Classification by clustering decision tree-like classifier based on adjusted clusters

Currently cluster analysis techniques are used mainly to aggregate objects into groups according to similarity measures. Whether the number of groups is pre-defined (supervised clustering) or not (unsupervised clustering), clustering techniques do not provide decision rules or a decision tree for the associations that are implemented. The current study proposes and evaluates a new technique to define decision tree based on cluster analysis. The proposed model was applied and tested on two large datasets of real life HR classification problems. The results of the model were compared to results obtained by conventional decision trees. It was found that the decision rules obtained by the model are at least as good as those obtained by conventional decision trees. In some cases the model yields better results than decision trees. In addition, a new measure is developed to help fine-tune the clustering model to achieve better and more accurate results.     

Modulating the Mechanical Performance of Macroscale Fibers through Shear‐Induced Alignment and Assembly of Protein Nanofibrils

Protein‐based fibers are used by nature as high‐performance materials in a wide range of applications, including providing structural support, creating thermal insulation, and generating underwater adhesives. Such fibers are commonly generated through a hierarchical self‐assembly process, where the molecular building blocks are geometrically confined and aligned along the fiber axis to provide a high level of structural robustness. Here, this approach is mimicked by using a microfluidic spinning method to enable precise control over multiscale order during the assembly process of nanoscale protein nanofibrils into micro‐ and macroscale fibers. By varying the flow rates on chip, the degree of nanofibril alignment can be tuned, leading to an orientation index comparable to that of native silk. It is found that the Young's modulus of the resulting fibers increases with an increasing level of nanoscale alignment of the building blocks, suggesting that the mechanical properties of macroscopic fibers can be controlled through varying the level of ordering of the nanoscale building blocks. Capitalizing on strategies evolved by nature, the fabrication method allows for the controlled formation of macroscopic fibers and offers the potential to be applied for the generation of further novel bioinspired materials.     

Achieving Construction Innovation through Academia-Industry Cooperation—Keys to Success

The conception, development, implementation, and commercialization of a crane-mounted vision system through close academia-industry cooperation illustrate how such joint efforts can yield research and development success. The vision system was devised to help solve the problem of blind lifts and other viewing concerns related to the operation of tower cranes on construction sites, thereby enhancing safety and productivity and saving money. In addition to other expected difficulties, the project faced the traditional skepticism of a conservative industry reluctant to adopt changes. The paper relays the chronology of the project and analyzes, stage by stage, the steps taken by the university-based developers to work in harmony with construction companies in particular, and with the industry at large, to ensure success. Lessons drawn from this experience are offered to future academician developers in the field of construction technology.     

Systematic Evaluation of Construction Equipment Alternatives: Case Study

Selecting the right equipment for the project is inherently a multifaceted cost and benefit evaluation process that is further compounded by the complexity of today’s building projects and the lack of systematic tools for the consideration of soft factors. This paper presents a detailed application example of a model based on an analytical hierarchy process (AHP) approach. This model was developed to address the difficulties experienced during the multifaceted process. The example illustrates how an AHP-based model helps address the multitude of qualitative, intangible factors, both among the factors themselves and then vis-à-vis costs, by means of a systematic and traceable process. The method enables project managers and their equipment selection teams to exercise their knowledge, intuition, and professional judgment, and at the same time to address the context and specifics of the particular projects under examination. The example should be helpful for construction practitioners dealing with similar equipment selection issues. Researchers may find interest in the implementation of a multiattribute-decision-making method for a typical construction management problem.     

AHP-Based Weighting of Factors Affecting Safety on Construction Sites with Tower Cranes

Aspiring to adopt a nonstatistical quantitative approach to safety assessment, this study implements a multiattribute decision-making tool to elicit knowledge from experts and formalize it into a set of weighted safety factors. The environment addressed is the construction site and the specific factors studied are those affecting safety due to the operation of tower cranes. Nineteen senior construction equipment and safety experts were interviewed and led through the analytic hierarchy process (AHP) to provide their assessments on the relative importance of safety factors obtained in an earlier study. The results accentuate the dominance of the crane operator and general superintendent on the site safety scene and play down the contribution of “classic” site hazards such as power lines. Quantitative measuring of safety, such as reflected in the weights obtained in this study, is important in communicating safety requirements and focusing the limited resources available for safety improvements. These factor weights are also deemed to be a vital component in the development of a comprehensive model that will allow the computation of safety indices for individual construction sites employing tower cranes. It is expected that the methodology can then be adopted for addressing other site safety issues as well.     

