Building Information Modeling Approach Research Articles

Intelligent optimal design of floor tiles: A goal-oriented approach based on BIM and parametric design platform

Floor tile is an essential building material, which is extensively used in the Architectural, Engineering and Construction (AEC) industry. Current existing design-aid approaches for floor tiles are based on simulating the manual design, lacking the attention to proactive planning on cut tiles. Therefore, the existing design-aid tools cannot enable users to generate accurate and comprehensive design results to reduce material and labor waste. Building information modeling (BIM) and parametric design (PD) approaches show considerable potential in optimizing building materials’ design. This research proposed a workflow based on the BIM and PD approaches to generate and optimize floor tiles’ layout design intelligently. The workflow formalizes the trades know-how cutting and planning rules of floor tiles, including the proactive planning of cut tiles, into a design algorithm to automatically generate the floor tiles planning and while reducing material waste. An evolutionary algorithm (EA) is then integrated with the workflow to conduct goal-oriented optimization for the generated planning. Moreover, due to the formalized design algorithm considering the cut tiles planning, the workflow expects to output accurate and comprehensive results, including uncut and cut tiles’ graphical and numerical results. We developed a prototype system in Rhino (a BIM platform) and Grasshopper (a PD platform) to verify the feasibility of the proposed workflow. The results show that the prototype system effectively generates and optimizes floor tiles’ layout design (using 19.1s–116.4s) and provides accurate and comprehensive coordinate points for positioning the cutting and laying of uncut and cut tiles. Compared with the industry benchmark (i.e., 10%–15%), the material waste rates of the generated layouts have been significantly reduced, which are 3.43%–5.50%. The outcomes are summarized to provide deeper insight for improving floor tile prefabrication, robot construction, and transportation, as well as the promotion of the sustainable development of the AEC industry.

A parametric BIM approach to foster bridge project design and analysis

Advancements in technology have contributed significantly to building information modeling (BIM)-based construction project management. However, the BIM approach was developed mainly around building construction projects and few efforts have been devoted to projects related to infrastructures such as bridges. For such projects, there are often significant geometric and semantic variations between structures, making it difficult to use existing BIM data schemas. Recent works indicate that parametric modeling could represent a solution providing greater design efficiency and interoperability, but the literature on the subject remains extremely sparse. The objective of the present study is to develop a parametric file that is able to generate all types of bridges from a single parametric file. The file developed uses a parametric algorithm for modeling bridge elements in a design software application and for generation and analysis of the model in a structural analysis software application.

Procedural Modeling-Based BIM Approach for Railway Design

Building information modeling (BIM) is a powerful methodological approach for designers that has revolutionized the field of architecture and construction for some years now, minimizing errors and making the entire design, construction, and management process more efficient. The first results have been so encouraging that many countries, from Europe to the United States to Asian countries, have adopted specific regulations to promote its development and use. BIM models are based on the Industry Foundation Classes (IFC) standard, i.e., an object-based file format with a data model developed by building SMART to facilitate interoperability. Objects are characterized by properties, such as geometry, material, cost, and all related construction process information, such as scheduling or the maintenance process. The 3D modeling of these objects geometric information is parametric, in order to make the design more flexible. This research work offers an insight into the possibilities offered by different BIM-based tools for parametric modeling applied in the railway sector whereby an example of a railway section model is presented. Indeed, the focus will be on the creation of parametric objects representing railway components, as existing BIM object libraries lack them in the IFC2 × 3 standard format.

Reality Capture of Buildings Using 3D Laser Scanners

The urgent need to improve performance in the construction industry has led to the adoption of many innovative technologies. 3D laser scanners are amongst the leading technologies being used to capture and process assets or construction project data for use in various applications. Due to its nascent nature, many questions are still unanswered about 3D laser scanning, which in turn contribute to the slow adaptation of the technology. Some of these include the role of 3D laser scanners in capturing and processing raw construction project data. How accurate are the 3D laser scanner or point cloud data? How does laser scanning fit with other wider emerging technologies such as building information modeling (BIM)? This study adopts a proof-of-concept approach, which in addition to answering the aforementioned questions, illustrates the application of the technology in practice. The study finds that the quality of the data, commonly referred to as point cloud data, is still a major issue as it depends on the distance between the target object and 3D laser scanner’s station. Additionally, the quality of the data is still very dependent on data file sizes and the computational power of the processing machine. Lastly, the connection between laser scanning and BIM approaches is still weak as what can be done with a point cloud data model in a BIM environment is still very limited. The aforementioned findings reinforce existing views on the use of 3D laser scanners in capturing and processing construction project data.

