bluuebunny/crossref_metadata_2025 huggingface dataset:
Energetic performance of a smart neighborhood of existing multifamily buildings with heat pumps, PV and CHP focusing on energy balance and CO2 emissions
Authors: Kropp M , Metz J , Lämmle M
Published: December 2023

A smart energy concept was designed and implemented for a cluster of 5 existing multi-family houses, which combines heat pumps, photovoltaic (PV) modules and combined heat and power units (CHP) to achieve energy- and cost-efficient operation. Measurement results of the first year of operation show that the local power generation by PV modules and CHP unit has a positive effect on the electrical self-sufficiency by reducing electricity import from the grid. In winter, when the CHP unit operates continuously for long periods, the entire electricity for the heat pump and 91 % of the total electricity demand of the neighborhood are supplied locally. In summer, only 53 % is generated within the neighborhood. The use of a specifically developed energy management system EMS is intended to further increase this share. CO2 emissions for heating and electricity of the neighborhood are evaluated and amount to 18.4 kg/(m2a). Compared to the previous energy system consisting of gas boilers (29.1 kg/(m2a)), savings of 37 % are achieved with electricity consumption from the grid being reduced by 65 %. In the second construction stage, an additional heat pump, CHP unit and PV modules will be added. The measurement results indicate that the final district energy system is likely to achieve the ambitious CO2 reduction goal of -50% and further increase the self-sufficiency of the district.
National building stock model for evaluating the impact of different retrofit measures
Authors: Vulic N , Eggimann S , Sulzer M , Orehounig K
Published: December 2023

In this study, a methodology was developed to evaluate different retrofit strategies, which allows an estimation of the current and future thermal space heating demand of the approximately 1.8 million residential buildings in Switzerland. The approach is based on a building stock dynamics model that considers new buildings, replacement buildings, demolitions, as well as past and current rates of energy-related retrofits. Different potential retrofit strategies are applied to evaluate their impact on reducing space heating demand. The results show the effectiveness of the distinct retrofit strategies in reaching the target reduction and emphasize the differences in the resulting annual retrofit rates. The simulated specific retrofit rates can serve as a basis for developing building retrofit measures at the national level, as well as for informing the next generation of regulations.
Performance measurements on WISC collectors under artificial environmental conditions
Authors: Pauletta S , Duret A , Dupont G , Jobard X
Published: December 2023

In the framework of the TriSolHP project, aimed at estimating the impact of improved heat pump technologies for decarbonization of non-retrofitted multifamily buildings in urban districts, a new type of PVT WISC (a photovoltaic-thermal wind and/or infrared sensitive collector) has been extensively tested in a climatic room without light input. The measurement campaign focused on the impact of airflow over the collector heat transfer coefficient for different installation layouts and when covered in ice. Measurement data were compared to TRNSYS simulations to gain an insight over the uncertainties affecting the performance models available in literature for this type of WISC.
Value stacking flexibility services in neighborhoods participating in fast frequency reserve markets
Authors: Stai Peter , Bjarghov Sigurd , Thorvaldsen Kasper E. , Backe Stian
Published: December 2023

Neighborhoods are responsible for considerable amounts of the total energy demand in Europe, and increased shares of variable renewable energy sources will require energy balancing services. Local flexibility resources in neighborhoods can help provide this. However, there is a lack of insight into the economic incentives and operational consequences for property owners to adopt prosumer qualities. Using a linear program that minimizes total electricity costs, this paper evaluates annual cost savings for a Norwegian university campus when value stacking the following flexibility services: responding to electricity spot prices, grid tariffs, and provision of fast frequency reserve (FFR). Several flexibility resources are addressed in this study, including a stationary battery, electric vehicle charging stations, and a vehicle-to-grid charging station. The results found an average 6.8% yearly cost decrease by FFR participation, supporting the notion that there is a significant economic potential in applying flexible resources from prosumers in fast frequency reserve markets, without significant conflicts with other flexibility services.
Using Machine Learning to Predict Window Opening Position in a Naturally Ventilated Building
Authors: Wong J. , Donges J. , Gasparella A. , Rysanek A.
Published: December 2023

Advancements in machine learning have faciliated its use in many domains. In this work we apply it to building sector, where mechanical ventilation systems are prevalent. While natural ventilation still can be suitable in many situations, the difficulty in estimating airflows and long computational simulation times prevents its adoption. Since ventilation rate depends heavily on window opening angle, we employ a computer vision techniques to estimate the states. We train a Fully-Connected Neural Network on images of European-style tilt-and-turn windows set at discrete positions, achieving over 95% average F1-Score. We highlight potential drawbacks with the method and identify steps forward on the path to real-world implementation.
Comparison of different coupling variants for building and HVAC simulation
Authors: Huang C , Eckstädt E
Published: December 2023

