Channel Identification Research Articles

Statistical LOS/NLOS Classification for UWB Channels

Ultrawideband (UWB) technology has attracted a lot of attention for indoor and outdoor positioning systems due to its high accuracy and robustness in non-line-of-sight (NLOS) environments. However, UWB signals are affected by multipath propagation which causes errors in localization. To overcome this problem, researchers have proposed various techniques for NLOS identification and mitigation. One of the approaches is statistical LOS/NLOS classification, which uses statistical parameters of the received signal to distinguish between LOS and NLOS channels. In this paper, we formulated several techniques which can be used for effectively classifying Line of Sight (LOS) channel from a Non-Line of Sight (NLOS) channel. Various parameters obtained from Channel Impulse Response (CIR) like Skewness, Kurtosis, Root Mean Squared Delay Spread (RDS), Mean Excess Delay (MED), Energy, Energy Ratio and Mean of Covariance Matrix are used for channel classification. In addition to this, the Joint Probability Density Functions (PDFs) of various parameters are used to improve the accuracy of UWB LOS/NLOS channel classification. Two different criteria-Likelihood Ratio and Hypothesis Test are used for the identification of channel.

Level, structure and dynamics of drug trafficking

The subject of this study is the level, structure and dynamics of crimes in the field of illicit drug trafficking. Some indicators of official statistics related to the operational situation in the fight against drug trafficking in the country are considered (the number of registered crimes, identification and suppression of drug distribution channels, etc.). The purpose of the study is to conduct a detailed analysis of statistical data on crimes related to drug trafficking, identify current problems in the fight against drug crime and formulate proposals for eliminating them. General scientific methods of cognition were used: the method of statistical analysis; method of analysis, synthesis; comparative method; methods of induction, deduction. An analysis of scientific literature has shown that the issues of drug crime are studied in domestic doctrine by many authors. In theory, issues related to crime rates, the impact of illegal migration on the drug situation in Russia, and the problems of investigating drug crimes committed using information technologies have been worked out. However, some aspects require further study. Within the framework of this study, an attempt was made to identify from the entire array the most pressing problems that require a speedy solution. In particular, it is proposed to reconsider the issue of the availability of electronic devices (vapes, electronic cigarettes) used by adolescents and young people to use psychoactive substances. A ban on the use of such devices should be established at the legislative level. It is concluded that the fight against drug crime must be comprehensive and carried out at several levels, including the prevention of drug crimes among minors.

Spatial pattern of global submarine cable network and identification of strategic pivot and strategic channel

Spatial pattern of global submarine cable network and identification of strategic pivot and strategic channel

Supervised identification and equalization of transmission channel using reproducing kernel Hilbert space

The subject matter of the article is to identify and equalize the parameters of telecommunication channels. The goal is to develop a new mathematical approach based on positive definite kernels on a Hilbert space. The tasks to be solved are: (a) to formulate a mathematical procedure based on a kernel; a kernel is a function that maps pairs of data points to a scalar value, and positive definite kernels are widely used in machine learning and signal processing applications; (b) to identify the channel parameters using the proposed method; and (c) to apply the Zero Forcing and MMSE equalizer to measure the performance of the proposed system. This article introduces a new method to address the problem of supervised identification of transmission channel parameters based on the positive definite kernel on Hilbert space, which implements Gaussian kernels. The input sequence, used as an input for a system or process, is assumed to be independent, have a zero mean, a non-Gaussian distribution, and be identically distributed. These assumptions are made to simplify the analysis and modeling. The proposed method for estimating the parameters of the channel impulse response yields promising results, indicating that the estimated parameters are close to the measured parameters of the model for various channels. The convergence of the estimated parameters toward the measured parameters of the model is particularly noticeable for BRAN A (indoor) and BRAN E (outdoor) channels. The method has been tested with different channel models, and the results remain consistent. Overall, the proposed method appears to be a reliable and effective approach for estimating channel impulse response parameters. The accuracy of the estimated parameters is particularly noteworthy considering the challenges inherent in modeling wireless channels, which can be influenced by various factors such as obstacles and interference. These findings have important implications for the design and optimization of wireless communication systems. Accurate estimates of channel impulse response parameters are essential for predicting and mitigating the effects of channel distortion and interference, and the proposed method represents a promising tool for achieving this goal. Further research and testing are needed to validate and refine the method and to explore its potential applications in different settings and scenarios. We evaluated the performance of the system using the estimated parameters obtained from the proposed method. Two equalizers, MMSE and ZF, were used, and the results show that MMSE outperforms ZF. Both equalizers produced highly satisfactory outcomes.

