保持视觉感知的三维树木叶片模型分治简化方法

三维树木的复杂外观形态和庞大网格数据量使得要实现精细树木模型的快速绘制十分困难.由于叶片信息在三维树木模型数据中占的比重很大,为了减少三维树木模型的数据量,提出一种保持视觉感知效果的三维树木叶片模型分治简化方法.该方法综合考虑了树叶纹理颜色和几何形状的相似性来进行相似树叶的选择与合并,并根据树木的树枝拓扑结构或树叶的空间区域分布来划分树叶简化区域,采用相应的分治策略以加速树叶的合并过程,以实现保持视觉感知特征的三维树木模型的简化.实验结果表明,文中方法能有效地减少树木模型的几何数据量,提高绘制效率,可应用于近景树木的快速逼真绘制.     

小麦加工链中重金属镉含量的深度网络预测模型

镉污染范围广、毒性大、易侵入，被认为是最具危害性的重金属之一，人长期摄入过量的镉会引起很多疾病甚至癌症。因此，在小麦加工链中预测镉元素含量的变化趋势，制定相应对策来降低其危害，具有重要的现实意义。针对小麦加工链镉含量数据含有强非线性、强随机性噪声而导致的传统建模拟合度不高等问题，本研究提出一种基于正则化方法的深度预测模型。首先，利用门控循环单元（gated recurrent unit，GRU）建立深度预测模型。其次，使用正则化方法修改模型的损失函数，通过加入噪声惩罚项来淡化训练时模型对于噪声的拟合程度，减小噪声对模型预测性能的影响。最后，使用贝叶斯优化方法进行超参数的选择，保证所建立的模型能够准确地预测小麦加工链各环节中的镉含量。本研究的预测结果表明，如果原麦中镉含量小于0.1 mg/kg，则经过加工的成品小麦粉也基本满足GB 2762—2017《食品安全国家标准 食品中污染物限量》的要求。     

An Automated Penetration Semantic Knowledge Mining Algorithm Based on Bayesian Inference

Mining penetration testing semantic knowledge hidden in vast amounts of raw penetration testing data is of vital importance for automated penetration testing. Associative rule mining, a data mining technique, has been studied and explored for a long time. However, few studies have focused on knowledge discovery in the penetration testing area. The experimental result reveals that the long-tail distribution of penetration testing data nullifies the effectiveness of associative rule mining algorithms that are based on frequent pattern. To address this problem, a Bayesian inference based penetration semantic knowledge mining algorithm is proposed. First, a directed bipartite graph model, a kind of Bayesian network, is constructed to formalize penetration testing data. Then, we adopt the maximum likelihood estimate method to optimize the model parameters and decompose a large Bayesian network into smaller networks based on conditional independence of variables for improved solution efficiency. Finally, irrelevant variable elimination is adopted to extract penetration semantic knowledge from the conditional probability distribution of the model. The experimental results show that the proposed method can discover penetration semantic knowledge from raw penetration testing data effectively and efficiently.     

基于价值特征的城市中心区步行系统建构

步行系统是城市中心区各类活动的重要空间载体，对 城市中心区人性化品质提升具有不可替代的重要作用。步行优 先是城市中心区空间营造的重要价值观。为将步行优先的价值 观系统理性地落实到具体空间要求，明确指导城市中心区空间 设计实践，提出基于“价值特征”的设计方法。价值特征是指 设计的价值观及其引领下的空间特征。基于价值特征的设计方 法是指，明确设计的价值观，并建立基于价值观的价值特征体 系，进而落实到具体设计的思路和方法。通过“价值观、空间 特征”2个层次，实现价值观在空间设计中的落实。在步行优先 价值观的引领下，建立包含“目标价值特征、本体价值特征、 支撑价值特征”的城市中心区步行系统价值特征体系，阐释其 具体价值特征内涵，提出多元价值特征耦合的设计框架，指导 步行优先的城市中心区设计实践。     

