Fast Construction Research Articles

Mild and Fast Construction of Ni-Based Electrodes for Industrial-Grade Water Splitting

Achieving high−efficiency and stable hydrogen evolution from water splitting is a great challenge. Herein, a facilely prepared two−dimenssional self−supported catalytic electrode with excellent stability is constructed for large−scale hydrogen production from alkaline simulated seawater. The bifunctional catalytic electrode is prepared by a fast and mild one−step of sodium borohydride etching on a nickel foam (NF) substrate without adding other additives (NF@NiBx−3h). The overpotential of the hydrogen/oxygen evolution reaction (HER/OER) in alkaline−simulated seawater at 10 mA cm−2 is 96 mV and 261 mV. At 200 mA cm−2, the NF@NiBx−3h electrode shows good stability over 7 days throughout the water splitting process due to the corrosion resistance of the NF substrate, and strong adhesion between the Ni−B active material and the substrate. This work demonstrates a novel strategy for fabricating catalytic electrodes with high−performance, low cost and excellent stability.

Re-Design of the Structure of the Batang I Industrial Flats Worker Building Using the Precast Concrete Method

The Industrial Workers' Flats, located in the Batang Integrated Industrial Area, are supporting facilities workers use. The building was previously planned using conventional methods. In many cases, demands for fast and efficient construction work often occur, especially in the case of high-rise buildings. The need for multi-storey buildings encourages the need for an economical structural design that can be implemented quickly and efficiently without reducing the stiffness between the components of the building structure. From the explanation above, it is re-planned using the precast concrete method so that the work is neat, precise, and fast. In this planning, the SRPMK system is used. It needs good supervision in precast concrete, especially in joints, because precast joints are not as monolithic as conventional ones. It is necessary to develop precast technology to be more innovative in its use and easier to apply.

Processing of weather radar raw IQ-data towards the identification and correction of wind turbine interference – Project RIWER: Removing the Influence of Wind Park Echoes in Weather Radar Measurements

Abstract. In recent years, the fast construction, expansion and repowering of wind parks have been a major source of concern for the weather radar community and meteorological services. Among others because wind turbines are extremely tall, reflective, and moving objects, which make them a source of interference that is hard to distinguish from meteorological echoes and therefore difficult to filter and even more difficult to correct. Polarimetric C-Band Doppler weather radar measurements enable us to analyse and understand the impact of wind turbine interference on meteorological weather radar echoes and to build up knowledge. The main idea is to analyse the raw IQ-data in order to quantify the behaviour of wind turbine interference with meteorological scattering. As a first step in this direction, this paper will focus on the derivation and analysis of radar moments such as Reflectivity (Z), Differential Reflectivity (ZDR), Differential Propagation Phase (PHIDP), Mean Doppler Velocity (V), and Correlation Coefficient (RHOHV). We will consider two cases: (i) events with precipitation, and (ii) events without precipitation, in order to understand and model the impact of wind turbine interference (WTI). For this purpose, weather radar measurements from Deutscher Wetterdienst (DWD), recorded under the aegis of the project RIWER (Removing the Influence of Wind Park Echoes in Weather Radar Measurements), are presented, analysed and discussed in detail.

Research on multi-Unmanned aerial vehicle joint delivery mission assignment based on multiple Alliance

In order to improve the battlefield delivery ability, for the battlefield joint delivery process task is heavy, time, traditional iron, public, water and other vulnerable to terrain, transportation conditions lead to low delivery efficiency, large-scale delivery mission capacity, the paper considers to use drones joint delivery task, according to the problem, summarize inspired rules, design fast construction model algorithm, using dynamic comprehensive sorting method, improve the task allocation and delivery efficiency, provide a reference for enriching the military diversified delivery mode, and improve the air delivery ability.

