Table of contents

FOREWORD

After the establishment of the People's Republic of China, Romania was among the first countries in the world to have developed diplomatic relations with China (October 5th, 1949) and, in the following decades, the political, economic and cultural relations between the two countries have continuously evolved, being based on friendship, confidence and reciprocal support. Thousands of cooperation projects in almost all sectors of industry, agriculture, education, science, culture etc. were implemented for the benefit of China and Romania. Whilst the post-1989 changes in the Romanian society partially affected the intensity of this fruitful cooperation, more and more Romanian decision-makers and representatives of the business sector, the academia, as well as of the scientific and cultural life have recently understood that reviving the cooperation with China should be a priority. And not only because of the tremendous economic and technological development of China nowadays, but also because of the long-lasting friendship and trust between the two countries.

In recent years, Transilvania University of Brasov has been at the forefront of the academic and scientific cooperation between Romania and China. The establishment of the Confucius Institute in 2012, in partnership with Shenyang Jianzhu University, represented the impulse for a new stage of intensive cooperation between the two universities and also between the two countries. Hundreds of staff and student mobility exchanges, the participation in scientific events in China and Romania, the establishment of new cooperation partnerships in Beijing, Tianjin, Hunan province etc., the establishment of a Chinese language Bachelor's study programme, the implementation of an international joint laboratory project and a "111" project, and the active involvement in the "16+1 cooperation" in the field of forestry and education are only a few examples of this excellent cooperation in recent years. Our university is fully committed to the further development of the academic and scientific cooperation between Romania and China, and we are convinced that the approaching of the 70^th anniversary of the People's Republic of China and 100 years of modern Romania, will represent the beginning of a new stage of intensive cooperation between the two countries for the benefit of our peoples.

List of committees are available in this pdf.

All papers published in this volume of IOP Conference Series: Materials Science and Engineering have been peer reviewed through processes administered by the proceedings Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

The global competition and trends force the manufacturing industry players to permanently innovate, reduce costs and become more environmentally friendly, thus the pressure for eco-friendly, sustainable and more reliable products is rising. The environmental concerns have begun to be increasingly included in sustainable development strategies of the companies since the effects of worldwide pollution have become more and more visible. In manufacturing industry, in machining units, the cutting fluids are an important source of expenses and they can also be a threat for environment and employee's health. This paper presents a study regarding the possibility of replacing the traditional flood cooling in hard turning with minimal quantity lubrication using vegetable biodegradable oils since the scientific community has brought many contributions to the phenomenon of replacing grinding with hard turning. The capability of hard turning to replace grinding in many industrial applications is proved and thus the elimination of harmful coolant and transition to biodegradable cutting fluids seems to be the way of the future in machining.

This paper mainly focuses on the sound directivity of the angular contact ceramic ball bearing applied to the ceramic motorized spindle. The nonlinear dynamic model is proposed with consideration of axial load, nonlinear hydrodynamic forces and interaction between balls and cage. Then the sub-source decomposition method is introduced for the establishment of an acoustic radiation model. Sound pressure levels along the circumferential direction are used as evaluation indexes of sound directivity, and the sound directivity with axial loads at different rotation speed are analyzed. Results indicate that the sound directivity tends to be obvious with the increase of rotation speed, and the axial loads have significant influence on the deviation angles of directivity performance. This work provides insights into monitoring the acoustic performance of ceramic bearings, and can guide further research and development.

The carburizing process is described by the reaction between environment atmosphere and metal surface followed by carbon transfer in a metal matrix. The main issue of heat treatment consist in ensuring the carburizing controlled atmosphere with a superior carbon potential level than metal surface of steel, in the carburizing furnace at a temperature that ensures process development. Obtaining carbon nanofibers relatively easily led to a new carburizing treatment, in the atmosphere full of carbon nanofibers. The use of nanomaterials for carburizing requires less time and best diffusion. The most common area of carbon concentration and residual austenite presence, the edges and corners are sensible reduced, the hardness is higher than the hardness obtained in regular carburizing treatment. Experiments made on samples of steel SAE 3310 have demonstrated the beneficial role of the presence of carbon nanofibers in carburizing atmosphere. It has developed the conclusion that the carburized layer properties depend on the amount of carbon nanofibers, during carburizing.

In this paper is studied the issue of thick steel sheets cutting on abrasive waterjet machine, due to the abrupt curvature of the jet, caused by energy loss at high thicknesses. Depending on the hardness of the processed material, incomplete cutting occurs and it is evident at a thickness of sheets larger than 30-50 mm. Achieving a cutting with different configuration regimes implies on most of the equipment, turning off the machine, a new configuration and restarting the process of abrasive waterjet cutting which leads to the appearance of traces and marks on cut surface. Choosing the parameters in such a way that cutting is achieved (automatic configuration), leads to obtaining an uncut zone at the exit of the material. This uncut area can be eliminated by an oversized configuration of input parameters, or just reduced by a randomly selected configuration. Both cases lead to large economic losses. The correct choice of machining regime for abrasive cutting of thick sheets, depending on the thickness and the hardness of the material is the aim of these studies and proposed calculation method can be implemented.

This paper researches the reduction of the general / overall torsion of multi – story, rectangular, reinforced concrete structures. The general torsion is caused by the distance (eccentricity) between the centre of stiffness and the centre of mass of the structure. During the seismic shaking of the structural systems, the inertia force acts through the centre of mass, while the resistive force acts through the centre of stiffness. Under this coupled lateral - torsional motion, structural members located along the perimeter of the buildings develop increased deformations and stresses due to buildings' twisting, which results in a higher risk of collapse (brittle, non - ductile failure, damage). This leads to the torsional behaviour of buildings, which is one of the most frequent sources of structural damage and failure during strong ground motions. This paper investigates the influence of the cross sectional properties of the structural components / members, to reduce the above mentioned effect as much as possible. The reduction of the eccentricity can be obtained by modifying cross sectional properties of some rectangular reinforced concrete walls, such as the moment of inertia (length and width of the reinforced concrete walls), which are asymmetrically arranged relative to the central reinforced concrete core. The position of these rectangular reinforced concrete walls is known. Finding the optimal height and width of these walls can be done by using a MatLab function, which minimizes the distance between the centre of stiffness and the centre of mass. The obtained results are then verified in a structural software (ETABS 2016), using modal analysis, or the mode – superposition method, to determine the mode shapes of the structure.

