Lunar In Situ Large-Scale Construction:Quantitative Evaluation of Regolith Solidification Techniques

Lunar habitat construction is crucial for successful lunar exploration missions.Due to the limitations of transportation conditions,extensive global research has been conducted on lunar in situ material processing techniques in recent years.The aim of this paper is to provide a comprehensive review,precise classification,and quantitative evaluation of these approaches,focusing specifically on four main approaches:reaction solidification(RS),sintering/melting(SM),bonding solidification(BS),and confinement formation(CF).Eight key indicators have been identified for the construction of low-cost and highperformance systems to assess the feasibility of these methods:in situ material ratio,curing temperature,curing time,implementation conditions,compressive strength,tensile strength,curing dimensions,and environmental adaptability.The scoring thresholds are determined by comparing the construction requirements with the actual capabilities.Among the evaluated methods,regolith bagging has emerged as a promising option due to its high in situ material ratio,low time requirement,lack of hightemperature requirements,and minimal shortcomings,with only the compressive strength falling below the neutral score.The compressive strength still maintains a value of 2–3 MPa.The proposed construction scheme utilizing regolith bags offers numerous advantages,including rapid and large-scale construction,ensured tensile strength,and reduced reliance on equipment and energy.In this study,guidelines for evaluating regolith solidification techniques are provided,and directions for improvement are offered.The proposed lunar habitat design based on regolith bags is a practical reference for future research.

Construction Method for Performance Management Curriculum Content System Based on Knowledge Graph

Performance Management is the core course of human resource management major,but its knowledge points lack multi-dimensional correlations.There are problems such as scattered content and unclear system,and it is urgent to reconstruct the content system of the course.Knowledge graph technology can integrate massive and scattered information into an organic structure through semantic correlation and reasoning.The application of knowledge graph to education and teaching can promote scientific and personalized teaching evaluation and better realize individualized teaching.This paper systematically combs the knowledge points of Performance Management course and forms a comprehensive knowledge graph.The knowledge point is associated with specific questions to form the problem map of the course,and then the knowledge point is further associated with the ability target to form the ability map of the course.Then,the knowledge point is associated with teaching materials,question bank and expansion resources to form a systematic teaching database,thereby giving the method of building the content system of Performance Management course based on the knowledge map.This research can be further extended to other core management courses to realize the deep integration of knowledge graph and teaching.

Study on the Impact of Collective Commercial Construction Land Entering the Market on Rural Residents’Income:Taking Deqing County,Zhejiang Province as an Example

The entry of collective construction land for business purposes is an important measure for deepening the reform of the rural land system,promoting the flow of urban and rural factors,and realizing rural revitalization.Since the production of the first batch of pilot projects in 2015,33 county-level cities have participated in the pilot policy by 2023.Deqing County,Zhejiang Province,as the first area to participate in the pilot project,aims to achieve more fruitful results.This paper first examines how promoting farmers’income through the market entry of agricultural land can be achieved,then uses the synthetic control method to quantitatively study the impact of collective operational construction land on farmers’income using panel data from 2011 to 2019,and finally proposes relevant suggestions from the perspective of system reform.

Comparison of Construction Method for DEM Simulation of Ellipsoidal Particles

Discrete element model was developed to simulate the ellipsoidal particles moving in the moving bed. Multi-element model was used to describe a ellipsoidal particle, the contact detection algorithm of ellipsoidal particle was developed, and both contact force and gravity force were considered in the models. The simulation results were validated by our experiment. Three algorithms for representing an ellipsoidal particle were compared in macro and micro aspects. The results show that there exists big difference in the microscopic parameters such as kinetic energy, rotational kinetic energy, deformation, contact force and collision number which leads to the difference of macroscopic parameters. The relative error in the discharge rate and tracer particle position is the largest between 3-tangent-element representation and experimental results. The flow pattern is similar for the 5-element and 3-intersection representations. The only difference is the discharge rate of 5-element representation is larger than the experimental value and that of the 3-intersection representation has the contrary result. Finally the 3-intersection- element reoresentation is chosen in the simulation due to less comouting time than that of the 5-element renresentation.

