Channel Behavior Research Articles

Secure Communications Based on Cognitive Multidisciplinary Strategies

The use of cognitive multidisciplinary strategies represents a powerful tool to allow a communication system to transmit and receive data in a secure way by working in parallel with other electromagnetic devices, sharing the same frequency channels, without being affected by malfunctions caused by unintentional or intentional interferences (e.g. jammers). The cognitive operation is possible by modeling the channel behavior and predicting future channel occupancy. The model of the electromagnetic environment is based on the observation of the spectrum occupancy over time and on suitable reinforced learning strategies to acquire the characteristics of the channel occupancy. The learning operation is paramount, as the prediction about channel occupancy is possible only after understanding the behavior of the concurrent emitters present in the scenario. This paper describes the concept of reinforced learning techniques, based on emitter classification and matching and on human in the loop agent. implemented on a number of real cases of emitter behavior. We show that, in selected study cases, our reinforced learning techniques based on cognitive multidisciplinary strategies can provide good performance, even in presence of a consistent number of concurrent transmitters.

Numerical simulation of subcooled boiling considering bubble sliding behavior in conventional channels

Subcooled boiling has a strong heat transfer capacity, and its heat transfer effect is closely related to the dynamic behavior of bubbles. Many researchers have discovered the bubble sliding behavior in subcooled boiling, which disrupts the thermal boundary layer and thus enhances the heat transfer capacity. This phenomenon occurs not only in narrow channels, but also in conventional channels. In this paper, the wall boiling model including the effect of the sliding bubbles and the nucleation sites density model with a wider application range. The bubble diameter is calculated from the force balance model and coupled into the wall boiling model. On the basis of verifying the accuracy of the model, the variation trend of bubble diameter, nucleation sites density and the relative contribution of each part of wall heat flux along the heating channel and the influence of different working conditions are analyzed. Under different working conditions, the calculated results are in good agreement with most of the experimental data, the error of 90% of the void fraction data is within 25%. In addition, the numerical results show that the relative contribution of bubble sliding quenching heat flux can up to 65%, so the effect of sliding bubbles on the relative contribution of each part of wall heat flux cannot be ignored. Different working conditions indirectly affect the heat flux of each part through the nucleation sites density and the diameter of the bubble.

Practical Approaches for Providing Empirical Data on Seabird Behavior and Prey Assemblages in Tidal Channels

Persisting knowledge gaps relating to the ecological context and potential environmental impacts of marine renewable energy (MRE) devices continue to add substantial costs and uncertainty to MRE projects globally. Increasingly sophisticated technological approaches to environmental monitoring can have fundamental non-trivial shortcomings for environmental impact assessment (EIA), whilst substantial practical and financial costs of deployments can prevent their application. For the tidal stream energy (TSE) sector, there is a need for practical and cost-effective methods that can provide site-specific information on predator behavior and associated prey assemblages. Considering existing knowledge of animal communities in tidal channel environments, a proportional approach using shore-based observation and baited fish trap methods was developed. During April 2021, a trial of these methods was conducted in tidal channel environments in Shetland, UK. The practical application of the proposed approach is demonstrated here with results from three tidal channels including Bluemull Sound, the site of active TSE installations (the Shetland Tidal Array). Observation of predator behavior across the study sites are reported for great cormorant Phalacrocorax carbo and European shag Phalacrocorax aristotelis. Seabird diving data calculated from the shore-based observations provided metrics relevant to informing EIA and collision risk modelling including dive duration, dives per minute, and % time underwater. Fish trap deployments targeted the benthic and demersal prey of these predators in the three study sites and across a range of depths and hydrodynamic conditions. A variety of fish and invertebrate species known to be important components of benthic-foraging seabird diet were successfully captured by the traps, providing basic biological information on the prey assemblages observed in each site. The fish species observed in the highest abundance were saithe Pollachius virens and cod Gadus morhua. Benefits, limitations, and applications of this approach are discussed along with various factors relating to the performance of both methods. The shore-based observations rapidly identified relevant patterns in predator foraging activity which informed the targeted deployment of fish traps to provide complementary prey data. This novel combined approach has potential to reduce costs and uncertainty in EIA and for supporting the responsible development of the MRE industry.