Green BIM potential in assessing the sustainable design quality of low-income housing: A review

This paper intended to investigate the potential use of Building Information Modeling (BIM) as an assessment tool that can evaluate and support optimization of sustainable design quality, especially for low-income housing or “Masyarakat Berpenghasilan Rendah” (MBR) in Indonesia. The consideration of sustainability aspects in the preliminary design phase is no longer a choice but a need for every stakeholder involved in the Architecture, Engineering, and Construction (AEC) industry. BIM here was developed to be the effective technology that supports all stakeholders in integrating the needs of sustainable building design through sustainable workflow which is also known as “Green BIM”. The first phase of this study is conducting a critical review of integration between BIM and Green Building Rating System for Home, including LEED, BREEAM, GBI, Green Mark, and GREENSHIP. Then it is followed by reviewing BIM implementation in the housing sector based on case studies in several countries. The findings revealed that there is a potential use of BIM for small-scale project especially to support the sustainability of MBR in Indonesia. Even so, there are also challenges to be considered, including financial support and incentives from the government in the effort of implementing this Green BIM approach.

BIM Approach to Modeling a Sports Pavilion for University Use

New developments in software projects for the construction sector are a technological revolution and provide new methods of infrastructure design and modeling, highlighting the Building Information Modeling (BIM). BIM is a technology and methodology used in the most developed countries and little by little this technology is being implemented in other countries where its use is increasing. This new work methodology makes it easier to manage and plan new projects, saving time and minimizing costs. The advantages of using BIM stand out in large projects thanks to the better handling of large volumes of information. This article will address, with the example of using BIM technology, the design project of a fictitious university sports pavilion located in Seville (Spain). Using the BIM Edificius® software, the 3D modeling of this building will be carried out in order to calculate and design the building’s facilities with CYPECAD MEP® software, making use of the IFC (Industry Foundation Classes) format to exchange the building design between both programs.

A Building Information Modeling Approach to Integrate Geomatic Data for the Documentation and Preservation of Cultural Heritage

Non-destructive testing (NDT) techniques play an important role in the characterization and diagnosis of historic buildings, keeping in mind their conservation and possible rehabilitation. This paper presents a new approach that merges building information modeling (BIM) with environment geospatial data obtained by several non-destructive techniques, namely terrestrial laser scanning, ground-penetrating radar, infrared thermography, and the automatic classification of pathologies based on RGB (red, green, blue) imaging acquired with an unmanned aircraft system (UAS). This approach was applied to the inspection of the Monastery of Batalha in Leiria, Portugal, a UNESCO World Heritage Site. To assess the capabilities of each technique, different parts of the monastery were examined, namely (i) part of its west façade, including a few protruding buttresses, and (ii) the masonry vaults of the Church (nave, right-hand aisle, and transept) and the Founder’s Chapel. After describing the employed techniques, a discussion of the optimization, treatment and integration of the acquired data through the BIM approach is presented. This work intends to contribute to the application of BIM in the field of cultural heritage, aiming at its future use in different activities such as facility management, support in the restoration and rehabilitation process, and research.

I-BIM based approach for geotechnical and numerical modelling of a conventional tunnel excavation

Very recently the Building Information Modeling (BIM) design approach has landed in the infrastructure field, giving life to the I-BIM, the BIM for the infrastructures, including geotechnical underground works likes tunnels. In this framework, the present paper shows an application in the field of geotechnical engineering of the BIM based design approach to the case of an underground line. It is a tunnel excavated by means of traditional method, currently under construction. The project defines, in a central BIM model, a detailed tunnel structure model integrated with geological-geotechnical information for the definition of the subsoil 3D model. Once the BIM model of the tunnel stretch under study was completely defined, it was imported into a finite element (FE) model to perform deformation analyses. Thus, BIM-to-FEM-to-BIM interoperability was exploited in order to verify the maturity level of the BIM approach in the field of application for geotechnical infrastructures. Finally, the BIM fourth dimension (4D) was also implemented in the central model for the time management of the tunnel excavation process, synchronized with the numerical model. The BIM based procedure proposed in the present work can be considered as a case study in the technical literature of I-BIM for tunnels, putting in evidence limitations and advantages: i) a high level of BIM maturity was not yet achieved in the infrastructures field; ii) the BIM-to-FEM interoperability seems to be not fully effective and many operations still require the manual intervention; iii) the FEM-to-BIM interoperability brings back all geotechnical choices and hypothesis to the central BIM model, linking the models into a continuously interoperable circuit; iv) an important part of the design of civil infrastructures consists of addressing geotechnical aspects, hence the inclusion of ground conditions and geotechnical data into the BIM model can improve the quality and the usefulness of the model, not only during the design phase but also, and in particular, during the construction and the lifecycle management of the infrastructure, as a support to decision making process especially in urban context.