Safety Risk Assessment of Overturning Construction of Towering Structure Based on Cloud Matter–Element Coupled Model

Rapid urbanization has led to a surge in the number of towering structures,and overturning is widely used because it can better accommodate the construction of shaped structures such as variable sections.The complexity of the construction process makes the construction risk have certain randomness,so this paper proposes a cloudbased coupled matter-element model to address the ambiguity and randomness in the safety risk assessment of overturning construction of towering structures.In the pretended model,the digital eigenvalues of the cloud model are used to replace the eigenvalues in the matter–element basic element,and calculate the cloud correlation of the risk assessment metrics through the correlation algorithm of the cloud model to build the computational model.Meanwhile,the improved hierarchical analysis method based on the cloud model is used to determine the weight of the index.The comprehensive evaluation scores of the evaluation event are then obtained through the weighted average method,and the safety risk level is determined accordingly.Through empirical analysis,(1)the improved hierarchical analysis method based on the cloud model can incorporate the data of multiple decisionmakers into the calculation formula to determine theweights,which makes the assessment resultsmore credible;(2)the evaluation results of the cloud-basedmatter-element coupledmodelmethod are basically consistent with those of the other two commonly used methods,and the confidence factor is less than 0.05,indicating that the cloudbased physical element coupled model method is reasonable and practical for towering structure overturning;(3)the cloud-based coupled element model method,which confirms the reliability of risk level by performing Spearman correlation on comprehensive assessment scores,can provide more comprehensive information of instances compared with other methods,and more comprehensively reflects the fuzzy uncertainty relationship between assessment indexes,which makes the assessment results more realistic,scientific and reliable.

Responses of bacterial community to potential heap construction methods of fine-grained copper tailings in column bioleaching system

The column bioleaching of copper flotation tailings was comparatively investigated using layered heap construction method(LM),agglomerate heap construction method(AM),and pellets-sintering heap construction method(PM).The bacterial communities of free,attached,weakly-attached,and strongly-attached microbes in the later bioleaching stage were investigated.In AM group,the addition of lump sulphide ore resulted in the low leachate pH,high ferric iron concentration,and rapid microbial adsorption,which obtained the maximum copper extraction(60.1%)compared with LM(54.6%)and PM(43.9%)groups.The relative abundance of dominant genera and microbial communities of different microbiota underwent changes in three heap construction methods.The alpha-diversity indexes of attached,weakly-attached,and strongly-attached microbes were different,while no significant change was observed in free bacteria.The variation of whole bacterial community was significantly associated with solution pH,total iron,and ferric iron concentrations.Pearson correlation analysis and partial least square path model both indicated that attached bacteria made larger contribution to the copper extraction of tailings.

Geometrical characteristic investigation of the Baihetan irregular columnar jointed basalt and corresponding numerical reconstruction method

Columnar jointed rock mass with unique geometric and geological properties is one spectacular example of geometrical order in nature.Columnar joints are generally accepted to be formed by spatially uniform volume contraction during cooling.In this paper,substantial field work was performed to study the geological characteristics of irregular columnar jointed basalt on the left bank dam foundation in the Baihetan Hydropower Station,where the columnar jointed rock mass is extensively exposed due to excavation.The quantitative measurements of the sizing of polygonal crack pattern of columnar joints and assessment of their degree of irregularity were summarized.Considering the irregularity of polygonal crack pattern,a modified Voronoi polygon(MVP)method was developed to model the special polygonal crack pattern of columnar joints.The new polygonal pattern obtained by the MVP method consists of a large number of irregular polygons,of which the degree of irregularity is consistent with the field measurement results.This method can reproduce the rapid evolution from an initial ideal regular hexagonal pattern to a final actual irregular polygonal pattern as the degree of irregularity increases.The compression tests of columnar jointed rock mass with different irregularity show that the geometric irregularity has a great influence on its mechanical properties.This numerical construction method provides a reliable way to reconstruct columnar joint structure with specific polygonal crack pattern,which is consistent with onsite columnar jointed basalt.

