Effective Channel Research Articles

Adaptive Hybrid Deep Learning Based Effective Channel Estimation in MIMO-Noma for Millimeter-Wave Systems with an Enhanced Optimization Algorithm

The channel estimation is crucial in the “millimeter Wave (mmWave) Massive Multiple-Input MultipleOutput (MIMO) and Non-Orthogonal Multiple Access (NOMA)” devices. Hybrid beamforming techniques are employed nowadays to minimize the complexity and equipment price. However, the absence of digital beam forming in mmWave affects the dynamic range and accuracy of the channel estimation. Previous research has concentrated mainly on predicting narrow-band mmWave channels using deep learning networks, as the wideband channels of mmWave create a considerable range and noise issue. Accurate channel estimation in the MIMO system is challenging because of the increased number of antennas and radio frequency (RF) chains. MIMO system communications using mmWave are frequently chosen because of their massive spectrum resources. Therefore, it is essential to tackle the obstacles obtained in the standard channel estimation framework by developing a MIMO-NOMA network with the help of deep learning methods Hence, this paper proposes an efficient hybrid deep learning model for channel estimation in MIMO-NOMA for mmWave systems. At first, the channel estimation is carried out using the Adaptive Hybrid Deep Learning (AHDL) model, where it combines both Autoencoder and Recurrent Neural Network (RNN). Here, the parameters are optimized using the Improved Red-tailed Hawk Algorithm (IRHA). Later the hardware cost and system complexity are reduced by performing the hybrid beam-forming process. Numerical results show that the proposed channel estimation and pilot estimation process outperforms the state-of-the-art approaches.

Smart city construction and quality upgrading of export products: Evidence from China

Smart cities, as an advanced form of urban development in the digital age, are likely to profoundly affect the operations of local businesses. This paper analyzes the impact of smart city construction on the quality of firms’ export products by exploiting a quasi-natural experiment based on a smart city pilot policy in China and employing the staggered difference-in-differences (DID) method. Our empirical results reveal that the implementation of the policy significantly improves the export product quality of local firms, and this finding remains quite robust after a series of sensitivity tests. Mechanism analysis shows that the improvement of innovation efficiency and the reduction of transaction costs are two effective channels through which smart city construction enhances export product quality. Heterogeneity analysis reveals that the policy effects are more prominent in high-tech industries, cities with high administrative levels, the eastern and central regions, non-state-owned firms, and general trade firms, which enjoy greater policy dividends than their counterparts.

Путешествие между каналами: формирование клиентского опыта в цифровой среде

In modern marketing, researchers are focused on the omnichannel approach due to the growing number of communication channels and sources of consumer information about brands. This paper examines the complexity and multifactorial nature of the omnichannel approach in the formation of customer experience and marketing communications in the digital environment. The article discusses the concept of a “Consumer Journey Map”, which reflects the stages of making a purchase decision, after-sales interaction and the customer experience formed within this path. This approach allows you to define and analyze the touchpoints with the consumer and information messages at each stage of the consumer journey in order to create a positive brand image. The consumer’s journey is formed by the sequential passage of a number of points of contact, which may belong to the brand, its partners or be independent. This affects the degree of brand control over the information at each of these points. Particular attention is paid to the complexity of tracking the entire variety of contact points through which the customer passes on the way to making a purchase. The management of this variety of points from the standpoint of a single communication environment of brand and consumer interaction is the subject of omnichannel marketing research. Within the framework of this study, the author considers the evaluation of the effectiveness of marketing channels at the stage of preparation for purchase. These channels may be underestimated, since in terms of direct return on marketing investments, they lose to the final pre-purchase channels, but they play a key role in shaping the customer experience leading to subsequent purchases. The article presents the results of a study of online communication based on a company providing educational services. This study demonstrates the relationship between the volume of investments in paid promotion channels and the total revenue from online channels. The results of the study emphasize the importance of the omnichannel approach in modern communication, where the buyer interacts with the brand in various channels and perceives communication as a single continuous process, even when switching from one channel to another.

