一种低开销的无线传感器网络时间同步算法

低开销是无线传感器网络时间同步算法的重要技术要求之一.为了降低同步过程中的通信开销,提出了一种基于部分广播的低开销无线传感器网络时间同步算法.算法基于TPSN算法的分层思想,利用节点的距离信息,选撵当层节点的部分相邻节点进行下一层的等级广播,从而有效地降低同步过程中的通信开销.分析了在不同的网络节点密度下广播信息包数与等级广播距离的关系,得到了不同网络节点密度下的最优等级广播距离.仿真结果表明,与TPSN算法相比,在相同的同步精度下,算法能显著地降低高密度无线传感器网络时间同步的开销.     

低成本中水处理技术

分布式中水处理是在产生污水的当地就地处理,就地回用,可大大减少中水回用所需建设的管网系统,利于降低中水处理的整体成本。发展低成本的分布式中水处理技术,可迅速解决制约中水回用的现存问题。采用先进的F2-R中水处理工艺,中水处理的整体成本可从现在的1.22元/m3降为0.77元/m3,使中水处理运行方在现行中水水价下,可以产生合理利润,这必将提高其积极性,也必将鼓励用水方尽量回收废水,并处理后回用。     

Protein profiling of low-density lipoprotein from obese subjects

Although obesity and high levels of low-density lipoprotein (LDL) are well-known risk factors for cardiovascular disease, the precise role(s) of different LDL constituents in obesity has not been explored. In the present study, we compared the LDL proteome of healthy control adults (body mass index<25) and obese subjects (body mass index>30). LDL was isolated by density-gradient ultracentrifugation and proteins were separated with 2-D PAGE, quantified, and identified by peptide mass fingerprinting using MALDI-TOF MS. A new LDL-associated protein was identified as transthyretin and found to be significantly more abundant in LDL from the obese subjects. In addition, LDL from the obese subjects contained relatively more α(1) -antitrypsin, apo J, apo C-II, than LDL from controls, and also more of an acidic isoform (pI/Mr; 5.2/23 100) of apo A-I. On the other hand, the relative amounts of apo A-IV and the major isoform of apo A-I (pI/Mr; 5.3/23 100) were significantly less in LDL from the obese subjects. Apo E was less and non-sialylated apo C-III more abundant in LDL from obese men than control men, while there were no such differences between LDL from obese and control women. These findings illustrate that obesity is not only associated with increased LDL-cholesterol levels but also with alterations in the LDL protein composition. The presence of transthyretin in LDL from obese subjects may reflect over-nutrition and affect the lipid metabolism in obesity.     

江汉盆地拖市油田低渗透油藏储层特征——古物理化学特征分析

通过镜质体反射率积分法计算地层平均古地温梯度,实验测定硬石膏包裹体“均一”温度,应用声发射(AE)Kessier效应确定古构造应力场,由CO_2浓度法计算古流体压力(P_1);同时,对裂缝充填物进行了热释光与中子活化分析。研究结果表明,成岩过程中,硬石膏和方解石所处的温度、压力及化学环境接近或类似于现代储层物理、化学环境;裂缝中硬石膏脉体呈分接段沉淀特征;裂缝充填物质主要来自于泥岩。     

Global attention retinex network for low light image enhancement

Most low-light image enhancement methods only adjust the brightness, contrast and noise reduction of low-light images, making it difficult to recover the lost information in darker areas of the image, and even cause color distortion and blurring. To solve the above problems, a global attention-based Retinex network (GARN) for low-light image enhancement is proposed in this paper. We propose a novel global attention module which computes multiple dimensional information in the channel attention module to help facilitate inference learning. Then the global attention module is embedded into different layers of the network to extract richer shallow texture features and deep semantic features. This means that the rich features are more conducive to learning the mapping relationship between low-light images to normal-light images, so that the detail recovery of dark regions is enhanced in low-light images. We also collected a low/normal light image dataset with multiple scenes, in which the images paired as training set can succeed to be applied to low-light image enhancement under different lighting conditions. Experimental results on publicly available datasets show that our method has better effectiveness and generality than the state-of-the-art methods in terms of evaluations metrics such as PSNR, SSIM, NIQE, Entropy.     