Solution-based tabu search for the capacitated dispersion problem

Given a weighted graph with a capacity associated to each node (element), the capacitated dispersion problem (CDP) consists in selecting a subset of elements satisfying a capacity constraint, in such a way that the minimum distance among them is maximized. The purpose of this work is to tackle this NP-hard problem, by developing an effective and parameter-free heuristic algorithm based on the solution-based tabu search. Specifically, we propose a fast greedy construction heuristic to obtain high-quality initial solutions. To ensure a high search efficiency, our algorithm exploits the combination of three neighborhoods, including a new neighborhood based on the constrained swap strategy, and uses hash functions to identify eligible candidate solutions. Extensive computational experiments on benchmark instances in the literature are performed to demonstrate the high performance of our algorithm and get insights into the influences of the algorithmic components. The application of our algorithm to a realistic location problem further shows the usefulness of our approach for practical problems.

Algorithms for the extension two-dimensional fuzzy signal via decomposition and reconstruction in fuzzy wavelets

he decomposition of an image can be done in the following way: The image is split into a low-resolution part, which can be described by a smaller number of samples than the original image, and a signal difference, which describes the difference between the low-resolution image and the real coded image. Therefore, this low-resolution image is also decomposed into a low-resolution image and a difference image, making more efficient coding possible. This decomposition is repeated several times, so that a hierarchical image decomposition is created. Thus, the low-resolution image is only half the size of the original image. This reduced image is enlarged to the size of the original image. The result is a detailed image that is the same size as the original image. Our problem is: "Can we build algorithms allowing the decomposition and reconstruction of a signal in a fuzzy environment? We will answer in the affirmative. This construction is first made possible by one-dimensional fuzzy multiresolution analysis, which will later be extended to two dimensions. In the first part, we recall some definitions and main results obtained on the existence of fuzzy multiresolution analysis in the one-dimensional case, for the decomposition of a fuzzy image. The second part, based on this multi-resolution analysis, presents a fast construction algorithm for the analysis and synthesis of a fuzzy signal. Finally, the third part is nothing else than an extension of this algorithm to 2 dimensions, by the fuzzy multiresolution two-dimensional analysis

Analysis of 5G Smart Communication Base Station Doppler-Smoothed Pseudorange Single-Point Geodesic Positioning Accuracy

With the continuous development of mobile communication and satellite navigation technologies, the positioning requirements of 5G smart communication base stations are becoming higher and higher. With the opening of GNSS raw observation data, research on the positioning of a 5G smart communication base station has become a research hotspot in the surveying and mapping disciplines. In this paper, based on the GNSS observation data of the 5G smart communication base station, the quality of the original GNSS observation data of the 5G smart communication base station is studied and analyzed. A method based on Doppler smoothing pseudorange solves the problem that the original pseudorange observation values of the 5G smart communication base station are noisy and prone to multipath errors due to the limitations of the base station chips and processes, which makes the traditional data processing methods unable to meet the demand for higher accuracy positioning. This method uses Doppler observations to smooth the pseudorange and determines the Doppler smoothing strategy and closure values to improve the data quality. The experimental data show that Doppler smoothing pseudorange can improve data quality and positioning accuracy by 67.9% in the E direction, 64.8% in the N direction, and 65.5% in the U direction. The future world will develop in the direction of intelligence, and the wireless network 5G technology used to support the construction of this intelligent system will become the core driver for the development of a leading intelligent society. 5G network signals have higher reliability and lower latency and can meet the specific needs of smart manufacturing, autonomous driving, and other industrial applications. This new base station product can meet the construction needs of future 5G base stations, adapt to the future intensive, miniaturized, intelligent station construction mode, and realize safe and fast station construction, providing the necessary hardware support for 5G network coverage.

