Building Information Modeling in Architecture, Engineering, and Construction: Emerging Research Directions and Trends

Currently, the architecture, engineering, and construction industry is facing enormous technological and institutional changes and challenges including the proliferation of information technology and appropriate application of sustainable practices. The 21st century engineer and architect must be able to deal with a rapid pace of technological change, a highly interconnected world, and complex problems that require multidisciplinary solutions. This paper focuses on research directions and trends around building information modeling (BIM) through interdisciplinary endeavors: how BIM research topics could be explored; their relevancy; and their potential future impact. It identifies BIM research topics that are considered to be important to a wide range of practitioners and future practitioners, both architecture and engineering students. It also assesses the relevance of current research projects to the industry and categorizes future BIM research topics. It aims to formulate research ideas and methodologies to pursue them and to explore how an industry/academic partnership for exploring exciting research opportunities could be established.     

Computational Modeling of Microstructure Evolution in Solidification of Aluminum Alloys

In this article, a front tracking (FT) model and a modified cellular automaton (MCA) model are presented and their capabilities in modeling the microstructure evolution during solidification of aluminum alloys are demonstrated. The FT model is first validated by comparison with the predictions of the Lipton–Glicksman–Kurz (LGK) model. Calculations of the steady-state dendritic tip growth velocity and equilibrium liquid composition as a function of melt undercooling for an Al-4 wt pct Cu alloy exhibit good agreement between the FT simulations and the LGK predictions. The FT model is also used to simulate the secondary dendrite arm spacing as a function of local solidification time. The simulated results agree well with the experimental data. The MCA model is applied to simulate dendritic and nondendritic microstructure evolution in semisolid processing of an Al-Si alloy. The effect of fluid flow on dendritic growth is also examined. The solute profiles in equiaxed dendritic solidification of a ternary aluminum alloy are simulated as a function of cooling rate and compared with the prediction of the Scheil model. The MCA model is extended to the multiphase system for the simulation of eutectic solidification. A particular emphasis is made on the quantitative aspects of simulations. This article is based on a presentation made in the symposium ”Simulation of Aluminum Shape Casting Processing: From Design to Mechanical Properties,” which occurred March 12–16, 2006, during the TMS Spring Meeting in San Antonio, Texas, under the auspices of the Computational Materials Science and Engineering Committee, the Process Modeling, Analysis and Control Committee, the Solidification Committee, the Mechanical Behavior of Materials Committee, and the Light Metal Division/Aluminum Committee.     

Research on Gossip: Taxonomy, Methods, and Future Directions.

A half century of gossip research from multiple disciplines is reviewed. Discussed are definitions of the construct: social, evolutionary, and personal functions of the practice; and data collection methods. Though people engage in the practice frequently, there has been relatively little psychological research on gossip. The layperson's understanding of the term is included in, but insufficient to encompass, definitions used by researchers. Most data are ethnographic and discursive, and few parametric data exist. The area could benefit from better experimental methods and instruments. Neurobiological and social network analysis methods are promising foundations for further study. There are real-world implications for understanding gossip. Strengthening gossip theory and research methods will beneficially inform the way we view the practice in context. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Phase-Field Modeling of Microstructure Evolution in the Presence of Bubble During Solidification

Simulation of the solid–liquid–gas interaction during solidification is challenging due to the presence of complex phase interfaces, bubble deformation, and high liquid/gas density ratio. In this work, a hybrid phase-field lattice-Boltzmann (PFLB) approach, together with a parallel and adaptive-mesh-refinement (Para-AMR) algorithm, is developed to model interactions between the gas bubble and solid growth front during solidification. The solid growth and bubble evolution are solved by the phase-field method. Both melt flow and bubble movement are determined by a kinetic-based lattice-Boltzmann model. Bubble dynamics during alloy solidification is modeled and compared with experiments, and a good agreement is achieved for various solid/liquid interfaces including planar, cellular, and dendritic interfaces. Results show that the effect of the bubble on solid array is dependent on the solid/liquid interface morphology, bubble size, and relative position between the bubble center and dendritic tip. Two interaction mechanisms, including engulfment and entrapment, are compared, and the difference is caused mainly by the redistribution of solute. The interaction mechanism between the rising multibubbles with large deformation and the dendritic array is also discussed.     