Coupled building and HVAC simulations applying the FMI standard promise many advantages in terms of system design and optimisation. In this paper, a systematic analysis of possible options for such couplings is presented. For one of these options, a case study is carried out where a quantitative comparison between the uncoupled reference system and the corresponding coupled system with different communication step sizes is carried out. Based on the simulation results, recommendations and challenges for such couplings are derived. In particular, the correlation between the communication step size of the FMUs and the computing time, as well as the deviations of the simulation results compared to the results of an uncoupled simulation are analysed.
Comparison of two deep reinforcement learning algorithms towards an optimal policy for smart building thermal control
Authors: Silvestri Alberto , Coraci Davide , Wu Duan , Borkowski Esther , Schlueter Arno
Published: December 2023

Heating, Ventilation, and Air Conditioning (HVAC) systems are the main providers of occupant comfort, and at the same time, they represent a significant source of energy consumption. Improving their efficiency is essential for reducing the environmental impact of buildings. However, traditional rule-based and model-based strategies are often inefficient in real-world applications due to the complex building thermal dynamics and the influence of heterogeneous disturbances, such as unpredictable occupant behavior. In order to address this issue, the performance of two state-of-the-art model-free Deep Reinforcement Learning (DRL) algorithms, Proximal Policy Optimization (PPO) and Soft Actor-Critic (SAC), has been compared when the percentage valve opening is managed in a thermally activated building system, modeled in a simulated environment from data collected in an existing office building in Switzerland. Results show that PPO reduced energy costs by 18% and decreased temperature violations by 33%, while SAC achieved a 14% reduction in energy costs and 64% fewer temperature violations compared to the onsite Rule-Based Controller (RBC).
Flexibility implications of optimal PV design: building vs. community scale
Authors: Li Q , Vulic N , Cai H , Heer P
Published: December 2023

The Swiss Energy Strategy 2050 aims for a significant increase in renewable energy generation, with photovoltaic (PV) energy having the largest share. Such development challenges the balance between electricity supply and demand, which can be partly mitigated through optimized PV integration together with energy storage systems. This study investigates the optimal placement of rooftop and façade PV for a small energy community considering investment and operational costs, embodied and operational emissions, and financial and environmental benefits of excess on-site electricity production, as well as batteries and different heating system options. Additionally, a methodology is developed to quantify energy flexibility needs at both the building and community scale. A case study neighborhood, comprising three single-family and two multi-family homes is optimized across different scenarios. Results show that when individual self-consumption is considered, installing an air-to-water heat pump system with a heating buffer tank allows for smaller PV systems with better grid interaction conditions. When collective self-consumption is considered, an overall reduction in PV system size is observed, contributing to reduced energy flexibility needs by effectively lowering peak feed-in power and improving the match between on-site PV production and demand.
The GENEAP project: digitalising and automating planning of district heating and cooling
Authors: Chambers Jonathan , Cozza Stefano , Patel Martin
Published: December 2023

The Swiss Energy Strategy 2050 implies a transformation of the provision of thermal energy services (heating and cooling) to become CO2 neutral, district heating and cooling (DHC) are an important solution, which is technically challenging to design and whose implementation entails certain risks for investment. The GENEAP (Geospatial Analysis and Planning) project developed a software that applies automation and digitalisation to address this barrier and to apply scientific research to support the work of practitioners. The software Thermal Energy System Simulation Assistant (TESSA) increases reproducibility and decreases errors, and thereby reducing overall costs. We introduced innovative algorithms for modelling heat and cooling demand, thermal energy supplies, and the cost of thermal network technologies under different retrofit and climate change scenarios. We developed graph theory-based algorithms for computationally efficient routing of thermal network pipes. The goal of the GENEAP project was to validate the models and to establish how practitioners would find value in such a tool. Through workshops and interviews we established the need for digital tools due to the rapidly increasing need for new projects, the complexity and long time frames of projects, and the limited number of available experts to do this work. We found a gap between the high level energy strategy (Plan Directeur Energetique) and the detailed engineering design stage. In between these two stages we find the need for a flexible approach that can integrate cities and societies needs into the engineering design with non-energy requirements (e.g. political context, urban constraints and opportunities, etc).
The more the better? Archetype segmentation in urban building energy modelling
Authors: Le Hong Z , Berzolla Z , Reinhart C
Published: December 2023

Urban building energy modelling is gaining traction as a planning tool to support widespread decarbonization of the built environment. Building-scale models allow for the evaluation of specific emission reduction policies at an urban scale. Given the limited availability of building-by-building data on construction standard and program, aggregating building information through archetypes is key, but a poorly understood step in the urban energy modelling process. In this study, different levels of archetype segmentation are explored for the city of Oshkosh, WI (∼13,000 buildings). A comparison of actual, city-level energy with UBEM simulations suggests higher levels of archetype segmentation do not necessarily lead to higher accuracy, leading to models that are both accurate and nimble enough to explore a variety of upgrade scenarios. Informing archetypal segmentation with policy-informed metrics is beneficial, but pursuing increased detail could dangerously reduce accuracy without ground-truth data.
Automatic detection of control loops in existing buildings
Authors: Stinner Florian , Gorgis David , Kümpel Alexander , Müller Dirk
Published: December 2023

Improving control loops in buildings is cost-intensive due to the need of expert time. With well structured data, the development of data-driven algorithms is promising to minimize the required time. But data stream names across buildings do not follow a uniform naming schema.

