Construction Techniques Research Articles

Evaluation of patient satisfaction and maximum biting force of three differently constructed bars on two implants retaining mandibular overdenture - one year follow-up (a randomized controlled clinical trial)

BackgroundDifferent bar construction techniques will affect the bar passive fitness, which may induce stresses or strain on the implant and/or tightening screw and sequentially may affect the biting force and patient satisfaction.Aim of the studyThis clinical investigation assessed patient satisfaction and maximum biting force (MBF) using three differently constructed (conventional casting, milling, and 3D printing CAD/CAM techniques) cobalt-chromium (Co-Cr) bar-retained implants mandibular overdentures over a one-year period of follow-up.Materials and methodsThirty edentulous patients seeking for two implants bar-retained mandibular overdentures were randomly assigned into three groups as the following: Group I: 10 patients received a Co-Cr conventional casting bar, Group II: 10 patients received a Co-Cr CAD/CAM milled bar, and Group III: 10 patients received a Co-Cr CAD/CAM 3D-printed bar. All the bar groups were connected to two implants in the canine area bilaterally. Within the first two weeks following implant placement, patients received the definitive prosthesis. Patient satisfaction was evaluated by using the (OHIP-EDENT-19) questionnaire form after 6, and 12 months. Additionally, the maximum biting force was tested at after delivery, 3, 6, and 12 months for each group. The results were collected, tabulated, and statistically analyzed. Trial registration: This study was recorded on ClinicalTrials.gov retrospectively registered (ID: NCT06401187) on 30/04/2024.ResultsAfter one year follow up, regrading patient satisfaction the three groups showed no statistically significant difference. Although, the functional limitation domain was in favor of the milled bar. Regarding the maximum biting force, no statistically significant difference was found among three groups. However, at 12 mouths follow-up the milled bar showed statistically value.ConclusionWithin the limitations of this study, the conventional, milled and 3D printed bar overdentures groups can be used as a satisfactory treatment modality for edentulous mandible in terms of patient satisfaction and maximum biting force.

Unraveling University EFL Teachers’ Feedback Beliefs in Teaching English Argumentative Writing

ABSTRACTTeachers’ beliefs about feedback can affect both the way they provide feedback and its effectiveness in improving students’ writing proficiency. However, research remains scant on belief–practice relationships. This study attempted to fill the gap by investigating such relationships with a sample of 112 Chinese university EFL teachers in teaching argumentative writing. Data were collected through a writing feedback beliefs and practices questionnaire, an argumentative writing teaching beliefs questionnaire, and semi‐structured interviews. The participants were selected using convenience sampling from six universities in Northern China. Quantitative data were analyzed through confirmatory factor analysis, multiple regression, and repeated measures ANOVA to examine the characteristics of these teachers’ writing feedback beliefs and the relationships between the beliefs and relevant practices. Qualitative data from the interviews were analyzed thematically to gain deeper insights into the belief–practice relationships. Results indicated that most teachers believed their feedback was crucial for improving students' argumentative writing, particularly regarding communicative purposes, discourse organization, linguistic expressions, argument construction, and rhetorical techniques. However, a discrepancy was noted between teachers' feedback beliefs and their practices, especially concerning linguistic expressions. These findings highlight the need for targeted support to better align teachers' feedback beliefs with their practices for more effective teaching of EFL writing.

Research on the early age mechanical properties of concrete based on hydration kinetics

Abstract. In the era of advanced construction techniques, the enhancement and regulation of the functionality of concrete, a widely utilized construction material, has gained significant prominence. The study delves into the exploration of the properties and heat reaction behavior during hydration of various composite cementitious materials with the incorporation of three distinct mineral additives: microspheres, cellulose, and early strength shrinkage reducing agent for early strength enhancement. Analyzing the impact of cement hydration reactions on the early-age performance of concrete, the Krstulovic-Dabic hydration kinetics model was utilized to simulate and study the hydration process of the composite cementitious system in concrete. The findings reveal that the introduction of microspheres and cellulose hinders the advancement of early-age strength in concrete, whereas the utilization of an early strength shrinkage reducing agent proves to be beneficial in enhancing early-age strength. Enhancing the hydration reaction rate is observed with the addition of early strength shrinkage reducing agent, whereas the presence of microspheres and cellulose slows down this process. The rate of hydration reaction accelerates, resulting in a greater early-age strength of the concrete.