Learning the right channel in multimodal imaging: automated experiment in piezoresponse force microscopy

We report the development and experimental implementation of the automated experiment workflows for the identification of the best predictive channel for a phenomenon of interest in spectroscopic measurements. The approach is based on the combination of ensembled deep kernel learning for probabilistic predictions and a basic reinforcement learning policy for channel selection. It allows the identification of which of the available observational channels, sampled sequentially, are most predictive of selected behaviors, and hence have the strongest correlations. We implement this approach for multimodal imaging in piezoresponse force microscopy (PFM), with the behaviors of interest manifesting in piezoresponse spectroscopy. We illustrate the best predictive channel for polarization-voltage hysteresis loop and frequency-voltage hysteresis loop areas is amplitude in the model samples. The same workflow and code are applicable for any multimodal imaging and local characterization methods.

THE ROMAN AQUEDUCT OF KNOSSOS, A MODEL FOR NINETEENTH-CENTURY AQUEDUCT DESIGN

In this paper, we present findings from a field inspection of the Knossos aqueduct undertaken in 2019. A key contribution of our fieldwork was the architectural identification of the Roman channel underlying the nineteenth-century wall of the Ottoman-Egyptian aqueduct supplying Iraklio. While reuse of the Roman aqueduct in the nineteenth century was known from historical reports, the structural overlap has never been identified in the field or documented archaeologically, until now. We recorded the Roman channel lined with opus signinum running along the base of the nineteenth-century aqueduct's wall between Fundana and Spilia. Through this realisation in the field, we were able to establish diagnostic styles of masonry for both periods. Our architectural distinction between the overlaid aqueducts allowed us to integrate previously disarticulated components of the later system, like the reused Roman tunnel at Skalani and the nineteenth-century bridge at Spilia, into an integrated Ottoman-Egyptian water supply for Iraklio. As we approached Knossos from Spilia, we were also able to identify the point at which the Venetian aqueduct supplying Iraklio converged with the Roman system. Consequently, our 2019 fieldwork not only mapped the length of the Roman aqueduct supplying the city of Knossos but also that section of the nineteenth-century Ottoman-Egyptian aqueduct of Iraklio built directly over it and a shorter tract of the Venetian aqueduct of Iraklio that either ran alongside it or was, in turn, itself partially overlaid by the nineteenth-century system.

Brain–computer interface in an inter-individual approach using spatial coherence: Identification of better channels and tests repetition using auditory selective attention

Auditory Brain–Computer Interfaces (BCIs) have been studied with the main purpose of improving the quality of life of totally paralyzed people. BCIs based on Auditory Selective Attention (ASA) may have distinct features, such as the number of sound sources and most approaches presented in literature use individualized settings. This setup requires more training of individuals or adjustments of the internal classifiers. In this context, a generalized approach can be an interesting alternative for an interface tailored to application and without the need for exhaustive training. The present work investigates ASA using stimuli with AM modulation and spatial coherence to evaluate its value in the modulating frequency and the electrodes position. The objective is to identify better combinations of electrodes and evaluate the number of repetitions and the intervals between them in an inter-individual approach. The best result obtained using the modular classifier, proposed in an earlier work, reached average hit rates of 75% and information transfer rate (ITR) of 2.217 bits/min, considering three windows (5.1 s). This result was obtained using AM stimuli (500 Hz and 2 kHz carriers) and a combination of mostly frontal and prefrontal electrodes and considering 5 s interval between repetitions. With these results, an implementation of a vision-free BCI that covers inter-individual differences could allow users to communicate through selective auditory attention without previous training of subjects.

Intermediate conductance Ca2+-activated potassium channels are activated by functional coupling with stretch-activated nonselective cation channels in cricket myocytes.

