Joint multicast beamforming and relay design for maritime communication systems

With growing human maritime activities, supporting low-cost and high-speed information services for users at sea has become imperative. However, traditional means of maritime communications fail to provide high rate services due to their high cost and limited bandwidth. In this paper, considering abase station ashore and several offshore relay nodes, we propose a cooperative multicast communication scheme for maritime users relying on joint beamforming (BF) optimization and relay design. Specifically, we decompose our proposed joint optimization problem into two subproblems, which can be solved by the feasible point pursuit successive convex approximation approach. Furthermore, an alternating optimization algorithm is proposed, which imposes an exponentially increasing complexity as a function of the number of BF elements and the number of relays, when aiming for finding the globally optimal solution. In order to reduce this excessive computational complexity, a low-complexity distributed algorithm is also conceived and its closed-form solution is derived. Finally, the simulation results provided show that our proposed algorithm is beneficial in terms of increasing both the throughputas well as the energy efficiency

Exploring anomalous nanofluidic transport at the interfaces

Abstract Transport of ions and water is essential for diverse physiological activities and industrial applications. As the dimension approaches nano and even angstrom scale, ions and water exhibit anomalous behaviors that differ significantly from the bulk. One of the key reasons for these distinctive behaviors is the prominent influence of surface effects and related transport properties occurring at the interface under such (sub)nanoconfinement. Therefore, exploring nanofluidic transport at the interfaces could not only contribute to unraveling the intriguing ion and water transport behaviors but also facilitate the development of nanofluidic devices with tunable mass transport for practical applications. In this review, we focus on three crucial interfaces governing ion and water transport, namely liquid–gas interface, liquid–solid interface, and liquid–liquid interface, with emphasis on elucidating their intricate interfacial structures and critical roles for nanofluidic transport phenomena. Additionally, potential applications associated with liquid–gas, liquid–solid, and liquid–liquid interfaces are also discussed. Finally, we present a perspective on the pivotal roles of interfaces on nanofluidics, as well as challenges in this advancing field

Power-delay trade-off for heterogenous cloud enabled multi-UAV systems

Unmanned aerial vehicles (UAVs) have been widely used in a range of compelling applications. However, some of them are incompetent in tackling with computation-intensive tasks due to limited processing capability and battery life. In this paper, we combine the mobile edge computing and traditional cloud computing techniques for offloading the tasks from multi-UAV systems. Specifically, we jointly optimize the task scheduling and resource allocation in the heterogeneous cloud architecture, where we strike a power-delay trade-off of the system relying on the queue theory and Lyapunov optimization, followed by its optimal strategy analysis in each time slot. Moreover, we conceive an iterative algorithm with a closed-form solution at each iteration round in order to reduce the computational complexity. Finally, numerical results demonstrate both the feasibility and effectiveness of our proposed scheme. This paper validates that the heterogeneous cloud structure can be the beneficial for improving quality-of-service performance of multi-UAV systems.</p

Quantification of three-dimensional added turbulence intensity for the horizontal-axis wind turbine considering the wake anisotropy

The accurate evaluation of wake turbulence intensity (TI) is of great significance for the layout optimization of wind farms and research on control strategies. However, the existing engineering wake models still have many shortcomings in evaluating the TI in the wake of horizontal-axis wind turbines (HAWTs), especially in the near wake region. In response to this, this article proposed an analytical model based on the double-Gaussian ellipse function that can describe the three-dimensional added TI distribution in the entire wake region. Firstly, the anisotropy of wake expansion is taken into account in both the horizontal and vertical directions, assuming that the added TI distribution downstream of the HAWT is a double-Gaussian elliptical shape. Secondly, taking into account the self-similarity characteristics of flow TI, the maximum added TI and its position in the entire wake region are evaluated. In addition, considering the influence of the ground effect, the vertical turbulence distribution was corrected. Finally, the proposed added turbulence model was validated and relative error analysis was conducted using large eddy simulation (LES) data, wind field measurement data, and wind tunnel experimental data. The results show that the model had good prediction accuracy in the entire wake region, and its prediction performance was significantly improved compared to traditional models, especially in the near wake region, with the lowest even relative error of 3.66%. This model has significant advantages such as low computational cost, wide applicability, and high accuracy. It can reduce energy losses in wind farms, improve wind energy utilization efficiency, and has great potential for widespread application in large-scale wind farms

Variation in the Growth Traits and Wood Properties of Chinese Fir from Six Provinces of Southern China

