New Building Research Articles

Child-Centred Room Acoustic Parameters of Public Preschools in Sweden

Preschool should promote children’s well-being and development, but the indoor sound environment is commonly problematic. The aim of our research project Supportive Preschool ACoustic Environment (SPACE) is to identify acoustic quality factors resulting in a supportive sound environment for children. This paper presents the first phase of the project where acoustic conditions were measured in unoccupied preschool rooms and analysed in terms of reverberation time, early decay time, sound strength, speech clarity, unoccupied sound pressure levels, and several room features. The results were compared with current target values, building year, and socioeconomic status of the preschool. A child perspective on room acoustics was, in addition, applied and it was revealed that children may be exposed to a lower sound strength than adults, and that adults may have better speech intelligibility conditions than children. Rooms in newer buildings had a longer reverberation time in the 125 Hz band, lower unoccupied levels, and lower sound strength. These differences could be explained by the trend towards larger rooms and porous acoustic ceilings in newer buildings. We found no significant correlations with the socioeconomic status. Ongoing work will facilitate an analysis of the correlation between the room acoustic parameters, the sound environment and children’s perception.

Three-dimensional analytical solution of free vibrations of a simply supported composite plate in contact with a fluid

Background:The quantification of fluid–structure interactions is critical for the design and optimization of marine structures. As composite materials gain more traction in naval construction, there is a dire need of modeling tools to detail the dynamic response of composites in contact with fluids. Current structural theories and finite-element simulations offer promising pathways, but their strong hypotheses on through-the-thickness deformations and high computational cost challenge their practical feasibility. Methods:We propose an analytical three-dimensional solution to the free vibration of a bidirectional composite, separating a fluid column from vacuum. We leverage Pagano’s method to describe the three-dimensional displacement field in each ply of the composite plate and the fluid potential in the form of a Fourier series. Results:An analytical solution to the coupled fluid–structure problem is derived by imposing the continuity of displacement and stress at the ply interfaces, as well as boundary conditions on dry and wetted plies. We specialize the solution to sandwich structures of naval interest, offering insight on how the interactions with water can dramatically affect mode shapes and through-the-thickness profiles of displacement and stress. Discussion:The proposed approach provides the foundations for the design of thick composite plates for use in marine structures.

Analysis of Workload on Fibre Ship Development Project Using Workload Analysis and NASA-TASK LOAD INDEX Methods

One of the fibre shipyards in Surabaya has 16 workers who play a direct role in shipbuilding activities. Every year this shipyard experiences an increase in the number of job requests. The more demand for shipbuilding, the workers involved also have to work harder. The purpose of this study is to find out how the workload is owned by the workforce and determine the optimal number of workers so that it can be used as a reference for decision making in the construction of the next ship. This research will use Workload Analysis and NASA-TLX methods. The results of the analysis using the Workload Analysis method resulted in a recommended workforce of 21 people so that 5 additional workers were needed. While the results of the analysis using the NASA-TLX method, the recommended workforce is 28 people, so there needs to be 12 additional workers. With this addition there is no excessive workload owned by the workforce.

Analysis Adhesive Strength of Epoxy DGEBA on The Wooden Boat Hull

Epoxy is a thermosetting material that is widely used as an adhesive. Epoxy has the advantages of good tensile strength, bending strength, and thermal stability. Epoxy is an adhesive that can bind various materials such as steel, copper, wood, iron, cement, plastic, and composites. Epoxy can be cured at room temperature with the addition of a hardener (curing agent). The curing agent affects the strength, hardness, durability, and adhesion strength of the epoxy. Along with the advancement of shipping technology, other alternatives were found in the construction of wooden ships, namely the laminate system. Wood lamination usually uses an epoxy resin material. Research on the strength of laminated materials for wooden hulls is an interesting scientific discussion to obtain new alternative materials that can be applied to wooden hulls. With this lamination method, it is very possible to replace wood because, with lamination, the material in addition to having better strength is also easy to obtain at a cheaper price than wood. Considering that this laminate material is still rarely used on ships, it is necessary to test the adhesive material. This research was conducted to see the mechanical characteristics and evaluate the use of laminated materials. The tests carried out included tensile test, and adhesive test which were carried out in the laboratory to obtain results to analyse the strength and durability of the wooden hull. The adhesive strength of DGEBA epoxy on teak wood has the highest adhesive strength on Epoxy-Amide with a paint coating of 4.43 MPa and tensile strength of 1.5 MPa. Meanwhile, the highest adhesive strength for Epoxy-Amine with paint coating is 4.76 MPa and tensile strength of 3.63 MPa which is applied to teak wood as a wooden ship hull material.

