bluuebunny/crossref_metadata_2025 huggingface dataset:
Do we need a saw? Carbon-based analysis of facade BIPV performance under partial shading from nearby trees
Authors: McCarty Justin , Waibel Christoph , Galimshina Alina , Hollberg Alexander , Schlueter Arno
Published: December 2023

Building integrated photovoltaics (BIPV) are becoming more common in urban spaces. The impact of shading from nearby trees on BIPV performance and the potential conflict between the carbon sequestration benefits of trees and the carbon mitigation benefits of BIPV is not well documented in research. Therefore, this paper investigates the cost-benefit relationship of the carbon storage potential of trees vs. their shading effects on a nearby BIPV facade from the perspective of a life cycle assessment (LCA) using a high-resolution BIPV model and temporally sensitive tree growth model. The study is based on a typical Swiss residential building with adjacent vegetation and includes various BIPV facade permutations with different cell types, module orientations, inverter types, facade azimuths, grid emissions profiles, and tree planting scenarios. The results indicate that the removal of trees does not necessarily influence the overall carbon balance when considering LCA to the same degree as other features of the model space such as the grid carbon intensity or the configuration of the BIPV array. Furthermore the parametric-based analysis enables reporting on which BIPV configurations operate with the highest system efficiency under partial shading.
Predictive model of solar potential on building façades with the sky view factor as shading indicator
Authors: Altieri Domenico , Saretta Erika , Mauring Tõnu , Boutaleb Mohamed , Branca Giovanni
Published: December 2023

Building façades represent a considerable part of the urban surface and the solar energy they receive can significantly contribute to the whole urban solar potential. Extending the use of building facades to produce more renewable energy can help address the challenges of climate change, promote energy independence, and create economic benefits.

A major challenge in harnessing solar energy from vertical surfaces is the variation of solar availability on urban facades, which can be affected by orientation, neighboring buildings or vegetation. An easy, reliable and robust method for evaluating the solar potential of facades since the strategical stage of the building development can assist experts in designing façades where building integrated photovoltaics (BIPV) can be efficiently implemented.

This study aims to identify a relationship between the variation of the sky view factor (SVF), a measure of the amount of sky that is visible from a given position, and the corresponding reduction of solar irradiation due to shading. This can then be used to predict the solar potential at each point on the façade on a monthly basis only depending on orientation, SVF value and geographical coordinates, drastically reducing the complexity of analysis and without requiring time-consuming tools.
Modeling reflection by structured building-integrated photovoltaics
Authors: Grobe L O , Wasilewski S , Ploerer D , Roeske C
Published: December 2023

Evaluating the reflection of solar radiation by Building Integrated Photovoltaics (BIPV) with structured front-glass is challenging for two reasons. First, the resulting irregular scattering of light cannot be accounted for by simple reflection models. Second, the locations where the evaluation needs to take place cannot be predicted by simple geometric considerations, as in the case of mirror-like reflection. The detailed modelling of a BIPV module featuring a periodical, linear structure based on the scanning of its surface is described. The application of the model is demonstrated in the assessment of solar reflection by a concave array of the modules. The stochastic sampling of the BIPV modules from each location in a dense sensor grid, that is required to ensure that no local concentration of reflected solar radiation is missed, is supported by re-orienting the sensors. Rather than relying on a data-driven Bidirectional Reflectance Distribution Function (BRDF) model of limited directional resolution, the geometric structure of the front-glass is modelled by modulating the normal of a mirror-like surface. The method allows an accurate and dense simulation with moderate computational demand.
Upscaling potential of BIPV for public housing typologies in Singapore
Authors: Gester Maximilian , Waibel Christoph , Grammatas Argyrios , Sing Tien Foo , Schlueter Arno
Published: December 2023

This paper assesses the upscaling potential of Building Integrated Photovoltaics (BIPV) in the public housing stock of Singapore. While the installation of rooftop PV is gaining rapid traction in the city-state, there are still only few existing projects with façade PV. Considering the large share of façade areas available, this paper aims to identify the most suitable building typology for BIPV integration. The research methodologies include a city-wide analysis of solar potentials, photogrammetry-based solar assessments of the four most common housing typologies, and a load-matching analysis of a typical contemporary apartment unit. Furthermore, we conduct a qualitative analysis through interviews with public and private stakeholders, to understand the drivers and barriers of BIPV in Singapore. Our results reveal districts with the the highest total electricity generation potential such as “Bedok”, or others with larger façade than roof PV-potential such as “Bukit Merah”, where buildings often feature eastwards-oriented façades with low window-to-wall ratio, making them ideal for electricity production in the morning hours. Due to higher cloud coverage in the afternoon, Westward-oriented façades have an overall lower potential. The load-matching analysis shows, however, that peak demand in the morning and evening can generally not be met by BIPV only. The analysis of building typologies reveals that geometrically simpler linear buildings built in the 70’s and 80’s have higher total PV generation potential due to larger roof areas and less obstructed façades. The contemporary point towers with irregular façade surfaces show a larger fraction of façade BIPV electricity generation per floor area, exceeding the share of electricity produced on rooftops. A customized BIPV system will be promising for these newer building typologies, supported by soft factors identified in the interviews.
Increasing PV solar collection using the upper edges in balconies
Authors: Valdivia-Sisniegas R H
Published: December 2023

