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1
Kumar, V., und S. K. Dhull. „Genetic Algorithm based Optimization of Uniform Circular Array“. Engineering, Technology & Applied Science Research 10, Nr. 6 (20.12.2020): 6403–9. http://dx.doi.org/10.48084/etasr.3792.
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Signal estimation at the antenna is a major challenge of the antenna array structure because the received signals have different directions. Therefore, in this paper, a Genetic Algorithm (GA) is applied to the uniform circular array for the optimization of array structure in regard to its geometry. On the optimized array structure, four different algorithms (Estimation of Signal Parameter via Rotational Invariance Technique – ESPRIT, First Order Forward Prediction - FOFP, Beamscan, and Multiple Signal Classification - MUSIC) have been implemented in order to estimate the signal direction accurately with quick estimation time. The accuracy has been calculated with Root Mean Square Error (RMSE) indices. From the experimental analysis, it has been found that the performance of the ESPRIT algorithm is better than the others in terms of accuracy and estimation time.
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Bludov, A. A., G. A. Gorbatovskij, V. S. Pavlov und A. F. Suvorov. „Estimation and Adjustment of Polarization Errors in Conical Scan Method“. Journal of the Russian Universities. Radioelectronics, Nr. 2 (05.06.2018): 47–54. http://dx.doi.org/10.32603/1993-8985-2018-21-2-47-54.
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The article proposes a solution of a problem of polarization error compensation for radar object direction finding by means of conical scan method. The solution is considered at signal processing level that makes possible to avoid polarization limitations in antennas engineering. The purpose of the article is to substantiate a model for polarization-induced errors by conical scan direction finding method and to develop an algorithmic technique for the considered method correction with regard to arbitrary polarization conditions of radar interaction. The results are presented by analytical model along with quantitative estimates of polarization-induced errors of direction finding and the computational procedure of the error compensation as well as by analysis of imperfectness factors for the proposed procedure exposing its practical applicability.
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He, Jiazhi, Zhen Huang und Xuefeng Feng. „A High-Precision Algorithm for DOA Estimation Using a Long-Baseline Array Based on the Hearing Mechanism of the Ormia Ochracea“. Sensors 22, Nr. 3 (07.02.2022): 1249. http://dx.doi.org/10.3390/s22031249.
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Inspired by the Ormia Ochracea hearing mechanism, a new direction of arrival estimation using multiple antenna arrays has been considered in spatially colored noise fields. This parasitoid insect can locate s cricket’s position accurately using the small distance between its ears, far beyond the standard array with the same aperture. This phenomenon can be understood as a mechanical coupled structure existing between the Ormia ears. The amplitude and phase differences between the received signals are amplified by the mechanical coupling, which is functionally equivalent to a longer baseline. In this paper, we regard this coupled structure as a multi-input multi-output filter, where coupling exists between each pair of array elements. Then, an iterative direction-finding algorithm based on fourth-order cumulants with fully coupled array is presented. In this manner, the orientation of the mainlobe can direct at the incident angle. Hence, the direction-finding accuracy can be improved in all possible incident angles. We derive the Cramér-Rao lower bound for our proposed algorithm and validate its performance based on simulations. Our proposed DOA estimation algorithm is superior to the existing biologically inspired direction-finding and fourth-order cumulants-based estimation algorithms.
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Wu, Tao, Zhenghong Deng, Jiwei Xu und Qingyue Gu. „Estimation for Two-Dimensional Incoherently Distributed Source in Double L-Shape Arrays“. Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 37, Nr. 4 (August 2019): 838–45. http://dx.doi.org/10.1051/jnwpu/20193740838.
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Distributed sources can be regarded as an assembly of point sources within a spatial distribution. In this paper, we explore the estimation of the two-dimensional incoherently distributed sources using double L-shape arrays. The rotational invariance properties of the nominal elevation and nominal elevation are firstly obtained by taking first-order Taylor series expansions with regard to the generalized steering vectors of two pairs of parallel subarrays. The rotation operators can be solved based on signal subspace. Then the nominal elevation and nominal elevation can be obtained from parameters matching method. Estimation of direction of arrival can be used in multi-source scenario and needn't peak-finding search. Lastly the angular spreads can be solved through two-dimensional Capon search based on nominal angles. The simulation experiments show that the proposed method has good performance on the estimation of two-dimensional incoherently distributed sources. Investigating different experimental conditions, sources with different angular spreads, simulations are conducted to validate better estimation accuracy of the proposed method.
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Ezazshahabi, Nazanin, Masoud Latifi und Mohammad Amani Tehran. „Analysis of Frictional Behavior of Woven Fabrics by a Multi-directional Tactile Sensing Mechanism“. Journal of Engineered Fibers and Fabrics 10, Nr. 3 (September 2015): 155892501501000. http://dx.doi.org/10.1177/155892501501000307.
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The frictional property of woven fabrics is one of the prominent surface characteristics which influence the performance of fabrics in a variety of applications. In this paper a novel methodology and instrument is proposed to measure the tactile force between fabric and simulated skin in different directions, and the obtained data are used for assessing fabric frictional property. In this regard, nine groups of woven fabrics consisting of three weave structures and three different weft densities were tested. By fitting the data with a proper equation, the tactile force in terms of fabric direction was predicted. The mentioned equation is also utilized for estimation of frictional behavior of fabric in various directions. Moreover, a single, new parameter called “frictional energy” is defined which has the ability to properly quantify the fabric frictional behavior. Statistical analysis of results reveals that the effect of weave structure and weft density is significant on the fabric friction. Being aware of the effect of fabric construction on friction is a guide for selecting the suitable fabric for various end uses.
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Saruchi, Sarah ‘Atifah, Mohd Hatta Mohammed Ariff, Hairi Zamzuri, Noor Hafizah Amer, Nurbaiti Wahid, Nurhaffizah Hassan und Khairil Anwar Abu Kassim. „Novel Motion Sickness Minimization Control via Fuzzy-PID Controller for Autonomous Vehicle“. Applied Sciences 10, Nr. 14 (10.07.2020): 4769. http://dx.doi.org/10.3390/app10144769.
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In terms of vehicle dynamics, motion sickness (MS) occurs because of the large lateral acceleration produced by inappropriate wheel turning. In terms of passenger behavior, subjects experience MS because they normally tilt their heads towards the direction of lateral acceleration. Relating these viewpoints, the increment of MS originates from the large lateral acceleration produced by the inappropriate wheel’s turn, which then causes greater head movement with respect to the lateral acceleration direction. Therefore, this study proposes the utilization of fuzzy-proportional integral derivative (PID) controller for an MS minimization control structure, where the interaction of the lateral acceleration and head tilt concept is adopted to diminish the lateral acceleration. Here, the head movement is used as the controlled variable to compute the corrective wheel angle. The estimation of the head movement is carried out by an estimation model developed by the radial basis function neural network (RBFNN) method. An experiment involving a driving simulator was conducted, to verify the proposed control system’s performance in regard to the autonomous vehicle’s passengers. The results show that the averages of motion sickness incidence (MSI) index can be lowered by 3.95% for single lap and 11.49% for ten laps.
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Shibu, Damodaran Santhamani, Soman Latha Nitin, Christophe Chesneau, Muhammed Rasheed Irshad, Sobhanam Padmini Shibin und Radhakumari Maya. „On the Hybrid Normal Distribution and Its Application in Fiber Data on the Strength of Glass“. Dynamics 2, Nr. 4 (18.11.2022): 399–413. http://dx.doi.org/10.3390/dynamics2040023.
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The hybrid normal (HN) distribution is a new generalization of the normal distribution that we introduce and study in this article. Its mathematical foundation is based on the logarithmically transformed version of the famous hybrid log-normal (HLN) distribution, which is an unexplored direction in the literature. We emphasize the applicability of the HN distribution with the aim of fitting versatile data, such as, in this paper, fiber data on the strength of glass. In particular, the unknown parameters are estimated using both Bayesian and maximum likelihood estimation approaches, with Bayesian estimation carried out using the MCMC approach. A thorough simulation study is performed to determine the flexibility of the estimates’ performance. The glass fiber data are then analyzed, with an assessment of several existing distributions from the literature used to demonstrate how the HN distribution is relevant in this regard.
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Ukleja, Janusz. „Stability estimation of slopes with determined slip surface by the MSTAB-3D method based on sliding body limit equilibrium analysis“. MATEC Web of Conferences 262 (2019): 04004. http://dx.doi.org/10.1051/matecconf/201926204004.
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The method developed for this study, established on the premises of the limit equilibrium flat analysis for a spatial solution, is a modification of the STAB-3D method, previously described by the author. It combines the analyses methods of 2D slices of flat cross–sections with the spatial analyses methodology rooted in a specific breakdown of a landslide sliding body into 3D elements assuming some simplifying solution. However, this method is solely applicable in case of a landslide failure with a stipulated slip surface and with a consistent decline of a determined slide direction. Such a method was developed in the article published earlier, which provided then its basic assumptions and the equilibrium formulations. The following publication thereof, presents overall suppositions for this method as well as its modification involving the resultant forces brought to the equilibrium with the generalized slide direction. Apart from that, a comparative analysis was carried out on the impact of this modification applicability of the obtained results with regard to the STAB-3D method. The algorithm was also presented concerning the modified method with its results being compared to a couple of selected methods LEM (limit equilibrium method). The undertaken analysis reveals that the modified MSTAB-3D method determines stability indicators that are very similar to its earlier version. Moreover, the results occur to be also approximating the values obtained in the course of other methods with regard to the flat cross-section analysis.