A Study for Digital Transformation Based on Collaboration Master Plan for Shipbuilding & Marine Engineering Industry

In the shipbuilding and marine industry, digital transformation activities are promoted primarily by large shipyards. However, bottlenecks are observed across value chains, and digital transformation effects are reducing because of the cost and technical challenges encountered by supplies. In this study, we proposed a win-win cooperation model for large, small, and medium-sized companies using digital transformation based on the characteristics of the shipbuilding and marine industry through case studies. We investigated the digital transformation progress in German and Korean small and medium-sized enterprises (SMEs). In addition, we identified information-sharing methods and management challenges encountered in enterprise resource planning and manufacturing execution systems in the collaboration process of pipes, panels, blocks, etc. of SMEs that are suppliers of a Korean shipyard, and clarified communication by building a platform based on a common format between shipyards and suppliers. Further, we proposed a standard model of a digital transformation system for enhancing the collaboration between large companies and suppliers and proposed a basic plan including strategies to efficiently and effectively build a digital transformation system based on the standard model.

어선 실습선의 건조에 대한 소음공해 모델 분석

어선 실습선의 건조에 대한 소음공해 모델 분석

Advanced Outfitting Techniques for Shipyard Development: A 2000 GT Shipbuilding Case Study

The shipbuilding sector is currently facing issues due to long manufacturing schedules and delays in ship construction completion. These challenges come from national shipyards' conventional onboard outfitting process for equipment installation, which takes a lengthy time to complete. To address this issue, this study proposes implementing the advanced outfitting system (AOS) approach, which combines the zone outfitting system with the hull block construction method, in building a 2000 GT ship at PT. X in Surabaya, Indonesia. Technical analysis is performed to plan the shipbuilding process using the hull block construction method, and the efficiency of man-hours is calculated by implementing the AOS approach. The study also conducts an analysis of shipbuilding costs and the required shipyard development investment. The technical analysis shows that the AOS approach improves efficiency factors by enhancing material handling and testing activities. The AOS method has an efficiency factor of 50% for on-unit outfitting and 62% for on-block outfitting, compared to on-board outfitting. The construction of a 2000 GT ship employing the AOS approach represents a reduction of approximately 9.6% in working days and a cost-saving of approximately 4.3% when compared to the onboard outfitting method, resulting in savings of IDR 1,933,277,000 or about USD 124,175. To implement the AOS approach, an investment of IDR 3,040,776,000 or about USD 195,310 is required for construction facilities and human resources development. The return on investment is obtained after two 2000 GT ships are completed. As a result, the AOS approach can improve shipbuilding productivity by reducing construction time and costs. This study provides insights into the benefits of implementing modern shipbuilding techniques in the industry.

Fatigue Life Assessment in the Typical Structure of Large Container Vessels Based on Fracture Mechanics

Welding defects are known to cause crack propagation and reduce structural fatigue performance. Based on the Paris theory of fracture mechanics, research is conducted on evaluation methods for analyzing fatigue crack propagation by adopting random loads with long-term distribution that follows the Weibull distribution for the stress ranges of fatigue loads. This approach is combined with the corrective stress intensity factor (SIF) equation and the method for calculating the reference stress and failure criterion. A large container ship is selected for a simulation, and fatigue crack propagation analysis is conducted on typical critical locations. A detailed comparison of the forecasted fatigue life is carried out between fracture mechanics theory and the S-N curve. The results indicate that the fatigue life values obtained using the two methods are of the same magnitude. In general, for the welded structure, the fatigue life value obtained via the fracture mechanics method is shorter than that obtained via the S-N curve method, while, for the free edge of the structure and the unwelded structure, the predicted fatigue life value is closer than that predicted via the S-N curve method. Moreover, the influence of initial crack defects on the fatigue life is investigated, and the results show that the depth of the initial crack will greatly affect the fatigue life of the target ship in typical locations, but the influence of the shape ratio on the fatigue life is limited. Therefore, in the actual ship construction process, controlling the initial crack depth of components is effective for limiting crack propagation and improving fatigue life. The above conclusions and suggestions can serve as a reference for the structural design and fatigue life evaluation of large container ships.