The current increment of electric prices over the world has created economic problems, but it is also a turning point to a serious rethink about the dependency on fossil fuels. Adapting balconies to produce energy with mini PV installations is increasing in many countries, because not only it reduces costs; but also promotes the energy transition and adaptation as well “plug&save” systems has made the access to photovoltaic electricity easier in existing apartments by using the balustrade or parapets in balconies. Moreover, the stock of multi-story building apartments represents a significant number of dwellings, which is in favor of density and sustainable cities. The current evolution of the market is producing lightweight panels, which combined with new patented devices can improve the solar incidence collection; thus, using upper edges in balconies can result in an easy, and flexible way to install and maintain.
Optimization of Building integrated photovoltaic and thermoelectric hybrid energy harvesting system for different climatic regions
Authors: Kang Yong-Kwon , Jo Su-Young , Park Hyo-Lim , Jeong Jae-Weon
Published: December 2023

As energy saving emerges as a critical factor for the sustainable development of humankind, the importance of Zero-Energy Buildings (ZEB) is gradually increasing. Therefore, much research is being conducted on high-efficiency renewable energy technologies that can be applied in urban areas. However, increasing the efficiency of BIPV were proposed and studied because of the need for the renewable energy source. Such as using phase change material (PCM), heat fin, wavelength selection, PV surface temperature decreasing or using a thermoelectric generator (TEG), and convection cooling utilizing the waste heat from the PV. In most previous studies, the performance when each method was analyzed through experiments or simulations. However, the design analysis for maximum performance still needs to be conducted. Therefore, a BIPV combined with a PCM and TEG (BIPV-TEG-PCM) design is analyzed in this study. Herein, the three variables (phase change temperature of the PCM, heat fin spacing in the PCM container, and TEG arrangement) were analyzed through computational fluid dynamics (CFD)-based simulations. Moreover, through multi-objective optimization, the BIPV-TEG-PCM system of the optimal design was derived. Analysis results of the appropriate melting temperature of PCM, heat fin interval, and arrangement of TEG for the proposed system are 40 °C, 12.4 mm, and 187 mm, respectively.
Decarbonising energy supply: the potential impact on district heating networks of the integration of thermal energy storage and substitution of peak load with base load
Authors: Mennel S , Villasmil W , Fischer L , Tuohy P
Published: December 2023

In 2021, district heating networks provided 6.4 TWh of thermal demand in Switzerland, representing a market share of about 6%. This share is forecast to reach 38% by 2050. More than 50% of those networks rely on base load provided by biomass, complemented by fossil fuel peak load. This paper describes a strategy that would see storage being integrated to substitute peak load with base load. A university campus in Scotland acts as the reference use case to test the suggested fixed-order control strategy. Given these study conditions, the capacities of different storage systems are varied, and their potential for substitution and decarbonisation is accounted for. The study indicates that the integration of small storage volumes seems very promising albeit leading to limited results pertaining to decarbonisation. Depending on fossil fuel prices, a full decarbonisation potential depending on large seasonal storage volumes could be found and a value of 0.14 €/kWh could be calculated as economic threshold to fully decarbonise the reference case.
Exploring thermostat override behavior during direct load control events
Authors: Khorasani Zadeh Z , Ouf M , Gunay B , Delcroix B , Larochelle Martin G , Daoud A
Published: December 2023

Direct load control (DLC) is considered a viable solution to promote demand-side energy management, in which the utility provider adjusts consumers’ temperature setpoints via smart thermostats. Users commonly have the option to interrupt DLC and override them by adjusting their thermostat setpoints. However, the occurrence of overrides can have a detrimental impact on the overall efficacy of DLC. The user discomfort and the fact that an override may increase the load unexpectedly on the grid highlight the importance of understanding override mechanisms during DLC and the uncertainty related to occupants’ responses. This study examined user interactions with smart thermostats during DLC events using real-world data from the Ecobee Donate Your Data (DYD) program. According to the results, 35% of DLC was overridden by users, resulting in higher energy consumption during peak periods. A comprehensive analysis of four types of variables was conducted. A decision tree algorithm was used to classify smart thermostat users into two categories: “compliant users,” who rarely override DLC, and “non-compliant users,” who frequently override DLC, based on general information about their behavior and preferences and without any prior DLC experience. Moreover, three distinct types of DLC participants, characterized by their preferences and behaviors, were identified using a clustering algorithm. Classification results provide utilities with insight into where resources and efforts should be allocated to users who are more likely to comply with DLC. Clustering users into different typologies will enable utilities to design targeted and less disruptive DLC better aligned with the needs of DLC participants.
Energy assessment of a district by integrating solar thermal in district heating network: a dynamic analysis approach
Authors: Bilardo M , Kaempf J H , Fabrizio E
Published: December 2023

