Performance of Isolated Footing with Several Corrosion Levels under Axial Loading

This research aims to illustrate the corrosion process and its effect on the deterioration of reinforced concrete (RC) isolated footings using a small-scale model (1/8) and present the results of a prototype-scale study using a numerical model with different concrete depths and corrosion levels under axial load. The experimental program consisted of testing five small-scale (1/8) model RC isolated footings under axial loading after subjecting them to accelerated corrosion tests with a constant current. The main variable in the small-scale sample test was the corrosion level. This study presents an experimental approach, using the constant current method and the finite element method (FEM) with the ABAQUS package, to examine its effect on the axial load behavior under different corrosion ratios, which were 0%, 4.21%, 9.11%, 24.56%, and 30.67%. On the prototype scale, the variables were the corrosion level and the RC depths of 300 mm, 400 mm, and 500 mm. The results indicated that the average deviation in ultimate load between the experimental and FEM outcomes for the small-scale was below 5.6%, while the average deflection deviation was 6.8%. Also, the study found that an increase in the depth of the RC footing and corrosion ratio led to a more pronounced impact of the cracking pattern in the concrete and corroded bars, as well as a greater difference in the failure load. The experimental results suggest that the proposed numerical model is accurate and effective. These findings have important implications for the evaluation of isolated footings affected by corrosion damage using FEM, and can help inform decisions related to their design and maintenance. The failure loads of non-corroded footings with different depths were compared with the ECP-203 provisions of the 2018 Egyptian Code, and how corrosion ratios can be simulated by numerical models. The percentage variation between the design loads by code and the numerical loads by ABAQUS for controlled footings with thicknesses of 300, 400, and 500 mm was found to be 73%, 80%, and 78%, respectively. Using the derived relationship, the equivalent corrosion ratio percentages were 23.8%, 20.2%, and 32%, respectively. Doi: 10.28991/CEJ-2023-09-06-011 Full Text: PD

Structural Behaviour Of Asymmetrically Designed Timber-Concrete Hybrid Buildings With Different Roof Materials Subjected To El Centro Earthquake Excitations

Buildings are susceptible to earthquake disaster if the seismic loading is not considered in the design. Irregular buildings have been proven to perform badly during earthquake events. Due to lack of investigation on asymmetrical timber-concrete hybrid building under earthquake loading, a 1/4 scale of this type of building model was tested seismically using a unidirectional shake table. Six structural model frequencies varied by using diagonal wooden braces and steel cables were examined, which are 5.88 Hz, 4.55 Hz, 3.85 Hz, 3.33 Hz, 2.70 Hz, 2.50 Hz. Two different roof materials namely heavy metal roof and clay roof tile were considered for the building models with frequencies 3.85 Hz and 2.70 Hz. The model was subjected to El Centro ground motion excitation scaled to 0.08 g, 0.16 g, 0.24 g, 0.32 g resembling 25%, 50%, 75%, and 100% of the ground motion strength, respectively. Seven LVDTs and nine accelerometers were used to measure the seismic response of the model during the shake table test for displacement and acceleration, respectively. The change of roof material shows a clear effect on the seismic responses in terms of acceleration and relative displacement. Heavier roof material shows larger amplitudes across the maximum displacement time history, but a clear decrease in acceleration response for the roof level as compared with lighter roof material. Global deformation and acceleration amplification factors were obtained and evaluated. The relationships between the maximum roof displacement and PGA, and the maximum roof displacement and building frequency were established. The maximum displacement of the model is the highest when the natural building frequency is close to the predominant frequency of El Centro ground motion. A prediction equation for the maximum roof displacement relating the peak ground displacement and building frequency was then proposed

DeVega versus ring annuloplasty in severe functional tricuspid insufficiency and their impact on the right ventricle