纳米金属镍的制备与磁性研究

采用微波polyol还原法成功地制备了单分散5～10 nm镍球颗粒,由高分辨率电子显微镜(HRTEM)观察证实, 5 nm镍的颗粒面间距为0.2033 nm,与文献报道的镍的FCC结构(100)面的0.2034 nm比较吻合[JCPDS: 4-850].通过在不同温度下测量零场冷(ZFC)和场冷(FC,1600 kA·m-1)所获样品的磁滞回线,发现纳米镍从铁磁性过渡到超顺磁性的相变温度Tpt=100 K,在Tpt温度以上,磁滞回线都发生偏置.     

Natural Quorum Sensing Inhibitors – Small Molecules,Big Messages

Due to the increasing emergence of antibiotic resistant bacterial strains within the past few decades, bacterial infections in general – and hospital-borne infections, in particular – have become increasingly difficult to fight. It is therefore crucial to find new strategies to fight pathogenic bacteria. Targeted inhibition of quorum sensing (QS) presents a promising alternative. QS is a cell density-dependent signaling pathway used for intra- and interspecies coordination of gene expression. In many bacteria, pathogenic phenotypes, as well as the expression of virulence factors, are under the control of QS regulons. A closer look at natural quorum sensing inhibitors may be helpful to identify potent compounds that can be used as alternatives to antibiotics. Moreover, it will also provide insight into the interactions between species that compete for the same habitat and resources. This review aims to summarize our current knowledge concerning natural QS inhibitors, as a starting point for the design and synthesis of new therapeutics to treat or prevent bacterial infections.     

Windmill Erection and Maintenance: Challenges for Crane Design

The wide range of crane types and sizes offered by the market expresses the responsiveness of the lifting industry to meet the variety of challenges posed by the built environment. One such emerging set of challenges is the outcome of the growing rate of wind turbine installation. Wind energy is one of the largest alternative energy production methods today, and as the global push for greener energy sources is increasing, so is the number of windmills. This paper addresses the unique lifting challenges posed by windmill installation and maintenance. These challenges have been met by leading crane manufacturers in various ways to produce products not seen before on the construction scene. The paper focuses on two such products representing two different concepts and provides the development and design rational of each. Engineering is impacted by unique height, lifting capacity, site preparation, and environmental requirements. The accelerated rate of global wind energy use, the increasing number, height, and component weight of turbine towers, and the persistent search for new territories for wind farms are likely to further produce more innovative solutions.     

Comparative Analysis of Shoring Towers for High-Clearance Construction

Formwork for cast-in-place concrete in high-clearance construction is commonly based on multitier shoring towers. The market has responded to the demand for shoring towers by offering numerous proprietary models, from which the constructor can choose. Thus, there is a need for comparative data and selection criteria that are comprehensive, objective, uniformly processed, and systematically organized. This paper presents methodology, formatted data, and findings that purport to assist constructors in rationally selecting the appropriate shoring towers for their projects. For the benefit of industry practitioners, the paper offers an overview of tower configuration and classification, a formatted list of selection criteria generated on the basis of input from formwork manufacturers, and interviews with representatives of formwork service companies, examples of comparative data on selected tower models, and quantitative comparisons based on the introduction of normalized parameters and on formwork solutions for typical cases. This information is particularly vital given the high cost of tower-based formwork relative to the overall construction cost of the supported concrete element, while published erection and dismantling work input data are largely still unavailable for most models and heights of shoring towers.     

微波辅助polyol法制备的纳米镍颗粒

采用微波辅助polyol还原法制备了单分散的纳米Ni颗粒。分别用X射线衍射(XRD)和透射电镜(TEM)观测样品的相结构和微观形貌,用振动样品磁强计(VSM)测试Ni颗粒的磁性。XRD显示样品为面心立方结构,TEM观察显示金属镍颗粒的形貌是理想的球型。当把反应温度提高到400℃,并且在实验过程中加入适量的PVP时,发现镍颗粒呈现出一种毛茸茸的多毛形态,这种分散均匀的单一态形貌类似于纳米头发的结构。同时,VSM测试结果表明球型纳米Ni颗粒具有典型的铁磁性。