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Glazkov, A. A., A. V. Kuznetsov, V. A. Kuznetsov, M. A. Gurkina und L. Yu Kostina. „EXPERIMENTAL ESTIMATION OF THE OPTIMAL INTERVAL BETWEEN STITCHES OF AN ONE-ROW INTESTINAL SUTURE WITH REGARD TO TIGHTNESS“. Sibirskij medicinskij vestnik 6, Nr. 3 (2022): 29–34. http://dx.doi.org/10.31549/2541-8289-2022-6-3-29-34.
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Mastery of the intestine suture skills is one of the main competencies of a surgeon. Most of the available know¬ledge on the technical implementation of the intestinal suture is empirical, obtained over the years of the a¬uthor's practice, and transferred by him to the pages of his written work. In this regard, the study of such technical aspects of the implementation of an one-row intestinal suture is an important direction. The aim of the research is to perform a comparative evaluation of one-row extramucosal intestinal anastomoses realized with different stitch spacing. The study was carried out on preparations of the porcine small intestine after the formation of an one-row extramucosal intestinal anastomosis with different intervals between stitches. After that, an estimation of the tightness, execution time and number of stitches between study groups, was performed. The tightness was assessed by making a hydraulic test to determine the leakage pressure – the intraluminal pressure at which leakage occurred through the suture line. In the course of the study, the optimal interval between stitches was determined when applying an one-row intestinal anastomosis formed on the porcine small intestine.
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Shkrabak, Roman Vladimirovich. „Estimation of the performance of automotive engines by the results of their diagnosis under operating conditions“. Agrarian Scientific Journal, Nr. 3 (28.03.2022): 103–6. http://dx.doi.org/10.28983/asj.y2022i3pp103-106.
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The need for food supply for the population has been and remains the most important component of the life of the world's population. In connection with the growth of the population, this need will grow. Considering that food production requires enormous and constant work in the bosom of the Earth's biosphere, measures are being taken to alleviate working conditions, increase its efficiency, safety and efficiency. In this regard, the growth of electromechanization and automation of technological processes in the agro-industrial complex is an inevitability not only of the past, but also of the current century. With regard to agricultural production, the decisive factor in this direction is the use of mobile agricultural units with piston motor tractor engines. The latter are characterized by the peculiarity of reducing efficiency as they approach the amortization period, up to complete failure (i.e., termination of performance). In this regard, specialists are developing methods and tools for diagnosing the operability of auto-tractor engines in order to restore it in a timely manner. For this purpose, an innovative device has been proposed for diagnosing the operability of these engines. The article provides a diagram of the device, a description of the principle of its operation to achieve the set goal under operating conditions. The constituent structural elements of the device are deficient-free and affordable. The device combined with their use is not structurally difficult and allows one to obtain reliable results on assessing the performance of engines according to their measured characteristic indicators under operating conditions.
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Shkrabak, Roman Vladimirovich. „Estimation of the performance of automotive engines by the results of their diagnosis under operating conditions“. Agrarian Scientific Journal, Nr. 3 (28.03.2022): 103–6. http://dx.doi.org/10.28983/asj.y2022i3pp103-106.
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The need for food supply for the population has been and remains the most important component of the life of the world's population. In connection with the growth of the population, this need will grow. Considering that food production requires enormous and constant work in the bosom of the Earth's biosphere, measures are being taken to alleviate working conditions, increase its efficiency, safety and efficiency. In this regard, the growth of electromechanization and automation of technological processes in the agro-industrial complex is an inevitability not only of the past, but also of the current century. With regard to agricultural production, the decisive factor in this direction is the use of mobile agricultural units with piston motor tractor engines. The latter are characterized by the peculiarity of reducing efficiency as they approach the amortization period, up to complete failure (i.e., termination of performance). In this regard, specialists are developing methods and tools for diagnosing the operability of auto-tractor engines in order to restore it in a timely manner. For this purpose, an innovative device has been proposed for diagnosing the operability of these engines. The article provides a diagram of the device, a description of the principle of its operation to achieve the set goal under operating conditions. The constituent structural elements of the device are deficient-free and affordable. The device combined with their use is not structurally difficult and allows one to obtain reliable results on assessing the performance of engines according to their measured characteristic indicators under operating conditions.
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Shkrabak, Roman Vladimirovich. „Estimation of the performance of automotive engines by the results of their diagnosis under operating conditions“. Agrarian Scientific Journal, Nr. 3 (28.03.2022): 103–6. http://dx.doi.org/10.28983/asj.y2022i3pp103-106.
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The need for food supply for the population has been and remains the most important component of the life of the world's population. In connection with the growth of the population, this need will grow. Considering that food production requires enormous and constant work in the bosom of the Earth's biosphere, measures are being taken to alleviate working conditions, increase its efficiency, safety and efficiency. In this regard, the growth of electromechanization and automation of technological processes in the agro-industrial complex is an inevitability not only of the past, but also of the current century. With regard to agricultural production, the decisive factor in this direction is the use of mobile agricultural units with piston motor tractor engines. The latter are characterized by the peculiarity of reducing efficiency as they approach the amortization period, up to complete failure (i.e., termination of performance). In this regard, specialists are developing methods and tools for diagnosing the operability of auto-tractor engines in order to restore it in a timely manner. For this purpose, an innovative device has been proposed for diagnosing the operability of these engines. The article provides a diagram of the device, a description of the principle of its operation to achieve the set goal under operating conditions. The constituent structural elements of the device are deficient-free and affordable. The device combined with their use is not structurally difficult and allows one to obtain reliable results on assessing the performance of engines according to their measured characteristic indicators under operating conditions.
13
Wu, Tao, Zhenghong Deng, Yiwen Li und Yijie Huang. „Two-Dimensional DOA Estimation for Incoherently Distributed Sources with Uniform Rectangular Arrays“. Sensors 18, Nr. 11 (23.10.2018): 3600. http://dx.doi.org/10.3390/s18113600.
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Aiming at the two-dimensional (2D) incoherently distributed (ID) sources, we explore a direction-of-arrival (DOA) estimation algorithm based on uniform rectangular arrays (URA). By means of Taylor series expansion of steering vector, rotational invariance relations with regard to nominal azimuth and nominal elevation between subarrays are deduced under the assumption of small angular spreads and small sensors distance firstly; then received signal vectors can be described by generalized steering matrices and generalized signal vectors; thus, an estimation of signal parameters via rotational invariance techniques (ESPRIT) like algorithm is proposed to estimate nominal elevation and nominal azimuth respectively using covariance matrices of constructed subarrays. Angle matching method is proposed by virtue of Capon principle lastly. The proposed method can estimate multiple 2D ID sources without spectral searching and without information of angular power distribution function of sources. Investigating different SNR, sources with different angular power density functions, sources in boundary region, distance between sensors and number of sources, simulations are conducted to investigate the effectiveness of the proposed method.
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Arroyo, Felipe N., Jéssica F. Borges, Wanderlei M. Pereira Junior, Herisson F. Santos, Ivanildo A. Oliveira, Túlio H. Panzera, André L. Christoforo und Francisco A. R. Lahr. „Estimation of Flexural Tensile Strength as a Function of Shear of Timber Structures“. Forests 14, Nr. 8 (29.07.2023): 1552. http://dx.doi.org/10.3390/f14081552.
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To avoid the intrinsic difficulties regarding the characterization of wood (i.e., different applications in different directions), various normative documents present the relationships between properties; the Brazilian standard is of particular interest in this regard, because Brazil has a huge diversity of tree species from tropical forests, usually used in construction. In view of this, this research aimed to propose a new list of properties to be inserted in future versions of the Brazilian standards in order to help identify the species shear strength. It is expected that there is a correlation between the characteristic values of flexural strength (fm,k) and shear strength in the direction parallel to the wood fibers (fv,0,k), leading to models that make it possible to estimate one of the properties if the other is known, which was the main objective of this research. After finding a strong correlation between the properties, various regression models were evaluated. It can be concluded that the linear model composed only by the angular coefficient (equation with only one variable) presented a determination coefficient of 76.45%, which shows the good precision achieved in the estimation of one of the two variables compared if the other is known. Additionally, an attempt was made to define which probability distribution represents the resistance data by applying maximum likelihood (MLE), concluding that there is little difference between the representation by the normal distribution and the generalized extreme value (GEV) distribution. Another approach was to define the undermining coefficient to ensure the reliability of the prediction equation by the experiment-based calibration methodology defined by Eurocode.
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Nassiri, Habibollah, Ali Edrissi und Hamed Alibabai. „ESTIMATION OF THE LOGIT MODEL FOR THE ONLINE CONTRAFLOW PROBLEM“. TRANSPORT 25, Nr. 4 (31.12.2010): 433–41. http://dx.doi.org/10.3846/transport.2010.53.
