基于XGBoost算法的垃圾短信分层分级治理体系

为有效整治垃圾短信,不断提升不良信息治理的精准性,文章基于XGBoost算法构建了一套科学的分层分级垃圾短信治理体系。通过对用户入网、消费、通信行为等特征进行建模与运算,识别出用户发送垃圾短信的风险系数,并定义了六级用户。分级名单生成后,依托于垃圾短信拦截系统的分级策略管理功能,分别设置相匹配的拦截策略。在加大对中高危用户的识别和拦截力度的同时,有效降低了高价值用户因不良信息治理导致被误拦截的风险。该治理体系应用于辽宁移动管理实际以来,垃圾短信平均投诉量降幅34.82%。误关停投诉率稳定在0.1%以内。一至三级高价值客户群关停投诉量降幅27.43%。     

Low-light image enhancement via deep Retinex decomposition and bilateral learning

Low-light images enhancement is a challenging task because enhancing image brightness and reducing image degradation should be considered simultaneously. Although existing deep learning-based methods improve the visibility of low-light images, many of them tend to lose details or sacrifice naturalness. To address these issues, we present a multi-stage network for low-light image enhancement, which consists of three sub-networks. More specifically, inspired by the Retinex theory and the bilateral grid technique, we first design a reflectance and illumination decomposition network to decompose an image into reflectance and illumination maps efficiently. To increase the brightness while preserving edge information, we then devise an attention-guided illumination adjustment network. The reflectance and the adjusted illumination maps are fused and refined by adversarial learning to reduce image degradation and improve image naturalness. Experiments are conducted on our rebuilt SICE low-light image dataset, which consists of 1380 real paired images and a public dataset LOL, which has 500 real paired images and 1000 synthetic paired images. Experimental results show that the proposed method outperforms state-of-the-art methods quantitatively and qualitatively.     

基于改进MobileFaceNet的人脸识别方法北大核心

针对目前大多数人脸识别算法参数多、计算量大,难以部署到移动端和嵌入式设备中的问题,提出了一种基于改进MobileFaceNet的人脸识别方法。通过对MobileFaceNet模型结构的调整,将bottleneck模块优化为sandglass模块,改良深度卷积和逐点卷积的相对位置,适当增大sandglass模块的输出通道数,从而减少特征压缩时的信息丢失,增强人脸空间特征的提取。实验结果表明:改进后的方法在LFW测试数据集上准确率达99.15%,模型大小和计算量分别仅为原算法的61%和45%,验证了所提方法的有效性。     

Phase evolution of a novel silicon-alumina-fused mullite-containing Ti2O3 refractory at 1300 °C in N2

A novel silicon-alumina-fused mullite-containing Ti₂O₃ composite refractory is prepared and sintered in the presence of solid carbon at 1300 °C in N₂. The sintered samples exhibit a functional gradient characteristic. The phase evolution can be described as follows: Passive and active oxidation of Si to form SiO₂ and SiO to reduce the partial pressure of oxygen. SiO(g) and Si react with N₂ to form Si₃N₄ respectively. As the temperature increases and the partial pressure of oxygen decreases, Ti₂O₃ reacts with CO and N₂ to form Ti(C,N)ss, which is accompanied by the release of O₂. Si₃N₄ fixes the O₂ and reacts to form Si₂N₂O, and Si₂N₂O reacts with Al₂O₃ to form O′-Sialon, thereby realizing the transformation from Si₃N₄ to Sialon. CO and residual carbon from the pyrolysis of phenolic resin react with SiO(s) and Si to form SiC. The dense layer formed by SiC and SiO₂ blocks the diffusion of external gas to the central parts of the samples, there is still free Si which can continue to react and transform into a non-oxide reinforcing phase. In this paper, the reaction models are presented.     

Exponential Set-Point Stabilization of Underactuated Vehicles Moving in Three-Dimensional Space

This paper investigates the stabilization of underactuated vehicles moving in a three-dimensional vector space. The vehicle’s model is established on the matrix Lie group SE(3), which describes the configuration of rigid bodies globally and uniquely. We focus on the kinematic model of the underactuated vehicle, which features an underactuation form that has no sway and heave velocity. To compensate for the lack of these two velocities, we construct additional rotation matrices to generate a motion of rotation coupled with translation. Then, the state feedback is designed with the help of the logarithmic map, and we prove that the proposed control law can exponentially stabilize the underactuated vehicle to the identity group element with an almost global domain of attraction. Later, the presented control strategy is extended to set-point stabilization in the sense that the underactuated vehicle can be stabilized to an arbitrary desired configuration specified in advance. Finally, simulation examples are provided to verify the effectiveness of the stabilization controller.      

