An orbital angular momentum acoustic metasurface for underwater defect detection

Fourier diffraction theorem can rapidly predict scattering characteristics of scatterers. This paper theoretically proposes Orbital Angular Momentum (OAM) to simplify the reference library in the underwater Fourier diffraction theorem. An acoustic metasurface is designed to replace the traditional phased array, meanwhile the underwater defect detection combining OAM and Fourier diffraction theorem is verified in the simulation. This acoustic metasurface has a high signal-to-noise ratio (SNR) when used for underwater defect detection. Compared with the traditional underwater defect detection method, the underwater defect detection method proposed in this paper has the advantages of simple structure and no reference pattern library.

Total-internal-reflection deflectometry for measuring small deflections of a fluid surface

We describe a method that uses total internal reflection at the water–air interface inside a large, transparent tank, to measure the interface’s deflections. Using this configuration, we obtain an optical set-up where the liquid surface acts as a deformable mirror. The set-up is shown to be extremely sensitive to very small disturbances of the reflecting water surface, which are detected by means of visualising the reflections of a reference pattern. When the water surface is deformed, it reflects a distorted image of the reference pattern, similar to a synthetic Schlieren set-up. The distortions of the pattern are analysed using a suitable image correlation method. The displacement fields thus obtained correlate to the local spatial gradients of the water surface. The gradient fields are integrated in a least-squares sense to obtain a full instantaneous reconstruction of the water surface. This method is particularly useful when a solid object is placed just above water surface, whose presence makes the liquid surface otherwise optically inaccessible. Graphical abstract

Planar Array Failed Element(s) Radiation Pattern Correction: A Comparison

Phased arrays are widely used in different fields, such as broadcasting, radar, optics, and space communications. The principle of phased arrays is to generate a directed signal from a large number of antennas to be steered at any desired angle. This, however, increases the probability of defective elements in an array. Faulty elements in an array cause asymmetry and result in increased sidelobe levels which rigorously distort the radiation pattern. Increased sidelobe radiation wastes energy and can cause interference by radiating and receiving signals in unintended directions. Therefore, it is necessary to find a method that can provide accuracy in the radiation pattern transmitted or received in the presence of failed element(s) in an array. This paper compares the few available optimization methods, namely, simulated annealing (SA), Genetic Algorithm (GA), Particle Swarm Optimization (PSO), and Pattern Search (PS) methods. For each method, various types of failures were examined, and the most suitable techniques to recover the far-field radiation are recommended. The optimization is then carried out by selecting the optimal weights of the remaining working elements in the planar array. The optimized radiation pattern’s efficiency was evaluated by comparing the Signal to Noise Ratio (SNR) value of the optimized radiation with reference and failed radiation patterns. The PSO method showed a better performance compared to all the other methods in reducing the failed radiation pattern’s SNR value. In various types of failure tests, this method reduced the failed radiation pattern’s SNR from 1 to 10 dB. This method also successfully produced a radiation pattern that closely matches the reference pattern before any failed element(s) are presented in the array. The life cycle of a planar array system with faulty elements can be increased by optimizing the remaining active elements in the array with the PSO method. It also reduces the cost of restoring and replacing the failed elements in an array regularly. This approach also prevents near-field measurement that requires complicated processes using costly equipment.

Collective dynamics support group drumming, reduce variability, and stabilize tempo drift

Humans are social animals who engage in a variety of collective activities requiring coordinated action. Among these, music is a defining and ancient aspect of human sociality. Social interaction has largely been studied in dyadic contexts. The presence of multiple agents engaged in the same task space creates different constraints and possibilities that have been studied more extensively in nonhuman animal behaviour. We addressed whether collective dynamics play a role in human circle drumming. The task was to synchronize in a group with an initial reference pattern and then maintain synchronization after it was muted. We varied the number of drummers, from solo to dyad, quartet, and octet. The observed lower variability, lack of speeding up, smoother individual dynamics, and leader-less inter-personal coordination indicated that stability increased as group size increased, a sort of temporal wisdom of crowds. We propose a hybrid continuous-discrete Kuramoto model for emergent group synchronization with pulse-based coupling that exhibits a mean field positive feedback loop. This research has theoretical implications about collective intentionality and social cognition.

Multiple functions of the inclusive: examining synchronic variation in light of diachronic shift in South-Central Trans-Himalayan

A few languages of the South-Central branch of Trans-Himalayan (Tibeto-Burman/Sino-Tibetan) display diachronic shifts of the inclusive to become innovative markers of 1sg or 2sg. Such shifts are rarely reported in the cross-linguistic literature. In conjunction with phylogenetic-comparative evidence on cases of actual diachronic shift, we offer a synchronic usage-based analysis of the inclusive in one particular language, Anal Naga. In this language, usage frequencies suggest that a shift of the inclusive is underway: apart from the frequent generic usage, the inclusive now commonly has a humbling, empathy-seeking first person (1sg/excl) reference. In contrast, forms that combine inclusive and plural marking pattern more like a prototypical inclusive, i.e., with regular reference to the local speech act participants of speaker and addressee(s). The optional plural marking is the most important factor to determine the reference pattern of the inclusive. Other factors (irrealis setting; lexeme semantics) only play a marginal role; person form (bound indexes or free pronouns) and syntactic role are not indicative.

