减水剂类型对赤泥—矿渣基地聚物注浆材料性能的影响及机理研究

针对赤泥等固体废弃物对环境危害性大且利用率低等问题,以碱激发赤泥-矿渣基地聚物注浆材料为 研究对象,研究了不同掺量的聚羧酸(PA)减水剂、醛酮缩合物(AKC)减水剂和萘系(N)减水剂对材料凝结时间、流动 性及强度等的影响,并通过 XRD、傅里叶红外光谱及 SEM 等设备对减水剂的作用机理进行研究。 结果表明:减水剂增 强了材料的流动性但降低了材料的剪切应力;N 和 PA 减水剂能缩短材料的凝结时间,但 AKC 减水剂会延长材料的凝 结时间;N 和 AKC 减水剂能提高材料的强度,但 PA 减水剂会降低材料的强度;N 减水剂对材料的综合性能提升效果 更加明显,其最优掺量为 0. 7%;减水剂对赤泥-矿渣基地聚物性能提升的作用机理主要是促进地聚合物凝胶的形成。 研究成果为拓展赤泥在工程上的使用途径和效率提供了理论指导。     

Spatiotemporal Magnetocaloric Microenvironment for Guiding the Fate of Biodegradable Polymer Implants

The degradation behavior of implants is significantly important for bone repair. However, it is still unprocurable to spatiotemporally regulate the degradation of the implants to match bone ingrowth. In this paper, a magneto-controlled biodegradation model is established to explore the degradation behavior of magnetic scaffolds in a magnetothermal microenvironment generated by an alternating magnetic field (AMF). The results demonstrate that the scaffolds can be heated by magnetic nanoparticles (NPs) under AMF, which dramatically accelerated scaffold degradation. Especially, magnetic NPs modified by oleic acid with a better interface compatibility exhibit a greater heating efficiency to further facilitate the degradation. Furthermore, the molecular dynamics simulations reveal that the enhanced motion correlation between magnetic NPs and polymer matrix can accelerate the energy transfer. As a proof-of-concept, the feasibility of magneto-controlled degradation for implants is demonstrated, and an optimizing strategy for better heating efficiency of nanomaterials is provided, which may have great instructive significance for clinical medicine.     

Relationships among boredom proneness,sensation seeking and smartphone addiction among Chinese college students: Mediating roles of pastime,flow experience and self-regulation

Smartphones are indispensable for many young people, which in turn increases the risk of smartphone addiction. Previous studies have discovered significant and positive influences of boredom proneness, sensation seeking and smartphone addiction. This study further explored these influences, their underlying mechanisms, and the mediating effects of pastime, flow experience and self-regulation on smartphone addiction. A total of 442 Chinese college students completed a survey focusing on boredom proneness, sensation seeking, pastime, flow experience, self-regulation and smartphone addiction. The results indicated that boredom proneness positively affects smartphone addiction. Contrary to expectations, the results showed that there is no significant relationship between sensation seeking and smartphone addiction. Moreover, pastime and self-regulation have partial mediation effects on the relationship between boredom proneness and smartphone addiction, while the effect of sensation seeking on smartphone addiction is completely transmitted with the help of flow experience and self-regulation. The findings and their implications are discussed.     

基于查询的新闻多文档自动摘要技术研究

针对新闻文本领域,该文提出一种基于查询的自动文本摘要技术,更加有针对性地满足用户信息需求。根据句子的TF-IDF、与查询句的相似度等要素,计算句子权重,并根据句子指示的时间给定不同的时序权重系数,使得最近发生的新闻内容具有更高的权重,最后使用最大边界相关的方法选择摘要句。通过与基于TF-IDF、Text-Rank、LDA等六种方法的对比,该摘要方法ROUGE评测指标上优于其他方法。从结合评测结果及摘要示例可以看出,该文提出的方法可以有效地从新闻文档集中摘取核心信息,满足用户查询内容的信息需求。     

Learning search keywords for construction procurement

Seeking information from websites has become an essential part of a contractor's procurement undertaking, as more and more procurement websites become available on the Internet. Websites host extremely large amounts of information; a keyword search, therefore, is often more efficient than browsing via an index. However, in order to find the desired information, it may be necessary to enter keywords using a trial-and-error process. This research recognizes that professional procurement experience can help users search website information more effectively, by using fewer keywords, and so proposes a learning model and suggestion model that can capture such experience, thus guiding inexperienced users in their search. Experiments, evaluating the performance of the system, were also conducted.     