This work focuses on the energy upgrade of a neighbourhood located in Yverdon-les-Bains, Switzerland. Starting from a potential low-temperature district heating network, the possible integration of new buildings equipped with solar thermal collectors capable of interacting with the network is explored. The methodology proposed in this work focuses on the study of the energy balance of the district at reduced time intervals. Bringing the level of detail to every single hour of the year, the concept of energy balance is superseded by the hourly averaged power balance as a specific tool for a detailed exploration of the energy flows exchanged within the district. Self-sufficiency has also been identified as key performance indicators to better understand the ability of the entire district to satisfy its heating and domestic hot water needs, modelled in CitySim’s urban energy environment. The outcomes have shown that an annual energy balance is ineffective and unrealistic for describing performances of the district. On the other hand, the hourly averaged power balance proves to be a powerful tool for understanding the dynamics of the neighbourhood. The district’s energy flexibility, which relies on energy sharing, is a characteristic that cannot be assessed annually. Using the new proposed methodology to evaluate the district’s thermal energy sharing, it was discovered that the district functions as a Zero Energy District for 28.9% of the year. With the outcomes presented in this study, it is now possible to comprehend how a dynamic performance assessment positively impacts a district’s redevelopment strategies.
Field study of energy and environmental performance of ground source heat pumps retrofitted in a cluster of UK social housing dwellings
Authors: Gupta R , Zahiri S
Published: December 2023

This paper uses an empirical field based approach to examine seasonal variation in heat pump electricity use and indoor temperatures across a cluster of 50 social housing dwellings retrofitted with ground source heat pumps (GSHP). The case study dwellings were co-located in a socially deprived housing estate in Oxford (UK). Time series monitoring data was collected on indoor, outdoor and target temperatures, heat pump electricity use (kWh), space heating and hot water operation status (on/off) in non-heating and heating seasons. Contextual data about the dwellings were gathered through heat pump surveys and energy performance certificates. Results showed 60% rise in electricity use during the heating season with statistically significant correlation observed between indoor and target temperatures, energy efficiency rating and monthly electricity use. When electricity use was normalised for outdoor temperature, lower electricity use per heating degree day (HDD) was observed in the heating season in the majority of dwellings, confirming the efficient running of the heat pumps. Mean daily indoor temperatures were found to be stable across majority of dwellings, with peak electricity use largely happening outside of the national evening peak period of 4pm-7pm. Despite there being a ‘Timer’ mode in relation to outside weather, most of the residents used the ‘Manual’ mode of operation to adjust target temperatures, possibly to overcome the low output temperatures of heat pumps. While resident training will help to enhance understanding of heating controls, smarter operation of heat pumps through automation based on optimisation of indoor and outdoor temperature, occupancy patterns, heating preferences and electricity price signals could result in further energy savings.
The lowest carbon HVAC system could be no system: the design and lifecycle comparison of two heating and cooling options for Canada’s first hempcrete institutional building
Authors: Gerrard Kyle , Thibault Juliette Mollard , Rysanek Adam
Published: December 2023

This paper presents a comparative analysis of lifecycle carbon for two heating and cooling system options: a reversible ductless split ASHP and direct electric baseboards with a radiative cooling paint. It was determined that over a 60-year assessment period including refrigerant leakage, the ASHP contributed between 2 and 7 times the lifecycle carbon of the direct electric, depending on the consideration of the cooling paint. A sensitivity analysis found that the electrical emission factor of the grid and the refrigerant type and leakage reduction measures both had a strong influence on the lifecycle carbon comparison of the two options. The findings of this study are intended to continue advancing the discussion of the true lifecycle carbon impact that mechanical systems contribute to overall building emissions.
Model predictive control of heating in a low energy single-family house
Authors: Nielsen CM , Larsen KHK , Thorsteinsson S , Bendtsen JD
Published: December 2023

