Shadow Effect Research Articles

Person Fall Detection System Based on Video Stream Analysis

The purpose of this paper is to develop an information system that would detect a fall based on video stream analysis. This work contains research and a description of the subject environment and the structure of the system. An analysis of current scientific works in this area was conducted, which allowed defining the purpose and primary objectives of the thesis. In addition, this analysis showed that this system would be in demand in the market of software that uses computer vision. The practical significance of the results can be determined by the fact that the proposed application performs on the level of other research works in this field and can be used by a broad market of customers. We applied pre-trained TensorFlow Lite CNN real-time model PoseNet to detect keypoints of a subject. Keypoints sequence is analyzed by LSTM as it works best when processing long sequences of data. The system was trained using a combination of the two biggest fall detection datasets. The system extracts the locations of 17 joint points of the human body and recognizes human movement by detecting the joint point location changes. By using joint points location as input to LSTM, the training and inference time was improved drastically. It also helped minimize the adverse effects of light sources and shadows

Can the use of the CROS system provide head shadow effect contribution to unilateral Cochlear Implant Users?

The aim of this study was to evaluate the contribution of the CROS system on the head shadow effect in unilateral implant users. Prospective cross-sectional study, approved by the ethics committee under protocol 2.128.869. Eleven adults with post-lingual deafness users of unilateral Advanced Bionics CI were selected. Speech recognition was evaluated with recorded words presented at 65dBA at 0o azimuth and at 90o on the side contralateral to the CI, with noise at 55dBA, using CI alone and CI + CROS system. The results were analyzed using paired t-test with a 0.05 alpha. The mean speech recognition scores were significantly better with CI + CROS in relation to the condition of CI alone (p <0.05, p <0.005 and p <0.005 respectively). In the presentation at 0o azimuth, no significant differences were found. Users of unilateral CI without useful residual hearing for the use of hearing aids or unable to undergo bilateral surgery can benefit from the CROS device for speech recognition, especially when the speech is presented on the side contralateral to the CI.

MFFENet: Multiscale Feature Fusion and Enhancement Network For RGB–Thermal Urban Road Scene Parsing

Compared with traditional handcrafted features, deep learning has greatly improved the performance of scene parsing. However, it remains challenging under various environmental conditions caused by imaging limitations. Thermal imaging cameras have several advantages over cameras for the visible spectrum, such as operation in total darkness, robustness to shadow effects, insensitivity to illumination variations, and strong ability to penetrate smog and haze. These advantages of thermal imaging cameras make them ideal for the scene parsing of semantic objects in daytime and nighttime. In this paper, we propose a novel multiscale feature fusion and enhancement network (MFFENet) for accurate parsing of RGB&#x2013;thermal urban road scenes even when the quality of the available RGB data is compromised. The proposed MFFENet consists of two encoders, a feature fusion layer, and a multi-label supervision layer. We concatenate the multi-scale features with the features that contain global semantic information. Furthermore, we explore the cross-modal fusion of RGB and thermal features at multiple stages, rather than fusing them once at the low or high stage. Then, we propose a spatial attention mechanism module that provides a higher weight to (focuses more on) the foreground area, allowing MFFENet to emphasize foreground objects. Finally, multi-label supervision is introduced to optimize parameters of the proposed MFFENet. Experimental results confirm that the proposed MFFENet outperforms similar high-performing methods.

Percutaneous Bone-Anchored Hearing Implant: Is It Clinically Useful in Korean?

