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Influence of wet foam incorporation on the pore structure and properties of metakaolin-based porous geopolymers

INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY 2025年第0期

作者： Soares, Gustavo de Albuquerque Bezerra, Breno Parente Lima, icaro Silva Innocentini, Murilo Daniel de Mello Luz, Ana Paula da Univ Fed Sao Carlos Grad Program Mat Sci & Engn Rodovia Washington Luiz km 235 SP-310 BR-13565905 Sao Carlos Brazil Univ Ribeirao Preto Course Chem Engn Ribeirao Preto Brazil Univ Bath Ctr Regenerat Design & Engn Net Posit World RENEW Dept Architecture & Civil Engn Bath England

Lightweight geopolymers are well-suited for construction applications, including thermal and acoustic insulation panels and fire-resistant barriers. Their porous microstructure can be tailored by incorporating gas bubbles into the fresh ceramic mixture. Several factors-such as geopolymer composition, mixing and curing conditions, and the setting behavior of the paste-play a crucial role in bubble retention within the consolidated specimens. This study investigated the processing of porous metakaolin-based geopolymers prepared with the addition of 5, 7.5, and 10 wt.% of a preformed liquid foam stabilized with xanthan gum. The addition of 0.45 wt.% xanthan gum improved foam stability, ensuring uniform pore distribution and minimizing bubble collapse during processing. This approach enabled the fabrication of specimens with low densities (0.87-1.46 g/cm(3)) and high porosity (39.49%-64.78%), significant air permeability, and well-controlled microstructural characteristics, with average pore sizes varying from 99 to 137 mu m. Based on the findings, the geopolymeric binder containing 7.5 wt.% foam demonstrated a balance of strength, low density, reduced water absorption, and engineered porosity, making it a promising candidate for sealing components or thermal insulation materials. The direct foaming method and processing conditions effectively enhanced the properties of porous geopolymers, highlighting their potential for advanced construction applications.

关键词： binder metakaolin microstructure porous geopolymer preformed foam

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Experimental, simulation, and theoretical investigations of gamma and neutron shielding characteristics for reinforced with boron carbide and titanium oxide composites

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RADIATION PHYSICS AND CHEMISTRY 2025年 226卷

作者： Ozdogan, H. Kacal, M. R. Kilicoglu, O. Polat, H. Ogul, H. Akman, F. Antalya Bilim Univ Vocat Sch Hlth Serv Akdeniz Blvd 90 TR-07085 Antalya Turkiye Giresun Univ Arts & Sci Fac Dept Phys TR-28100 Giresun Turkiye Marmara Univ Vocat Sch Hlth Serv Istanbul Turkiye Bingol Univ Vocat Sch Tech Sci Dept Architecture & Urban Planning TR-12000 Bingol Turkiye Sinop Univ Fac Engn & Architecture Dept Nucl Engn Sinop Turkiye Bingol Univ Vocat Sch Social Sci Dept Property Protect & Secur Program Occupat Hlth & Safety TR-12000 Bingol Turkiye

This study investigates the radiation shielding properties of composites containing polyester resin, boron carbide and titanium oxide in varying proportions. The radiation transmittance of the produced composites was measured using radioactive sources Am-241, Cs-137, Ba-133, Co-60, and Na-22 across a photon energy range of 59.5 keV-1332.5 keV. To analyze radiation permeability, experimental geometry was simulated using Monte Carlo-based computer codes Monte Carlo N-Particle (MCNP), Particle and Heavy Ion Transport code System (PHITS) and FLUktuierende KAskade or Fluctuating Cascade (FLUKA), and the experimental data were compared with simulation results and theoretical data obtained from WINXCOM. The findings demonstrated a high degree of consistency between experimental, simulation, and theoretical results. Notably, the BCTiO50 sample, which included a 50% addition of TiO2, emerged as the most effective in photon radiation shielding. In addition to gamma shielding, the neutron shielding properties of the produced composites were evaluated using the FLUKA code, revealing that the BCTiO0 sample, with the highest percentage of boron, provided the best neutron shielding. This analysis included composites with decreasing boron carbide content by 10%, 20%, 30%, 40%, and 50% by weight, each replaced with titanium oxide, showcasing the potential applications of these polymer composites in radiation shielding.

关键词： Radiation shielding Monte Carlo codes Boron carbide Titanium oxide Polymer composites

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Adaptive control measures and thermal comfort : Input parameters for IoT devices 18

Adaptive control measures and thermal comfort : Input parame...

