Pub Date : 2026-01-01Epub Date: 2026-08-25DOI: 10.1186/s44147-026-01183-4
Nikolaos D Tantaroudas, Ilias Karachalios
<p><p>This paper quantifies, in a systematic parametric fashion, the manner in which geometric nonlinearity and structural flexibility alter the flight dynamic characteristics of high-aspect-ratio wings representative of high-altitude long-endurance (HALE) aircraft. A coupled aeroelastic-flight dynamic model is assembled from established constituent formulations-a geometrically-exact beam representation of the structural dynamics, unsteady two-dimensional strip theory for the aerodynamic loading, and quaternion-based rigid-body equations for the flight mechanics-into a monolithic system in which consistent load and motion transfer is enforced at every integration time step. The contribution lies not in new modelling methodology but in the systematic single-parameter investigation this framework enables: the wing stiffness is varied continuously across four orders of magnitude through a non-dimensional flexibility parameter, spanning from effectively rigid to highly flexible configurations, with planform, mass distribution, and flight condition held fixed. The study reveals that increasing flexibility profoundly modifies the trim conditions, flutter boundaries, and the dynamic gust response. In particular, over the flexibility range in which the trimmed state is physically valid, the trim angle of attack is found to vary non-monotonically with flexibility: torsional wash-in initially lowers the required trim angle, whereas increasing static deformation produces an effective dihedral that reorients the local lift vectors and, as the wing bends further, demands higher trim angles to maintain vertical force equilibrium. The degradation of flutter speed with increasing flexibility is quantified through an aeroelastic mode-tracking analysis and is shown to depend on whether the pre-stressed equilibrium state is incorporated, with the pre-stress correction reaching about three per cent at the upper end of the physically valid flexibility range. Consistent with previously published findings, flexibility is found to erode longitudinal flight-dynamic (phugoid) stability so that active control becomes essential; the present framework, constructed and validated for the aeroelastic response, treats this trend qualitatively and does not claim quantitative flight-dynamic eigenvalues, which require a dedicated flight-mechanics model. The framework is validated against established HALE aircraft benchmark cases, demonstrating close agreement in structural natural frequencies, flutter and divergence speeds, and rigid-aircraft trim; the static aeroelastic deflections are conservative (overpredicted) with respect to three-dimensional aerodynamic references, a documented consequence of the two-dimensional strip aerodynamics that is discussed openly in the paper. The results provide quantitative criteria for identifying the conditions under which linear analysis remains adequate and the circumstances under which fully coupled nonlinear computational tools become indisp
{"title":"Nonlinear flexibility effects on flight dynamics of high-aspect-ratio wings.","authors":"Nikolaos D Tantaroudas, Ilias Karachalios","doi":"10.1186/s44147-026-01183-4","DOIUrl":"https://doi.org/10.1186/s44147-026-01183-4","url":null,"abstract":"<p><p>This paper quantifies, in a systematic parametric fashion, the manner in which geometric nonlinearity and structural flexibility alter the flight dynamic characteristics of high-aspect-ratio wings representative of high-altitude long-endurance (HALE) aircraft. A coupled aeroelastic-flight dynamic model is assembled from established constituent formulations-a geometrically-exact beam representation of the structural dynamics, unsteady two-dimensional strip theory for the aerodynamic loading, and quaternion-based rigid-body equations for the flight mechanics-into a monolithic system in which consistent load and motion transfer is enforced at every integration time step. The contribution lies not in new modelling methodology but in the systematic single-parameter investigation this framework enables: the wing stiffness is varied continuously across four orders of magnitude through a non-dimensional flexibility parameter, spanning from effectively rigid to highly flexible configurations, with planform, mass distribution, and flight condition held fixed. The study reveals that increasing flexibility profoundly modifies the trim conditions, flutter boundaries, and the dynamic gust response. In particular, over the flexibility range in which the trimmed state is physically valid, the trim angle of attack is found to vary non-monotonically with flexibility: torsional wash-in initially lowers the required trim angle, whereas increasing static deformation produces an effective dihedral that reorients the local lift vectors and, as the wing bends further, demands higher trim angles to maintain vertical