Inverse Construction Methods of Heterogeneous NURBS Object Based on Additive Manufacturing

According to the requirement of heterogeneous object modeling in additive manufacturing(AM),the Non-Uniform Rational B-Spline(NURBS)method has been applied to the digital representation of heterogeneous object in this paper.By putting forward the NURBS material data structure and establishing heterogeneous NURBS object model,the accurate mathematical unified representation of analytical and free heterogeneous objects have been realized.With the inverse modeling of heterogeneous NURBS objects,the geometry and material distribution can be better designed to meet the actual needs.Radical Basis Function(RBF)method based on global surface reconstruction and the tensor product surface interpolation method are combined to RBF-NURBS inverse construction method.The geometric and/or material information of regular mesh points is obtained by RBF interpolation of scattered data,and the heterogeneous NURBS surface or object model is obtained by tensor product interpolation.The examples have shown that the heterogeneous objects fitting to scattered data points can be generated effectively by the inverse construction methods in this paper and 3D CAD models for additive manufacturing can be provided.

Performance of the suspension method in large cross-section shallow-buried tunnels

Large cross-section tunnel construction induces ground surface settlements, potentially endangering both subterranean projects and nearby above-ground structures. A novel tunnel construction method, known as the suspension method,is introduced in this paper to mitigate surface settlement. The suspension method employs vertical tie rods to establish a structural connection between the initial tunnel support system and the surface steel beam, thereby exerting effective control settlements. To analyze the performance of the proposed method, systematic numerical simulations were conducted based on the practical engineering of Harbin Subway Line 3. The surface settlement and vault settlement characteristics during construction are investigated. The results show a gradual increment in both surface and vault settlement throughout the construction process, culminating in a stabilized state upon the completion of construction.In addition, compared to the double-side drift method and the Cross Diaphragm Method(CRD) method, the suspension method can obviously reduce the surface settlement and vault settlement. Moreover, the surface settlements and the axial force of tie rods were continuously monitored during the construction process at the trial tunnel block.These specific monitoring measurements are illustrated in comparison to numerical analysis results. The monitored results show great agreement with the numerical predictions, confirming the success of the project. This research can serve as a valuable practical reference for similar projects, offering insights and guidance for addressing ground surface settlements and enhancing construction safety in the domain of large cross-section tunneling.

The Study of Force and the Mechanical Characteristic of Incremental Launching Construction Method on a Steel-Concrete Continuous Beam Bridge

The usage of steel-mixed composite beams is quite extensive today.During an event of constructing steel-mixed composite bridges,the incremental launching construction method is generally adopted.This paper mainly analyzes the force of incremental launching construction on a steel-concrete continuous beam bridge,the classification of incremental launching construction,the application of incremental launching construction in steel-mixed composite beams,the temporary facilities existing in incremental launching construction as well as their existing problems.Lastly,the analysis of the stress of composite beams in incremental launching construction is described by using the reference for the construction of mixed composite continuous beam bridges provided.

Guideline of Test Suite Construction for GUI Software Centered on Grey-Box Approach

In this paper, the test suite construction for GUI (Graphical User Interface) software may be executed centered on grey-box approach with the prior test design of window access controls for unit testing, including front-end method of white box and follow-up black box method for integration testing. Moreover, two key opinions are proposed for the test suite construction for GUI software, the first one is that the “Triple-step method” should be used for unit testing with the prior disposing of data boundary value testing of input controls, and another one is that the “Grey-box approach” should be applied in integration testing for GUI software with necessary testing preparation in the precondition. At the same time, the testing of baseline version and the incremental testing should be considered for the test case construction to coordinate with the whole evolution of software product today. Additionally, all our opinion and thought are verified and tested with a typical case of GUI software—PQMS (Product Quality Monitoring Software/System), and results indicate that these methods and specific disposing are practical and effective.

