![]() Shirani, Arsalan ![]() ![]() in Fluid Dynamics & Material Processing (in press) The application of air-based heating systems as a possible approach to reduce the construction costs in highly efficient residential buildings is becoming popular. Air-based heating systems have been well ... [more ▼] The application of air-based heating systems as a possible approach to reduce the construction costs in highly efficient residential buildings is becoming popular. Air-based heating systems have been well-known for their usage in passive houses during the past three decades. Available studies on such systems tend mostly to focus only on comparing exhaust air heat pump technology with conventional systems in efficient buildings. Moreover, most of the existing studies ignore the usual presence of the electrical heaters as backup. Besides, a comprehensive study and comparison between different air-based heating system concepts is still missing. In this study, four different air-based heating system concepts separated by the type of heat source of heat pump for heating and domestic hot water are defined. These systems are compared to four conventional heating system, including floor heating and direct electrical system employing dynamic annual simulations. According to simulation results, the systems with floor heating have shown the best system efficiencies and the lowest energy demand in comparison to the other systems. The main reason for this was the lower supply temperatures of the floor heating systems. Between the air heating systems, the system equipped with an outdoor air heat pump showed a better energy performance than an exhaust air system. The main reason for this could be attributed to the power limitation of exhaust air heat pump systems. [less ▲] Detailed reference viewed: 99 (10 UL)![]() Soliman, Ahmed Abdelsalam Mohamed ![]() ![]() in Medical Engineering and Physics (2024), 119 Anterior pelvic ring fractures are common in geriatric patients. The Supraacetabular External Fixator (SEF) is a relatively simple and effective surgical procedure. On the other hand, there is the option ... [more ▼] Anterior pelvic ring fractures are common in geriatric patients. The Supraacetabular External Fixator (SEF) is a relatively simple and effective surgical procedure. On the other hand, there is the option of a Subcutaneous Iliopubic Plate (SIP) osteosynthesis. Only limited comparative biomechanical data of these two devices are available. Therefore, this biomechanical study’s objective was to compare the stabilizing effect of the SEF versus the SIP in a model of Fragility Fractures of the Pelvis (FFP) type Ia. A test stand for pelvic biomechanics testing that emulates the gait loading cycle with physiological relevance was used. The osteotomy on the right pelvic ring was stabilized either with the SEF or the SIP. Strain gauges were used to measure strain in the pelvic ring. The osteotomy’s spatial interfragmentary displacement (SID) was monitored using a 3D digital image correlation system. The SEF stabilization reduced the SID by approximately 10%, whereas the locking SIP could reduce displacement by about 62%. Additionally, the SIP reduced the stress/strain levels by 67% in the posterior pelvic ring. We could demonstrate that the SIP is superior to SEF in treating FFP type Ia as it significantly reduced the osteotomy’s SID and the strain in the posterior pelvic ring. [less ▲] Detailed reference viewed: 44 (2 UL)![]() Soliman, Ahmed Abdelsalam Mohamed ![]() ![]() in Journal of Biomechanical Engineering (2023) Biomechanical testbench emulating the physiological loading of the pelvis is crucial in developing reconstructive implants for fragility fractures of the pelvis. Additionally, it will help understand the ... [more ▼] Biomechanical testbench emulating the physiological loading of the pelvis is crucial in developing reconstructive implants for fragility fractures of the pelvis. Additionally, it will help understand the influence of the common daily loading on the pelvic ring. However, most reported experimental studies were mainly comparative with simplified loading and boundary conditions. In (Part I - Computational Design of Experiments) of our study, we described the concept of the computational experiment design to design and construct a biomechanical testbench emulating the gait movement of the pelvis. The 57 muscles and joints' contact forces were reduced to four force actuators and one support, producing a similar stress distribution. The experimental setup is explained in this paper (Part II - Experimental Testing), and some experimental results are presented. In addition, a series of repeatability and reproducibility tests were conducted to assess the test stand capabilities of replicating the gait physiological loading. The calculated stresses and