Handling variety: the tension between adaptability and interoperability of open source software

Open source software (OSS) offers unprecedented opportunities to create variety. This could lead to incompatibility and fragmentation. To prevent this some form of coordination is needed. This paper explores which mechanisms of coordination are responsible for limiting divergence in OSS. Two cases are examined: Java and Linux.A systematic difference seems to exist between the mechanisms identified in the two communities. With respect to Java, divergence is where possible avoided ex ante, whereas for Linux divergence is foremost reduced ex post. The conclusion discusses this difference and the implications of both types of coordination in respect to interoperability.     

景区休闲度假房地产价值的构成及其分摊管理

景区休闲度假房地产价值的形成包括成本构成和市场构成，通过对成本构成和市场构成的分析，两个方面都有资源的贡献。我国各种旅游资源的产权一般为国家所有，对旅游资源贡献就需要在房地产的投资者和资源的所有者之间进行分摊。提出了旅游房地产的成本构成和市场构成，并提出了旅游资源贡献分摊的概念，并通过实例分析了景区贡献的计算及其分摊，在理论上和实践上完善了我国的房地产价格管理体系。     

基于区块链的电子医疗病历可控共享模型

电子医疗病历共享能够提高医疗诊断的准确性, 促进公共医疗领域的发展. 针对目前普遍存在的不同医院之间病历共享困难、病人无法掌握其病历的使用情况等问题, 本文提出了病人可控、云链协同的病历共享模型. 各级医院组成联盟区块链, 病历数据实行链上、链下混合存储. 病历共享模型利用聚类算法, 改进实用拜占庭共识算法, 使得各节点可以更高效地达成共识. 将基于属性的加密方案与多关键词加密方案结合进行病历加密, 实现了数据可控共享, 病人可自主定义访问策略, 同时用户可以对加密病历进行安全、精确检索. 考虑到用户属性的动态更新, 本文设计了属性更新子协议. 最后评估了模型的安全性和性能, 并分析了模型的优劣势.     

Pricing Exotic Option Under Jump-Diffusion Models by the Quadrature Method

This paper extends the quadrature method to price exotic options under jump-diffusion models. We compute the transition density of jump-extended models using convolution integrals. Furthermore, a simpler and more efficient lattice grid is introduced to implement the recursion more directly in matrix form. It can be shown that a lot of running time can be saved. At last, we apply the developed approach to the different jump-extended models to demonstrate its universality and provide a detailed comparison for the discrete path-dependent options to demonstrate its advantages in terms of speed and accuracy.

     

An adaptive updating protocol for reducing moving object database workload

In the last decade, spatio-temporal database research focuses on the design of effective and efficient indexing structures in support of location-based queries such as predictive range queries and nearest neighbor queries. While a variety of indexing techniques have been proposed to accelerate the processing of updates and queries, not much attention has been paid to the updating protocol, which is another important factor affecting the system performance. In this paper, we propose a generic and adaptive updating protocol for moving object databases with less number of updates between objects and the database server, thereby reducing the overall workload of the system. In contrast to the approach adopted by most conventional moving object database systems where the exact locations and velocities last disclosed are used to predict their motions, we propose the concept of Spatio-temporal safe region to approximate possible future locations. Spatio-temporal safe regions provide larger space of tolerance for moving objects, freeing them from location and velocity updates as long as the errors remain predictable in the database. To answer predictive queries accurately, the server is allowed to probe the latest status of objects when their safe regions are inadequate in returning the exact query results. Spatio-temporal safe regions are calculated and optimized by the database server with two contradictory objectives: reducing update workload while guaranteeing query accuracy and efficiency. To achieve this, we propose a cost model that estimates the composition of active and passive updates based on historical motion records and query distribution. More system performance improvements can be obtained by cutting more updates from the clients, when the users of system are comfortable with incomplete but accuracy bounded query results. We have conducted extensive experiments to evaluate our proposal on a variety of popular indexing structures. The results confirm the viability, robustness, accuracy and efficiency of our proposed protocol.