Friction Characteristics Between Marine Clay and Construction Materials

Structure-soil interface friction characteristics is of importance to investigate the interaction between engineering structures and soils,especially for offshore structures.The interface friction behavior between marine clay and structural materials with different roughness was studied in this paper by using 3D optical scanning tests,a modified direct shear device and numerical simulation.Relationships between the surface roughness of structures,water content and interface friction angle were presented by model tests.The increase of water contents decreased the interface friction angles.For interfaces with different roughness,the interface friction angles will be smaller than that of the soil when the water content exceeds a certain value.The roughness of the interface and the water content of the soil are mutually coupled to influence the coefficient of friction(COF).This paper proposed a Finite Element Method(FEM)to simulate the interface direct shear tests of structures with different roughness.The surface models with different roughness are established based on the structure data obtained by 3D scanning.The Coupled Eulerian-Lagrangian(CEL)approach was employed to analyse soils sheared by irregular surfaces.The interface behavior for interfaces with different roughness under cyclic shear stresses was analyzed by FEM.

Exploring the feasibility of prestressed anchor cables as an alternative to temporary support in the excavation of super-large-span tunnel

Excavating super-large-span tunnels in soft rock masses presents significant challenges.To ensure safety,the sequential excavation method is commonly adopted.It utilizes internal temporary supports to spatially partition the tunnel face and divide the excavation into multiple stages.However,these internal supports generally impose spatial constraints,limiting the use of large-scale excavation equipment and reducing construction efficiency.To address this constraint,this study adopts the“Shed-frame”principle to explore the feasibility of an innovative support system,which aims to replace internal supports with prestressed anchor cables and thus provide a more spacious working space with fewer internal obstructions.To evaluate its effectiveness,a field case involving the excavation of a 24-m span tunnel in soft rock is presented,and an analysis of extensive field data is conducted to study the deformation characteristics of the surrounding rock and the mechanical behavior of the support system.The results revealed that prestressed anchor cables integrated the initial support with the shed,creating an effective“shed-frame”system,which successively maintained tunnel deformation and frame stress levels within safe regulatory bounds.Moreover,the prestressed anchor cables bolstered the surrounding rock effectively and reduced the excavation-induced disturbance zone significantly.In summary,the proposed support system balances construction efficiency and safety.These field experiences may offer valuable insights into the popularization and further development of prestressed anchor cable support systems.

Optimization of construction machinery scheme of cast-in-situ concrete based on the improved scatter degree method

The basic requirement of mechanical construction of cast-in-situ concrete is that it could not only conduct quality qualification and safety production, but also achieve most economic benefits with less investment under the condition to meet the needs of project duration. Therefore, the selection of construction machinery scheme plays an important role. However, in the actual construction, it is usually that operators rely on their own experience and field conditions to determine the mechanics. Such a method is subjective and arbitrary, and it is not conducive to make the construction rationally. Considering the above reasons, an improved weight coefficient method was used to establish an estimation model to estimate the construction machinery scheme of cast-in-situ concrete, so as to make the procedure much rational.

A Review of Deepwater Pipeline Construction in the U.S. Gulf of Mexico-Contracts, Cost, and Installation Methods

The offshore pipeline network in the U.S. Gulf of Mexico is the largest and most transparent system in the world. A review of deepwater projects in the region provides insight into construction cost and installation methods and the evolution of contract strategies. Pipeline projects are identified as export systems, infield flowline systems, and combined export and infield systems, and three dozen deepwater pipeline installations from 1980–2014 are described based on Offshore Technology Conference(OTC) and Society of Petroleum Engineers(SPE) industry publications and press release data. Export lines and infield flowlines are equally represented and many projects used a combination of J-lay, S-lay and reel methods with rigid steel, flexible line, and pipe-in-pipe systems. The average 2014 inflation-adjusted cost for pipeline projects based on OTC/SPE publications was $2.76 million/mi and ranged from $520 000/mi to $12.94 million/mi. High cost pipelines tend to be short segments or specialized pipeline. Excluding the two cost endpoints, the majority of projects ranged from $1 to $6 million/mi. The average inflation-adjusted cost to install deepwater pipelines in the U.S. Gulf of Mexico based on available public data is estimated at $3.1 million/mi.

