Position Of Elements Research Articles

Legendre quadrature for the discretization of 1D radiating panels

AbstractIn [A. Capozzoli, C. Curcio, A. Liseno, MMS, Pizzo Calabro, Italy, 2022], the problem of modeling a source/scatterer using an equivalent radiator has been addressed and an approach has been given and numerically assessed.Once dimensioned the radiating panel, a practical implementation can be provided by a non-uniform array. The element positions should be chosen so that the array is capable to approximate, with an adequate accuracy, the fields radiated by the equivalent radiator. Here, the array element positioning is performed by exploiting a quadrature rule which takes into account that the singular functions supported on the region of interest associated to the most significant singular values of the radiation operator are related to those supported on the equivalent panel by a radiation integral. The quadrature rule enables also to choose a set of weights which are essential in the definition of the element excitation coefficients from the knowledge of the source distribution on the equivalent panel. For simplicity, a one-dimensional problem with a Legendre quadrature rule is considered. The approach is numerically assessed by checking the capability of the array to radiate, with a satisfactory degree of accuracy, the singular functions associated to the region of interest.

Способ построения двухэлементной цифровой антенной решетки для оценки угловых координат радиосигналов со сверхразрешением с повышенной точностью на основе нижней границы Крамер-Рао

In the paper an effective method for optimal placement of directional antenna elements for digital spatial signal estimation is discussed. The digital antenna array evaluates spatial coordinates with the subsequent beamforming. However, as it is well known, the relative position of antenna elements, their number and the shape of the radiation pattern have a significant impact on the quality of the spatial pseudospectrum. The paper uses the previously obtained expression for estimating the Cramer-Rao lower bound to reduce the number of antenna elements without losing the accuracy of direction-of-arrival estimation of the signals. For example, a two-element array is obtained. The elements have a flat-top radiation pattern. It is shown that the accuracy of the MUSIC method in the obtained array is higher or comparable to the array composed of three elements.

Triad-Displaced ULAs Configuration for Non-Circular Sources with Larger Continuous Virtual Aperture and Enhanced Degrees of Freedom

Non-uniform linear array (NULA) configurations are well renowned due to their structural ability for providing increased degrees of freedom (DOF) and wider array aperture than uniform linear arrays (ULAs). These characteristics play a significant role in improving the direction-of-arrival (DOA) estimation accuracy. However, most of the existing NULA geometries are primarily applicable to circular sources (CSs), while they limitedly improve the DOF and continuous virtual aperture for non-circular sources (NCSs). Toward this purpose, we present a triad-displaced ULAs (Tdis-ULAs) configuration for NCS. The Tdis-ULAs structure generally consists of three ULAs, which are appropriately placed. The proposed antenna array approach fully exploits the non-circular characteristics of the sources. Given the same number of elements, the Tdis-ULAs design achieves more DOF and larger hole-free co-array aperture than its sparse array competitors. Advantageously, the number of uniform DOF, optimal distribution of elements among the ULAs, and precise element positions are uniquely determined by the closed-form expressions. Moreover, the proposed array also produces a filled resulting co-array. Numerical simulations are conducted to show the performance advantages of the proposed Tdis-ULAs configuration over its counterpart designs.

Kritik Sosial Natsume Soseki dalam Novel Bocchan

This research aims to reveal Natsume Soseki's attitudes and views in the form of social criticism regarding the phenomenon of social deviation in Japanese society due to the Meiji Restoration (1868-1912) in his novel, Bocchan. Social problems often arise in modern societies, including what happened in Japan during modernization from 1868-1912, called the Meiji Restoration. These social problems include social and cultural dislocation due to the penetration of dominant Western culture and the marginal position of traditional elements, especially in the second decade of the early Meiji era, when Japan aggressively adopted Western culture on a large scale. This social phenomenon can be seen from the decline in Japanese society's appreciation for traditional social and cultural values while simultaneously placing Western culture in a superior position. The theory used in this research is Alan Swingewood's Literary Sociology theory. Through this theory, we will analyze the influence of Natsume Soseki's social background as the author of the novel Bocchan, as well as his ideological tendencies in responding to the symptoms of social deviation in Japanese society (1868-1912), which became the background for the creation of the novel Bocchan. After that, it will be analyzed to what extent the novel Bocchan can reflect social phenomena. The analysis was done by connecting the social aspects of the novel with the historical, social reality that was the background for its creation, namely Japanese society during the Meiji Era (1868-1912). Next, the author will see what social criticism is depicted in the novel. The results of the research show that the novel Bocchan describes Natsume Soseki's social criticism of the phenomenon of socio-cultural dislocation in Japanese society due to Westernization during the Meiji era, as well as the problems of a group of people who persist with old habits in the condition of the Japanese nation which is changing towards a developed and modern country.