This paper presents a control scheme that uses a Model Predictive Control (MPC) approach to manage the heating system of a low-energy single-family house. The house is equipped with an air-to-water Heat Pump (HP) and individually controlled hydronic underfloor heating circuits for each of its 11 heating zones. The MPC scheme is designed to maintain individual room comfort levels in each zone, while incorporating weather forecasts and following a heating reference to allow for load shifting for periods with low energy prices and high Photovoltaic (PV) production calculated by an upper level in a hierarchical control scheme. The focus of the design has been the model structure that allows for fast solutions to the MPC optimisation problem, while still capturing the high complexity, non-linear dynamics of the building. The controller is tested on a high-fidelity simulation model of the house, achieving disturbance rejection and system stabilisation. The rapid solving time makes repeated experiments and longer simulations feasible.
Experimental Validation for Distributed Control of Energy Hubs
Authors: Behrunani Varsha , Heer Philipp , Lygeros John
Published: December 2023

As future energy systems become more decentralised due to the integration of renewable energy resources and storage technologies, several autonomous energy management and peer-to-peer trading mechanisms have been recently proposed for the operation of energy hub networks based on optimization and game theory. However, most of these strategies have been tested either only in simulated environments or small prosumer units as opposed to larger energy hubs. This simulation reality gap has hindered large-scale implementation and practical application of these method. In this paper, we aim to experimentally validate the performance of a novel multi-horizon distributed model predictive controller for an energy hub network by implementing the controller on a complete network of hubs comprising of a real energy hub inter-faced with multiple virtual hubs. The experiments are done using two different network topologies and the controller shows promising results in both setups.
Optimizing positive energy districts
Authors: Haase M
Published: December 2023

A planning tool was developed which is able to integrate renovation strategies on district level as a combination of energy efficiency upgrades for buildings and the use of renewable energy deliver positive energy districts. It combines elements of energy master planning, district development and optimization in a Modelica environment by combining energy demand, circularity and stakeholder engagement on the demand side and life cycle costs in multi-objective optimisation on the supply side. Thus, the tool consists of six dedicated modules for optimizing positive energy districts (PED).
“oPEN Lab” project as an underpin innovation for Positive Energy District solutions in Pamplona
Authors: Kalms A , Cornago I , Ezquer M , Diaz de Garayo S , Arias A , Torres L , San Emeterio D , Irulegi O , Bouchotrouch F , De Groote M
Published: December 2023

With the EU’s goal of climate neutrality by 2050, urban areas should move towards Positive Energy Districts (PEDs) as powerful ecosystems of balanced energy. The aim of this research is to present the methodology that facilitates the implementation of technical and social innovations, designed and implemented through co-creation, specifically for the neighbourhoods of Pamplona (Spain) in the framework of the project “oPEN Lab” on the way to PEN and based on a local Living Lab (LL). This project is a positive consequence of the evolution and achievements in urban, energy and mobility city planning made possible by the methodology, solutions and actions presented in the context of research and innovation projects such as STARDUST and Efidistrict Fwd.
Smart digital campus UniTO: data gathering and visualisation to support sustainability and indoor comfort
Authors: Accardo D , Meschini S , Gasbarri P , Tagliabue L C , Di Giuda G M
Published: December 2023

This research aims to identify and investigate the best digital tools to improve indoor comfort conditions and sustainability through energy efficiency enhancement in educational buildings, integrating data gathered from sensors. By leveraging an existing asset management platform that integrates Building Information Modelling (BIM) and Geographic Information Systems (GIS), data from Internet of Things devices were linked to the BIM model of a test case building creating a digital shadow in order to gather real-time data on indoor conditions, including temperature, humidity, and CO2 levels. The methodology enables continuous evaluation of the building’s state of usage and calls for automatic and frequent updates of data. The digital shadow can display current usage conditions and alarms when conditions exceed what is comfortable, and it allows for immediate feedback through colours based on the internal detected conditions. The platform can be used with business intelligence tools to support strategic choices and enable future innovations, including machine learning techniques to estimate building occupancy and identify any deviations from expected usage patterns. This study presents a promising workflow for creating sustainable and comfortable educational buildings, which could be replicable and scalable in the future.
Supporting urban decision-making processes through supply-side technologies characterisation
Authors: Rodriguez Alonso C , Quijano A , Vallejo Ortega E , Huovila A , Molteni T , Croci E , Urkola I
Published: December 2023

The MAtchUP project (Maximizing the Upscaling and replication potential of high level urban transformation strategies) developed an urban transformation methodology for sustainable city planning, based on demand-side and supply-side characterisations. The supply-side characterisation is based on the Smart City Technology Packages (SCTP), which are groups of solutions from those demonstrated in the Lighthouse cities of the Project, selected based on their replication potential and with the aim to maximise the impact of MAtchUP actions. The SCTPs are organised in the three main pillars of energy, mobility and ICT (information and communication technologies), and its characterisation includes three main fields: a general description (including reasons for implementing the technologies, barriers and benefits), operational model (analysing business models’ archetype, cost structure and financial model), and impact assessment (in the fields of environment, economy and social). Such characterisation is done under common criteria, which allows comparisons among SCTPs. The supply-side methodology included also a PESTEL (political, economic, social, technological, environmental, legal) analysis done by each city in order to evaluate the viability of each SCTP under those circumstances of the city, to finally obtain the most suitable set of solutions to implement.
Transfer learning methodology for machine learning based fault detection and diagnostics applied to building services
Authors: Chavan K , Réhault N , Rist T
Published: December 2023

