113 research outputs found
Evaluation of Induced Settlements of Piled Rafts in the Coupled Static-Dynamic Loads Using Neural Networks and Evolutionary Polynomial Regression
Coupled Piled Raft Foundations (CPRFs) are broadly applied to share heavy loads of superstructures between piles and rafts and reduce total and differential settlements. Settlements induced by static/coupled static-dynamic loads are one of the main concerns of engineers in designing CPRFs. Evaluation of induced settlements of CPRFs has been commonly carried out using three-dimensional finite element/finite difference modeling or through expensive real-scale/prototype model tests. Since the analyses, especially in the case of coupled static-dynamic loads, are not simply conducted, this paper presents two practical methods to gain the values of settlement. First, different nonlinear finite difference models under different static and coupled static-dynamic loads are developed to calculate exerted settlements. Analyses are performed with respect to different axial loads and pile’s configurations, numbers, lengths, diameters, and spacing for both loading cases. Based on the results of well-validated three-dimensional finite difference modeling, artificial neural networks and evolutionary polynomial regressions are then applied and introduced as capable methods to accurately present both static and coupled static-dynamic settlements. Also, using a sensitivity analysis based on Cosine Amplitude Method, axial load is introduced as the most influential parameter, while the ratio l/d is reported as the least effective parameter on the settlements of CPRFs
Implementation of Linear Stability Theory on Hollow Cone-shaped Liquid Sheet
Surface instability of a swirling liquid sheet emanating from a centrifugal injector in presence of external and internal gas flows is studied in this paper. A three-dimensional flow for the liquid sheet and two-dimensional flows for external and internal gas flows are considered. The set of equations involved in this analysis differs from the earlier analyzes. In previous studies, a cylindrical liquid sheet has been considered to implement the linear theory but in this study, the linear stability theory is implemented on a cone-shaped liquid sheet for different cone angles. Actually more over than axial and tangential movements, the radial movements of liquid sheet and gas flows are considered in the present model. Due to complexity of the derived governing equations, semi-analytical and numerical methods were applied to solve them. The case study is oxidizer injector of rocket engines. Implementation of linear stability theory on a hollow cone-shaped liquid sheet better can predict instability phenomenon than the general linear stability analysis for this type of liquid sheets. The results show very close agreement with available experimental data
The effect of family-centered empowerment model on skill, attitude, and knowledge of multiple sclerosis caregivers
Materials and Methods: This clinical-trial study was done on 70 care givers of multiple
sclerotic patients who were divided into case and control groups. Family-centered
empowerment model was applied for three months and then the questionnaires regarding
skill, attitude, and knowledge of the participants were collected. The obtained data was
analyzed by means of SPSS software (version 11.5) and dedicational statistical tests at the
significant level of P< 0.05. Results: Independent T-test revealed that there was no ..
Design Optimization In A Conventional Tunnelling Project In Urban Area Using The Observational Method- Niayesh Road Tunnel In Tehran, Iran
Sharifzadeh, M. and Yasrobi, S. and Ghorbani, M. and Daiyan, M. 2014. Design Optimization in a Conventional Tunnelling Project in Urban Area using the Observational Method-Niayesh Road Tunnel in Tehran, Iran, in Negro, A. and CecÃlio, M. and Bilfinger, W. (eds), Proceedings of the World Tunnel Congress 2014 – Tunnels for a better Life, May 9-15 2014, p. 157. Foz do Iguaçu, Brazil: CBT/ABMS
General health and its association with sleep quality in two groups of nurses with and without shift working in educational centers of Iran University of Medical Sciences (IUMS
Background and aim: The health condition of nurses as caregivers influences the quality of care received by patients. To reach the maximum performance, nurses themselves need be health. Nurses, because of the nature of their career confront many types of stresses in their work environment and they are among people that are prone sleep disorder because of working in morning, evening, night and especially, rotation shifts. The aim of this study is comparison of the general health and sleep quality of nurses in two groups of without shift and with shift working in IUMS- 2006. Methods: It was a descriptive - analytical study. The setting was hospitals affiliated to IUMS. Five hundreds and twenty nurses were recruited using stratified random sampling. To survey the general health and sleep quality of nurses General Health Questionnaire - 28 and Pitsberg Sleep Quality Index tools were used. Results: Chi – Square test indicatod that there was a significant difference between general health of without shift and with shift workers, so that general health of without shift workers was better than rotation shift ones. The sleep quality of without shift nurses was also better than rotation shift ones (r=0.692, P<0.001). There was a direct correlation between general health state and sleep quality (P<0.001). Conclusion: Based of the finding of this study, appropriate and efficient managmant and careful planning of working shifts is suggest to reduce sleep disturbances in nurses. Promotion of nurse’s quality of sleep can promote their general health and eventually promotes the quality care of patients
Intracranial Aneurysm Rupture after SARS-CoV2 Infection : Case Report and Review of Literature
Background: SARS-CoV virus infection results in a dysbalanced and severe inflammatory response with hypercytokinemia and immunodepression. Viral infection triggers systemic inflammation and the virus itself can potentially cause vascular damage, including blood-brain barrier (BBB) disruption and alterations in the coagulation system, which may result in cardiovascular and neurovascular events. Here, we review the literature and present a case of COVID-19 infection leading to an aneurysmal subarachnoid haemorrhage (aSAH). Case Description: A 61-year-old woman presented with dyspnea, cough, and fever. She had a history of hypertension and was overweight with a body mass-index of 34. There was no history of subarachnoid hemorrhage in the family. Due to low oxygen saturation (89%) she was admitted into ICU. A chest CT showed a typical picture of COVID-19 pneumonia. The PCR-based test of an oropharyngeal swab was COVID-19-positive. In addition to oxygen support she was prescribed with favipiravir and hydroxychloroquine. She experienced a sudden headache and lost consciousness on the second day. Computer tomography (CT) with CT-angiography revealed a subarachnoid haemorrhage in the basal cisterns from a ruptured anterior communicating artery aneurysm. The aneurysm was clipped microsurgically through a left-sided standard pterional approach and the patient was admitted again to the intensive care unit for further intensive medical treatment. Post-operatively, the patient showed slight motor dysphasia. No other neurological deficits. Conclusion: Systemic inflammation and ventilator support-associated blood pressure fluctuations may trigger aneurysmal subarachnoid haemorrhage secondary to COVID-19 infection. COVID-19 infection could be considered as one of the possible risk factors leading to instability and rupture of intracranial aneurysm.Peer reviewe
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