Planning the maintenance of green building materials for sustainable development: a building information modelling approach

PurposeMost green building (GB) materials, which are used widely in the construction sector in Malaysia, perform poorly in terms of energy efficiency and sustainability. Nevertheless, during maintenance planning of these materials, the focus is often directed towards comfort and design instead. However, as GB material construction projects grow in scale and complexity, interconnections between the activities and processes can be noticed during problematic planning performance management to monitor the GB material components for corrective and preventive maintenance actions.Design/methodology/approachThe concept of GB material maintenance planning for sustainable development and the main features of information and communication technology tools and techniques are based on analysis of literature reviews of GB material scenarios.FindingsThe results show how decision-making support in maintenance planning can be unsuccessful and how planning decisions can frame the content of an integrated system to analyse information and reduce risks of GB material failure.Originality/valueThe paper concludes that implementing a research framework for developing such a system can help improve the sustainable performance of maintenance planning of GB material economic, social and environmental issues.

Digital Transition and Waste Management in Architecture, Engineering, Construction, and Operations Industry

The research aims at analyzing the integration of Waste Management (WM) strategies and Information management in the construction procurement process. The application of Building information modelling (BIM) methodologies for a Most Economically Advantageous Tender could address the digital transition in order to adopt environmentally sustainable practices. Despite the wide regulation regarding waste minimization, an overview of which is provided, AECO is still one of the most polluting industrialized sector. Drivers and barriers to the method, and a literature review are provided: BIM approaches to enable WM practices have been analyzed from the designer and constructor’s point of view, but few studies investigated the role of the Client, in particular the Public Client. The goal of the study was to evaluate the efficiency of Most Economically Advantageous Tender and a BIM methodology to promote WM strategies during the tender phase. Design Build (DB) and Design Bid Build (DBB) procurement models are tested through three case studies of Italian schools' calls for proposals: the BIM model enabled to verify the bids in terms of WM strategies implementation. Blockchain and Smart contract future applications are also investigated in order to ensure transparency of the whole process. The Public Client could trigger a change in the construction sector regarding the integration of WM practices, as a central and active actor of the construction process, through the application of Green Public Procurement and BIM methodologies.

An historical building information modelling approach for the preventive conservation of historical constructions: Application to the Historical Library of Salamanca

This work presents an approach for the preventive conservation of historical constructions by means of Historical Building Information Modelling (HBIM) strategies. To this end, the methodology exploits the latest advances in inspection protocols, digitalization tools -by means of the novel back-pack mapping systems- as well as wireless monitoring networks. All this information is integrated in the HBIM environment by using ad-hoc families and interoperable communication protocols that allow obtaining a complete knowledge of the conservation status of the site. Additionally, the approach uses key performance indicators in order to evaluate the environmental conditions of the different assets presented in the site. All these features have been validated in one of the most representative heritage buildings in Spain: The General Historical Library of the University of Salamanca.