Implementation of Block-Level Double Encryption Based on Machine Learning Techniques for Attack Detection and Prevention

Cloud computing is one of the most important business models of modern information technology. It provides a minimum of various services to the user interaction and low cost (hardware and software). Cloud services are based on the newline architectures on virtualization by using the multitenancy for better resource management and newline strong isolation between several virtual machines (VMs). The spying on a victim VM is challenging, particularly when one wants to use per-core microarchitectural features as a side channel. For example, the cache contains the most potential for damaging side channels, but shared information across different cores affects the cloud information. To overcome this problem, propose the Secure Block-Level Double Encryption (SBLDE) algorithm for user signature verification in the cloud server. It uses identity-based detection techniques to monitor the colocated VMs to identify abnormal cache data and channel behaviors typically during VM data transformation. The identity-based linear classification (IBLC) method is used for classifying the attacker channel when the data is transferred/retrieved from the VM cloud server. This cloud controller finds the channel misbehavior to block the port or channel, changing other available ports’ communication. The service verification provides strong user access permission on the cloud server when the unknown request to the cloud server suddenly executes the key authentication to verify the user permission. This linear classification trains the existing side-channel attack datasets to the classifier and identifies the VM cloud’s attack channel. The study focused on preventing attacks from interrupting the system and serves as an effective means for cross-VM side-channel attacks. This proposed method protects the cloud data and prevents cross-VM channel attack detection efficiently, compared to other existing methods. In this overall proposed method, SBLDE’s performance is to be evaluated and then compared with the existing method.

Designing doping strategy in arsenene monolayer for spintronic and optoelectronic applications: a case study of germanium and nitrogen as dopants

In this work, the structural, electronic, and magnetic properties of arsenene monolayer doped with germanium (Ge) and nitrogen (N) atoms are investigated using density functional theory calculations. Pristine monolayer is dynamically stable and it possesses a wide indirect band gap. Ge doping induces magnetic semiconductor (MS) nature generated by the semiconductor behavior in both spin channels with significant spin asymmetry around the Fermi level. The dopant produces mainly magnetic properties. Upon increasing the doping concentration, different doping configurations along armchair, zigzag edges, and hexagonal ring have been proposed. The MS nature is retained with an odd number of Ge atoms, meanwhile an eVen number leads to the disappearance of magnetism. In contrast, N doping induces a gap reduction of 11.80%, preserving the non-magnetic nature. At higher doping level, different electronic features including semiconductor, nearly semimetallic, and metallic natures are obtained depending on the doping concentration and configurations. In addition, the formation energy and cohesive energy are calculated to analyze the systems’ stability. Our results show that different doping arrangements induce novel features in arsenene monolayer for applications in spintronic and optoelectronic devices.

Effect of web perforations on end-two-flange web crippling behaviour of roll-formed aluminium alloy unlipped channels through experimental test, numerical simulation and deep learning

Aluminium alloy has recently become popular in New Zealand’s construction sector as a sustainable building material. However, in roll-formed aluminium alloy (RFA) channel beams, particularly those having web holes, cripples at points of concentrated or localised loading. In this paper, end-two-flange (ETF) web crippling behaviour of RFA unlipped channels having web holes was investigated using experimental tests, numerical simulations and a deep learning model referred as deep belief network (DBN). A total of 1080 data points was generated to train the DBN, using a finite element (FE) model that was validated using 30 new experimental results reported in this paper. Compared to the test data, the DBN predictions were conservative by around 6%. Using the DBN predictions, a comprehensive parametric study was undertaken which used the validated FE model in order to explore the effects of hole size, hole location, section thickness, and bearing plate on the web crippling strength of RFA channels having web holes. Web crippling strengths obtained from the DBN, tests and finite element analysis (FEA) were utilised to evaluate the performance of current design specifications from the American Iron and Steel Institute (AISI), Australian/New Zealand Standards (AS/NZS 1664; AS/NZS 4600:2018) and Eurocode (CEN 2006, 2007). It is shown that the current design rules are not reliable to predict the web crippling strength of RFA unlipped channels with web holes. As a consequence of the parametric analysis, new web crippling strength and web crippling strength reduction factor formulae for perforated RFA unlipped channels were proposed. A reliability analysis was then conducted, which confirmed that the proposed equations are capable of predicting the ETF web crippling strength of perforated RFA unlipped channels.