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18th Iberian Conference on Information Systems and Technologies, CISTI 2023

作者： Noda, Lumy Leao, Celina Pinto Leder, Solange Federal University of Paraíba Post-graduate Program in Architecture and Urbanism - Ppgau João Pessoa Brazil School of Engineering of University of Minho Algoritmi Research Centre/LASI Guimarães Portugal Federal University of Paraíba Department of Architecture and Urbanism João Pessoa Brazil

ISBN: (纸本)9789893347928

Thermal comfort can be defined as the 'condition of mind that expresses satisfaction with the thermal environment.', and adaptive control measures comprise an adjustment to indoor environmental conditions based on occupant preferences, behavior, and feedback. The use of Artificial Intelligence (AI) and Internet of Things (IoT) in thermal comfort and adaptive control measures has the potential to significantly improve energy efficiency and occupant comfort in buildings. The adoption of the Working-from-home modality by several institutions and companies during and after the 2020 pandemic, accelerated the development of even more advanced and effective solutions in this area. This study, in its first phase, seeks to identify input parameters related to adaptive control measures adopted by the same occupants in two work environments (office building and residences) to promote personal thermal comfort contributing to the development of individual devices and IoT applications related to thermal comfort monitoring. © 2023 ITMA.

关键词： Internet of things

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Developing a machine learning-based evaluation system for the recruitment of maritime professionals

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OCEAN ENGINEERING 2024年 313卷

作者： Pekdas, Ipek Golbol Uflaz, Esma Tornaci, Furkan Arslan, Ozcan Turan, Osman Istanbul Tech Univ Dept Maritime Transportat & Management Engn TR-34940 Istanbul Turkiye Univ Strathclyde Dept Naval Architecture Ocean & Marine Engn 100 Montrose St Glasgow G4 0LZ Scotland Iskenderun Tech Univ Dept Transportat Serv Maritime & Port Management Program TR-31200 Hatay Turkiye

The maritime sector predominantly relies on subjective evaluations of seafarers' skills and experience in conventional recruiting procedures. Nevertheless, subjective evaluation methods are highly susceptible to biases and inconsistencies. This study proposes a novel recruitment process within the maritime industry by merging psychological tests and machine learning methods in the recruitment process. Using psychological tests such as MMPI-I as features in machine learning methods for the recruitment process represents a step-change approach within the industry to promote more objective assessments of maritime professionals during recruitment processes and identify suitable candidates based on data from same-rank maritime professionals. This new methodology contributes innovatively to traditional maritime sector recruitment methods and potentially addresses a significant gap in the existing literature. The proposed methodology aims to predict future values by analysing existing data sets. Data were collected from 183 volunteer cadets from different backgrounds using an application form and the MMPI-I Personality Inventory. The dataset was classified using several machine learning algorithms, and their performance metrics were compared. The top five classification algorithms (Decision tree, PNN, random forest, gradient boost trees, and naive Bayes) with the best performance were evaluated, and the most accurate classification performance was achieved with the GBT algorithm. The results show that the highest values are for Gradient Boosted Trees (86%) and Random Forest (80%). The GBT algorithm has scored higher values for other metrics as well. The findings of this study indicate that it is possible to train algorithms that can adequately forecast the credentials and appropriateness of marine recruits. Through more development, these data-driven solutions could enhance existing subjective recruitment practices. This approach could improve the objectivity and predictio

关键词： Machine learning Maritime industry recruitment MMPI personality assessment Human resources analytics

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Normal tensile bond behaviour of CFRP-epoxy laminate to concrete and steel

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INTERNATIONAL JOURNAL OF ADHESION AND ADHESIVES 2024年 132卷

作者： Jati, Dinar Gumilang Purnomo, Joko Gan, Buntara S. Leksono, Lintang B. Han, Ay Lie Univ Atma Jaya Yogyakarta Fac Engn Dept Civil Engn Yogyakarta 55281 Indonesia Petra Christian Univ Surabaya Indonesia Nihon Univ Coll Engn Dept Architecture Koriyama 9638642 Japan Univ Diponegoro Fac Engn Dept Civil Engn Semarang 50275 Indonesia Univ Diponegoro World Class Res Program Semarang 50275 Indonesia