The integration purpose of the ecological criteria in the projecting process is preceded by an intrinsic connection between the existential building space and global environment. The starting point is given by the evaluation of the balance amongst the functional resources of both systems, natural and anthropic. Thus, the ecological criteria open a path for the project leaders to identify and to evaluate the renewable resources potential, as alternative sources, and also their impact on the natural environment. In regard of the anthropic geo-system, following the increase of the population density in the urban areas, or of the depopulation of the rural areas due to the migration of the population to the metropolitan areas, the ecological answer is necessary to be concluded with the sustainable spatial planning. This study aims to develop and compare new categories of factors involved in spatial planning projects, having the goal to mitigate the irreversible damages of the natural environment.

The main purpose of this paper is to study the use of Digital Image Correlation in order to determine the Poisson's ratio in the case of aluminium alloy and composite materials under tensile tests. The satisfactory results obtained in the case of specimens made of aluminium alloy prove that Digital Image Correlation is able to satisfy the requirements in order to determine the Poisson's ratio. The testing procedure was carried out for two kinds of composite materials: (1) jute / epoxy composite material; (2) jute / glass / epoxy composite material. During the tests, a digital camera was used to capture the images of the tensile specimen during the tensile test. In order to measure both the longitudinal strain in direction of the tensile force and the transverse strain, the Digital Image Correlation method is used in the post-processing of all images recorded for each specimen. The data of transverse strain related to the longitudinal strain were graphically shown. The initial portion of curve corresponding to the linear portion of the stress-strain curve, was approximated by a linear regression function for each specimen tested. The slope of the fitting line represents Poisson's ratio. The Poisson's ratio, corresponding to the reinforcing plane with fabric for Jute / epoxy composite, is 35.5% greater than the corresponding to Jute / glass / epoxy composite.

The paper presents a method of estimating the failure rate by applying the extrapolation method, for the case of a single jet cold water meter. The predictive reliability of a system (water meter) is the reliability expressed by the reliability indicators resulting from forecast calculations based on the reliability of the component elements. In order to analyze the reliability of the considered water meter, it is divided into component elements or blocks of elements, which are functional or constructive units, whose reliability indicators are determined in operation. The water meter must be seen as a complex product, the structure of which includes a number of elements forming a system comprising a series of elements connected in one whole, that fulfills a specific technical function. The logical connection of the elements and the component blocks gives the logical reliability scheme with the subsystems and structural elements of the pressure measuring means. Finally, the logic mechanical reliability scheme of the water meter is determined, this being analyzed as a functional complex system, expressing the link between the reliability of the component elements and the reliability of the system as a whole.

The paper presents the results of an experimental study conducted on specific measuring devices - water meters of a certain precision class. The aims of the study are to determine the calibration life of the measuring devices as a function of the metrological reliability and, at the same time, to emphasize the parameter deviation as an important research tool for the quality assurance in metrology. This experimental research may be added to former researches performed on different types of measuring devices. Parameter deviation represents an important research tool for the estimation of the calibration life of the measuring devices. It helps to predict the moment in time when the probability density function for the measurement errors exceeds the tolerance interval by a certain percentage, corresponding to the established level of significance. This moment corresponds to the stage in which the considered measuring device needs to be checked and, if necessary, calibrated. The experimental study conducted is aimed at determining the calibration life of water meters of the same type and of a certain precision class. The research performed on the considered water meters aims to establish which the appropriate moment for performing the calibration is for a specific set of measuring devices, moment which can be estimated by using the parameter deviation functions, these being obtained by means of regression analysis.

The paper presents a seismic SSI study that has been conducted for a 242 m long concrete bridge in Braşov, that has deep foundations on drilled piles. The structure is typical for Romania and highly used throughout the country. The seismic soil-structure interaction were performed using the state-of-the-art ACS SASSI software. The soil-structure interaction analyses were performed for both coherent (synchronous) and incoherent (non-synchronous) seismic inputs. The main focus of the study is to evaluate the effects of soil – structure interaction and of the seismic motion incoherency on the bridge dynamic response. The paper includes comparisons of results obtained using the Eurocode 8 analysis procedures and the state-of-the-art seismic soil-structure interaction analysis using ACS SASSI. The final conclusions indicate the limitations of the current bridge design soil-structure interaction modelling and the simplified motion spatial variability modelling in Eurocode 8. Furthermore, the future directions of the research study are presented.

The quality of drills is classically appreciated by measuring the effective cutting time until the appearance of the admissible wear on the land surface. The experimental tries lead to material consumption and also to resulted chips which, in most cases, are cast as a pollution element. The proposed method for assessing quality is based on measuring the electrical current at cutting and substantially reduces the quantity of resulted chips. The case study was developed for HSS ϕ8 drills and shows the advantages of the method and its ecological impact. The experiments were performed using 1C45 steel workpiece material.

Wood is considered to be one of the oldest building materials, alongside stone. Although wood is characterized by a lower durability, due to multiple factors, we can say that it has many uses, especially in rural areas, in the proximity of woods. An important reason for using wood as a building material was its lower processing cost. However, we cannot omit the fact that, in today's Romania, due to changes in the forestry legislation, a "wood crises" has been generated, which led to higher costs in purchasing, processing and transport. Over time, wood has proved its qualities as an excellent building material, due to its physical and mechanical properties. It is a good thermic and phonic isolator, it is light and resistant, especially if it has been treated against fire, woodworms and fungi. This paper presents generalities regarding wood as a building material, updated and specific data about a log cottage, highlighting its advantages and disadvantages, its building and production costs. The case study could represent a small guidance for investors, giving, at the same time, an overview of the current availability of the total volume of wood in Romania.

This paper presents a particular VR implementation done for a real estate developer. This implementation focuses on increasing immersion and is most suitable for properties that are to be built. It is the latest development of the VR4RE (Virtual Reality for Real Estate) project, which aims at saving time and money for both real estate sellers and buyers by employing modern technologies. VR4RE is one of the innovative projects developed by Bluemind Software. This paper also summarizes the history of in-house technological attempts at creating appropriate presentation tools.

