bluuebunny/crossref_metadata_2025_split huggingface dataset:
Urban airflow prediction by pix2pix trained on FFD
Authors: Vecchiarelli Rebekah , Kraus Michael , Griego Danielle , Waibel Christoph 
Published: December 2023

Abstract
Existing computer-aided design tools render insufficient in their capacity to enable architects and engineers to efficiently evaluate alternative designs during early design phases due to their computationally expensive nature, which is especially the case for computational fluid dynamics (CFD) methods. One of the greatest bottleneck for integrating CFD analysis into early design phases is the limited potential for parametric analysis, where a number of design alternatives need to be quickly generated and evaluated. In this context, the present study investigates the use of the generative deep learning method “pix2pix”, which leverages conditional generative adversarial networks (cGANs) for image-to-image translation, for prediction of airflow characteristics in different representations. The evaluation proposes statistical metrics to judge the fitness of the approach in performing urban airflow prediction. Our study demonstrates that the proposed method to be implemented, trained and validated successfully for different representations of the flow field prediction under parametric city shapes by incorporating building height and vectorial information (either components or magnitudes) into the pix2pix image inputs. The findings of the study reveal that the vortical flow fields can be predicted with a high accuracy in space and magnitude in all model variations tested. Adding building height information to the input images also significantly improves Kullback-Leibler (KL) divergence compared to using uniform building heights as inputs. Using vectorial information in the form of decomposed u, v, w-vector fields during training enabled pix2pix to additionally generate vectorial predictions instead of magnitudes only.
Economic and environmental benefits of decentralized multi-energy systems for energy communities
Authors: Jobard Xavier , Capezzali Massimiliano , Dimri Neha , Duret Alexis , Fesefeldt Marten , Frossard Mija , Jacquot Vincent , Lasvaux Sebastien 
Published: December 2023

AbstractIn the context of growing interest in decentralised multi energy systems, this work aims at quantifying the benefit of optimized energy concepts for energy communities at the neighbourhood scale compared to individually optimized solution. To tackle this question a multi-objective optimization framework was developed and applied to a case study of 6 buildings consisting of 85% of residential dwellings and 15% to retail shop and food stores. Grouped buildings have decreased costs and greenhouse gases emissions (GHGE) respectively by 18% and 12% in the cost optimum compared to individual buildings. In the environmental optimum, costs have decreased by 11%, while GHGE remains in the same range. This decrease is at both optimum driven by electricity prices favourable to large consumers since exchanges on the electrical microgrid for this neighbourhood is very small. Optimal decrease of GHGE is obtained with greater use of HPs and smaller natural gas consumption. This work illustrates the interest of multi-objective approaches to identify optimal energy solutions for groups of buildings.
Developing tools for municipalities to meet carbon targets
Authors: Lari Khosro , Cant Kevin , Evins Ralph 
Published: December 2023

Abstract
Carbon emissions must be cut in half by 2030 to meet the Paris Agreement’s goals, and cities and municipalities are at the forefront of the fight against climate change. In 2017, the energy use of buildings directly accounted for 51% of emissions in the City of Victoria and offered the greatest opportunity for the municipal government to act. Unfortunately, at this point, many cities and municipalities lack the tools and locally relevant data to make effective policy decisions. This research aims to develop a practical framework for analyzing and comparing the carbon impact of policies enacted by municipal governments, and is specifically focused on the energy consumption, and operating and embodied carbon related to single-family dwellings (SFDs) in the City of Victoria, which contains a heterogeneous building stock with construction dates ranging between 1860 to present day. The underlying model has been developed based on statistical modeling and agent-based behavioral responses to different policy actions. The agent-based modelling approach models stock development in terms of new construction, retrofit, and replacement by simulating individual decisions at the building level. The results can be used to identify optimal efforts to minimizing barriers or bottlenecks in achieving low-carbon ambitions while understanding or addressing related aspects such as housing affordability. Municipalities can use the dashboard to identify and prioritize climate solutions that meet their stringent obligations.
Temperature flexible operation of district heating with booster heat pumps – Improving efficiency of existing networks
Authors: Adldinger S , Behringer L , Licklederer T , Zinsmeister D , Hamacher T 
Published: December 2023

Abstract
This paper illustrates a new approach for decarbonizing existing district heating networks by introducing Temperature Flexible District Heating Networks (TFDHs) using decentralized booster heat pumps. A rule-based control concept is presented to effectively manage the varying temperatures within the network. Based on an annual simulation, the optimal heat supply for TFDHs is determined and compared with simulated data of 3rd and 5th Generation district heating networks using the Levelized Costs Of Heat (LCOH) as a key performance indicator. The results of the calculations reveal a high decarbonization potential in transforming existing heat networks into temperature flexible heat networks, depending on the fuel source. TFDHs get economical, if the investment costs of the decentralized generation technology are reduced by 10 % and the natural gas price increases by 1 €ct/kWh.
Assessment of summer outdoor thermal comfort in an urban neighborhood with high-rise buildings
Authors: Kubilay A , Strebel D , Rubin A , Derome D , Carmeliet J 
Published: December 2023

