Real Scale Prototype Research Articles

Design and prototyping of miniature wind turbine and power generation section for the exploitation of wind generated by vehicle movement in road tunnels

A strong development of renewable energy is envisioned in order to achieve targets of reduction for greenhouse emissions. In particular, small scale systems for distributed renewable energy production can be very useful to this purpose in urban areas where the generated power can be directly used.In this context, the present paper concerns the aerodynamic and electromechanical design of a small wind turbine for the exploitation of the wind generated by vehicles movement in road tunnels. The generated energy is directly used to power road delineators, usually equipped with LED technology and, therefore, characterized by low energy requirements, DC supply and long life.The first part of the study addressed the definition of the operating conditions of the wind turbine inside road tunnel. Then, the aerodynamic design of the turbine was conducted through CFD simulations maximizing the efficiency with reduced size and cost. The power generation section is chosen and coupled to the turbine for integrated system prototyping. Simulation results prove that power generated by a single wind turbine is suitable to supply 10 delineators maximum, covering about 100 m of tunnel. Moreover, wind turbine performance is also validated through test on a real scale prototype of the complete device.

Scaled versus real-scale tests: Identifying scale and model errors in wave damping through woody vegetation

Vegetation in front of levees, dikes and seawalls can decrease wave energy and therefore contribute to the safety against flooding. However, wave damping predictions by vegetation are still inaccurate due to measurement and modelling uncertainties. Many studies focused on finding reliable predictive tools using scaled flume tests with vegetation mimics. Scaling down vegetation can however lead to discrepancies with realistic scales, known as scale errors. In this work scaled tests were conducted on 3D-printed elastic replicas of willow trees and compared with real-scale experiments. We identified differences in measured wave dissipation between the scaled hydraulic model (1:10) and its real-scale prototype with 5m high live willow trees under storm conditions (1:1). The maximum measured wave damping (30%) was roughly 1.5 times higher than the real-scale experiments (20%). Following the same trend of the real-scale experiments, this amount of wave height damping declined for larger water levels. Largest effects are argued to be due to increased viscous damping (smaller branch Reynolds numbers) and non-exact flexibility scaling. These significant deviations illustrate that full-scale experiments, although expensive, are still needed to validate the results of scaled experiments for woody vegetation. Alternatively, accounting for these discrepancies can make scaled experiments more reliable and expensive real-scale experiments less needed for wave damping studies on woody vegetation.

Strengths and limits of a modular magnetic wall panel system

This paper explores the feasibility of fabricating and employing an innovative appendage-free modular magnetic interior wall system that allows non-technical users to modify interior spaces to their spatial needs without any need for specialized expertise. The modular magnetic wall panel system tested in this study is composed of free-standing panels with magnetized upright frames for tessellated linkage. In this project, real-scale prototypes were produced and roughly tested for stability to verify that manufacturing is possible and to identify areas for design improvement. Forces were enacted perpendicular to the panel façade in free-standing and linked configurations to mimic probable leaning behaviours by users. Results of rough tests confirm production feasibility and the stability of linked panel assemblies but design improvements must be applied to stabilize the free-standing configuration. Design development and possible enhancements are discussed based on findings. Standardized testing of the enhanced prototype is also recommended.

Energy regenerative shock absorber based on a slotted link conversion mechanism for application in the electrical bus to power the low wattages devices

In recent years, using electric buses based on sustainable energy technologies has become very popular due to their advantages of protecting the environment from hazardous pollutants. However, the power supply of electric buses is the most challenging issue and hinders it from making efficient electric buses. In this study, an energy regenerative shock absorber (ERSA) was designed to be employed in the electric bus to harvest kinetic energy from rough road profiles and enhance the efficiency of electric buses. The proposed ERSA is based on a slotted link conversion mechanism to convert linear vibrations to unidirectional rotations of the generator shaft for energy harvesting and comprises four modules: the energy input model, the motion converter model, the model of a generator, and the electrical energy storage model. Firstly, the energy input model induced vibration into the proposed shock absorber; the motion converter model converts linear vibrations to unidirectional rotations using a slotted link conversion mechanism to drive the generator. Subsequently, the generator model generated electric energy stored in the power storage model. The theoretical model was developed, and simulations were performed using MATLAB software; after that, the real-scale prototype was evaluated through an experimental study using a mechanical bench test (MTS machine) under similar parameters. An average output power of 6.591 W with an efficiency of 39.37% was achieved. Moreover, the ERSA system showed a maximum efficiency of 67.7% during sinusoidal excitations of 7.5 mm and 2.5 Hz. Furthermore, the feasibility analysis was conducted to verify the suitability of the proposed system for powering the auxiliary devices in the electric bus. The suggested ERSA can reasonably power light detection, range sensors, stereo vision cameras, an inertial measurement unit, an accelerometer, and a global navigation satellite system.