BackgroundThe aim of this study is to investigate the clinical effectiveness of Ponto in Korea, a recently released percutaneous bone-anchored hearing implant.Methods16 patients with single-sided deafness (SSD) and mixed or conductive hearing loss who underwent Ponto implantation from December 2018 to September 2020 were enrolled in the study. Puretone audiometry, the Korean version of the Hearing in Noise Test (K-HINT), sound localization test (SLT), and Pupillometry were performed pre- and three months post-operation. Standardized questionnaires, the Hearing Handicap Inventory for the Elderly (HHIE) and Speech, Spatial and Qualities of Hearing Scale (SSQ), were administered.ResultsThe mean age of subjects was 55.5 (range, 48–67) years. Four males and 12 females participated in the study. The mean puretone average was 73.17 dB hearing level (HL) before surgery and significantly improved to 36.72 dB HL three months after surgery. The mean word recognition score improved from 26.0% to 90.75% after implantation. In the case of K-HINT, there was a significant difference in summation (Z = −2.250, P = 0.024) and head shadow effects (Z = −3.103, P = 0.002). There was no significant difference in root mean square error degree (RMSE) and hemifield identification scores for SLT testing. Pupillometry was performed to measure listening effort and the results revealed that the degree of pupillary dilatation decreased under the condition of quiet, 0 dB signal to noise ratio (SNR) and 3 dB SNR. The total score for HHIE decreased significantly (Z = −3.130, P = 0.002) while the SSQ score increased significantly (Z = −2.216, P = 0.027).ConclusionsThe Ponto bone-anchored hearing system showed significant clinical benefit in Korean patients with conductive and mixed hearing loss and SSD.

Evaluation of Shadow Effects on Remotely Sensed Reflectance from Permafrost Thaw Lakes in the Subarctic Forest-Tundra Zone

Evaluation of Shadow Effects on Remotely Sensed Reflectance from Permafrost Thaw Lakes in the Subarctic Forest-Tundra Zone

Fatigue acid fracturing: A method to stimulate highly deviated and horizontal wells in limestone formation

As a fundamental technique to stimulate limestone formations, acid fracturing is now facing the problem of high fracture pressure. The fatigue damage in steel is a powerful strategy to reduce strength. And acidizing is the key step of acid fracturing and a useful tool to minimize limestone fracture pressure. Therefore, the combination of acid fracturing and fatigue treatment was investigated in this study. In addition, the interaction between acid fractures and calcite veins and weathering zones is still unclear. And the geometry of acid fractures in highly deviated wells hasn't been investigated in detail. Hence, there are three primary aims of this study: 1. To investigate the specific performance of fatigue acid fracturing in the limestone. 2. To ascertain the interaction between acid fractures and calcite veins and weathering zones. 3. To clarify the acid fractures morphology in highly deviated wells. Based on the tri-axial acid fracturing system, a sequence of conventional acid fracturing and fatigue acid fracturing experiments were carried out in vertical, highly deviated, and horizontal wells. The experimental results demonstrate that fatigue acid fracturing effectively reduced the fracture pressure and weakened stress shadow effect. And the inclination degree is an influencing factor of fracture morphology complexity. The weathering zone and the calcite blocks had a noticeable impact on fracture propagation process. According to the experimental results, the fatigue acid fracturing will generate fresh insight into limestone formation stimulation treatments.

Multiple hydraulic fractures growth from a highly deviated well: A XFEM study

A fully coupled extended finite element (XFEM) model is presented to investigate the effect of different well types (highly deviated and horizontal wells) on simultaneous growth of multiple fractures. The importance of the use of deviated wells is briefly described and the governing equations for multi-cluster hydraulic fracturing in a saturated porous media are stated. The weak forms of both stress equilibrium and fluid mass continuity equations are turned into a system of linear equations through XFEM-type enrichments in space and Newmark scheme in time, which are solved by Newton-Raphson iteration method. In addition, the secant method is employed to impose the pressure continuity and mass conservation conditions at the fracture-well intersections. A numerical example with considering the simultaneous propagation of four hydraulic fractures is first adopted to validate the proposed numerical model. Several examples are then employed to investigate the influence of operational parameter, deviation angle, fracture spacing, placement and number on final fracture patterns. Numerical results show that coefficient of variation in multiple fracture heights for high-angle well is lower than that for horizontal well for all fracture placements. The opposite growth directions for two neighboring fractures, partially arising from the height difference at fracture-well intersection points, can reduce the stress shadow effect, thus promoting uniform growth of multiple fractures. Those results potentially unveil the causes for higher oil and gas production rates measured after multi-cluster hydraulic fracturing along highly deviated wells.

