风景园林与绿色基础设施在城市流域水资源规划中的重要作用

通过绿色基础设施途径,处理美国波士顿北部的马萨诸塞州城市流域的水资源规划问题。从多个尺度为风景园林师提供水资源规划的经验与启发,探究公众对新型绿色基础设施解决方案的态度与偏好,以及公众偏好对于整体规划设计的重要作用。     

Application of a Novel Method for Machine Performance Degradation Assessment Based on Gaussian Mixture Model and Logistic Regression

The currently prevalent machine performance degradation assessment techniques involve estimating a machine’s current condition based upon the recognition of indications of failure features,which entail complete data collected in different conditions.However,failure data are always hard to acquire,thus making those techniques hard to be applied.In this paper,a novel method which does not need failure history data is introduced.Wavelet packet decomposition(WPD) is used to extract features from raw signals,principal component analysis(PCA) is utilized to reduce feature dimensions,and Gaussian mixture model(GMM) is then applied to approximate the feature space distributions.Single-channel confidence value(SCV) is calculated by the overlap between GMM of the monitoring condition and that of the normal condition,which can indicate the performance of single-channel.Furthermore,multi-channel confidence value(MCV),which can be deemed as the overall performance index of multi-channel,is calculated via logistic regression(LR) and that the task of decision-level sensor fusion is also completed.Both SCV and MCV can serve as the basis on which proactive maintenance measures can be taken,thus preventing machine breakdown.The method has been adopted to assess the performance of the turbine of a centrifugal compressor in a factory of Petro-China,and the result shows that it can effectively complete this task.The proposed method has engineering significance for machine performance degradation assessment.     

Fluid-based Slotting Optimization for Automated Order Picking System with Multiple Dispenser Types

Slotting strategy heavily influences the throughput and operational cost of automated order picking system with multiple dispenser types, which is called the complex automated order picking system (CAOPS). Existing research either focuses on one aspect of the slotting optimization problem or only considers one part of CAOPS, such as the Low-volume Dispensers, to develop corresponding slotting strategies. In order to provide a comprehensive and systemic approach, a fluid-based slotting strategy is proposed in this paper. The configuration of CAOPS is presented with specific reference to its fast-picking and restocking subsystems. Based on extended fluid model, a nonlinear mathematical programming model is developed to determine the optimal volume allotted to each stock keeping unit (SKU) in a certain mode by minimize the restocking cost of that mode. Conclusion from the allocation model is specified for the storage modules of high-volume dispensers and low-volume dispensers. Optimal allocation of storage resources in the fast-picking area of CAOPS is then discussed with the aim of identifying the optimal space of each picking mode. The SKU assignment problem referring to the total restocking cost of CAOPS is analyzed and a greedy heuristic with low time complexity is developed according to the characteristics of CAOPS. Real life application from the tobacco industry is presented in order to exemplify the proposed slotting strategy and assess the effectiveness of the developed methodology. Entry-item-quantity (EIQ) based experiential solutions and proposed-model-based near-optimal solutions are compared. The comparison results show that the proposed strategy generates a savings of over 18% referring to the total restocking cost over one-year period. The strategy proposed in this paper, which can handle the multiple dispenser types, provides a practical quantitative slotting method for CAOPS and can help picking-system-designers make slotting decisions efficiently and effectively.     

生物软组织切割过程建模

自行设计和制造了一台可对切割力和刀具位移进行实时测量的生物软组织切割装置,并对猪主动脉壁组织开展了切割实验,对其切割特性进行了分析。切割力在组织未被切破之前随刀具位移非线性增大,呈典型的J形曲线关系;当切割力增大到一定程度时,组织被切破,切割力迅速减小;随后切割过程相对比较平稳,切割力在较小的范围内波动,呈现增大-减小的波浪形式。整个切割过程可被分为三个阶段：变形阶段、破裂阶段和切割阶段。根据能量平衡对切割过程中各个阶段能量之间的转换关系进行分析,并建立了各个切割阶段的切割力模型。在变形阶段,切割力表现为典型的非线性J形曲线关系,一个指数函数被用于拟合变形阶段的切割力;在切割阶段,根据能量平衡方程建立了切割力模型;而对于破裂阶段,由于时间非常短,切割力由破裂时的切割力直线减小。比较发现,模型所得切割力能够很好地与实验所得切割力吻合,证明切割力模型是正确的。     

Exploring the deep biosphere

Over the past two decades, scientific drilling into sediments and rocks in the ocean and the continent has revealed the presence of physiologically and phylogenetically complex microbial life in the deep subsurface. Microorganisms, most of which have no cultured or known relatives in the surface biosphere, have been discovered in sediments and rock at depth as deep as 1 km below the seafloor and more than 3 km deep in the continent. The deep biosphere probably represents the most voluminous part of the glob...     