Background: Functional tricuspid valve regurgitation secondary to left-sided valve disease is common. DeVega repair is simple, but residual regurgitation with subsequent impairment of the right ventricular function is a concern. This study aims to compare tricuspid valve repair using DeVega vs. ring annuloplasty and their impact on the right ventricle in the early postoperative period and after six months. Methods: This is a prospective cohort study of 51 patients with rheumatic heart disease who underwent tricuspid valve repair for secondary severe tricuspid regurgitation. Patients were divided into two groups: group A; DeVega repair (n=34) and group B; ring annuloplasty repair (n=17). Patients were assessed clinically and by echocardiography before discharge and after six months for the degree of tricuspid regurgitation, right ventricular diameter and tricuspid annular plane systolic excursion (TAPSE). Results: Preoperative echocardiographic assessment showed no difference in left ventricular end-systolic diameter, end-diastolic diameter, ejection fraction and right ventricular diameter, however; group A had significantly better preoperative right ventricular function measured by TAPSE (1.96 ± 0.27 vs1.75 ± 0.31 cm; p=0.02). Group B had significantly longer cardiopulmonary bypass time (127.65 ± 13.56 vs. 111.74 ± 18.74 minutes; p= 0.003) and ischemic time (99.06 ± 11.80 vs. 87.15 ± 16.01 minutes; p= 0.009). Pre-discharge, there was no statistically significant difference in the degree of tricuspid regurgitation, but the right ventricular diameter was significantly lower in group B (2.66 ± 0.41 and 2.40 ± 0.48 cm; p=0.049). After six months of follow up, the degree of tricuspid regurgitation (p= 0.029) and the right ventricular diameter were significantly lower in the ring annuloplasty group (2.56 ± 0.39 and 2.29 ± 0.44 cm; p=0.029). Although there was a statistically significant difference in preoperative TAPSE, this difference disappeared after six months. Conclusion: Both DeVega and ring annuloplasty techniques were effective in the early postoperative period, ring annuloplasty was associated with lesser residual regurgitation and better right ventricular remodeling in severe functional tricuspid regurgitation than DeVega procedure after 6-months of follow up

Finite element modeling and behavior analysis of axially comprised circular dual tube columns filled with concrete

CFDST is an abbreviation that stands for concrete-filled columns that have a dual steel tube. In the past few years, there has been debate on the possibility of using these types of columns. As a consequence of this, the objective of this work is to develop and validate material modeling approaches that are considered to be suitable for use with concrete-filled columns (CFT) that have been exposed to axial compression loads. Using the ABAQUS program as the nonlinear finite element, the suggested models are evaluated by doing a comparison study with the experimental data. This analysis is carried out in order to validate the models. The models are supported by this investigation. In addition, parametric investigations are carried out in order to evaluate the influence that the different strengths of the concrete have on the axial behavior of circular CFDST stub columns. This is done so that a conclusion may be drawn on the significance of the influence

Prevalence of Cytomegalovirus infection among Egyptian patients with fever of unknown origin

Background: Diagnosis of prolonged febrile illness of unknown origin (FUO) is challenging even with the advances in the diagnostic techniques. As common as the infection with cytomegalovirus (CMV) is, most health care providers would not suspect CMV infection as a cause of FUO unless mononucleosis syndrome is evident. The aim of this study is to investigate the rate of CMV infection among patients with FUO and shed light on IgG avidity as a diagnostic tool.  Patients and methods: Two hundred and twenty three (223) immune competent patients with FUO were included in our study. They were subjected to all routine laboratory investigations, fever agglutinins, tuberculin and abdominal ultrasound along with IgG and IgM for CMV and IgG avidity test. Results:  This study shows that the 92.8% of the overall studied population were positive for CMV IgG. However, only 74(33.2%) of the studied population was found positive for IgM. Only one patient had positive IgM with negative IgG. IgG avidity was high in almost all of them. Only 3 patients showed low IgG avidity denoting that they have primary infection. Conclusion: CMV infection was found to be the cause of 33.2% of prolonged febrile illness experienced by immuncompetent adults. Only 1.8% of patients had primary CMV infection and the majority of them had detectable IgG level and were diagnosed with primary infection depending mainly on IgG avidity test

Detection of Lying Electrical Vehicles in Charging Coordination Application Using Deep Learning

The simultaneous charging of many electric vehicles (EVs) stresses the distribution system and may cause grid instability in severe cases. The best way to avoid this problem is by charging coordination. The idea is that the EVs should report data (such as state-of-charge (SoC) of the battery) to run a mechanism to prioritize the charging requests and select the EVs that should charge during this time slot and defer other requests to future time slots. However, EVs may lie and send false data to receive high charging priority illegally. In this paper, we first study this attack to evaluate the gains of the lying EVs and how their behavior impacts the honest EVs and the performance of charging coordination mechanism. Our evaluations indicate that lying EVs have a greater chance to get charged comparing to honest EVs and they degrade the performance of the charging coordination mechanism. Then, an anomaly based detector that is using deep neural networks (DNN) is devised to identify the lying EVs. To do that, we first create an honest dataset for charging coordination application using real driving traces and information revealed by EV manufacturers, and then we also propose a number of attacks to create malicious data. We trained and evaluated two models, which are the multi-layer perceptron (MLP) and the gated recurrent unit (GRU) using this dataset and the GRU detector gives better results. Our evaluations indicate that our detector can detect lying EVs with high accuracy and low false positive rate