We developed a method to identify temperature control loops (sensors and set points) based on data stream names. The methodology starts with narrowing down to three potential sensors per set point using string distances and their combination, before estimating the probability that the first sensor is the correct paired sensor to the set point. We used data from three buildings: A large data set composed of over 12,000 translated data streams for the development and adjustment of the methodology and two smaller data sets for the verification of the transferability of the developed method.

The results are strongly dependent on data stream name structure. The results indicate that within the test data set, the pairing sensor to a set point can be automatically limited to three or five sensor candidates, and the algorithm can identify a high number of control loops. For the transfer to the two validation sets, the limitation of sensor candidates is still possible, but identifying pairings and control loops is difficult.
Planning the Design and Operation of Urban Energy Systems with Limited Data Availability: A Holistic Open-Source Tool Chain
Authors: Schreiber T , Beckhölter T , Derzsi K , Droste K , Karuvingal R , Nie Y , Wackerbauer D , Wirtz M , Welter S , Zhang Y , Müller D
Published: December 2023

Urban energy systems are becoming more complex due to the integration of renewable energy sources and electrification of heat supply. Dynamic planning and operation strategies are necessary to optimally satisfy energy demands, especially in the 5th generation of heating and cooling networks, which efficiently address these challenges through decentralized water-water heat pumps. An end-to-end tool chain is presented which enables to analyze and evaluate such systems in early planning phases with limited data availability. It includes thermal building simulations, heating network simulations, optimization, and incorporation capabilities for model-based operation algorithms and AI-based forecasting algorithms. User acceptance of the energy system can also be considered in the design phase in future. This paper presents the interaction of the open-source tools: TEASER, which generates high-resolution time-series of heating and cooling demands of buildings; uesgraphs, which generates and simulates thermal networks from geodata; and EHDO, which optimizes energy hub designs. Future research pathways include integrating AI-based operation optimization and surveys to support user feedback integration. Work will also address substation models for the 5th generation heating networks and novel data infrastructures. The tool chain has already been successfully used in many scenarios, but open questions remain around integrating the methods into the operation phase and further developing the complex energy models the tool chain is built upon.
Review of natural language processing techniques for characterizing positive energy districts
Authors: Han Mengjie , Shah Juveria , Zhang Xingxing
Published: December 2023

The concept of Positive Energy Districts (PEDs) has emerged as a crucial aspect of endeavours aimed at accelerating the transition to zero carbon emissions and climate-neutral living spaces. The focus of research has shifted from energy-efficient individual buildings to entire districts, where the objective is to achieve a positive energy balance over a specific timeframe. The consensus on the conceptualization of a PED has been evolving and a standardized checklist for identifying and evaluating its constituent elements needs to be addressed. This study aims to develop a methodology for characterizing PEDs by leveraging natural language processing (NLP) techniques to model, extract, and map these elements. Furthermore, a review of state-of-the-art research papers is conducted to ascertain their contribution to assessing the effectiveness of NLP models. The findings indicate that NLP holds significant potential in modelling the majority of the identified elements across various domains. To establish a systematic framework for AI modelling, it is crucial to adopt approaches that integrate established and innovative techniques for PED characterization. Such an approach would enable a comprehensive and effective implementation of NLP within the context of PEDs, facilitating the creation of sustainable and resilient urban environments.
Heat vulnerability digital mapping at neighbourhood level in the compact city
Authors: Morganti M , Lopez-Ordoñez C , Ciardiello A
Published: December 2023

This paper analyses the impact of urban form and vegetation on one of the most significant parameters that affect people’s thermal comfort and an indicator of urban heat vulnerability: the mean radiant temperature (MRT). To obtain spatialized results and understand in detail the current thermal situation of different public spaces that are part of the city, we combined the SOLWEIG calculation model included in the UMEP tool for QGIS with Urban Weather Generator for Rhino. Six neighbourhoods of Rome (IT) and the associated areas with typical compact urban forms, ranging from historical centre to modern suburbs, have been analysed in the warmest week of the year (August 03-09) during the most critical hours of the day (10 a.m. - 4 p.m.). Georeferenced maps with the mean values of MRT for the studied period allow us to analyse the thermal behaviour of each public square and neighbourhood and locate possible urban havens during heatwaves. This study is part of a larger work that seeks to define a more accurate approach to quantify heat vulnerability within the urban vulnerability indexes, in light of the climate crisis facing cities.
Assessing outdoor comfort near graduation towers: An experimental calibration study in a public open space
Authors: Görgen F , Rossi-Schwarzenbeck M
Published: December 2023