A new programming interface, ISO14649, named STEP-NC, has been introduced recently to overcome the drawbacks of the conventional CNC system. Enhanced machining flexibility, interoperability, and adaptability are the key features of this new programming strategy. STEP-NC technology is based on object-oriented concepts and considers machining processes rather than tool motions as in ISO 6983 for machine tool operation. As such, high level machining features and machining parameters are transferred to the CNC controller, which are eventually used for generating axis movements and other operations. The bidirectional data communication facility of this new strategy enables last minute shop floor level modifications of machining operations at the controller level and establishes a communication pathway to feed major modifications, if required, back to the CAD level as well. Accordingly, the new programming interface allows seamless integration in the CAD/CAM/CNC chain and paves the way for Closed Loop Manufacturing facilities. Most CNC controller vendors have not released STEP-NC compliant controllers yet. Therefore, researchers are developing Open Architecture Control systems to execute STEP-NC and operate CNC machines. This paper reviews research and development of STEP-NC controllers in the last decade and the capabilities of Closed Loop Manufacturing with STEP-NC based systems.

The proper work of vertical wind turbine Savonius typed may be negatively influenced by very high wind speed. Usually the wind turbine speed is limited by means of a brake. The turbine speed is limited, but the spindle of the turbine is still subject of increased torque. The paper proposes a new, innovative technical solution that does not counteract increasing the turbine speed above a limit value, but prevents it. The new concept is based on dividing the blade of the turbine into several parallel vertical strips, properly displayed, as to form the shape of a conventional blade. Each strip can rotate against its own vertical axis, to change its orientation in vertical plane. This brings the benefit that when the turbine speed tends to overcome a certain value (dangerous for the turbine) the strips orientation changes, and the surface of the blade becomes a non-continuous one. The area of the blade that faces to the wind reduces, and prevents increasing the turbine speed. When wind speed slows down, the strips are guided back to their initial position by means of some springs. Reorienting the blades is based on centrifugal force generated of turbine rotation, so, it can be concluded that this forms a self-limitation system of turbine speed.

This article is about value engineering, a method to improve the relationship between the function and the cost of a product. Industrial engineers can provide a better value of their products only if their own value becomes better and better, meaning not to reduce the cost of their education, but to increase their role in designing products and processes. The purpose of this analysis is to generate simple principles for understanding, modelling and optimizing this problem. The interaction between the components of the value provides the definition: the special relation between utility and cost catalysed by the wishes and resources of the employers at a specific moment. The article analyses the components that have effects on student's value and proposes a model harmonized with the growing ratio of the industrial area.

Thermal-induced deformation accounts for 40-70% of the total dimensional and shape errors that arise from various sources of machine tools. This paper suggests a hybrid model based on regression-based analysis and computation-based simulation to predict the thermal deformation of high speed motorized spindle. COMSOL Multiphysics was used to obtain the numerical solutions of the thermal deformation, and the PLS algorithm was used to modify the error between the simulation model and the experimental data collected from the spindle test system. The experimental results showed that the proposed hybrid model could predict thermal deformation effectively and accurately, and it can be used for real-time thermal deformation compensation to improve the machining accuracy of NC machine tool.

In the current context of climate change in the world, it is increasingly necessary to implement strategies and ways of action to adapt industrial companies to sustainable production. The implementation of the Lean concept has a particular impact on creating added value, by reducing wastage, production waste and improving efficiency in order to obtain products/services of higher quality. Through a new approach, the authors propose the use of Lean techniques to develop sustainable manufacturing with an impact on the environment and their implementation in the production sectors. The main objective of the paper is to highlight the opportunities and challenges of Lean Manufacturing in the context of sustainable development. At the same time, the application of Green Manufacturing concept is the development of products/services/processes that save energy, natural resources, with beneficial effects on the environment. A starting point in the analysis will consist of the detailed study of the literature regarding the use of this two concepts, the limits that still occur in their implementation and the finding of a methodology for networking them. The results will demonstrate that integrating the two dimensions will lead to increased performance of the system and to the development of a sustainable company.

The paper investigates the thermal and acoustic properties of composites made from wood fibres (WF) and recycled rubber (R) crumbs and acrylonitrile butadiene styrene (ABS) shavings resulted in the particleboards' edge banding. Panels with a target density of 300 kg/m³ were manufactured for testing the thermal conductivity coefficient and sound absorption coefficient. Mixed panels WF:ABS, R:ABS with participation rates (in %) of 10:90, 20:80, 30:70; 40:60; 50:50 and WF:R:ABS with participation rates (in %) of 5:5:90, 10:10:80, 15:15:70; 20:20:60; 25:25:50 were investigated in this paper. The experiment simulated the indoor and outdoor temperature conditions for the winter and summer seasons, namely 20 ºC for indoor and -10 ºC to 35 ºC for the outdoor temperatures. The results show that, with the increase of ABS share, the thermal performance of the panel increases. The presence of WF in the composition has a good influence on the thermal performance of the panels, whilst the presence of rubber brings a better acoustic performance of the composites. The analysis of the results show that the thermal conductivity coefficient (λ) experimentally determined depends on the outdoor temperature and recorded the best value for the composite WF-ABS (0.0434 Wm⁻¹K⁻¹) followed by WF-R-ABS (0.0460 Wm⁻¹K⁻¹) and R-ABS (0.0477 Wm⁻¹K⁻¹). Maximum values were recorded for R-ABS structure at a temperature of 35 ºC (0.0573 Wm⁻¹K⁻¹), but this structure recorded the best sound absorption coefficient (0.87).

Concrete is a large-scale building material with an important impact on environment mainly due to the production technology of cement and also because it consumes depleting mineral resources as aggregates. Therefore, it is necessary to find ways to replace some of its components in order to diminish its pollution effect. One of these is the partial replacement of cement with other cementitious materials and/or the replacement of mineral aggregates with renewable ones. The aim of this study was to investigate the effects on density, compressive strength, and split tensile strength of the concrete in the case of cement replacement by fly ash in a proportion of 10%, 20% and 30% of the volume, in the case of aggregates replacement by 20% of the volume with aggregates made of waste, and then these two cases combined. Even if the experimental results revealed the decrease of mechanical properties by replacing cement and the mineral aggregates, the smaller density of the developed concretes represents an important advantage.