Editorial

The editorial of Thermal Engineering of this issue continues the discussion on scientific research needs in vital areas in which thermal engineering has important participation. The main goal is to motivate the readers, within their specialties, to identify possible subjects for their future research. The naval sector dominates global commerce totalizing more than 80% of volumes transported]. Heavy fuel oil and marine gas oil are the most utilized fuels and make up 2 to 3% of the human produced CO2 dumped in the atmosphere. Until the year 2050, the International Maritime Organization (IMO) is committed to a 50% reduction of ship greenhouse gases (GHG) emissions with predicted full elimination by 2100. However, military ships are expected to require ten times more electric power than current navy vessels. As a result, the all-electric military ship initiative depends heavily on scientific research and development of environmentally benign high density power generation systems. In that scenario, fuel cells bring a possible path to problem solution. The low-temperature Polymer Electrolyte Membrane Fuel Cell (PEMFC) is recognized to be the most popular FC. Although PEMFC has been used in transportation (e.g., vehicular, ships), PEMFC general use still brings several concerns, due to some shortcomings (e.g., water management, platinum content, Nafion membrane high cost, free energy demanding H2 availability). In parallel, there has been a demand to develop innovative and environmentally correct technologies for alternative energy sources to replace traditional fossil and nuclear sources, including the naval sector, for quite a while, and this need is current, and the main hurdles to overcome are the generation and storage of renewable energy in a technically and economically viable way. The mission of Thermal Engineering is to document the scientific progress in areas related to thermal engineering (e.g., energy, oil and renewable fuels). We are confident that we will continue to receive articles’ submissions that contribute to the progress of science.

Research to reduce polarisation in the swedish energy policy debate

Research to reduce polarisation in the swedish energy policy debate Filip Johnsson, Professor at Chalmers University of Technology, argues that research can help to reduce polarisation in the Swedish energy policy debate. Sweden is an industrial country rich in natural resources such as iron ore, timber, and rivers for hydropower generation. These favourable conditions and the fact that Sweden remained neutral in WW2, resulted in strong post-war industrialisation, with many large companies expanding and becoming global players, including iron ore mining, steel companies, automotive industries, telecommunications, and the pulp and paper, shipbuilding and textile industries.

Post-excavation recording and 3D modeling in ship reconstruction: A case study of the Western Ledge Reef Wreck

As with the study of so many shipwrecks, the late 16th-century Iberian Western Ledge Reef Wreck presents many challenges and opportunities. Since its original discovery in Bermuda in the 1960s, through the subsequent excavation and documentation efforts in the early 1990s, to more recent analysis and ongoing research, the archaeological material related to the hull remains of this vessel still offers new avenues to advance our knowledge on ship construction and design. The project demonstrates the value of combining traditional recording and post-excavation documentation with modern methods of 2D and 3D modeling and digital reconstruction of the complex hull geometry, analyzing hydrostatic parameters and performance, and data visualization.

Validation of the estimated ships' emissions through an experimental campaign in port

This paper presents a correlation between the gaseous pollutant concentration measured in port and the estimated in-port ship emissions based on AIS data for the port of Naples. With the aim of better monitoring the quality ship's plumes funnels, the concentrations of Nitrogen dioxide (NO2) and Sulphur dioxide (SO2) have been continuously measured, during an experimental campaign (May–June 2021) at a height of 20 m from ground level.An innovative bottom-up ship emission modeling system with an emission inventory was created; five principal steps were realized: acquisition and cleaning, construction of ship's database, analysis of ship routes and phases in port, calculation of fuel consumption, and emission. The updated methodology bypasses the typical fixed value of specific fuel consumption, which is obtained based on the engine type and fuels and uses a correlation with the real engine load. Several updates were adopted for the emission estimation, abandoning the constant emission factor with the use of a more detailed methodology. The correlation was obtained by taking into account the prevailing winds and the overlap between the experimental campaign and the emission inventory on particular wind sectors. As a results correlations between the pollutant flow rates estimated from the AIS data and the concentrations measured during the experimental campaign, have been find (0.97 for SO2 and 0.80 for NOX).

Design Optimization of a Cavitating 2D Profile in Proximity of the Free Surface

The appearance of AC72 foiling catamarans in the scenario of sailing yacht competitions in 2013 raised attention to this ship design concept, although not brand new in the yacht design history. The drastic drag reduction connected with the elevation of the ship hull outside the water is obtained by the use of a foil, or a system of foils, acting as the wings of a plane, providing a lift force balancing the weight of the ship. Since this lift is proportional (non-linearly) to the ship hull speed, the take-off speed of the hull cannot be low. As a result, since we are travelling in water at high speeds, the occurrence of the phenomenon of cavitation cannot be completely avoided, and the performance of the ship undergoes deterioration. Shaping of the foil profile must consider this peculiar situation, so the design tools commonly adopted for the aero-hydrodynamic hull design optimization are no longer adequate. In this paper, we are considering the optimization of the 2D profile of a foil in three different physical conditions: single fluid, two fluids and two fluids with cavitation. The first is typical of aeronautic wing design, the second of the appendages of a displacement ship, and the third of a foiling ship. Results give evidence of the different requirements for the three different conditions.