Petrification in Contemporary Set Theory: The Multiverse and the Later Wittgenstein

Abstract This paper has two aims. First, we argue that Wittgenstein’s notion of petrification can be used to explain phenomena in advanced mathematics, sometimes better than more popular views on mathematics, such as formalism, even though petrification usually suffers from a diet of examples of a very basic nature (in particular a focus on addition of small numbers). Second, we analyse current disagreements on the absolute undecidability of CH under the notion of petrification and hinge epistemology. We argue that in contemporary set theory the usage of construction techniques for set-theoretic models in which the Continuum Hypothesis holds and those in which it fails have petrified into the normative demand that CH remain undecidable. That is, the continuous and successful practices involving the construction of various set-theoretic models now act as a normative hinge shared among practitioners, i.e., have normative force in the discipline. However, not all hinges are universal, which is why we find disagreements in set theory. We will show that this is a refinement of, and partially conflicts with, the arguments presented by set theorist Joel David Hamkins.

Pre-Planning and Post-Evaluation Approaches to Sustainable Vernacular Architectural Practice: A Research-by-Design Study to Building Renovation in Shangri-La’s Shanpian House, China

The renovation and revitalization of vernacular architecture are pivotal in sustainable rural development. In regions like Shangri-La, traditional structures not only safeguard cultural heritage but also provide a foundation for enhancing local communities’ living conditions. However, these villages face growing challenges, including infrastructure decay, cultural erosion, and inadequate adaptation to modern living standards. Addressing these issues requires innovative research approaches that combine heritage preservation with the integration of contemporary functionality. This study employs a research-by-design approach, focusing on the Shanpian House as a case study, to explore how pre-planning and post-evaluation methods can revitalize traditional vernacular architecture. The pre-planning phase utilizes field surveys and archival research to assess spatial, cultural, and environmental conditions, framing a design strategy informed by field theory. In doing so, it evaluates how traditional architectural elements can be preserved while introducing modern construction techniques that meet current living standards. The post-evaluation phase, conducted through questionnaires and semi-structured interviews, assesses user satisfaction, focusing on the impact of architectural esthetics, structural stability, and material choices. Key findings from an OLS regression highlight the strong positive correlation between architectural style, structural choices, and cultural relevance with resident satisfaction. The research emphasizes that design elements such as structural details, materials, and infrastructure upgrades are critical in shaping perceptions of both functionality and cultural identity. Interestingly, the model reveals that improving architectural esthetics, alongside modern indoor features such as network connectivity, has a significant impact on enhancing overall resident satisfaction (significance level: 0.181). This study contributes to the broader discourse on sustainable building renovation by demonstrating how traditional architecture can be thoughtfully adapted for contemporary use and also proposes a paradigm shift in the renovation of historic buildings, advocating for a balance between preservation and modernization. The application of sustainable materials, digital modeling, and innovative construction techniques further ensures that these traditional structures meet the demands of modern civilization while maintaining their cultural integrity.

Critical construction waste minimization strategies for a circular economy in developing countries: A contractor’s perspective in China