Abstract
The use of urban vegetation and ventilation corridors can be beneficial in terms of outdoor thermal comfort. High-rise buildings modify urban ventilation by redirecting incident wind flow, which can further complicate local thermal conditions. The present study investigates the interaction of building morphology and urban vegetation during heat wave conditions. A coupled multiscale approach is performed that allows for a detailed analysis of the local impact of vegetation and high-rise buildings in an urban neighborhood in Zurich, Switzerland. Existing configuration in the neighborhood with low-rise buildings of mostly uniform height is modified with high-rise buildings. Mesoscale meteorological simulations are employed to drive the flow in building-resolved computational fluid dynamics (CFD) simulations at microscale. The results show significantly lower air temperature around groups of trees and along main streets aligned with the predominant wind direction. However, there are also locations where air temperature increases due to the presence of trees, especially when there is limited exchange with the main ventilation corridor. Initial simulations with high-rise buildings show that they can have a large influence on air temperature in the immediate neighborhood.
Influence of specific characteristics of subjects and environmental conditions on comfort level during showering
Authors: Albrecht K , Keuler J , Pärisch P 
Published: December 2023

Abstract
In systems that do not store domestic hot water (DHW), temperature fluctuations occur in the hot water temperature at the outlet when the DHW load changes. If these temperature fluctuations arrive at the tapping point, they influence the users’ perception of comfort. Especially in the shower these temperature fluctuations can lead to a loss of comfort. Unlike in the field of air conditioning, there have been relatively few studies on the perception of comfort in the shower, and these used only males as test subjects. Therefore, we started a study with 120 persons with the aim to involve a representative variety of test subjects. In our test facility a temperature profile with varying rates of change was imprinted and the test subjects provided feedback on whether they noticed temperature changes or found them uncomfortable. In this study, results on the comfort perception of the participants in the shower are examined in relation to individual factors such as gender, age or Body-Mass-Index (BMI), and the outside temperature. We cannot determine a specific impact of these factors on the comfort perception of a group of test subjects. Neither was an influence on the desired temperatures, which ranged between 33 °C and 45 °C, detected.
Impact of shade on outdoor thermal comfort, in the case of a Mediterranean Promenade
Authors: Tola A , Veleshnja J , Meunier P L , Bisha G 
Published: December 2023

Abstract
Outdoor thermal comfort is a frequent research topic nowadays. This research focuses on the Mediterranean coastal promenade, taking as a case study the coastal promenade of the city of Durres in Albania. The purpose of this research is to find out how and to what extent natural and artificial shades impact outdoor thermal comfort at the pedestrian’s level by including climate parameters during the analysis. The study is both quantitative and qualitative. Following an evaluation of the urban texture, thermal cameras and climatic instruments are used to conduct field measurements. Then, ENVI-met computer simulations are run with a focus on the PET index. The results of measurements and simulations of the promenade have indicated a high level of thermal stress. In the end, using computer simulation, two hypothetical scenarios are developed, taking into consideration the parameter of shade. They are set under identical climate circumstances on a common summer day. The results of the scenarios have shown that selecting the appropriate types of greenery and artificial shading improves pedestrian thermal comfort by 12-45 percent. Thus, it is very important how promenades and public spaces are designed, paying special attention to their physical elements such as natural and artificial shading.
Thermographic cameras for thermal comfort applications: simulated and experimental spectral response errors of various long-wave infrared detectors
Authors: Merchant C , Meggers F 
Published: December 2023

Abstract
Modern remote temperature sensing in the form of infrared imaging has become a widely used and important technique, with the ability to measure and characterize important but unseen Radiant heat. As more Long-wave Infrared (LWIR) detectors come to market aiming to meet a wide array of needs and goals, there is a need to differentiate and appraise LWIR detectors based upon the specific needs of thermal comfort research. While most detectors measure in the range of 8-14 μm, only 37.6% of the emitted energy of a blackbody at 300 K is contained in this spectral range. Thus, inherent to the operation of nearly all infrared detectors and cameras is an assumption about the emission curves of the objects sensed. Many materials in the built environment deviate significantly from the blackbody assumption, and the error due to this deviation is one which generic gray-body emissivity corrections are unable to fix — it is akin to taking black-and-white images with only the red channel of a camera, and using exposure compensation to correct the image to attempt a true monochrome rendition: there is simply missing information and the adjusted image will still be very clearly wrong. In this paper, we aim to evaluate by simulation and experiment the potential errors in infrared thermography used to drive thermal comfort heat transfer calculations due to intrinsic spectral assumptions of LWIR detectors.
Influence of the mass of energetic material and stand-off distance on the performance of perforator charges
Authors: Abd Elhady A , Riad A M , Shaker M A , Elshenawy T A 
Published: December 2023