This study focuses on the experimental calibration of a numerical model to quantify the cooling effects of graduation towers under heat wave conditions. Given the increasing number of hot days, tropical nights and ongoing urbanization, simulation tools for predicting and enhancing outdoor comfort have become increasingly important. To investigate the influence of the water mist emitted by the graduation towers, a 3D model was constructed using the microclimate simulation tool ENVI-met and calibrated against in-situ measurements. By means of evaporation, both air temperature and PET (Physiological Equivalent Temperature) could be reduced by up to 14.8K and 9.5K, respectively, resulting in no thermal stress in the vicinity of the graduation towers. The calibrated model can assist municipalities in assessing the cooling performance of graduation towers, enabling them to adjust water usage according to weather conditions and enhance outdoor comfort for the well-being of the population in recreational areas.
Experimental study to understand the thermal environment of an office cooled by radiant ceiling panels and dedicated outdoor air system
Authors: Chen K W , Izuhara I , Merchant C , Meggers F , Pantelic J
Published: December 2023

This research aims to better understand the radiant environment of an interior space located in the tropical climate that is cooled by Radiant Ceiling Panels (RCPs). To do so, we have designed a highly instrumented 177m2 office testbed in Singapore installed with RCPs, Dedicated Outdoor Air System (DOAS) and Fan Coil Units (FCUs). An 11-day experiment is designed to monitor the radiant environment when being cooled by 1) RCPs + DOAS and 2) FCUs + DOAS with a fixed internal load of 2kW and humidity load of 8g/hr. We alternate between these two cooling modes, with variations in panels’ water supply temperature and window blinds. We expect to see a separation of Mean Radiant Temperature (MRT) and air temperature in mode 1 with the use of improved radiant sensors. However, results showed only minor differences in the radiant environment between the two modes of cooling. There was no significant MRT and air temperature separation (<1°C). These insights provide a better understanding of our radiant environment, which can potentially improve the way we control radiant systems. With better understanding, we can support high thermal comfort performance of a radiant systems as compared to a more common air-based system.
Personal comfort models in long-term monitoring using physiological data from wearable sensors
Authors: Martins Gnecco V , Pigliautile I , Pisello A L
Published: December 2023

Personal Comfort Models (PCMs) propose a new approach for human-centric comfort studies overcoming the one-size-fits-all of the conventional models. This research addresses the development of PCMs based on a seven-month long-term monitoring campaign including continuous environmental and physiological data collection through wearables and daily survey submission about subjects’ sensations. To tackle the influence of subjects’ environmental exposure history, time series of environmental data of different durations were used to predict individuals’ perception via Machine Learning models with Support Vector Machine and Random Forest methods. The accuracy and F1-score values of seven different PCMs were confronted for each subject and for the whole group (nine people). The number of datapoints per subject and their answers’ consistency during time affected the models’ accuracy, and the inclusion of physiological signals improved the models’ performance. When considering the whole dataset, the comfort model accuracy decreases supporting that individual subjectivity have an important impact in the environmental perception prediction.
Exploratory analysis of the operation of a MHRV system in an overheating nZEB apartment in Spain
Authors: Otaegi Jorge , Martín-Garín Alexander , Hernández-Minguillón Rufino J. , Rodríguez-Vidal Iñigo
Published: December 2023

This article investigates the operation of a Mechanical Heat Recovery Ventilation (MHRV) system in an overheating nZEB apartment in Spain. The building, an apartment tower, was found to have a moderate to severe issue of overheating during extensive parts of the year. The study focuses on a flat located on the top floor of the Bolueta tower I in Bilbao, Spain, which is the world’s tallest Passivhaus building. Temperature and relative humidity data loggers were placed in various locations inside and outside the flat, as well as an amperemeter to monitor the operating regime of the MHRV unit’s fans. The study covered a period of 18 months and consisted in an exploratory analysis of the data obtained. The results show that the dwelling and its ventilation system partially correspond to the expected performance during the cold season but deviate from the usual design assumptions considered for the warm periods. The MHRV unit may have difficulties entering bypass mode and providing sufficient free cooling to maintain adequate indoor temperatures due to its placement. These findings provide insight into the thermal performance of the building and operation of the MHRV system and can inform future research.
Indoor environmental quality trade-offs due to summertime natural ventilation in London care homes
Authors: Tsoulou I , Jain N , Oikonomou E , Petrou G , Mavrogianni A , Gupta R , Howard A , Milojevic A , Davies M
Published: December 2023