Real-FlexE: Real-time Flexible channel Emulator

In digital communications, accurately modeling and replicating the channel effects between a transmitter and receiver is essential to assess their impact on transmitted data. Access to a real-time channel emulator is therefore crucial in the development of telecommunication systems. This paper presents a configurable, flexible, and high-performance FPGA-based channel emulator that supports multiple channel models, including Doppler, AWGN, and multi-path Fading. We explore bit-width precision in the components and present trade-offs between quality and resource utilization. Our exploration demonstrates ∼25%–∼45% savings in various resources while maintaining the accuracy of the channel effects and operating at a high throughput of 500 Msps.

Assembly of artificial photo-enzyme coupling nanoreactor for boosting photodegradation of trace bisphenol A pollutant in water

It is a difficult issue to remove the trace persistent organic phenolic pollutants in water. Herein, a new artificial horseradish peroxidase (HRP)/hierarchical carbon nitride (HCN) photo-enzyme coupling nanoreactor is assembled by immobilizing HRP on HCN, which achieves the high-efficiency degradation performance for trace bisphenol A (BPA) in water. Besides the promoted charge separation efficiency as well as visible light harvest capacity, the hollow and abundant pores structure of HCN/HRP can provide a confinement effect and molecular diffusion channels to promote photo-enzyme synergic catalytic effect, thus boosting degradation reaction of BPA. Compared with original HCN, the optimal HCN/HRP-3 sample obtain a higher degradation rate of 0.0575 min−1, which is 3.60 and 125 times as large as that over original HCN (0.016 min−1) and HRP (0.00046 min−1), respectively. Meanwhile, the mineralization ability of the HCN/HRP photo-enzyme coupling nanoreactor is enhanced dramatically owing to the far higher TOC removal efficiency of BPA with 81.05 % within 60 min than original HCN (37.63 %). The photocatalytic reaction mechanism investigations demonstrate that h+, •O2− and •OH all take part in the degradation process of BPA and the importance order of h+ > •O2− > •OH. This work provides an innovative design philosophy for the assembly of photo-enzyme synergic catalytic system to effectively remove the organic pollutants in water.

A multi-level study on principals’ Guanxi-driven impact on teachers’ work and home life: insights from Malaysia

Purpose Guided by the conservation of resources theory, this study aims to present a comprehensive framework examining leadership, Guanxi, work-family conflict and work engagement. It specifically explores how group-level transformational leadership influences individual-level Guanxi and work-family conflict and how these factors, in turn, impact work engagement. Design/methodology/approach The study surveyed 473 teachers in the Klang Valley, Malaysia, and used hierarchical linear modelling. Findings The results reveal that transformational leadership directly enhances non-work relationships, reduces work-family conflict and indirectly predicts increased work engagement. This indirect influence occurs through the mediation of Guanxi and the work-family conflict. Notably, while stronger Guanxi is associated with greater work engagement in the professional sphere, it does not necessarily mitigate the work-family conflict in the personal domain. Originality/value These findings provide valuable insights into maintaining and enhancing work engagement by implementing transformational leadership through more effective channels, such as Guanxi and work-family conflict management.

Corporate social responsibility on social media: a scoping review of the literature

Purpose The purpose of this study is to generate a better understanding of the nature of Corporate Social Responsibility (CSR) communication on social media. In fact social media are one of the most effective communication channels in contemporary business settings. Due to their inner characteristics, they should be the ideal channel for communicating CSR topics. Over the last 15 years, a variety of researches discussed the interplay between CSR and social media, resulting in a rather tangled body of knowledge. Design/methodology/approach This study proposes a scoping review of published academic literature at the intersection of these two research bodies (i.e. CSR and social media communication) to shed light on the nature of the communication, strategic challenges and practices, as well as their key factors and impact. Findings To date, academic research related to the nature of CSR on social media is fragmented and blurry. This research sheds light on the challenges of interactive social media communication in CSR and presents an account of key strategies, tactics and possible impacts for these challenging communication practices. Originality/value This research generates a better understanding of the nature of CSR communication on social media, strategic challenges and practices, as well as their key factors and impact. It is the tentative of generating a synthetic account of relevant literature in the field.

