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53 result(s) for "Liu, Boda"
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A BIM-Based Approach to Automated Prefabricated Building Construction Site Layout Planning
Construction site layout planning (CSLP) is a typical problem in construction site management that urgently needs to be solved. A reasonable construction site layout can improve efficiency and reduce costs and unnecessary loss of time. To solve the CSLP problem, some emerging optimization algorithms and enhanced mathematical models have been developed. The building information model (BIM) provides data support for the implementation of previous research. However, manually extracting and modifying parameters from the BIM for use in optimization algorithms is cumbersome in practical applications, wasting considerable time and human resources. In this paper, we propose a framework of automated prefabricated building CSLP to realize the integration of the BIM and an optimization algorithm, which utilizes the Dynamo visual programming platform to create an information channel between the BIM and the optimization algorithm. A typical and practical case, which is optimized by the genetic algorithm (GA) and particle swarm optimization (PSO), is demonstrated to validate the proposed approach and to show an effective reduction in material transportation cost and unnecessary loss of time.
Computer Vision-Based Construction Process Sensing for Cyber–Physical Systems: A Review
Cyber–physical systems (CPSs) are generally considered to be the next generation of engineered systems. However, the actual application of CPSs in the Architecture, Engineering and Construction (AEC) industry is still at a low level. The sensing method in the construction process plays a very important role in the establishment of CPSs. Therefore, the purpose of this paper is to discuss the application potential of computer vision-based sensing methods and provide practical suggestions through a literature review. This paper provides a review of the current application of CPSs in the AEC industry, summarizes the current knowledge gaps, and discusses the problems with the current construction site sensing approach. Considering the unique advantages of the computer vision (CV) method at the construction site, the application of CV for different construction entities was reviewed and summarized to achieve a CV-based construction site sensing approach for construction process CPSs. The potential of CPS can be further stimulated by providing rich information from on-site sensing using CV methods. According to the review, this approach has unique advantages in the specific environment of the construction site. Based on the current knowledge gap identified in the literature review, this paper proposes a novel concept of visual-based construction site sensing method for CPS application, and an architecture for CV-based CPS is proposed as an implementation of this concept. The main contribution of this paper is to propose a CPS architecture using computer vision as the main information acquisition method based on the literature review. This architecture innovatively introduces computer vision as a sensing method of construction sites, and realizes low-cost and non-invasive information acquisition in complex construction scenarios. This method can be used as an important supplement to on-site sensing to further promote the automation and intelligence of the construction process.
A Model for Melt‐Preferred Orientation and Permeabilities in Deformed Partially Molten Peridotites
In a deforming partially molten rock, melt concentrates into a grain‐scale melt pocket aligned at a preferred orientation (melt‐preferred orientation, or MPO). However, observing this texture alone provides limited information on the 3D orientation and geometry of these melt pockets, which are critical parameters for estimating permeability. Here, we modeled the MPO of experimentally deformed peridotites by simulating melt streaks arising from melt pockets of various shapes and 3D orientations. The model aims to identify 3D distribution and characteristics of melt pockets that could account for the observed length, thickness, and the probability of melt streaks. Results show that melt pockets at preferred orientation exhibit greater length, thickness, and number density compared to those perpendicular. These results can be incorporated into the simulation of melt flow through individual melt pockets, which allows us to estimate the permeability corresponding to the observed MPO. We found that the permeability of vertically compressed peridotites increases with increasing compressive strain and a more elongated and thickened shape for melt pocket aligned at preferred orientation. The vertical permeability in the sample with 30% compressive strain is at least 40 times larger than that of an undeformed sample. For peridotites deformed under simple shear, the permeability exhibits an anisotropy of at least three. Such anisotropic permeability, coupled with the formation of melt‐rich bands and other melt channels, is believed to cause lateral melt focusing beneath mid‐ocean ridges. Plain Language Summary The distribution of melt at the grain scale controls the permeability in partially molten rock. While observe melt streaks on thin sections show variations in length and thickness with respect to the orientation, the geometry and distribution of melt pockets in 3D are poorly constrained. Here, we use an improved statistical model to identify the dependence of melt pocket dimensions as functions of orientation. We further calculate melt flux through individual melt streaks and estimate permeability corresponding to the observed melt distribution texture. We found that deformation in the mantle can significantly accelerate melt extraction and potentially bend the melt flow using anisotropic permeability. Key Points We parameterized the 3D shapes and orientations of melt pockets under the constraints of observed melt‐preferred orientation (MPO) Permeability in peridotites deformed under vertical compression increases with compressive strain and demonstrates anisotropy up to two Permeability in peridotites deformed under simple shear demonstrates anisotropy of at least three