3C-3D tunnel seismic reverse time migration imaging: A case study of Pearl River Delta Water Resources Allocation Project

In recent years, tunnel boring machines (TBMs) have been widely used because of their fast construction speed and economical benefits, and the need to obtain geological information ahead of the tunnel to ensure the TBM tunnel construction safety has also arisen. Faced with the complex geological environment, seismic forward-prospecting is the primary method for predicting the unfavorable geological structure in front of the tunnel face. As a crucial step in seismic forward-prospecting method, migration can image geological characteristics and help learn the distribution of unfavorable geology. To achieve all-round imaging of unfavorable geology, we suggested a three-component (3C) three-dimensional (3D) tunnel seismic reverse time migration imaging method. The acoustic wave equation is employed for the forward and backward wavefield extrapolation after the P/S-wave separation to eliminate the imaging artifacts from severe converted waves in tunnels. GPU parallelization is used to accelerate the calculation to further adapt to the rapid excavation of TBMs. The proposed method is validated in two typical numerical models, especially for 3C seismic data that provides all-round geological information to achieve enhanced imaging energy and artifact reduction, which demonstrates the significance of 3C seismic data to migration imaging. This case study was conducted in the Pearl River Delta Water Resources Allocation Project in Guangdong Province, China. The reliability of 3C3D tunnel seismic reverse time migration imaging in field tunnel engineering was investigated. Two consecutive detections were performed, and then the spatial positions of faults and fractures in front of the tunnel face were accurately judged by the combination of the two imaging results. Based on the detection results, the excavation rate was slowed down and the tunnel lining support was increased. The TBM then successfully passed through the risk areas. This case study can serve as a reference for other tunnels with similar concerns regarding the necessity of 3C seismic data and consecutive detections.

Construction of hydrophobic-hydrophilic microfluidic patterns with controlled wettability on PVDF filter paper surface using maskless microplasma scanning

Paper-based microfluidic analytical devices (μPADs) have attracted increasing interest due to their unique advantages. Localized hydrophilization on hydrophobic paper surfaces to form the microfluidic patterns and their wettability control are the key issues in μPADs preparation. This paper introduces a novel method to construct hydrophobic-hydrophilic microfluidic patterns on the surface of the Poly(vinylidene fluoride) (PVDF) filter paper by maskless microplasma writing. The hydrophilic performances and surface morphology of the patterns were characterized by water contact angle (WCA) and scanning electron microscopy (SEM). Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) were used to analyze their chemical compositions. The results showed that paper surface changed from hydrophobic to hydrophilic and its wettability can be controlled through plasma parameters adjustment. PVDF layer was gradually removed from the filter paper and the fluorine-containing groups on paper surface of the micropatterns decreased with increasing microplasma treatment time. Besides, the polar functional groups (e.g. –C=O) also appeared and increased with longer treatment time. Finally, the mechanism of the microfluidic patterns construction by microplasma was discussed, and the microfluidic pattern with the pattern “H” were demonstrated and successfully constructed. This work shows great potential for simple, fast, environmental friendly and low-cost construction of μPADs.

Prefabricated Volumetric Modular Construction: A Review on Current Systems, Challenges, and Future Prospects

Rapid urbanization and population growth worldwide has stimulated the requirement of fast and efficient construction techniques. An emerging trend in the construction industry focuses on prefabricated volumetric modular construction (PVMC), wherein individual room size prefabricated modules are manufactured off-site and transported to the site for assemblage using joint connections. This paper provides a comprehensive review on prefabricated modular structural systems, general concepts, joint connections for steel and concrete modules, and their structural behavior. Further, the impediments in current PVMC systems are outlined and technical challenges that restrict the widespread acceptance of PVMC systems are discussed. PVMC is advantageous over conventional construction with regard to construction efficiency, material optimization, speed, safety, and quality control, along with reduced environmental impact. However, application of PVMC in construction industry is very limited due to lack of sufficient understanding on joint connections, seismic behavior, and design methods. It is inferred that reasonable research has been carried out to study the behavior of connection systems at the local level, while research on global seismic performance of prefabricated modular buildings is scarce, which calls for extensive experimental investigations on full-scale modular buildings subjected to lateral loading.

NPS COMPOSITE BEAMS AND COLUMNS USED FOR THE ODENSE UNIVERSITY HOSPITAL

AbstractThis document presents the case study of the Odense University Hospital, built with the NPS steel‐concrete composite frame. This is one of the most challenging projects currently in Europe: 250,000 square meters to be built in just over three years. The client has taken up the challenge of respecting timeframe and budget by focusing on offsite construction and digitalization of processes. Time constrains, safety and sustainability are the three main drivers of the project. Among these, the strict delivery time represents the main critical aspect. The expected turnkey delivery in 2022 assumed the choice of an extremely simple and fast construction method. Further advantages of using steel‐concrete composite structures with reference to the Odense University Hospital Case are explained.