Generalized friction panel: An innovative passive energy dissipation device for structures subjected to seismic loading

Passive energy dissipation devices are frequently used in structures subjected to seismic action because they do not require an external source of energy. Recent research on this field has focused on passive dissipation panels. A novel type of passive panel called generalized friction panel (GFP) is proposed in this paper. GFP consists of an external metallic frame with horizontal girders placed at different heights. Parallelepiped solid lead blocks having the ability to slide in the horizontal direction within the panel's plane are positioned on the girders. Energy is dissipated by means of the work done by the friction force on the sliding blocks. Experimental and numerical studies were carried out to test the panel's ability to dissipate energy. Firstly, a real scale prototype of a GFP was built and tested on a shaking table. Acceleration and displacement histories of the prototype were measured at certain points. Tests with fixed blocks were carried out to assess the device's capacity to reduce displacements. Experimental results show that GFPs with sliding blocks exhibit lower displacements than GFPs with fixed blocks. Additionally, a simplified frame-based model of a GFP including discrete elements to consider stick-slip motion with Coulomb friction was developed. Good agreement between numerical and test results was observed.

Unmanaged vegetated roofs hydrological performance in subtropical areas: An investigation in São Paulo, Brazil

Extensive vegetated roofs are Nature-based Solution with the ability to manage rainwater runoff in densely built spaces. Despite the large amount of research demonstrating its water management abilities, its performance is poorly quantified under subtropical climates and when using unmanaged vegetation. The present work aims at characterizing the runoff retention and detention of vegetated roofs under the climate of São Paulo, Brazil, accepting the growth of spontaneous species. By using real scale prototypes under natural rain, a vegetated roof hydrological performance was compared with a ceramic tiled roof. By using models with different substrate depths under artificial rain, changes in the hydrological performance were monitored for different antecedent soil moisture contents. Results from the prototypes showed that the (i) extensive roof attenuated from 30 % up to 100 % the peak rainfall runoff; (ii) delayed the peak runoff from 14 up to 37 min and (iii) retained from 34 % up to 100 % the total rainfall. Furthermore, results from the testbeds indicated that (iv) when comparing two rainfalls with same depths, the one with longer duration can saturate more the vegetated roof and thus undermine more its ability to retain water; and (v) when not managing the vegetation, the vegetated roof's soil moisture content loses correlation with the substrate depth, as plants will also develop more and will more effectively restore the substrate retention capacity. Conclusions point to extensive vegetated roofs as a relevant sustainable drainage system in subtropical areas, but demonstrate that its performance is highly dependent on structural factors, weather factors and level of maintenance. Such findings are expected to be useful for practitioners dimensioning these roofs as well as for policy makers towards a more accurate standardization of vegetated roofs in subtropical regions and Latin American developing countries.

Energetic and Structural Retrofit of Existing RC Buildings through Precast Concrete Panels: Proposal of a New Technology and Explorative Performance Simulation

In this paper, we present a proposal for a retrofit system for existing reinforced-concrete (RC) buildings consisting in the use of precast concrete panels, designed for improving both the structural and energetic performance. In particular, the proposed system is conceived to improve both the energetic efficiency, by ensuring high-performance thermal insulation, and the capacity of the structural elements under gravity and seismic loads. Firstly, a detailed description of the proposed technology is provided, which has been tested and assessed on a real-scale prototype. Then, the efficiency of the technique was explored by means of numerical simulations for both the energetic and structural performance. Although no experimental tests are available, the results of our numerical simulations and analyses on a real case-study building reveal interesting insights, highlighting the main pros and cons of the proposal and providing a possible retrofit solution for buildings that do not meet the current European code requirements.