Repacking Accelerates High‐Silica Melts Extraction: Insights From Microstructural Record and Numerical Modeling
Repacking enhances crystal mush permeability, accelerating melt extraction. However, identifying microstructural records of repacking is challenging, creating a gap in quantifying its effect on magmatic reservoirs. We identified extracted melt (rhyolite) and silicic residue (quartz monzonite) through textures and geochemical characteristics in the Pangduo Basin (Southern Tibet; ∼50 Ma old). By calculating interstitial mineral proportions and modeling incompatible element concentrations in quartz monzonite, we estimate a moderate trapped melt fraction (∼50 vol. %), providing microtextural evidence of repacking at intermediate crystallinities. We interpret that the horizontal preferred orientation of frame‐forming feldspars produces micro‐scale melt channels that accelerate melt extraction. Modeling the intensity of this orientation, we estimated compressive strain to be 20%–30%, likely accelerating melt extraction by at least 15 times. This millennium timescale allows for the growth of a large magma chamber, preventing the melt from freezing or causing multiple small eruptions due to excessive flow‐induced stress. Plain Language Summary Explosive rhyolite eruptions significantly affect climate, the environment, and human life. These devastating events, involving crystal‐melt separation in large upper crustal magma reservoirs, may be accelerated by grain reorganization. Yet, quantifying this acceleration is complex. Our study utilizes samples from the Pangduo Basin in southern Tibet to examine the pertinent microstructure and calculate the acceleration rate of crystal‐melt separation. We found that grain reorganization can reduce the separation duration by a factor of 15, highlighting its critical role in crystal‐melt separation. Key Points The rhyolite and quartz monzonite of the Pangduo Basin represent extracted melt and corresponding residual cumulates, respectively Interstitial minerals fraction and mass‐balance calculations yield a moderate trapped melt fraction of ∼50 vol. % The horizontal preferred orientation of large‐grained feldspars accelerates melt extraction by at least 15 times
Synthetic microbial community in pristine environment promotes the growth of the endangered plant Lilium tsingtauense
Background Habitat fragmentation and degradation have led to the critical endangerment of numerous wild plant species. Although significant achievements in the conservation of endangered wild plants in various regions worldwide, the interaction mechanisms between these plants and their associated rhizosphere microorganisms have yet to be fully elucidated. Results Here, we present a communication model between the endangered wild plant Qingdao lily ( Lilium tsingtauense ) and its associated rhizosphere microorganisms. We isolated a rhizosphere fungus, Trichoderma longibrachiatum QDAU 0920, which effectively colonizes the roots of Qingdao lily and significantly promotes root growth. This growth enhancement is mediated by multiple plant hormones, with auxin playing a particularly prominent role. Further investigation revealed that a non-canonical AUX/IAA protein of the LtIAA16 may augment the transcriptional activation activity of LtARF22 by competitively interacting with LtIAA6, LtIAA17, and LtIAA11, thereby facilitating root growth in Qingdao lily. The growth-promoting effects of this interaction were subsequently validated in several other plant species, including tomato, pepper, corn, pumpkin, and cucumber. Notably, T. longibrachiatum QDAU 0920 forms synthetic microbial consortia (SynComs) in conjunction with other Trichoderma and Penicillium species. These SynComs consistently enhance the growth of Qingdao lily as well as other lily species such as L. lancifolium , Lilium 'Avalon Sunset', and Lilium 'Deliana'. Conclusion Collectively, these findings underscore the considerable potential of native microorganisms in the development of plant growth-promoting agents and the conservation of endangered plant species. 3z6G1p56xUe8HzgozDGL2y Video Abstract
IFC-Based 4D Construction Management Information Model of Prefabricated Buildings and Its Application in Graph Database