Non-metallic plasmonic effect and step-like charge transport channel synergistically accelerate surface reaction kinetics and charge separation of TiN/CdS-sensitized ZnO photoanode for efficient photoelectrochemical hydrogen evolution

This work demonstrates the first application to employ TiN/CdS to sensitize ZnO nanotube arrays (NTAs) photoanode for drastically enhanced solar-driven hydrogen evolution through a photoelectrochemical (PEC) cell. The CdS/TiN-sensitized ZnO NTAs photoanode shows drastically boosted PEC water splitting capability for producing hydrogen with a production rate of 168 μmol cm−2 h−1, 1.5- and 18.4-folds that of CdS-sensitized and unsensitized ZnO NTAs photoanodes, respectively. UV–vis absorption spectra demonstrate a significant enhancement in light harvesting efficiency of ZnO with the incorporation of CdS and TiN nanoparticles (NPs). Electrochemical measurement results indicate that TiN NPs accelerates the water oxidation surface reaction kinetics of the photoanode and provides abundant electrochemical active sites. Photoluminescence spectra indicate efficient charge carrier separation in CdS/TiN-sensitized ZnO NTAs and the role as the hot electron provider of TiN NPs. This study provides a new nonmetal plasmonic photoelectrode for efficiently converting solar energy into the clean energy and chemical fuels.

Numerical research on structure and performance optimization of a pioneering water-cooled fully premixed gas-fired equipment

To meet ultra-low emissions, traditional diffused low-nitrogen gas combustion technologies are not effective or extremely laborious in controlling the emissions of NOx. Thus, this study innovatively proposes a water-cooled fully premixed gas combustion technology and explores its impact on pollutant emissions through numerical simulation. The effects of the burner inlet channel’s equivalent diameter (de), the relative positioning of two rows of buried tubes, and the burner type on combustion in the boiler are explored in-depth. As de decreases, a progressive reduction in NOx emissions is observed and an anti-backfiring effect is enhanced. Moreover, using a concave burner and placing buried tubes in the combustion chamber efficiently reduces the combustion temperature and thus NOx emissions. Finally, a ternary phase diagram is constructed to guide structural design optimization and clearly depicts the effect of Airflow channel width (SW), Dimensionless distance between the first row of buried tubes and the burner nozzle (D1), and Dimensionless longitudinal distance of buried tubes (D2) on NOx and CO emissions. Under the optimized structural condition, the water-cooled fully premixed gas combustion reveals great potential to synergistically control NOx emissions to as low as 11 mg/m3 and CO concentration to 10−6 mg/m3. This research provides valuable reference data for theoretical research and equipment design.

Unsteady Aerodynamic Forces of Tandem Flapping Wings with Different Forewing Kinematics.

Dragonflies can independently control the movement of their forewing and hindwing to achieve the desired flight. In comparison with previous studies that mostly considered the same kinematics of the fore- and hindwings, this paper focuses on the aerodynamic interference of three-dimensional tandem flapping wings when the forewing kinematics is different from that of the hindwing. The effects of flapping amplitude (Φ1), flapping mean angle (ϕ1¯), and pitch rotation duration (Δtr1) of the forewing, together with wing spacing (L) are examined numerically. The results show that Φ1 and ϕ1¯ have a significant effect on the aerodynamic forces of the individual and tandem systems, but Δtr1 has little effect. At a small L, a smaller Φ1, or larger ϕ1¯ of the forewing can increase the overall aerodynamic force, but at a large L, smaller Φ1 or larger ϕ1¯ can actually decrease the force. The flow field analysis shows that Φ1 and ϕ1¯ primarily alter the extent of the impact of the previously revealed narrow channel effect, downwash effect, and wake capture effect, thereby affecting force generation. These findings may provide a direction for designing the performance of tandem flapping wing micro-air vehicles by controlling forewing kinematics.