Machine Learning (ML) models for Fault Detection and Diagnosis (FDD) can automatically detect anomalies in the operation in large facilities or district heating networks and can help tackling energy wastes. Nevertheless, the development of ML-models is a costly and tedious task requiring large amounts of labelled data. Setting up ML-models for a high number of systems is effort and know-how intensive. However, assets like commercial buildings and district heating networks are constituted of systems with similar topologies. Transferring a ML model initially trained on a source system to a multitude of similar target systems, can help reducing the training costs and facilitating the scalability of ML-based FDD in those assets. To enable this, we have developed a methodology that assesses the potential for Transfer Learning (TL) from a source system to target systems by determining the covariate and concept shifts between the source and target domains and integrating the source model into the target system if the TL assessment is positive. We used a patented method for the model development, that combines two ML-models, that are initially trained on a source system by means of a feedback system. We implemented this methodology on district heating (DH) substations, as DH systems typically contain this kind of subsystems with similar topologies and have thus a high scalability potential for TL. Initial findings showed the effectiveness of TL in adapting the source model to the target domain, resulting in enhanced FDD capabilities with significantly reduced training efforts.
Impact of room thermal conditions on thermal response and energy expenditure of people of different body compositions
Authors: Lipczynska A , Blaszczok M , Dorobisz M , Zoglowek D
Published: December 2023

We performed a climatic chamber study with the participation of sixteen people in all BMI categories at different thermal conditions (16.4°C, 22.1°C, 28.0°C) and activity levels (light, medium, high). There was no substantial influence of the BMI value on the thermal and humidity sensations and the thermal preferences of the subjects. Underweight people had the lowest thermal sensation in cold conditions, while obese people declared sensations most similar to neutral in hot conditions. The net energy expenditure values were the highest in all weight groups during cold conditions and the lowest during warm conditions. We observed that energy expenditure increases with an increase in BMI. The energy expenditure variability depending on body fat percentage was entirely different for women and men. In the former group, energy expenditure increased with the increase in body fat content (especially for medium and high activity). In the case of men, this dependence was not noticed – the energy expenditure was at a similar level regardless of the fat content.
Automated workflow for simulating the effect of green façades on indoor thermal comfort
Authors: Marx D , Reitberger R , Kleeberger M , Lang W
Published: December 2023

Climate change mitigation measures include the addition of vegetation to existing buildings to reduce heat stress in hot summers. In this study, the influence of green façades on the indoor climate is modeled by coupling two different numerical simulation tools: The microclimate simulation tool ENVImet is utilized to model the vegetation and surroundings in the first step. Subsequently, the building energy simulation EnergyPlus in Honeybee/Grasshopper is used to model the indoor climate. Using weather data as a link between the tools, different scenarios (traditional self-climbing plants, plant boxes, and green walls) of green façade designs for a residential building are modeled as a case study. Results show a reduction of operative temperature of up to 3.93% for the most efficient design scenario, the green wall, which corresponds to a 20.09% improvement of the predicted mean vote.
Integration of aquaponics aystem with water reuse for housing in hot arid climate: BaityKool(BK), a bio-inspired dwelling prototype in Dubai-UAE
Authors: Mohanan V P , Bruneau D , Garcia F , Lagiere P , Bouzouidja R , Locke J , Dsilva J , Rochuad A , Canigani B
Published: December 2023

In urban areas, there is little space available for vegetation but a potential for food production that merits to be exploited. aquaponics is a coupled system of two technologies of fish farming and soil-less vegetation, a scheme primarily proposed for hot arid regions with limited agricultural land resource availability for sustainable water reuse and food production operation. This research will include the aquaponics system as a provision of food for all occupants of a house in the most environmentally friendly manner possible. In comparison to standard vegetable production, the employment of this form of the aquaponic system results in effective water savings of up to 90% while producing part of the vegetables for salads for the residents of the BaityKool house. This paper presents the technological design of an aquaponic system as well as its architectural integration into a habitat in Dubai-UAE.
The resilience of buildings to climate change: the role of mobile passive systems
Authors: Roca-Musach M. , Alonso-Montolio C. , Cabillo I. Crespo , Coch H.
Published: December 2023