绿色空间对呼吸健康的影响研究综述及综合分析框架

绿色空间具备重要的健康干预作用,其中对呼吸系统的健康影响逐渐受到关注。基于Web of Science核心数据库,遴选了2000—2020年针对绿色空间与呼吸健康相关关系开展实证研究的英文文献,采用文献计量方法探析知识网络关系现状;辨析了聚合性和个体性2类研究的主要特点。研究发现2类研究均缺乏纵向维度分析和影响路径分析;同时,城镇整体层面的研究采用的绿色空间测度指标单一,城镇内部层面的研究对微观层面绿色空间特征的关注均显不足等。基于此,建构了一个绿色空间对呼吸健康影响的综合分析框架,并提出未来研究可拓展的分析对象、测度指标和分析方法。     

景观再造：面向新环境现实的新兴景观设计实践与教学

工业与制造业中心可以被看作更宜居和可持续的大都市工业景观的一部分,是地方和全球经济不断变化的场所以及解决能源、废弃物、代谢物问题的创造性的环境。重点介绍了“第五次工业革命”——一种当代景观的系统性转型：它将资源、治理结构、公民社会、人类认同、自然意义的变化与新的加工制造方法在2个尺度上相结合。这2个尺度包括：1）景观规划尺度,涉及与城市肌理相关的后石油经济工业区;2）景观设计尺度,涉及工业生态、垃圾填埋场、一系列的公共和社区开放空间以及景观中的能源利用。创造性地提出一种方法,即通过一系列立足于为自然环境和现代建成环境的未来提供多样选择的景观教学法,来探讨传统和现代的规划、设计、文化以及技术等主题。     

Influence of solar wind dynamic pressure on geomagnetic Dst index during various magnetic storms

The Dst index,designed as a proxy of ring current intensity,is known to be also affected by other magnetospheric current systems,e.g.magnetopause current.The pressure-corrected Dst index is obtained by removing the effects of the solar wind dynamic pressure and the quiet time ring current.However,all previous studies treated the correction coefficient as an averaged parameter for storms of different intensity.In this paper,based on the Burton's equations and employing two independent methods,we will show a ...     

The thermal performance of a Roof-Pond integrated to a building for heating during Cold-Winter Desert climate conditions in Saudi Arabia

This study reports an experiment to investigate the feasibility of a passive heating roof-pond system on an existing room in the cold winter conditions of Riyadh, Saudi Arabia. Statistical analyses of data recorded during the winter season of 1996–97, are carried out to evaluate the thermal peformance of the proposed system. Total effective heating and the heating power of the roof pond system are computed and analysed. Results indicate that the roof-pond system is capable of maintaining warm indoor air temperature conditions. The statistical formulae for this system are presented and used to estimate the indoor daily average air Dry Bulb Temperature (DBT_Avg-indoor] created by the system. Validation of the proposed formulae is also presented.     

Creep and tensile properties of press molding joined GMT-sheets

GMT-sheet is used in automobile bumper with high rigidity and strength, and its joining strength is influenced by lap length, one of the joined molding conditions. Fracture strength was calculated by dividing fracture load with cross-sectional area. Total five repeated measurements were made to obtain the average value. Tensile test was conducted at room temperature for 10 specimens. In addition, the effect of compression ratio on creep and tensile performance during lap joined molding was discussed. With increasing lap length, the lap joining efficiency of GMT-sheet was increased. However, higher compression ratio reduced the joining efficiency. Creep test on GMT-sheet showed abrupt fracture without tertiary creep. This can be explained by the weak thermal resistance of the resin. If GMT-sheet was exposed to high temperature for a long time, it was easily failed by external force.