In order to protect the environment and to reduce its pollution, the concrete greening is an important objective to accomplish this goal. Research across the world has expanded to replace some components of concrete with different kinds of alternative ecological materials, including agricultural materials that are readily renewable resources. They may partially replace the mineral aggregates, if they are used in a shredded form, and / or the cement from the concrete composition, if the ash resulting from their combustion is used. When used as an alternative of mineral aggregates, plant aggregates generally have a number of disadvantages, which requires finding a solution which reduces their water absorption, improves the interface between them and the cement matrix, and gives them durability in the resulting concrete. The present study investigated the effect of sodium silicate on plant aggregates made of shredded corn cobs, and on the concrete manufactured with this type of material as a replacement of mineral aggregates by 20%, 50% and 80% by volume. Experimental results revealed that sodium silicate reduced the water absorption of the grounded corn cobs, resulting a lightweight concrete with improved compressive and tensile strength compared to those of the concrete manufactured with untreated plant aggregates. The use of sodium silicate as a concrete additive resulted in an increase of the compressive strength of the concrete manufactured with 50% by volume corn cob aggregates, of the splitting strength in the case of concrete with 20% and 80% by volume vegetal aggregates, and of the density of the concrete manufactured with the highest percentages of plant aggregates which were investigated in this study.

The method of illumination estimation for images affects the effect of retinex algorithm and causes information loss and halo artefact. A multi scale guided filter is proposed to estimate the illumination. In this method, bidimensional empirical mode decomposition is combined with guided filter. Firstly, the image is decomposed into multiple bidimensional intrinsic mode functions and a trend function by bidimensional empirical mode decomposition. Secondly, we use guided filter to estimate illumination information of each bidimensional intrinsic mode functions. Then illuminance component is formed by combining the illuminance information and the trend function. Finally, guided filter is again used to achieve a more accurate illuminance component. The simulation results show that multi scale guided filter can estimate the illumination component deeply and ensure the integrity of the reflection component. In the effect image of retinex algorithm, the contrast is raised by 1, the luminance is raised by 1, the information entropy is raised by 0.18, the clarity is raised by 0.001, and the visual effect is improved as a whole.

In the space folding mechanism, the function of rotation can be provided by the traditional hinge, and additional driving and locking functions are completed by the unfolded and locking mechanism. Thus, such a mechanism is not only of high quality and volume, but also of complex structure. In this paper, a kind of folding hinge mechanism, which is composed of three springs for the expansion of solar canvas, has been designed and analysed. It can perform automatic expansion by the strain energy accumulated after bending and automatic locking by its inherent critical bending moment. The additional locking devices are not required. By using ABAQUS, the influence of tape spring's space layout and bending mode on the bending moment of the combined hinge with three springs in unfolding process has been researched. An optimal combined hinge which has better bending performance is then obtained. The problem of dead point which may exist in the process of expansion in this kind of hinge was successfully avoided.

In order to combine indoor greenery conservation with Internet of Things Technologies, this paper designs an intelligent household greenhouse project with the features of comprehensive sensing, reliable transmission and intelligent processing. Through the analysis of functional requirements of the intelligent household greenhouse system, an intelligent household greenhouse system is designed with the functions of greenhouse environmental data detection, greenhouse environmental control regulation, data remote transmission and human-computer interaction. Its sensor layer collects environmental data in real time based onthe ZigBee wireless sensor network. The network layer STM32 intelligent gateway coordinates with network server, so as to exchange data from sensor layer to application layer, and solve the problems of non-blocking of data sending and receiving as well as concurrent requests of multiple mobile terminals. The application layer is designed into two types. One is a desktop management system as a data storage and analysis center, and the other is a mobile terminal APP. At the same time, we design a communication protocol that is applicable to the interaction of the three-layer structure of the Internet of Things, with the characteristics of simplicity, stability, readability, and scalability. It can avoid the mutual influence of multi-level data exchange and ensure the correctness of data circulation. In the design, the system sensor layer ensures stable transmission of various data and instructions, and the network layer has a high degree of concurrency and real time. And various measurement and control data of the sensor layer can interact with the data of mobile-terminal equipment of the application layer. What's more, the desktop management system and mobile terminal APP can monitor greenhouse data in real time and control various actuators in the greenhouse.

The traditional transfer matrix method used to calculate the critical speed of high-speed spindle motor rotor system will produce large errors. Taking the 170SD30 electrospindle as the analysis object, a high-speed electric spindle dynamics theoretical model was established based on the Riccati method, using Matlab to program and calculate the kinetic parameters of the first three critical speeds and natural frequencies of the high-speed spindle. Finally, the simulation data was compared with experimental data. The results show that the Riccati transfer matrix method is 2.3% more accurate than the traditional transfer matrix method, and it verifies the accuracy and feasibility of the Riccati transfer matrix method, and is of great significance to effectively guide the analysis and design of high-performance and high-speed motor spindle.

Climate change and the exhaustion of natural resources is a topical issue and represents a "to be solved immediately" goal in the development of built environment. The increasing development of buildings affects the natural environment more than any other industrial process. In Europe, the construction sector is responsible for consuming approximately 50% of the natural resources extracted per year, 40% of the energy produced, 16% of the treated water, and also for producing around 36% of the CO₂ emissions and 40-50% of the solid waste. Nowadays, specialists involved in building design have to think, more and more, about the strategies toward high performance buildings, and apply the principles of sustainability to find ways to coexist with the natural conditions, conserving natural resources, preventing land pollution, protecting the environment, and reducing energy consumption. This paper attempts to investigate the results of SWOT analyses on two aspects of the implementation of the principles of eco-innovative design of buildings in Romania: technical regulations for design and execution technologies. Then, analysing cases of green buildings design in the world, and their impact on the environment, it is concluded with the measures to be taken into account for the creation of healthy built areas, by applying the eco-friendly principles in all forms of their manifestation, and also with the protection of the environment surrounding.

The vibration of high speed motorized spindle directly influences the processing quality; through the finite element method, the dynamic magnetic coupling model of high speed motorized spindle rotor system is established. The coupling relationship between the field parameters of electromagnetic and the characteristics of dynamic are considered. At the same time, the influence of electromagnetic coupled on the dynamic vibration characteristics of the rotor system is analysed and the experimental verification is carried out. The results indicate the stator and rotor magnetic density, the magnetic field energy distribution about motorized spindle are also periodic. The skin effect of magnetic field and air gap eccentricity have great influence on radial vibration. With the increase of speed, the centrifugal force of the bearing is increasing; the softening effect of bearing stiffness is obvious; the natural frequency is decreasing; the amplitude of vibration is increasing. The experimental results are in good agreement with the simulation results. The accuracy of the dynamic magnetic coupling model is illustrated.

