基于涡轮蜗杆效率的研究及控制系统仿真

设计了一套基于涡轮蜗杆的性能试验台,通过一系列实验准确测量出涡轮蜗杆的传动效率。并在此基础上建立控制系统数学模型,对控制系统进行仿真。     

网络能耗最小化的射频能量源布置与发射功率设置

射频能量捕获是应对无线网络节点能量受限的有效方法之一.射频能量源（energy source,简称ES）的布置位置和发送功率决定了各个节点的能量捕获功率.现有的研究工作大部分考虑的是没有给定侯选位置的场景.然而,在实际应用场景中,网络区域往往存在很多不可布置能量源的区域,使得能量源只能在一些合理的候选位置中布置.目前仅有少量相关工作研究如何在ES的候选布置位置中选择合适布置位置.已知节点位置、节点的能量捕获功率需求值、ES的个数以及ES的候选布置位置.研究并设计了最小化ES总供能的ES布置与发送功率设置方案.首先将该问题建模为混合整数规划问题;然后分别提出了一种具有较低复杂度的启发式算法和一种能够达到更小总供能的基于遗传算法的算法.仿真结果表明,与布置位置随机挑选法相比,这两种算法的网络总功耗降低了约90%,而遗传算法可达到比启发式算法高约35%的节能效果.因此,基于遗传算法的布置算法可用于中小规模的ES布置场景,而启发式算法可用于大规模的ES布置场景.     

Near-infrared carbon nanodots for effective identification and inactivation of Gram-positive bacteria

An unacceptable increase in antibacterial resistance has arisen due to the abuse of multiple classes of broad-spectrum antibiotics.Therefore,it is significant t...     

高花青素茶呈色与花青素积累机制研究进展

茶叶(camellia sinensis)是世界上最受欢迎的无酒精的饮料,也是最古老的饮料。中国作为茶叶的发源地,拥有丰富的茶叶资源。高花青素紫芽茶作为一种特殊的茶叶变种,其中的花青素不仅有利于提高茶树自身的抵抗逆境的能力,还有显著的抗氧化、抗肿瘤、消炎及预防心脑血管疾病等保健功效,越来越受到人们的关注。近年来,对于高花青素紫芽茶树的研究主要集中在育种和茶叶适制性,以及花青素的生物合成机制。本文综述了近年来高花青素茶树的育种工作、紫芽茶中的花青素成分、高花青素茶的叶片呈色机制以及花青素合成与积累的生物学机制,并对今后的发展方向提出展望,以期更加全面的理解花青素的合成、转运和降解机制,构建健全的高花青素茶种质体系,为进一步利用提供理论依据,也为其他植物花青素的研究提供参考。     

Numerical Study of Single Bubble Growth on and Departure from a Horizontal Superheated Wall by Three-dimensional Lattice Boltzmann Method

A three-dimensional hybrid lattice Boltzmann method was used to simulate the progress of a single bubble’s growth and departure from a horizontal superheated wall. The evolutionary process of the bubble shapes and also the temperature fields during pool nucleate boiling were obtained and the influence of the gravitational acceleration on the bubble departure diameter (BDD), the bubble release frequency (BRF) and the heat flux on the superheated wall was analyzed. The simulation results obtained by the present three-dimensional numerical studies demonstrate that the BDD is proportional to \(g^{\mathrm {-0.301}}\), the BRF is proportional to \(g^{\mathrm {-0.58}}\), and the averaged wall heat flux is proportional to \(g^{\mathrm {0.201}}\), where g is the gravitational acceleration. These results are in good agreement with the common-used experimental correlations, indicating the rationality of the present numerical model and results.     

Battery voltage transfer method for multi-cells Li-ion battery pack protection chips

Analog Integrated Circuits and Signal Processing - In order to suppress leakage current caused in the traditional multi-cells series Li-ion battery pack protection system, a new battery voltage...     