Abutment-Bar Structure Connection Geometry: An Important Design Parameter for Implant-Supported Bar-Retained Overdentures With Cantilever Extension.

When extended distally due to higher loading in the posterior region, implant-supported bar-retained overdentures with cantilever bar extension exhibit greater bending moments on the implants closest to the cantilever bar and increased stresses in the overdenture components. In this study, a new abutment-bar structure connection was introduced to minimize undesired bending moments and reduce the resulting stresses by increasing the rotational mobility of the bar structure on the abutments. Copings of the bar structure were modified to have 2 spherical surfaces, sharing the same center, located at the centroid of the top surface of the coping screw head. The new connection design was applied to a 4 implant-supported mandibular overdenture to create a modified overdenture. Both the classical and modified models had bar structures with cantilever extensions in the first and second molar areas and were analyzed for deformation and stress distribution using finite element analysis, which was also conducted for both the overdenture models without cantilever bar extensions. Real-scale prototypes of both models with cantilever extensions were manufactured, assembled on implants embedded in polyurethane blocks, and subjected to fatigue testing. Both models' implants were subjected to pullout testing. The new connection design increased the rotational mobility of the bar structure, minimized the bending moment effects, and reduced the stress levels in the peri-implant bone and overdenture components, whether cantilevered or not. Our results verify the effects of rotational mobility of the bar structure on the abutments and validate the importance of the abutment-bar connection geometry as a design parameter.

Effect of thermal inertia and natural ventilation on user comfort in courtyards under warm summer conditions

Thermal inertia and natural ventilation are strategies widely used and studied in indoor building performance. However, little analysis has been done on its effect on the outdoor microclimate. Furthermore, this analysis is needed for the specific case of inner courtyards, given that these outdoor spaces are highly affected by their surrounding building surfaces. This study takes a real-scale prototype constructed for the 2019 Solar Decathlon competition in Hungary as a case study to analyze the thermal inertia and ventilation effects on the thermal performance of courtyards. Monitoring data are used to calibrate a simulation model that combines BES and CFD to predict the thermal performance for three wall configurations with different inertia and two situations: the closed courtyard and the ventilated courtyard. Results show that the thermal inertia and ventilation effects inside the courtyard are similar to what is generally observed inside the buildings. Thermal inertia for the close courtyard was able to increase the courtyard tempering effect up to 1.6 °C and comfort up to 1.4 °C UTCI. The ventilation reduced the tempering potential of the courtyard during the day, but it also reduced overheating during the night. Depending on the wind speed it can also increase thermal comfort.

Experimental performance evaluation of a climate-responsive ventilated building façade

Enhancing building energy performance has become a focal point in reducing the environmental impacts of buildings to address climate change. Considering the high share of comfort-related energy use in buildings, and the importance of indoor environmental quality (IEQ), a balance between energy conservation and IEQ provision is required. Building façades are the primary boundary controlling mass and energy flow to and from buildings. Dynamic and climate-responsive façades are potential improvements to existing high-performance façades to enhance IEQ in buildings, as they change their functionality with time, in response to changing environmental loads. A multifunctional, integrated, climate-responsive, opaque, and ventilated building façade (MICRO-V) was designed to regulate the flow of heat, air, and moisture into buildings. The MICRO-V façade has a novel design to pre-condition the fresh air and regulate thermal loads in buildings on a daily and seasonal basis. The multiple components of this façade include phase change materials (PCMs), a bi-directional ventilation module and an adjustable insulation system. In this paper, the thermal performance of this façade was evaluated using long-term experimental tests. The real-scale prototype of the façade was constructed and installed in the full-scale BETOP test cell facility in Toronto, Canada. The results of different tests showed how the façade could pre-condition the fresh air acting as a decentralized ventilation module due to a high heat recovery efficiency of 81%. However, it was also shown that the significant impact of solar irradiance, which requires constant adjustment to the operation schedule of the ventilation fans in the façade.

