Clustering high dimensional data: A graph-based relaxed optimization approach

There is no doubt that clustering is one of the most studied data mining tasks. Nevertheless, it remains a challenging problem to solve despite the many proposed clustering approaches. Graph-based approaches solve the clustering task as a global optimization problem, while many other works are based on local methods. In this paper, we propose a novel graph-based algorithm “GBR” that relaxes some well-defined method even as improving the accuracy whilst keeping it simple. The primary motivation of our relaxation of the objective is to allow the reformulated objective to find well distributed cluster indicators for complicated data instances. This relaxation results in an analytical solution that avoids the approximated iterative methods that have been adopted in many other graph-based approaches. The experiments on synthetic and real data sets show that our relaxation accomplishes excellent clustering results. Our key contributions are: (1) we provide an analytical solution to solve the global clustering task as opposed to approximated iterative approaches; (2) a very simple implementation using existing optimization packages; (3) an algorithm with relatively less computation time over the number of data instances to cluster than other well defined methods in the literature.     

Supporting Urban Search and Rescue with digital assessments of structures and requests of response resources

First responders, including structural engineers and firefighters, inspect buildings and identify the structural integrity of buildings within a disaster affected area. The performance of their inspection and dissemination of the assessment information are critical to Urban Search and Rescue (US&R) operations. This paper presents an innovative approach for structural assessment and resource requests through an application – Supporting Urban Preparedness and Emergency Response using Mobile Ad hoc Network (SUPER-MAN). The goal of this research is to address challenges encountered in the current practice for structural engineers and first responders to inspect and disseminate building damage assessments and resource requests more efficiently to support US&R. The SUPER-MAN system is equipped with Radio Frequency Identification (RFID) tags, as the storage device of assessment information on the disaster site, and a Mobile Ad hoc Network (MANET) with a Dynamic Source Routing (DSR) implementation for communication. SUPER-MAN strengthens responders’ situational awareness, reduces confusion of inconsistent assessment formats, and automates information dissemination and editing. As a result, lifesaving operations are adequately prioritized, risk of first responders are minimized, and requests of response resources are facilitated. Results obtained from field trials carried out at the Illinois Fire Service Institute with a simulated disaster scenario and computer simulations of the MANET are presented to highlight the benefits provided by SUPER-MAN.     

Evaluation of image-based modeling and laser scanning accuracy for emerging automated performance monitoring techniques

Accurate and rapid assessment of the as-built status on any construction site provides the opportunity to understand the current performance of a project easily and quickly. Rapid project assessment further identifies discrepancies between the as-built and as-planned progress, and facilitates decision making on the necessary remedial actions. Currently, manual visual observations and surveying are the most dominant data capturing techniques but they are time-consuming, error-prone, and infrequent, making quick and reliable decision-making difficult. Therefore, research on new approaches that allow automatic recognition of as-built performance and visualization of construction progress is essential. This paper presents and compares two methods for obtaining point cloud models for detection and visualization of as-built status for construction projects: (1) A new method of automated image-based reconstruction and modeling of the as-built project status using unordered daily construction photo collections through analysis of Structure from Motion (SfM); (2) 3D laser scanning and analysis of the as-built dense point cloud models. These approaches provide robust means for recognition of progress, productivity, and quality on a construction site. In this paper, an overview of the newly developed automated image-based reconstruction approach and exclusive features which distinct it from other image-based or conventional photogrammetric techniques is presented. Subsequently the terrestrial laser scanning approach carried out for reconstruction and comparison of as-built scenes is presented. Finally the accuracy and usability of both of these techniques for metric reconstruction, automated production of point cloud models, 3D CAD shape modeling, and as-built visualizations is evaluated and compared on eight different case studies. It is shown that for precise defect detection or alignment tasks, image-based point cloud models may not be as accurate and dense as laser scanners' point cloud models. Nonetheless image-based point cloud models provide an opportunity to extract as-built semantic information (i.e., progress, productivity, quality and safety) through the content of the images, are easy to use, and do not need add burden on the project management teams by requiring expertise for data collection or analysis. Finally image-based reconstruction automatically provides photo alignment with point cloud models and enables image-based renderings which can remarkably impact automated performance monitoring and as-built visualizations.     