the experimentally recorded strains showed that the pelvic ring response to the loading always follows the loaded leg side during the gait cycle. Furthermore, the experimental results of the pelvis displacement and strain at selected locations match the numerical ones. The developed test stand and the concept of computational experiment design behind it provide guidelines on how to design biomechanical testing equipment with physiological relevance. [less ▲] Detailed reference viewed: 47 (2 UL)![]() Soliman, Ahmed Abdelsalam Mohamed ![]() ![]() in Journal of Biomechanical Engineering (2023) Biomechanics of the human pelvis and the associated implants are still a medical and engineering debated topic. Today, no biomechanical testing setup is dedicated to pelvis testing and associated ... [more ▼] Biomechanics of the human pelvis and the associated implants are still a medical and engineering debated topic. Today, no biomechanical testing setup is dedicated to pelvis testing and associated reconstructive implants with accepted clinical relevance. This paper uses the Computational Experiment Design procedure to numerically design a biomechanical test stand that emulates the pelvis physiological gait loading. The numerically designed test stand reduces the 57 muscles and joints' contact forces iteratively to only four force actuators. Two hip joints' contact forces and two equivalent muscle forces with a maximum magnitude of 2.3 KN are applied in a bilateral reciprocating action. The stress distribution of the numerical model of the developed test stand is very similar to that of the numerical model of the pelvis with all 57 muscles and joint forces. For instance, at the right arcuate line, the state of stress is identical. However, at the location of superior rami, there is a deviation ranging from 2% to 20% between the two models. The boundary conditions and the nature of loading adopted in this study are more realistic regarding the clinical relevance than state-of-the-art. The numerically developed biomechanical testing setup of the pelvis in this numerical study (part I - Computational Design of Experiments) was found to be valid for the experimental testing of the pelvis. The construct of the testing setup and the experimental testing of an intact pelvis under gait loading is discussed in detail in part II - Experimental Testing. [less ▲] Detailed reference viewed: 38 (2 UL)![]() Dakhili, Khatereh ![]() ![]() ![]() in Life-Cycle of Structures and Infrastructure Systems (2023) The performance of bridge damage assessment based on model updating ap-proaches relies on correctly identifying the structural responses in the undamaged state. However, environmental uncertainties, such ... [more ▼] The performance of bridge damage assessment based on model updating ap-proaches relies on correctly identifying the structural responses in the undamaged state. However, environmental uncertainties, such as temperature changes, influence structural responses in the same order of magnitude as damages. Therefore, a prestressed concrete bridge beam is studied in this paper. Temperature influences on static experiments in 2 test periods are minimized with physical temperature compensation technique. Displacement fluctuations decrease at least 60% after temperature compensation, making the summer and winter measurements comparable. Next, temperature-compensated Influence Lines (ILs), static flexibility and stiffness matrices are ob-tained. Comparing the results reveal the importance of performing measurements only on cloudy days. This paper contributes to differentiating between temperature effects and damages, which is crucial for a successful damage assessment. [less ▲] Detailed reference viewed: 35 (0 UL)![]() ; Soliman, Ahmed Abdelsalam Mohamed ![]() in Trauma Case Reports (2022), 42 Introduction: Anterior pelvic ring fractures are common in geriatric patients. Current treatment algorithms recommend osteosynthesis if no pain free mobilisation is possible. For this a multitude of ... [more ▼] Introduction: Anterior pelvic ring fractures are common in geriatric patients. Current treatment algorithms recommend osteosynthesis if no pain free mobilisation is possible. For this a multitude of surgical techniques have been described. Among these the Supraacetabular External Fixator (SEF) is regarded a simple and effective surgical procedure. However, this technique is associated with significant drawbacks. Alternatively, there is the option of an internal fixator or a formal plate osteosynthesis. It is the objective of this case report to present the Subcutaneous Iliopubic Plate (SIP) in a fragility fracture of the anterior and posterior pelvic ring. Case report: An 83-year-old female patient sustained a fracture of the anterior pelvic ring, the lateral sacrum and the medial femoral