Innovative prefabricated lightweight slab system of high structural performance

This paper presents a new pre-fabricated lightweight slab system where the relatively high post-cracking tensile capacity of steel fibre reinforced concrete (SFRC) is combined with the high ductility and tensile strength of optimized shape profiles made by cold formed steel sheets for a synergetic result in terms of structural performance. The SFRC fills the longitudinal steel profiles (girders) that have openings in the web for materializing SFRC shear mechanisms that provide very high shear resistance to the slab. This slab system (designated by PreSlabTec) includes a SFRC deck of 40 mm thickness and lightweight blocks serving as permanent moulds to the SFRC and thermal insulation. The transversal stiffness is assured by thin wall tubular steel profiles that remained anchored in the girders due to their openings. PreSlabTec is simple and fast of executing and was conceived for being produced in an automation process of prefabrication industry.For assessing the performance of the PreSlabTec in serviceability and ultimate limit state conditions, an extensive program with almost real scale prototypes was executed and tested under loading configurations for flexural and shear failures. For the flexural loading configurations, the PreSlabTec demonstrated a very high load carrying capacity and ductility performance. The PreSlabTec never failed in shear, despite the very exigent shear loading configurations adopted. The long-term deflection was also experimentally evaluated for the standard design requirement for slabs of residential buildings, and a relatively low average creep coefficient of 0.13 was obtained.Finally, the theoretical approach for the design of PreSlabTec is described and its good predictive performance is demonstrated.

Experimental Validation of a New Antivibration Elastomeric Material Fabricated from End-of-Life Tires for Slab Track Systems with Embedded Rail

Abstract This article is focused on the experimental characterization and validation of a novel elastomeric material fabricated from the grinded end-of-life tires blended with polyurethane resin. This material will be used as a vibration and noise attenuator in railway slab track systems with embedded rail, commonly used in urban areas. Cylinders with different combinations of grain sizes (coarse, medium, and fine) of end-of-life tires and contents of resin were mechanically tested to obtain the Young’s modulus. The most versatile combination consisting in 50 % coarse + 50 % medium size grains was selected. Two real-scale prototypes consisting of a rail surrounded by the rubber mixture and the concrete slab were designed and fabricated to be applied under normal conditions (low attenuation system) and under situations where vibrations could be fatal (high attenuation system). These prototypes were subjected to static, dynamic, and fatigue loading conditions, applying vertical and angular loads, to validate their mechanical performance. In addition, a vibroacustical experimental study was carried out to obtain the frequency response and the receptance functions. A one-degree-of-freedom analytical model was developed to obtain a loss factor η = 0.287 and a vibration attenuation capacity of the system for the human ear peak sensitivity of ∼40 dB. This study proves the validation of this new eco-friendly material to be used as a vibration attenuator for railway traffic.

Simulación de Mallas de Puesta a Tierra Utilizando el Método de los Elementos Finitos en Tres Dimensiones

Este artículo presenta la simulación de sistemas de puesta a tierra utilizando el método de elementos finitos FEM. La simulación se realiza con diferentes escenarios geométricos, resistividad del material, valores de corriente y lugares por donde se inyecta la corriente a la malla de puesta a tierra. El método de FEM se utiliza en tres dimensiones utilizando ANSYS como software de simulación.
 Para validar el modelo de simulación se utiliza un prototipo a escala real de una malla de puesta a tierra en un tanque electrolítico. Tanto la simulación como el modelo real están sujetos a las mismas condiciones.
 Luego se simulan 16 casos de estudio para comparar los perfiles de voltaje simulados. Todos estos resultados permiten analizar y discutir las cualidades de la configuración geométrica de la malla en diferentes escenarios. El objetivo de este proyecto es generar conocimiento aplicable para el diseño de un sistema de puesta a tierra y evaluar resultados como voltaje de paso, voltaje de contacto y GPR o aumento de potencial máximo.

High-Efficiency Control Strategy for 10-kV/1-MW Solid-State Transformer in PV Application

This article proposes a systematic control strategy for solid-state transformer (SST) composed of dual active bridge (DAB) and cascaded H-bridge, which increases SST efficiency over a wide operating range in PV application. In real practice, the PV panel presents a wide voltage range, which could significantly affect SST efficiency, mainly for DAB. To improve the efficiency, a universal loss model for DAB under frequency domain analysis is established. Based on this, the optimum efficiency modulation scheme is derived. Besides the efficiency improvement of DAB from the modulation scheme, this article fully explores extra control freedom, which is an intermediate voltage between DAB and H-bridge. Then, the variable intermediate voltage control scheme is proposed, which reduces the conduction loss and switching loss of DAB. Furthermore, zero-sequence modulation signal injection and the proportional-resonant controller is implemented in the proposed control strategy, which expands the range for further efficiency improvement. Finally, to verify the effectiveness of the proposed method, the experiment is carried out on the submodule and 10-kV/1-MW SST real scale prototype. Under the proposed method, the SST system achieves 0.9% efficiency improvement compared with the conventional method.