We evaluate current and future summertime temperature and indoor air quality (IAQ) in two London care homes, occupied by seniors. We further examine the effect of natural ventilation, aiming to identify strategies that can maintain temperature, CO2 and key pollutants (PM2.5, NO2) within acceptable ranges. Data come from simulations in DesignBuilder. Results show a higher risk of overheating in the newer care home, with 85% of hourly outputs exceeding 26°C. In addition, bedrooms are much warmer than lounges in both homes, with averages expected to reach 32-35°C by 2050. In terms of IAQ, 65% of PM2.5 and NO2 hourly outputs are within range; however, without any ventilation, the high CO2 levels are expected to rise by 70-130ppm in 2050, especially in bedrooms of the newer home. Results further indicate that natural ventilation can substantially reduce temperature and CO2, but at the same time it may increase PM2.5 and NO2 coming from outdoors. Yet, these trade-offs can be reduced through a careful ventilation strategy that considers building-specific characteristics, as well as time of day and duration. Findings suggest a need to focus on the interdependencies among indoor environmental quality outputs and highlight the value of inexpensive and sustainable passive ventilation.
Thermal perception and satisfaction of Italian students in distance (home) learning vs face-to-face learning environments during the heating season
Authors: Pittana Ilaria , Morandi Federica , Cappelletti Francesca , Gasparella Andrea , Tzempelikos Athanasios
Published: December 2023

During the 2020-2021 COVID-19 pandemic situation, millions of high school students in Italy had to adapt a room in their home for partial distance learning. This paper investigates the thermal perception and satisfaction with the thermal conditions expressed by 45 teenage students alternating between Distance Learning (DL) and Face-to-face learning (FL) during that period. Students completed questionnaires about their perception and satisfaction with the thermal environment while air temperature and humidity were monitored for 14 weeks. The thermal conditions in the classrooms, where students attended classes every other day, were also monitored during this time. The results show that students at home experienced a high percentage of time with conditions outside recommended comfort limits. Nevertheless, most of the students expressed a TSV equal to 0. In addition, the proposed long-term thermal discomfort indicators, such as running mean of the indoor air temperature, correlated rather poorly with subjective votes. This may indicate that different indices should be considered when analyzing mid-term subjective thermal comfort evaluations.
Energy performance of ventilated façades; the influence of the colour and the air channel dimension
Authors: Roig O , Pardal C , Isalgue A , Paricio I
Published: December 2023

Due to the current climate crisis, there is an urgent need to reduce greenhouse gas emissions. Improving façades’ energy performance can significantly reduce the cooling and heating demand of a building. More and more, in warm and mild climates, ventilated façade are given the function of avoiding overheating due to solar radiation and thus reducing the cooling demand of the building. However, this system’s energy performance is not easy to estimate. This study aims to assess the influence of some defining parameters of the ventilated façade on its energy performance. These parameters are not considered in the usual evaluation systems and can be relevant to the envelope’s energy performance. A calculation system has been developed so that architects can use it during the design process to know how their design decisions influence energy performance. Once validated with comparisons with measured values, the calculation system is applied to analyse the influence of some defining parameters of the façade during a warm day in Barcelona: the outer surface’s colour and the dimensions of the ventilation channel. For the studied cases, the change of these parameters implies an important variation in the daily average energy flow traversing the façade. In some cases, it even reverses the direction of the flow, changing from heat gains to heat losses. This concludes that these parameters are relevant to the energy performance of the ventilated façade and that the developed calculation system is a suitable tool to compute it.
Development of a composite model for predicting urban surface temperature distribution in the context of GIS
Authors: Cui Ziang , Leduc Thomas , Rodler Auline , Musy Marjorie
Published: December 2023

In this paper, we present a new model for simulating radiation heat transfer and surface temperatures in urban environments, which is a prerequisite for simulating outdoor mean radiant temperature for pedestrians. We propose a new model whose novelty lies in a new algorithm for simulating diffuse radiation by combining the Nusselt unit sphere method and Monte Carlo ray tracing algorithm. This combined use of different methods is automatically activated depending on the complexity of the scene and, in particular, the arrangement of the facets facing each other. The model is implemented in a Python-based tool, t4gpd, which combines the capabilities of geographic information science and related technologies (GIS &T) with efficient ray-casting solutions. The model is tested on a theoretical mock-up of nine virtual buildings in Nantes under summer and winter weather conditions and compared with SOLENE-Microclimat results. The view factor and solar radiation flux simulation results agree well with the reference solution, with a significant reduction in simulation computation time. However, the model has limitations due to the exclusion of vegetation evapotranspiration characteristics, wind profile model, and soil with complete stratigraphy. Overall, this new model provides an efficient tool for simulating outdoor pedestrian thermal comfort in urban environments and has potential for further development and validation.
Occupant-centric metadata paradigms for comfort optimization in buildings
Authors: Bradford Kipp , Coleman James , Meggers Forrest
Published: December 2023