Climate change indicates that we are heading towards higher temperatures worldwide and greater temperature variations. To face this challenge, we need to adapt to coming conditions and minimize negative impacts on people and the environment. In this paper, we aim to generate evidence to inform decision-making when designing buildings in Switzerland by considering possible future climatic conditions and maximizing the time when buildings do not require neither heating nor cooling systems. We compare two cases, a static scenario where passive systems are permanent (wall and roof thermal insulation), and an adaptable scenario that accounts for movable passive systems (interior shutters, cross ventilation, and solar protection). The results show that the adaptable scenario returns over 1000 hours of free-running conditions more than the static case, both for 2050 and 2070. In the static scenario, the free-running period represents 25% of the year, while in the adaptable scenario it represents around 40%. Thus, passive strategies with movable devices can be a suitable approach to adapt buildings to future climate conditions, which would provide larger periods of free-running conditions, lower energy demand, and lower costs on permanent thermal insulation.
Unbalancing mean radiant temperature and air temperature
Authors: Meggers F M , Yazici B , Kim J , Chen K , Merchant C , Izuhara I
Published: December 2023

Radiant heating and cooling systems promise to provide heat transfer over large surface areas to enable lower temperature supply improving both supply efficiency and user comfort. Radiant panels provide both radiant and convective heat transfer. We investigate the balance of the heat transfer occurring via radiation and convection. A commonly referenced benefit of radiant panels is that the radiant heating or cooling delivered to occupants allows thermal perception to remain neutral while lowering or raising air temperatures, which in turn reduces heat losses or gains through the facade. In our previous work on radiant systems, we have observed that very rarely do air temperatures actually get set to more ideal temperatures alongside the radiant panels. Using the framework of a recent study of an office space in Singapore we present a simulation showing the breakdown of radiant and convective heat and the resulting air temperature in a simple heat balance model. We then use a computational fluid dynamics (CFD) model and analytical model to observe the relationship between air temperature and mean radiant temperature (MRT) through space. We find that it can take up to 40 kW of additional heat gain to successfully decouple the air temperature from the MRT generated by the panel by more than 2 °C. We also show that in the CFD model, while the air temperature and MRT remain relatively tightly coupled, the vertical spatial variation of MRT is significant, changing by more than 2 °C across the space from floor to ceiling.
Assessment of drag prediction techniques based on radar data for supersonic vehicles
Authors: Doso M , Khali M , Zakaria M Y , Ahmed M Y
Published: December 2023

Flight testing is probably the most accurate approach for defining the aerodynamic characteristics of a flying vehicle. This is justified by the fact that compared to other approaches, either engineering or computational ones, flight testing is indeed the one that perfectly resembles the real flight environment. Flight data are either obtained by measuring the vehicle’s kinematics via onboard sensors or by tracking the vehicle’s flight via (commonly) radars. The advantages of the latter approach are evident in cases where modifying the vehicle design is not possible or in cases where rival/enemy vehicles are examined. The key issue for this approach is the quality and demands of the technique by which vehicle aerodynamic characteristics are reduced from flight-tracked data. In the open literature, different techniques are used to analyze radar data of vehicle position and utilize them to predict vehicle drag coefficient. Each technique has its strengths and pitfalls. In this paper, the three well-used techniques of drag estimation from radar data namely, Least Square (LS), Maximum Likelihood Estimation (MLE), and Stepwise regression (SR), are considered. The underlying principle, the output, and the range of validity for each technique are addressed with emphasis on what differentiates each of them. The viability and validity of the three techniques are addressed based on the own flight testing of a free-flight supersonic vehicle and using the point-mass flight model. Meteorological data are also recorded and flight conditions are used to enhance the resulting calculations. Based on experimental data available from the literature, a comparison is conducted for the techniques examined. Considering the lack of flight data utilized, and in conjunction with data from the literature, it has been concluded that the SR technique outperforms for a higher sample rate, however, the MLE is more feasible when there is a lack of data.
Position control of Stewart platform with electric linear actuator
Authors: Mohamed M R , Roshdy A A , Ali A A , Fayed M A
Published: December 2023

In recent decades, several technological applications have depended on manipulators like Stewart platform due to its accuracy and precision. Based on actuation type, Stewart platforms could be rotary or linearly actuated. Electric linear actuators are devices commonly consist of DC or AC motors coupled with lead screw or mechanism of gears and spindle which are used to convert rotary motion into linear (push or pull) motion. To increase accuracy and precision and achieve the desired linear actuator response, controllers should be used. The main aspiration of this work is to investigate the feasibility of using PID controllers for position control of Stewart platform with linear actuators. The mathematical model has been derived and the model transfer function has been obtained. To meet the required response of performance characteristics, the PID controller has been designed based on analysis of root-locus. Model simulation analysis has been carried out on both MATLAB and Simulink. For the electric linear actuator, comparison between the obtained response and the results of Ziegler-Nichols tuning method has been discussed on basis of the specifications of the time response. The PID controller parameters for the electric linear actuator has been tested experimentally and compared with simulation results.
Modeling and analysis of nonlinear backstepping controller for the crazyflie quadrotor trajectory tracking
Authors: Zekry O H , Ashry M M , Hafez A T , Attia T
Published: December 2023