AbstractDeveloping countries are often burdened by substantial construction waste (CW) generated through urbanization and urban renewal activities, highlighting the urgent need for effective CW minimization strategies to facilitate their transition towards a circular economy. Although previous studies have examined similar topics at various stages of construction projects from different perspectives, a comprehensive study integrating all critical stages from a contractor’s perspective is still lacking. To fill this gap, this study aims to identify critical CW minimization strategies in developing countries, with a holistic concentration on the planning, design, and construction stages, using China as a case study. æThe research began by compiling a comprehensive list of CW minimization strategies tailored to developing countries, based on an extensive desktop survey and a focus group interview, resulting in 32 strategies. A subsequent questionnaire survey with leading CW management experts and rigorous statistical analyses have identified 9 strategies as critical for minimizing CW in developing countries. Finally, through exploratory factor analysis, seven fundamental principles for CW minimization have been established: “Planning for CW Minimization” for the planning stage; “Optimized Design of Building Structures,” “Optimization of Design Process,” and “Stakeholders’ Efforts in the Design Stage” for the design stage; and “Optimization of Construction Techniques,” “Stakeholders’ Efforts in the Construction Stage,” and “Efforts on CW Disposal” for the construction stage. This study offers valuable insights for stakeholders in developing countries, empowering them to effectively minimize CW through targeted strategies, facilitating the transition to a circular economy and supporting the realization of the "zero-waste city" goal.

Automatic construction and verification algorithm for smart contracts based on formal verification

As an emerging technology, blockchain demonstrates strong potential for applications in digital finance. As a core component of blockchain, the security and reliability of smart contracts is crucial. To ensure the high reliability of smart contracts, this study employs formal construction and verification techniques based on game theory. Initially, the profit function is defined using distortion techniques, and a game model for supply chain participation is designed. However, the equilibrium solution of the two-party game does not represent the optimal solution for the supply chain system. Therefore, the study introduces third-party participation to optimize the equilibrium solution. Finally, a probability model detection method is used to verify the constructed smart contract model. The results show that the supply chain model, analyzed through formal methods, has attributes consistent with theoretical analysis. Consequently, the research on automatic construction and verification algorithms for smart contracts based on formal verification proves to be effective and feasible in practical applications.

Design, performance, processing, and validation of a pooled CRISPR perturbation screen for bacterial toxins.

Unbiased forward genetic screens have been extensively employed in biological research to elucidate functional genomics. In pooled clustered regularly interspaced short palindromic repeats (CRISPR) perturbation screens, various genetically encoded gain-of-function or loss-of-function mutations are introduced into a heterogeneous population of cells. Subsequently, these cells are screened for phenotypes, perturbation-associated genotypes are analyzed and a connection between genotype and phenotype is determined. CRISPR screening techniques enable the investigation of important biological questions, such as how bacterial toxins kill cells and cause disease. However, the broad spectrum of effects caused by diverse toxins presents a challenge when selecting appropriate screening strategies. Here, we provide a step-by-step protocol for a genome-wide pooled CRISPR perturbation screen to study bacterial toxins. We describe technical considerations, pilot experiments, library construction, screen execution, result analysis and validation of the top enriched hits. These screens are applicable for many different types of toxins and are anticipated to reveal a repertoire of host factors crucial in the intoxication pathway, such as receptors, trafficking/translocation factors and substrates. The entire protocol takes 21-27 weeks and does not require specialized knowledge beyond basic biology.

Advanced Transfer Learning Strategies for Improving Deep Learning Model Efficiency and Accuracy

Machine learning primarily focuses on supervised learning, which relies on labeled data, while unsupervised learning addresses data without labels. Reinforcement learning, on the other hand, develops agents that learn optimal actions based on past experiences. Transfer learning, distinctively, enhances learning in a target task by leveraging knowledge from related source tasks. In recent years, many machine learning models have remained single-task focused. This paper explores scenarios in which transfer learning can be applied effectively from a source domain to a target domain, employing feature selection, extraction, and construction techniques. These methods enable transformation into a new feature space by generating a refined subset of the original features.