Three decades of building performance standards have resulted in a meaningful reduction in energy consumption in commercial buildings, but limited improvement in thermal comfort has been observed. ASHRAE Standard 55, the primary reference used to design and operate “comfortable” buildings, specifies six thermodynamic factors that must be addressed to provide comfort in a space. In practice, survey data reports only a small percentage of buildings are considered satisfactory by occupants. We perform a literature review to demonstrate that the range of each of the six thermodynamic dimensions of comfort can be observed well outside of the applicability of ASHRAE 55 in real buildings. The typical practice of modulating air temperature (Ta
) is shown to result in frequent occupant dissatisfaction. We posit that to be able to more consistently operate within a given “comfort zone” in a wider range of thermodynamic environments, we must embed within building systems higher-dimensional, occupant-centric parameters. To understand if two popular metadata schemas, Project Haystack and Brick Schema, are equipped to support higher-dimensional control paradigms, we (1) define a model, measure, manipulate (M3) evaluation criteria, which we (2) apply to each of the above schemas to determine if they can be used to codify closed-loop control for a given set of thermodynamic dimensions of comfort. We conclude that recent extensions to the Brick Schema provide much of the background necessary to codify closed control loops in six dimensions, and that Project Haystack requires a greater expansion.
Binder jetting additive manufacturing comparative study
Authors: Abdelkhalek S
Published: December 2023

This comparative study aims to analyze the most relevant literature regarding Binder Jetting Additive Manufacturing (BJAM) process. The paper starts with section one to briefly introduce the process. Section two of the paper presents an overview of the technology; the main advantages and shortcomings are also addressed. Then, the materials that are mostly employed in BJ are introduced. In section four, the most important design considerations that must be taken into account in this process are presented. Section five of the paper compares the BJ systems available nowadays. Some relevant examples of components and geometries that can be created with this technology are presented next with special emphasis on applications for high-tech industries. Then, the main challenges and limitations along with the prospects of the BJ process are discussed. Finally, the main conclusions extracted from the literature review conducted are listed.
Numerical study of airfoil used for helicopter rotor tip to investigate the enhancement in the aerodynamic characteristics using active flow control at forward flight conditions
Authors: Tawfik T M , Abdelrahman M M
Published: December 2023

Helicopter forward flight is the most important state of flight due to time spent in this mode during the complete helicopter trip. In this study, a main rotor blade tip airfoil was simulated to obtain the effect of applying active flow control on the tip part of the rotor blade. A blowing excitation jet is applied to the leading edge of the airfoil just before the separation point with small momentum and high frequency to enhance the near wall boundary layer characteristic. This jet is used with different amplitude, frequency and excitation location from a leading edge to study the effect of this parameter. A numerical model is used to solve two different angles of attack and all results are compared with NACA report that used the same helicopter hub and airfoil. Results show good agreement with the experimental results and the chosen excitation parameter gives good enhancement to the performance of the airfoil used in the tip part of the helicopter blade in this mode of flight. Performance represented in lift and drag and lift to drag ratio shows improvement, reaching about 10% increase in lift and 30% decrease in drag, which means more than 50% change in lift to drag ratio. Furthermore, this study gives a good estimation of the best excitation location that is required for real application on the helicopter blade to improve of forward flight performance.
Multidisciplinary conceptual investigation for integrating stores, not in the original configuration of a subsonic airplane
Authors: Morad Alaa M
Published: December 2023

Subsonic airplanes are widely used around the world in applications such as pilot training, transportation, sports activities, insect fighting, and field monitoring. This research deals with airplanes that already own the capability of carrying suspended loads. Increasing the airplane’s capabilities and configurations by integrating different suspended loads like smaller or larger external fuel tanks or insecticide tanks that are not in the original configuration of the airplane is a great advantage. This modification can be done without dramatic changes to the airplane and with minimum cost. In this research, a multidisciplinary methodology is used to integrate a commercially-available premade external fuel tank into the Embraer E312 Tucano airplane which is not in the original configuration of the airplane. First, a geometrical analysis is performed to ensure the availability of proper installation. This study leads to the design of an adaptor between the tank and the airplane pylon, then, a computational fluid dynamics (CFD) modeling using ANSYS-CFX is performed to evaluate aerodynamic forces and moments applied on the new fuel tank. Furthermore, finite element modeling using ANSYS-Static structure is performed by applying the aerodynamic and inertial loads to calculate the adaptor’s stresses and structure safety factor. Finally, vibration fatigue analysis-based power spectral densities are developed using ANSYS-Random vibration to calculate the adaptor’s estimated lifetime to ensure the store system’s safety by applying airplane vibration acceleration spectral density pattern selected from applicable standard. In this typical example, the above-mentioned methodology is applied and the results are acceptable.
Improving performance of pump-controlled hydraulic circuits for single-rod actuators: conceptual study
Authors: Imam A , Tolba M S , Sepehri N
Published: December 2023