neck. After initially refusing any surgery, the patient agreed to have the endoprosthesis implanted first, and then secondarily to dorsoventral osteosynthesis of the pelvis. Dorsally a transiliosacral screw osteosynthesis was performed. Anteriorly a bilateral subcutaneous iliopubic plate-osteosynthesis was chosen, a plate position that is anterior to the aponeurosis. Conclusions: The subcutaneous plate has proven to be a quick and uncomplicated surgical procedure that is significantly better tolerated by patients than external stabilization. [less ▲] Detailed reference viewed: 42 (8 UL)![]() Soliman, Ahmed Abdelsalam Mohamed ![]() ![]() Scientific Conference (2022, October 28) Detailed reference viewed: 106 (13 UL)![]() Soliman, Ahmed Abdelsalam Mohamed ![]() ![]() Scientific Conference (2022, October 28) Detailed reference viewed: 73 (10 UL)![]() ; Soliman, Ahmed Abdelsalam Mohamed ![]() Poster (2022, October 26) Detailed reference viewed: 51 (15 UL)![]() ; Dakhili, Khatereh ![]() in Journal of Civil Structural Health Monitoring (2022) Bridges are among the most important components of transportation systems. Timely damage detection of these structures not only ensures reliability but also prevents catastrophic failures. This paper ... [more ▼] Bridges are among the most important components of transportation systems. Timely damage detection of these structures not only ensures reliability but also prevents catastrophic failures. This paper addresses the damage assessment of bridges based on model updating techniques. Artificial damage was introduced to a beam that was a part of a real prestressed concrete bridge. The magnitude of the damage was increased stepwise, and static loading experiments were conducted in each step. A linear Finite-Element (FE) model with solid elements that were clustered into slices was utilised. A Gaussian bell-shaped curve was used as a damage function to describe the crack location using only three parameters. The experiments focused on sagging under dead load. Damage identification was performed in two steps using a coarse and a refined model. Initially, the FE model with a coarse mesh was updated to approximately localise the damage. Then, the FE model is refined in the vicinity of the approximately localised damage, and damage identification was accurately achieved. The results show that after the second step, the maximum error value of damage localisation is less than 0.5%. This approach could be later used to detect small damages that are not visible. [less ▲] Detailed reference viewed: 40 (10 UL)![]() Soliman, Ahmed Abdelsalam Mohamed ![]() ![]() Scientific Conference (2022, June 27) Detailed reference viewed: 38 (13 UL)![]() ; ; et al in CLIMA 2022 conference (2022, May) Schools are learning communities where multiple stakeholders can collaborate to learn about energy efficiency, including via formal curricula, non-formal learning and day-to-day practices. Furthermore, by ... [more ▼] Schools are learning communities where multiple stakeholders can collaborate to learn about energy efficiency, including via formal curricula, non-formal learning and day-to-day practices. Furthermore, by improving energy literacy among building occupants, the energy efficiency of schools can be improved. However, turning schools into learning communities rather than learning organizations is still problematic. This article details a case study realised in the form of the ENERGE project, which integrates technological, educational and practical activities in 13 post-primary schools from 6 European countries. Owing to an extensive collaboration of diverse stakeholders, the ENERGE project resulted in the origination of a learning community around energy efficiency in the schools. The outcomes of building a learning community within the ENERGE project included: capacity building (in the form of the ENERGE Committees and Teacher Network), the introduction of digital education (via the ENERGE digital platform), development of curriculum-based modules to raise energy literacy, and the establishment of a viable model for expanding ENERGE experience to other schools. The article concludes by explaining the benefits of the ENERGE approach for stakeholders. [less ▲] Detailed reference viewed: 50 (8 UL)![]() Dakhili, Khatereh ![]() ![]() in VDI-Berichte 2379, 7. VDI-Fachtagung Baudynamik 27. und 28. April 2022, Würzburg (2022, April) An increasing number of bridges are approaching the end of their service life due to corrosion and fatigue. Damages can be detected by performing regular measurements of characteristic values and ... [more ▼] An increasing number of bridges are approaching the end of their service life due to corrosion and fatigue. Damages can be detected by performing regular measurements of characteristic values and comparing them with