Comparison of School Building Construction Costs Estimation Methods Using Regression Analysis, Neural Network, and Support Vector Machine

Accurate cost estimation at the early stage of a construction project is key factor in a project’s success. But it is difficult to quickly and accurately estimate construction costs at the planning stage, when drawings, documentation and the like are still incomplete. As such, various techniques have been applied to accurately estimate construction costs at an early stage, when project information is limited. While the various techniques have their pros and cons, there has been little effort made to determine the best technique in terms of cost estimating performance. The objective of this research is to compare the accuracy of three estimating techniques (regression analysis (RA), neural network (NN), and support vector machine techniques (SVM)) by performing estimations of construction costs. By comparing the accuracy of these techniques using historical cost data, it was found that NN model showed more accurate estimation results than the RA and SVM models. Consequently, it is determined that NN model is most suitable for estimating the cost of school building projects.

Research on the Collaborative Education Mechanism among In-School Mentors,Enterprise Mentors,and Counselors from the Perspective of Sanquan Education

This study addresses the issues existing in the current cultivation process of outstanding graduate students and explores the collaborative education mechanism among in-school mentors,enterprise mentors,and counselors in the cultivation of outstanding engineers in the mechanical field based on the perspective of Sanquan education(i.e.,holistic,full-course,and all-round education).Through exploring this mechanism,we attempt to construct a more scientific and efficient education model to enhance students’comprehensive quality and practical skills,thereby meeting society’s demand for high-quality talents in the mechanical field.

Perception and Uses of Stakeholders＇ Power on Health and Safety Risk Management in Construction Projects in Tanzania

Key project stakeholders such as clients, consultant teams, contractors and workers have different sources of power to implement projects. How these powers influence health and safety risk management is not well documented. This article therefore assesses the perception and uses of stakeholders＇ power on health and safety in risk management in construction projects in Tanzania, specifically focuses on sources and types of power, how stakeholders perceive their power, how they use power on health and safety risk management, and what factors hinders their use of power. A case study strategy was adopted and four large on-going construction projects in Dar es Salaam Tanzania were involved. Data was collected through in-depth interviews with clients, consultants, contractors and construction workers. Findings indicate that stakeholders have different sources of power such as technical expertise, legitimate, political position, resources information to influence health and safety risk management. Nonetheless, the use of these powers was generally limited due to low level of knowledge on health and safety risk management among stakeholders, wrong perception on their roles, insufficient health and safety regulations and weak procurement system. The research recommends that, in order to realize health and safety performance through using stakeholder＇s power, there is a need of clear definition of stakeholders＇ role and responsibilities on health and safety, wide knowledge and experiences on health and safety risk management, strong regulatory system and procurement system.

THE STATE OF SUSTAINABILITY BEST PRACTICES IN CONSTRUCTION: A BENCHMARK STUDY

During the last decade,sustainability-related technologies and practices have become increasingly common among construction companies,both in the home office and on the job site.Multiple drivers are fueling this trend,including government policies for sustainability in capital projects and increased recognition of the benefits of sustainable practices in the private sector.However,the extent to which sustainability-related technologies and practices have been adopted by companies in the field has not been systematically documented.This study used semi-structured interviews and field observations to document the sustainability-related practices of 28 construction firms in the eastern United States.The purpose of the study was to benchmark current industry use of construction sustainability best practices.Findings of the study show that most firms have tried sustainability practices in the field on at least some of their projects,sometimes without being aware that those practices were related to sustainability.Considerable variation was observed among self-reported trial and adoption rates across the practices in the inventory.This study serves as a first step toward understanding why some sustainability innovations are being embraced more readily than others,and may lead to a better understanding of how to increase adoption of sustainability innovations.

Integration Mechanism of Ideological and Political Education with Specialized Knowledge in the Course of Green Building Design

This paper aims to explore the integration of ideological and political education with specialized knowledge in the course of green building design.Through an analysis of the green building design course,combined with the current social development background and the need for ecological and environmental protection,the study investigates how to effectively integrate ideological and political education elements into course instruction to enhance the comprehensive quality and green design capabilities of architecture students.The paper analyzes the content and characteristics of the green building design course and proposes an integration mechanism for ideological and political education in green building design teaching,aiming to cultivate architecture talents with green design concepts and good ideological and political qualities.