Characterization of the structural features of Ti-6Al-4V hollow-strut lattices fabricated by laser powder bed fusion

Hollow-strut metal lattices are novel cellular materials. Compared to their solid-strut counterparts, their powder bed fusion additive manufacturing (PBF-AM) features remain largely uninvestigated. This work focuses on characterizing the hollow-strut internal channel and nodal profiles, the defects and microstructures of the hollow-strut thin walls, and the inner surface conditions of the LPBF-manufactured body-centred cubic (BCC) Ti-6Al-4V hollow-strut lattices with different relative densities. BCC lattices are selected because of the low inclination angle (35.26°) of their constituent struts. These low-inclination hollow struts are designed using a recent model developed for PBF of inclined solid struts, together with considerations to prevent powder occlusion and ensure easy removal of powder particles. Detailed characterization indicates that our design considerations resulted in high-quality hollow-strut BCC Ti-6Al-4V lattices, which provide useful design insights for PBF-AM of hollow-strut metal lattices. In terms of microstructure, the Ti-6Al-4V hollow-strut thin walls (≤ 0.5 mm thick) exhibited different microstructures compared with Ti-6Al-4V solid struts, due to the heat accumulation effect in the inner channels. The implications are discussed for in-situ microstructure control.

Boosting photocatalytic efficiency and nonlinear optical response of graphitic carbon nitride by infusing carbon nanotubes

Nanostructured materials are widely studied for their light-driven physical and chemical processes, which are key to their potential in photophysical applications. We introduce a one-pot solid-state pyrolysis technique for the synthesis of graphitic carbon nitride/carbon nanotube (g-C3N4/CNT) composites. The formation of the composite was characterized through X-ray diffraction, scanning and transmission electron microscopy, and X-ray photoelectron spectroscopy. Notably, UV-vis diffuse reflectance spectroscopy indicated a reduction in the bandgap of pure g-C3N4 from 2.6 eV to 2.35 eV with the incorporation of 0.5 wt% CNT. The nonlinear optical transmission of the samples was analyzed at 532 nm using the open-aperture Z-scan technique employing 5 ns laser pulses, revealing a twelve-fold increase in the two-photon absorption coefficient (b) for g-C3N4/CNT0.5 compared to pristine g-C3N4. Remarkably, g-C3N4/CNT0.5 showed enhanced photocatalytic efficiency in degrading bisphenol A (BPA), with the kinetic constant (k) being ten times higher than that of pure g-C3N4. The improved photocatalytic performance of g-C3N4/CNT0.5 is attributed to the presence of CNTs, which act as effective electron acceptors and transfer channels, significantly enhancing the separation of photogenerated charge carriers in g-C3N4, as evidenced by the decreased intensity in the photoluminescence spectrum.

Contextual Factors Influencing Online Support Providers’ Motivations and Message Provision

This study examined how contextual factors influence support providers’ motivations and message provision. Participants (N = 602) provided supportive messages in response to support-seeking posts sent either publicly or privately through either Facebook or an online support group. Findings revealed that providers’ motivations and message provision varied as a function of the channel and privacy of communication. Moderated mediation analyses showed that privacy moderated the indirect effect of channel on verbal person-centered message provision through approach motivation. This project advances extant understanding regarding direct and indirect effects of contextual factors and motivations on the quality of supportive messages people produce.

Government spending efficiency, fiscal decentralization and regional innovation capability: Evidence from China

Improving regional innovation is the key to achieving high-quality development, and regional innovation requires government support. However, a notable research gap exists in studies examining the relationship between government spending efficiency and regional innovation. Based on the panel data of 30 provinces in China from 2000 to 2021, this study verifies the positive impact of government spending efficiency on regional innovation capacity and its mechanism. Notably, the Consumer Price Index has been selected as an instrumental variable through a rigorous theoretical analysis to address the potential endogeneity and ensure the robustness of the findings. The findings also suggest that government spending efficiency can do better in promoting regional innovation capability in higher-investment preference areas, less financial development level regions. Further analysis reveals that human capital and advanced industrial structure play a great channel effect, while fiscal decentralization positively moderates the relationship between government spending efficiency and regional innovation capability. This study deepens our understanding of the impact of fiscal policy on local innovation development from different perspectives. Furthermore, it provides a reference to developing countries on the importance of local government in optimizing regional innovation.