District Heating for Poorly Insulated Residential Buildings—Comparing Results of Visual Study, Thermography, and Modeling

Newer buildings have a lower but smoother profile of indoor temperature, while older buildings are less energy efficient. Sometimes, the indoor temperature is unreasonably high, being 25–30 °C. There are buildings where the indoor temperature does not correlate with the outdoor one. Correction factors adjusting convective heat transfer coefficients are suggested. Energy demand is defined using the rate of heat loss and internal heat gains for the given building construction and design consumption profile. We suggest adjusting the setpoints of the secondary supply temperature to keep indoor and return temperatures lower. Correcting a traditional approach when designing a building may minimize energy consumption by 23.3% and increase the annual performance by up to 14.1%. The reductions of thermal peak resulting from a new type of controller adjustment (for instance, discrete) compared to the traditional operation range from roughly 10 to 30%, respectively. A better understanding of the system operation is a necessary step to switch to fourth-generation district heating (4GDH). This methodology is especially helpful in shaving daily peaks of heat demand. Building envelopes ease the charging, maximum storage capacity, and balance of the given generation and demand profiles, which are key factors in achieving the reduction in greenhouse gas (GHG) emissions. Once the heat demand is covered according to the maximum storage capacity for the given generation and demand profile, fewer efforts to modernize a district heating network are required.

Environmental sustainability criteria in the multi-oriented shipbuilding industry in Indonesia

ABSTRACT Preliminary studies have highlighted the potential of Indonesia's geographical, suprastructural, and infrastructural conditions to develop a strong shipbuilding industry, which is crucial for the success of the world maritime axis program and sea toll. However, despite high expectations, the industry faces challenges that threaten business sustainability, leading to bankruptcies. To assess business sustainability, it is essential to establish criteria and sub-criteria, which previous studies have overlooked, focusing only on technical and economic factors. Therefore, this research generally aims to develop and analyze environmentally friendly sustainable criteria in the multi-oriented shipyard industry so that it develops in accordance with the vision, mission, goals and strategies. The criteria development process involves identifying and reviewing relevant articles, classifying and refining the criteria, conducting expert validity testing, Pearson Product Moment validity testing, and reliability testing using the Alpha (Cronbach) method. The expert validity testing indicates that ‘people' received the highest average score of 4.67 among the criteria, and ‘infrastructure' scored the highest in the sub-criteria, with a score of 4.75. The validity testing with the Pearson Product Moment method demonstrates that the criteria and sub-criteria are valid and the reliability of 32 sub-criteria indicating their influence on promoting multi-oriented and environmentally sustainable shipbuilding industries.

Effect of plasma-electrolytic oxidation on mechanical properties of titanium coatings

The process of plasma electrolytic oxidation (PEO) allows to obtain multifunctional coatings with unique properties, including wear-resistant, corrosion-resistant, heat-resistant, electrical insulating and decorative. Therefore, the field of application of these coatings is quite wide: medicine, aircraft construction, shipbuilding, instrumentation, automotive and other industries. The technology is based on the phenomenon of micro-arc discharges promoting the formation of oxide layers on metal surfaces. In this review the technologies of obtaining coatings by plasma electrolytic oxidation on titanium are considered. The experiment on PEO of VT1-0 titanium substrate under anodic treatment with the addition of TiO2 nanoparticles to the electrolyte was carried out. Dense, uniform oxide coatings that do not require additional surface grinding were obtained. The coating thickness values were 18.5-62.4 μm. The influence of PEO on the microhardness of calcium-phosphate coatings formed as a result of this treatment was studied. With a satisfactory thickness of the formed layer (62.4 μm), the surface microhardness value (4.04 GPa) was found to be the highest among all the treatment modes compared, simultaneously with a high elastic modulus value (348 GPa) and a small value of the indenter penetration depth on the coating (968.99 nm). These coatings were formed in an electrolyte containing calcium phosphate with the addition of 0.75g of titanium oxide nanoparticles. The increase of microhardness in comparison with the sample without coating is in 2,5 times. As a result of the carried out researches optimum modes and parameters of calcium-phosphate coatings receiving have been established and defined. It is shown that by changing the composition of the electrolyte of the micro-arc treatment process it is possible to influence significantly the structure, thickness and surface properties of the obtained coatings.

FORMATION AND DEVELOPMENT OF «KRASNOE SORMOVO» PLANT IN THE SECOND HALF OF THE XIX – EARLY XX CENTURY

The relevance of the article is due to the country’s need for stable development of production. The development of heavy equipment industry is one of the key factors in the country’s economy. The accumulated experience helps not only to continue the successful progress, but to improve existing technologies as well.
 