Study of Real Options with Exogenous Competitive Entry to Analyze Dispute Resolution Ladder Investments in Architecture, Engineering, and Construction Projects

Architecture, engineering, and construction industry participants often find it pragmatic to implement a project-specific dispute resolution ladder (DRL) as a managerial tool to assist in the prompt resolution of claims and change orders (CCOs) that might arise during the project construction phase. This project-specific DRL consists of a single or multiple alternative dispute resolution (ADR) techniques that require capital expenditures to cover the expenses incurred by the owner’s/contractor’s employees and third-party neutrals. If a project-specific DRL is properly chosen, then the capital expenditures are outweighed by the expected benefits from the DRL implementation; namely, prompt resolution of the CCOs without incurring excessive cost overruns on an already financially stressed project budget, as well as avoiding the escalation of the claims to a dispute that requires long protracted litigation for final settlement. Typically, the decision as to which ADR techniques to include in the project-specific DRL is undertaken during the project planning phase prior to the actual occurrence of the CCOs. In this case, the project owner decide to invest in a DRL in exchange for the expected savings in the project. This decision regarding the project-specific DRL is usually done based on the experience of the project parties with the ADR techniques. However, such a decision needs to be guided by a financial tool that allows the project owner to evaluate alternative DRLs and choose the most economically feasible alternative based on the project and ADR characteristics. In this paper, a financial model is developed to evaluate DRL implementations in construction projects by drawing analogies from real option theory with exogenous competitive entry. More specifically, the occurrence of a given CCO will result in a reduction in the value of expected savings in the project due to DRL implementation. This is similar to the reduction in the gross value of a capital investment project in a commercial property due to competitive entry by another similar commercial property developer in the market. At the same time, the CCO resolution due to an effective DRL implementation will allow project owner to recover part of the losses in the expected savings in the project due to the DRL implementation. The model presented in this paper takes into account the characteristics of the various ADR techniques included in the project-specific DRL, and the characteristics of the CCOs occurring during the construction phase of the project. A case study of a real construction project is used to illustrate the practical implementation of the model. The results indicate that for this case project and from a financial point of view, the investment in the chosen project-specific DRL was not worthwhile because of the high uncertainty in the project, and the low effectiveness of the selected DRL. These conditions did not provide the owner with the anticipated advantage of the DRL implementation in reducing the value of the CCOs occurring in the project. At the same time the cost of the DRL implementation exceeded the actual savings attained in the project.     

Hybrid Model Incorporating Real Options with Process Centric and System Dynamics Modeling to Assess Value of Investments in Alternative Dispute Resolution Techniques

Project-specific dispute resolution ladders (DRLs) are typically implemented in construction projects to resolve issues arising between the project participants. The DRL typically consists of single or multiple alternative dispute resolution (ADR) techniques to address construction issues at the three levels of escalation: conflicts; disputes; and claims. However, a DRL requires significant investments to cover the direct costs incurred in-house by the project participants or, externally, if construction specialists and lawyers are recruited to assist in the resolution. Thus, the benefits of the DRL implementation in a construction project must outweigh its costs for the implementation to be worthwhile. This paper presents a methodology to study the effect of different resolution strategies on the value of the investment in a DRL using option/real option theories from financial engineering, process centric modeling, and system dynamics methodology. Of particular interest in this paper is the integration of these research methodologies into a computer model to support the evaluation of the DRL investment in a particular construction project by taking into account the characteristics of (1) the project and (2) the different ADR techniques chosen for the DRL implementation. Finally, an example is presented to illustrate the application of the computer model in a real construction project. The results of the simulation serve two main purposes. First, the results of the simulation are used to verify the intended model behavior in terms of proper integration of the three methodologies (i.e., real options, process centric, and system dynamics) in one computer system. Second, the model application to a real construction project using actual project data illustrates the potential of the model in providing the project participants with information related to the expected number of claims and change orders resolved at each level of the DRL, the change in the expected savings during the construction phase, and finally the value of the investment from the perspective of the project owner.     