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Contraflow or lane reversal is an efficient way for increasing the outbound capacity of a network by reversing the direction of in‐bound roads during evacuations. Hence, it can be considered as a potential remedy for solving congestion problems during evacuation in the context of homeland security, natural disasters and urban evacuations, especially in response to an expected disaster. Most of the contraflow studies are performed offline, thus strategies are generated beforehand for future implementation. Online contraflow models, however, would be often computationally demanding and time‐consuming. This study contributes to the state of the art of contraflow modelling in two regards. First, it focuses on the calibration of a Logit choice model which predicts the online contraflow directions of strategic lanes based on the set of directions obtained from offline scenarios. This is the first effort to adjust offline results to be applied for an online case. The second contribution of this paper is the generation of calibration data set from a novel approach through simulation. The calibrated Logit model is then tested for the network of the City of Fort Worth, Texas. The results show a high performance of this approach to generating beneficial strategies, including an increase in up to 16% in throughput compared to no contraflow case.
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Susaki, J., N. Maeda und S. Akatsuka. „ESTIMATION OF PHASE DELAY DUE TO PRECIPITABLE WATER FOR DINSARBASED LAND DEFORMATION MONITORING“. ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences IV-2/W4 (14.09.2017): 477–84. http://dx.doi.org/10.5194/isprs-annals-iv-2-w4-477-2017.
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In this paper, we present a method for using the estimated precipitable water (PW) to mitigate atmospheric phase delay in order to improve the accuracy of land-deformation assessment with differential interferometric synthetic aperture radar (DInSAR). The phase difference obtained from multi-temporal synthetic aperture radar images contains errors of several types, and the atmospheric phase delay can be an obstacle to estimating surface subsidence. In this study, we calculate PW from external meteorological data. Firstly, we interpolate the data with regard to their spatial and temporal resolutions. Then, assuming a range direction between a target pixel and the sensor, we derive the cumulative amount of differential PW at the height of the slant range vector at pixels along that direction. The atmospheric phase delay of each interferogram is acquired by taking a residual after a preliminary determination of the linear deformation velocity and digital elevation model (DEM) error, and by applying high-pass temporal and low-pass spatial filters. Next, we estimate a regression model that connects the cumulative amount of PW and the atmospheric phase delay. Finally, we subtract the contribution of the atmospheric phase delay from the phase difference of the interferogram, and determine the linear deformation velocity and DEM error. The experimental results show a consistent relationship between the cumulative amount of differential PW and the atmospheric phase delay. An improvement in land-deformation accuracy is observed at a point at which the deformation is relatively large. Although further investigation is necessary, we conclude at this stage that the proposed approach has the potential to improve the accuracy of the DInSAR technique.
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Li, Yang, Jia Yu und Liyuan He. „TOA and DOA Estimation for IR-UWB Signals: An Efficient Algorithm by Improved Root-MUSIC“. Wireless Communications and Mobile Computing 2021 (01.05.2021): 1–10. http://dx.doi.org/10.1155/2021/9960273.
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The automatically paired time of arrival (TOA) and direction of arrival (DOA) can be jointly estimated via a high-precision multidimensional spectral peak search- (SPS-) based multiple signal classification (MUSIC) algorithm in the impulse radio ultrawideband (IR-UWB) positioning system, while heavy computational burden is required. To tackle this issue, we propose an improved root-MUSIC algorithm for joint TOA and DOA estimation. After modelling the frequency domain form of the received signal, the algorithm first uses the signal subspace to establish the relationship between the two antennas. Then, the MUSIC spatial spectrum function is reconstructed with this relation, which enables it to offer a spectrum function in regard to the one-dimensional (1D) parameter of time delay. For further reducing the complexity, the TOA estimates of one antenna are obtained via 1D polynomial root finding instead of SPS, and the TOA estimates of the other antenna can be calculated by the established relationship. Finally, the DOA estimation can be achieved with the estimated TOAs. Due to the relationship between two antennas with signal subspace, the parameters estimated by the proposed algorithm are autopaired. Numerical simulations substantiate the superiority of the proposed algorithm.
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Galushko, V., O. Vlasenko und Y. Bulakh. „ANALYSIS OF DUAL-FREQUENCY INTERFEROMETRY APPLICABILITY FOR TARGET ELEVATION ANGLE MEASUREMENT USING TWO-COORDINATE RADARS“. RADIO PHYSICS AND RADIO ASTRONOMY 28, Nr. 2 (2023): 143–57. http://dx.doi.org/10.15407/rpra28.02.143.
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Subject and Purpose. The study deals with the dual-frequency radio interferometry technique, which is based on the employment of two fairly close frequencies with the aim to remove ambiguity of the radar target elevation estimation using 2D-radar and eliminate 2 pm-uncertainty of the signal phase difference measurement. Analysis of random noise action on the accuracy of the elevation angle estimation by the dual-frequency radio interferometry and assessment of practical applicability of the method make up the purpose of the paper. Methods and Methodology. The noise action on the elevation angle measurement accuracy is examined through a series of an- alytical calculations with the use of statistical analysis methods. The noise in each receiving channel is modeled in terms of additive, statistically independent stationary Gaussian processes with zero mean values and equal variances. The calculation results are checked via computer simulations with statistics estimations for 106 random noise realizations. Results. A correct condition has been developed for the sector width where the target elevation angle is unambiguously estimated depending on the space separation of the antennas (baselines) and the frequency ratio. Expressions for elevation angle estimation errors have been obtained, showing that the error is mainly contributed by the faults in the determination of the ambiguity interval number. A probability of the correct determination of the ambiguity interval number has been derived depending on the signal- to-noise ratio and the frequency difference, indicating that almost one hundred per cent probability of the correct determination of the ambiguity interval number is only achieved when the signal-to-noise ratio exceeds 30 dB. A comparative analysis has been performed between the methods of dual-frequency interferometry and conventional phase-difference direction finding in the case of close X-band frequencies and the same sectors of survey. Conclusions. The dual-frequency radio interferometry technique with close frequencies has been shown to outperform the stand- ard phase-difference direction-finding method only when the signal-to-noise ratio is sufficiently high (over 30 dB). In principle, the accuracy of the technique seems possible to improve by taking significantly different frequencies selected with regard to the scale negotiation condition. However, it should be mentioned that the implementation of the relevant algorithm in practice is much more complicated than the conventional scheme with a single frequency and several antenna baselines.
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Honda, Kazuhiro, Kosuke Takakura und Yuki Otsubo. „Smart Gateway for Healthcare Networks Based on Beam Steering Technology“. Sensors 23, Nr. 6 (09.03.2023): 2959. http://dx.doi.org/10.3390/s23062959.
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To ensure high-reliability communication in healthcare networks, this paper presents a smart gateway system that includes an angle-of-arrival (AOA) estimation and a beam steering function for a small circular antenna array. To form a beam toward healthcare sensors, the proposed antenna estimates the direction of the sensors utilizing the radio-frequency-based interferometric monopulse technique. The fabricated antenna was assessed based on the measurements of complex directivity and the over-the-air (OTA) testing in Rice propagation environments using a two-dimensional fading emulator. The measurement results reveal that the accuracy of the AOA estimation agrees well with that of the analytical data obtained through the Monte Carlo simulation. This antenna is embedded with a beam steering function employing phased array technology, which can form a beam spaced at 45° intervals. The ability of full-azimuth beam steering with regard to the proposed antenna was evaluated by beam propagation experiments using a human phantom in an indoor environment. The received signal of the proposed antenna with beam steering increases more than that of a conventional dipole antenna, confirming that the developed antenna has great potential of achieving high-reliability communication in a healthcare network.
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Клычова, Гузалия, Guzaliya Klychova, Алсу Закирова, Alsu Zakirova, Альфия Юсупова, Al'fiya Yusupova, Айгуль Клычова und Augul Klychova. „THE MAIN DIRECTIONS OF ESTIMATION OF CORPORATE SOCIAL RESPONSIBILITY OF BUSINESS“. Vestnik of Kazan State Agrarian University 13, Nr. 3 (07.11.2018): 130–34. http://dx.doi.org/10.12737/article_5bcf579e4860c0.23941805.
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In modern conditions, the social component of business is becoming increasingly important both for organizations and for society as a whole, since, as many years of experience show, those enterprises that develop their socially-oriented activities are more trusted by the state, investors, counterparties, creditors and other business partners. The social responsibility of business helps minimize the negative impact of the enterprise's production activities, the formation of an atmosphere of trust, predictability and common values in society, thanks to which, business becomes economically and socially more sustainable. In this regard, relevant issues are related to the assessment of the level of social responsibility of the enterprise, determining the main directions of social development of companies. The economic essence of the concept “corporate social responsibility” has been studied and specified in the article, the main directions of the corporate social responsibility of business assessment are examined. For a comprehensive assessment of corporate social responsibility, a system of indicators is proposed that takes into account its following components: the development and implementation of human resources, the formation of environmental sustainability and the implementation of socially significant projects.
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Luo, Jiawei, Yongwei Zhang, Jianyu Yang, Donghui Zhang, Yongchao Zhang, Yin Zhang, Yulin Huang und Andreas Jakobsson. „Online Sparse DOA Estimation Based on Sub–Aperture Recursive LASSO for TDM–MIMO Radar“. Remote Sensing 14, Nr. 9 (29.04.2022): 2133. http://dx.doi.org/10.3390/rs14092133.