J-Type Self-Assembled Supramolecular Polymers for High-Performance and Fast-Response n-Type Organic Electrochemical Transistors

To date, high-performance organic electrochemical transistors (OECTs) are almost all based on conjugated polymers. Small molecules can be synthesized with high purity without batch-to-batch variations. However, small molecules require highly crystalline films and good molecular packings to achieve high charge carrier mobilities. Such features make their films unsuitable for ion diffusion or make their molecular packing distorted due to ion diffusion, resulting in poor ion/charge carrier transport properties and slow response speed. Herein, it is proposed to construct small-molecule-based supramolecular polymers to address these issues. A molecule, namely TDPP-RD-G7 is designed, which exhibits J-type self-assembling behaviors and can form supramolecular polymers in solution and conjugated-polymer-like networks in solid state. More importantly, the porous supramolecular polymer networks allow fast ion diffusion and greatly increase the device response speeds. As a result, the TDPP-RD-G7 exhibits record fast response speeds (τ_on/τ_off) of 10.5/0.32 ms with high figure-of-merit (µC*) of 5.88 F cm⁻¹ V⁻¹ s⁻¹ in small-molecule OECTs. This work reveals the possible reasons that hinder the response speeds in small-molecule OECTs and demonstrates a new “supramolecular polymer” approach to high-performance and fast-response small-molecule-based OECTs.     

Microstructural Features and Mechanical Behaviors of Al0.5Cr0.8CoFeNi2.5V0.2 High-Entropy Alloys Fabricated by Selective Laser Melting Technique

In this work, high strength and ductile Al_0.5Cr_0.8CoFeNi_2.5V_0.2 high-entropy alloys (HEAs) were fabricated by the selective laser melting (SLM) technique. After orthogonal experiments, it was verified that a wide SLM processing parameter window can be used to produce crack-free samples for the investigated HEAs. All the printed HEA samples exhibit good densification higher than 98.3%. It was found that obvious epitaxial growth leads to the formation of the cylindrical and equiaxed ordered face-centered cubic (FCC) crystals, displaying the characteristics of sub-cylindrical and sub-cellular microstructures. The low-angle grain boundaries (LAGBs) prefer appearing around subgrain structures, while the high-angle grain boundaries (HAGBs) tend to form around coarse grains. Two HEA samples with high and low apparent densities were selected to observe their mechanical properties, which exhibit Vickers hardness higher than 263 HV and do not fail during compression. With increasing densification, the strength gradually rises. According to the engineering stress-strain curves during compression, the yield strength is higher than 530 MPa, while the strength near 40% engineering strain is larger than 1840 MPa. During deformation, a large density of dislocations becomes popular within subgrain structures together with the pre-existing dislocations from rapid solidification, leading to the formation of planar and cross slip bands. Within coarse cylindrical crystals, some deformation twins are also induced together with the appearance of a distinct copper-type texture during deformation. As a result, the as-printed samples display better mechanical properties than the as-cast counterpart. The present studies provide a very good HEA candidate for the SLM process, but more work should be conducted to achieve excellent comprehensive properties.     

Video multimodal emotion recognition based on Bi-GRU and attention fusion

A video multimodal emotion recognition method based on Bi-GRU and attention fusion is proposed in this paper. Bidirectional gated recurrent unit (Bi-GRU) is applied to improve the accuracy of emotion recognition in time contexts. A new network initialization method is proposed and applied to the network model, which can further improve the video emotion recognition accuracy of the time-contextual learning. To overcome the weight consistency of each modality in multimodal fusion, a video multimodal emotion recognition method based on attention fusion network is proposed. The attention fusion network can calculate the attention distribution of each modality at each moment in real-time so that the network model can learn multimodal contextual information in real-time. The experimental results show that the proposed method can improve the accuracy of emotion recognition in three single modalities of textual, visual, and audio, meanwhile improve the accuracy of video multimodal emotion recognition. The proposed method outperforms the existing state-of-the-art methods for multimodal emotion recognition in sentiment classification and sentiment regression.

     

射频供能传感网面向融合检测的部署调度方法

当射频供能传感网应用于目标检测时,对节点的部署位置和充电/感知调度表进行合理规划可有效提高系统检测质量.基于融合检测模型,首先归纳了使得系统检测质量最大化的节点部署和调度联合优化问题,证明了该问题是NP完全问题.然后分析了融合半径对检测率的影响,提出了基于贪婪算法的节点部署调度联合优化算法.通过小规模网络、大规模网络及基于真实数据集的仿真,将该算法分别与全局最优解、分阶段优化贪婪算法进行了性能比较.实现结果表明：所提出的联合优化贪婪算法获得的系统检测质量在各组仿真中均优于分阶段贪婪算法,并且在小规模网络中接近于全局最优解.