Cooperative gating of localized ion channels ranges from fine-tuning excitation-contraction coupling in muscle cells to controlling pace-making activity in the heart. Membrane deformation resulting from muscle contraction activates stretch-activated (SA) cation channels. The subsequent Ca2+ influx activates spatially localized Ca2+-sensitive K+ channels to fine-tune spontaneous muscle contraction. To characterize endogenously expressed intermediate conductance Ca2+-activated potassium (IK) channels and assess the functional relevance of the extracellular Ca2+ source leading to IK channel activity, we performed patch-clamp techniques on cricket oviduct myocytes and recorded single-channel data. In this study, we first investigated the identification of IK channels that could be distinguished from endogenously expressed large-conductance Ca2+-activated potassium (BK) channels by adding extracellular Ba2+. The single-channel conductance of the IK channel was 62 pS, and its activity increased with increasing intracellular Ca2+ concentration but was not voltage-dependent. These results indicated that IK channels are endogenously expressed in cricket oviduct myocytes. Second, the Ca2+ influx pathway that activates the IK channel was investigated. The absence of extracellular Ca2+ or the presence of Gd3+ abolished the activity of IK channels. Finally, we investigated the proximity between SA and IK channels. The removal of extracellular Ca2+, administration of Ca2+ to the microscopic region in a pipette, and application of membrane stretching stimulation increased SA channel activity, followed by IK channel activity. Membrane stretch-induced SA and IK channel activity were positively correlated. However, the emergence of IK channel activity and its increase in response to membrane mechanical stretch was not observed without Ca2+ in the pipette. These results strongly suggest that IK channels are endogenously expressed in cricket oviduct myocytes and that IK channel activity is regulated by neighboring SA channel activity. In conclusion, functional coupling between SA and IK channels may underlie the molecular basis of spontaneous rhythmic contractions.

Generic method to assess transmutation feasibility for nuclear waste treatment and application to irradiated graphite

Graphite-moderated nuclear reactors have already produced more than 250,000 tons of irradiated nuclear graphite, or i-graphite, world-wide. The sustainability of this technology relies on the end-of-life management of its moderator, which is activated into a long-lived, low or intermediate-level nuclear waste, by neutron fluxes, during operating time. In particular, carbon-14 is created. Nuclear transmutation, enabled by laser-driven particle acceleration, has been envisioned as a potential novel treatment scheme for long-lived nuclear waste. By triggering controlled nuclear reactions with energetic particles, long-lived radio-nuclides could be transformed into short-lived or stable isotopes. Such a system could treat the carbon-14 nuclei trapped within the i-graphite matrix, an isotope which is difficult to isolate by other means. This work performs a quantitative preliminary study of this transmutation scheme, in order to assess its feasibility at an industrial scale. The method used can be transposed to assess any transmutation scheme using a beam of particles directly sent on the material to be treated. First, a nuclear interaction channel which transmutes carbon-14 nuclei without creating new long-lived radio-nuclides is identified. It consists in the choice of a type of particle, among which protons, γ photons and neutrons can all be accelerated by laser–matter interaction; and it is completed by the adequate energy at which this particle must be sent on i-graphite. To that end, the nuclear cross-sections of carbon-12, carbon-13 and carbon-14 are reviewed, neglecting other impurities in i-graphite. Then, based on the interaction channel identification, the energy cost of this scheme is estimated. Protons between 1 and 5MeV make it possible to transmute carbon-14 without creating any new long-lived activity. However, our result show that, even in this favourable reaction channel, the transmutation energy cost is too high for an i-graphite transmutation scheme to be industrially feasible.

Impact of PIEZO1-channel on inflammation and osteoclastogenesis mediated via periodontal ligament fibroblasts during mechanical loading.

The identification of mechanosensitive ion channels and their importance in innate immunity provides new starting points to elucidate the molecular mechanisms of orthodontic tooth movement. The mechanosensitive electron channel PIEZO1 (Piezo Type Mechanosensitive Ion Channel Component 1) may play a crucial role in orthodontic tooth movement. To investigate the role of the PIEZO1 channel, periodontal ligament fibroblasts (PDLF) were subsequently treated with a PIEZO1 inhibitor (GsMTx) with simultaneous pressure application or with an activator (JEDI2) without mechanical strain. The expression of genes and proteins involved in orthodontic tooth movement was examined by RT-qPCR, Western blot and ELISA. In addition, the effect on PDLF-mediated osteoclastogenesis was investigated in a coculture model using human monocytes. Inhibition of PIEZO1 under pressure application caused a reduction in RANKL (receptor activator of NF-kB ligand) expression, resulting in decreased osteoclastogenesis. On the other hand, activation of PIEZO1 without mechanical strain downregulated OPG (osteoprotegerin), resulting in increased osteoclastogenesis. PIEZO1 appears to play a role in the induction of inflammatory genes. It was also shown to influence osteoclastogenesis.