Fatigue life and fatigue reliability mechanism of ball bearings

AbstractAs the main supporting parts of rotating machinery, the fatigue life and fatigue reliability of ball bearings directly affect the accuracy, stability and reliability of equipment. Based on the quasi-static model of bearing and the fatigue life theory, this paper analyzes the effect of the external loads on the mechanical properties and fatigue life of bearing, and studies the action mechanism of bearing working conditions and other parameters. In addition, based on the stress–strength model and the fatigue life model of bearing, the fatigue reliability and sensitivity of bearings are analyzed by means of perturbation method, Edgeworth series and fourth moment technique, and the correctness is verified by the Monte Carlo simulation. Results have important theoretical and practical value, and can provide theoretical support for the research of reliability optimization design, fault mechanism and fault diagnosis method of ball bearings.

A low-complexity DOA estimation algorithm using UAMP with Bernoulli-Gaussian prior

In this paper, we design a low-complexity direction-of-arrival (DOA) estimation algorithm based on the unitary approximate message passing (UAMP) and Bernoulli-Gaussian (BG) prior. We first show that the estimation of DOA can be transferred into a sparse signal recovery problem, where we turn to UAMP with damping technique to solve this problem. Furthermore, we assume the BG prior on the sparse vector to be estimated, resulting in the fast estimation of the positions of non-zero elements. Moreover, expectation maximum (EM) is leveraged to automatically learn the BG parameters. Compared to the state-of-the-art UAMP-based algorithm with sparse Bayesian learning (SBL), the proposed approach can achieve the same DOA mean square error (MSE) performance with a much faster convergence speed.

Stretching the Limits of MRI-Stretchable and Modular Coil Array Using Conductive Thread Technology.

We propose a modular stretchable coil design using conductive threads and commercially available embroidery machines. The coil design increases customizability of coil arrays for individual patients and each body part. Eight rectangular coils were constructed with custom-fabricated stretchable tinsel copper threads incorporated onto textile. Tune, match, and detune circuits were incorporated on the coil. A hook-and-loop mechanism was used to attach and decouple the modular coils. Phantom and in vivo scans at various anatomical flexion angles were acquired to highlight performance, and a temperature test was performed to verify safety. In vivo MRI experiments demonstrate high sensitivity and coverage of each anatomy. As the coils are stretched, the sensitive volume increases at a rate of 10.93 mL/cm2. The SNR reduction of a single coil was greater during compression than when stretched, but this did not affect image quality for the array. The modularity of the array allows for adaptability for any anatomy with simple on-demand adjustment to the number and position of coil elements. The images demonstrated high sensitivity and coverage of the stretchable array for various anatomies and flexion angles. Stretching the coils increases the sensitive volume, allowing for a larger region to be effectively imaged. The resonance shift and SNR decrease during stretch and compression support further investigation of methods to reduce frequency shift in stretchable coils. The proposed array design allows for highly stretchable, flexible, modular, and conformal patient-centered coils that allow for increased imaging quality, greater comfort, and rapid production.

Key role of subsurface doping in optimizing active sites of IrO2 for the oxygen evolution reaction.

The oxygen evolution reaction (OER) over a family of metal-doped rutile IrO2 catalysts is theoretically investigated by controlling the species and position of doped elements. The subsurface substitution doping is demonstrated to efficiently regulate the eg-filling of surface iridium sites and lower the adsorption strength of oxygen intermediates, improving the catalytic activity for the OER. Finally, based on screening, subsurface Cu- and Li-doped IrO2 models stand near the top of the volcano plot and display high levels of structural stability toward acidic OER.

Formation of reflective shells by electric arc spraying and application of composite material to the punch

In the course of the work, the process of forming reflective shells and finding the position of grid elements after deformation was investigated. Fixation of mesh nodes by electric arc spraying. After that, a composite material such as polystyrene is applied to form reflective shells. Minimization of potential energy is carried out numerically by an iterative method. The result of the work is the formation of the antenna array shell by the method of electric arc spraying and the application of the composite material. The following forming operations of sheet metal stamping are known: drawing, rotary drawing, relief forming, trimming, including rubber and liquid drawing, hydromechanical drawing, explosion drawing, electric discharge stamping, electromagnetic stamping, hydropneumatic drawing, which allow to obtain a shell from sheet material (solid or gas and water permeable) by pressing it against a die or punch with a transfer medium.