Development of functionalised foam for electrostatic discharge applications

ABSTRACT Electrostatic discharge-sensitive devices (ESDS) consist of electronic systems that are easily damaged by electrostatic fields or discharges. To safely stow and transit the ESDS, Bosch Car Multimedia S.A. resorts to thermoformed trays with a specific design for each product configuration. Although efficient, the solutions’ specificity arose logistic issues that created the need for an alternative approach. This paper reports the investigation for the development of a flexible tray, based on an electrostatic-dissipative integral skin foam. First, a commercial integral skin polyurethane foam was evaluated by varying components mixing ratio. Once achieved a suitable combination of hardness and density, post-formulation additives (colour and anti-static) were investigated. Free expansion foaming stages were assessed and cured foams were characterised in terms of electrostatic discharge protection. Moulded foams with variable patterns were developed and evaluated considering the application purpose requirements. Real-scale prototypes of the most adequate concept design were produced and analysed.

Investigating the Performance of a Super High-head Francis Turbine under Variable Discharge Conditions Using Numerical and Experimental Approach

A super high-head Francis turbine with a gross head of nearly 700 m was designed with computational fluid dynamics (CFD) simulation and laboratory tests. Reduced-scale (1:3.7) physical and numerical models of the real-scale prototype were created to investigate the hydraulic performance. According to the CFD analysis, a strong rotor–stator interaction (RSI) between guide vanes and runner blades is observed as a result of the high-speed tangential flow towards runner created by the super high water head as well as the small gaps between the radial blades. At the designed best efficiency point (BEP), there is no significant flow recirculation inside the flow passage and minor loss occurs at the trailing edge of the stay vanes and guide vanes. Maximum velocity is observed at runner inlets due to flow acceleration through the narrow passages between the guide vanes. The elbow-shaped draft tube gradually decreases the flow velocity to keep the kinetic energy loss at a minimum. The laboratory test was conducted on a reduced-scale physical model to investigate the pressure pulsations and guide vane torque (GVT) under variable-discharge configurations, which are key concerns in the design of a high head turbine. Pressure sensor networks were installed at the inlet pipe, vaneless space and draft tube, respectively. The most intense pressure variation occurs at the inlet pipe and elbow at 0.04–0.2 GVOBEP and 1.5–1.8 GVOBEP with a low frequency about 0.3 times of the runner frequency, while the vibration in vaneless zone performs stable with the blade passing frequency caused by RSI. The GVT shows a declining trend and then keeps stable as GVOs increases at synchronized condition. For the misaligned conditions, the torque of adjacent guide vanes differs a lot except at the synchronous angle and maximum absolute value at least doubles than the synchronized condition.

Numerical investigation on the performance of a small scale solar chimney power plant for different geometrical parameters

In recent decades, demand for energy has been significantly increased, and considering environmental impacts and the degrading nature of fossil fuels, clean and emission-free renewable energy production has attracted a great deal of attention. One of the most promising renewable energy sources is solar energy due to low cost and low harmful emissions, and from the 1980s, one of the most beneficial applications of solar energy is the utilization of solar chimney power plants (SCPP). A SCPP is a simple and reliable system that consists of three main components; a solar collector, a chimney (tower) and a turbine to utilize electrical energy. Recently, by the advancement in computer technology, the use of CFD methodology for studying SCPP has become an extensive, robust and powerful technique. In light of the above, in this study, numerical simulations of a SCPP through three-dimensional axisymmetric modeling is performed. A numerical model is created using CFD software, and the results are verified with an experimental study from the literature. After ensuring good agreement with the experiments, chimney’s and collector’s geometric parameters effects and different configurations effects on SCPP performance, simultaneously and additively is investigated. The study introduces an insight to the performance enhancement methods and finding the best configuration of a SCPP model, which will be the basis of a detailed prototyping process. Based on the numerical results, the best configuration of the SCPP has been found as the diverging chimney which enhances the generated power. The results of the study showed that the chimney height and collector radius increase has a positive effect on the power output and efficiency of the system, but when construction and material costs are also considered, each has an optimal value. The maximum impact on the performance is found to be by the chimney tower radius and the collector height and inclination are found to have optimum values considering performance. According to the obtained results, the best performance for the SCPP was obtained with 3.5 m chimney height, 30 cm tower diameter, 400 cm of collector diameter with 6 cm height and zero inclination angle. By the correct selection of the dominant performance parameter which can be done by correctly interpreting the results of this study, “the best” design of a SCPP real scale prototype considering maximum power requirement can be done.