Identification of Water Flooding Advantage Seepage Channels Based on Meta-Learning

As the water injection oilfield enters into the high water cut stage, a large number of water flooding advantage seepage channels are formed in the local reservoir dynamically changing with the water injection process, which seriously affects the water injection development effect. In oilfield production, water injection and fluid production profile test data are direct evidence to identify advantage seepage channels. In recent years, some scholars have carried out research related to the identification of advantage seepage channels based on machine learning methods; however, the insufficient profile test data limit the quantity and quality of learning samples, leading to problems such as low prediction accuracy of learning models. Therefore, the author proposes a new method of advantage seepage channel identification based on meta-learning techniques, using the MAML algorithm to optimize the neural network model so that the model can still perform well in the face of training tasks with low data sample size and low data quality. Finally, the model was applied to the actual blocks in the field to identify the advantage seepage channels, and the identification results were basically consistent with the tracer monitoring results, which confirmed the feasibility of the method. It provides a new solution idea for the task of identifying advantage seepage channels and other tasks with low data quality, which has a certain guiding significance.

High-density Approaches to Ventricular Tachycardia Substrate Ablation

Ventricular tachycardia (VT) ablation is a challenging procedure with significant clinical benefit for patients. The classic VT ablation approach centers on arrhythmia induction and entrainment of tachycardia to identify the critical components of a VT circuit. In the post-coronary reperfusion era, smaller infarct size and subsequently faster VT cycle lengths have led to an increased occurrence of unstable, unmappable VT cases, making the classic approach untenable. While approaches of signal-based substrate modification have shown clinical efficacy in the past, these approaches are sometimes imprecise and require extensive ablation. With the advancement of high-density (HD) mapping technology and recognition of functional tissue properties requisite for VT initiation and propagation, a more finely targeted VT ablation approach may be pursued. Benefits of HD mapping include better tissue and signal characterization, avoidance of ‘perpendicular blinding’ and better identification of VT putative channels. Functional characterization of tissue, such as isochronal late activation mapping or decremental evoked potential mapping, allow for the identification of functional slowing required for VT reentry. Pre-ablative imaging continues to play an increasing role in substrate characterization and pre-operative planning. Using a comprehensive, tailored, substrate-based functional HD VT ablation strategy can allow for safe and effective ablation of even unstable and unmappable VT.

Management of large post-crossover inguinal lymphocele

A 73-year-old man with a history of peripheral arterial disease and previous bilateral common femoral artery reconstruction presented with left foot critical limb-threatening ischaemia and underwent right to left femoro-profunda crossover grafting. Postoperatively, he developed a left groin lymph leak that initially dried up but later re-presented as a very large lymphocele. Initial attempts with aspiration on three occasions and then surgical drainage with sac excision and ligation of long saphenous lymphatics did not lead to resolution. Subsequently, a hybrid approach using percutaneous lymphangiography and drainage, sclerotherapy (bleomycin, then absolute alcohol) and eventual identification and ligation of the afferent lymphatic channel resulted in resolution of the lymphocele without untoward side effects, sepsis or compromise of the revascularisation.

ХУДОЖЕСТВЕННЫЙ КОНЦЕПТ NATURE В АСПЕКТЕ ЛИНГВОСЕНСОРИКИ: АКТУАЛИЗАЦИЯ ЭМОТИВНОГО СМЫСЛА

The article deals with the linguistic representation of nature perception. The aim of the research is to identify the emotive meaning transmitted in fiction and to reveal the role of the concept NATURE in the construction of the plot line. The novelty of the research consists in the complex methodological approach based on semantic, pragmatic, contextual, cognitive and discursive analysis. The research methodology includes analysing the situations of visual, olfactory, audial, tactile, and gustatory perception, the identification of dominant channels of nature perception, the description of the emotivity, the investigation of the role of the NATURE concept in the development of the plot. The study reveals cases of consonant and dissonant interaction between the evaluative interpretation of nature and the emotional state of characters and the phenomenon of emotional-evaluative resonance. The research has shown the possibility of singling out the discourse-forming function of the literary concept NATURE, which is conditioned by its significance in the construction of the storyline and the actualization of the emotive meaning. The results of the research may be used in the works on discourse analysis, in pragmatic and cognitive researches of fiction discourse.

Bifurcated Arc of Buhler Co-existent with an Arc of Riolan-A Rare Case Report

The Arcs of Buhler and Riolan are collateral channels that connect the major midline ventral branches of the abdominal aorta, which supply the gastrointestinal tract. These arcs occur with a relative rarity of 1-10%. During routine dissection of the abdominal cavity of a 50-year-old, embalmed male Indian cadaver in the Department of Anatomy of a National Institute in South India, the presence of a large vertical tortuous bifurcated artery was noticed, posterior to the body of the pancreas, connecting the coeliac trunk to the superior mesenteric artery. This was identified to be an Arc of Buhler (AOB) and measuring 8 mm in external diameter. In addition, an Arc of Riolan (AOR) was identified, connecting the left division of the Buhler’s arc to the left colic artery. The presence of a large bifurcated AOB or its co-existence with an AOR has not been described previously. The identification of such anastomotic channels in symptomatic patients may help in diagnosing impending bowel ischemia. Aneurysms of AOB, though rare, are life-threatening and have been treated successfully. The knowledge of mesenteric vascular anatomy is important during abdominal surgeries and endovascular procedures. Recognising a vascular variation is crucial to avoid inadvertent bleeding or bowel ischaemia.