reference state data when there is no damage in the bridge. Unfortunately, environmental factors such as temperature variations have a considerable impact on the measurements and structural properties, such as stiffness. Since these environmental effects can be in the same order as damage, it is important to quantify them and reduce their effect before damage assessment. This paper aims to establish a correct reference model by investigating the parameters that affect structural responses. Doing so enables discrimination between structural property changes caused by damage and parameters such as temperature variations, load uncertainties, and various bearings. In this regard, several static and dynamic experiments are performed on a full scale undamaged prestressed concrete beam from a demolished bridge, and the results are reported. [less ▲] Detailed reference viewed: 141 (18 UL)![]() Latz, Sebastian ![]() ![]() in Konferenzbeiträge Bauphysiktage Kaiserslautern 2022 (2022), 5 Der fortschreitende Klimawandel verlangt ein Umschwenken, weg von der fossilen Energieversorgung und hin zu den Erneuerbaren, wobei nachhaltige Tourismusangebote auch verstärkt einbezogen werden müssen ... [more ▼] Der fortschreitende Klimawandel verlangt ein Umschwenken, weg von der fossilen Energieversorgung und hin zu den Erneuerbaren, wobei nachhaltige Tourismusangebote auch verstärkt einbezogen werden müssen. Der Campingplatz Treviris liegt auf dem Gelände des Rudervereins Treviris Trier und verzeichnet jährlich von Mitte April bis Mitte Oktober zwischen 40 und 50.000 Übernachtungen. Im Zuge des Neubaus des Bootshauses wird der vorhandene Gasanschluss zurückgebaut und die gesamte Wärme- und Stromversorgung der Liegenschaft muss auf regenerative Energien umgestellt werden. So soll der Bedarf des Campingplatzes, des Bootshauses (KfW 40 EE), der angegliederten Wohnbebauung mit zehn Wohneinheiten (KfW 40+) sowie mehrere Ladestationen emissionsneutral durch Sonnenenergie versorgt werden. Hauptbestandteile des Konzeptes sind eine 105 kWpeak PV Anlage mit 90 kWh Batteriespeicher sowie zwei Wärmepumpen, die um eine 80 m² hybride solarthermische Photovoltaikanlage (PVT) auf dem Campingplatz ergänzt werden soll. Insbesondere die Warmwasserversorgung des Campingplatzes ist hierbei eine Herausforderung, da die auftretenden Leistungsspitzen von 4m3 Warmwasser (WW) in 2 h nicht ausschließlich mittels Wärmepumpe bereitgestellt werden können. Es wird auf Wärmespeicher mit zentraler Frischwasserstation zurückgegriffen. Für die Dimensionierung der Hauptkomponenten: PVT Feld, Wärmepumpe und Pufferspeicher wird eine Zeitreihenanalyse mit variierendem Bedarf und schwankendem Solarangebot durchgeführt. [less ▲] Detailed reference viewed: 87 (0 UL)![]() Latz, Sebastian ![]() ![]() ![]() in Bauphysik (2022), 1 Following the European directive to reduce CO2 emissions of existing buildings by improving energy efficiency, internal insulation systems play a central role in the renovation of historically valuable ... [more ▼] Following the European directive to reduce CO2 emissions of existing buildings by improving energy efficiency, internal insulation systems play a central role in the renovation of historically valuable buildings which cannot be insulated from the outside for reasons of monumental protection, or in cases where no additional exterior space is available. However, besides the thermal property of insulation systems, there are other relevant properties to be considered before choosing an internal insulation system, such as the hygrothermal behavior which plays a particularly important role in diffusion-open interior insulation systems. As the internal insulation layer reduces the temperature of the existing wall during the heating season, its drying potential after rain events is considerably reduced. In addition to the effects of moisture from the outside (mainly wind driven rain), the entry of humidity from the inside through diffusion plays an important role. In the presented study, high performance insulation materials with nanostructure based on silicon dioxide and polyurethane are compared to conventional material based on wood fiber from a hygrothermal point of view by analyzing in situ measurements and simulations. [less ▲] Detailed reference viewed: 61 (5 UL)![]() Dakhili, Khatereh ![]() ![]() in Bridge Safety, Maintenance, Management, Life-Cycle, Resilience and Sustainability (2022) Being an indispensable part of transportation systems, Structural Health Monitoring (SHM) of bridges has been increasingly studied. Various SHM techniques not only enhance reliability and safety but also ... [more ▼] Being an indispensable part of transportation systems, Structural Health Monitoring (SHM) of bridges has been increasingly studied. Various SHM techniques not only enhance reliability and safety but