Integrating modular and prefabricated construction techniques in affordable housing: Architectural design considerations and benefits

Integrating modular and prefabricated construction techniques in affordable housing: Architectural design considerations and benefits

The Characterization of the Building Materials Used in the Refectory of the Manzana Jesuítica in Córdoba (Argentina) on the Basis of a Study of Its Historical Background and the Archaeological Evidence

This paper explores the historical and geological background of the refectory of the Manzana Jesuítica in the city of Córdoba (Argentina), as a basis for characterising some of the building materials used in it. The aim is to gain a better understanding of the raw materials, labour, and production methods employed by the Jesuits in the seventeenth and eighteenth centuries. To this end, six fragments containing brick, render, and paint layers were studied by X-ray diffraction and using optical and scanning electron microscopies. Our results show that the ceramics differed solely in terms of their firing temperature, while the mortars were either air lime- or gypsum-based. The paints, mainly lime-based with clays, have similar mineralogical compositions, with some differences in colour due to the presence of goethite. This study demonstrates that the Jesuits, through their strategically situated settlements in the province of Córdoba, developed an economic system for the extraction and transport of raw materials, centred around the use of local resources. This, combined with construction techniques imported from Spain and adapted to local circumstances, was a sign of the adaptability of the Jesuit Order and their lasting influence on the region. Understanding the materials and techniques used by the Jesuits provides valuable insight into the methods of construction employed in historical buildings, offering key perspectives for their conservation. Moreover, it highlights the significance of local resource management in the longevity and preservation of these architectural works.

Experiments and FE Modeling on the Seismic Behavior of Partially Precast Steel-Reinforced Concrete Squat Walls

This paper proposed an innovative precast steel-reinforced concrete (PPSRC) squat wall to simplify on-site construction. In PPSRC squat shear walls, the hollowly precast RC wall panel can be assembled on-site through the pre-erected steel shapes, and the boundary cores will be filled using fresh concrete together with the slab system. The seismic performance of PPSRC squat walls, influenced by different construction techniques (cast-in-place vs. precast) and steel ratios, was examined through pseudo-static experiments on three specimens. Some key performance indicators, including hysteretic behavior, skeleton curves, stiffness degradation, energy dissipation, and load-carrying capacity, were analyzed in detail. The test results indicated that all the PPSRC squat walls failed in typical shear failure, and no significant slippage between the precast and fresh concrete sections was observed during the loading process, indicating that the composite action could be fully achieved via the novel throat connectors. In addition, the PPSRC squat walls could achieve comparable seismic performance compared with that of cast-in-place SRC shear walls (the peak load of the PPSRC squat wall only increased by 0.26% compared with the control specimen), and the load-carrying capacity and deformability could be enhanced by increasing the steel ratio in the boundary elements. Finally, an elaborate finite element model was developed and validated using ABAQUS software. The parametric analysis of the concrete strengths of precast and cast-in-place parts and the axial load was conducted further to investigate the seismic performance of PPSRC squat walls.

Optimization of MBE-grown GaSb buffer on GaAs substrates for infrared detectors

The aim of this work was to improve the quality of the GaSb buffer layers on GaAs substrates using the molecular beam epitaxy (MBE) technology. The high quality of the GaSb buffer layers is one of the most important elements enabling the synthesis of good quality of type II superlattices (T2SL) structures for infrared applications. The main challenges in this regard are: compensation of the difference in lattice constants between GaAs and GaSb and obtaining the highest achievable surface quality of the final GaSb layer. In the literature, many authors describe different techniques to obtain the best quality of a GaSb buffer layer. In this work, we present the results of HRXRD, AFM, TOF-SIMS, SEM, and Nomarski optical microscope measurements obtained for 2 μm thick GaSb buffer layers. The GaSb layers are made according to different techniques and these results are compared with a GaSb buffer construction technique according to our own technology. During the processes, we also obtained an unintentional structure of one of the buffer layers, which allowed us to obtain very good results in terms of surface structure and crystallographic quality where FWHM in ωRC scan was equal to 138 arcsec and RMS 0.20 nm proving that there is still a lot of work to be done in this area.