Mathematical Modeling of the Solidification Structure Evolution in the Presence of Ultrasonic Stirring

Ultrasonic treatment (UST) was studied in this work to improve the quality of the cast ingots as well as to control the solidification structure evolution. Ultrasonically induced cavitation consists of the formation of small cavities (bubbles) in the molten metal followed by their growth, pulsation, and collapse. These cavities are created by the tensile stresses that are produced by acoustic waves in the rarefaction phase. The pressure for nucleation of the bubbles (e.g., cavitation threshold pressure) may decrease with increasing the amount of dissolved gases and especially with the amount of inclusions in the melt. Modeling and simulation of casting solidification of alloys with UST requires complex multiscale computations, from computational fluid dynamics (CFD) macroscopic modeling through mesoscopic to microscopic modeling, as well as strategies to link various length-scales emerged in modeling of microstructural evolution. The developed UST modeling approach is based on the numerical solution of the Lilley model (that is founded on Lighthills’s acoustic analogy), fluid flow, heat transfer equations, and mesoscopic modeling of the grain structure. The CFD analysis tool is capable of modeling acoustic streaming and ultrasonic cavitation. It is used in this work to study ingot solidification under the presence of ultrasound. The UST model was applied to low-temperature alloys including Al- and Mg-based alloys. Although the predicted ultrasonic cavitation region is relatively small, the acoustic streaming is strong and, thus, the created/survived bubbles/nuclei are transported into the bulk liquid quickly. The predicted grain size under UST condition is at least one order of magnitude lower than that without UST.     

Evapotranspiration: Concepts and Future Trends

Past research on evapotranspiration has provided sound theoretical knowledge and practical applications that have been validated through field measurements. Many different approaches have been used; however, when primary concepts and standard definitions are accepted, it is possible to find reasonable agreement among methods. This paper reviews such approaches, from Penman to Penman-Monteith. The standard concepts of potential evaporation (EP) and equilibrium evaporation (Ee), and the introduction of the climatic resistance (re), provide a better understanding of the role of the climate together with surface and aerodynamic resistances (rs and ra). Therefore, the concept of reference evapotranspiration (ETo), particularly the new one adopted by the Food and Agricultural Organization of the United Nations, can be better understood, as well as its limitations. Crop evapotranspiration (ETc) is related to both ETo and Ee. Crop coefficients (Kc) can be shown to have two components, αo and αc, with Kc = αoαc. The αo is a function of the climatic resistance and of the aerodynamic resistances of the crop and of the reference crop. The αc is a function of both surface and aerodynamic resistances of the crop and of the reference crop. From this analysis some ideas on future developments result that are directed toward providing compatibility between the one- and two-step calculation of ETc.     

Materials Handling System Simulation in Precast Viaduct Construction: Modeling, Analysis, and Implementation

The interactive, complicated system environment of a construction site renders conventional site layout planning and scheduling techniques to be inadequate in coping with materials handling system design in construction. In this paper, we present a university-industry joint endeavor for improving the effectiveness of the materials handling system on a precast viaduct construction project in Hong Kong by implementing the simplified discrete-event simulation approach (SDESA) along with its computer platform resulting from recent research. How to apply the simulation methodology of SDESA is elaborated step by step. Particular emphasis is placed on procedures of establishing a simulation model, validation of the simulation model, design of simulation experiments, and analysis of simulation results. With process flowchart, site layout plan, and process animation produced in a view-centric simulation environment, it is straightforward to establish, validate, and communicate the operations simulation. The research team convinced the project director, as well as field managers, of the functionality and effectiveness of operations simulation. The knowledge derived from simulation added to experiences of site managers in materials handling system design. With the aid of simulation, even junior engineers would be capable and confident to draw up an actionable construction plan that would lead to enhancement of cost effectiveness and productivity in the field.     