In-Depth Research on the Behavioral Impact of Violence-Oriented Cartoons among Children

One significant experience in children's early life is watching cartoons. This activity has a significant impact on a variety of variables, including kids' behavioral and cognitive development. This study focuses on school-age children, namely those in the 4–13 age range. This study focuses on the effects of the Violence-Oriented Cartoons channel on children's entire development, including language, motor, social learning, social cognitive, and moral development. 500 samples from various ages of children’s Group A and Group B were gathered for this investigation. This study aims to investigate the behavioral and emotional effects of exposure to violence-oriented cartoons on children. In particular, it aims to evaluate the effects of this type of social behavior, aggressiveness levels, attention span, emotional reactions, and the desensitization of violence in comparison to nonviolent cartoons. Using a sample of 500 children, 200 were exposed to non-violence-oriented cartoons and 300 were exposed to violence-oriented cartoons. The study used two groups. The study highlights that children who watched violent cartoons showed significantly higher levels of aggression, lower social behavior, shorter attention spans, increased desensitization, and stronger negative emotional responses than children who watched nonviolent cartoons. Study finds the importance of careful consideration of children's media content and suggests the potential benefits of limiting exposure to violent imagery in cartoons.

Collective intentions of the social economy: An experiment on the community currency of the French Basque country

Community currencies (CCs) are common social economy instruments for aligning market transactions with social commitments. They change incentives, encouraging trade within the CC network, but may also symbolize and thereby amplify users’ commitment to social values of solidarity and cooperation. The behavioral effect of the second channel, moreover, is clouded by endogenous use of the CC: commitment encourages use, but does use also trigger commitment? We disentangle the direction of causality with a lab-in-the-field ultimatum game experiment, which confronts participants with a choice between more or less competitive responses. By exogenously varying the currency in which the game is played (CC or euros), we isolate the causal effect of the CC on behavior. Self-declared regular users of the currency are less competitive when playing in the CC than when playing in euros. This is not due to unobserved differences in the individuals, because when playing in euros, their behavior is the same as non-users’. Nor is it due to non-convertibility of the CC, as non-users’ behavior is not affected by the currency. We therefore isolate the CC as a “trigger of cooperativeness” for those who have a base-level of commitment to it.

The effect of temperature on the electrical characteristics of zigzag and armchair black phosphorus based 2D MOSFET

Abstract A first time comparative study of the thermal dependence of vital electrical characteristics of 2D MOSFETs based on black phosphorus for both zigzag and armchair orientations is presented in this paper. It is seen that a higher in-plane thermal conductivity in zigzag direction results in a much better on state current performance which comes at the cost of orders of magnitude increase in gate leakage and a reduced on to off state current ratio. The effect of temperature on threshold voltage (VTH), short channel effects like drain induced barrier lowering (DIBL), subthreshold swing (SS), Schottky barrier height ΦSB and transconductance behavior in both zigzag and armchair orientations is thoroughly discussed and the inherent physical mechanisms resulting the variations are also presented. Though increase in temperature is found to deteriorate the SS and drain conductance but at the same time, it is found to improve the short channel performance of the devices under consideration.

Hydrotalcite-Enhanced Tough and Strong Hydrogel Endowed by Coordination and Electrostatic Interactions for Both Strain and Pressure Sensors.

Polymer hydrogels have a wide range of applications in the field of flexible wearable devices from the perspective of easy commercialization and environmental compatibility. However, traditional hydrogels often fail to achieve adequate mechanical strength and performance such as toughness, resilience, and ionic conductivity. Herein, a significant enhancement of tensile strength in 2 orders of magnitude (from 36 kPa to 1.5 MPa) is obtained by the introduction of hydrotalcite into polymer network via multiple, multilevel, and strong interactions of strengthened interface interactions, and the enhancement effect is superior to most of known records. Meanwhile, the enhanced conductivity may be rationally attributed to effective channels of hydrotalcite for ion transport. As a result, high toughness (9.5 MJ/m3), stretchability (1520%), excellent resilience (100% rebound of 400% strain), high conductivity (2.6 mS/cm), and low-temperature resistance are successfully achieved. The work shows an efficient approach to design desired ultratough and multifunctional hydrogels.