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The least absolute shrinkage and selection operator (LASSO) algorithm is a promising method for sparse source location in time–division multiplexing (TDM) multiple–input, multiple–output (MIMO) radar systems, with notable performance gains in regard to resolution enhancement and side lobe suppression. However, the current batch LASSO algorithm suffers from high–computational complexity when dealing with massive TDM–MIMO observations, due to high–dimensional matrix operations and the large number of iterations. In this paper, an online LASSO method is proposed for efficient direction–of–arrival (DOA) estimation of the TDM–MIMO radar based on the receiving features of the sub–aperture data blocks. This method recursively refines the location parameters for each receive (RX) block observation that becomes available sequentially in time. Compared with the conventional batch LASSO method, the proposed online DOA method makes full use of the TDM–MIMO reception time to improve the real–time performance. Additionally, it allows for much less iterations, avoiding high–dimensional matrix operations, allowing the computational complexity to be reduced from OK3 to OK2. Simulated and real–data results demonstrate the superiority and effectiveness of the proposed method.
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Gusev, S. N., S. V. Zhuravlev und A. V. Popov. „Determination of the Spatial Resolution of Radar Images in Remote Sensing of the Earth“. Journal of the Russian Universities. Radioelectronics 24, Nr. 3 (24.06.2021): 72–80. http://dx.doi.org/10.32603/1993-8985-2021-24-3-72-80.
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Introduction. The analysis of the current state and prospects of space-based radar surveillance tools is important for determining their functions in global aerospace information systems, which aim to monitor air and space, as well as the Earth's surface. Radar surveillance information is used for the purposes of economic analysis, environmental monitoring, mineral search, emergency monitoring, detection and recognition of specified object s at sea and on land, as well as for ensuring national security. In this regard, it is of relevance to develop methods for preliminary assessment of the resolution capacity of novel high-precision onboard radar systems installed on a spacecraft, considering their main technical characteristics, the parameters of the spacecraft movement and the influence of the atmosphere. A priori estimation of spatial resolution values requires a method for calculating the corresponding indicators meeting the required quality of the synthesized radio holograms.Aim. To derive mathematical dependencies and logical rules allowing a priori estimation of the spatial resolution of radar images obtained by the onboard equipment of a radar complex.Materials and methods. Analytical methods were used to determine the resolution error of onboard radar systems with a synthesized aperture in the lateral (azimuthal) direction and range, as well as the theory of radar signal processing.Results. A comparison of the experimental and analytical data on the resolution capacity of an actual radar system confirmed the validity on the proposed method. The developed methodology was used to determine the procedure of calculating the error when estimating the resolution capacity in terms of azimuth and range. Conclusion. The proposed method can be used for both designing novel radar systems and comparing existing radar complexes, depending on the resolution requirements.
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Xin, Wang, Gu Liang, Dong Mingming und Li Xiaolei. „Comparative simulation study on two estimation methods and two control strategies for semi-active suspension“. Advances in Mechanical Engineering 13, Nr. 4 (April 2021): 168781402110073. http://dx.doi.org/10.1177/16878140211007323.
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With regard to the structural characteristics of the McPherson suspension system, when a vehicle is being driven on a rough road surface, the force direction of the suspension varies. This poses challenges to the vehicle’s driving safety and handling stability. Based on Lagrangian equations, this paper proposes a new nonlinear semi-vehicle suspension model and presents comparative studies, conducted through simulation, on the estimated accuracy and computational overhead of the small-computational-overhead extended Kalman filter (EKF) and unscented Kalman estimation (UKF) methods, and on the effectiveness of the skyhook sliding mode control (SHSMC) and nonlinear skyhook-sliding mode control (NSHSMC) semi-active suspension control methods. The response of the vehicle to the state estimation algorithm was evaluated through computer simulations using the Carsim vehicle dynamic software. The simulation results reveal that the vehicle dynamic states were satisfactorily estimated when the vehicle was driven on a rough road surface. Compared with the small-computational-overhead EKF algorithm, the estimated results of these variables based on the UKF algorithm have higher accuracy. However, the UKF algorithm requires longer computation time compared with the EKF algorithm. The SHSMC control algorithm achieved greater improvement for the vehicle’s drive handling stability in the 6–10-Hz vibration region compared with the NSHSMC control algorithm. In a high-frequency region over 10Hz, the semi-active suspension controlled by the SHSMC method had a more adverse effect on the driving comfort.
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Zucconi, Maria, Marco Bovo und Barbara Ferracuti. „Fragility Curves of Existing RC Buildings Accounting for Bidirectional Ground Motion“. Buildings 12, Nr. 7 (21.06.2022): 872. http://dx.doi.org/10.3390/buildings12070872.
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In recent decades, the considerable number of worldwide earthquakes caused considerable damage and several building collapses, underlining the high vulnerability of the existing buildings designed without seismic provisions. In this regard, this work analyses the seismic performance of a reinforced concrete building designed without any seismic criteria, characterized by a seismically-stronger and a seismically-weaker direction, such as several existing reinforced concrete-framed structures designed for vertical load only. The case study building was modelled in OpenSees considering a non-linear three-dimensional model, also accounting for the contribution of joint panel deformability on the global behavior. Thirty bidirectional ground motions have been applied to the structure with the highest component alternatively directed along the two principal building directions. Time-history analyses have been performed for eight increasing hazard levels with the aim of evaluating the influence of bidirectional ground motion on structural response and estimating the seismic vulnerability of the building. The seismic performance of the structures are provided in terms of fragility curves for the two principal directions of the building and for different damage states defined according to the European Macroseismic Scale.
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Protivinsky, Jiri, Monika Kubzova und Martin Krejsa. „Experimental Assessment of Structural Damping of Industrial Boiler Structure“. Key Engineering Materials 738 (Juni 2017): 195–204. http://dx.doi.org/10.4028/www.scientific.net/kem.738.195.
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This article focuses on the estimation of a proper logarithmic damping decrement in industrial boilers when flue gases travel in the vertical direction. The structure for this type of facility is quite unified worldwide. The structural conception is rather simple, and the response to any static loading is predictable. Nevertheless, with regard to dynamics and damping, some specifics in the detailed solution make this system unique. For the purpose of this analysis, a Plexiglas scale model was prepared at a geometric scale of 1:20. A set of experimental modal analyses was performed on the model. Each test focused on the damping effect of specific details and compared it with the common structure without a damping effect. Finally, a site modal analysis was conducted on an actual boiler located in the CHP Torun Plant in Poland. The upper part of the structure was reinforced to have a horizontal deflection of 8 mm and was suddenly released. The resulting movement was recorded with an HD camera linked to a theodolite. Experimental results on the scale model of the actual structure confirmed that damping of this type of structure is significantly higher than that considered for common steel structures.
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YAMAGUCHI, HIROSHI, DAISUKE INOUE, KUNIO SHIMADA, SHIGEMITSU SHUCHI und HIDEYA NISHIYAMA. „PRESSURE CHARACTERISTICS OF ER DAMPER WITH DIFFERENT PISTON VELOCITIES“. International Journal of Modern Physics B 19, Nr. 07n09 (10.04.2005): 1598–604. http://dx.doi.org/10.1142/s0217979205030645.
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A basic experiment for the gap flow in a closed piston - cylinder system of ER fluid was carried out with regard to engineering application to dampers. The purpose of this study is to gain system characteristics and to elucidate flow behaviors of ER fluid in the piston–cylinder system; the model damper. Pressure, which is the system characteristic, was examined in the present study. The test fluid was a smectite ER fluid in silicone oil base of the 3wt% particle dispersion concentration. In the apparatus the piston moves in the vertical direction at a given speed. Theoretical formula of pressure difference is considered by the one-dimensional analysis of the ER flow in the gap of cylinder. It was shown that the response of the pressure was retarded with strong electric field. In comparison with the theoretical estimation and experimental value, the theoretical pressure difference was in good agreement with experimental data. For a sake of giving an insight to flow phenomena, visualization was also achieved using model Newtonian fluid in the piston-cylinder system, and shown that vorticity generated at the rear corner of the piston plays an important role for the pressure characteristic.
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Friberg, Kalervo. „Efficacy of Work–Life Orientation: Region and Parents’ Education as Background Factors“. SAGE Open 10, Nr. 4 (Oktober 2020): 215824402097236. http://dx.doi.org/10.1177/2158244020972364.
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This study detected and analyzed changes that took place in students’ attitudes toward their future education and occupation after completion of the 3-year orientation to work–life through Grades 7 to 9 in different regions in Finland. The changes in the correlations of attitudes were seen as both precursors and consequences of the students’ engagement in the work–life orientation (WLO) program. The changes were postulated not to correlate with the respondents’ region and parents’ education. The empirically measured changes in students’ attitudes served as indicators of the efficacy of WLO. Efficacy referred to the power of WLO to produce effects in the form of changes in attitudes toward educational and occupational choices. Consequently, tentative hypotheses were formed to be tested through empirical observations (measurement points) of WLO. WLO was expected to positively affect student motivation and to guide idiographic decision-making concerning personal goals. Using an alpha level of .05, an independent samples test was conducted to evaluate whether independence, flexibility, and self-direction differed significantly in the measurement groups. For the WLO effect sizes (ES) estimation and for the comparison of the groups, Cohen’s ds were calculated. WLO had a small to medium effect on independence and flexibility, and a near zero effect on self-direction. No notable regional differences in the variance of the students’ attitudes were detected although the social environments differed considerably with regard to industrial structure. The statistically significant proportional differences between the parents’ educational levels did not correlate with the efficacy of WLO.