Research on the Teaching Reform of Building Information Modeling Course Based on“Post,Course,Competition,and Certificate”Integration

With the rapid development of information technology,the utilization of building information modeling(BIM)is increasingly prevalent in the construction industry.In order to cultivate BIM application-oriented talents capable of effectively addressing industry development demands,this study proposes a reform plan for BIM courses that integrates post,course,competition,and certificate.The reform plan implements the teaching methods of post-course integration,competition-based teaching integration,and course certificate integration in the BIM course.It also carries out curriculum reform from four aspects:curriculum system,teaching mode,teaching content,and assessment method.Reform should be implemented to enhance students’professional and practical skills,thereby enabling them to secure improved employment opportunities and prospects for career development.

Practice and Exploration of Ideological and Political Education for Postgraduate Students Under the Mentor Responsibility System

This study aims to address the problems existing in the ideological and political education of postgraduate students,and combines the implementation of the mentor responsibility system to explore the role orientation,work content,and practical effects of mentors in the ideological and political education of postgraduate students.Through questionnaire surveys,interviews,and other research methods,the current situation of ideological and political education of postgraduate students under the mentor responsibility system is analyzed,and corresponding optimization strategies are proposed.

Nonlinear Static Finite Element Stress Analysis of Pipe-in-Pipe Risers

Owing to the complexity of the pipe-in-pipe (PIP) riser system in structure, load and restraint, many problems arise in the structural analysis of the system. This paper presents a new method for nonlinear static finite element stress analysis of the PIP riser system. The finite element (FE) model of the PIP riser system is built via software AutoPIPE 6.1. According to the specialties of a variety of components in the PIP riser system, different elements are used so as to model the system accurately. Allowing for the complication in modeling the effects of seabed restraint, a technique based on the bilinear spring concept is developed to calculate the soil properties. Then, based on a pipeline project, the entire procedure of stress analysis is discussed in detail, including creation of an FE model, processing of input data and analysis of results. A wide range of loading schemes is investigated to ascertain that the stresses remain within the acceptable range of the pipe material strength. Finally, the effects of the location of flanges, the thermal expansion of submarine pipelines and the seabed restraint on stress distribution in the riser and expansion loop are studied, which are valuable for pipeline designers.

Design of a Biomimetic Skin for an Octopus-Inspired Robot - Part I： Characterising Octopus Skin

Octopus skin samples were tested under quasi-static and scissor cutting conditions to measure the in-plane material prop- erties and fracture toughness. Samples from all eight arms of one octopus were tested statically to investigate how properties vary from arm to arm. Another nine octopus skins were measured to study the influence of body mass on skin properties. In- fluence of specimen location on skin mechanical properties was also studied. Material properties of skin, i.e. the Young＇s modulus, ultimate stress, failure strain and fracture toughness have been plotted against the position of skin along the length of arm or body. Statistical studies were carried out to help analyzing experimental data obtained. Results of this work will be used as guidelines for the design and development of artificial skins for an octopus-inspired robot.

The Working Mechanism and An Analytic Method of the Deep Embedded Large Cylinder Structure

The large cylinder is a new-type structure that has been applied to harbor and offshore engineering. An analytic method of the relationship between loads and the structure displacement is developed based on the failure mode of deep embedded large cylinder structures. It can be used to calculate directly the soil resistance and the ultimate bearing capacity of the structure under usage. A new criterion of the large cylinder structure, which discriminates the deep embedded cylinder from the shallow embedded cylinder, is defined. Model tests prove that the proposed method is feasible for the analysis of deep embedded large cylinder structures.

Design of a Biomimetic Skin for an Octopus-Inspired Robot - Part Ⅱ： Development of the Skin Artefact

In order to develop skin artefact for an octopus-inspired robot arm, which is designed to be able to elongate 60% of its original length, silicone nlbber and knitted nylon sheet were selected to manufacture an artificial skin, due to their higher elastic strain and high flexibility. Tensile and scissors cutting tests were conducted to characterise the matrix and reinforcing materials and the skin artefact. Material properties of the individual and the composite materials were compared with the measured properties of real octopus skin presented ill Part I. The Young＇s modulus of the skin should be below 20 MPa and the elastic strain range should be over 60%. The fracture toughness should be at least 0.9 kJ.m 2. Tubes made of the skin artefact filled with liquid were tested to study volume change under deformation. Finite element analysis model was developed to simulate the material and arm structure under tensile loading. Results show that the skin artefact developed has similar mechanical properties as the real octopus skin and satisfies all the design specifications of the OCTOPUS robot.