Environmental pollution, greenhouse effect, intensification due the wide-ranging of organic fuel, as well as care of energy supply to the future generations caused the accelerated development of technologies oriented to the use of renewable energy sources. Some of these technologies are shown in the paper where some examples of the methods to produce electricity and to provide water for irrigations in the places where there is no access to a large electricity grid like small isolated communities, remote consumers, rural villages, inquiring centers, light houses, inaccessible farms, shelters, telecommunication stations are presented. In order to produce electricity a solution of a wind turbine with vertical axis helical rotor shape with good energetic performances is presented. Also, in the paper some considerations regarding the use of renewable energy sources are presented in order to pump water that can be used in different ways including supply water for domestic needs or for irrigation in small-scale area of lands. In this direction two solutions of using renewable energy sources with a wind turbine to pump water for houses and to pump water that is used to irrigate land of small farmers are shown.

A concrete distributor is the key equipment in the production of precast concrete, abbreviated PC, components. Due to the lack of the automatic and intelligent distribution control system for the most domestic concrete distributor, the quality index is poor and the efficiency is low in the concrete distributing process. In order to solve the above problem, the method of constructing a control system is proposed in this paper. This method is based on the theory of multi-agent and the production technology of PC components. The model structure of complex control systems of multi-agent is studied, and the partition mechanism and coordination mechanism of multi-agent for concrete distribution are analysed. Then, the new model of a multi-agent control system for concrete distribution is designed, and the simulation platform of the system is built. The model of the multi-agent control system for concrete distribution designed is beneficial to theory research in the process control of concrete distribution and its application in the field bus control system. Therefore, the foundation for realizing the automation and intelligence of production in concrete distributing is established.

In the process of rapid development of the society, there is inevitably a waste of resources especially for construction industry. Thus, the demand for green buildings increases swiftly. In the cold areas, the winter lasts for a long time, and several months' heating results in the increase of carbon emissions, which has a great impact on our environment, so it is necessary to develop green buildings. Starting from the concept of green building, this paper expounds the development status of green buildings in the cold area, illustrates the importance of developing green buildings in cold areas, and analyzes the problems faced by the development of green buildings in cold areas, and puts forward some suggestions.

The hysteresis widely existing in piezoelectric ceramic actuators seriously affects the positioning accuracy in practical applications. Based on the microscopic displacement mechanism of piezoelectric actuators, this paper studied the displacement mechanism of the electrostrictive effect and the inverse piezoelectric effect from the microscopic polarization mechanism and, at the same time, the displacement mechanism of electric domain reversal in ferroelectric effect. This paper clarified that the inverse piezoelectric effect and the ferroelectric effect are the main causes for the displacement of the piezoelectric actuator. The contribution of the electrostrictive effect microscopically is extremely weak and can be ignored. This paper shows that the relationship between the voltage and displacement of the piezoelectric actuator in the inverse piezoelectric effect is linear, and the hysteresis characteristic mainly exists in the ferroelectric effect. In this paper, we pointed out that there is energy loss during the piezoelectric domain transition of piezoelectric ceramics, and some irreversible non-180° domain steering is the root cause of the hysteresis of the piezoelectric actuator. This paper provides a scientific basis for further hysteresis curves modelling or correcting hysteresis modelling errors of piezoelectric ceramic and for improving the control accuracy of piezoelectric ceramic actuators in practical applications.

With a vast territory and seven climate zones, China's urbanization is constantly improving while building energy conservation and emission reduction are facing severe challenges, especially in severe cold areas. In China's Liaoning Province, urban public buildings and rural residential buildings consume huge amounts of energy. According to the characteristics of Liaoning, "passive technology advanced, active technology second" is the best choice for energy saving and emission reduction. Taking Sino-German Energy Conservation Demonstration Center in Shenyang Jianzhu University as an example in this paper, through analysis of the operation monitoring data of energy consumption, the objective is to provide a good reference method and a design strategy for the near zero energy buildings in the severe cold areas and to verify its feasibility. At the same time, the parametric design technique is applied to feature-based design system, such as multi objective optimization and genetic algorithm combined simulation technology, Rhino Grasshopper Energy plus energy saving technology and cost-benefit analysis model to obtain the optimal solution. It provides innovative technology demonstration for building energy conservation in the severe cold areas.

According to the energy method, the dynamic stability of a crane's telescopic boom under the periodic load is studied, which is known as parametric resonance, based on the design code for a crane (GB/T3811-2008), the stability analysis model of the box telescopic boom can be regarded as variable-section stepped columns. The parametric vibration equation of n-stepped columns which expressed as Mathieu Equation is deduced by the Hamilton Principle, then the Critical frequency equation of dynamic instability regions of the telescopic booms are derived, finally, the effects of damping to the dynamic stability of telescopic boom are discussed. The results show that, the dynamic instability regions are reduced when the damping coefficient is increased and the effect on the second dynamic instability region is more obvious, that means damping improves the structure's dynamic stability.

The space lattice beam is a complex statically indeterminate rod structure which, composed with several beams, is an important process for calculating the internal force and lateral stiffness in the design analysis. First, taking the single-chip truss structure with variable section as research object, each member's force, lateral displacements and flexibility coefficients of the tapered truss with different arrangement in the form of webs are given. Finally, based on the flexibility coefficient of monolithic truss structure, considering it comprehensively with the effects of lateral stiffness caused by the chords and webs, the lateral displacement expressions are deduced for rectangular space truss structure. Result of analysis of examples show that the application of the method mentioned in this paper to calculate the lateral displacement of space lattice beam with variable section is correct and effective which can be used for practical engineering.

The molecular dynamics analysis and experimental investigation of thin film lubrication of silicon nitride (Si₃N₄) and bearing steel(GCr15) under the n-hexadecane-based lubricant were studied. A molecular dynamics method was used to establish a molecular model with Materials Studio7.0 software. Forcite module for Geometry Optimization, Dynamics and Confined Shear in three steps. The effects of pressure and velocity on lubrication properties such as van der Waals energy and shear stress of film lubrication were explored. The Rtec friction and wear tester was used to test the Si₃N₄-GCr15 friction pair with the change of speed and load.