Role of serum tumour necrosis factor alpha and its soluble receptors in predicting acute renal allograft rejection

Tumour necosis factor alpha (TNF-?) is known to be involved in pathogenesis of acute renal allograft rejection. However, measurement of cytokine serum levels alone are not a reliable index of acute rejection episodes. TNF-?induces the release of soluble receptors (TNF-SR55 and TNF-SR75) that have an inhibitory activity and catabolized by the kidney.Twenty nine transplant recepients were studied and compared to ten healthy controls. TNF-?, TNF-SR55 and TNF-SR75 were measured before and after renal transplantation. The mean pre-transplantation values were 26.3 9.7 pg/ml, 28.2 8.3 and 42.5 11.1 ng/ml respectively. According to post-transplant course patients were divided into 3 groups. Group I (stable transplant group: no= 17): The mean level of TNF-?value was 7.5 4.6 pg/ml, TNF-SR55 6.4 4.7 and TNF-SR75 12.5 8 ng/ml (p NS). Group II (acute allograft rejection group: no = 8): The mean values were 37.2 16.2 pg/ml, 16.9 9.6 and 30.9 13.4 ng/ml respectively (p< 0.05). Group III cyclosporine (CS) nephrotoxicity group: no= 4): The mean level of TNF-? was 9.9 2.1 pg/ml with a highly significant increase in its receptor values (9.4 1.0 & 21.2 6.8 ng/ml; vs 5.5 1.2 & 12.4 4.8 ng/ml respectively (P< 0.01). To improve the predictive value of this cytokine and its receptors,we calculated the ratios of TNF-a to both receptors (SR55-SR75). During acute rejection episode, the ratio values tocontrol were 2.4 0.6 vs 1.4 0.7 and 1.3 0.5 vs 0.7 0.4 respectively (P< 0.01). However, these ratios did not change significantly from control group during CS nephrotoxicity 1.5 0.5 vs 2.0 0.7 and 0.5 0.3 vs 0.9 0.2 respectively (p>0.05). Thus, TNF-? and its soluble receptor levels might be of diagnostic value in renal allograft rejecion.In conclusion: 1) TNF-? and its soluble receptors are highly increased during hemodialysis. 2) There is no significant difference between healthy controls and patients with stable grafts. 3)There is highly significant increase of TNF-? and its receptors during acute rejection episodes and the day (R-2) prerejection in contrast to internal controls. 4) There is insignificant decrease of TNF-? during CS nephrotoxicity with highly significant increase of TNF-SR55, TNF-SR75 when compared to internal controls. 5) The ratios of TNF-?to SR55 & SR75 showed highly significant increase during acute rejection episodes and insignificant decrease during CS nephrotoxicity when compared to internal controls

Clinical and echocardiographic evaluation of patients undergoing total leaflets preservation during mitral valve replacement; Does it make a difference?

Background: The effect of anterior and posterior leaflet preservation on left ventricular function after mitral valve replacement is still the subject of ongoing research. The objective of this study is to analyze the early outcomes of total leaflets preservation compared to posterior and non-leaflet preservation during mitral valve surgery on cardiac function and dimensions measured by echocardiography and on the clinical outcomes.Methods: This prospective cohort study recruited 155 patients who had mitral valve replacement (MVR) from April 2016 to March 2018 at Assiut University Hospital. Patients were divided into three groups according to the technique of leaflets preservation; Group I (no leaflet preservation-N-MVR), Group II (total leaflet preservation- T-MVR) and Group III (posterior leaflet preservation-P-MVR). Patients who underwent redo mitral valve replacement (MVR) or those with endocarditis and had combined coronary artery bypass grafting with the MVR were excluded from the study.Results: There were nine early deaths (6%); eight patients were in Group I (N-MVR). Causes of mortality were massive intracranial hemorrhage (n= 2) and left ventricular failure (n=6). One patient died in Group III (P-MVR) from intracranial hemorrhage (1.3%). Hospital stay was significantly longer in N-MVR group compared to T-MVR and P-MVR (10.6±2.13 days in N-MVR group; p= 0.03 and 0.011 respectively). Postoperative low cardiac output occurred in all patients in N-MVR group. Left ventricular function (ejection fraction= 61.28±6.02%) and dimensions (end-diastolic diameter= 5.18±0.69 mm, end-systolic diameter= 3.58±0.78 mm) improved significantly in total leaflets preservation group.Conclusion: Leaflet preservation during mitral valve replacement was associated with improved clinical and echocardiographic outcomes. Non-leaflets preservation increased the risk of postoperative complications and length of hospital stay. Leaflet preservation is recommended as the standard approach during mitral valve replacement