Key Parameters Featuring BIM-LCA Integration in Buildings: A Practical Review of the Current Trends

The construction sector is responsible for 40% of carbon emissions, 14% of water consumption and 60% of waste production in the world, generating a state of unsustainability. In order to keep these values under control and make the most sustainable choices starting from the earliest stages of building design, a Life Cycle Assessment (LCA) can be used. This consists of an analysis of the environmental impacts of a product, activity or process throughout all phases of the life cycle. The fundamental problem of implementing this analysis process in the construction sector is the difficulty in managing the fragmented building information that covers all aspects of buildings life stages in an integrated way. The Building Information Modeling (BIM) approach offers the possibility of managing a complex information system in an integrated manner. The BIM-LCA integration solutions proposed in recent years made LCA analysis faster, cheaper and usable by more professionals. This paper proposes an analysis of the state of the art of the research published in the last ten years regarding the integration of BIM-LCA as a methodology whereby the BIM approach can support and simplify data management for LCA analysis. The aim was to present the work methodologies tested so far and to describe all the factors that were considered in applying the BIM-LCA integration. The novelty of this review consists of identifying a series of more recurrent parameters and measures used by most researchers deriving a trend of possible and consolidated workflows. The result is, therefore, to present evidence of a general heterogenous framework and to define the common and widespread approaches identifying the main features.

GEOMATICS IN THE MANAGEMENT OF BUILT HERITAGE THROUGH BIM SYSTEMS. THE TRAINING OF NEW EXPERIENCED PROFESSIONAL FIGURES

Abstract. Geomatics is trying to redefine its role in the Italian higher-level educational system according to the new technological developments. The recent thematic thread of Building Information Modelling (BIM) systems contributes to the new role of Geomatics inside universities and, more generally, in the training process. BIM systems propose new ways of managing the construction process throughout building life cycle, from design to construction and management. They allow managing large flows of information, organized and shared among the different operators in the construction chain, through databases linked to three-dimensional objects. The BIM approach is based on two principles: interoperability and digitization.BIM was born as an application dedicated to new buildings, to promote the optimization of the entire life cycle of the building, from design to management. Many countries have been active in this sector for years, while others are now joining the digitization approach. In this complex scenario, the proposal to adopt the BIM process not only for the management of new constructions but also for the intervention on the existing one, is relevant in a country, like Italy, with a very rich history and a high presence of built historical heritage. Maurice Murphy coined the term HBIM (Historic Building Information Modelling), referring to BIM systems applied to historical buildings that need intervention and subsequent management.Geomatics plays a crucial role in HBIM as it is the primary tool for the digitization of built heritage and to obtain a model of the existing, an "as-built" model. In order to achieve this result, laser scanner and photogrammetry are the main tools, and they are involved in the so-called Scan2Bim process. The other important role is connected with the modeling stage to arrive at a three-dimensional representation suitable for common BIM authoring software while maintaining the rigor and accuracy that characterize the geomatic approach.The fundamental role of Geomatics in this context requires the training of personnel specialized in surveying and managing the acquired data through HBIM systems. There are new training courses and masters in the field of BIM systems, hosted by Politecnico di Milano at the Mantua Campus, aimed at training new figures with a specific curriculum, including Geomatics.The elements that characterize the training course are the knowledge of the principles and methods of data and the evaluation of achievable accuracy and admissible errors. It is also important to address issues that are still not completely solved in HBIM community, such as the type of modeling the best levels of detail of geometric and information content and the most practical aspects of commercial BIM authoring software.The article describes the experience carried out by Politecnico di Milano and tries to define, afterward, the training curriculum for HBIM experts, in which Geomatics plays an essential role, not only in the data acquisition phase but also in geometric and informative modeling.

The BIM2LCA Approach: An Industry Foundation Classes (IFC)-Based Interface to Integrate Life Cycle Assessment in Integral Planning

An increasing degree of digitalization in construction planning offers significant potential for building life cycle assessment (LCA) to reduce access barriers, as well as the assessment effort itself. To realize the widespread application of LCA tools and their potential to effectively minimize life cycle impacts, an open approach is required that allows for flexible application of comprehensive LCA studies and early integration in planning processes. The authors present an approach for LCA integration in all phases of digital planning which aims at a DGNB (Deutsche Gesellschaft für nachhaltiges Bauen) certification based on the open Building Information Modeling (BIM) standard Industry Foundation Classes (IFC). The approach takes into account varying levels of development and resulting data availability during integral planning phases, as well as resulting LCA application contexts. It goes beyond existing strategies and allows one to consider both BIM and LCA software through a workflow based on a single data format. The assessment framework is operationalized through standardized interface development and technical realization following the information delivery manual (IDM) process standardized for IFC interfaces. The Extensible Markup Language (XML) schema, as a specific implementation for certification, provides the target system for LCA data requirements and is generalized to a planning phase specific IDM base table. The technical realization based on respective model view definitions and distributed data suggests a pathway to the standardization of LCA-IFC integration based on an open approach. The overall approach exemplarily applies to the “LERNZENTRUM” at the Karlsruhe Institute of Technology (KIT) campus. We conclude that an open BIM approach for LCA integration in model-based planning is feasible, but requires several adjustments in IFC, LCA, and planning practice. Adding a lifecycle element to the IFC to connect BIM and LCA provides comprehensive feedback for informed decision making based on environmental impact.

