Capturing the temperature gradients of GMAW hardfacing processes by employing CFD and FEM simulation procedures

Hardfacing is carried out whenever a local improvement of the mechanical properties of metallic parts is demanded. In this regard, gas metal arc welding technology is one of the most popular choices. One decisive factor of the welded joint quality is governed by the heat affected zone. The present paper proposes a simulation methodology that can be employed for capturing the temperature gradients in any location of the base metal, when such information is required. The model was developed by using ANSYS Workbench simulation software and is based on coupled CFD and Transient Thermal analysis. In the first stage, a welded sample is subjected to 3D scanning for recreating its constitutive surfaces in a CAD environment. In the next stage, the convective heat transfer occurring due to the velocity of the shielding gas is captured by means of CFD analysis. Experimentally derived temperatures are employed for developing a transient thermal analysis, having defined the exterior heat transfer coefficient. In the last stage, the simulation results are verified in an arbitrary location of the base metal that is located outside the heat affected zone

The role of inflammation in age-related macular degeneration

Age-related macular degeneration (AMD) is a complex, chronic, and progressive disease which affects the macular area, being one of the leading causes of irreversible vision loss worldwide. Specific alterations of retinal structure occur at the macular level, which regarding its severity can range from the presence of drusen to the development of geographic atrophy or choroidal neovascularization. AMD has long been considered a degenerative disease, but new studies highlight the role of inflammation present both in the atrophic form and in the exudative form. The present review is based on comprehensive research on PubMed and Web of Science databases, and it aims to describe the inflammatory pathways involved in AMD onset and progression. Understanding the molecules involved in AMD pathogenesis, and their mechanism of action, is crucial because they can be both biomarkers with a predictive role in disease management, as well as potential therapeutic targets

Impact of risk factors on the evolution of severe acute pancreatitis

Introduction. Severe acute pancreatitis (SAP) is an acute inflammatory condition of the pancreas with increasing incidence and mortality rates in recent years. The aim of this study was to evaluate the impact of age, comorbidities, and different scoring systems on the complications and outcomes of SAP. Materials and Methods. A retrospective study was conducted on 161 patients diagnosed and treated for SAP at the Bucharest University Hospital in the intensive care unit (ICU), in the period 2014-2021. The impact of risk factors for the development of SAP, occurrence of complications (respiratory, cardiac, etc.), length of hospital stays and mortality was analyzed using several scores (BISAP, Ranson, Apache II and SOFA) or modified computed tomography severity index. Preexisting chronic conditions were assessed using the Charlson Comorbidity Index (CCI). Multivariate statistics and non-parametric univariate were calculated in statistical analysis. Odds ratios with 95% confidence intervals were used. Results. Risk factors such as age, diet, medication, alcohol consumption, genetic factors and patient comorbidities contribute significantly to the development of a severe form of acute pancreatitis with critical course and high mortality. Conclusions. In our study, CCI was the most important factor correlated with death and duration of ICU treatment

Is open surgery still part of the current treatment of inguinal hernias?

Inguinal hernia repair represents one of the most frequent pathologies with surgical addressability. From the multitude of surgical procedures, a limited number still keep their indication in the current treatment of hernias. Open surgery, the exclusive repair method until recently, is associated with laparoscopic techniques with benefits that are at least superposable on those in open repair. We conducted a study, analyzing several types of procedures in open surgery and comparing them to each other, but also with the TAPP approach, which is still at the beginning in our service. The non-mesh procedures scored poorly in terms of recurrence, the duration of the surgical intervention, and complications of the pain type, the Lichtenstein procedure was frequently associated with non-infectious inflammatory complications, and the TAPP, which is still in the learning curve, presented a prolonged duration of the surgical intervention. The Lichtenstein procedure maintains its usefulness and represents the most frequent technique for sanctioning inguinal hernia, the non-mesh processes, less used lately, are more frequently preferred in situations where hernia strangulation is associated with a septic complication. Open surgery hernia repair remains a feasible option in the era of minimal invasiveness, especially under the conditions of performing a tension-free technique, for specific categories of patients or surgical services remaining the first intention solution

Prostate Imaging Reporting and Data System score (PI-RADS) and Glutathione S-transferase P1 methylation status (GST-P1) in the diagnosis of prostate cancer patients with borderline PSA values

Objectives. The objective of this study was to evaluate the potential use of Prostate Imaging – Reporting and Data System version 2 (PI-RADS) in combination with Glutathione S-transferase P1 (GST-P1) expression for an improved diagnosis of prostate cancer, in patients with inconclusive values of prostate-specific antigen (PSA). Materials and Methods. The study was conducted on 80 patients for whom PSA values were evaluated and were found to be inconclusive (4-10 ng/ml). These patients underwent imagistic evaluation (PI-RADS), followed by transurethral prostate biopsy, with the evaluation of GST-P1 expression and histopathological examination (for diagnosis confirmation). Results. By combining the results of PI-RADS and GST-P1 the capacity of the tests to correctly identify healthy subjects, with an area under curve of 0,832 (95% CI 0.732–0.907), with a sensitivity of 73,25% and a specificity of 77,78%. Conclusions. PI-RADS lesions and GST-P1 methylation testing when PSA levels are in a “grey zone”, provide a better specificity and sensitivity by comparison through single testing. Testing patients with inconclusive PSA levels allows for a more accurate diagnosis and less over-diagnosis by non-invasive procedures, such as repeated biopsies

Optimal <i>H</i>₂ Moment Matching-Based Model Reduction for Linear Systems through (Non)convex Optimization

In this paper, we compute a (local) optimal reduced order model that matches a prescribed set of moments of a stable linear time-invariant system of high dimension. We fix the interpolation points and parametrize the models achieving moment-matching in a set of free parameters. Based on the parametrization and using the H2-norm of the approximation error as the objective function, we derive a nonconvex optimization problem, i.e., we search for the optimal free parameters to determine the model yielding the minimal H2-norm of the approximation error. Furthermore, we provide the necessary first-order optimality conditions in terms of the controllability and the observability Gramians of a minimal realization of the error system. We then propose two gradient-type algorithms to compute the (local) optimal models, with mathematical guarantees on the convergence. We also derive convex semidefinite programming relaxations for the nonconvex Problem, under the assumption that the error system admits block-diagonal Gramians, and derive sufficient conditions to guarantee the block diagonalization. The solutions resulting at each step of the proposed algorithms guarantee the achievement of the imposed moment matching conditions. The second gradient-based algorithm exhibits the additional property that, when stopped, yields a stable approximation with a reduced H2-error norm. We illustrate the theory on a CD-player and on a discretized heat equation

Şantierul arheologic Sucidava-Corabia / Les fouilles archéologiques de Sucidava-Celei de l’année 1979

Tudor Dumitru, Toropu Octavian, Tătulea Corneliu Mărgărit, Nica Marin. Şantierul arheologic Sucidava-Corabia / Les fouilles archéologiques de Sucidava-Celei de l’année 1979. In: Materiale şi cercetări arheologice, N°14 1980. A XIV-A sesiune anuală de rapoarte. pp. 357-363