基于CEEMD的重大事件对香港住宅价格影响的实证分析

应用互补集成经验模态分解（CEEMD）方法对香港1997―2018年的住宅价格月度数据进行了分解，将经过重构后的数据分成高频序列、低频序列与残差项。将BP多断点检测应用于低频序列，并结合样本时段内的重大事件进行实证分析。结果表明：1997年亚洲金融风暴对房价的影响大于2008年金融危机；外部经济体的救市政策间接地影响香港房价；在经济不景气的大环境下“孙九招”政策没有立即见效；资本投资者入境计划、住房供给调整与按揭贷款调整对房价的影响较为显著；税收调整对房价影响不显著、对交易量影响显著；SARS爆发使住宅价格下降约1%。     

Enhanced conformational sampling method for proteins based on the TaBoo SeArch algorithm: Application to the folding of a mini‐protein,chignolin

The conformational samplings are indispensible for obtaining reliable canonical ensembles, which provide statistical averages of physical quantities such as free energies. However, the samplings of vast conformational space of biomacromolecules by conventional molecular dynamics (MD) simulations might be insufficient, due to their inadequate accessible time‐scales for investigating biological functions. Therefore, the development of methodologies for enhancing the conformational sampling of biomacromolecules still remains as a challenging issue in computational biology. To tackle this problem, we newly propose an efficient conformational search method, which is referred as TaBoo SeArch (TBSA) algorithm. In TBSA, an inverse energy histogram is used to select seeds for the conformational resampling so that states with high frequencies are inhibited, while states with low frequencies are efficiently sampled to explore the unvisited conformational space. As a demonstration, TBSA was applied to the folding of a mini‐protein, chignolin, and automatically sampled the native structure (C_α root mean square deviation < 1.0 Å) with nanosecond order computational costs started from a completely extended structure, although a long‐time 1‐µs normal MD simulation failed to sample the native structure. Furthermore, a multiscale free energy landscape method based on the conformational sampling of TBSA were quantitatively evaluated through free energy calculations with both implicit and explicit solvent models, which enable us to find several metastable states on the folding landscape. © 2015 Wiley Periodicals, Inc.     

物理化学教学中安全工程教育的融合与内化实例*

如何强化安全工程教育是化学化工类专业高等教育的一个重要课题。通过对蒸汽锅炉爆炸、火灾爆燃事故以及锈蚀危害等3个实例的详细讲述,指出在物理化学的教学中,若适时融入相关的安全工程教育,可以使学生深刻理解安全事故发生及防范所依赖的物理化学原理,从而起到安全意识的内化作用。教学中现代教育技术的引入可以增强这一效果。     

阿拉尔垦区自然灾害对农业经济影响的研究

阿拉尔垦区是新疆重要的棉花、林果产业基地,然而频发的自然灾害给农业经济造成了极为严重的影响.自然灾害发生频率高、灾害地域分布不均衡以及带来的破坏效果大和损失严重等特点,引起了人们的广泛关注.采用层次分析法作为基础理论,通过专家打分法确定权重建立评价模型.阿拉尔垦区自然灾害对农业经济影响的研究是一个非常重要的理论和实践问题,它对于提高农民收入、促进农业可持续发展和社会稳定具有重要的意义.     

Structural dissimilarity sampling with dynamically self‐guiding selection

Structural dissimilarity sampling (SDS) has been proposed as an enhanced conformational sampling method for reproducing the structural transitions of a given protein. SDS consists of cycles of two steps: (1) Selections of initial structures with structural dissimilarities by referring to a measure. (2) Conformational resampling by restarting short‐time molecular dynamics (MD) simulations from the initial structures. In the present study, an efficient measure is proposed as a dynamically self‐guiding selection to accelerate the structural transitions from a reactant state to a product state as an extension to the original SDS. In the extended SDS, the inner product (IP ) between the reactant and the snapshots generated by short‐time MD simulations are evaluated and ranked according to the IP s at every cycle. Then, the snapshots with low IP s are selected as initial structures for the short‐time MD simulations. This scheme enables one to choose dissimilar and distant initial structures from the reactant, and thus the initial structures dynamically head towards the product, promoting structural transitions from the reactant. To confirm the conformational sampling efficiency, the extended SDS was applied to maltodextrin binding protein (MBP), and we successfully reproduced the structural transition from the open to closed states with submicrosecond‐order simulation times. However, a conventional long‐time MD simulation failed to reproduce the same structural transition. We also compared the performance with that obtained by the ordinary SDS and other sampling techniques that have been developed by us to characterize the possible utility of the extended SDS for actual applications. © 2017 Wiley Periodicals, Inc.     