Hydration process of rice husk ash cement paste and its corrosion resistance of embedded steel bar

Thermogravimetric analysis and electrical resistivity were used to determine the hydration process of cement paste with rice husk ash(RHA)(0−15%)and water-cement ratio of 0.4 in this work.X-ray diffraction(XRD)method and scanning electron microscopy(SEM)were used to survey crystal composition and microstructures of specimens cured for 3 h,1 d,7 d and 28 d.Finally,electrical parameters(electrical resistance and AC impedance spectroscopy)of steel bars reinforced cement paste were investigated to study the effect of RHA on the corrosion resistance.Results showed that RHA could affect the cement hydration by hydration promotion and pozzolanic effect.The evaluation function for electrical resistivity and curing ages fitted well with linear increasing function.The addition of RHA higher than 5%demonstrated a decreasing role in the electrical resistivity of cement paste at earlier curing ages(3−7 d).Meanwhile,when at later curing ages(7−28 d)the result was the opposite.Moreover,RHA demonstrated positive effects on corrosion resistance of steel bars in cement paste.

Two-dimensional PSD based automatic docking of self-reconfiguration modular exploration robot system

Based on the design of a docking mechanism,this paper thoroughly investigates the space automatic doc- king of self-reconfiguration modular exploration robot system(RMERS).The method that leads robot to achieve space docking by using two-dimensional PSD is put forward innovatively for the median size robot system.At the same time,in order to enlarge the detecting extension and the precision of PSD and reduce its dependence on light- ing signal,the PSD was remade by increasing the optical device over its light-sensitive surface.The emission board and LED light scheduling were designed according to docking arithmetic,and the operating principle of docking process was analyzed based on these.The simulation experiments were carried out and their results are presented.

Improving the Unconfined Compressive Strength of Red Clay by Combining Biopolymers with Fibers

To explore an environmentally friendly improvement measure for red clay,the function and mechanism of xanthan gum biopolymer and polypropylene fibers on the strength properties of red clay were investigated by unconfined compressive strength and scanning electron microscopy tests.The test results demonstrated that the contents and curing ages of xanthan gum had significant influences on the unconfined compressive strength of red clay.Compared with untreated soil,1.5%xanthan gum content was the optimal ratio in which the strength increment was between 41.52 kPa and 64.73 kPa.On the other hand,the strength of xanthan gum-treated red clay increased,whereas the ductility decreased with the increase in curing ages,indicating that the xanthan gum-treated red clay started to gradually consolidate after 3 days of curing and stiffness significantly improved between 7 and 28 days of curing.The results also showed that the synergistic consolidation effects of the xanthan gum–polypropylene fibers could not only effectively enhance the strength of red clay but also reduce the brittle failure phenomenon.The strengths of soil treated with 2.0%xanthan gum-polypropylene fibers were 1.9–2.41 and 1.12–1.47 times than that of red clay and 1.5%xanthan gum-treated clay,respectively.The results of study provide the related methods and experiences for the field of ecological soil treatment.

A graphic monitoring method for electric power of VVVF hydraulic system

In order to online monitor the running state of variable voltage and variable frequency(VVVF)hydraulic system,this paper presents a graphic monitoring method that fuses the information of variable frequency electric parameters.This paper first analyzes how the voltage and current of the motor stator change with the operation conditions of VVVF hydraulic system.As a result,we draw the relationship between the electric parameters(voltage and current)and power frequency.Then,the signals of the voltage and current are fused as dynamic figures based on the idea of Lissajous figures,and the values of the electric parameters are related to the features of the dynamic figures.Rigorous theoretical analysis establishes the function between the electric power of the variable frequency motor(VFM)and the features of the plotted dynamic figures including area of diagram,area of bounding rectangle,tilt angle,etc.Finally,the effectiveness of the proposed method is verified by two cases,in which the speed of VFM and the load of VVVF hydraulic system are changed.The results show that the increase of the speed of VFM enhances its three-phase electric power,but reduces the tilt angle of the plotted dynamic figures.In addition,as the load of VVVF hydraulic system is increased,the three-phase electric power of VFM and the tilt angle of the plotted dynamic figures are both increased.This paper provides a new way to online monitor the running state of VVVF hydraulic system.

Impact of indoor thermal comfort on physiological parameters of human body

With the living standards gradually improved,the buildings with safe,comfortable,healthy indoor thermal environment would be the ideal pursuit. But to create the preferable indoor thermal environment,it is necessary to research physiological influence of indoor thermal environment on human body. So a typical region of hot-humid climate in Chongqing,China,was considered as the object to study physiological indexes of human body. And the indoor thermal environment parameters and physiological indexes of human body were the main measurements. 20 volunteer students were organized to take part in the experiments in the laboratory during this summer. And two methods,physical measuring and questionnaire investigation,were used in the experiments. The results show that the increase in indoor air temperature reduces the uncomfortable feeling of air draft. Indoor air temperature has visible effects on MCS (motor nerve conduction speed),SCS (sensory nerve conduction speed),HR (heart rate),the ECG (electrocardiogram)-QT segment and SSEP (short somatosensory evoked potential)-latent period of N9. Therefore,a safe,comfortable and healthful indoor environment can be created by considering these factors.