Shadow Effects of Superstars in Tennis

Shadow Effects of Superstars in Tennis

Improving Vegetation Segmentation with Shadow Effects Based on Double Input Networks Using Polarization Images

Improving Vegetation Segmentation with Shadow Effects Based on Double Input Networks Using Polarization Images

Polarized SERS substrates with directionality, repeatability and orderability: an anisotropic Ag nanocavity array

The anisotropic Ag nanocavity based on the shadow effect of the nanosphere array can effectively eliminate the background signals.

Modelling Building Shadows on Rooftop Generating 3D City Model

Abstract: 3D city models enable us to gain a better grasp of how various city components interact with one another. Advances in geosciences now allow for the automatic creation of high-quality, realistic 3D city models. It is not limited to visualization and navigation, however, also for shadow and solar potential analysis. Solar radiation is an example of a 3D GIS tool that is in high demand. The calculation of solar radiation that reaches 3D objects can be simple, but the shadow effect of nearby buildings is a considerably more challenging issue because some facades or roofs are only partially shadowed. The present study is analyzed into two approaches. The first approach is considered as Visualization (client-side) approach to visualize the 3D city models on the website using NodeJS and CesiumJS. The second approach is considered as Analyzation (Server-side) approach to analyze the solar potential using python for faster processing and deeming the future development aspects.

The scene as a space for artistic searches of the director-author. Part 1. Rainer Werner Fassbinder: stage-screen experiments

The purpose of the article is to identify the problems of creativity of directors who have realized their artistic potential both in auteur cinema and in the space of the stage and to determine scientific guidelines that will contribute to a comprehensive analysis of the phenomenon of the filmmaker in the performing arts. Research methodology. Methods of scientific analysis, comparison, generalization, self-analysis of the artist were used in the elaboration of the theme. In addition, analytical and systematic methods were applied in their unity, which is necessary to study the art aspect of the problem. The scientific novelty of the study is to determine the universality of directing as a specific kind of artistic and aesthetic activity; in clarifying the interaction of performing and screen arts in the use of expressive means; in determining the features of the filmmaker's activity in the stage space through the adaptation of screen means in theatrical productions, which first became the subject of a special study; in the coverage, the activities of directors-authors who resorted to reforming the language of language and the language of stage production; in identifying the original principles of filmmaking and specific means of cinematic expression, which not only found a direct embodiment in films and contributed to the emergence of outstanding authorial films but also had a significant impact on the author's theatrical direction, which sought to visualize stage images. Conclusions. It is proved that the stage work of filmmakers-authors calls into question the theoretical postulates about the perniciousness of the intrusion of theater culture into screen works. It has been found that pictorial and expressive means provide a chronology of image creation (long shots, in-frame editing, acoustic, light, and shadow effects), the use of which in cinema is considered a high degree of skill, have their origins in the performing arts. Keywords: director-author, stage space, directing means, theater, screen.

Morphology induced large magnetic anisotropy in obliquely grown nanostructured thin film on nanopatterned substrate

The artificial tailoring of magnetic anisotropy by manipulating surface and interface morphology is attracting widespread interest for its application in spintronic and magnetic memory devices. Here oblique angle deposition on a nanopatterned rippled substrate is presented as a novel route of inducing large in-plane uniaxial magnetic anisotropy (UMA) in magnetic thin films. For this purpose, Cobalt films and rippled SiO2 substrates have been taken as a model system for the present study. Here, nanopatterned substrates are prepared by low energy ion beam erosion (IBE), above which films are deposited obliquely along and normal to the ripple directions. A clear anisotropy in the growth behavior has been observed due to the inhomogeneous in-plane organization of adatoms in the form of columns. The increased shadowing effect in the films deposited obliquely normal to the direction of the ripple patterns causes preferential coalescence of the columns along the substrate ripples, resulting in stronger in-plane UMA in the film. This peculiarity in magnetic behavior is addressed by considering the morphological anisotropy governed by enhanced shadowing effect, the shape anisotropy and the dipolar interactions among the magnetostatically coupled ripple structure.

