基于链接路径预测的聚焦Web实体搜索

实体搜索是一个有前景的研究领域,因为它能够为用户提供更为详细的Web信息.快速、完全地收集特定领域实体所在的网页是实体搜索中的一个关键问题.为了解决这个问题,将Web网站建模为一组互连的状态构成的图,提出一种链接路径预测学习算法LPC,该模型能够学习大型网站中从主页通向目标网页的最优路径,从而指导爬虫快速定位到含有Web实体的目标网页.LPC算法分为两个阶段：首先,使用概率无向图模型CRF,学习从网站主页通往目标网页的链接路径模型,CRF模型能够融合超连接和网页中的各种特征,包括状态特征和转移特征;其次,结合增强学习技术和训练的CRF模型对爬行前端队列的超链接进行优先级评分.一种来自增强学习的折扣回报方法通过利用路径分类阶段学习的CRF模型来计算连接的回报值。在多个领域大量真实数据上的实验结果表明,所提出的适用CRF模型指导的链接路径预测爬行算法LPC的性能明显优于其他聚焦爬行算法.     

集热方式对全玻璃真空管太阳能热水器性能的影响

为对比分析自然循环竖排管、强制循环竖排管和强制循环横排管3种集热方式对全玻璃真空管太阳热水器有效集热量、平均有效集热效率和瞬时有效集热量等的影响,以3组30支Φ58×1800 mm的全玻璃真空管太阳热水器为研究对象,在兰州地区搭建试验平台,在太阳辐射为19.0～25.7 MJ/m2,风速为0.5～1.3m/s,平均环境...     

Digital twin-based framework for wireless multimodal interactions over long distance

Wireless multimodal interactions over long distance (WMILD) would give rise to numerous thrilling applications, such as remote touching and immersive teleoperations. However, long distances can induce large propagation delays, which makes it difficult to meet the ultra-low latency requirements in haptic-visual interactions. Considering existing works mainly focused on the wireless access part, this paper designs an end-to-end framework for general WMILD applications based on the digital twin (DT) technology and proposes an intelligent resource allocation and parameter compression scheme to guarantee WMILD performance under constraint network resources. In the framework, user device can acquire real-time remote interactions by performing local interactions with nearby base station (BS), where a DT of the remote side is deployed to predict the remote haptic-visual feedbacks. A reliable DT updating process is carefully designed to guarantee the DT accurately model its dynamic physical counterpart. To optimize the updating reliability, we formulate the resource allocation and parameter compression to be a constraint-Markov decision problem, under the constraints on energy consumption, multimodal interactions and updating latencies. Then, a safe deep reinforcement learning algorithm is proposed to adapt resources and compression according to the dynamic DT updating workload, multimodal data-streams and remote transmission capacities. Simulation shows the framework can achieve high updating reliability compared with baselines.     

Effect of Tooling Temperature on the Transient Lubricant Behavior in Hot Metal Forming Processes

In hot metal forming processes, the temperature of the forming tool progressively increases under serial production conditions. Water-based two-phase lubricants may be applied to cool the forming tool and moderate temperature, in which the liquid agent would evaporate or decompose rapidly with dry matter deposited on the tooling surface during the dwelling time before the forming process commences. Herein, an interactive friction model for a two-phase lubricant is developed to predict the transient lubricant behaviors, i.e., predicting the effects of tool temperature and dwelling time on the friction coefficient evolution and lubricant breakdown. Friction tests between a warm pin and hot aluminum workpiece are conducted using the advanced friction testing system, TriboMate, to validate the modeling results.     

Phenyl Selenide-Based Precursors as Hydrogen Peroxide Inducible DNA Interstrand Cross-Linkers

DNA interstrand crosslinks (ICLs) are highly toxic DNA lesions, and induce cell death by blocking DNA strand separation. Most ICL agents aiming to kill cancer cells, also generate adverse side effects to normal cells. H₂O₂-inducible DNA ICL agents are highly selective for targeting cancer cells, as the concentration of H₂O₂ is higher in cancer cells than normal cells. Previous studies have focused on arylboronate-based precursors, reacting with H₂O₂ to generate reactive quinone methides (QMs) crosslinking DNA. Here we explore phenyl selenide-based precursors 1 – 3 as H₂O₂-inducible DNA ICL agents. The precursors 1 – 3 can be activated by H₂O₂ to generate the good benzylic leaving group and promote production of reactive QMs to crosslink DNA. Moreover, the DNA cross-linking ability is enhanced by the introduction of substituents in the para-position of the phenolic hydroxyl group. From the substituents explored (H, OMe, F), the introduction of electron donating group (OMe) shows a pronounced elevating effect. Further mechanistic studies at the molecular and DNA levels confirm alkylation sites located mainly at dAs, dCs and dGs in DNA. Additionally, cellular experiments reveal that agents 1 – 3 exhibit higher cytotoxicity toward H1299 human lung cancer cells compared to clinically used drugs, by inducing cellular DNA damage, apoptosis and G0/G1 cell cycle arrest. This study provides a strategy to develop H₂O₂-inducible DNA interstrand cross-linkers.     

Hydrogen Peroxide-Inducible PROTACs for Targeted Protein Degradation in Cancer Cells

Proteolysis-targeting chimeras (PROTACs) provide a powerful technique to degrade targeted proteins utilizing the cellular ubiquitin-proteasome system. The major concern is the host toxicity resulting from their poor selectivity. Inducible PROTACs responding to exogenous stimulus, such as light, improve their specificity, but it is difficult for photo-activation in deep tissues. Herein, we develop H₂O₂-inducible PROTAC precursors 2 / 5 , which can be activated by endogenous H₂O₂ in cancer cells to release the active PROTACs 1 / 4 to effectively degrade targeted proteins. This results in the intended cytotoxicity towards cancer cells while targeted protein in normal cells remains almost unaffected. The higher Bromodomain-containing protein 4 (BRD4) degradation activity and cytotoxicity of 2 towards cancer cells is mainly due to the higher endogenous concentration of H₂O₂ in cancer cells (A549 and H1299), characterized by H₂O₂-responsive fluorescence probe 3 . Western blot assays and cytotoxicity experiments demonstrate that 2 degrades BRD4 more effectively and is more cytotoxic in H₂O₂-rich cancer cells than in H₂O₂-deficient normal cells. This method is also extended to estrogen receptor (ER)-PROTAC precursor 5 , showing H₂O₂-dependent ER degradation ability. Thus, we establish a novel strategy to induce targeted protein degradation in a H₂O₂-dependent way, which has the potential to improve the selectivity of PROTACs.     

Hf对一种镍基高硼铸造高温合金凝固行为及疏松情况的影响

研究了Hf的添加对一种镍基高硼铸造高温合金显微组织、凝固行为、疏松情况的影响。显微组织分析、差热分析(DSC)、等温凝固淬火试验结果显示,Hf在合金的凝固过程中强烈偏析于枝晶间区域,并在凝固末期以Ni5Hf相的形式从残余液相中析出；Hf的加入降低了合金的液/固相线温度、γ/γ′共晶相和硼化物析出温度,延缓了合金的凝固过程,加宽了凝固温度范围,显著增大了γ/γ′共晶相的含量。自主设计并浇铸一种薄壁管铸件,渗透检验结果显示Hf的加入使得薄壁管的疏松明显减少,合金的疏松倾向性显著降低。