This paper illustrates the Newton-Euler laws-based nonlinear dynamic model of a Crazyflie Quadrotor Unmanned Aerial Vehicle (CF-QUAV). It demonstrates the state-space-form equations that govern how the CF-QUAV moves around its frame (body). A Proposed nonlinear control strategy is used to regulate the height (z), position (x, y), attitude (roll and pitch), and heading (yaw) angles. This strategy is based on a Backstepping nonlinear controller defined by Lyapunov theory. The proposed controller can replace the Proportional-Integration-Derivative (PID) controller utilized in the CF-QUAV model to follow the desired trajectories gleaned from CF lab tests. In addition, the parameters of the proposed controller are tuned using the Genetic Algorithm (GA) in order to achieve the best performance and stability of the CF-QUAV model. Simulation-based experiments with statistical analysis are carried out to evaluate the performance of the proposed nonlinear controller and compare its performance and stability with the linear PID controller.
Small RCS targets detection based on pulse compression radar signal generator and processor
Authors: Zahra A G , Youssef A , Talha M , Ahmed F M , Mehany W
Published: December 2023

In the last two decades, field programmable gate arrays (FPGAs) have become the leading technology for implementing real time systems, specially radars. The most important advantage of FPGA is its parallel nature of executing complicated algorithms. As a result, the received data flow will be processed in a real time manner, which is suitable for radar applications. This paper attempts to show the design and the FPGA implementation of a binary phase-coded pulse compression radar signal generator and processor, that are intended to determine the ranges, and the speeds of targets with small radar cross-section area like drones. The system operating waveform is a bi-phase sequence, that is known to have the best known peak sidelobe level compared to compound Barker codes of the same length. In addition, the design incorporates a range sidelobes cancellation method to remove the time sidelobes in the matched filter output. Also, we are going to represent and investigate the FPGA implementing steps of the radar waveform generator and processor according to the required parameters. Finally, the implementation results of the proposed system will be represented.
Modelling of grid-following current-controlled VSC
Authors: Saad E , Helmy S , Elkoteshy Y , Abouzayed U
Published: December 2023

The voltage sourced converter (VSC) is a basic element in the grid connected solar-PV system that used in converting the DC-generated power from the solar-PV to AC power compatible with the utility grid. In this paper, a grid connected, three phase, two level VSC model and its control technique are simulated. The switched model of a three phase, two level VSC with active and reactive power controller is employed. The VSC’s control is performed based on the grid following VSC methodology. In order to control the transferred active and reactive power between the VSC and the grid, a current control mode (CCM) in dq0 frame is used and discussed in the following sections. The mathematical models of all elements of control loops are developed. Furthermore, the design of these control components is presented with their performance curves using PSCAD/EMTDC software.
CRB-based comparative study of array signal processing direction finding methods supported with SDR platform implementation
Authors: Elkasrawi O A , Abdelaziz A M , AbouBakr H E , Aboelazm M A
Published: December 2023

Radio Direction-Finding (DF) is an extremely important process in numerous commercial and military applications. Array signal processing-based DF methods have been developed to improve estimation performance in recent applications that require higher resolution and accuracy. Practically, angle of arrival (AOA) estimation is challenging due to various intrinsic and extrinsic parameters that affect the results. Therefore, clarifying these parameters and researching their impact on various DF methods are considered important research topics. The Cramer-Rao Bound (CRB) for estimating AOA is calculated based on a model of a linear antenna array system. This bound identify the factors that significantly impact the estimation performance. The current study conducts a comparative analysis of the most widely used array-signal-processing-based direction-finding (DF) methods under different conditions of the CRB parameters. According to the simulation results, Multiple Signal Classification (MUSIC) AOA estimator provides more accurate and stable results. Accordingly, it is chosen for implementation using a prototype testbed based on Software Defined Radio (SDR) technology using National Instruments Universal Software Radio Peripheral (NI-USRP) platform version 2930. Experimental outcomes were tested at various AOA values. The appendix includes the complete derivation for the CRB relation applied on the system model.
Low-complexity joint transmit diversity and adaptive modulation schemes for OGS-satellite FSO uplink
Authors: Elsaidy E , Rakia T , Abdelaziz M , Abd El-azeem M H
Published: December 2023