The effectiveness of CFRP sheets as external concrete reinforcement is determined by the CFRP-concrete bond behaviour. In this study the normal tensile bond of CFRP-epoxy laminate was assessed through the behaviour of the CFRP-concrete, and CFRP-steel bond. A pull -off apparatus combined with a newly introduced method using a clip -on displacement transducer was employed. The specimen was a field-impregnated single CFRP sheet attached to concrete and steel. The contribution of the epoxy was tested individually. The load-displacement behaviour, the ultimate strength, failure mode and the individual component 's contribution to the CFRP bond, were analysed. The study concluded that for a concrete compression strength as high as 50 MPa the failure was designated by concrete rupture. For the CFRP-steel specimens, the failure was distinguished as adhesive interface failure or CFRP failure, influenced by the degree of epoxy impregnation and steel surface preparation. The load-displacement behaviour of the CFRP-concrete, CFRP-steel and epoxy were characterized by nonlinearity with no post peak. The presence of CFRP sheets enhanced the stiffness of the individual epoxy. The presence of CFRP-epoxy has a negative affected to the normal tensile stiffness of concrete, but postponed the load levels at which first concrete cracking occur, regardless the concrete compression strength.

关键词： CFRP Tensile bond Epoxy Concrete Load-displacement

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Climate Change Adaptation in the Built Environment: Lessons from a Geographical Transect of Indus River Basin Settlements

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INTERNATIONAL JOURNAL OF ISLAMIC architecture 2024年第1期13卷 5-20页

作者： Wescoatjr Jr, James L. MIT Aga Khan Program Islamic Architecture Room 10-39077 Massachusetts Ave Cambridge MA 02139 USA

In July 2022, flash floods tore through mountainous areas of the upper Indus basin and Balochistan. At about the same time, monsoon storms inundated Karachi in what is becoming an annual occurrence in the poorly drained cities of South Asia and around the world. In August of that year, historically unprecedented monsoon rains flooded the provinces of Balochistan and Sindh, affecting some 33 million people in the country of Pakistan. The previous mega-flood in Punjab had occurred in 2010, only twelve years before, beginning as monsoon flash floods in Khyber-Pakhtunkhwa that ultimately cascaded through the Indus floodplains across much of southern Punjab and northern Sindh..... Poised as we are in this challenging period of great change, what are the possibilities for refocusing attention on climate change in Islamic environmental design? They are many. As an illustrative regional exploration, it is useful to survey the range of creative adaptations across a broad geographical transect of conditions, from high mountains to coastal deltas, and laterally across the humid to arid plains and floodplains of the Indus River basin region.

关键词： adaptation basin transect climate change historical geography Indus River settlement planning

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Preservation of the manifestation of Balinese cultural traditions in the current architecture of public buildings: a case study of the Mandala Agung building of the Puri Ahimsa resort in Mambal Village - Bali

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JOURNAL OF ARCHITECTURAL CONSERVATION 2021年第1-2期27卷 53-65页

作者： Suryono, Alwin Parahyangan Catholic Univ Fac Engn Architecture Study Program Bandung Indonesia

The Mandala Agung at Puri Ahimsa displays the concept of 'architecture being non-architectural' yet it remains based on Balinese culture. This paper reveals the forms of local traditions in the lay-out and preservation of these buildings in a qualitative-descriptive manner. The Balinese physical-social value system is revealed through sense-purpose-essence-awareness. The lay-out of Puri Ahimsa signifies Cosmic Balance through the harmonious relations between humans, God, and nature. Architecturally, Mandala Agung is a synthesis of the rice cone form and the openness of Balinese traditional pavilions (wantilan), applying the Cosmic Balance through space in forming harmonious relationships. Singling out the roof as the divine realm, the inner space is regarded as a human realm (Tri Loka concept). The semi-circular space with the doors in opposite directions signifies the balance of opposing forces. Natural balance and the Tri Hita Karana philosophy are maintained in the Puri Ahimsa lay-out. The shape and the openness of the wantilan are adapted to the Mandala Agung architecture, while the Nawa Sanga concept is adapted to the eight main pillars and the sky-light roof. Tri Hita Karana is maintained in the inner space, and the philosophy of Desa Kala Patra is concretised through its uniqueness for today's activities.

关键词： Culture human nature God conservation

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Function or folly? Philip Johnson's pavilion for pre-Columbian art in Washington DC

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MUSEUM HISTORY JOURNAL 2021年第1-2期14卷 20-36页

作者： Travis, Stephanie George Washington Univ Interior Architecture Program Washington DC 20052 USA

Nestled within the gardens of Dumbarton Oaks in Washington DC is a modern pavilion for viewing art, designed by Philip Johnson in 1963. Johnson utilised a circular module organised into a three-by-three grid, with an open courtyard in the centre. Each module is encased by glass walls, as Johnson wanted to merge nature and architecture. The building is outfitted in a minimal palette of luxurious materials, with an aesthetic that pulls stylistically from Johnson's travels. With no programmatic or budgetary constraints, Johnson was able to design conceptually, similar to his own projects where he designed small structures with little purpose, termed follies. Critically acclaimed yet lesser-known, the pavilion has not been analysed as a museum. As such, this article asks the question, is this structure merely a folly or does it function as a space to exhibit and view the pre-Columbian objects in the collection?