Effective data interoperability and schedule analysis play a significant role in improving the management of prefabricated buildings. However, there is a lack of efficient strategies and comprehensive approaches for data interoperability and data-based automated schedule analysis. This paper intends to promote prefabricated buildings’ management by solving these two problems via developing an IFC-based framework consisting of three parts. Firstly, this framework proposed a mechanism to establish an IFC-based 4D construction management information model of prefabricated buildings. Furthermore, a non-relational database—graph database—is introduced to twin this model into a task-centered network to realize the interoperation of construction information among different participants. Finally, graph database-based strategies to update data, automatically analyze construction schedules and visualize the 4D construction management information model are described. The proposed framework is validated in a prefabricated engineering case. In this case, an IFC-based and graph database-based 4D construction management information model is established through IFC standard’s extension. The graph database-based analysis of the model automatically recognizes the engineering case’s critical path information, delay analysis information, and schedule network analysis information. It is illustrated that this framework can successfully establish a unified IFC-based information model of prefabricated buildings’ construction management to prompt effective data interoperability. In addition, the application of this IFC-based information model in graph database can automatically analyze the construction schedules to prevent possible delays in advance. In short, the significance of this paper is to innovatively propose an IFC-based and graph data-based information model to solve the difficulties of ineffective data interoperation and unautomated schedule analysis in prefabricated buildings’ construction management. This study can be the digital foundation of further IFC-based digital twin.
RcMYB8 enhances salt and drought tolerance in rose (Rosa chinensis) by modulating RcPR5/1 and RcP5CS1
Plant Myeloblastosis (MYB) proteins function crucially roles upon variegated abiotic stresses. Nonetheless, their effects and mechanisms in rose ( Rosa chinensis ) are not fully clarified. In this study, we characterized the effects of rose RcMYB8 under salt and drought tolerances. For induction of the RcMYB8 expression, NaCl and drought stress treatment were adopted. Rose plants overexpressing RcMYB8 displayed enhanced tolerance to salinity and drought stress, while silencing RcMYB8 resulted in decreased tolerance, as evidenced by lowered intra-leaf electrolyte leakage and callose deposition, as well as photosynthetic sustainment under stressed conditions. Here, we further show that RcMYB8 binds similarly to the promoters of RcPR5/1 and RcP5C51 in vivo and in vitro. Inhibiting RcP5CS1 by virus-induced gene silencing led to decreased drought tolerance through the reactive oxygen species (ROS) homeostatic regulation. RcP5CS1- silenced plants showed an increase in ion leakage and reduce of proline content, together with the content of malondialdehyde (MDA) increased, lowered activities of Catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD). Our study highlights the transcriptional modulator role of RcMYB8 in drought and salinity tolerances, which bridges RcPR5/1 and RcP5CS1 by promoting ROS scavenging. Besides, it is probably applicable to the rose plant engineering for enhancing their abiotic stress tolerances. Graphical Abstract
Experimental investigation on the effects of temperature and w/c on corrosion characteristics of rebars in concrete exposed to salt lake environments
The high-salinity environments in salt lakes can significantly affect the durability of reinforced concrete. However, there needs to be more reports on the corrosion characteristics of the rebars under salt lake environments, which play a crucial role in studying the deterioration of concrete structures. This study meticulously investigated how temperature variations and changes in water-cement ratios affect the corrosion of rebars in high-salinity lake water conditions, which not only supplements the existing research gap in salt lake conditions but also offers insights for predicting the service life of concrete structures under such circumstances. Reinforced concrete specimens with water-cement ratios of 0.49, 0.54, and 0.60 were tested in both the atmospheric zone and dry–wet cycling zone at temperatures of 15 °C, 30 °C, 35 °C, and 40 °C. A three-electrode system was utilized to monitor the corrosion potentials of the rebars, while the linear polarization method was employed to determine the polarization resistance. The time to corrosion initiation, threshold chloride concentration, and corrosion current density were determined and discussed. The results indicated that temperature and salinity did not significantly affect the corrosion potentials of rebars. However, corrosion initiation occurred much faster under salt lakes than in marine environments, with initiation times averaging around 100 days. Furthermore, it was found that the corrosion rate tended to increase as the temperature and water-cement ratio increased. Additionally, the rebars in the atmospheric zone exhibited lower threshold chloride concentration than those in the dry–wet cycling zone at temperatures of 30 °C, 35 °C, and 40 °C, and higher temperatures corresponded to more significant differences in threshold chloride concentration between the two zones. Lower water-cement ratios were shown to delay corrosion initiation and increase the threshold chloride concentration, suggesting the effectiveness in mitigating rebar corrosion in high-salinity environments. Graphical Abstract
What can we learn from REE abundances in clinopyroxene and orthopyroxene in residual mantle peridotites?