Pump-controlled hydraulic circuits are more efficient than conventional valve-controlled ones. Pump-controlled hydraulic circuits for double rod cylinders are well developed and, presently, implemented in many applications including aviation. Nevertheless, current pump-controlled hydraulic circuits for single-rod cylinders encounter performance issues during specific operating conditions. Pressure and actuator velocity oscillations are encountered when operating in this critical zone. Different concepts, techniques and designs are proposed by researchers to overcome such vibration issues. In this research, three different concepts to overcome the reported oscillation problem in these circuits are presented; namely: (1) shifting of critical zone into lower loading ranges, (2) applying selective leakage, and (3) applying selective throttling. Simulation studies indicated that the new concepts alleviated the oscillation issue of the common pump-controlled circuits, and improved their performances. The second and third concepts, in particular, were capable of eliminating the whole critical zone. The first concept reduced the area of the critical zone in the load-velocity plane and lessened undesirable effect of oscillations. Simulation studies further proved the enhanced performance of circuits that applies these concepts as compared to previously-designed circuits.
Adaptive dynamic kalman filter for high-performance tilt-angles estimation
Authors: Badawy A A , Abozied M A H , Hassaballa A H , Elhalwagy Y Z
Published: December 2023

Estimation of attitude is a potential task for autonomous vehicles as it directly affects the velocity and position estimates as well as the overall system autonomy. The estimation of attitude angles utilizing gyro measurements always suffers from increasing drift with time. Although accelerometer measurements can provide an absolute estimate of pitch and roll angles for static and low dynamics conditions, they have two drawbacks the effect of additional external acceleration and the inability to capture the high dynamics motion. In this paper, an adaptive Kalman filter (AKF) is utilized for integrating the gyros and accelerometer measurements for enhancing the roll and pitch angles estimates by compensating for the effect of linear acceleration as well as adaptively adapting the Kalman filter measurement covariance matrix. The proposed algorithm is evaluated using real offline measurements for a flying vehicle. Further, a comparative analysis is carried out with the original Kalman filter (KF) algorithm and with the imufilter from Sensor Fusion and Tracking Toolbox from Matlab. The results presented satisfactory performance and enhancement for roll and pitch angles estimate.
Design, modeling, manufacturing, and control of dual axis stabilized system
Authors: Elsepee M M , Roshdy A A , Ali A A , Fayed M A
Published: December 2023

Recently, Inertial Stabilized Systems (ISS) are widely spread either in military or civilian applications. It’s used to stabilize and point the onboard sensors. Therefore, the accurate modeling and control is a crucial factor to design a suitable control system. In this work, two axes gimbal system is designed, modeled, manufactured, and controlled. Firstly, the stabilized system is built using solid work software. Secondly, the system mathematical model is derived for the physical system with its actuators and encoders. Thirdly, the designed model is manufactured and integrated with the suitable motors; the overall open loop system model is implemented in MATLAB (Simulink). Finally, a modified PI-D structure is designed to stabilize the ISS in an efficient manner, the simulation results show the superiority of the designed controller’s performance and robustness compared to the classical PID in transient and steady state responses.
Unified performance parameters for IM/DD techniques over gamma-gamma fading channel with pointing errors
Authors: Roshdy M M , Hassan K M , Elghandour A H
Published: December 2023

In this paper, we discuss the performance of different intensity modulation direct detection techniques (IM-DD) used in free space optical systems (FSO) under different channel impairments such as path loss, atmospheric turbulence, and pointing errors. We derived unified formulas for each of the average symbol error rate (SER) bounds and outage probability for different modulation techniques: OOK, MPPM, and LMPPM. The accuracy of the obtained formulas is validated through comparison with MC-simulation results. Finally, we investigate the effect of system parameters on FSO link performance.
Strength design optimization of sandwich composite structures under heavy dynamic loads
Authors: Osman A , El-Hefni M , Galal K
Published: December 2023