Multiphase Solidification Modeling of Solidification Structure Evolution and Macrosegregation of Round Bloom Continuous Casting Process with Mold Electromagnetic Stirring and Final Electromagnetic Stirring

Based on Eulerian–Eulerian method, a 3D/2D multiphase solidification model, which takes into consideration the heat transfer and fluid flow with grains nucleation and crystal growth, is developed to predict the macrostructure evolution and macrosegregation in continuously cast round bloom. The results show that the mold electromagnetic stirring (M-EMS) can accelerate superheat dissipation and promote grain nucleation, but the horizontal swirl induced by M-EMS has a strong washing effect on the solidification front and leads to subsurface negative segregation. When the M-EMS current intensity increases from 200 to 300 A, the subsurface negative segregation ratio decreases from 0.935 to 0.875. The final electromagnetic stirring (F-EMS) not only improves the center segregation, but also leads to the formation of negative segregation zone near the round bloom center due to the enhancement of solute washing induced by F-EMS. As the F-EMS current intensity increases from 150 to 300 A, the center segregation ratio decreases from 1.148 to 1.075, and the negative segregation ratio near the strand center decreases from 0.985 to 0.977. Another phenomenon is found that the nucleation of equiaxed grain ahead of columnar tips restrains the solute diffusion and leads to a local macrosegregation in columnar-to-equiaxed transition zone.     

Heat Flow and Solidification Modeling of Industrial Scale,Ingot Casting Operation

A model, based on the concept of effective thermal conductivity, was developed to study thermal fields and the resultant solidification behavior of large, round, industrial size ingots. In this, flow and turbulence phenomena during mold filling as well as subsequent solidification were not modeled explicitly but their influence was accounted for by artificially raising the thermal conductivity of solidifying steel. Thus, a conduction like equation embodying a conjugate approach was applied to simultaneously predict the evolution of temperature fields in the mold as well as in the solidifying ingot following teeming. Prior to comparing model predictions against industrial scale measurements, sensitivity of calculations to grid size, time step height, convergence criterion etc. were rigorously assessed. Similarly, modeling of interfacial resistance, chemical reactions and heat effects in the hot top as well as their influence on predicted results were evaluated computationally. Embodying mixed thermal boundary conditions (free convection + radiation) at the mold wall, temperature fields during solidification of two different industrial large ingots were predicted numerically. Parallely, mold wall temperature was monitored as a function of time and surface temperature of ingot was measured at the instant of mold stripping using hand held, radiation pyrometers. Incorporating relevant operating conditions (viz., mold dimensions and size, ingot and hot top dimensions and material, initial mold and liquid temperature etc.) into the calculation scheme, predictions were made via a computational procedure developed in-house and results thus obtained were compared against equivalent industrial scale measurements. Very reasonable agreement between the two was demonstrated.     

Multi-Phase-Field Modeling of Solidification in Technical Steel Grades

Following a short introduction into multi-phase-field modeling, a short review of applications of the multi-phase-field concept to modeling of solidification of steels is given. Starting from simulations of directional dendritic solidification and peritectic reaction in a simple binary Fe?CC system, further extensions to more complex alloys involving e.g. the formation interdendritic MnS or of TiN and to more complex processes are depicted. As a recent example, effects of microstructure features on hot cracking susceptibility in commercial HSLA steel grades are discussed on the basis of multi-phase field simulations. Preliminary results indicate a pronounced effect of precipitates on hot cracking susceptibility.     

Psychological Treatment of Musical Performance Anxiety: Current Status and Future Directions.

A comprehensive review of research evaluating psychological treatments of musical performance anxiety is provided. Studies were evaluated against key methodological criteria for psychotherapy outcome research. Available literature points to the utility of exposure and cognitive therapies, although there is no clear-cut evidence suggesting the superiority of one approach or benefits of combining the two. Past research is characterized by recurring methodological limitations, particularly overreliance on self-report outcome measures. Future investigations should consider screening out individuals who do not evidence marked dysfunction and whose anxiety results from weak technical ability, as well as including treatment manuals, multiple therapists, multichannel outcome measures, and follow-up data. Clinicians working with musicians experiencing performance anxiety may wish to incorporate exposure and cognitive restructuring in treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ice Adhesion to Locks and Dams: Past Work; Future Directions?