Assessment of the sulfide corrosion fatigue strength for a multi-pass welded A106 Gr B steel pipe below the low SSCC limit

In the area of heavy construction, welding processes are vital in the production and maintenance of pipelines and power plants. Welding processes happen to produce residual stresses and change the metal structure as a result of the large nonlinear thermal loading that is created by a moving heat source. The fusion welding process generates formidable welding residual stresses and metallurgical change, which increase the crack driving force and reduce the resistance to the brittle fracture as well as the environmental fracture. This is a serious problem with many alloys as well as the A106 Gr B steel pipe. This pipe that is used in petrochemical and heavy chemical plants either degrades due to corrosive environments, e.g., chlorides and sulfides, and/or become damaged during service due to the various corrosion damage mechanisms. Thus, in this study, after numerically and experimentally analyzing the welding residual stress of a multi-pass welded A106 Gr B steel pipe, the sulfide stress corrosion cracking (SSCC) characteristics were assessed in a 3.5 wt.% NaCl solution that was saturated with H₂S gas at room temperature on the basis of NACE TM 0177-90. The specimens used are of two kinds: un-notched and notched. Then, the sulfide corrosion fatigue (SCF) strength for the un-notched specimen was assessed below the low SSCC limit that was previously obtained from the SSCC tests for the notched specimen. From the results, in terms of the SSCC and SCF, all the specimens failed at the heat-affected zone, where a high welding residual stress is distributed. It was found that the low SSCC limit of un-notched specimens (σ_{SSCCun-notched}) was 46% (230 MPa) of the ultimate tensile strength (σ_U=502 MPa) of a multi-pass welded A106 Gr B steel pipe, and the notched specimens (σ_SSCCnotched) had 40% (200 MPa) of the ultimate tensile strength. Thus, it was determined that σ_{SSCCun-notched} was 13% lower than σ_SSCCnotched. Further, the sulfide corrosion fatigue limit (σ_{SCFun-notched}) was 32% (160 MPa) of the ultimate tensile strength of welded specimens. This σ_{SCF un-notched} was 20% lower than σ_SSCCnotched.     

高寒草原地区安格斯和西门塔尔母牛血液及肌内脂肪酸组成特性

随机采集48 月龄安格斯和西门塔尔母牛各37 头血液样品以及用于肉质分析的各5 头母牛背最长肌肉样。样品经过前处理和甲酯化后,利用气相色谱-质谱联用仪测定脂肪酸组成和含量,对血液和肌内脂肪酸组成特性进行分析。结果表明：安格斯和西门塔尔母牛血液和肌内脂肪中均测得36 种脂肪酸,样品中均含有51%以上的高含量饱和脂肪酸（saturated fatty acids,SFA）,且具有以棕榈酸和硬脂酸为主的组成特点,二者总含量分别约占血液和肌内脂肪SFA的92%和89%;不饱和脂肪酸（unsaturated fatty acids,UFA）中油酸相对含量最高,其次为亚油酸;血液和肌内脂肪的油酸含量均约占单不饱和脂肪酸总量的87%,UFA中各主要脂肪酸组成在血液中有显著性差异,而在肌内脂肪中无显著性差异;血液和肌内脂肪中n-6/n-3 PUFA均符合联合国粮农组织（United Nations Food Agriculture Organization,FAO）推荐比例（5～10）,血液中P/S高于世界卫生组织（World Health Organization,WHO）推荐标准（≥0.4）。综上所述,高寒草原饲养的纯种安格斯和西门塔尔母牛血液和肌内脂肪酸组成特性相似,UFA符合FAO和WHO理想比值及推荐标准,具有较高的营养价值。     

Microstructure of indium tin oxide films produced by the D.C. sputtering technique

The effect of grain growth in indium tin oxide films deposited using the d.c. sputtering tecjnique was studied as a function of annealing temperature. The results were correlated with the observed electrical properties.     

Novel Methodology for Designing Frequency Selective Surfaces with Miniaturized Cells

Miniaturization of Frequency Selective Surface’s ( FSS’s) size is significant for its application in the limited space. In this paper, a novel methodology for designing low-profile FSS is discussed, and a corresponding multi-layer structure with lumped elements for band-pass response is presented. Based on the equivalent circuit theory,the inductive designed center layer is firstly discussed. Then different numbers of additional capacitive designed layers are added and their performances are presented. Finally,the lumped elements are added both between adjacent layers and between adjacent cells of the additional layers so that the miniaturization performance can be further improved. The simulations for each structure in waves of different polarizations and incident angles are conducted,and the results are presented,which demonstrate the claimed characteristics of the proposed structure.