Data-driven Prediction of Underwater Navigation Fitness Zone Classification

This article presents a pioneering approach to enhancing underwater navigation accuracy and stealth through the utilization of gravity anomaly data. Developed by researchers from leading universities in China, the study aims to revolutionize autonomous marine navigation systems in unknown sea areas. By integrating advanced data processing, feature extraction, model construction, and optimization techniques, a cutting-edge navigation system has been formulated, showcasing remarkable improvements in navigation precision.The core innovation lies in leveraging bicubic interpolation to refine data resolution, enabling a meticulous evaluation of regional suitability and segmentation of sea zones. Subsequently, a gradient-based suitability prediction model is constructed, which is validated through migration prediction, underscoring its effectiveness and reliability. This research not only addresses the limitations of traditional terrain matching navigation methods, plagued by data accuracy and resolution constraints, but also paves the way for advancements in oceanic exploration and technological competitiveness.The introduction of gravity anomaly data, coupled with machine learning and visualization tools, marks a significant step forward in the development of adaptive navigation zones. This innovative system holds immense potential to enhance the autonomy, accuracy, and concealment of underwater vehicles, thereby facilitating safer and more efficient oceanic missions in the future.

Accelerated construction and geometry control of cable-stayed bridge: cable crane method

Mountainous regions with rugged terrain, steep valleys and restricted access to roads and rivers present distinctive challenges for segmented erection of cable-stayed bridges (CSBs). In recent years, the cable crane method (CCM) has emerged as an innovative solution for CSB construction to address the difficulties associated with vertically lifting and horizontally delivering girder segments in such challenging environments. However, integrating the CCM with a CSB introduces a coupling effect, significantly complicating the control of bridge geometry. In this work, the accelerated construction and geometry control for CSBs employing the CCM in mountainous regions were systematically studied. The characteristics of 1521 bridges in mountainous regions were investigated, followed by a numerical analysis of geometry control and field measurements of as-built geometries, forces and ambient conditions during construction. Critical techniques for CSB construction using the CCM are also clarified. The mechanical behaviour of a bridge during construction was comprehensively evaluated to improve geometry control. The numerical results were validated through field measurements, offering valuable insights for future CSB practices using the novel CCM.

The comparison of surgical correction of recurrent pectus excavatum with crossing wire construction and ravitch technique

Aim of the study. The article compares the method of surgical treatment using a crossing wire construction with the modified Ravitch operation for recurrent pectus excavatum. Methods. Between 2010 and 202, in our center twenty-four patients with recurrent pectus excavatum were operated. 15 patients underwent modified Ravitch technique with sternocostal plate and 9 patients were operated by open toracoplasty with crossing wire construction. The primary end point was Haller index change after operation. The secondary end points included length of stay after operation, short-term and long-term complications. Results and discussion. The mean patient age was 19.1±2.87 years. The mean Haller index was 4.45±2.78, the Gizhitskaya index – 0.7±0.1. A toracoplasty with cross wire construction was performed in 9 patients. There was no perioperative death. The Haller index reduced to 2,9±1,76 after the operation. During the follow-up, there were 1 patient who developed wound marginal necrosis; hemothorax in 2 patients and pneumothorax in 1 patient. Conclusions. Reoperation for recurrent pectus defects is a challenging undertaking. The results of our study showed that patients with recurrent pectus excavatum can safely undergo reoperation by toracoplasty with cross wire construction, and achieve satisfactory results.

Self-supporting thin Shells in Italy. Space and Structure of the Industrial Buildings (1930-1970)

In the Twentieth Century, the industrial buildings featured a broad experimentation on the load-bearing structures suited to the production spaces. Among the structural elements explicitly designed for factories were reinforced concrete thin shells. In Italy, where reinforced concrete was the predominant construction technique for the entire century, the evolution of the thin shells for industrial buildings traced a significant story: starting from the introduction of foreign systems and patents in the 1920s, the design and construction of the thin shells gradually stacked to national productive and technological specificities. This paper presents a historical investigation of the application of thin shells in Italy between 1930 and 1970, remarking, thus, the local contribution of Italian contractors and designers in the evolution of both the design solutions and production process. Furthermore, the study presents a systematic historical and technical framework related to thin shells to support the actions of knowledge and safeguard the industrial building heritage.