Adhesion of ice to surfaces creates problems for many industries, including aviation, hydropower, telecommunications, navigation, electrical distribution, and all forms of transportation. Specific problems at locks and dams include ice buildup on lock walls and miter gates, and spillway gate freeze up, preventing opening on short notice. At present, ice removal techniques are both costly and time-consuming. In an effort to reduce the cost, time, and physical labor associated with ice removal, much research on ice adhesion has been done. This work ranges from theoretical studies to microscopic investigations and full-scale field tests. The main focus of all of these studies is how to lower ice’s adhesive strength, thus easing ice removal. Three principal methods to lower ice’s adhesive strength have been pursued—electrical, chemical, and mechanical. Of the three methods, the mechanical removal of ice has received the least amount of attention. Three approaches have been taken with regard to electrical methods. They are using heaters, creating an electrical pulse that mechanically breaks the ice, and applying a direct current bias to change the ice’s adhesion. The search for a low adhesive coating or material has by far received the most attention of any method pursued for lowering ice’s adhesive strength. A class of chemicals containing polysiloxanes has shown promise in providing a low adhesion surface. Based on this review, we recommend that an electroexpulsion method developed for the space shuttle and a newly formulated polysiloxane be tested as to their feasibility in the lock and dam environment.     

The Scope and Impact of Perinatal Loss: Current Status and Future Directions.

The loss of an expected child can be devastating and traumatizing for parents, placing them at risk for postloss mental health complications, such as complicated or traumatic grief. The authors review the psychological and social impacts of perinatal loss and describe the standard care provided in the hospital. The authors review studies that examine the efficacy of standard care and highlight the need for empirical evidence confirming the efficacy of these current interventions. The authors provide recommendations for health care professionals in contact with the perinatally bereaved and suggest areas for future research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Modeling of Electromagnetic,Temperature,and Velocity Fields During Solidification in an Electromagnetically Stirred Melt

This paper describes a comprehensive model for predicting the evolution of the velocity and temperature fields in electromagnetically-driven flows during solidification.The electromagnetic field was formulated using the mutual inductance method,which accounts for the metal,chill blocks,and magnetic shields.The model solves the heat transfer equation throughout the system,as well as the fluid flow equations in the liquid and mushy regions.A two-zone model for the mushy region that accounts for dampening of momentum by the turbulent field has been developed.The turbulence in the molten region was determined using the k-s model.Calculations were performed for unidirectional solidification in a bottom chill mold placed in a stationary magnetic field.Computed results show that the flow field at the beginning of solidification shows typical four recirculating loops,and later evolves to two recirculating loops as solidification progresses.The magnitude of the velocity in the bulk liquid was found to decrease as solidification progresses.     

Modeling Natural Convection in Copper Electrorefining: Describing Turbulence Behavior for Industrial-Sized Systems

A computational fluid dynamics (CFD) model of copper electrorefining is discussed, where natural convection flow is driven by buoyancy forces caused by gradients in copper concentration at the electrodes. We provide experimental validation of the CFD model for several cases varying in size from a small laboratory scale to large industrial scale, including one that has not been compared with a CFD model. Previously, the large-scale systems have been thought to be turbulent by some workers and modeled accordingly with k-ε type turbulence models, but others have not considered turbulence effects in their modeling. We find that the turbulence model does not predict turbulence exists; however, we analyze carefully the fluctuation statistics predicted for a transient model, finding that most cases considered do exhibit a type of turbulence, an instability related to the interaction between velocity and copper concentration fields. We provide a comparison of the extent of turbulence for various electrode heights, and gap widths, and we emphasize industrial-sized electrorefining cells.