Reliability evaluation index for the integrated supply chain utilising BIM and lean approaches

PurposeThis research aims to develop an approach to assess the reliability of integrated construction supply chains via an integrated model of building information modelling (BIM) and the lean supply chain (LSC). It reflects the synergistic workflow between BIM and LSC as a novel approach to improve the reliability of construction projects.Design/methodology/approachThis research evaluates the reliability of the BIM-LSC approach through a combination of entropy theory, set pair analysis (SPA), and Markov chains (EESM). An exploratory survey was conducted to collect data from 316 industry professionals experienced in BIM and LSC. Subsequently, multiple cycles of calculations were performed with indirect data inputs. Finally, a reliability evaluation index is established for the BIM-LSC approach and potential applications are identified.FindingsThe results show that the EESM model of BIM-LSC developed in this study can handle not only supply chain reliability evaluation at a given state but also the prediction of reliability in supply chain state transitions due to changing project conditions. This is particularly relevant to the current environment of the construction project, which is characterised by an increasing level of complexity in terms of labour, technology, and resource interactions.Research limitations/implicationsFuture research could consider the accuracy and validity of the proposed model in real-life scenarios with by considering both quantitative and qualitative data across the entire lifecycle of projects.Practical implicationsThe research offers a model to evaluate the reliability of the BIM-LSC approach. The accuracy of BIM supply chain reliability analysis and prediction in an uncertain environment is improved.Originality/valueThe BIM-LSC reliability evaluation and prediction presented in this study provides a theoretical foundation to enhance understanding of the BIM-LSC in the construction project context.

An Institutional Approach to Digitalization in Sustainability-Oriented Infrastructure Projects: The Limits of the Building Information Model

The transport sector accounts for a large share of global Co2 emissions. To mitigate the impact of climate change, several sustainability-oriented large-scale infrastructure projects such as electric road systems and expanding rail systems have recently been on the policy agenda. A parallel development that is expected to accelerate the transition of the transport sector is digitalization, which, although ongoing for many decades, has recently been augmented by concepts such as artificial intelligence (AI) and smart city technologies. The integration of these digitalization tools at the organizational level poses not only opportunities but also some challenges for the actors involved in infrastructure projects. An approach that is currently promoted in the infrastructure sector is the Building Information Model (BIM), which is a decision-making instrument that leverages various digitalization tools and applications. However, although the economic implications of BIM are widely discussed in the literature, the (inter-) organizational dynamics involving multiple actors in infrastructure projects are not fully grasped. Large infrastructure projects are sociotechnical endeavors embedded in complex institutional frames; hence the institutional norms, practices and logics in them are significant. Responding to this, this paper adopted an institutional analysis and put the BIM approach in the (inter-) organizational context in infrastructure delivery. Drawing on empirical data from three organizations in infrastructure delivery in Spain, this paper analyzed the tensions among actors during BIM adoption and implementation.

BIM Approach for Modeling Airports Terminal Expansion

Smart societies will make more intelligent use of Information and Communication Technology (ICT), which has the potential to transform the way to plan and manage infrastructures. New developments in computer hardware, as well as new applications and software, are changing the face of the infrastructure sector and society more generally, driving greater efficiency, increasing productivity, and greatly simplifying construction processes and life-of-asset maintenance. In European countries, the adoption of Building Information Modeling (BIM) standards have been expedited. In this research article, the architectural-structural model in a BIM environment of the elevated walkway connecting the gate with the runway, a project named “IV Bridge” under construction for the expansion of the departure area of Naples Capodichino International Airport, is carried out. Software including Autodesk family, Revit for the architectural/structural model, Robot Structural Analysis (RSA) for the analytical verification and Naviswork (NW) for the 4D/5D model were used. The effectiveness and benefits obtained by implementing the BIM methodology are discussed, showing a reduction in terms of construction times and costs.