Hydrodynamic Characteristics of Three-Bucket Jacket Foundation for Offshore Wind Turbines During the Lowering Process

The three-bucket jacket foundation is a new type of foundation for offshore wind turbine that has the advantages of fast construction speed and suitability for deep water. The study of the hoisting and launching process is of great significance to ensure construction safety in actual projects. In this paper, a new launching technology is proposed that is based on the foundation of the three-bucket jacket for offshore wind turbine. A complete time domain simulation of the launching process of three-bucket jacket foundation is carried out by a theoretical analysis combined with hydrodynamic software Moses. At the same time, the effects of different initial air storage and sea conditions on the motion response of the structure and the hoisting cable tension are studied. The results show that the motion response of the structure is the highest when it is lowered to 1.5 times the bucket height. The natural period of each degree of freedom of the structure increases with the increase of the lowering depth. The structural motion response and the hoisting cable tension vary greatly in the early phases of Stages I and III, smaller in Stage II, and gradually stabilize in the middle and late phases of Stage III.

Nonlinear Analysis of External Post-Tensioning anchorage of Concrete Segment

Abstract: Precast concrete segmental bridges (PCSBs) have been the most common design technology used in the last decades. In these studies Non-linear structural performances of externally prestressed, precast concrete segmental bridges (PCSB). PCSBs with externally prestressed tendons have become very popular in construction because of economical and safety reasons, fast and practical construction, and outstanding serviceability. External tendons technique is widely used because it allows to inspect the cables and to replace them or to reinforce the tendons in case of damage while such kinds of actions are difficult to be taken in case of internal prestressing. It is widely recognized that segmental bridges have better durability, lower life-cycle costs and higher quality for maintenance than other types of bridges. However, there is lack of reliable computational model for analyzing behavior of post-tensioned PCSBs. Experimental analysis of bridge segment required more cost, time and effort for the analysis and also take cake of quality of material, cast process, curing, and testing. This research presents the results of stress and strain state of the local bearing area caused by a Prestressed cable anchor in reinforced concrete bridge segment. Nonlinear analysis of anchorage and rebar, concrete segment can be carried out by analytical solution calculated with the reference of ACI 318/19. ANSYS software is used for model and analyze the structure. The analysis process was carried out in 3 types : linear elastic analysis, nonlinear elastic analysis, and nonlinear analysis considering the destruction of concrete, and the value is compared with ANSYS software ( static structure).

Lane-specific speed analysis in urban work zones with computer vision

Objective Work zone speed is one of the most important factors in road construction safety management. This work presents a computer vision based technique designed to measure lane-specific individual vehicle speed using existing traffic monitoring cameras and computers. The resulted speeds support the influence analysis of factors including traffic control, lane positions, and construction activity. Methods Object detection (YOLOv5) and tracking (Deep-SORT) algorithms are combined to track the vehicles. In particular, 21 days’ worth of road construction videos are collected from a pole-mounted traffic monitoring camera operated by the Texas A&M University Transportation Services. Based on the object detection results, a novel construction activity inference technique is developed to approximate the times when construction workers are present. Based on this time separation, the vehicle speeds with and without the presence of construction activity are compared. Results The proposed framework is able to measure speeds with an error ranging from 0 to 6.4 kilometers per hour (KPH). Detailed analysis of this video data suggests that traffic control with barrels in the median work zone lowers the average speed (for all vehicles) by 15 KPH. The lane adjacent to the work zone also has higher speed variation than the other lanes. The construction activity speed comparisons show when the traffic is slow (possibly traffic after a red light), the difference is statistically significant with a p-value ranging from 0.01 to 0.03. When the traffic is fast (possibly traffic encountering a green signal as they approached the nearby intersection) construction activity has no significant effect on the work zone speeds. Conclusions The proposed CV technique is a reliable and cheap method to measure lane-specific work zone speeds. The derived measurements support detailed safety analysis. Other than work zone speeds, the proposed technique can also be used for regular traffic speed monitoring.