The Vital Contribution of MagLev Vehicles for the Mobility in Smart Cities

The role of transport in sustainable development was first recognized at the 1992 United Nations (UN) Earth Summit and reinforced in its outcome document—Agenda 21. It is also part of objective 11 of UN 2030 Agenda for Sustainable Development. The improvements in the traditional methods of transportation lag behind the necessities. This paper shows that Magnetic Levitation (MagLev) can fulfill the demand and fits with smart grid concepts. Moreover, the levitation method based on the diamagnetic property of high-temperature superconductors in the proximity of rare-earth permanent magnets presents advantages in comparison with other levitation methods. This technological solution was tested with the operation of a real scale prototype inside the campus of the Federal University of Rio de Janeiro (UFRJ), operating since 2014. The paper presents a historical and technological overview of the steps necessary to turn this prototype into a commercial product. The development is framed within NASA’s Technological Readiness Levels (TRL). A new transportation paradigm is on the verge of becoming a reality.

Design and development of a motorized aircraft seat to substitute aisle wheelchairs

Purpose The solution described in this paper allows wheelchair users with reduced mobility or physical disabilities to move independently throughout an aircraft and to board and disembark autonomously. Materials and methods A motorized aircraft seat was developed to substitute current aircraft aisle wheelchairs. The real-scale functional prototype was evaluated in a focus group. The results show that the proposed solution is considered superior to current solutions in nine of twenty requirements and neutral in one of them. There was low agreement among the focus group participants in ten requirements, even though the focus group discussion brought interesting reflections, including positive feedback, critics, and suggestions for further research and development in the field. Results The design concept consists of a motorized wheelchair that becomes the seat of the aircraft when anchored on a docking platform attached to the aircraft fuselage via a seat track. The manoeuvring is allowed by a rotating mechanism, which solves a critical function that is to enable wheelchair manoeuvring in the narrow aisles of aircraft. A parking assistant system aids the control of the motorized wheelchair. Conclusions The main benefits of this solution are to reduce seat transfers during the flight experience and to provide more autonomy and comfort for passengers during flights. IMPLICATIONS FOR REHABILITATION A motorized aircraft seat was developed to replace traditional aircraft aisle wheelchairs. A real-scale functional prototype was built, tested in an aircraft mockup, and evaluated in a focus group. The main benefits of the proposed solution are to reduce the number of chair transfers during the flight experience and to provide more autonomy for passengers. Additional benefits are to allow the passengers to experience less physical and emotional stresses, to enter the aircraft corridor looking ahead, and to sit in any aisle position in the aircraft.

Performance analysis of an improved PCM-to-air heat exchanger for building envelope applications – An experimental study

The applications of PCM-to-air heat exchangers (PAHXs) face operational challenges regarding the local climatic conditions. One of the main issues is the insufficient cooling potential during the phase change material (PCM) solidification process. In order to increase the cooling charging power of the system, in this study, a unique PAHX type is proposed for building envelope applications. The objective is to magnify the thermal radiation losses from the PCM panels to the nocturnal sky during the solidification process. Two real-scale prototypes were designed and constructed to monitor the effect of radiative cooling on the PAHX thermal behavior during solidification. Accordingly, the cooling performance was investigated for different operational scenarios. In addition, specific key performance indicators were defined to analyze the system charging performance. The experimental results proved that exposure to the clear sky during solidification increases the charging power of the system due to the maximized thermal losses by radiation. The results confirmed that the sky condition and the ambient air temperature profile are key factors in determining the cooling potential of the system. It was shown that making use of the radiation thermal loss to the clear sky increased the charging energy by up to 22% of the proposed PAHX application.