A procedure for estimating the absolute potential difference across metal|water interfaces: A reassessment

The estimate of the absolute potential difference across metal|aqueous solution (M|W) interfaces is of paramount importance to compare the behavior of ion channels incorporated in metal-supported biomimetic membranes with that in biomembranes and, most importantly, to obtain further behavioral information by the use of surface sensitive techniques. In 2011 Guidelli and Becucci described a procedure based on the use of a thiolipid called DPTL, consisting of a tetraethyleneoxy (TEO) hydrophilic chain terminated at one end with a lipoic acid residue, for anchoring to the mercury surface, and covalently linked at the other end to two phytanyl chains mimicking the hydrocarbon tails of a phospholipid. DPTL has been widely employed to fabricate metal supported tethered bilayer lipid membranes (tBLMs) by anchoring it to the metal surface of Hg, Au, and Ag. The above procedure relies on an independent estimate of the surface dipole potential χTEO of the TEO chain tethered to Hg and on the reasonable assumption that it remains unaltered when tethered to other metals. The present note corrects an erroneous estimate of the absolute potential difference across a polycrystalline Au|W interface in the 2011 paper, provides a clearer explanation of the procedure using the concept of electrochemical potential of electrons, estimates the absolute potential difference across the Au(111)|W interface, and compares the results of the proposed procedure with Trasatti’s ‘interfacial term’.

ANN-based LoRaWAN Channel Propagation Model

LoRaWAN wireless communication channels are often impacted by noise and interference over long-range causing loss of a received signal. One of the main drawbacks of using existing propagation models is less accurate as these models in designing the communication link are tailored to simplify the estimation. In this paper, an artificial intelligent real time path loss model is proposed. It is capable of processing complex variables over a short period of time. Providing it with enough data, the model is able to learn channel behavior and predict the path loss accurately. Results of the model are benchmarked against classical statistical curve fitting models where RMSE values are also compared and indicating that the artificial intelligent model has better accurate prediction.

Terahertz Band Communication: An Old Problem Revisited and Research Directions for the Next Decade

Terahertz (THz) band communications are envisioned as a key technology for 6G and Beyond. As a fundamental wireless infrastructure, THz communication can boost abundant promising applications. In 2014, our team published two comprehensive roadmaps for the development and progress of THz communication networks, which helped the research community to start research on this subject afterwards. The topic of THz communications became very important and appealing to the research community due to 6G wireless systems design and development in recent years. Many papers are getting published covering different aspects of wireless systems using the THz band. With this paper, our aim is looking back to the last decade and revisiting the old problems and pointing out what has been achieved in the research community so far. Furthermore, in this paper, open challenges and new research directions still to be investigated for the THz band communication systems are presented, by covering diverse topics ranging from devices, channel behavior, communication and networking, to physical testbeds and demonstration systems. The key aspects presented in this paper will enable THz communications as a pillar of 6G and Beyond wireless systems in the next decade.

Deep Neural Network: An Alternative to Traditional Channel Estimators in Massive MIMO Systems

Fifth-generation (5G) requires a highly accurate estimate of the channel state information (CSI) to exploit the benefits of massive multiple-input-multiple-output (MaMIMO) systems. 5G systems use pilot sequences to estimate channel behaviour using traditional methods like least squares (LS), or minimum mean square error (MMSE) estimation. However, traditional methods do not always obtain reliable estimations: LS exhibits a poor estimation when inadequate channel conditions (i.e., low- signal-to-noise ratio (SNR) region) and MMSE requires prior statistical knowledge of the channel and noise (complex to implement in practice). We present a deep learning framework based on deep neural networks (DNNs) for fifth-generation (5G) MaMIMO channel estimation. After a first preliminary scheme with which we verify the good estimation capacity of our DNN-based approach, we propose two different models, which differ in the information processed by the DNN and benefit from lower computational complexity or greater flexibility for any reference signal pattern, respectively. The results show that, compared to the LS-based channel estimation, the DNN approach decreases the mean square error (MSE) and the system’s spectral efficiency (SE) increases, especially in the low- SNR region. Our approach provides results close to optimal MMSE estimation but benefits from not requiring any prior channel statistics information.

