Fresh Multiple Access: A Unified Framework Based on Large Models and Mean-Field Approximations

Information freshness has attracted increasingly attention in the past decade as it plays a critical role in the emerging real-time applications. Age of information (AoI) holds the promise of effectively characterizing the information freshness, hence widely considered as a fundamental performance metric. However, in multiple-device scenarios, most existing works focus on the analysis and optimization of AoI based on queueing systems. The study for a unified approach for general multiple access control scheme in freshness-oriented scenarios remains open. In this paper, we take into consideration the combination of the fundamental freshness metric AoI and multiple access control schemes to achieve efficient cross-layer analysis and optimization in freshness-oriented scenarios, which is referred to as fresh multiple access. To this end, we build a unified framework with a discrete-time tandem queue model for fresh multiple access. The unified framework enables the analysis and optimization for general multiple access protocols in fresh multiple access. To handle the high dimension framework embedded in fresh multiple access, we introduce large model approaches for the Markov chain formulation in AoI oriented scenarios. Two typical AoI-based metric are studied including age of incorrect information (AoII) and peak AoII. Moreover, to address the computational complexity of the large model, we present mean-field approximations which significantly reduces the dimension of the Markov chain model by approximating the integral affect of massive devices in fresh multiple access.Comment: accepted by Journal of Communications and Network

Effect of Temperature on the Corrosion Behaviours of L360QCS in the Environments Containing Elemental Sulphur and H₂S/CO₂

The effect of temperature on the corrosion behaviours of L360QCS in H₂S, CO₂ and elemental sulphur environments are investigated. The corrosion weight-loss rate, microscopy, chemical compositions and phase compositions of corrosion products are studied by means of the weight-loss analysis, SEM and XRD techniques. As shown, the corrosion rate increased greatly with an increase of the temperature, and the corrosion scale is dropped off easily because of the weak adhesion force between the matrix and the corrosion products. The composition and structure analysed by energy-dispersive x-ray spectroscopy (EDS) and XRD show that the corrosion product scales are composed of cubic FeS and little tetragonal FeS.Исследовано влияние температуры на режимы коррозии L360QCS в атмосферах H₂S, CO₂ и атомарной серы. Скорость коррозии, измеряемая по потере веса, микроскопия, химический и фазовый состав продуктов коррозии определялись анализом потери веса, СЭМ и рентгеноструктурным анализом (РСА). Показано, что скорость коррозии сильно возрастает с температурой, и коррозионная окалина легко отпадает благодаря слабой силе адгезии между матрицей и продуктами коррозии. Исследования состава и структуры методами рентгеноспектрального электронно-зондового микроанализа и РСА показали, что окалины продуктов реакции состоят из кубического FeS и небольшой части тетрагонального FeS.Досліджено вплив температури на режими корозії L360QCS в атмосфері H₂S, CO₂ та атомарної сірки. Швидкість корозії, яка вимірюється за втратами ваги, мікроскопія, хемічний та фазовий склад продуктів корозії визначалися аналізою втрати ваги, СЕМ та рентґеноструктурною аналізою (РСА). Показано, що швидкість корозії сильно збільшується з температурою, і корозійна жужелиця легко відпадає через слабку силу адгезії між матрицею та продуктами корозії. Дослідження складу та структури методами рентґеноспектральної електронно-зондової мікроаналізи та РСА показали, що жужелиці продуктів реакції складаються з кубічного FeS та незначної частки тетрагонального FeS

Simulation of ultrasonic vibration in a liquid aluminum bath for sapphire surface modification

Ultrasonic vibration has been found to play a significant role in promoting surface nano-crystallization of sapphire in a liquid aluminum bath. And the distribution of the vibration field is critical in controlling the modification procedure. Here, distribution of the ultrasonic vibration in a liquid aluminum bath was investigated by finite element method (FEM). Effects of shape of the ultrasonic horn and distance between the horn and the sapphire plates were investigated. It was found that the ultrasonic vibration density is high in the area adjacent to the ultrasonic horn. The distance between the horn and the plates significantly influence the vibration distribution. And the vibration density decreased significantly at the liquid/solid interface, indicating obvious energy absorption there. Vibration energy grads can be formed on sapphire surface. And this phenomenon shall be used to achieve different aims

Polarization State Manipulation of Electromagnetic Waves with Metamaterials and Its Applications in Nanophotonics

Polarization state is an important characteristic of electromagnetic waves. The arbitrary control of the polarization state of such wave has attracted great interest in the scientific community because of the wide range of modern optical applications that such control can afford. Recent advances in metamaterials provide an alternative method of realizing arbitrary manipulation of polarization state of electromagnetic waves in nanoscale via ultrathin, miniaturized, and easily integrable designs. In this chapter, we give a review of recent developments on polarization state manipulation of electromagnetic waves in metamaterials and discuss their applications in nanophotonics, such as polarization converter, wavefront controller, information coding, and so on

Prospects for Bioethanol Production from Macroalgae

Macroalgae (mainly marine macroalgae, i.e. seaweeds) are considered as a very promising source for bioethanol production, because they have high carbohydrate contents, superior productivity, and wide adaptability. Macroalgae are generally grouped into three major categories: red, green, and brown algae. Each category has thousands of species, and each species possesses its unique cellular structure, biochemistry, and constitutes. Converting macroalgae to bioethanol involves pretreatment, saccharification, fermentation, and distillation; and the establishment of economic pretreatment methods is always the first key step for bioethanol production. In present, dilute-acid or alkali hydrolysis is typically used to treat macroalgal biomass. Macroalgae can be depolymerized under mild conditions as they have low lignin content. The resulting polysaccharides can be converted to ethanol through enzymatic hydrolysis, followed by adding bacteria, such as Saccharomyces cerevisiae and recombinant Escherichia coli KO11. Compared with the separate hydrolysis and fermentation process, the simultaneous saccharification and fermentation process often provided higher ethanol titer and conversion efficiency. However, the research on bioethanol production from macroalgae is still in its early stage due to both technical and economic barriers, significant amount of research and development work is needed prior to the commercialization of bioethanol manufacture from macroalgae.Citation: Chen, J., Bai, J., Li, H., Chang, C., and Fang, S. (2015). Prospects for Bioethanol Production from Macroalgae. Trends in Renewable Energy, 1(3), 185-197. DOI: 10.17737/tre.2015.1.3.001

3D Molecular Generation via Virtual Dynamics

Structure-based drug design, i.e., finding molecules with high affinities to the target protein pocket, is one of the most critical tasks in drug discovery. Traditional solutions, like virtual screening, require exhaustively searching on a large molecular database, which are inefficient and cannot return novel molecules beyond the database. The pocket-based 3D molecular generation model, i.e., directly generating a molecule with a 3D structure and binding position in the pocket, is a new promising way to address this issue. Herein, we propose VD-Gen, a novel pocket-based 3D molecular generation pipeline. VD-Gen consists of several carefully designed stages to generate fine-grained 3D molecules with binding positions in the pocket cavity end-to-end. Rather than directly generating or sampling atoms with 3D positions in the pocket like in early attempts, in VD-Gen, we first randomly initialize many virtual particles in the pocket; then iteratively move these virtual particles, making the distribution of virtual particles approximate the distribution of molecular atoms. After virtual particles are stabilized in 3D space, we extract a 3D molecule from them. Finally, we further refine atoms in the extracted molecule by iterative movement again, to get a high-quality 3D molecule, and predict a confidence score for it. Extensive experiment results on pocket-based molecular generation demonstrate that VD-Gen can generate novel 3D molecules to fill the target pocket cavity with high binding affinities, significantly outperforming previous baselines