force equilibrium. The degradation of flutter speed with increasing flexibility is quantified through an aeroelastic mode-tracking analysis and is shown to depend on whether the pre-stressed equilibrium state is incorporated, with the pre-stress correction reaching about three per cent at the upper end of the physically valid flexibility range. Consistent with previously published findings, flexibility is found to erode longitudinal flight-dynamic (phugoid) stability so that active control becomes essential; the present framework, constructed and validated for the aeroelastic response, treats this trend qualitatively and does not claim quantitative flight-dynamic eigenvalues, which require a dedicated flight-mechanics model. The framework is validated against established HALE aircraft benchmark cases, demonstrating close agreement in structural natural frequencies, flutter and divergence speeds, and rigid-aircraft trim; the static aeroelastic deflections are conservative (overpredicted) with respect to three-dimensional aerodynamic references, a documented consequence of the two-dimensional strip aerodynamics that is discussed openly in the paper. The results provide quantitative criteria for identifying the conditions under which linear analysis remains adequate and the circumstances under which fully coupled nonlinear computational tools become indisp","PeriodicalId":55892,"journal":{"name":"Journal of Engineering and Applied Science","volume":"73 1","pages":"332"},"PeriodicalIF":0.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13540659/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148889315","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01DOI: 10.21608/mjcu.2025.423594
Manal Amer
Background: Of all glial tumors, glioblastoma (GBM) is the most malignant. They represent around 54% of all gliomas and 16% of primary brain tumors. They have a very poor prog-nosis and extraordinarily high recurrence rates. The role of sur-gery after recurrence is still controversial to this day. Aim of Study: This study aims to clarify the importance of surgery in the management of recurrent GBM. Patients and Methods: This was a retrospective study done on 47 patients that were dichotomized into 2 groups. 27 patients were in the single resection group (SRG). 20 patients were in the multiple resection group (MRG). The patients were com-pared together through their overall survival (OS). Other pos-sible prognostic factors such as the extent of resection (EOR) and age were also analyzed. Results: Patients in the MRG experienced significantly better survival over those in the SRG (median OS 36 vs. 11 months respectively p=0.01). Other factors also affected the overall survival. Complications after the first surgery decreased survival in patients to a median OS of 9 months as opposed to patients who didn’t experience complications with a median OS of 24 months (p<0.001). Both pre and postoperative per-formance status affected the OS of patients (p<0.0001). EOR also had an impact on OS. Patients who were operated upon by subtotal resection had worse outcomes when compared with those operated upon by gross total resection (median OS 9 vs. 24 months respectively p=0.026). Conclusion: Surgery increases survival in recurrent GBM, as well as other factors such as age, performance status, EOR, and postoperative complication. Performance status, however, was found to be the main prognostic indicator of survival in these patients (p<0.001). Gender, tumor site, tumor extension, and clinical presentation do not appear to have any effect on survival.
{"title":"The Role of Surgery in Recurrent Glioblastoma Multiforme: A Retrospective Study","authors":"Manal Amer","doi":"10.21608/mjcu.2025.423594","DOIUrl":"https://doi.org/10.21608/mjcu.2025.423594","url":null,"abstract":"Background: Of all glial tumors, glioblastoma (GBM) is the most malignant. They represent around 54% of all gliomas and 16% of primary brain tumors. They have a very poor prog-nosis and extraordinarily high recurrence rates. The role of sur-gery after recurrence is still controversial to this day. Aim of Study: This study aims to clarify the importance of surgery in the management of recurrent GBM. Patients and Methods: This was a retrospective study done on 47 patients that were dichotomized into 2 groups. 27 patients were in the single resection group (SRG). 