Enantioselective C(sp3)–C(sp3) Reductive Cross-Electrophile Coupling of Unactivated Alkyl Halides with α-Chloroboronates via Dual Nickel/Photoredox Catalysis

Substantial advances in enantioconvergent C(sp3)-C(sp3) bond formations have been made with nickel-catalyzed cross-coupling of racemic alkyl electrophiles with organometallic reagents or nickel-hydride-catalyzed hydrocarbonation of alkenes. Herein, we report an unprecedented enantioselective C(sp3)-C(sp3) reductive cross-coupling by the direct utilization of two different alkyl halides with dual nickel/photoredox catalysis system. This highly selective coupling of racemic α-chloroboronates and unactivated alkyl iodides furnishes chiral secondary alkyl boronic esters, which serve as useful and important intermediates in the realm of organic synthesis and enable a desirable protocol to fast construction of enantioenriched complex molecules.

FIImap: Fast Incremental Inflate Mapping for Autonomous MAV Navigation

Three-dimensional mapping is an essential component of autonomous Micro Aerial Vehicle (MAV) navigation. The paper focuses on the 3D spatial representation method of MAV to overcome the collision problem caused by soft constraints, control error, and planning with the center of mass by inflating the occupancy grid map. A fast incremental inflated map construction method is proposed, which reduces the time-consumption caused by the increase of map range and inflated size. The method focuses on areas of the map that occupied state changes and introduces two arrays that record newly appearing and disappearing obstacles. Then, a series of breadth-first search algorithms are used to traverse the parts of the inflated map that need local modification to update the inflated map. Moreover, a sliding map model is designed based on the MAV position, which is suitable for large-range autonomous flight. The effectiveness of the proposed approach is verified with simulated and actual flight data. The proposed method takes about 3 ms to construct the inflated map with a local update range of 16 m × 16 m × 6 m.

Regiospecificity C(sp2)-C(sp3) Bond Construction between Purines and Alkenes to Synthesize C6-Alkylpurines and Purine Nucleosides Using O2 as the Oxidant.

A highly site-selective and Markovnikov-type radical C6-H alkylation of purines with alkenes is achieved, allowing fast construction of the C(sp2)-C(sp3) bond at the C-6-position of purines and purine nucleosides using O2 as a green oxidant and alkenes as cheap alkylation reagents. The route was also a radical route to synthesize C6-alkyl-N7-substituted purines with potential steric hindrance between C6-alkyl groups and N7-substituted groups. This reaction is easily scaled up and has excellent functional group compatibility and broad substrate scopes. Moreover, the unstable intermediate was also separated, which was the key evidence for the reaction mechanism.

Resisting spread of environmental-pollution diseases due to Portland-cement industries: green nanoclay applications

New eco-friendly thermal-casting ductile CPNC-concrete and CPNC-mortar materials have been developed without Portland-cement or water-use. It needs three hours for thermal synthesis. It contains 5%, 10% or 15% green natural nanoclay–polymer nanocomposite CPNC as a bonding-agent instead of Portland-cement for mixing with sand and crushed-stones by heating at 250 °C in electric ovens. CPNC is a dry powder consisting of 5% montmorillonite (MMT) nanoclay and 95% high-density polyethylene (HDPE). The study includes mixing, thermal synthesis, mechanical, fracture, and ductility property testing, and characterizations of the chemical composition, microstructure morphology and homogeneity using EDAX, SEM and XRD. It has new properties, such as a homogenous-microstructure with bonding, self-compaction abilities, no-cracks, ductility, good compressive and tensile strengths, and good fracture properties. It does not exhibit steel corrosion; it has rapid processing, no-water curing, low-density, no-shrinkage cracks, no-sudden failure, no-pollution utilizing a new manufacturing technique. CPNC-concrete is developed to stop the Portland-cement industry problems, to produce a clean and green environment without Portland-cement damage for human beings and to conserve drinking water. It has potential for different applications in construction, and it is suitable for 3D techniques with fast construction. Furthermore, this material requires new special codes for design and construction.