低速大转矩永磁同步电动机研究综述

电动机作为现代工业的重要动力来源,在目前“双碳战略”的政策背景下,探究如何改善其节能环保和稳定工作的性能是一个重要的课题。目前广泛使用的重载机械传动装置是感应电机+减速器的模式,由于感应电机本身的特性,难以实现变频控制,且在低速下运行不平稳,而减速器的存在既降低了传动的效率,又增大了整个机械装置的维护工作量。综上所述,这种重载装置不能适应节能环保的需要。而低速大转矩永磁同步电动机能够在低速时稳定运行,并且输出的转矩足够大,加上高效率、维护工作量小、尺寸设计灵活等特点,使用低速大转矩永磁同步电动机替代传统重载传动装置将是工业的一个重要发展方向。     

Low complexity inter coding scheme for Versatile Video Coding (VVC)

The latest coding standard Versatile Video Coding (VVC) developed by the Joint Video Experts Team (JVET) and Video Coding Experts Group (VCEG) was finalized in 2020. By introducing several new coding techniques, VVC improves the compression efficiency by 50% compared with H.265/HEVC. However, the coding complexity increases dramatically, which obstructs it from real-time application. To tackle this issue, a fast inter coding algorithm utilizing coding information is proposed to speed up the coding process. First, by analyzing the coding areas of the neighboring CUs, we predict the coding area of the current CU to terminate unnecessary splitting modes. Then, the temporally optimal coding mode generated during the prediction process is further utilized to shrink the candidate modes to speed up the coding process. Finally, the distribution of neighboring prediction modes are exploited to measure the motion complexity of the current CU, based on which the unnecessary prediction modes can be skipped earlier. Experimental results demonstrate that the proposed method can reduce the coding complexity by 40.08% on average with 0.07 dB BDPSNR decrease and 1.56% BDBR increase, which outperforms the state-of-the-art approach.     

On the Wetting States of Low Melting Point Metal Galinstan® on Silicon Microstructured Surfaces

The primary goal of this article is to measure the wetting characteristics of a low melting point metal to determine the efficacy of this type of material for possible use in thermal energy storage applications. Galinstan®, a commercially available alloy consisting of Gallium, Indium, and Tin is subjected to contact angle measurements on various silicon surfaces at varying temperatures. Due to the oxidation characteristics of Galinstan, all experiments are conducted in an inert nitrogen environment (<0.5 ppm oxygen) to maintain fluid‐like properties. This work finds that although contact angle changes with substrate and surface structure, temperature has no observable effect on contact angle. Contact angles range from 141° on smooth silicon to greater than 160° on silicon micropillars. Although a temperature dependence is not observed over the range of temperatures studied, having wetting properties of Galinstan on various surfaces is a step toward better understanding the capabilities of this and similar materials in energy management.

     

Adaptive thresholding algorithm: Efficient computation technique based on intelligent block detection for degraded document images

Document image binarization involves converting gray level images into binary images, which is a feature that has significantly impacted many portable devices in recent years, including PDAs and mobile camera phones. Given the limited memory space and the computational power of portable devices, reducing the computational complexity of an embedded system is of priority concern. This work presents an efficient document image binarization algorithm with low computational complexity and high performance. Integrating the advantages of global and local methods allows the proposed algorithm to divide the document image into several regions. A threshold surface is then constructed based on the diversity and the intensity of each region to derive the binary image. Experimental results demonstrate the effectiveness of the proposed method in providing a promising binarization outcome and low computational cost.     

Numerical investigations on dynamic stall of low Reynolds number flow around oscillating airfoils

This paper presents a 2D computational investigation on the dynamic stall phenomenon associated with unsteady flow around the NACA0012 airfoil at low Reynolds number (Re_c ≈ 10⁵). Two sets of oscillating patterns with different frequencies, mean oscillating angles and amplitudes are numerically simulated using Computational Fluid Dynamics (CFD), and the results obtained are validated against the corresponding published experimental data. It is concluded that the CFD prediction captures well the vortex-shedding predominated flow structure which is experimentally obtained and the results quantitatively agree well with the experimental data, except when the blade is at a very high angle of attack.