Acoustic invisibility cloak based on two-dimensional solid-fluid phononic crystals

In this paper, we present a cloaking structure based on two-dimensional phononic crystals and show the ability to hiding the object with any size and shape, which fit in the invisibility area, from the acoustic wave, that the operating frequency can be easily changed by changing dimensions of the unit cell and filling factor. The cooperation of two important features of phononic crystals including negative refraction and self-collimation enabled us to design the phononic structure for invisibility purposes. We will show that scattering from the object with the proposed cloak is minimized and the wave will be reconstructed behind the structure, so the shadow effect will also be reduced. In this article, we were able to hide an object from the detector by reducing the scattering, whether the detector is on the source side or on the opposite side.

Impact of geomechanical heterogeneity on multiple hydraulic fracture propagation

Abstract To extract more gas from shale gas reservoirs, the spacing among hydraulic fractures should be made smaller, resulting in a significant stress shadow effect. Most studies regarding the stress shadow effect are based on the assumption of homogeneity in rock properties. However, strong heterogeneity has been observed in shale reservoirs, and the results obtained with homogeneous models can be different from practical situations. A series of case studies have been conducted in this work to understand the effects of mechanical heterogeneity on multiple fracture propagation. Fracture propagation was simulated using the extended finite element method. A sequential Gaussian simulation was performed to generate a heterogeneous distribution of geomechanical properties. According to the simulation results, the difficulty of fracture propagation is negatively correlated with the Young's modulus and Poisson's ratio, and positively correlated with tensile strength. When each of the multiple fractures propagates in a homogeneous area with different mechanical properties, the final geometry of the fracture is similar to homogeneous conditions. When the rock parameter is a random field or heterogeneity perpendicular to the propagation direction of fracture, the fracture will no longer take the wellbore as the center of symmetry. Based on the analysis of fracture propagation in random fields, a small variance of elastic parameters can result in asymmetrical propagation of multiple fractures. Moreover, the asymmetrical propagation of hydraulic fractures is more sensitive to the heterogeneity of Poisson's ratio than Young's modulus. This study emphasises the importance of considering geomechanical heterogeneity and provides some meaningful suggestions regarding hydraulic fracturing designs.

A Novel Approach for Securing Nodes Using Two-Ray Model and Shadow Effects in Flying Ad-Hoc Network

In the last decades, flying ad-hoc networks (FANET) have provided unique features in the field of unmanned aerial vehicles (UAVs). This work intends to propose an efficient algorithm for secure load balancing in FANET. It is performed with the combination of the firefly algorithm and radio propagation model. To provide the optimal path and to improve the data communication of different nodes, two-ray and shadow fading models are used, which secured the multiple UAVs in some high-level applications. The performance analysis of the proposed efficient optimization technique is compared in terms of packet loss, throughput, end-to-end delay, and routing overhead. Simulation results showed that the secure firefly algorithm and radio propagation models demonstrated the least packet loss, maximum throughput, least delay, and least overhead compared with other existing techniques and models.

Accurate Simulations of the Reaction of H2 on a Curved Pt Crystal through Machine Learning.

Theoretical studies on molecule–metal surface reactions have so far been limited to small surface unit cells due to computational costs. Here, for the first time molecular dynamics simulations on very large surface unit cells at the level of density functional theory are performed, allowing a direct comparison to experiments performed on a curved crystal. Specifically, the reaction of D2 on a curved Pt crystal is investigated with a neural network potential (NNP). The developed NNP is also accurate for surface unit cells considerably larger than those that have been included in the training data, allowing dynamical simulations on very large surface unit cells that otherwise would have been intractable. Important and complex aspects of the reaction mechanism are discovered such as diffusion and a shadow effect of the step. Furthermore, conclusions from simulations on smaller surface unit cells cannot always be transfered to larger surface unit cells, limiting the applicability of theoretical studies of smaller surface unit cells to heterogeneous catalysts with small defect densities.