Clinopyroxene and orthopyroxene are the two major repositories of rare-earth elements (REE) in spinel peridotites. Most geochemical studies of REE in mantle samples focus on clinopyroxene. Recent advances in in situ trace element analysis have made it possible to measure REE abundance in orthopyroxene. The purpose of this study is to determine what additional information one can learn about mantle processes from REE abundances in orthopyroxene coexisting with clinopyroxene in residual spinel peridotites. To address this question, we select a group of spinel peridotite xenoliths (9 samples) and a group of abyssal peridotites (12 samples) that are considered residues of mantle melting and that have major element and REE compositions in the two pyroxenes reported in the literature. We use a disequilibrium double-porosity melting model and the Markov chain Monte Carlo method to invert melting parameters from REE abundance in the bulk sample. We then use a subsolidus reequilibration model to calculate REE redistribution between clinopyroxene and orthopyroxene at the extent of melting inferred from the bulk REE data and at the closure temperature of REE in the two pyroxenes. We compare the calculated results with those observed in clinopyroxene and orthopyroxene in the selected peridotitic samples. Results from our two-step melting followed by subsolidus reequilibration modeling show that it is more reliable to deduce melting parameters from REE abundance in the bulk peridotite than in clinopyroxene. We do not recommend the use of REE in clinopyroxene alone to infer the degree of melting experienced by the mantle xenolith. In general, HREE in clinopyroxene and LREE in orthopyroxene are more susceptible to subsolidus redistribution. The extent of redistribution depends on the modes of clinopyroxene and orthopyroxene in the sample and thermal history experienced by the peridotite. By modeling subsolidus redistribution of REE between orthopyroxene and clinopyroxene after melting, we show that it is possible to discriminate mineral mode of the starting mantle and cooling rate experienced by the peridotitic sample. We conclude that endmembers of the depleted MORB mantle and the primitive mantle are not homogeneous in mineral mode. A modally heterogeneous peridotitic starting mantle provides a simple explanation for the large variations of mineral mode observed in mantle xenoliths and abyssal peridotites. Finally, using different starting mantle compositions in our simulations, we show that composition of the primitive mantle is more suitable for modeling REE depletion in cratonic mantle xenoliths than the composition of the depleted MORB mantle.
Preparation and Properties of Multilayer Ca/P Bio-Ceramic Coating by Laser Cladding
In order to enhance the bioactivity and wear resistance of titanium (Ti) and its alloy for use as an implant surface, a multilayer Ca/P (calcium/phosphorus) bio-ceramic coating on a Ti6Al4V alloy surface was designed and prepared by a laser cladding technique, using the mixture of hydroxyapatite (HA) powder and Ti powder as a cladding precursor. The main cladding process parameters were 400 W laser power, 3 mm/s scanning speed, 2 mm spot diameter and 30% lapping rate. When the Ca/P ceramic coating was immersed in simulated body fluid (SBF), ion exchange occurred between the coating and the immersion solution, and hydroxyapatite (HA) was induced and deposited on its surface, which indicated that the Ca/P bio-ceramic coating had good bioactivity. The volume wear of Ca/P ceramic coating was reduced by 43.2% compared with that of Ti6Al4V alloy by the pin-disc wear test, which indicated that the Ca/P bio-ceramic coating had better wear resistance.