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Czado, Claudia, und Thomas Nagler. „Vine Copula Based Modeling“. Annual Review of Statistics and Its Application 9, Nr. 1 (07.03.2022): 453–77. http://dx.doi.org/10.1146/annurev-statistics-040220-101153.
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With the availability of massive multivariate data comes a need to develop flexible multivariate distribution classes. The copula approach allows marginal models to be constructed for each variable separately and joined with a dependence structure characterized by a copula. The class of multivariate copulas was limited for a long time to elliptical (including the Gaussian and t-copula) and Archimedean families (such as Clayton and Gumbel copulas). Both classes are rather restrictive with regard to symmetry and tail dependence properties. The class of vine copulas overcomes these limitations by building a multivariate model using only bivariate building blocks. This gives rise to highly flexible models that still allow for computationally tractable estimation and model selection procedures. These features made vine copula models quite popular among applied researchers in numerous areas of science. This article reviews the basic ideas underlying these models, presents estimation and model selection approaches, and discusses current developments and future directions.
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SCHACK, BÄRBEL, PETER RAPPELSBERGER, CHRISTOPH ANDERS, SABINE WEISS und EVA MÖLLER. „QUANTIFICATION OF SYNCHRONIZATION PROCESSES BY COHERENCE AND PHASE AND ITS APPLICATION IN ANALYSIS OF ELECTROPHYSIOLOGICAL SIGNALS“. International Journal of Bifurcation and Chaos 10, Nr. 11 (November 2000): 2565–86. http://dx.doi.org/10.1142/s0218127400001651.
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Neuronal activity during information processing and muscle activity are generally characterized by oscillations. Mostly, widespread areas are involved and electrophysiological signals are measured on different sites of the cortex or of the muscle. In order to investigate functional relationships between different components of multidimensional electrophysiological signals, coherence and phase analyses turned out to be useful tools. These parameters allow the investigation of synchronization phenomena with regard to oscillations of defined frequencies or frequency bands. Coherence and phase are closely connected spectral parameters. Coherence may be understood as a measure of phase stability. Whereas coherence describes the amount of common information with regard to oscillations within certain frequency bands, the corresponding phase, from which time delays of these oscillations can be computed, hints at the direction of information transfer through oscillation. Coherence and phase analysis of surface EMG during continuous activity of deep and superficial muscles show distinct differences due to volume conduction properties of myoelectrical signals. Superficial activity therefore is characterized by significant coherence and stable phase relationships, which, additionally, can be used to determine motor unit action potential (MUAP) propagation velocity along the fibre direction without application of invasive methods. Deep muscle activity lacks significant coherence. Mental processes can be very brief and cooperation between different areas may be highly dynamic. For this reason in addition to usual Fourier estimation of coherence and phase, a two-dimensional approach of adaptive filtering was developed to estimate coherence and phase continuously in time. Statistical and dynamic properties of instantaneous phase are discussed. In order to demonstrate the value of this method for studying higher cognitive processes the method was applied to EEG recorded during word processing. During visual presentation of abstract nouns an information transfer through the propagation of oscillations from visual areas to frontal association areas in the α1-frequency band could be verified within the first 400 ms. In contrast, in case of auditory presentation positive phases from the temporal electrode locations T3 and T4 towards the occipital areas appear within the time interval of 300 ms–600 ms. The α1-band predominately seems to reflect sensory processing and attention processes.
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Aronova, Ekaterina, Goran Radovic, Vera Murgul und Nikolay Ivanovich Vatin. „Solar Power Opportunities in Northern Cities (Case Study of Saint-Petersburg)“. Applied Mechanics and Materials 587-589 (Juli 2014): 348–54. http://dx.doi.org/10.4028/www.scientific.net/amm.587-589.348.
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With the purpose to ensure extra solar power for buildings and improve quality of urban environment solar power has appeared to be sought-after in the majority of southern countries. In the case of the Northwest Region of Russia estimation of existing regional power reserves for construction sector is the fundamental factor when an issue of achieving possible ways to supply buildings with solar-based power is considered. The article deals with the methods and calculations made to obtain the data on solar radiation effects on sloping surfaces oriented in different cardinal directions in regard to Saint-Petersburg weather-related conditions. Electric power generation using solar photovoltaic modules (PV modules) has been defined under actual operating conditions.
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Hrynchak, Nataliia, Olha Yatsenko, Olena Bulatova und Olena Ptashchenko. „Problems realating to the statistical research of the national market of logistics services in war conditions“. Statistics in Transition new series 24, Nr. 1 (24.02.2023): 13–28. http://dx.doi.org/10.59170/stattrans-2023-002.
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The article discusses the theoretical principles of statistical research with regard to the national market of logistics services during wartime. The system of statistical indicators of the research of the logistics services market is structured through the allocation of separate blocks of indicators by priority of their estimation in war conditions. The market of logistics services of Ukraine is characterised by selected blocks of indicators. The paper identifies the main structural changes that occurred due to the hostilities faced by the country. Moreover, the authors determine the main factors influencing the functioning of the analysed market during war, as the statistical study of these factors is considered necessary for the transformation and development of logistics services. It is substantiated that taking into account such statistical indicators as the level and availability of logistics infrastructure, security, the human factor and changes in legislation are likely to result in a new alternative direction of logistics routes and contribute to the development of the logistics services market in general. The authors proposed the construction of a centralised electronic service (or several services) with the purpose of consolidating information about the logistics infrastructure. The software system should offer the option of an operational interactive visualisation.
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Shul, Yusun, und Jung-Woo Choi. „Divided spectro-temporal transformer for sound event localization and detection in real scenes“. Journal of the Acoustical Society of America 154, Nr. 4_supplement (01.10.2023): A256—A257. http://dx.doi.org/10.1121/10.0023458.
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Sound event localization and detection (SELD) involves the detection of sound events (SED) and the estimation of their direction of arrival (DoA) by utilizing multichannel sound signals. Recent research in SELD has predominantly focused on deep neural network (DNN) based models, which specifically emphasize learning temporal context. Examples of these models include the convolutional recurrent neural network (CRNN) and the ResNet-conformer architecture, which handle spectral and channel information only as the embeddings of temporal features. To fully exploit spectral information providing a crucial cue for both SED and DoA, it is imperative to devise a network architecture that effectively learns both spectral and temporal contexts. In this regard, we propose a divided transformer architecture that separately identifies the spectral and temporal context to encourage the model to learn more spectral characteristics of signals while retaining the temporal context. The efficacy of the divided spectro-temporal transformer approach is validated using the DCASE 2022 and 2023 challenge task 3 datasets. Furthermore, a series of parameter studies carried out to optimize the performance of SELD demonstrates that the number of frequency bins for attention and the pooling location impact the performance, and the divided spectro-temporal transformer is beneficial for both SED and DoA.
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Badach, Elżbieta, und Piotr Cymanow. „IMPACT OF AGGLOMERATIONS ON SOCIAL, AGRICULTURAL AND ENVIRONMENTAL TRANSFORMATIONS OF NEIGHBOURING MUNICIPALITIES“. Annals of the Polish Association of Agricultural and Agribusiness Economists XXI, Nr. 4 (29.11.2019): 24–35. http://dx.doi.org/10.5604/01.3001.0013.6023.
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The main research objective was to define the intensity of migration processes in metropolitan areas, and highlight the scale of deagrarisation processes in neighbouring regions where agricultural functions are on the decline. The article presents the dynamics of changes related to the number of agricultural farms located in suburban areas in the years 1996-2010. It also includes an analysis of population flows between the city and the countryside. The study covers 4 agglomerations – Warszawa, Kraków, Wrocław and Poznań – and includes all the municipalities adjacent to the abovementioned cities. The study is based on data from the last three Agricultural Censuses and resources from the Local Data Bank. The data was used to create linear models illustrating tendency and dynamics indicators. In each of the agglomerations, it is possible to observe a visible decrease in the number of agricultural farms, whereas this phenomenon is the most conspicuous in municipalities located around Warszawa and Kraków. This points to increased dynamics of urbanisation processes with regard to major cities in Poland. Detailed analysis points to the concentration of capital and the related departure from the agricultural function in municipalities located in the direct vicinity of main transit routes. The analysis of population flows reveals that the dominant direction of migration is towards suburban municipalities. Apart from accessibility in terms of transport, the most significant factors, when it comes to making decisions on where to settle, include the attractive landscape and outstanding natural features of neighbouring municipalities. Models of trend estimation developed for individual municipalities, which describe the extent of migration from cities to neighbouring municipalities, expressly point to the increasing degree of this phenomenon. The greatest flow in this direction was observed in the years 2008-2010.
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Legusha, F., und Yu Popov. „Numerical simulation of acoustic signal propagation in underwater acoustic duct“. Transactions of the Krylov State Research Centre 2, Nr. 396 (21.05.2021): 122–33. http://dx.doi.org/10.24937/2542-2324-2021-2-396-122-133.