Pre-Roman U-Th datings of an aqueduct near ancient Lebedos (Aegean Region, Türkiye)

In the vicinity of the ancient city of Lebedos, known as one of the twelve Ionian cities, located south of İzmir in W. Anatolia (Türkiye), the NE-SW-trending active Tuzla Fault zone is characterized by numerous hot springs and associated travertine-type carbonate deposits (sinter). Among these, the active Doğanbey bath features an approximately 560 m-long hot water aqueduct, called the “Roman Aqueduct”. This structure is distinct from the well-known Roman (Byzantine) ruins (Karakoç bath) in the area in terms of its materials and construction techniques. Despite the absence of detailed archaeological or geochronological studies in this region, the Doğanbey bath and aqueduct have conventionally been attributed to the Roman era.The trough and sidewalls of the Doğanbey aqueduct are covered with a 5–25 cm-thick, laminated sinter crust, formed by the flow of hot water. Each sinter lamina comprises radial structures of calcite and/or aragonite, resembling feather-like shrub structures. This study employs the U-Th chronometry to determine the age of sinter layers covering the Doğanbey bath aqueduct. Two layers from a single sinter sample of the ancient Doğanbey aqueduct yielded U-Th ages of 2717 ± 106 and 2528 ± 106 years (BP). These dates indicate a pre-Roman phase of settlement in the Lebedos area, a finding documented for the first time through this study.

Accounting Method and Indicators of Multilevel CO2 Emissions Based on Cost During Construction of Shield Tunnels

With the rapid expansion of shield tunnel projects in China, precise accounting of CO2 emissions throughout the entire process is essential for advancing green and low-carbon construction practices. This paper introduces an innovative CO2 accounting methodology utilizing a cost-based carbon emission coding system. It adopts a multilevel approach to carbon emission accounting, aligned with this coding system, which facilitates a detailed examination of carbon emission ratios and characteristics across various construction techniques. The analysis includes six typical shield tunnel projects varying in diameter, focusing on sub-projects to scrutinize CO2 emissions and establish specific indicators. The findings indicate that CO2 emissions per 10,000 yuan of investment, approximately 30.25% (or 3025 kgCO2e/10,000 yuan), are more consistent than those per unit of length. Moreover, the study highlights differing CO2 emission trends among sub-projects compared to whole tunnel projects, assessing emission indicators and distribution patterns in four sub-projects: shield excavation, segmental lining, internal structure, and tunnel reinforcement. From these findings, the paper suggests more precise and tailored strategies for CO2 reduction. This research provides a theoretical basis for future construction planning and carbon management strategies.

Preventive Preservation of Rammed Earth Historical Heritage Through Continuous Monitoring, Architectural Inspections, and Data Fusion

Rammed earth construction, an ancient and sustainable building technique, faces significant preservation challenges, particularly in historical contexts. This study aims to enhance the preventive preservation of rammed earth historical heritage through a comprehensive methodology combining continuous monitoring, architectural inspections, and data fusion. By integrating nondestructive testing techniques such as ultrasound, thermography, and ground-penetrating radar with operational modal analysis and modeling, the proposed approach allows for early detection and assessment of structural vulnerabilities. This methodology was applied to the Tower of Muhammad in the Alhambra of Granada, Spain, demonstrating its effectiveness in identifying and quantifying damage and predicting structural health. Using multi-source data (documentation, inspections, nondestructive tests, and continuous monitoring), a finite element model was built, calibrated (achieving an avg. error in modal frequencies of 1.28% and a minimum modal assurance criterion value of 0.94), and used to develop a surrogate model able to predict the modal properties of the tower in 0.02 s, becoming compatible with continuous system identification. The presented results highlight the importance of continuous data acquisition and advanced diagnostic tools for safeguarding rammed earth structures against environmental and anthropogenic threats. This study advocates for the adoption of digital twins in historical preservation, facilitating informed decision-making and sustainable management of cultural heritage.