基于改进灰狼优化算法的服务功能链映射算法

随着工业互联网、车联网、元宇宙等新型互联网应用的兴起，网络的低时延、可靠性、安全性、确定性等方面的需求正面临严峻挑战。采用网络功能虚拟化技术在虚拟网络部署过程中，存在服务功能链映射效率低与部署资源开销大等问题，联合考虑节点激活成本、实例化开销，以最小化平均部署网络成本为优化目标建立了整数线性规划模型，提出基于改进灰狼优化算法的服务功能链映射（improved grey wolf optimization based service function chain mapping，IMGWO-SFCM）算法。该算法在标准灰狼优化算法基础上添加了基于无环K最短路径（K shortest path，KSP）问题算法的映射方案搜索、映射方案编码以及基于反向学习与非线性收敛改进三大策略，较好地平衡了其全局搜索及局部搜索能力，实现服务功能链映射方案的快速确定。仿真结果显示，该算法在保证更高的服务功能链请求接受率下，相较于对比算法降低了11.86%的平均部署网络成本。     

Neural Style Transfer for image within images and conditional GANs for destylization

In this paper, the feature representation of an image by CNN is used to hide the secret image into the cover image. The style of the cover image hides the content of the secret image and produce a stego image using Neural Style Transfer (NST) algorithm, which resembles the cover image and also contains the semantic content of secret image. The main technical contributions are to hide the content of the secret image in the in-between hidden layered style features of the cover image, which is the first of its kind in the present state-of-art-technique. Also, to recover the secret image from the stego image, destylization is done with the help of conditional generative adversarial networks (GANs) using Residual in Residual Dense Blocks (RRDBs). Further, stego images from different layer combinations of content and style features are obtained and evaluated. Evaluation is based on the visual similarity and quality loss between the cover-stego pair and the secret-reconstructed secret pair of images. From the experiments, it has been observed that the proposed algorithm has 43.95 dB Peak Signal-to-Noise Ratio (PSNR)), .995 Structural Similarity Index (SSIM), and .993 Visual Information Fidelity (VIF) for the ImageNet dataset. The proposed algorithm is found to be more robust against StegExpose than the traditional methods.     

非常规气藏储层改造体积评价方法研究

为精确描述非常规气藏压裂后的复杂流动特征及定量评价储层改造体积（SRV），利用自主研发的缝网重构算法“破裂树生长法”建立压后缝网模型，并以此为基础提出了使用拟稳态流动时特定的压力等值线来确定SRV范围的定量评价方法，最后以长宁201井区为例进行了矿场实例分析。该方法根据微地震监测点的位置，重构出微裂缝网的连通关系。在复杂微裂缝网的基础上建立离散裂缝地质模型并进行生产数值模拟，根据数值模拟结果的压力分布精确划定SRV的范围。利用该方法计算出长宁201井区的SRV体积为0.052 1 km3，以该缝网模型的数值模拟产量预测结果符合实际生产规律，方法实用性较好。     

Structural,elastic, phononic,optical and electronic properties investigation of two-dimensional XIS (X=Al,Ga, In) for photocatalytic water splitting

Two-dimensional (2D) materials have been widely developed due to their attractive properties. Here, by using density functional theory (DFT) calculations, for the first time, we explore potential applications of the novel XIS (X = Al, Ga, In) monolayer 2D materials on photocatalytic water splitting. A series of simulations were carried out to predict and study the structural, elastic, phononic, optical and electronic properties of 2D XIS materials. The results show that GaIS and InIS demonstrate low thermal conductivity. For optical properties, AlIS shows strong light absorption coefficients and refractive index only under ultraviolet (UV) light, while GaIS and InIS show stronger performance under both visible light and UV light with the band edge positions spanned the redox potential of water. The reasonable band positions and bandgaps make them promising photocatalysts for water splitting. This work reveals the potential applications of monolayer 2D XIS in thermal, electronic, and photocatalytic water splitting.     

“流空间”视角下的城市空间网络结构研究——以成渝双城经济圈为例

推动区域协调发展已经成为构建高质量发展国土空间布局的客观需要和解决发展不平衡问题的内在需求，以城市群为核心的经济圈建设成为驱动高质量发展的重要空间层级。为实现成渝双城经济圈的区域一体化及区域多层级协调发展，将流动的生产资源与城市空间结构相结合，基于人流、信息流、技术流、经济流四大流动资源，采用社会网络分析方法，分别从点、线、面3个维度对成渝双城经济圈空间网络结构特征进行分析。研究表明：经济圈内部呈现以成都、重庆为双核心的结构，区域间相互作用，城市中心性整体表现出内部优于外部的空间特征，核心城市对外围城市未充分发挥带动作用；圈内城市链接多表现出高度不对称性，链接对称地区主要集中在成渝中轴地区，城市间的联系有待加强，经济圈外围城市与外界联系较少；区域内部小团体现象明显，团体间联系密度存在差异，整体来看城市集群格局尚未形成，跨省域、跨地区的联系不够，成渝双城经济圈主要是西侧地区围绕成都发展。最后，为构建成渝经济圈一体化及区域多层级协调发展的空间格局，建议突破行政区域限制，构建多领域的跨区域共享协作通道；加强中部地区发展动力，提高外围城市的资源吸收能力；注重经济圈内城市交通建设及信息融合发展，突出核心城市的引领作用和外溢属性，促进城市间技术交流与经济融合。