Heat Transfer Characteristics of Modular Heat Storage Wall Solar Greenhouse Based on Active Heat Storage System

The modular heat storage wall is a new type of solar greenhouse wall structure, which has the advantages of fast construction and good heat storage ability. This study provides data reference and practical value for producing modular heat storage wall in the construction of a solar greenhouse. In this paper, we used different heat storage materials to construct the modular wall. In the winter thermal environment test, soil module solar greenhouse (SG) and stone module solar greenhouse (PG) were controlled against each other in two greenhouses. The test results for 28 consecutive days (31 January 2021 9:00 to 28 February 2021 9:00) showed that both greenhouses could effectively increase the temperature in greenhouse by 10–12 °C. The average temperature of SG was 0.86 °C lower than that of PG during the daytime (09:00–17:00) and 0.44 °C higher than that of PG during the nighttime (17:00–09:00). Under typical sunny conditions, the average temperature differences between the inlet and outlet of SG in the heat storage and exothermic stage was less than that of PG, and the relative humidity difference was greater than that of PG. This indicated that SG had a better performance of heat preservation than PG and could raise the nighttime temperature rapidly. Under the condition of a typical cloudy day, the average temperature difference between the inlet and outlet was SG < PG and the relative humidity difference was SG > PG in the exothermic stage, which was consistent with the conclusion of sunny days. In the storage and exothermic stages of typical sunny days and cloudy days, the total heat exchange of SG was 464.87, 110.44 and 54.82 MJ and the total heat exchange of PG was 264.16, 61.60 and 46.89 MJ, respectively. Moreover, the heat storage and release of SG were more than that of PG in all stages. In summary, the thermal performance of the modular heat storage wall heliogreenhouse could meet the growth of tomato crop, in which the heat transfer performance of SG was optimum.

A novel steel bulkhead based on the method of prefabrication and assembly and its first application to the Yuliangzhou immersed tunnel

Temporary bulkheads installed at the end of each tunnel element are indispensable for immersed tunnel elements to be watertight and float. Currently, welded steel bulkheads and cast-in-place concrete bulkheads have been applied in the installation of most immersed tunnels; however, these bulkheads have many inherent drawbacks. For example, existing cast-in-place concrete bulkheads are bulky and cannot be recycled after demolition. In addition, existing welded steel bulkheads, which cannot be fully reused, are installed and dismantled with a large number of on-site welding operations. Relying on the Yuliangzhou Immersed Tunnel in China, a novel steel bulkhead based on the method of prefabrication and assembly, namely, a piece-assembled steel bulkhead, was developed to address the abovementioned problems. The structural components of the new steel bulkhead applied to realize full recycling mainly include steel bulkhead panels, ethylene-propylene-diene-monomer (EPDM) sealing gaskets, steel bearings, and steel connecting bolts. The water tightness function of the new bulkhead was achieved through the compression deformation of the designed EPDM sealing gaskets inside the assembly seams, which were designed as multihole structures to save manufacturing material. Nonlinear finite element simulations were conducted to investigate the gasketed seam mechanical and sealant behavior. It was concluded that the control threshold value of gasketed seam compression displacement needed to satisfy the design requirement for a 250 kPa waterproof capacity could be taken as 15 mm, while that for seam offset displacement was set to 40 mm. To achieve the fast and efficient construction of the new steel bulkhead, a strategy of symmetrically installing and removing steel bulkhead panels piece by piece at one carriageway bore was proposed, and an automatic installation trolley that adjusts the bulkhead panel position in three directions was designed and developed. Finally, the on-site monitoring of the assembly seam displacements and the stress and deformation of the H-shaped steel beam verified that the new steel bulkhead was in a safe state and displayed good watertightness. This bulkhead was successfully applied in the Yuliangzhou Immersed Tunnel project, and this test application supports the use of these technologies in immersed tunnel construction.