The involvement of CYP1A2 in biodegradation of dioxins in pigs.

2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is one of the most harmful chemicals showing resistance to biodegradation. The majority of TCDD effects is mediated by the aryl hydrocarbon receptor (AhR) pathway. TCDD binding to AhR results in the activation of cytochrome P450 enzymes (CYP1A1, CYP1A2, CYP1B1) involved in dioxin biodegradation. The goal of the study was to explore the potential role of CYP1A2 in the metabolism of TCDD. We investigated a molecular structure of CYP1A2 and the binding selectivity and affinity between the pig CYP1A2 and: 1/ DiCDD or TCDD (dioxins differing in toxicity and biodegradability) or 2/ their selected metabolites. pCYP1A2 demonstrated higher affinity towards DiCDD and TCDD than other pCYP1 enzymes. All dioxin-pCYP1A2 complexes were found to be stabilized by hydrophobic interactions. The calculated distances between the heme oxygen and the dioxin carbon nearest to the oxygen, reflecting the hydroxylating potential of CYP1A2, were higher than in other pCYP1 enzymes. The distances between the heme iron and the nearest dioxin carbon exceeded 5 Å, a distance sufficient to allow the metabolites to leave the active site. However, the molecular dynamics simulations revealed that two access channels of CYP1A2 were closed upon binding the majority of the examined dioxins. Moreover, the binding of dioxin metabolites did not promote opening of channel S–an exit for hydroxylated products. It appears that the undesired changes in the behavior of access channels prevail over the hydroxylating potential of CYP1A2 towards TCDD and the favorable distances, ultimately trapping the metabolites at the enzyme’s active site.

Fabrication of Irregularity-Free, Highly Circular Cross-Sectional Microchannel

Microchannels typically have rectangular cross-sections, whereas biological channels, such as blood vessels and airways, have circular cross-sections. The difference in cross-sections causes different fluidic behaviors, resulting in differences between fluidic behavior in microchannels and biological channels. To simulate fluidic behavior in vitro, circular cross-sectional microchannels are required. We developed a circular cross-sectional microchannel with a smooth channel wall, free from cracks and irregularities. In the fabrication process of the circular cross-sectional microchannel, uncured polydimethylsiloxane (PDMS) was inserted into a rectangular cross-sectional microchannel. Then, the PDMS was pushed out by the introduction of compressed air before the curing process. During the introduction of compressed air, we observed the behavior of the uncured PDMS and found the formation and movement of protrusions along the microchannel. After pushing out the uncured PDMS, the residual PDMS was cured, resulting in a circular cross-sectional microchannel. The fabrication method was examined by varying the channel orientation and airflow direction. In the case of the horizontal orientation and airflow in an opposite direction, the circularity of the microchannel was greater than 0.99 at the centimeter scale in all cross-sections along the microchannel.

Assessment of dam-induced changes in ecogeomorphological behaviour and fluvial functionality in the Damodar River, West Bengal, India

Abstract Anthropogenic interventions in the form of dams and barrages often alter the fluvial functionality and eco-geomorphological (geomorphology, hydrology, and ecology) behaviour of river systems. The present work examines the environmental flow, channel metamorphosis, and fluvial functionality of the Damodar River in the context of Damodar Valley Corporation (DVC) dams and development. Structural (dams, barrages, weirs, etc.) and non-structural (urban–industrial and agricultural disposal with effluents, sand mining, etc.) interventions hinder the ecological functionality of the river. This study portrays that the eco-geomorphological behaviour and fluvial functionality of the river have changed due to flow alteration and diversion by dams and barrages and due to rapid urban–industrial and agricultural growth in the basin area. These changes have affected riverine ecological integrity. The ecological functionality level of this study area ranges from 85 to 181, i.e. from poor to good–fair. The ecological functionality level in the sample channel sections (i.e., the immediate upstream and downstream of the Durgapur Barrage) is poor, and the value ranges from 61 to 100 due to the hydrological impact of the barrage and the Durgapur urban–industrial belt. This assessment work will help to restore the fluvial environment for humans as well as riverine biota. HIGHLIGHTS Dams and barrages have altered the hydrological flow regimes, affecting the eco-geomorphological behaviour of alluvial channels. Dam-induced fluvial metamorphosis is evident in the channel morphological parameters and channel classification. The fluvial functionality index has been applied to evaluate the ecological functionality level for the restoration of the riverine environment.