Recent researches have witnessed an increased interest in the Rapid Runway Repair (RRR) methods to rehabilitate damages that may be caused by different incidents, such as: natural disasters of earthquakes, floods or man-made vandalism in civil wars. RRR is a strategic process for airport operations for civil and peace-making missions. The current RRR techniques like precast concrete slabs, metal mats, and fiberglass mats have different pros and cons. The current study numerically investigates CFRP sandwich composite structure for RRR usage, where its strength is maximized by design optimization to reach the possible carrying aircraft wheel capacity and safety factors. The proposed composite structure is advantageous of no corrosion, low erection time, high capacity-to-weight ratio, same finish of runway surface and repaired area, and can be applied over spots of unlevelled or inadequate bearing capacity of 60 cm diameter. The strength of the basic design of composite sandwich structure is first assessed to its maximum allowed carrying aircraft wheel capacity by FE modelling. Secondly, The Genetic Algorithm (GA) optimization technique is applied for maximizing the strength of the composite structure webs satisfying the minimum safety factor of five failure criteria of Tsai-Wu, Tsai-hill, Hoffman, Hashin and maximum stress. Finally, the achieved results promoted the usage of the composite structure to operate at the taxiways, runways, and theoretically, landing and take-off areas.
Using remote sensing technology in estimating flood discharge
Authors: Abdullah A S , Moussa O M , Hassan A A , Tarek M
Published: December 2023

Floods are the most natural disasters occurring on earth. Recently, Egypt has been subjected to more frequent floods due to climate change. The main objective of this paper is creating hydrological analysis and estimating water discharge due to a flood hitting a hazardous zone near Safaga city. The research is divided into four main stages; 1) Morphological study, 2) Meteorological study, 3) Losses estimation, and 4) Flood discharge estimation. First, morphological study in which watershed boundaries, main streams and morphological data are delineated using geographic information system (GIS) with the aid of Landsat-8 satellite images and 30-m resolution digital elevation model (DEM). Second, meteorological study in which conventional rainfall frequency analysis is generated to estimate rainfall depth at different return periods using 15-years rainfall historical data from weather stations. Third, losses estimation is determined by using soil conservation service-curve number method (SCS-CN). Fourth, water discharge volume is carried out through hydrological modelling using a hydrologic engineering centre model. The estimated water volume is an appropriate information for decision makers to propose the adequate protection works to mitigate flood impacts.
Propulsion theoretical and experimental analysis of composite propellants motors
Authors: Said A , Maraden A , Elhedery T M , abd Elall A M , Elbasuney S
Published: December 2023

Rockets have revolutionized space technology and human space exploration. Most rockets and missiles are both propelled by rocket motors that use composite solid propellants. The ICT code and the NSAS CEA code are two programs that can be used to forecast theoretical propulsion parameters for composite solid rocket propellant. Rocket propellant performance is governed by a specific impulse factor, which is calculated theoretical and experiment. In this paper, the theoretical specific impulse for different composite solid propellant formulations at 70 bar combustion pressure and an adapted nozzle (optimum expansion) were calculated by the NASA-CEA code and the ICT code. Meanwhile, a static firing test was performed on a small scale test motor to experimentally determine the actual specific impulse. The objective is to verify theoretical calculations from two codes with experimental data, via the determination of the specific impulse deviation co-efficient.
Governing of a Francis Turbine Model Subjected to Load Variations
Authors: Haugum Jørgen
Published: December 2023

In this work, the problem of mechanical backlash in the governor system for the Francis test rig at the Waterpower Laboratory, NTNU Trondheim, is investigated. Through numerical simulations on a digital model of the test rig, done in the software SIMSEN, the maximum allowable backlash which still enables stable governing was detected. This was done by further developing the model used in the work by A. Ingranata [1], to perform load variation tests presented by Statnett [2]. From these frequency control tests it was concluded that the maximum mechanical backlash which still enables stable governing, is 1% of maximum stroke length of the servomotor present in the governor system. To design a system which can achieve the requirements of 1% backlash, a more conventional layout which utilizes links instead of the slots present in the existing governor ring, is suggested.
A Review on Machine Learning approaches for Himalayan Rock Mass Classification
Authors: Dumaru Jenisha , Karki Sujan , Shrestha Ranjit , Khadka Shyam Sundar
Published: December 2023

Among all of the subsystems and components of hydropower, the tunnel is one of the crucial structures that face most of the pre-operation, real-time and post-operation challenges. Tunnels used as a water conveyance system in the majority of the projects lead to significant importance in the hydropower sector. The engineering rock mass classification is a crucial step in the accomplishment of underground constructions, particularly tunnels and caverns within the rock mass. The quality of rock mass parameters must be assessed and predicted with greater accuracy. However, the difficulties lie in the proper assessment of these parameters to define their quality. Studies have shown that despite the use of numerical and empirical methods in construction practices, numerous problems are reported when it comes to dealing with such structures. Over the years, various approaches based on machine learning (ML) techniques have been used for the minimization of these difficulties. As in recent trends, the development of machine learning technologies is currently bringing new methodologies in assessing rock mass classification. Although, because a sufficiently large database is required for such initiatives, there are a number of difficulties in their practical execution. Thus, a review of studies on the use of machine learning techniques in rock mass classification is presented in this paper. To determine the future directions of ML in RMC, it presents a comprehensive assessment to examine how ML models are being used. This study offers recommendations for creating an industry-specific model focusing on the strengths and weaknesses of ML techniques