Effect of Stress Shadow Caused by Multistage Fracturing from Multiple Well Pads on Fracture Initiation and Near-Wellbore Propagation from Infill Wells

Summary Multistage fracturing with multiwell pads (MSFMP) is an essential technology for the efficient development of unconventional oil and gas reservoirs, but the reservoir area between two well pads is often not stimulated. Fracture initiation and near-wellbore propagation from infill horizontal wells drilled with different azimuth from the optimal azimuth in the unstimulated area is poorly understood, largely because of the stress shadow (or induced stress) caused by MSFMP. In this study, we propose an integrated method for calculating the stress shadow caused by MSFMP and then determine optimal completion parameters for infill horizontal wells in the unstimulated connecting area between two well pads. First, we develop a theoretical stress shadow model caused by MSFMP on the basis of the dislocation theory. Considering two extreme cases, fully open and completely closed propped fractures, the range of stress shadow in the unstimulated area after MSFMP of 20 horizontal wells in Platform H of tight reservoirs in the Changqing Oilfield, China, is considered as an example. Second, we import the calculated stress shadow into a 3D perforated fracturing model that is built based on the discrete lattice method. Then, we investigate the influence of perforation technology, horizontal wellbore azimuth, phase angle, and injection rate on fracture initiation and near-wellbore propagation. Our results show that this model is capable of calculating stress shadow at any position and then can be used to optimize the fracturing interval for the middle unstimulated area. We find that appropriate perforation and fracturing parameters significantly decrease the complexity of near-wellbore fractures. The models and results presented in this paper provide a new method and new insight for quantifying and optimizing fracture initiation and propagation for infill horizontal wells to maximize reservoir stimulation efficiency.

Influence of tower shadow on downwind flexible rotors: Field tests and simulations

AbstractAs wind turbine rotors become larger, the blades become more flexible, requiring extra stiffness and cost to avoid the risk of tower strike. Wind turbines in a downwind configuration have a reduced risk of tower strike because the rotor thrust acts away from the tower. However, downwind blades pass through the wake of the tower, and the resulting load variation may contribute to blade fatigue. To date, there have been no field tests to quantify this tower shadow effect on unsteady blade moments. The present study reports on the first field testing of a flexible, downwind, coned rotor and compares the experimental data against simulations run in OpenFAST. The tower shadow effect is simulated using the conventional Powles model and a new Eames model (developed herein), which includes the influence of upstream turbulence. Both models reasonably predict the blade root out‐of‐plane bending moment data and the tower shadow dip magnitude when compared to field test data in Region 3. Tower shadow was found to increase the short‐term Damage Equivalent Loads (DELs) by less than 10% compared to other effects (gravity, shear, and turbulence), and the predictions were consistent with experiments. These results indicate that the tower shadow effect can be reasonably modeled with the simpler Powles model and that the tower shadow effect can be small compared to the effect of turbulence. However, long‐term fatigue due to tower shadow should be included in detailed structural analysis and design of the rotor and the tower.

Late Pleistocene–Holocene climatic implications of high‐resolution stable isotope profiles of a speleothem from south‐central Anatolia, Turkey

ABSTRACTHigh‐resolution 230Th ages and stable isotope (δ18O and δ13C) records from a stalagmite that grew between 39 and 2 ka in Incesu Cave located in south‐central Anatolia allow us to evaluate paleoclimate conditions for growth periods during Marine Isotope Stage 3 (MIS3) and the Holocene. High δ18O values and Heinrich events H3 and H4 are observed during the MIS3 interval. After a dry period in the Younger Dryas, low values between ca. 10 and 5.3 ka suggest a transition to wet mid‐ to early Holocene conditions. In the early Holocene, there are drier periods at 9.4 and 10.3 ka, coincident with cooling events recorded in the North Atlantic sediments and, after 5.3 ka a relatively dry late Holocene is seen. The IN‐01 isotope record is in phase with general trends of speleothem records in Turkey and the Eastern Mediterranean but differs in detail at the millennial scale. The more depleted δ18O values of IN‐01 compared to those of Eastern Mediterranean speleothems during the Holocene indicate that central Anatolian winter rainfall was isotopically influenced by the same air mass trajectories derived from the North Atlantic and Mediterranean with an isotopic rain shadow effect.