Challenges and vision of wireless optical and acoustic communication in underwater environment

SummaryUnderwater Wireless Communication is a rapidly growing technology in the research domain. The researchers have been working towards the developments in underwater communication by investigating climatic changes, prediction of natural disasters, marine environment, monitoring aquatic life, oceanographic transmission, and data collection. The main objective of underwater communication is to achieve lossless, high transmission with the least power consumption. The Unmanned Underwater Vehicles (UUVs) and Autonomous Underwater Vehicles (AUVs) are set up with remote instruments and sensors to enable the natural exploration of the resources in the undersea environment. This research article is based on the study of various modes of communication, architectures, and protocol layers involved in underwater communication. Furthermore, an underwater hybrid connection is established by opto‐acoustic signals, and the overview of various performance characteristics, channel behaviors, and issues in the underwater scenario are investigated.

Hybrid Route Optimisation for Maximum Air to Ground Channel Quality

The urban air mobility market is expected to grow constantly due to the increased interest in new forms of transportation. Managing aerial vehicles fleets, dependent on rising technologies such as artificial intelligence and automated ground control stations, will require a solid and uninterrupted connection to complete their trajectories. A path planner based on evolutionary algorithms to find the most suitable route has been previously proposed by the authors. Herein, we propose using particle swarm and hybrid optimisation algorithms instead of evolutionary algorithms in this work. The goal of speeding the route planning process and reducing computational costs is achieved using particle swarm and direct search algorithms. This improved path planner efficiently explores the search space and proposes a trajectory according to its predetermined goals: maximum air-to-ground quality, availability, and flight time. The proposal is tested in different situations, including diverse terrain conditions for various channel behaviours and no-fly zones.

End-to-End Learning of a Constellation Shape Robust to Channel Condition Uncertainties

Vendor interoperability is one of the desired future characteristics of optical networks. This means that the transmission system needs to support a variety of hardware with different components, leading to system uncertainties throughout the network. For example, uncertainties in signal-to-noise ratio and laser linewidth can negatively affect the quality of transmission within an optical network due to e.g. mis-parametrization of the transceiver signal processing algorithms. In this paper, we propose to geometrically optimize a constellation shape that is robust to uncertainties in the channel conditions by utilizing end-to-end learning. In the optimization step, the channel model includes additive noise and residual phase noise. In the testing step, the channel model consists of laser phase noise, additive noise and blind phase search as the carrier phase recovery algorithm. Two noise models are considered for the additive noise: white Gaussian noise and nonlinear interference noise model for fiber nonlinearities. The latter models the behavior of an optical fiber channel more accurately because it considers the nonlinear effects of the optical fiber. For this model, the uncertainty in the signal-to-noise ratio can be divided between amplifier noise figures and launch power variations. For both noise models, our results indicate that the learned constellations are more robust to the uncertainties in channel conditions compared to a standard constellation scheme such as quadrature amplitude modulation and standard geometric constellation shaping techniques.

Experimental study on the characteristics of multimerging pedestrians through macroscopic and microscopic analysis

Pedestrian merging behavior is one of the most frequently observed complex pedestrian behaviors and has a certain limited impact on evacuation efficiency in emergency situations. However, experimental research on the multiple merging behavior of pedestrians is very limited. To explore the macroscopic and microscopic characteristics of multiple-merging under special-angle conditions, this paper studies the pedestrian behavior of the main channel and branches in multiple-merging behavior, and analyzes the microscopic and macroscopic characteristics of pedestrians in the case of multiple merging. The width of the main channel is fixed at 2.4[Formula: see text]m, the angle between the branches and the main channel is 30, and the change in the width of the merging branches is 0.8, 1.2 and 1.6[Formula: see text]m. A total of 171 volunteers participated in the experiment, and UWB equipment was used to extract pedestrian trajectories. Obvious lanes were formed during the experiment, and there were obvious ramps. The density of the double branches is significantly higher than that of the single branch, and the maximum saturation value can reach 3.75[Formula: see text]ped/m2. When the width of the branch becomes narrower, the branch entrance and the main channel block each other. When the width of the branch is narrow enough, the influence of the number of branches on the speed of the branch is reduced. When the number of branches increases, to make the distribution of pedestrians more even, the width of the branches also needs to be increased. We also analyzed the headway distance and found that almost all the volunteers in the experiment were under the free system. The results are helpful for correction of the multimerging simulation model and design improvement of the daily multimerging scene.