Research on the Reform of the Course“Reading of Concrete Structure Plan and Construction Drawings”Under the Background of“Promoting Teaching and Learning Through Competitions”

The inherent teaching approach can no longer meet the demands of society.In this paper,current issues within the teaching landscape of architectural engineering technology in higher vocational colleges as well as the policies and teaching demands that formed the basis of this model were analyzed.The study shows the importance of the implementation of the teaching model“promoting teaching and learning through competitions.”This model puts emphasis on the curriculum and teaching resources,while also integrating the teaching process and evaluation with competition.These efforts aim to drive education reform in order to better align with the objectives of vocational education personnel training,while also acting as a reference for similar courses.

Professionals’ Perceptions on Construction Progress Measurement Methods Used in Ghana

Progress measurement is cardinal for effective project delivery. It assesses the physical amount of completed work within budgeted cost and manpower performance at a specified stage of the project. Effective progress measurement facilitates progress monitoring, an inevitability for identifying early warning?signs and confirmation of structured work proceeding. Different progress measuring methods are available and used for construction projects. They range from the traditional to the contemporary ones like three-dimensional and four-dimensional models. This paper examines current progress measurement methods used in the Ghanaian construction industry. Eight commonly employed methods were identified from the literature?and?rated by sixty-two construction professionals, practicing with tier one construction firms and construction consultancy services. Relative Important Index ranking and Mann-Whitney?U?test statistics were used to rank and check the consistency of survey responses. Cost Ratio ranked?the?highest, followed by Supervisor’s Opinion and Units?Completed. The fourth-ranked method was Time Ratio, then Incremental Milestone before Start-Finish.?Weighted/Equivalent Units?was at?the penultimate with Earned Value Analysis ranked?the?lowest. The study will not only underscore the relevance of the current project progress measurement practices and provoke prolific debates on their merits, but will also serve as a precursor for critical evaluation of the methods with the view to identifying?barriers militating against realistic progress assessment of construction works.

Assessment of Effects of Green Construction by Analytic Hierarchy Process and Fuzzy Synthetic Judgment Method

The index system, code system, and weights of indexes are established to assess the effects of green construction. The index system consists of index level, factor level and sub-factor level. The analytic hierarchy process is used to determine the weights of indexes, and the consistency test indicate that the weight assignment is reasonable. Using fuzzy synthetic judgment method, the assessment model is built, which includes factor set, weight set and conclusion set. An example is given to demonstrate the assessment procedures.

Structural mechanism and construction method of mud and water inrush in Xiangyun tunnel of Guangtong-Dali railway

Mud and water inrush in tunnel is a common problem in the construction process. Nowadays, the research and classification on this are mostly focused on karst situations. According to the characteristics of the surrounding rock and damage forms of the tunnel in the studied area, the author analyzed the geological and structural characteristics of mud and water inrush in tunnel and obtained their construction type. Meanwhile, the advanced water detection under the complex geological conditions was studied by using induced polarization method, transient electromagnetic method and three-dimensional seismic method, it can be concluded that the water-rich fracture zone exists within the detection range with a risk of large mud and water inrush disaster. The concrete construction treatment measures are put forward:①cement-water glass binary slurry is selected as the material for ground and hole grouting, its advantage is that the gel time can be controlled, and it has certain grout ability in the strata with large permeability coeffcient, which is conducive to excavate construction immediately after grouting.②applying the mature retrograde grouting construction can reduce grouting time and improve the excavation efficiency.

The Methodology of Risk Assessment in the Planning of Construction Projects

Any investment project bears some burden of risk. An investor who plans to carry out a building investment must be aware of the hazards that can be encountered while pursuing the project. Risk analysis can be supported by multi-criteria methods, which allow the user to assess the risk level while taking into account various risk-affecting factors. The aim of this article is to present and compare methods for estimating the level of risk. The article shows an example of risk assessment using methods Preliminary Hazard Assessment, Hazard Matrix and the method not used to this type of calculation Indicator method. Conducted in Article calculations show the possibility of using methods from the group of multi-criteria analysis and the results show the usefulness of the methodology developed by the author. This analysis involves a construction development designed for the tourism business. This is an interesting example due to the specific nature of the object and its location. The calculations take into account the difficult implementation conditions and the results show what you should pay attention to when planning investment.