 The purpose of the study is to study the history of shipbuilding development in Nizhny Novgorod region on the example of “Krasnoe Sormovo” plant and evolution of this plant to identify positive and negative sides in the experience of building ships for various purposes.
 
 Materials and methods. The presented article is based on the study of scientific literature, archival materials, and periodicals. The sources that are in the public domain are taken as a basis. When writing the article, various methods of scientific research were used: the concrete historical method, the method of chronological analysis and the method of periodization.
 
 Study results. The article shows the history of development of ship building and railway coach manufacturing in Nizhny Novgorod on the example of “Krasnoe Sormovo” plant. An attempt is made to show the successes and problems in the development of the plant from the time of its foundation until 1917. Since its establishment, the enterprise managed to take a high pace of development and to adapt to changing realities, outputting products necessary for the country at that time. In some areas of shipbuilding, the plant turned out to be an innovator, having produced revolutionary vessels for its time, which for many years became a model for the industry as a whole. Currently, “Krasnoe Sormovo” plant continues to successfully output products needed by the state, relying on the traditions of Volga shipbuilders and using modern technologies.
 
 Conclusions. Each plant in one or another period of its development experiences both ups and crises; in this regard, it is important how quickly the enterprise will be able to convert to the production of products needed in this period. Sormovsky plant is one of the clearest examples of this: in different years, depending on the needs, it produced a variety of products.

Guideline for Preliminary Design Phase of Trawler Type Yachts

Yacht design is a multidisciplinary process that consists of set of iterative sub-processes. The main aim of the whole process is to reach the optimum design that satisfies not only the engineering-related requirements, but also the user’s expectations. In the preliminary design process, determination of the type and the main dimensions of the yacht according to the user’s preferences is followed by the processes such as the general arrangement plan, determination of the hull form and superstructure design, estimation of hydrostatic and hydrodynamic characteristics, etc. In this research, it is aimed to obtain a parametric design framework which enables to reach hull form characteristics, layout parameters and resistance estimation values with respect to various speeds, only by using only LOA of trawler type motor yachts. In this content, 26 trawler type motor yachts were investigated and their hull were modeled for speed-resistance calculations. As a result of the research, graphics and tables were presented that allow to reach the characteristic parameters, which are important in terms of design and engineering, by using only the LOA value in the preliminary design phase of the trawler type motor yachts.

The influence of a circular moonpool on towing resistance of a conical platform

The towing resistance of naval constructions and fuel consumption would increase due to a complicated mechanism known as water motion in a moonpool during transit. To investigate the effects of a circular moonpool on the towing resistance of a conical platform and the characteristics of the flow in the moonpool during the towing operation, both the model test and the numerical simulation approaches were used. Both experimental results and numerical simulations agree well on the total towing resistance. The two's differences are within 10% of one another in terms of absolute value, which shows that the two approaches had good agreement and consistency. The results demonstrate that two vortices have developed in the moonpool. The formation and dissipation of vortices, as well as the resulting change of the water's surface, will result in the loss of energy, increasing the platform's towing resistance. Due to the moonpool, the flow field changes around the platform and raises the differential pressure resistance. In the end, the moonpool will cause a 7%–10% increase in overall towing resistance. The majority of the resistance on the two platforms comes from differential pressure, with frictional resistance making up a very small portion of the total resistance.

Effect of angular motion on accidental hydrogen fires in conceptional ship fuel preparation room with mechanical ventilation

This paper presents a numerical analysis of the effects of angular motion on fire caused by an accidental hydrogen leak in a mechanically ventilated conceptual ship fuel preparation room. Three rotational motions (roll, pitch, and yaw) were applied with periods and amplitudes ranging from 8 s to 2°–10°, respectively. A distinctive feature of this study is the model construction of a hydrogen ship fuel preparation room with a ventilation system, considering the impact of ship motion on the combustion process of a hydrogen fire. The results indicate that the maximum ventilation flow rate varies by 10% depending on the amplitude of ship motion. However, the effect of ship motion on the range of radiated heat produced by a hydrogen fire is small. Regardless of the ship motion conditions, the maximum radiated heat of hydrogen storage tanks and pipelines is 62.24 kW/m2 and 20,110 kW/m2, respectively, which could cause significant damage to major equipment due to the fire. Consequently, to minimize the damage caused by hydrogen leakage, it is necessary to install additional sensors near major equipment and adjust the number of ventilations to quickly discharge the equipment before a fire occurs.