Economic aspects of state support of Russian steel industry enterprises in the conditions of external shocks

The metallurgical sector of Russia has been a recipient of state support at the federal and regional levels for many years. The sector receives subsidies from more than 90 programs and indirectly benefits from pricing policies for electricity, natural gas and rail transport. However, the analysis of measures to support the sector under the conditions of Western sanctions and the coronavirus pandemic is of particular relevance. The aim of the work is to determine the role of state support for steel producers in the face of external shocks — the coronavirus pandemic and Western sanctions. The working hypothesis of the study is the assertion that direct and indirect measures related to supporting the sector in the face of sanctions and the negative consequences of coronavirus contribute to reducing the adaptation costs of producers, as well as increasing their competitiveness. The stated goal and the indicated hypothesis determine the structure of the paper. Thus, the author examines the theoretical and practical aspects of the impact of sanctions on the national economy, the Russian steel market, state policy towards the steel industry, as well as direct and indirect measures of state assistance that affect the steel production sector. The research methodology is based on a comprehensive review of indirect and direct mechanisms of state support for the industry. The study resulted in the identification of channels of state influence on the steel market in the context of the COVID-19 pandemic and sanctions. The results of the study can be used in the formation of the Russian industrial policy.

Interfering reaction channels observed in the 2H(8He,4He)6H reaction studies

In the recent work [Nikolskii et al., Phys. Rev. C 105, 064605 (2022)] the 2H(8He,4He)6H reaction was used for the study of the extreme neutron-rich 6H isotope. A broad bump was observed in the measured 6H spectrum interpreted as the broad overlapping ground and some low-lying states of this nuclide. There could be certain doubts in the interpretation of this work: in conditions of the limited phase space it is not impossible that the structure in the missing mass spectrum of 6H is actually induced by the resonant states populated by some other channels opened in the 8He+2H interaction. This work provides a body of the evidence for the correct channel identification and for the absence of the 6H resonances at energy ET = 0 − 3.5 MeV above the 3H+3n decay threshold. In addition the first strong experimental evidence is given that the 6H → 5H*+n → 3H+3n sequential decay is the dominating 6H decay channel.

A feedforward and feedback composite active noise reduction headset based on inverse filter frequency equalization and its DSP system implementation

The principle of active noise reduction headset is to reduce the original noise by generating inverted noise through the loudspeaker. The loudspeaker system will introduce spectrum distortion inevitably. This distortion will increase the complexity of the secondary channel model, which adversely affect identification of the primary channel in the real-time active noise reduction system. To improve the inherent frequency spectrum distortion of the speaker system, this paper proposes a new frequency equalization method based on inverse filtering. This method is applied to a feedforward and feedback compound active noise reduction earphone system, and a new active noise reduction headphone system is obtained. In order to improve the noise reduction effect, the pollution caused by the secondary sound source to the reference signal is compensated in the active noise reduction control scheme of this paper. Simulation and real-time noise reduction experiments based on DSP solution show that this new active noise reduction control system can achieve better noise reduction effects.

Modifying Knowledge Risk Strategy Using Threat Lessons Learned from COVID-19 in 2020-21 in the United States

2020 and 2021 have shown us that the likelihood of extreme events is more significant than we would have expected. Due to extreme circumstances, organizational resources are stretched to their limits, making organizations more vulnerable to attacks affecting their knowledge systems and knowledge assets. This paper conducts an intelligence-based threat assessment by analyzing published reports on events during the 2020-21 period against a set of five knowledge risks to identify threats and determine if they increase the likelihood of these risks occurring. We identify six possible changes in knowledge risk strategy to mitigate these threats: proper knowledge identification, guidelines for employee online behavior, identification and evaluation of online communication channels, re-evaluation of how work is to be performed, creation of knowledge capture processes for departing personnel, and performing a knowledge risk re-assessment. Additionally, we conclude that organizations need expertise in identifying and countering misinformation and disinformation to defend themselves from these new cyber threats.

Recursive adaptive filtering algorithms for sparse channel identification and acoustic noise reduction

Recursive adaptive filtering algorithms for sparse channel identification and acoustic noise reduction