Additively manufactured structures for precise and robust mounting of optical elements

The design freedom of Additive Manufacturing offers new opportunities for the design of mounting structures of optical systems, which are not feasible for conventional manufacturing approaches, thus opening up new areas of application for optical systems. We use this to develop a fully monolithic mounting structure for precise positioning of the optical elements, while simultaneously increasing their robustness against harsh environmental conditions. We additively manufacture such a mounting structure for an imaging lens and evaluate its optical performance with interferometric measurement of its wavefront, before and after applying a mechanical shock to the entire system. The results indicate a centering accuracy better than 6 μm, both in the initial positioning as well as the subsequent repositioning after a mechanical shock of 15G.

Efficient calculation of the three-dimensional sound pressure field around a slab track

The wavenumber domain Boundary Element (2.5D BE) method is well suited to calculate the acoustic sound field around structures with a constant cross-section along one dimension, such as noise barriers or railway track. By expressing the sound field along this dimension in wavenumber domain, the numerical model is reduced from a 3D model to 2D model at each wavenumber. A consequence of the required discrete Fourier domain representation is that the sound field is represented by periodically repeating sections, of which only one section is physically meaningful. The resolution and the number of required wavenumbers increases with the desired length and spatial discretisation of this section. Describing the sound field adequately to auralise the sound without disturbing artefacts requires a large number of wavenumbers (and thus 2D BE computations), which is not feasible for large geometries. Here, a method is introduced that allows the calculation of the 3D sound field by solving a single 2D BE problem for a dense frequency spectrum and interpolating at higher wavenumbers. The calculation efficiency is further increased by precalculating the acoustic transfer functions between each BE surface element and receiver positions. Combining these two methods allows for efficient calculation of the 3D sound field around acoustically rigid structures such as slab tracks. The numerical approach is validated by comparison with a standard 2.5D BEM calculation and an analytical solution. Precalculated transfer functions to calculate the sound radiation from railway track, which are made available online, are illustrated. An example application is presented.

Ispitivanje nulte unakrsne korelacije fleksivilne promenljive težine (FVWZCC) za primenu u različitim medijima

Introduction/purpose: In this paper, we propose a novel code construction method with the zero cross-correlation property, the Flexible Variable Weight Zero Cross-Correlation (FVWZCC). This method is simple and flexible, using different code weights to support different classes of users according to their transmission distance and the quality of services they require (data, audio, and video) in OCDMA systems. The use of higher code weights enables the support of higher-priority application networks, such as long-haul reach networks. The ZCC code structure does not have overlapping of bit '1' and can efficiently eliminates the MAI interference between users and PIIN noise, thus enhancing the system overall performance. Methods: The shifting element position and the concatenation matrix process of the three basic matrices denoted as the Right vector, the basic matrix, and the Left vector were used for the construction of the proposed FVWZCC code. The mathematical analysis and simulations with Matlab and Optisystem software were used to evaluate the performance of the proposed FVWZCC method in SAC-OCDMA systems using the direct detection. Results: The results show a significant improvement in the presented code compared to other existing codes in terms of simplicity, flexibility, and cost implementation. The method uses either constant or variable weight with the Zero cross-correlation property. For a maximum acceptable BER of 10~9 , the simulation results of the SAC-OCDMA system using direct detection under OptiSystem software show better performance of the proposed code with four users of weight 6 at 10 Gb/s. Moreover, it can support up to 60 users simultaneously and reach a fibre distance of about 67 km. Consequently, the proposed FVWZCC code can be applied to support different Quality of Service (QOS) requirements with low cost and low complexity with a direct detection receiver. Conclusion: The findings of this study highlight the need for the FVWZCC code to support end-user QoS requirements. The new approach to code construction offers low-cost implementation, simplicity, and flexibility.

Planar antenna array synthesis for wireless power transmission based on brain storm optimization algorithm

AbstractThis study investigates the synthesis of a two‐dimensional transmitting planar antenna array for a wireless power transmission system. The antenna synthesis problem is transformed into an optimization problem under multiple constraints. Accordingly, a brainstorming optimization algorithm is utilized to optimize the element position of the planar antenna arrays under the constraints of aperture size, array spacing, and side lobe level. A numerical simulation of the beam collection efficiency is conducted under different receiving region shapes. The simulation results confirm the effectiveness of the proposed method in optimizing the two‐dimensional transmitting planar antenna array for wireless power transmission systems.