Behavior of KCNQ Channels in Neural Plasticity and Motor Disorders.

The broad distribution of voltage-gated potassium channels (VGKCs) in the human body makes them a critical component for the study of physiological and pathological function. Within the KCNQ family of VGKCs, these aqueous conduits serve an array of critical roles in homeostasis, especially in neural tissue. Moreover, the greater emphasis on genomic identification in the past century has led to a growth in literature on the role of the ion channels in pathological disease as well. Despite this, there is a need to consolidate the updated findings regarding both the pharmacotherapeutic and pathological roles of KCNQ channels, especially regarding neural plasticity and motor disorders which have the largest body of literature on this channel. Specifically, KCNQ channels serve a remarkable role in modulating the synaptic efficiency required to create appropriate plasticity in the brain. This role can serve as a foundation for clinical approaches to chronic pain. Additionally, KCNQ channels in motor disorders have been utilized as a direction for contemporary pharmacotherapeutic developments due to the muscarinic properties of this channel. The aim of this study is to provide a contemporary review of the behavior of these channels in neural plasticity and motor disorders. Upon review, the behavior of these channels is largely dependent on the physiological role that KCNQ modulatory factors (i.e., pharmacotherapeutic options) serve in pathological diseases.

The passive control on flow and heat transfer with streamwise micro grooves

The flow behavior of smooth channel and channel with streamwise micro grooves are numerically compared at Reynolds number 3000–6000. The numerical prediction results show that the streamwise micro grooves can effectively promote the heat transport in boundary layer. In special cases, the streamwise micro grooves can suppress the ejection and sweep motions of turbulent coherent structure to a certain extent, which is conducive to the improvement of the stability of near-wall flow structure and the reduction in wall shear stress. In addition, 2.16% of drag reduction can be obtained. Furthermore, the streamwise micro grooves increase the number of large-scale vortices and destroy the thermal boundary layer. With the help of the streamwise micro grooves, Nusselt number increases by 8.2% ~ 10.7% in the range of considered Reynolds number.

Mangrove colonization on tidal flats causes straightened tidal channels and consequent changes in the hydrodynamic gradient and siltation potential

A healthy mangrove ecosystem includes diverse landscape structures, such as tidal flats, tidal channels, and areas with circulating waters, in addition to mangrove stands. The complex structure of mangrove forests affects the hydrodynamics and sediment transport behaviour of tidal channels. Understanding the influence of the mangrove invasion of tidal flats on the pattern and stability of tidal channels is essential. In this study, two types of remote sensing images, Google Earth images and aerial photographs, were collected to analyze the relationship between mangrove colonization and changes in tidal channel patterns. After applying binary image processing, these two kinds of images show similar abilities to discriminate the locations, extents, and boundaries of mangroves and tidal channels. We found that the mangrove area was inversely proportional to the tidal channel sinuosity and width. The tidal channels exhibited a meandering pattern with a wider width before the mangroves invaded the tidal flats. After the expansion of the mangroves, the tidal channels gradually transformed into a straight shape with a narrower width. After the mangroves developed into forests, the tidal channels maintained a straight and stable pattern. Since mangroves promote siltation and increase the elevation of the surrounding mudflats, the habitat suitability for mangroves in the neighbouring tidal flat areas may vary. These processes may help expand mangrove habitats, thereby compressing the area of flats and changing the shape of tidal channels. Due to tidal current effects, the unit stream power of a straight tidal channel is approximately twice that of a meandering channel, indicating that straight tidal channels have a stronger anti-siltation capability. Our research also found that the tidal channels may return to a meandering pattern when mangroves are degraded or die and their area decreases. This study provides key evidence that mangroves affect tidal channel types and hydrodynamic characteristics, thus providing a useful reference for restoring and managing estuarine mangrove ecosystems.