To determine the phenotypic variation in 700 ten-year grafted Chinese fir collected from six provinces in southern China, 10 phenotypic traits were investigated: tree height, diameter at breast height, bark thickness, volume of timber, heartwood ratio, density of wood, hygroscopicity, tracheid length, tracheid diameter, and ratio of tracheid length to tracheid diameter. Abundant phenotypic variation was found among the six populations; the phenotypic variation coefficients all exceeded 10%, and the largest was for volume of timber. Significant variation (p &lt; 0.01 or 0.05) in traits was found among the populations, except for diameter at breast height, heartwood ratio, and tracheid diameter, while all traits differed significantly (p &lt; 0.01) within populations. The high value of repeatability (broad-sense heritability) suggested moderate genetic control of the traits. The 10 traits were strongly correlated within the entire population; strong positive correlations (p &lt; 0.01) were observed between growth traits, and significant negative correlations (p &lt; 0.01 or 0.05) were found between the density of wood and most other characteristics, except for heartwood ratio and ratio of tracheid length to tracheid diameter. Using diameter at breast height and density of wood as criteria, 98 relatively fast-growing genotypes with relatively high wood basic density were identified

An Overview of Adverse Outcome Pathway Links between PM_2.5 Exposure and Cardiac Developmental Toxicity

Fine particulate matter (PM2.5) is a significant risk factor for birth defects. As the first and most important organ to develop during embryogenesis, the heart’s potential susceptibility to PM2.5 has attracted growing concern. Despite several studies supporting the cardiac developmental toxicity of PM2.5, the diverse study types, models, and end points have prevented the integration of mechanisms. In this Review, we present an adverse outcome pathway framework to elucidate the association between PM2.5-induced molecular initiating events and adverse cardiac developmental outcomes. Activation of the aryl hydrocarbon receptor (AhR) and excessive generation of reactive oxygen species (ROS) were considered as molecular initiating events. The excessive production of ROS induced oxidative stress, endoplasmic reticulum stress, DNA damage, and inflammation, resulting in apoptosis. The activation of the AhR inhibited the Wnt/β-catenin pathway and then suppressed cardiomyocyte differentiation. Impaired cardiomyocyte differentiation and persistent apoptosis resulted in abnormalities in the cardiac structure and function. All of the aforementioned events have been identified as key events (KEs). The culmination of these KEs ultimately led to the adverse outcome, an increased morbidity of congenital heart defects (CHDs). This work contributes to understanding the causes of CHDs and promotes the safety evaluation of PM2.5.</sub

Global Reprogramming of Transcription in Chinese Fir (Cunninghamia lanceolata) during Progressive Drought Stress and after Rewatering

Chinese fir (Cunninghamia lanceolata), an evergreen conifer, is the most commonly grown afforestation species in southeast China due to its rapid growth and good wood qualities. To gain a better understanding of the drought-signalling pathway and the molecular metabolic reactions involved in the drought response, we performed a genome-wide transcription analysis using RNA sequence data. In this study, Chinese fir plantlets were subjected to progressively prolonged drought stress, up to 15 d, followed by rewatering under controlled environmental conditions. Based on observed morphological changes, plantlets experienced mild, moderate, or severe water stress before rehydration. Transcriptome analysis of plantlets, representing control and mild, moderate, and severe drought-stress treatments, and the rewatered plantlets, identified several thousand genes whose expression was altered in response to drought stress. Many genes whose expression was tightly coupled to the levels of drought stress were identified, suggesting involvement in Chinese fir drought adaptation responses. These genes were associated with transcription factors, signal transport, stress kinases, phytohormone signalling, and defence/stress response. The present study provides the most comprehensive transcriptome resource and the first dynamic transcriptome profiles of Chinese fir under drought stress. The drought-responsive genes identified in this study could provide further information for understanding the mechanisms of drought tolerance in Chinese fir

Variation in the Growth Traits and Wood Properties of Chinese Fir from Six Provinces of Southern China

To determine the phenotypic variation in 700 ten-year grafted Chinese fir collected from six provinces in southern China, 10 phenotypic traits were investigated: tree height, diameter at breast height, bark thickness, volume of timber, heartwood ratio, density of wood, hygroscopicity, tracheid length, tracheid diameter, and ratio of tracheid length to tracheid diameter. Abundant phenotypic variation was found among the six populations; the phenotypic variation coefficients all exceeded 10%, and the largest was for volume of timber. Significant variation (p &lt; 0.01 or 0.05) in traits was found among the populations, except for diameter at breast height, heartwood ratio, and tracheid diameter, while all traits differed significantly (p &lt; 0.01) within populations. The high value of repeatability (broad-sense heritability) suggested moderate genetic control of the traits. The 10 traits were strongly correlated within the entire population; strong positive correlations (p &lt; 0.01) were observed between growth traits, and significant negative correlations (p &lt; 0.01 or 0.05) were found between the density of wood and most other characteristics, except for heartwood ratio and ratio of tracheid length to tracheid diameter. Using diameter at breast height and density of wood as criteria, 98 relatively fast-growing genotypes with relatively high wood basic density were identified