The study is on the properties of diamond coating prepared on milling cutter and its effect on the cutting performance of stone. The method of hot filament chemical vapour deposition HFCVD was used to deposit diamond film coatings on the surface of the cemented carbide milling cutter. The surface morphology, composition and grain orientation of the diamond films on the cemented carbide milling cutter were analysed by using scanning electron microscopy, Raman spectroscopy and X-ray diffraction; the prepared diamond coated milling cutter was used to process the stone experiment, and the cutting performance of the diamond layer cutter with different carbon sources was analysed. The prepared diamond-coated cutter has a small diamond grain size on the surface, typically <111> crystal face disappears, and the grain orientation presents nano-crystalline diamond. Compared to the uncoated cutter, the surface roughness decreases. After coating, the diamond coating on the surface of the cutter did not show obvious shedding, and the amount of wear on the back face of the uncoated cutter was consistent.

The paper explores the synergistic effects due to hybridization of different synthetic reinforcements with flax fibres on the effective mechanical properties of resulted compounds. A commercial epoxy polymer DGEBF is depolyed as embedding material. Accounting for different stacking sequences, from symmetrical to unsymmetrical architectures, the samples were subjected to 3-point bending and their effective mechanical properties retrieved. Positive hybrid effects in the range of 9,5% and 35% for BF/FF and CF/FF architectures, were encountered in the hybrid composite specimens, respectively.

This article presents several strategies to teach university students and professionals in the sector how to reduce the environmental impact of our cities. Firstly, the European Cityzen project is summarized and its application to the city of Seville, more specifically to Tirode Linea, a working class neighbourhood, is described; the viability and functionality of the neighbourhood are analyzed and improvements are proposed so that it can become an area that attains zero emissions. Secondly, the HEREVEA project is presented, which developed software for the feasibility analysis and proposals to improve neighbourhoods. Its usefulness is discussed in a case study carried out in the same neighbourhood. Finally, the experience of how to transmit all this knowledge through university teaching is presented.

In the present Romanian architectural practice for individual houses and/or residential areas, designing the architectural objects in order to function together with the nature seems to be neglected. This happens despite a great variety of bioclimatic solutions materialized in the traditional houses of all the Romanian geographical regions, in an old and rich history of traditional architecture. The approach starts with a historical overview, analyzing several examples of traditional houses in all the regions of Romania so as to identify the traditional bioclimatic solutions used to better adapt the architecture to the environment. This constitutes the source of inspiration for the four modern standard economic bioclimatic (solar) houses designed for the geographical and climatic parameters of Braşov, Romania, and destined for the middle class families. The concept is simple, based on modesty, involving minimum costs for building and using the houses, as well as for a comfortable life. The projects also offer all the premises for an efficient use of complementary systems for producing and storing energy from the environment (if opted for). The aim is to optimize the relation between the natural and the built environment in order to maximize the comfort, efficiency and economy in all the aspects of a family living in a bioclimatic house (form, function, building materials, equipments, living space, quality of life, etc.). In this respect, the architecture of the four standard economic bioclimatic (solar) individual houses presented represents a neutral and simple so-called "extruded box", as an interface between humans and environment, as a chance to better explore ourselves.

There are various practical applications of dispersely reinforced concrete with polypropylene fibers; one of them could be achieving formworks for concrete columns. This paper presents some practical tests showing the combined effect of a lost shuttering made by dispersely reinforced concrete with fibers and a steel reinforced concrete core, for round and square shaped columns. The test results could be considered a contribution to the development of knowledge in the dispersely reinforcement area using one type of polypropylene fibers for which information on their application field are little or missing.

This paper presents the authors' approach to producing customised products. The authors address the support of information sharing and activity synchronization within and between teams. The paper discusses a methodology for modelling data and original software for product data management that includes customers' preferences and specifications. The developed system has the ability to select an activity, as well as machining processes and parameters based on a set of design and production parameters, and to estimate product cost throughout the entire product development cycle. The case study refers to a product type called "energy-efficient windows". Window panes must be delivered to customers in a variety of shapes, dimensions, and materials according to certain specifications. The Access database provides the geometrical data for the next module, the CAD module that is achieved using Solid Works.

With the increase in the income of the population, with the exception of periods of economic crisis, tourism industry continues to grow year after year. An increasing number of people benefit from the products offered by this industry. This observation is valid for Romania as well as for leading states like China. Without innovations in the field, energy consumption in tourism industry will naturally also grow. This paper proposes a management innovation which whose effect will be both the increase of tourism product quality and significant energy savings. It is an innovative way to prepare and serve breakfast. The savings made at the scale of a large five-star hotel, but also in smaller hotels, as well as in tourist boarding houses, will be evaluated. These results will be scaled to the whole of Romania.

The solutions presented in the paper are based on the possibility to obtain stacked bearings by mounting two bearings if the outer diameter of one corresponds to the inner diameter of the second. Another variant is to specifically design an inner ring with two raceways, one for the lower bearing and the other one for the upper bearing. The paper presents solutions of this type by using bearings of the same type (homogeneous). Regardless of the chosen variant, the final solution presents two layers of rolling bodies or, in other words, a single intermediate ring. The construction of nested bearings must primarily take into consideration the balancing of the static and dynamic basic load rating ensured by the two layers of rolling bodies. This objective can be achieved by adequately establishing the radius and number of balls in the two layers. The advantage of such a construction is that it allows obtaining high rotational speeds. From a theoretical point of view, one can conclude that the maximum speed results as the sum of the values for the two bearings.

It is known that tensegrity systems are made of isolated bars subjected only to compression, connected by stretched cables. The use of these structures comes with advantages such as making large openings and low consumption of materials. This paper analyses the problems related to the building and calculation of a 36-meter-long pedestrian bridge. The structure of the bridge is made up of a double arch of compressed bars and tensioned cables, which supports the path by means of cables. The structure has a number of kinematics degrees of freedom and is statically indeterminate in the same time, which means that it can be pretensioned. Pretensioning introduces compression efforts in the bars and tension efforts in the cables, which fixes the kinematic degrees of freedom and confers rigidity to the system, thus resulting a structure which can support the external loads. The paper deals with aspects of structural analysis and static calculation of the structure subjected to loads.

The present article describes the importance of analysing, designing and maintenance of glass structures. Building Information Modelling is a work method that covers the entire lifecycle of a building by centralizing all the information inside a unique 3D model. Glass structures are a special case where precision and proper maintenance are vital for ensuring safe and economic exploitation. The article also illustrates a practical example of designing and maintaining a glass structure using different software solutions available on the market.