Evaluation of cranio-mandibular dysfunction in patients with dento-maxillary anomalies using the Helkimo index

Introduction. Dento-maxillary anomalies are characterized by changes in the size, shape, position and inclination of the morphological elements that make up the stomatognathic system. Recent studies demonstrate the fact that not only traumatic occlusion (OT) is the etiological factor of TMJ dysfunction. But muscular factors, vicious habits and dento-maxillary anomalies are also involved. Created by the Marti Helkimo in 1972 to investigate the prevalence and severity of signs and symptoms of temporomandibular dysfunction. Material and method. The study was carried out on a group of 78 patients from the personal case with various dento-maxillary anomalies and TMJ suffering. We statistically processed the data obtained from the clinical examination, in order to compare the situation of patients with temporomandibular dysfunction compared to that of patients without joint disorders at the time of the initial examination. Results. Most patients with class II/2 anomalies: 42.86% presented an anamnestic index of I, and a percentage of 20.69% had a Helkimo anamnestic index of II. So with this type of anomaly, the patients indicated obvious signs of ATM dysfunction. The Helkimo anamnestic index had the highest scores in the II/2 anomaly in the female sex, followed by class II/1 anomalies in the male gender. This index correlates better with the clinical one in the female for all types of anomalies. Conclusion. The most important examination in the case of TMJ pathology is represented by the thorough clinical examination. There is a directly proportional relationship between the degree of severity of the malocclusion and the Helkimo index points.

Computer-Assisted Modeling of Greater Tubercle Transposition Effect on Stress Distribution in Shoulder

Background. The aim of the work was to investigate the influence of the position of a fractured greater tubercle of the humerus on stress distribution in the glenohumeral joint (GHJ) at shoulder abduction by performing stress-strain analysis (SSA). Material and methods. A simulated 3D model of the shoulder was constructed on the basis of anatomical and anthropometric data as close as possible to real ones using the SolidWorks software package.Results. A finite-element model (FEM) was generated in a semi-automatic mode composed mostly of tetrahedral and hexagonal elements < 1 mm in dimensions.Conclusion. The simulated 3D model of the shoulder, based on anatomical and anthropometric data as close as possible to the real ones, makes possible highly accurate determination of the optimal mutual position of the movable elements of the real joint individually for each specific patient, and makes it possible to accurately perform a minimally invasive surgical operation.

Towards a corpus-based approach to graphic elements in creative subtitling

Abstract This article explores how a corpus-based approach allows us to describe and analyze the multimodal complexity of graphic elements in creative subtitling. To this end, the article focuses on a YouTube channel, Apenjie with Dawang, featuring a dog and its owner. This channel’s subtitling strategies were experimental with multiple graphic elements (colors, positions, font sizes, and emojis). Informed by a social semiotic approach to multimodality, a corpus of 1,155 coupled pairs of Chinese-English subtitles was annotated for modal shifts and metafunctional shifts. Some major findings include: (a) emojis were much more likely to be added to the target subtitles for the animals than for the humans; (b) speaker-identifying graphic elements (color and position) were lost in the target subtitles, but emojis were systematically added to mark animals as the speakers; (c) the addition of emojis evoked complementary-interpersonal meanings, suggesting that the subtitlers might have prioritized audience engagement over textual fidelity; (d) although the target subtitles used fewer graphic elements, the semiotic meanings could be similar or complementary to those of the source subtitles. Based on these findings, the article also discusses the opportunities and challenges of a corpus-based approach to graphic elements in creative subtitling.

A prophage encoded ribosomal RNA methyltransferase regulates the virulence of Shiga-toxin-producing Escherichia coli (STEC).

Shiga toxin (Stx) released by Shiga toxin producing Escherichia coli (STEC) causes life-threatening illness. Its production and release require induction of Stx-encoding prophage resident within the STEC genome. We identified two different STEC strains, PA2 and PA8, bearing Stx-encoding prophage whose sequences primarily differ by the position of an IS629 insertion element, yet differ in their abilities to kill eukaryotic cells and whose prophages differ in their spontaneous induction frequencies. The IS629 element in ϕPA2, disrupts an ORF predicted to encode a DNA adenine methyltransferase, whereas in ϕPA8, this element lies in an intergenic region. Introducing a plasmid expressing the methyltransferase gene product into ϕPA2 bearing-strains increases both the prophage spontaneous induction frequency and virulence to those exhibited by ϕPA8 bearing-strains. However, a plasmid bearing mutations predicted to disrupt the putative active site of the methyltransferase does not complement either of these defects. When complexed with a second protein, the methyltransferase holoenzyme preferentially uses 16S rRNA as a substrate. The second subunit is responsible for directing the preferential methylation of rRNA. Together these findings reveal a previously unrecognized role for rRNA methylation in regulating induction of Stx-encoding prophage.