Abstract
In this paper, the influence of the mass of Energetic Material (EM) and the relevant stand-off distance on the perforator charge performance has been investigated experimentally and numerically. An experimental program has been conducted, in which perforator charges have been constructed using different masses of an EM; where the relevant stand-off distances for the perforator charges have been changed accordingly. The constructed perforator charges with 33 mm in diameters are statically exploded against 1006 steel target and the depth of jet penetration for each tested perforator charge has been measured. Moreover, Autodyn-2D hydrocode is fed with the data of the constructed perforator charges to simulate their jet formation and its penetration process into 1006 steel target. The hydrocode predicts the dependence of the resultant jet velocity and its penetration depth into 1006 steel target on the mass of EM and the relevant stand-off distance. This dependence has also been confirmed by the corresponding static test results of small diameters perforator charges. Results show that the measured penetration depth increases from 11.0 to 13.7cm into 1006 steel target when the mass of EM increases from 36 to 41g and the relevant standoff distance decreases from 25.6 to 22.6 mm then; the penetration depth decreases again due to the limited standoff distance maintained for the tested perforator charges.
CFD simulation with analytical verification of discharging of nitrogen and helium from a high-pressure gas vessel
Authors: Elgezzar M , Rashad A , Hassan M S , Elnady T 
Published: December 2023

AbstractMany applications and industrial processes may necessitate the storage of large amounts of gases at high pressures. These compressed gases could be extremely dangerous if unintentionally released. since they could be poisonous or combustible when mixed with air. This research seeks to create a CFD model and undertake an analytical investigation of the process of de-pressurization of high-pressure gas from a vessel. The vessel to be studied is used in a pneumatic power system used to operate the control surface of a flying vehicle. The study involved two working fluids (nitrogen and helium). The discharging process is considered as a typical mass and heat transfer problem solved analytically by adopting The First Law of Thermodynamics to an unsteady flow control volume and simulated by employing transient flow analysis to the CFD model. The research was carried out on 440 bars (absolute pressure) of pressurized gas vessels. Working gases for the study included nitrogen and helium. Analytical solution results for the two different gases have been compared with the CFD simulation results to assess the CFD model’s accuracy. A good match is achieved when the gas temperature, pressure, density, and outlet mass flow rate variations are compared. The results demonstrated a good match between the CFD and analytical data, proving the validity of the CFD model.
Experimental and numerical Investigation of entrapped air presence and expulsions in irregular pipelines on hydraulic transients
Authors: Warda H A , Wahba E M , Elamrousy S I 
Published: December 2023

Abstract
In the present study, the transient event of rapid opening of upstream valve in undulated water pipeline with entrapped air pockets was investigated both experimentally and numerically. Pressure peaks and oscillation patterns were traced with the variation of air pocket length, blocking column length and water filling column. A transient two-dimensional CFD simulation model was introduced and validated by laboratory experiments. The proposed CFD model was conducted using ANSYS fluent based on Reynolds-averaged Navier–Stokes (RANS) equations and the volume of fluid (VOF) method. A user-defined functions (UDF) for both water compressibility effect and opening valve estimated pattern were adopted to verify the experimental results. For further understanding of transient response air expulsion through air vents of various orifices diameters were experimentally investigated. Image processing technique by using photoshop were utilized to clarify Stages of air expulsions, air water interaction and orifice flow regime. The obtained results showed that pressure peaks and oscillations depend strongly on orifice size where small orifice caused an intermitted flow choked by water column in contrast to large orifice where water hammer was dominated. An experimental facility was constructed at Alexandria university hydraulics laboratory to fulfil the research objectives. Air presence challenges in hydraulic systems are extensively applied for water and fuel supply lines, firefighting, and drainage systems in airports ground facilities.
Effect of salinity on marine propeller performance
Authors: Ghoniem A M , Abo Elazm A S , Benaya M I , Mohamed S A 
Published: December 2023

Abstract
In order to analyse problems with fluid flow, computational fluid dynamics is one of the most helpful tools available. This paper presents a numerical simulation of the effect of salinity on a marine propeller of an aircraft carrier in advance of the propeller open water (POW) test. A five-bladed fixed-pitch propeller is analysed using an unstructured mesh in the flow domain (PPTC - VP1304). Solving the RANSE equations describing the flow with a streamlined solver To begin, the accuracy of the numerical model was checked by comparing the results to previously published experimental data on the propeller. The verified model was then used to investigate how salinity impacted propeller performance in open water. The effect of fluctuating salinity was investigated by adjusting the properties of the flow fluid in a computational model. Lower advance ratios are where the effect of salinity, a decrease in efficiency of up to 4%, really shows up. However, it had little to no effect at higher advance ratios.
A novel in-flight thrust modulation technique for SPRM: proof of concept
Authors: Abdelraouf A M , Mahmoud O K , Al-Sanabawy M A 
Published: December 2023