Adaptive‐numerical‐bias metadynamics

A metadynamics scheme is presented in which the free energy surface is filled with progressively adding adaptive biasing potentials, obtained from the accumulated probability distribution of the collective variables. Instead of adding Gaussians with assigned height and width in conventional metadynamics method, here we add a more realistic adaptive biasing potential to the Hamiltonian of the system. The shape of the adaptive biasing potential is adjusted on the fly by sampling over the visited states. As the top of the barrier is approached, the biasing potentials become wider. This decreases the problem of trapping the system in the niches, introduced by the addition of Gaussians of fixed height in metadynamics. Our results for the free energy profiles of three test systems show that this method is more accurate and converges more quickly than the conventional metadynamics, and is quite comparable (in accuracy and convergence rate) with the well‐tempered metadynamics method. © 2017 Wiley Periodicals, Inc.     

突发事件下应急物资多目标优化调度模型与算法研究：以新冠肺炎疫情为例

突发事件下应急物资调度具有高度不确定性与动态性,应急物资跨区域调度计划能否科学合理制定对应急救援的有效开展具有重要影响。以武汉市新冠肺炎疫情为例,考虑应急物资跨区域调配的时效差异、地域分散以及资金消耗等要素,建立多周期下包含软硬需求时间窗约束的多物资品种、运输方式的跨区域三级动态物资调度网络模型,并设计一种带变异操作的动态变惯性权重自适应粒子群算法(VDCWPSO),利用疫情算例验证该算法的有效性和可行性。研究结果表明,在保障应急物资供应时效性、公平性、经济性原则下,物资跨区域调度可以缓解资源严重短缺状况、提高医用物资利用率,研究可为突发事件下应急物资调度计划的制定与动态调整提供决策支持。     

中国活动构造与环境灾害研究中的若干重大问题

活动构造与环境灾害是密切相关的。活动构造可以直接引起地质灾害,构造活动引发的地震又可以派生出一系列地质灾害,人类不恰当的工程活动还可以恶化地质构造环境而加剧地质灾害。在活动构造与环境灾害相关性研究方面,我国急待启动四大科学问题的研究工作:基于现代大陆动力学的中国大陆区域地壳稳定性分区评价研究;青藏高原隆升与地质灾害;活动断裂的工程危害及其防治;地质灾害的内外动力耦合成因机理。     

吹吸扰动对壁湍流相干结构的影响

采用热线风速仪测量受吹吸扰动的壁湍流边界层的流向速度，用傅里叶变换和子波变换研究 吹吸扰动对壁湍流能谱的影响，结果显示施加的低频扰动使边界层内层大尺度结构的能量减 少，小尺度结构的能量有所增强，远离壁面时扰动强度逐步衰减直到在外层中消失；通过VITA 法和子波变换法检测猝发事件，表明该扰动降低了猝发强度，使猝发周期延长，条件平均速 度波形的幅值降低、持续时间变短，说明扰动明显抑制了相干结构的猝发过程. 利用子波变 换可以实现湍谱分析，能有效检测猝发中的湍流结构，是一种客观的分析工具.     

人为地质灾害和地质环境

本文论述了人为地质灾害的概念, 典型事例以及人为地质灾害与地质环境的相互关系。指出, 人为地质灾害是由于人类的工程经济活动而引起的地质灾害。人为地质灾害可导致地质环境恶化, 使环境质量下降；而地质环境恶化又可导致地质灾害的加重, 使灾害频度增大, 强度增高。