flat on 45°. Based on these results, the best tested flat geometry was selected from the perspective of quality and economic efficiency. The welded joints were subjected to microstructural analysis, tensile testing, microhardness testing, and fractography, as well as spectral analysis of the fracture surface and EDS map analysis of oxygen. The flat geometry of the contact surface resulted in the least saturation with interstitial elements from the atmosphere. Fracturing in the RFW zone led to a brittle fracture with a certain proportion of plastic deformation. A pure ductile fracture occurred in specimens fractured in the HAZ region, where the difference in UTS values compared to specimens fractured by a brittle fracture mechanism was not significant. The average UTS value was 478 MPa.

Robustness Analysis of Reference Surfaces for Surface Guided Radiation Therapy of the Breast

Surface guided radiation therapy (SGRT) implements an optical imaging system in radiation therapy for positioning and motion management. This system projects visible light onto a patient and the reflected light is used to generate 3D positional information so that clinicians can accurately reproduce body positions. Patient setup shifts are calculated with six degrees of freedom by a registration algorithm comparing a reference surface (RS) of the patient to a live surface map of the patient on treatment day. SGRT has been an effective tool in daily localization for the treatment of breast cancer patients. It is common for patients to have multiple RS throughout the course of their treatment to account for anatomical variation between fractions. We sought to evaluate the robustness of reference surfaces and vendor specific algorithms used for SGRT. At our institution, positional shift data for five patients treated for right-sided breast cancer were retrospectively analyzed. SGRT performance was compared between RS using bilateral breasts or a single ipsilateral breast. Shift parameters were calculated over the entire treatment course for all patients with a vendor supplied software tool that offers rigid and deformable registration algorithms. The deformable algorithm was used for treatment setups, with the treatment RS encompassing both breasts plus a margin. Two robustness tests were carried out: 1) a trimmed down RS encompassing just the ipsilateral breast and 2) a comparison of deformable vs rigid registration of the clinically used RS. After obtaining translational and angular shift data, the absolute mean differences between shifts were calculated to compare differences between RS size and algorithm performance. On average, 1.4 new RS were created per patient guided by weekly radiographic imaging to adjust for anatomical changes. The absolute value of the average of the discrepancies between shifts using the clinical RS subtracted from the trimmed external (89 fractions) were <1mm and 1° and the maximum differences were: Lateral: 2.6mm, Longitudinal: 1.4mm, Vertical: 1.1mm, Yaw: 1.1°, Roll: 1.5°, Pitch: 1.7°. Discrepancies between tracking algorithms (83 fractions) were <1.5mm and 1° and the maximum differences were: Lateral: 3.4mm, Longitudinal: 3.5mm, Vertical: 2.0mm, Yaw: 2.4°, Roll: 2.7°, Pitch: 1.9°. Clinically negligible mean discrepancies were observed for both robustness tests showing that neither the reference surface size nor the algorithms investigated caused systematic variations in the shifts for this group of patients. Maximum discrepancies of up to 3 mm and 3° were found between the algorithms, which indicate some variation, but within clinical tolerance. Overall, different selection of reference surfaces and algorithms had a minor effect on clinical shifts for SGRT of the breast.