In this paper, we present two novel low-complexity transmission schemes for optical ground station (OGS)-satellite free space optical (FSO) uplink. Specifically, the TCAM-scheme which is a joint dual-branch threshold combining and adaptive modulation scheme and the SCAM-scheme which is a joint dual-branch selection combining and adaptive modulation scheme. In both schemes, the data rate is adjusted according to the instantaneous received combined SNRs at the satellite. We analyze the performance of the proposed schemes in terms of the outage probability, the average spectral efficiency and average bit error rate, while considering both subcarrirer intensity modulation/direct detection (SIM/DD) and coherent FSO detection techniques. Numerical results show that both TCAM and SCAM schemes provide better performance as compared to a single FSO uplink, while SCAM scheme enjoys better performance than TCAM scheme. This comes at the expense of increased complexity of the SCAM scheme. Also, coherent FSO detection technique shows better performance than the SIM/DD FSO detection technique for both schemes. The choice of which scheme and which FSO detection technique to use is a compromise of required quality of service and complexity.
Optimizing SIFT algorithm parameters for better matching UAV and satellite images
Authors: Elorabi K A , Zekry A , Mohamed WA
Published: December 2023

Image registration has been increasingly employed in various applications such as target identification, 3D mapping, and motion tracking. The main idea of Image registration is aligning two or more images of the same scene captured from different viewpoints, at different times. Scale-invariant feature transform, SIFT, is considered one of the most robust algorithms used in image registration for extracting and matching features under different conditions. Using SIFT algorithm default parameters in Matching UAV and satellite Images provides unreliable results due to the nature of aerial images because the dynamic range is quite low. The number of extracted features depends on the image content and the selected parameters. In this paper we tuned SIFT parameters to get the best performance with aerial images, to increase the number of features (SM) and the correct match rate (CMR) which increases the efficiency of the process of registration. The algorithm is validated by matching a large number of aerial images taken by mini-UAV with satellite images for the same region.
Experimental investigation of a hybrid steel truss reinforced concrete beam for aerospace shelters
Authors: Lofty E A , Kamal I M , Hassan M A , Hassan K M
Published: December 2023

This paper illustrates experimentally the significance of using hybrid steel truss reinforced concrete beam (HSTRCB) in the construction of aerospace shelters. A finite element analysis was carried out in a previous stage to compare the flexural behaviour of HSTRCB with steel truss beams (without concrete casting) and traditional reinforced concrete beams. The Finite element simulations showed a significant improvement in the flexural behaviour of the HSTRCB. In this paper two beams were tested by 4-point bending test. The first is standard reinforced concrete beam. The other is HSTRCB with steel angles as top and bottom reinforcement. Stirrups were replaced by vertical steel plates. Flexural behaviour was represented by the load-deflection curves. Results showed that the adhesion strength between steel truss members and concrete should be enhanced. Failure occurred due to slippage between steel truss elements and concrete. Moreover, HSTRCB showed a noticeable improvement in the ductile behaviour for the zone after the ultimate capacity.
3D Printed Proto Type Model of Pelton Turbine Runner
Authors: Shah H A , Chaudhari G C , Dhiman V D
Published: December 2023

Nowadays, different methods are used in the renewable energy sector for the fabrication of prime movers. A broad classification of the latest additive manufacturing technologies is discussed with ten different parameters like material used, speed, part size, accuracy, application, surface finish, complexity, costing, strength and weakness. Additive manufacturing or 3D printing is also referred to as digital manufacturing technology. 3D printing technology creates physical objects from a geometrical representation by successive addition of materials. Polylactic acid material will be cost-effective to develop the laboratory scale prototype Pelton turbine model. The fused deposition method gives durable products with plastic filament material. FDM provides an optimum condition for the manufacturing of curved surfaces. A step by step process is emphasis for the digital printing of 3D Pelton buckets, runner and shaft. Difficulties associated with the orientation of the Pelton bucket is overcome by using mechanical support structures.
Numerical Analysis of Traditional and Hooped Pelton Runner at Various Operating Conditions
Authors: Karna Aaditya , Chitrakar Sailesh , Bhurtel Mausam , Baral Bivek , Solemslie Bjørn W
Published: December 2023

Pelton turbine is an impulse turbine that converts kinetic energy of incoming jet of water into mechanical energy. Due to impingement of high-speed jet on buckets, Pelton turbine experience high stress at the tip of bucket and at the connection of bucket and rim. To provide the structural strength to the runner, a hoop is attached to it which allows better distribution of forces. However, the impact of hoop on the hydraulic performance of runner is important to assess. For this, a numerical analysis based on Computational Fluid Dynamics has been performed on both traditional and hooped Pelton runner. Transient analysis has been done to calculate the efficiency of both runners under same boundary conditions. The analysis was performed at different openings of needle. Numerical study showed that the efficiency of hooped Pelton runner is less compared to traditional Pelton runner at higher and medium openings. However, at lower openings hooped runner is more efficient. The efficiency drop was in the range of 3.56% to 1.25%. Flow contours reveal that obstruction of fluid is more prominent at higher opening than lower openings, which is the main reason for efficiency drop. Hoop, despite giving structural strength to the runner, is detrimental to the hydraulic performance of traditional runner.