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Object and purpose of research. The progress in numerical simulation methods significantly widens the capabilities of theoretical analysis in the tasks requiring extensive calculations and input data sets, like sound propagation at sea. This paper discusses the feasibility of a numerical model describing the physics of acoustic signal propagation in a deep-water channel. Materials and methods. Acoustic signal calculation is performed as per the ray-path theory with a numerical model taking into account depth-wise variations of sound velocity and seabed parameters. Main results. It was shown that depending on the vertical distribution of sound speed, the source depth and distance, the acoustic wave propagation direction can change over significant range of angles the in vertical plane. In this regard it is advisable to calculate the real target force of an object of complex geometry not only from heading angle in horizontal plane but also in terms of the possible range of angles in the vertical plane. Conclusion. Model-analyzed angles range of long-range wave propagation may be used for change estimation of object target force characteristics. Practical significance of the study lies in improving the methods of calculation of the real target force of complex shape objects in terms of state-of the art capabilities of simulating the propagation of acoustic signals conditions in the ocean.
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Gorbunova, M. L., und Yao Donatien Kouassi. „ESTIMATION OF THE ECONOMIC EFFICIENCY OF AN INVESTMENT PROJECT FOR THE INTRODUCTION OF SOLAR PANELS IN BUILDINGS OF AN ADMINISTRATIVE QUARTER IN THE MUNICIPALITY OF PLATEAU (CÔTE D’IVOIRE)“. Globus: economy sciences 7, Nr. 4(44) (19.11.2021): 24–36. http://dx.doi.org/10.52013/2713-3052-44-4-5.
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The use of renewable energy sources is a topical direction in the development of the energy industry in the modern world. However, when investing, choosing the optimal strategy is essential to keep costs down. The goal is to evaluate the efficiency of using solar panels parallel to the electric grid for the plateau municipality, the Republic of Cote d’Ivoire. The objectives of the study in this regard are to determine the strategy to the greatest extent, affecting the reduction of the investment cost when introducing a solar battery project, the calculation of economic indicators that allow us to assess the risks when making decisions to implement the investment. For the assessment, a technique is presented that differs from the existing complex taking into account specific indicators (average annual insolation, efficiency of solar panels, temperature coefficient, price of 1 M ^ 2 solar panels, transportation costs, cost of installation work, depreciation period, maintenance costs, property tax, the cost of training employees. The methodology includes the author’s recommendations, taking into account the specific features of determining the indicators of the annual economic effect, NPV. IRR, DPP for a solar battery project. A comparative analysis of an autonomous SES and operating in parallel with the electric grid. Conclusions: SES in parallel with a network of solar power plants. reduces the cost of the project investment, and also hinders the payback period of the project.
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Alihodzic, Rifat, Vera Murgul, Nikolay Vatin, Ekaterina Aronova, Vojislav Nikolić, Milan Tanić und Danica Stanković. „Renewable Energy Sources Used to Supply Pre-School Facilities with Energy in Different Weather Conditions“. Applied Mechanics and Materials 624 (August 2014): 604–12. http://dx.doi.org/10.4028/www.scientific.net/amm.624.604.
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Pre-school facilities are considered to be specific buildings in the matter of construction and renovation. Space-planning features in design for pre-school facilities create special conditions for solar power use to ensure heat and power supply. The article deals with estimation of incoming solar power in reference to the surfaces oriented in different cardinal directions under the weather conditions of the city of Saint-Petersburg (Russia) and the city of Nish (Serbia). A model of how to ensure power supply for a kindergarten of the city of Nish is presented on the basis of the calculations analysis. The cases with regard to completed projects designed to use renewable energy sources in order to supply pre-school facilities with energy in other weather conditions are given herein.
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Albahli, Saleh, Aun Irtaza, Tahira Nazir, Awais Mehmood, Ali Alkhalifah und Waleed Albattah. „A Machine Learning Method for Prediction of Stock Market Using Real-Time Twitter Data“. Electronics 11, Nr. 20 (21.10.2022): 3414. http://dx.doi.org/10.3390/electronics11203414.
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Finances represent one of the key requirements to perform any useful activity for humanity. Financial markets, e.g., stock markets, forex, and mercantile exchanges, etc., provide the opportunity to anyone to invest and generate finances. However, to reap maximum benefits from these financial markets, effective decision making is required to identify the trade directions, e.g., going long/short by analyzing all the influential factors, e.g., price action, economic policies, and supply/demand estimation, in a timely manner. In this regard, analysis of the financial news and Twitter posts plays a significant role to predict the future behavior of financial markets, public sentiment estimation, and systematic/idiosyncratic risk estimation. In this paper, our proposed work aims to analyze the Twitter posts and Google Finance data to predict the future behavior of the stock markets (one of the key financial markets) in a particular time frame, i.e., hourly, daily, weekly, etc., through a novel StockSentiWordNet (SSWN) model. The proposed SSWN model extends the standard opinion lexicon named SentiWordNet (SWN) through the terms specifically related to the stock markets to train extreme learning machine (ELM) and recurrent neural network (RNN) for stock price prediction. The experiments are performed on two datasets, i.e., Sentiment140 and Twitter datasets, and achieved the accuracy value of 86.06%. Findings show that our work outperforms the state-of-the-art approaches with respect to overall accuracy. In future, we plan to enhance the capability of our method by adding other popular social media, e.g., Facebook and Google News etc.
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Hanák, Tomáš, und Carles Serrat. „Analysis of Construction Auctions Data in Slovak Public Procurement“. Advances in Civil Engineering 2018 (03.12.2018): 1–13. http://dx.doi.org/10.1155/2018/9036340.
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The requirement for efficient public spending leads contracting authorities to use electronic reverse auctions (e-RA), a tool that allows achieving financial savings. In this study, we aim to explore the relationships between the different acting e-RA variables and to check for predictive models in order to infer on the savings amount in construction public procurement. Data on real construction auctions in Slovakia were statistically analysed by means of graphics tools, multiple regression analysis, test, and statistics for measuring the association between categorical variables. The results revealed that one should take the type of contract into account when considering the use of e-RA. This research provides several implications for purchasing practitioners in the area of construction procurement, especially with regard to the level of competition in the auction and estimation of savings potential. Presented findings aid managerial decision-making process of e-RA adoption. At the end, recommended future research directions in the investigated area are outlined.
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Inman, D. L., und W. H. Quinn. „CURRENTS IN THE SURF ZONE“. Coastal Engineering Proceedings 1, Nr. 2 (01.01.2000): 3. http://dx.doi.org/10.9753/icce.v2.3.
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Surface and bottom currents in the surf zone were measured at 15 equally spaced points along two straight beaches with approximately parallel bottom contours. The measurements showed that offshore currents predominate over onshore currents at the bottom, while at the surface there is a slight predominance in the onshore direction. With regard to the longshore component, it was found that surface and bottom currents have a similar velocity distribution. The variability of the longshore component as measured by its standard deviation is equal to or larger than the mean longshore velocity. This wide variation in longshore currents indicates the impracticability of estimating the mean velocity from a single observation of longshore current. It was found that the momentum approach to the prediction of longshore currents by Putnam, Munk and Traylor (1949) leads to useful forecasts provided the beach friction coefficient k is permitted to vary with the longshore velocity, V. The indicated relation is k~v^(-3/2).
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Ijiga, Owoicho E., Olayinka O. Ogundile, Ayokunle D. Familua und Daniel J. J. Versfeld. „Review of Channel Estimation for Candidate Waveforms of Next Generation Networks“. Electronics 8, Nr. 9 (29.08.2019): 956. http://dx.doi.org/10.3390/electronics8090956.
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The advancement in wireless communication applications encourages the use of effective and efficient channel estimation (CE) techniques because of the varying behaviour of the Rayleigh fading channel. In most cases, the emphasis of most proposed CE schemes is to improve the CE performance and complexity for ensuring quality signal reception and improved system throughput. Candidate waveforms whose designs are based on filter bank multi-carrier (FBMC) modulation techniques such as filter bank orthogonal frequency division multiplexing based on offset quadrature amplitude modulation (OFDM-OQAM), universal filtered multicarrier (UFMC) and generalised frequency division multiplexing based on offset quadrature amplitude modulation (GFDM-OQAM) are no exception to the use of these proposed CE techniques in the literature. These schemes are considered as potential waveform candidates for the physical/media access control layer of the emerging fifth generation (5G) networks. Therefore, pinpoint CE techniques represent an important requirement for these waveforms to attain their full potentials. In this regard, this paper reviews the concept of CE as applicable to these waveforms as well as other waveform candidates under consideration in the emerging 5G networks. Since the design of the majority of the waveform candidates is filter based, a review of the general filter design considerations is presented in this paper. Secondly, we review general CE techniques for candidate waveforms of next generation networks and classify some of the studied CE techniques. In particular, we classify the CE schemes used in filter bank OFDM-OQAM and GFDM-OQAM based transceivers and present a performance comparison of some of these CE schemes. Besides, the paper reviews the performances of two linear CE schemes and three adaptive based CE schemes for two FBMC based waveform candidates assuming near perfect reconstruction (NPR) and non-perfect reconstruction (Non-PR) filter designs over slow and fast frequency selective Rayleigh fading channels. The results obtained are documented through computer simulations, where the performances of the studied CE schemes in terms of the normalised mean square error (NMSE) are analysed. Lastly, we summarise the findings of this work and suggest possible research directions in order to improve the potentials of the studied candidate waveforms over Rayleigh fading channels.