also reduce maintenance costs. Various bridge deteriorations change the structural properties, such as flexibility and stiffness. Therefore, damage assessment can be achieved by monitoring the structural matrices of bridges and tracking the deviations from the healthy-state or reference data. This paper focuses on damage detection of a prestressed concrete beam from a demolished bridge based on the flexibility matrix. The dynamic and static flexibility matrices are calculated numerically and experimentally when the beam is undamaged. The simulated and measured static flexibility matrices differ by only about 5 %. Additionally, the numerical dynamic flexibility matrix is strongly correlated with static results. The findings of this study can be employed as a basis for future damage detection applications when artificial damage is introduced. [less ▲] Detailed reference viewed: 81 (11 UL)![]() Repplinger, Christian ![]() ![]() ![]() in Fatigue and Fracture of Engineering Materials and Structures (2021) Stress relaxation describes the reduction of stress under static or cyclic loading at a constant strain level. Several processes induce intentionally residual stresses, for example, autofrettage of thick ... [more ▼] Stress relaxation describes the reduction of stress under static or cyclic loading at a constant strain level. Several processes induce intentionally residual stresses, for example, autofrettage of thick-walled pressurized tubes to improve their fatigue life. This well-known process induces residual compressive stresses at the critical inner surface by using a single static but controlled over- loading internal pressure. Relaxation of residual stresses due to cyclic loading in service would endanger the effectiveness of autofrettage and could finally lead to unexpected fatigue failure. In this study, strain-controlled experiments up to 500,000 load cycles and amending nonlinear finite element simulations were done for the aluminum alloys EN AW 6061 T6 and EN AW 6082 T6 to study potential cyclic stress relaxation in four-point bending tests after con- trolled single static plasticization for residual stress generation. This analysis identifies almost stable residual stresses for both materials under different cyclic strain-controlled load levels. [less ▲] Detailed reference viewed: 70 (7 UL)![]() Repplinger, Christian ![]() ![]() ![]() in Repplinger, Christian (Ed.) 47. VDI-Jahrestagung: Schadensanalyse 2021 - Wasserstoff in metallischen Bauteilen und Mediale und klimatische Beanspruchung von polymeren Produkten (2021, October) Detailed reference viewed: 71 (10 UL)![]() Soliman, Ahmed Abdelsalam Mohamed ![]() ![]() Poster (2021, September) This study investigates the influence of personalizing musculoskeletal models (MS) on muscles, contact joints forces and on stresses in the pelvic ring bones during normal gait loading cycle. All ... [more ▼] This study investigates the influence of personalizing musculoskeletal models (MS) on muscles, contact joints forces and on stresses in the pelvic ring bones during normal gait loading cycle. All calculated forces are utilized to predict stress states in pelvis bones using Finite Element (FE) software. Customized MS models provides more precise muscle and contact forces. Additionally, it enables more automatic coupling between MS and FE environments by data transfer. [less ▲] Detailed reference viewed: 75 (15 UL)![]() Kebig, Tanja ![]() ![]() ![]() Conference given outside the academic context (2021) A rising number of concrete bridges are showing increasing damage due to corrosion and fatigue. In addition to the regular standard visual inspection, the bridge’s condition can also be recorded using ... [more ▼] A rising number of concrete bridges are showing increasing damage due to corrosion and fatigue. In addition to the regular standard visual inspection, the bridge’s condition can also be recorded using additional tests with repeated static loading and/or dynamic tests. To determine any damage to a structure and to check its structural stability, it is crucial to know the exact system properties of the bridge in its undamaged reference state. The system behavior is influenced by damage and bearing conditions and environmental influences, such as the structure’s temperature. The influence of temperature can even cause larger changes in the measured quantities (bending line or modal parameters) than real damage. Therefore, temperature effects should be compensated before any condition analysis. The present work aims to demonstrate the influence of different bearing types and temperature on a real bridge beam. For this purpose, various static and dynamic tests were performed in the undamaged reference state. [less ▲] Detailed reference viewed: 161 (32 UL) |
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