Abstract
Thrust modulation (termination or reduction) is one of the most sophisticated topics in rocket motors. Thrust termination is employed when combustion must be terminated to ensure proper stage separation, to avoid motor explosion, to attain certain range, or for research purposes. While liquid and hybrid propellant rocket motors have the ability to extinguish thrust, thrust termination in solid propellant rocket motors (SPRMs) need the use of specialized technology. In-flight thrust termination of (SPRMs) can be achieved by sudden and sufficient increase in throat area. Increasing throat area causes high depressurization rate which consequently leads to extinguishing the rocket motor. In contrast, in-flight thrust reduction can be theoretically attained either by reducing chamber pressure to a new equilibrium level or by reducing the divergent section length. The objective of the present paper is to prove the concept of using Linear Shaped Charge (LSC) for thrust modulation; a technique novel to SPRM applications. Thrust termination concept is proved via a set of static firing tests on a standard test motor. In addition, a mathematical model is developed to predict the drop in thrust due to cutting the nozzle at any arbitrary location. The model is validated by comparing with published experiments for thrust termination and reduction. A parametric study is conducted based on model results. It is confirmed that by cutting the nozzle along its divergent section, thrust reduction less than 20% can be attained. Further reduction can be achieved by cutting the nozzle along its convergent section.
Enhanced range-doppler algorithm for SAR image formation
Authors: Sakr M , Amein A S , Ahmed F M , Amer G M , Youssef A 
Published: December 2023

Abstract
A Synthetic Aperture Radar (SAR) system is a powerful source of information due to its capability to operate day and night and in all weather conditions. It is essential for military and civilian purposes. Pulse-focusing is employed by the SAR system for achieving both long-range detection and fine-range resolution. The Range-Doppler Algorithm (RDA) is the most popular pulse-focusing technique for creating images from coherent SAR data. Pulse compression techniques for SAR signal processing targets seek to improve map resolution, lower peak power, and increase the Signal-to-Noise Ratio (SNR) of the detected object. This paper demonstrates an enhanced RDA algorithm that uses a modified pulse compression technique based on mismatched filter optimization where Quadratic Constrained Quadratic Program (QCQP) is used. The performance evaluation of the proposed method is performed using visual assessment and the standard image quality metrics peak-side-lobe-ratio (PSLR), impulse-response-width (IRW), and integrated-side-lobe-ratio (ISLR). Simulated and real SAR raw data are used for performance evaluation. The experimental results demonstrate the proposed method’s robustness, efficiency, and reliability in providing a higher-quality SAR image than the traditional RDA algorithm.
Effective reduction of sidelobes in pulse compression radars using NLFM signal processing approaches
Authors: Selim M G , Mabrouk G G , Elsherif A K , Youssef A 
Published: December 2023

Abstract
Pulse compression techniques are widely used in modern radar systems to enhance range resolution and detection capability. As signal design is one of the basic factors of an efficient radar system, the problem of designing a radar signal with good characteristics using pulse compression is addressed in this paper. A linear frequency modulated (LFM) waveform has been widely used for conventional radars. However, it has a higher sidelobe level which makes the detection of weak targets very difficult in presence of strong targets returns and as a result the problem of masking occurs. In order to get suppressed sidelobes of radar matched filter output as well as preserve the main lobe resolution and level to overcome the problem of masking, nonlinear frequency modulated (NLFM) signals are used in modern radars. In this paper, we will introduce two different approaches to design an optimized NLFM signal which is characterized by optimized sidelobe level (SLL). The first is the exponential piecewise linear function (EPWL) which is the modification of piecewise linear (PWL) functions relying on an exponential predistortioning function. The second is the odd-term polynomial approximation (OTPA) in which the generation of NLFM signal depends only on odd-powered terms of the polynomial function. Furthermore, the simulation results of autocorrelation functions (ACF) of the proposed signals show its superiority over the traditional LFM signals and significantly enhancement compared to the recent background work. The Doppler sensitivity of the designed signals has been evaluated, revealing that the first approach offers Doppler tolerance and is suitable for surveillance radar systems, while the second approach with a lower sidelobe level is used in applications such as Synthetic Aperture Radar (SAR). Finally, the ambiguity function of the designed signals has been measured to illustrate the effect of the Doppler effect relative to different velocities.