关键词： Museums exhibit design architecture interior design pre-Columbian art

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Safety performance framework at construction site for self-regulation by building developers

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ENGINEERING CONSTRUCTION AND ARCHITECTURAL MANAGEMENT 2022年第9期29卷 3394-3414页

作者： Mahmoud, Abubakar Sadiq Hamdan Ahmad, Mohd Mohd Yatim, Yahya Aminu Dodo, Yakubu King Fahd Univ Petr & Minerals Dammam Community Coll Safety Technol Program Dhahran Saudi Arabia Univ Teknol Malaysia Fac Built Environm & Surveying Skudai Malaysia Univ Teknol Malaysia Fac Built Environm & Surveying Main Campus Skudai Skudai Malaysia Istanbul Gelisim Univ Fac Engn & Architecture Dept Architecture Istanbul Turkey

Purpose This study proposes a self-regulatory framework to enhance safety performance at the construction stage among building developers. Design/methodology/approach Extant literature identified 137 potential factors that influence the construction safety performances of building developers. Focus group discussions and interviews were conducted with 11 panels of experts and professionals. The Relative Importance Index (RII) was used to analyse the response feedback described in a similar paper. In this study, the survey tool used was set up with 40 variables grouped into eight latent variables in the framework, which were agreed and certified as "extremely important" by the panel. Based on random sampling, data were collected from 229 valid respondents. Structural equation modelling (SEM) technique using Smart PLS software was then used to analyse the respondent's feedback. Findings The results show that safety administration and processes, effective communication of safety behaviour, significantly influenced safety performance on a construction site with beta values of 0.330 and 0.431 along with t values of 3.005 and 2.547 at p < 0.1, respectively. These factors, among others, provide a distinct approach to understanding and improving on-site construction safety. The study findings will potentially benefit building professionals and other stakeholders by improving awareness of safety practices. Research limitations/implications The study may not have covered all possible factors that influence the construction safety performance of building developers. Also, the generalizability and transferability of the research outcome to the construction industry wide use is also limited when reference is made to the characteristics of the research respondents and/or participants. In addition, validation of the framework by five professionals is rather small. Practical implications Theoretically, the framework through the identified factors provide a distinct approach to under

关键词： Safety performance framework Self-regulations Health and safety Construction safety performance Building developers

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A mathematical study of a two-layer fluid flow system in the presence of a floating breakwater in front of VLFS

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Applied Mathematical Modelling 2023年第1期122卷 706-730页

作者： Barman, Koushik Kanti Chanda, Ayan Tsai, Chia-Cheng Center of Excellence for Ocean Engineering National Taiwan Ocean Unviersity Keelung Taiwan Department of Ocean Engineering and Naval Architecture Indian Institute of Technology Kharagpur West Bengal India Bachelor Degree Program in Ocean Engineering and Technology National Taiwan Ocean University Keelung Taiwan

The present study deals with the usefulness of a surface-piercing porous structure of definite width in a two-layer fluid placed at a finite distance from a floating elastic plate to mitigate the hydrodynamic response of the elastic plate. We use linear water wave theory with the eigenfunction expansion approach to develop analytical solutions to the model problem in finite water depth. Here, we identify and explore the complete parameter space associated with the problem by examining the hydrodynamic coefficients for waves in surface and internal modes, plate elevation, shear force, bending moment, wave loads on the elastic plate, flow amplitude in the plate-covered region and wave attenuation. We investigate the effectiveness of structures of various configurations and geometries on wave scattering. This study demonstrates an oscillatory pattern of wave reflection in the confined region between the plate and the breakwater. Moreover, optima in the oscillatory pattern can be observed due to the resonating interaction of waves and the breakwater-plate system. Furthermore, the research shows that an ideal width and distance between the breakwater and floating plate can be calculated while assuming an appropriate configuration of the porous structure to create a breakwater-plate system with a reasonable efficiency that possesses both reflection and dissipation properties. The design of various types of coastal structures employed in the marine environment for the reflection and dissipation of wave energy at continental shelves dominated by stratified fluid, described here as a two-layer fluid, will significantly benefit from the findings of the current study. © 2023 Elsevier Inc.

关键词： Eigenvalues and eigenfunctions

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