Study on the Dispersion Characteristics of Coal Complex Resistivity under the Effect of Liquid Nitrogen Cyclic Freeze-Thaw and Evaluation of Permeability Enhancement.

The effect of liquid nitrogen freeze-thaw fracturing on coal seams can be potentially evaluated by the complex resistivity method. The real part (Reρ) and the imaginary part (Imρ) of the complex resistivity and permeability of coal were determined under different cycle times and in different bedding directions. The reason for permeability enhancement was discussed, and the dispersion mechanism of complex resistivity during cyclic freeze-thaw fracturing was analyzed. The results indicated that (1) the complex resistivity parameters have a good response to the cycle times; Reρ, |Imρ|, and the dispersion degree (α) are positively correlated with cycle time; the fully polarized frequency (f p) of Reρ, the characteristic frequency (f c) of Imρ, and variation are negatively correlated with cycle time. (2) The difference in complex resistivity parameters between the vertical bedding direction and the parallel bedding direction is significant, and the difference in electrical properties of the bedding structure continuously decreases with the increase in cycle time. (3) Under the effect of liquid nitrogen cyclic freeze-thaw, a complex network of fractures in coal is formed, the anisotropic characteristics of coal are weakened, and effective conductive channels are damaged. The peak frost heave force decreases exponentially with the increase in cycle time, and the difference in bedding electrical properties gradually disappears. (4) Comparing the inversion degree of measured data with three conductive models, ρ0 and τ are selected as the optimum parameters for evaluating the effect of liquid nitrogen cyclic freeze-thaw. A logarithmic permeability evaluation model is constructed based on ρ0 and τ. This work provides a new perspective based on electrical detection for evaluating the permeability enhancement of coal during liquid nitrogen cyclic freeze-thaw.

Barriers of access to primary healthcare services by National Health Insurance Fund capitated members in Uasin Gishu county, Kenya

PurposeThe study identifies provision of primary healthcare services using the capitated health model as a prerequisite for promoting positive healthcare outcomes for a country’s population. However, capitated members have continued to face challenges in accessing primary healthcare services despite enrolment in the National Health Insurance Fund (NHIF). This study sought to determine if variables such as patient knowledge of the NHIF benefit package, NHIF Premium Payment processes, selecting NHIF capitated health facilities, and NHIF Communication to citizens’ influences access to primary healthcare services.MethodA cross-sectional analytical research design was adopted. Data was collected from patients who were using NHIF cards, who were drawn from health facilities. Data was collected using a structured questionnaire where some of the questions were rated using the Likert scale to enable the generation of descriptive statistics. Data was analysed using descriptive and inferential statistics. Logistic regression was conducted to determine the relationship between the independent and the dependent variables.ResultsThe study found that four independent variables (Patient knowledge of NHIF Benefit Package, NHIF Premium Payment processes, Selecting NHIF capitated Health Facility, and NHIF Communication to citizens) were significant predictors of access to capitated healthcare services with significance values of .001, .001, .001 and .001 respectively at 95% significance level.ConclusionsThe study found that familiarity with the NHIF benefit package significantly influenced NHIF capitated members' access to primary healthcare services in Uasin Gishu County. While most members were aware of their healthcare entitlements, there's a need for increased awareness regarding access to surgical services and dependents' inclusion. Facility selection also played a crucial role, influenced by factors like freedom of choice, NHIF facility selection rules, facility appearance, and proximity to members' homes. NHIF communication positively impacted access, with effective communication channels aiding service accessibility. Premium payment processes also significantly linked with service access, influenced by factors such as payment procedures, premium awareness, payment schedules, registration waiting periods, and penalties for defaults. Overall, patient knowledge, NHIF communication, premium payment processes, and facility selection all contributed positively to NHIF capitated members' access to primary healthcare services in Uasin Gishu County.