Interoperability and data exchange within BIM platform to evaluate building energy performance and indoor comfort

Most applied strategies during the building design process require careful consideration of indoor air quality and thermal conditions. This requires a detailed analysis involving multi and interdisciplinary efforts during the design process and thus, in turn, manifold interactions among various analysis methods and their simulation tools. An undesired consequence of this activity may be major problems in terms of data clashes and data losses. These difficulties may be overcome by utilizing a three-dimensional (3D) building model that not only includes the building's functional and physical specifications but also incorporates its thermal capacity and environmental dynamics. For this, building information modeling (BIM) can be employed as a base. The interoperability of the programs thus utilized need to be identified and ensued, as this is not yet clearly defined in the literature for these complicated analysis methods. This study thus aims to improve the building design process by developing a method to determine the interoperability of the utilized programs for evaluating a building's energy performance and indoor comfort through the BIM approach. A case study is conducted to verify the applicability of the proposed method and to identify the interoperability limits during the data exchange. To this end, three main analysis models are developed and evaluated. The architecture of the building is developed with the 3D building model as specified by the building's physical conditions; the indoor comfort conditions are developed with the computational fluid dynamics (CFD) of natural ventilation as specified by temperature, humidity, and air velocity; and energy performance is developed with a building energy model specified by the building architecture and its systems. These are then all integrated through a BIM platform. Therefore, the complexity of software integration is eliminated by the BIM-based proposed methodology.

BIM data model requirements for asset monitoring and the circular economy

Purpose The purpose of this paper is to review and provide recommendations to extend the current open standard data models for describing monitoring systems and circular economy precepts for built assets. Open standard data models enable robust and efficient data exchange which underpins the successful implementation of a circular economy. One of the largest opportunities to reduce the total life cycle cost of a built asset is to use the building information modelling (BIM) approach during the operational phase because it represents the largest share of the entire cost. BIM models that represent the actual conditions and performance of the constructed assets can boost the benefits of the installed monitoring systems and reduce maintenance and operational costs. Design/methodology/approach This paper presents a horizontal investigation of current BIM data models and their use for describing circular economy principles and performance monitoring of built assets. Based on the investigation, an extension to the industry foundation classes (IFC) specification, recommendations and guidelines are presented which enable to describe circular economy principles and asset monitoring using IFC. Findings Current open BIM data models are not sufficiently mature yet. This limits the interoperability of the BIM approach and the implementation of circular economy principles. An overarching approach to extend the current standards is necessary, which considers aspects related to not only modelling the monitoring system but also data management and analysis. Originality/value To the authors’ best knowledge, this is the first study that identifies requirements for data model standards in the context current linear economic model of making, using and disposing is growing unsustainably far beyond the finite limits of planet of a circular economy. The results of this study set the basis for the extension of current standards required to apply the circular economy precepts.

Sustainability-Based Lifecycle Management for Bridge Infrastructure Using 6D BIM

A number of bridge infrastructures are rising significantly due to economic expansion and growing numbers of railway and road infrastructures. Owing to the complexity of bridge design, traditional design methods always create tedious and time-consuming construction processes. In recent years, Building Information Modelling (BIM) has been developed rapidly to provide a faster solution to generate and process the integration of information in a shared environment. This paper aims to highlight an innovative 6D BIM approach for the lifecycle asset management of a bridge infrastructure by using Donggou Bridge as a case study. This paper adopts 6D modelling, incorporating 3D model information with time schedule, cost estimation, and carbon footprint analysis across the lifecycle of the bridge project. The results of this paper reveal that raw materials contribute the most embodied carbon emissions, and as the 6D BIM model was developed in the early stage of the lifecycle, stakeholders can collaborate within the BIM environment to enhance a more sustainable and cost-effective outcome in advance. This study also demonstrates the possibility of BIM applications to bridge infrastructure projects throughout the whole lifecycle. The 6D BIM can save time by transforming 2D information to 3D information and reducing errors during the pre-construction and construction stages through better visualisation for staff training. Moreover, 6D BIM can promote efficient asset and project management since it can be applied for various purposes simultaneously, such as sustainability, lifecycle asset management and maintenance, condition monitoring and real-time structural simulations. In addition, BIM can promote cooperation among working parties and improve visualisation of the project for various stakeholders.