20 patients were in the multiple resection group (MRG). The patients were com-pared together through their overall survival (OS). Other pos-sible prognostic factors such as the extent of resection (EOR) and age were also analyzed. Results: Patients in the MRG experienced significantly better survival over those in the SRG (median OS 36 vs. 11 months respectively p=0.01). Other factors also affected the overall survival. Complications after the first surgery decreased survival in patients to a median OS of 9 months as opposed to patients who didn’t experience complications with a median OS of 24 months (p<0.001). Both pre and postoperative per-formance status affected the OS of patients (p<0.0001). EOR also had an impact on OS. Patients who were operated upon by subtotal resection had worse outcomes when compared with those operated upon by gross total resection (median OS 9 vs. 24 months respectively p=0.026). Conclusion: Surgery increases survival in recurrent GBM, as well as other factors such as age, performance status, EOR, and postoperative complication. Performance status, however, was found to be the main prognostic indicator of survival in these patients (p<0.001). Gender, tumor site, tumor extension, and clinical presentation do not appear to have any effect on survival.","PeriodicalId":55892,"journal":{"name":"Journal of Engineering and Applied Science","volume":"93 03","pages":"405-418"},"PeriodicalIF":0.0,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147912818","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-13DOI: 10.1186/s44147-024-00486-8
Ayman Hamdy Kassem, Muhammad Asem
{"title":"A low-cost robotic system for simultaneous localization and mapping","authors":"Ayman Hamdy Kassem, Muhammad Asem","doi":"10.1186/s44147-024-00486-8","DOIUrl":"https://doi.org/10.1186/s44147-024-00486-8","url":null,"abstract":"","PeriodicalId":55892,"journal":{"name":"Journal of Engineering and Applied Science","volume":"36 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141650843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Evaluation of surface response of SiC and fly ash-filled Prosopis juliflora fibre-reinforced epoxy composites under dry sliding wear conditions using Taguchi method","authors":"Suresh Thirupathi, Ayyappan Solai, Shenbaga Velu Pitchumani, V. Gopalan, Elango Mallichetty","doi":"10.1186/s44147-024-00485-9","DOIUrl":"https://doi.org/10.1186/s44147-024-00485-9","url":null,"abstract":"","PeriodicalId":55892,"journal":{"name":"Journal of Engineering and Applied Science","volume":"57 20","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141654727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-11DOI: 10.1186/s44147-024-00488-6
Amera S. Shehab El-Deen, Ahmed H. Aboulsaadat, Walaa Nour
{"title":"Reviving the past: urban strategies for renovating historic commercial streets in city centers","authors":"Amera S. Shehab El-Deen, Ahmed H. Aboulsaadat, Walaa Nour","doi":"10.1186/s44147-024-00488-6","DOIUrl":"https://doi.org/10.1186/s44147-024-00488-6","url":null,"abstract":"","PeriodicalId":55892,"journal":{"name":"Journal of Engineering and Applied Science","volume":"117 26","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141656800","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-11DOI: 10.1186/s44147-024-00484-w
Yiwen Hu, Chao Liang
{"title":"Study on the spatial relationship between road network and the diversity of urban public facilities: the case of the central area of Changsha City","authors":"Yiwen Hu, Chao Liang","doi":"10.1186/s44147-024-00484-w","DOIUrl":"https://doi.org/10.1186/s44147-024-00484-w","url":null,"abstract":"","PeriodicalId":55892,"journal":{"name":"Journal of Engineering and Applied Science","volume":"69 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141655497","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-10DOI: 10.1186/s44147-024-00481-z
Shubham Bansal, R. Yadav
{"title":"Effect of slip velocity on Newtonian fluid flow induced by a stretching surface within a porous medium","authors":"Shubham Bansal, R. Yadav","doi":"10.1186/s44147-024-00481-z","DOIUrl":"https://doi.org/10.1186/s44147-024-00481-z","url":null,"abstract":"","PeriodicalId":55892,"journal":{"name":"Journal of Engineering and Applied Science","volume":"22 14","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141659516","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-09DOI: 10.1186/s44147-024-00483-x
Xueting Wu, Jungyu Song
{"title":"Three-dimensional artistic design method of ceramic products based on recurrent neural network technology","authors":"Xueting Wu, Jungyu Song","doi":"10.1186/s44147-024-00483-x","DOIUrl":"https://doi.org/10.1186/s44147-024-00483-x","url":null,"abstract":"","PeriodicalId":55892,"journal":{"name":"Journal of Engineering and Applied Science","volume":"98 32","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141664190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-09DOI: 10.1186/s44147-024-00489-5
Trivikrama Raju C, Jakeer Hussain S, Yedukondalu G, M. Kolli
{"title":"An effective investigation of chatter prediction system on Al6061 alloy in an end milling process","authors":"Trivikrama Raju C, Jakeer Hussain S, Yedukondalu G, M. Kolli","doi":"10.1186/s44147-024-00489-5","DOIUrl":"https://doi.org/10.1186/s44147-024-00489-5","url":null,"abstract":"","PeriodicalId":55892,"journal":{"name":"Journal of Engineering and Applied Science","volume":"3 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141665521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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