Token-Based Authentication Framework for 5G MEC Mobile Networks

MEC technology provides a distributed computing environment in 5G mobile networks for application and service hosting. It allows customers with different requirements and professional competencies to use the services offered by external suppliers. We consider a service access control framework on 5G MEC networks that is efficient, flexible, and user-friendly. Its central element is the MEC Enabler, which handles AAA requests for stakeholders accessing services hosted on the edge servers. The JSON Web Token (JWT) open standard is a suitable tool for the MEC Enabler to manage access control credentials and transfer them securely between parties. In this paper, in the context of access control, we propose the token reference pattern called JSON MEC Access Token (JMAT) and analyze the effectiveness of its available protection methods in compliance with the standard requirements of MEC-hosted services in 5G networks.

Radiation Power Pattern Distortion Analysis Using MATLAB for MST Radar System

Most often, in MST radar system, a few number of transmitters are non-operational due to various factors, making the liner sub-arrays corresponding to these transmitters in effective. This results in the thinning of the aperture and deviation of the excitation from the specified Taylor distribution. The array pattern will be distorted due to this deviation, when compared to the reference pattern. This chapter gives a complete analysis to quantify the distortion in the radiation pattern due to Aperture thinning. MATLAB was extensively used to analyze the results. The results of the radiation pattern in both principal planed and for different azimuth angles with and without thinning/tilt are presented. Radiation pattern is viewed in both polar and rectangular (2-D and 3-D) forms. Conclusions on the results obtained are presented.

THE MANAGEMENT OF A TRAINING DEVELOPMENT STRATEGIES TO INCREASE THE COMPETITIVE ADVANTAGE OF LIFE LOCAL INSURANCE COMPANIES

This study aims to analyze the development of training management for employees and agents as well as a training roadmap model and human resource development in increasing competitive advantage in Local Life Insurance. The paradigm in the implementation of this research uses a qualitative phenomenological paradigm as a reference, pattern and framework that starts from empirical generalizations or empirical generalizations on the growth and development of social reality. ThisXresearchxuses qualitativexmethods with thextype ofXcaseXstudy research. Primary data were obtained from information and factual experiences of informants using structured interviews through In-depth interviews and focus group discussions. The results of the study found that this local life insurance company did not yet have training management and employee development. HRD is not able to formulate employee development patterns. This company needs to conduct a comprehensive evaluation of the occurrence of a vacancy in the management system for employee training and development. The results of the study also show management's neglect when there is a vacancy of the people development function by the company's HRD. Agency Training & Development already owns and implements Agent training management

Method for automatic evaluation of the voice signals quality with low bit rate voice coding

Evaluation of the VSQ is an important problem. In known methods for еvaluation the quality of analog or digital voice signals with pulse-code modulation (PCM) are used. When automatic quality assessing, it is assumed that the parameters of voice signal are determined. Then the corresponding subjective assessment of VSQ is selected. Objective methods for quality assessing are obtained by comparing the reference signal and the signal transmitted through the communication channel. To eliminate the identified contradictions, it is proposed to use an objective method that provides the assessing of VSQ in the absence of a reference signal and without conversion to the PCM format, i.e. based on the analysis of the LBR voice digital stream. The analyzed digital stream is considered as a system of random variables, which is characterized by a set of mean values and a covariance matrix that make up the pattern of input implementation. The reference pattern also includes a set of mean values and a covariance matrix. The initial data for the formation of a reference pattern are digital streams formed according to a given protocol of LBR voice coding, having the highest VSQ. The proposed method is based on calculating the divergence between the reference pattern and input implementation pattern. At the training stage, several distorted samples with a known number of bit errors are formed from the reference sample. When comparing their patterns, the divergence values are calculated, which are put in compliance with the VSQ assessment. Two approaches have been identified for making the compliance: experimental and experimental-analytical. The choice of approach is determined by the presence of initial data characterizing the VSQ for particular vocoder. Then generated compliance is interpolated. At the assessment stage for each implementation is calculated the divergence between the explored pattern and the reference pattern, which is formed from the training sample. Based on the divergence, the VSQ assessment is calculated. To test the proposed method a reference sample of digital streams obtained by compressing voice signals with a LPC-10-2400 vocoder was formed. Based on the initial data, which are presented in Recommendation-R F.1112-1, the compliance between the values of sound intelligibility and divergence was compiled by experimental-analytical approach. The obtained correspondence was interpolated by the least squares method using a third degree polynomial.