Optimization Mathematical Model of Pile Forces for Offshore Piled Breasting Dolphins

An optimization mathematical model of the pile forces for piled breasting dolphins in the open sea under various loading conditions is presented. The optimum layout with the well distributed pile forces and the least number of piles is achieved by the multiplier penalty function method. Several engineering cases have been calculated and compared with the result of the conventional design method. It is shown that the number of piles can be reduced at least by 10%～20% and the piles' bearing state is improved greatly.

Numerical Simulation of the Mixing and Hydrodynamics of Asphalt and Rubber in a Stirred Tank

Computational fluid dynamics(CFD)has been used to analyze the mixing process of Asphalt and Rubber(AR)in a stirred tank with a six flat-blade disc turbine(Rushton),a down-pumping 45°pitched-blade turbine(PBTD-6)and a down-pumping propeller(TXL).The two-phase(solid-liquid)flow in the considered stirred tank has been modelled in the framework of an Eulerian-Eulerian approach,a laminar-flow assumption and a multi-reference frame strategy.The following effects have been investigated:The influence of the impeller speed,impeller type,crumb rubber(CR)particle diameter and initial CR particle loading on the quality of the CR particle’s suspension.The outcomes of the numerical simulations have been found to be in good agreement with the experimental results.The most important findings can be summarized as follows.The flow velocity on the lower part of the stirred tank,induced by the Rushton impeller,is the highest for the three considered mixing systems at the same impeller speed.The suspension quality of CR particles increases with the impeller speed.A larger particle diameter and a higher initial CR particle loading lead to an uneven distribution of particles.The degree of homogeneity in the Rushton impeller system is better than that of the PBTD-6 impeller system and the TXL impeller system at the same impeller speed,while the suspension uniformity of the TXL impeller system is the best possible one for the same power consumption.

Evaluation of social network conservation in historical areas of mountainous towns in Chongqing, China

Over recent decades,historical areas conservation has become an important strategy to improve urban competitiveness in the global economy.As shown in existing studies that the conservation of historical areas mainly focused on the physical environment,there is still room for the non-physical study,and researches on the social network conservation in mountainous historical areas are particularly insufficient.Therefore,this paper aims to establish an evaluation system which is helpful for the social network conservation of historical areas.The evaluation system is based on social network analysis and the information of social relationships gathered in field surveys using a specifically designed questionnaire method in four mountainous towns in Chongqing,China.And it was analyzed from three perspectives,i.e.,by the basic statistical properties,condensate subgroup,and centrality.Then five analysis indicators were conceived,including density,lambda set,k-core,degree centrality,and betweenness centrality.The analysis results demonstrate that the social networks of the four towns show different indicators,which are respectively relevant to completeness degree,edgerelatedness level,local stability,structural balance,and concentrated trend of social relationships.Results from SNA modeling indicate that neighborhood residents of historical areas who have more stable and healthier social relationships are relatively not easily be destroyed.The results also illustrate that the social networks structure is influenced by the terrain,form,and function of historical areas,and the change of historical areas is caused by"individual-family-society".Finally,the strategies guiding the social network conservation are put forward from two aspects.These findings suggest that the conservation and management of social network and aborigines in historical areas should be emphasized to increase the collective benefits and vitality.

Burn-resistant behavior and mechanism of Ti14 alloy

The direct-current simulation burning method was used to investigate the burn-resistant behavior of Ti14 titanium alloy.The results show that Ti14 alloy exhibits a better burn resistance than TC4 alloy（Ti-6A1-4V）.Cu is observed to preferentially migrate to the surface of Ti14 alloy during the burning reaction,and the burned product contains Cu,Cu2O,and TiO2.An oxide layer mainly comprising loose TiO2 is observed beneath the burned product.Meanwhile,Ti2Cu precipitates at grain boundaries near the interface of the oxide layer,preventing the contact between O2 and Ti and forming a rapid diffusion layer near the matrix interface.Consequently,a multiple-layer structure with a Cu-enriched layer（burned product）/Cu-lean layer（oxide layer）/Cu-enriched layer（rapid diffusion layer） configuration is formed in the burn heat-affected zone of Ti14 alloy;this multiple-layer structure is beneficial for preventing O2 diffusion.Furthermore,although A1 can migrate to form A12O3 on the surface of TC4 alloy,the burn-resistant ability of TC4 is unimproved because the Al2O3 is discontinuous and not present in sufficient quantity.