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Korovin, Sergey Semenovich. „Theory and organization of complex control at Physical Education“. Samara Journal of Science 8, Nr. 1 (28.02.2019): 253–59. http://dx.doi.org/10.17816/snv201981307.
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The quality of the directed usage of physical culture in education values, comprehensive and complex reproduction of the personality, demands a system organization of physical education processes management, which, in its turn, makes it necessary to create and realize a system of complex control of physical culture translators processes and the results of its assimilation. Complex control in this case is a system of management, organization, diagnostics and estimation actions to define the effectiveness of physical education process (processes of physical culture assimilation) and the quality of its correspondence to the established purposes-demands. The system of complex control is represented by two components - directions of its organization and realization: control of a physical education system (including control of external environment factors; physical education competences; educational environment) and the control of a physical education object (including medico biological, psychological and pedagogical forms of control concerning the basic and physical culture of the personality separately). Psychological and pedagogical control is realized with regard to total sizes of the body, physical, technical, behavior, mental and theoretical readiness as well as with regard to each component of the basic culture of the personality (ethical, aesthetic, civil, labour, intellectual (cognitive), communicative). The medico biological form of control comprises diagnostics and evaluation of physical growth data (total sizes of the body, first of all), correspondence of the passport age to the biological and functional readiness (the state of the vascular and respiratory systems), physical working capacity and physical adaptation as well as general state of health.
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Tourani, Ali, Hriday Bavle, Jose Luis Sanchez-Lopez und Holger Voos. „Visual SLAM: What Are the Current Trends and What to Expect?“ Sensors 22, Nr. 23 (29.11.2022): 9297. http://dx.doi.org/10.3390/s22239297.
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In recent years, Simultaneous Localization and Mapping (SLAM) systems have shown significant performance, accuracy, and efficiency gain. In this regard, Visual Simultaneous Localization and Mapping (VSLAM) methods refer to the SLAM approaches that employ cameras for pose estimation and map reconstruction and are preferred over Light Detection And Ranging (LiDAR)-based methods due to their lighter weight, lower acquisition costs, and richer environment representation. Hence, several VSLAM approaches have evolved using different camera types (e.g., monocular or stereo), and have been tested on various datasets (e.g., Technische Universität München (TUM) RGB-D or European Robotics Challenge (EuRoC)) and in different conditions (i.e., indoors and outdoors), and employ multiple methodologies to have a better understanding of their surroundings. The mentioned variations have made this topic popular for researchers and have resulted in various methods. In this regard, the primary intent of this paper is to assimilate the wide range of works in VSLAM and present their recent advances, along with discussing the existing challenges and trends. This survey is worthwhile to give a big picture of the current focuses in robotics and VSLAM fields based on the concentrated resolutions and objectives of the state-of-the-art. This paper provides an in-depth literature survey of fifty impactful articles published in the VSLAMs domain. The mentioned manuscripts have been classified by different characteristics, including the novelty domain, objectives, employed algorithms, and semantic level. The paper also discusses the current trends and contemporary directions of VSLAM techniques that may help researchers investigate them.
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Floris, Claudia, Sarah Solbiati, Federica Landreani, Gianfranco Damato, Bruno Lenzi, Valentino Megale und Enrico Gianluca Caiani. „Feasibility of Heart Rate and Respiratory Rate Estimation by Inertial Sensors Embedded in a Virtual Reality Headset“. Sensors 20, Nr. 24 (14.12.2020): 7168. http://dx.doi.org/10.3390/s20247168.
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Virtual reality (VR) headsets, with embedded micro-electromechanical systems, have the potential to assess the mechanical heart’s functionality and respiratory activity in a non-intrusive way and without additional sensors by utilizing the ballistocardiographic principle. To test the feasibility of this approach for opportunistic physiological monitoring, thirty healthy volunteers were studied at rest in different body postures (sitting (SIT), standing (STAND) and supine (SUP)) while accelerometric and gyroscope data were recorded for 30 s using a VR headset (Oculus Go, Oculus, Microsoft, USA) simultaneously with a 1-lead electrocardiogram (ECG) signal for mean heart rate (HR) estimation. In addition, longer VR acquisitions (50 s) were performed under controlled breathing in the same three postures to estimate the respiratory rate (RESP). Three frequency-based methods were evaluated to extract from the power spectral density the corresponding frequency. By the obtained results, the gyroscope outperformed the accelerometer in terms of accuracy with the gold standard. As regards HR estimation, the best results were obtained in SIT, with Rs2 (95% confidence interval) = 0.91 (0.81−0.96) and bias (95% Limits of Agreement) −1.6 (5.4) bpm, followed by STAND, with Rs2 = 0.81 (0.64−0.91) and −1.7 (11.6) bpm, and SUP, with Rs2 = 0.44 (0.15−0.68) and 0.2 (19.4) bpm. For RESP rate estimation, SUP showed the best feasibility (98%) to obtain a reliable value from each gyroscope axis, leading to the identification of the transversal direction as the one containing the largest breathing information. These results provided evidence of the feasibility of the proposed approach with a degree of performance and feasibility dependent on the posture of the subject, under the conditions of keeping the head still, setting the grounds for future studies in real-world applications of HR and RESP rate measurement through VR headsets.
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Menéndez, Oswaldo, Marcelo Pérez und Fernando Auat Cheein. „Visual-Based Positioning of Aerial Maintenance Platforms on Overhead Transmission Lines“. Applied Sciences 9, Nr. 1 (04.01.2019): 165. http://dx.doi.org/10.3390/app9010165.
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Unmanned aerial vehicles (UAVs) are an emerging and promising alternative for monitoring of transmission lines in terms of flexibility, complexity, working speed, and cost. One of the main challenges is to enable UAVs to become as autonomous as possible. A vital component toward this direction is the robust and accurate estimation of the UAV placement with respect to the transmission grid. This work faces this challenge by developing a transmission line autonomous tracking system, which allows the placement of a commercial drone over a transmission grid using a monocular camera. This feature provides accurate positioning for the vehicle even where the Global navigation satellite system (GNSS) signal is denied, enabling to report the status of transmission lines, at any time. The system isolates transmission grid conductors in each acquired RGB-image using an image-processing algorithm based on Hough transform, morphological operations, and Gabor filters. With this information, the system computes the location of the UAV using a geometric approach that relates transmission lines building parameter and optical geometry. However, it has the problem of gradual error accumulation when the drone moves. In this regards, the estimated position of the drone is computed by the maximum likelihood estimation (MLE) by the position information estimated by visual-system, the inertial measurement unit (IMU) and GNSS. The proposed positioning system showed an efficiency of 91.44% in field experimentation in the extraction of transmission conductor, with a root mean square the error of 0.18 m in the UAV localization.
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Tzelepi, Vasiliki, Myrto Zeneli, Dimitrios-Sotirios Kourkoumpas, Emmanouil Karampinis, Antonios Gypakis, Nikos Nikolopoulos und Panagiotis Grammelis. „Biomass Availability in Europe as an Alternative Fuel for Full Conversion of Lignite Power Plants: A Critical Review“. Energies 13, Nr. 13 (01.07.2020): 3390. http://dx.doi.org/10.3390/en13133390.
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Biomass has been demonstrated as a capable source of energy to fulfill the increasing demand for clean energy sources which could last a long time. Replacing fossil fuels with biomass-based ones can potentially lead to a reduction of carbon emissions, which is the main target of the EU climate strategy. Based on RED II (revised Renewable Energy Directive 2018/2001/EU) and the European Green Deal, biomass is a promising energy source for achieving carbon neutrality in the future. However, the sustainable potential of biomass resources in the forthcoming decades is still a matter of question. This review aims at estimating the availability of biomass for energy reasons in the EU, and to evaluate its potential to meet the coal power plant capacity of the main lignite-producer countries, including Germany, Poland and Greece. Plants in line with the sustainability criteria of RED II have been selected for the preliminary estimations concerning their full conversion to the biomass power concept. Furthermore, the various barriers to biomass utilization are highlighted, such as the stranded asset risk of a future coal phase-out scenario, biomass supply chain challenges, biomass availability in main lignite-producer EU countries, the existing full conversion technologies, and biomass cost. A variety of challenges in the scenario of lignite substitution with biomass in a plant are investigated in a SWOT (strengths, weaknesses, opportunities, and threats) analysis. Technological risks and issues should be tackled in order to achieve the coal phase-out EU goal, mainly with regard to the supply chain of biomass. In this direction, the development of logistics centers for the centralized handling of biomass is strongly recommended.
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Goharnejad, Hamid, Will Perrie, Bash Toulany, Mike Casey und Minghong Zhang. „Clustering of Climate Change Impacts on Ocean Waves in the Northwest Atlantic“. Journal of Atmospheric and Oceanic Technology 39, Nr. 2 (Februar 2022): 237–57. http://dx.doi.org/10.1175/jtech-d-21-0053.1.