Improvement in the efficacy of dexketoprofen by its prodrug in lipid emulsion

A lipid emulsion delivery system was developed to improve the anti‐inflammatory and anti‐nociceptive activities of dexketoprofen. The dexketoprofen isopropyl ester (DE) lipid emulsion (DEE) with a particle size of 208.1 ± 33.1 nm and a charge of ?34.81 mV was administered to rats and then compared with dexketoprofen injection solution (DS). There was no statistical significance in their pharmacokinetic parameters. The anti‐inflammatory effect of DEE was evaluated by experiments involving egg‐albumin‐induced paw edema in rats and xylene‐induced ear swelling in mice. In the paw edema test, the swelling of the DEE group recovered quickly from 1 to 3 h (p<0.05), compared with the DS group. In the ear swelling test, the inhibition rate produced by DEE and DS was 57.79 and 28.57%, respectively. Acetic acid‐induced abdominal constriction and hot‐plate experiments were used to evaluate the peripheral and central anti‐nociceptive actions of DEE. In the acetic acid‐induced abdominal constriction test, DEE significantly restrained the writhing responses with a pain inhibition rate of 66.38% compared with 30.06% for the DS group. In the hot‐plate test, both preparations had a similar pain threshold increasing percentage. This study shows that the anti‐inflammatory and anti‐nociceptive activities of dexketoprofen are markedly improved after incorporation into a lipid emulsion. Practical applications: Dexketoprofen is an important drug for the management of inflammation and treatment of pain. However, its commercial preparations have usually been applied to treat diseases which are less serious because of their limited efficiencies. In this study, the anti‐inflammatory and anti‐nociceptive activities of dexketoprofen are markedly improved by incorporating its prodrug into the lipid emulsion. Therefore, the lipid emulsion preparation can be used to treat more kinds of inflammation and pain in clinic.     

基于汽车遥控门禁(RKE)系统性能及可靠性测试的研究

随着汽车越来越向智能化和人性化发展,汽车RKE无线接入技术的发展也日益成熟,并呈现出在新车市场和售后配件市场越来越普及的趋势,这一趋势所带来的规模经济效应将会使得RKE系统更具吸引力,而且会在汽车用户中越来越受欢迎.为扩大此系统在汽车市场的运用,本研究从汽车RKE系统设计原理介绍入手,对该系统性能各个项目的测试进行了研究,其中包括发射频率、发射功率、接收灵敏度、接收带宽范围、接收谐振频率、接收驻波比、遥控距离以及可靠性测试等主要性能指标,以期为广大汽车用户提供性能可靠的汽车遥控门禁系统.     

城市用地“3D”发展模式研究——一种基于减少机动化需求的规划理念

基于我国当前城市空间蔓延、功能分区单一以及"以车为本"的场所设计带来的个体机动化出行增加、公共交通效率低下、步行环境欠佳等问题,提出需要建立沿公交走廊的密度点轴结合发展(density)、用地混合多元布局(diversity)以及步行友好场所设计(design)的用地"3D"发展模式,以减少机动化出行需求。在此思路下,借鉴香港地区轨道沿线用地发展经验,研究香港实现"3D"模式的具体方法与措施,并以广州花都CBD为例,运用"3D"理念,对花都CBD内轨道沿线的用地密度、混合度、场所进行规划设计,以探索城市用地"3D"发展模式在我国发展的适应性。     

激光修整青铜金刚石砂轮石墨变质层的研究

针对声光调Q YAG脉冲激光修整青铜结合剂金刚石砂轮,运用ANSYS有限元软件建立了三维脉冲激光烧蚀金刚石磨粒的数学模型和传热模型,得到了激光烧蚀金刚石磨粒后的温度分布。利用所建立的模型可获得不同激光参数下的变质层厚度,并通过实验对该模型进行了验证。针对脉冲激光修锐与整形的两个不同方面,从实验和数值模拟两方面研究脉冲激光参数对变质层厚度的影响规律,得到在修锐时脉宽与激光功率对变质层厚度影响程度相差不大,而在整形时脉宽则起到了绝对的主导作用;经过多脉冲激光烧蚀后变质层厚度有所减小;只有在砂轮修锐时石墨变质层厚度随脉宽的增加而减少。     

APT攻击场景重构方法综述

APT攻击已经成为网络安全的重要威胁之一,从大量告警日志数据中识别APT攻击并还原攻击场景已成为当前急需研究的问题。首先介绍了攻击场景重构基本概念和技术流程框架。其次,依据采用的关联分析方法,对攻击场景重构方法进行了分类,并分别综述了基于经验知识、基于因果关系、基于语义相似性和基于机器学习4类方法的基本步骤和具体案例。最后,讨论了不同方法的优势和不足,结合最新技术应用指出了未来发展趋势。     

面向电网削峰的商业楼宇空调负荷调控实证研究

伴随各类空调的广泛应用,空调负荷快速增长,已占夏季尖峰负荷的30%以上,电网峰谷差进一步拉大,加剧了电网高峰负荷供应缺口,影响电网的安全稳定运行。基于商业楼宇空调负荷具有较大可控性,开展了面向电网削峰的商业楼宇空调负荷调控实证研究,验证商业楼宇空调负荷调控技术实现电网削峰的可行性及其效果,为规模化推广空调负荷调控储备必要的技术和经验。