In order to provide a theoretical basis for the of construction scaffold design, the influence of the setting of tie member on the maximum bending moment of the scaffold under wind loads was studied. Based on the semi-rigid analysis of scaffold tube joints, the finite element ANSYS software is used to simulate and analyse the scaffold frame, and studying the change rule of maximum bending moment of scaffold upright tube when the setting of tie member is different. The maximum bending moment of the scaffold upright tube was obtained from simulation and analysis by using ANSYS. The comparison and analysis show that, when the tie member was deviated from the main node and only connected with the inner upright tube, the maximum bending moment of the upright tube was increased obviously, and the maximum bending moment of the inner upright tube increases significantly. Research has shown that the setting of the tie member should ensure the simultaneous connection with the inner and outer upright tube. According to the scaffold at different heights of building in the construction, the author proposed a value of the research for the reasonable position of the tie member and the maximum deviation from the main node.

The elaboration of a methodology for determining the acceptability of detected cracks/flaws in a structure has a major practical importance in the overall assessment and life integrity of a structure. The relation given by fracture mechanics links a parameter which describes the stress intensity at a crack tip to a material characteristic – fracture toughness. This relation provides the possibility of assessing the fracture conditions of the structural elements with defects (cracks). An Engineering Critical Assessment is an analysis based on fracture mechanics principles, of whether or not a given flaw is safe from brittle fracture, fatigue, creep or plastic collapse under specified loading conditions.

The paper presents some considerations on the designing and manufacturing process, taking into account structural assessment procedures using fracture mechanics. It also presents a study case – a steel monopole tower on which the method is applied, in order to assessing the possible discovered flaws in the designing phase. Ten types of flaws which can be discovered in the service time of the structure were assessed. Different types of locations were taken into account, thus resulting groups of flaws which were then assessed and compared.

In recent years, with the continuous development of urbanization in China, construction equipment and technology in the field of building are developing rapidly. China has made much progress in this field, but there is also a gap in comparison. Rapid growth needs to follow the appropriate direction of development. In the future, China will further accelerate the speed of urban intensive construction, so it is of great significance to find a correct direction for the development of Chinese cities. Based on this purpose, this paper summarizes the current situation and rules of building equipment and technology in the view of the rapid development of modern architecture and related practical achievements. This article further analyses the building technology and equipment from the aspects of social culture, political economy, laws and regulations, and discipline development. The conclusion is that in the future development of buildings, the energy saving of construction equipment and technology will become an important symbol of construction technology progress. Finally, this paper puts forward the problems existing in the development of construction equipment and technology in China and the ways to solve these problems.

Earth is one of the most commonly used traditional building materials. Recently its usage was reassessed, considering its qualities, with earth being viewed as environmentally friendly and sustainable. Extended research has been done to analyse material qualities and construction techniques. New buildings were developed, some of them with modern architecture and high aesthetic qualities. In this context, the paper proposes an interdisciplinary approach aiming to analyse earth buildings in Romania from an architectural and structural point of view. Furthermore, their potential use in contemporary architecture is evaluated. Currently, local regulations for the usage of earth as construction material are absent and there are only few examples of earth architecture in recent Romanian practice. We propose a necessary analysis for the process of retrieving a traditional building material, which has a high potential for contemporary architecture in our country. The study examines the historical usage of earth as a building material in Romania. The types of buildings and the construction techniques across various regions are identified. An analysis of the specific structural issues of earth buildings in Romania follows. Conclusions are drawn regarding the potential use of earth as a construction material in contemporary Romanian architecture.

For reinforced special constructions with liquid storage roll, the performance exigencies concerning water tightness is essential. If the storage liquids represent potential sources of environmental pollution, the condition of removing external leaks is fundamental. This paper presents the case of the decanters of liquid residual products, resulting from the technological flow of processing animal proteins, employed in a wastewater treatment plant. The exigencies of water tightness performance of the reinforced concrete decanters are ensured by means of a modern, eco-friendly solution, based on the mass waterproofing of fresh concrete. This solution ensures water tightness without the need for any other protection works or external waterproofing, and any corrections can be applied even in the presence of water.

This paper is a study about truss deformations. This truss is supporting a pipe, it can be a bridge, or another structure and can be necessary for protecting rivers. The truss is a welded structure modelled with Weldment Structural Members, which is often found in industrial constructions and it can be constructed in different shapes. In order to sustain a pipeline over a damaged area, some trusses structures were modelled. The pipeline is supported by some support brackets mounted on the truss nodes. Finite Element Analysis is a process which can predict deflection and stress on a structure, here on a truss. A finite element model is a complete idealization of the entire structural part, including the node locations, the elements, material properties, loads and boundary conditions. The purpose of this paper is to find the best form for trusses using SolidWorks and to avoid oversizing these structures.

The paper stresses the importance of taking into consideration those unintentional design occurrences that leave imprints on the object-oriented dimension of the environment. The visual traces registered on surfaces, represent a trigger for creativity. The information captured undergoes a metamorphosis in the perception of the viewer who intuitively puts it to use. The value of these unintended occurrences is given by the incipient quality of further becoming. To this, the perceiver assigns potential renditions in terms of aesthetics or functionality. The unintended occurrences, as mediums for innovation acquires inspirational value. The environment and personal space are open fields of research and a metaphorical bank of data cumulating information on human behaviour and the results of human-object, inter-objectual or object-environment interactions. The paper aims at stressing the importance of decoding visual markers to benefit creativity and aesthetics.

The article stresses the inspirational capacity of spontaneous vegetation condensed in spaces defined by human oblivion, such as derelict structures and untamed lots. According to the holstering capacity of the medium, isolated cases (weeds sprouting on crumbling walls), or emulating natural habitats (wasteland flora) developed into a wasteland nature propagating as a consequence of dysfunctional urbanization. Because of increased infrastructure development and urbanization, spaces passable of accommodating such unintended design occurrences recede. Such crude source of inspiration for inoculating nature into architecture and design is to be found within the parameters of enduring, unintended, free form compositions of opportunistic vegetation. The article aims at hosting an alternative to current urban order, in what concerns a contextualized human-nature interaction, launching a thinking scheme for rewinding and sustaining the urge toward soil and nature.