Virtual planning for mandible resection and reconstruction

Abstract In mandibular reconstruction, computer-assisted procedures, including virtual surgical planning (VSP) and additive manufacturing (AM), have become an integral part of routine clinical practice. Especially complex cases with extensive defects after ablative tumor surgery benefit from a computer-assisted approach. Various CAD/CAM-manufactured tools such as surgical guides (guides for osteotomy, resection and predrilling) support the transition from virtual planning to surgery. Patient-specific implants (PSIs) are of particular value as they facilitate both osteosynthesis and the positioning of bone elements. Computer-based approaches may be associated with higher accuracy, efficiency, and superior patient outcomes. However, certain limitations should be considered, such as additional costs or restricted availability. In the future, automation of the planning process and augmented reality techniques, as well as MRI as a non-ionizing imaging modality, have the potential to further improve the digital workflow.

Regarding the resilience of market entities on the example of enterprises in the extractive industry

The last period (starting with the pandemic) cataclysms determined the importance for the macro- and microeconomies resilience as the ability of ecosystems, business, society to cope with shocks and continue to function in approximately the same way. The topic of resilience is extremely important for mining companies, because they cannot afford any relocation and industrial repurposing. The goal of this work is to clarify the essence of resilience and identify the factors that determine it for subjects of the market system. Research methods: general scientific – abstraction, analysis, synthesis, observation, generalization; the microcosm-system approach, which is an extension of the world-system approach to microeconomics; cumulative cost curves; single-factor production functions; methods of mathematical and statistical analysis; Zipf-Pareto law. The base of observations is the global coking coal market, production and economic indicators of the Ukrainian iron ore mining company. It is shown that the unprofitability of industrial and commercial activity is a necessary but not sufficient condition for the microcosm-economy to lose resilience. The loss of resilience is a process whose active actors, along with the direct subjects of the market, are their owners, the state and other subjects and authorities. The final stage of resilience loss occurs after the market subject crosses a certain point of no return. A model of a certain market is a cumulative cost curve. The final part of the cumulative cost curve`s graph, where the elements with the worst economic characteristics (high-risk group) are located, is significantly non-linear. The rank of the element position on the curve mathematically determines with the Zipf-Pareto law the cost value and identify the zone of market entities profitable functioning according with the market price of products. The application of the logit-regression model makes it possible to estimate the probability of a market subject's profitability loss at its inherent cost and the confidence interval of prices observed during a certain period. The risk degree of resilience loss is determined not only by the factors of the market itself, but also by the production function characteristic of the subject of market activity. The article provides an example of a one-factor logarithmic production function of a Ukrainian iron ore mining company.

Synthesis of Large Ultra-wideband Sparse Circular Planar Arrays Based on Rotationally Symmetric Structure

This article aims to improve the synthesis efficiency and radiation performance of large ultra-wideband (UWB) rotationally symmetric sparse circular planar arrays by using a modified differential evolution algorithm (MDEA). In the proposed MDEA, we adopt a new encoding mechanism in which an individual represents an element position expressed in polar coordinates. Importantly, such an encoding mechanism can facilitate the multiplication calculation for the array factor in the individual being updated while making it easier to meet the given minimum element spacing constraint. Moreover, to cater to the new encoding mechanism, some low-dimensional evolution operators are introduced to avoid the prematurity. In particular, the UWB rotationally symmetric sparse planar array synthesis problem is transformed into the sidelobe suppression problem of the array pattern at the highest frequency under the given array aperture, and the minimum spacing constraints is used to guarantee enough space to place physical UWB antenna elements. Two synthesis examples of UWB sparse planar arrays based on rotationally symmetric structures are presented. The results show that the peak sidelobe level (PSL) obtained by the proposed MDEA is significantly lower than the results obtained by some existing algorithms in an acceptable CPU time, which proves the effectiveness and superiority of the proposed MDEA.