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Abstract The provision of reliable results from numerical wave models implemented over vast ocean areas can be considered as a time-consuming process. In this regard, the estimation of areas with maximum similarity in wave climate spatial areas and the determination of associated representative point locations for these areas can play an important role in climate research and in engineering applications. To deal with this issue, we apply a state-of-the-art clustering method, Geo-SOM, to determine geographical areas with similar wave regimes, in terms of mean wave direction (MWD), mean wave period (T0), and significant wave height (Hs). Although this method has many strengths, a weakness is related to detection and accounting of the most extreme and rare events. To resolve this deficiency, an initial preprocessing method (called PG-Geo-SOM) is applied. To evaluate the performance of this method, extreme wave parameters, including Hs and T0, are calculated. We simulate the present climate, represented as 1979 to 2017, compared to the future climate, 2060–98, following the Intergovernmental Panel on Climate Change (IPCC) future scenario RCP8.5 in the northwestern Atlantic Ocean. In this approach, the wave parameter data are divided into distinct groups, or clusters, motivated by their geographical positions. For each cluster, the centroid spatial point and the time series of data are extracted, for Hs, MWD, and T0. Extreme values are estimated for 5-, 10-, 25-, 50-, and 100-yr return periods, using Gumbel, exponential, and Weibull stochastic models, for both present and future climates. Results show that for parameter T0, the impact of climate change for the study area is a decreasing trend, while for Hs, in coastal and shelf areas up to about 1000 km from the coastline, increasing trends are estimated, and in open-ocean areas, far from the coast, decreasing trends are obtained.
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He, Xing, Changgen Peng, Lin Wang, Weijie Tan und Zifan Wang. „Stable and Fast Deep Mutual Information Maximization Based on Wasserstein Distance“. Entropy 25, Nr. 12 (30.11.2023): 1607. http://dx.doi.org/10.3390/e25121607.
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Deep learning is one of the most exciting and promising techniques in the field of artificial intelligence (AI), which drives AI applications to be more intelligent and comprehensive. However, existing deep learning techniques usually require a large amount of expensive labeled data, which limit the application and development of deep learning techniques, and thus it is imperative to study unsupervised machine learning. The learning of deep representations by mutual information estimation and maximization (Deep InfoMax or DIM) method has achieved unprecedented results in the field of unsupervised learning. However, in the DIM method, to restrict the encoder to learn more normalized feature representations, an adversarial network learning method is used to make the encoder output consistent with a priori positively distributed data. As we know, the model training of the adversarial network learning method is difficult to converge, because there is a logarithmic function in the loss function of the cross-entropy measure, and the gradient of the model parameters is susceptible to the “gradient explosion” or “gradient disappearance” phenomena, which makes the training of the DIM method extremely unstable. In this regard, we propose a Wasserstein distance-based DIM method to solve the stability problem of model training, and our method is called the WDIM. Subsequently, the training stability of the WDIM method and the classification ability of unsupervised learning are verified on the CIFAR10, CIFAR100, and STL10 datasets. The experiments show that our proposed WDIM method is more stable to parameter updates, has faster model convergence, and at the same time, has almost the same accuracy as the DIM method on the classification task of unsupervised learning. Finally, we also propose a reflection of future research for the WDIM method, aiming to provide a research idea and direction for solving the image classification task with unsupervised learning.
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Pretorius, CC, RJ Mostert, TW Mukarati und VM Mathoho. „Microstructural influences on the damage evolution and kinetics of high temperature hydrogen attack in a C-0.5 Mo welded joint“. Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 40, Nr. 1 (24.01.2022): 212–23. http://dx.doi.org/10.36303/satnt.2021cosaami.40.
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In the refining industry, steels can be susceptible to a damage mechanism known as high temperature hydrogen attack (HTHA). The detection of damage in such structures through non destructive testing (NDT) requires insight into the damage development in various parts of welded joints. Once damage is detected, the tracking of the damage progression and estimation of remaining life is problematic. The performance of C-0.5 Mo steels in such environments is also variable, and the current tendency is to regard the HTHA resistance of C-0.5 Mo as similar to that of carbon steels. The current investigation explores the possibility of using high-temperature capsule strain-gauges for the in-situ evaluation of swelling – which generally accompanies HTHA in susceptible steels – and, thereby, evaluate the development and kinetics of HTHA damage for a C-0.5 Mo steel welded joint. Specimens were prepared representing the base metal (BM), the HAZ region, both fine-grained and coarse-grained, and the weld-metal (WM). The specimens were exposed to hydrogen at 200 bar at a temperature of 500 °C in an autoclave, with certain specimens fitted with high-temperature strain gauges; i.e. instrumented test labelled as IWM, IHAZ and IBM. Metallographic evaluation of the specimens – regarding the three locations mentioned – were performed; with exposure times reflecting both incipient and advanced damage. In the case of the base metal and the fine grained HAZ, and after pronounced damage, macrocracks were observed. The orientation and location of these cracks were aligned with the rolling direction, and the cracks were evident in the through-thickness plane of the plate. It was found that the reason for this observation was due to preferential damage accumulation within banded regions, where high concentrations of carbides were observed. A sigmoidal equation was developed that described the swelling kinetics of the HAZ. The expression of swelling-induced strain rate (SISR) versus time showed a low initial SISR until incipient damage is formed, followed by accelerated attack. The peak SISR was observed midway through the damage evolution, where after the SISRs decreased as the presense of carbides – that feed the methane reaction – diminishes. It is proposed that the attachment of the encapsulated strain gauges to structures or components where HTHA damage is suspected, will assist in the tracking of damage and the estimation of remaining life; if used in conjunction with the developed sigmoidal equation.
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Gofman, O. P. „History of research of phytomass of steppe vegetable groupments in reserve steppe «Askania-Nova»“. Ecology and Noospherology 27, Nr. 3-4 (20.09.2016): 35–46. http://dx.doi.org/10.15421/031612.
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Complex research of productive processes of ecosystems of different level was begun by the International union of biological sciences (International Union of Biological Sciences – IUBS), that in 1964 initiated development of the International biological program (International Biological Program, IBP) for research of the biological productivity of biogeocenosis of dry land and reservoirs. Scientists from many countries, that participated in execution put IBP of tasks, investigated the biological productivity of natural and created by the man of vegetable and animal community in the scale of all planet. Research of the biological productivity and phytomass on territory of dry steppe in Askania-Nova began to carry out yet 150 over back. Unfortunately, there were protracted gaps in researches, however, beginning from 1949 they can be considered continuous. And without regard to the slump of interest in the study of the productivity in 1990–2000, in Biosphere reserve «Askania-Nova», due to the active collective of scientists, research not interrupted. Therefore the far of fact sheets accumulated as a result of the advanced study of many researchers. In summarizing works for histories of botanical researches of askanian steppe authors anymore paid attention to description of history of reserve, in works the given description of researchers of the protected steppe with pointing of direction of their works, analysis of succession changes of vegetation, research of change of floristic composition, but the results of study of phytomass are not almost lighted up. Thus there was an urgent necessity of estimation and generalization up-to-date development of science of previous works of scientists in relation to above-ground and underground phytomass of vegetable community of askanian steppe. Aim of this work : to systematize and conduct the retrospective review of the advanced studies there are the lighted up results of research of above-ground and underground phytomass of vegetable community of askanian steppe in that. Materials scientific publications served as for work, scientific current documentation of Biosphere reserve «Askania-Nova» the names of F. E. Falz-Fein and Askania Nova institute of animal breeding in the steppe regions named after M. F. Ivanov. The worked out sources were brought to the bibliographic database, spreadsheet of Microsoft Excel executed in a format. To the table basic descriptions of literary source were brought in: the name of work, year of publication, name of edition, direction of researches, short annotation. For this temporal segment 3 stages of researches are distinguished: І (1842–1948) – for it typical works of descriptive direction; ІІ (1948–1990) – the subjects of the advanced studies of ecological direction are distinguished; ІІІ (1990 till this time) is appearance of the advanced studies sanctified to the study of phytomass by means of the new controlled from distance methods of research. First period protracted, but it only through considerable interruption in researches after works of F. Teetzmann in 1845, up to 1924, when in the Askania-Nova begins to work M. S. Shalyt. And this period differs in the least amount of the written works (4). The considerable are accumulated the archived materials on phytomass give an opportunity more detailed to describe her changes and dynamics.
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Zvonarev, V. V., V. F. Pimenov und A. S. Popov. „Methodology for estimating reception efficiency of mutually correlated or in- phase signals at diversity transmission“. Issues of radio electronics, Nr. 12 (03.02.2021): 38–43. http://dx.doi.org/10.21778/2218-5453-2020-12-38-43.
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The article describes and theoretically substantiates the potential technical capabilities of spatially separated earth stations (ES). When several ESs emit in-phase or mutually pairwise correlated signals in the direction of one received antenna of the object, the total level of the sum of emissions at its output (at the input of the receiving path) may be several times higher than the sum of the powers of these signals. In this regard, the article investigates the influence of the phase difference of the transmitted signals on the value of their total average power at the input of the receiving path. In the case of addition of common-mode signals, a formula is used to calculate in which the power of harmonic radiation is proportional to the square of the sum of the amplitude of the common-mode signals. This paradox is also valid for pairwise cross-correlated signals. The presented technique for evaluatingтthe effectivenessтallows one to establish not only the dependence of the energy ratios on the nonтenergy parameter, but also to determine the number of low-power ESs required to ensureтthe required signal level at the input of the receiving device. The use of the presented technique makes it possible to evaluate the efficiency of receiving a combined high-power signal for a differentтnumber of emitters that form in-phase or pairwise mutual correlation of signals at the receiving point.