At present, most prefabricated components in the assembled buildings could be assembled at the construction site. But the connection method is still of traditional nature, such as steel connection and seam filled with cast-in-place concrete. So, our research group proposed a series of different new types of connection schemes based on the idea of connecting steel transfer parts. According to the different parts of the connection, including how to connect the assembled shear wall and the coupling beam by the U type bar connector, how to connect the shear walls by the method of mortise joint in the horizontal direction and how to connect the shear wall with the columns and beams in the frame-shear wall structure by the keyways. As compared with the traditional way, the following observations can be made: By using the steel transfer parts to connect prefabricated components, the internal force can be transferred effectively and the connection reliability is ensured. The design requirement of "strong connection" is easy to be achieved, which can increase the seismic performance of the structure. The field wet operation can be reduced and connection parts no longer need to be welded. The assembly rate is raised greatly in the whole structure. In the meanwhile, the proposed schemes still exhibit some drawbacks which need to be improved by finite element simulations and experimental studies.

In order to solve the mechanical spindle low processing accuracy and precision elements problems which were caused by high speed spindle noise and vibration, a robust and reliable vibration extraction and control scheme of mechanical spindle was proposed. Based on the electromagnetic balancing system and by applying LabV1EW visual instrument, high speed spindle noise reduction and vibration signals filtering were pre- processed and vibration signals sampling, quantization, interception were post-processed. Base frequency vibration signals amplitude and phase were extracted by using different signal extraction methods. Through experiment verification and comparative analysis, the optimal vibration signal amplitude and phase extraction method was selected. By using the influence coefficient method, the influential factors including spindle speed, trial weights magnitude and phase were analysed. The high speed spindle unbalance was calculated and compensated. The high speed spindle electromagnetic balancing device block was controlled accurately. Experimental results showed that the vibration amplitude of the mechanical spindle was obviously reduced and the balance efficiency was greatly improved. The influence coefficient method and the electromagnetic balancing system took an active role in the process of dynamic balancing regulation. Such achievements enriched online dynamic balancing theory and promoted the relevant control technique developments.

In this paper, a new slate grinding machine based on green design is investigated. To save a lot of cast iron, large natural stones are used in the structure of the machine. Three key components of the body frame, the crossbeam and the power head are introduced in detail. In view of the body frame structure, the process of combination of stone and steel is given. The design method of the important parameters of the power polishing head is proposed. The deformation of the crossbeam under the gravity action of the 12 power polishing heads is analysed. Due to the crossbeam moving laterally with all the power heads, they have great inertia. Therefore, it is difficult to control the motion. In this case, a new buffer brake mechanism is proposed and the dynamic process of the crossbeam reversing is analysed. Finally, the calculation method of the required output torque of the driving motor is proposed. The results show that the functions of the slate grinding machine meet the requirements of use, the proposed method of design and analysis is correct and the concept of green manufacturing is realized.

In order to reduce the inertia force and centrifugal force generated when the spindle bearing unit rotates at a high speed and to increase its limit rotation speed, precision, rigidity, service life and reliability, it can meet the high speed and high precision requirements of the spindle system. The innovative design of the ceramic motorized spindle unit, testing and analysis of the comprehensive performance of ceramic motorized spindle and the related research on the intelligentization of the ceramic motorized spindle were carried out. Finally, the current limitations and challenges are discussed, and the future development trend of the numerically-controlled machine tool ceramic motorized spindle is forecasted.

The machined surface quality of hard and brittle materials was studied based on the analysis of the material removal mechanism of ceramics. According to the geometrical relationship of the internal grinding, the equivalent diameter of grinding wheel was deduced. In the internal grinding, the models of undeformed chip thickness, peak-valley surface roughness and arithmetic mean surface roughness were established with the assistance of planar grinding. The proposed models were verified utilizing the orthogonal test of internal grinding Si₃N₄ ceramics. The trend of experimental results was consistent with the theoretical model. The scientific validity of the proposed models was supported by the experimental results, and the investigation provides a theoretical reference and experimental basis for further study on the grinding of ceramic materials.

Nature marble is widely used in architecture, but generally it is irregular in shape. It is necessary to pack regular shapes such as circular and rectangular into irregular marble slabs, with an optimistic way to save material. However, when the arbitrary region is a concave set, it is difficult to recognize its characteristics if the circular item is in the region. An angle bisector method was proposed to avoid overlapping inside circles and ensure the circle is contained in the marble slab. Meanwhile, the mathematical model for packing circle items in an arbitrary region was established based on the heuristic algorithm. The experimental results show that the approach is effective and it can be used not only in a convex region, but also in a concave one.

After evaluating the studio acoustics environment quality and finding problems, related reforms about acoustic were performed, such as consulting the acoustic design code related studio, through testing on background noise, reverberation time, evenness of acoustic field and other acoustic indeces at the coalface, making antithesis and analysis. Catching the defects of studio acoustic design implied that: electronic equipment running lead to the background noise in the studio is too large; the interface material in the room sounds absorption is too little, bringing the reverberation time is too long; the wall sounds absorbing material and reflector position is unreasonable begets the lack of evenness of the acoustic field. According to the problems above, a theoretical analysis and calculation of the overall acoustic of the studio was conducted, finally advancing the reforms plan. The reformation plan consists of processing door and window insulate sounds, increasing the sounds absorption of the material in the studio, and arranging a reflector on the side of the wall evenly. Thus, the plan will cater for the requirements of acoustics ultimately and provide technical reference for the design of an acoustic studio in the future.

In order to further improve the automation degree of assembly building construction, realize prefabricated component intelligentized positioning, this paper applies the convolutional neural network in positioning control in the field of prefabricated component of assembly building, and puts forward a probability search into target region to establish a new method for loss equation algorithm, the method based on multi label classification loss equation modelling with probability search algorithm, in the training process to continuously improve the positive incentive probability score. The simulation results show that the designed convolution neural network can achieve a correct prediction of the assembly location control instruction, and the proposed method can improve the prediction accuracy and convergence of the network model.

The production of concrete products is the key problem of our intrastructure construction, and the automation degree of this production equipment shows the level of science and technology in our construction industry. To promote the development of concrete production technology and increase the degree of its equipment, the production technology and main parts of PC external wall panel mixing production line are analysed and annotated in this paper. This production line consists of a moving device and carriers, cleaning spraying and marking system, placing concrete and vibrating system, surface treatment system and curing System, and so on. This production line is observed, checked and controlled by a cluster control system consisted of center control sub-system, cycle control sub-system of concrete tray, and curing sub-system of concrete product. The study of the large-scale intelligent PC external wall panel mixing production line helps promote our production technology of the concrete products and drive the development of our construction industry.