Inverse Calculation of Timber-CFRP Composite Beams Using Finite Element Analysis

This study focuses on the flexural behavior of timber beams externally reinforced using carbon fiber-reinforced polymers (CFRP). Linear and non-linear finite element analysis were proposed and validated by experimental tests carried out on 44 timber beams to inversely determine the material properties of the timber and the CFRP. All the beams have the same geometrical properties and were loaded under four points bending. In this paper the general commercial software ANSYS was used, and three- and two-dimensional numerical models were evaluated for their ability to describe the behavior of the solid timber beams. The linear elastic orthotropic material model was assumed for the timber beams in the linear range and the 3D nonlinear rate-independent generalized anisotropic Hill potential model was assumed to describe the nonlinear behavior of the material. As for the CFRP, a linear elastic orthotropic material model was introduced for the fibers and a linear elastic isotropic model for the epoxy resin. No mechanical model was introduced to describe the interaction between the timber and the CFRP since failure occurred in the tensile zone of the wood. Simulated and measured load-mid-span deflection responses were compared and the material properties for timber-CFRP were numerically determined

Anti-spoofing using challenge-response user interaction

2D facial identification has attracted a great amount of attention over the past years, due to its several advantages including practicality and simple requirements. However, without its capability to recognize a real user from an impersonator, face identification system becomes ineffective and vulnerable to spoof attacks. With the great evolution of smart portable devices, more advanced sorts of attacks have been developed, especially the replayed videos spoofing attempts that are becoming more difficult to recognize. Consequently, several studies have investigated the types of vulnerabilities a face biometric system might encounter and proposed various successful anti-spoofing algorithms. Unlike spoofing detection for passive or motionless authentication methods that were profoundly studied, anti-spoofing systems applied on interactive user verification methods were broadly examined as a potential robust spoofing prevention approach. This study aims first at comparing the performance of the existing spoofing detection techniques on passive and interactive authentication methods using a more balanced collected dataset and second proposes a fusion scheme that combines both texture analysis with interaction in order to enhance the accuracy of spoofing detection

A Parametric Investigation of the Influence of Knots on the Flexural Behavior of Timber Beams

The presence of knots significantly influences the mechanical behavior of timber. This research presents a parametric finite element analysis of the effect of knot characteristics on the flexural capacity of timber beams. Parameters include knot radius, longitudinal and vertical positions, length, and diving angle. The generation of the FE model is based on a technique developed in a previous research stage. The validation of the model is done via bending tests on a set of beams as well as a number of independent research studies. The numerical model accurately recreates the three-dimensional geometry of the knot and related fiber deviations. The capacity of the beams under bending is evaluated via the Tsai–Wu failure criterion. Findings reveal that the presence of knots in the tension zone leads to an early tensile failure and insufficient utilization of compression capacity, the decrease of bending capacity may rise significantly (up to 39% in this investigation), the knot inclination may positively or negatively influence the behavior depending on the diving angle, and moderate knot length can be detrimental to flexural capacity

Impact of Rejuvenators Type on Physical Properties of Aged Asphalt Cement

Recycling can be considered as one of the measures of sustainable methods. The physical traits of the asphalt mixture under the influence of accelerated aging (Long and Short–Term) for asphalt concrete were assessed. Asphalt cement (40-50), aggregate with 12.5 mm nominal extreme size and limestone dust as filler of the mineral was used for the preparation of asphalt concrete mixture. At the optimum content of the asphalt and asphalt of 0.5 percent below and above the optimum value, specimens were prepared by using Marshall Method. Two types of polymers as recycling agents were used (Polyethylene of Low Density and Crumb Rubber) with (0.5, 1 and 1.5) % by weight of the binder. The indirect tensile test was used for the mixtures at 25 ºC and double punch test at 60 ºC. It was determined that the use of (asphalt binder mixed with rubber) as the agent of recycling showed improved performance than the other kind of recycling agent. The indirect tensile strength at 40 ˚C of the recycled mixture was higher than that the control mixture. Punching shear strength was decreased by 84 %, temperature susceptibility was decreased by 69.6 % and the resistance to moisture damage increases by3.3 % at optimum asphalt content

Effect of Superpave Short-Term Aging on Binder and Asphalt Mixture Rheology

This study aimed to evaluate the effect of Superpave short term aging period length and type of additive used in modifying the asphalt binder on the creep behavior of asphalt binder and asphalt mix. Hot-mix asphalt (HMA) specimens were prepared at optimum asphalt content using unmodified asphalt, or asphalt with 4% by weight of SBS or PE. The Universal Testing Machine was used to conduct dynamic creep tests. Tests results indicated that the effect of extending the aging period on creep deformation is highly dependent on type of additive used in preparing the asphalt mix. Extending the aging period more than three hours caused insignificant effect of creep behavior of control asphalt mixes. On the other hand, extending the aging period more than one hour caused insignificant effect of creep behavior of asphalt mixes prepared using SBS additive. While for mixes prepared using PE, the creep deformation continues to decrease as aging period increase

TatooineMesher: Anisotropic interpolation from 1D cross-sections and 2D channel mesher

Hydrodynamic

Incidence and risk factors for surgical site infection post-gynecological operations in a tertiary hospital in Egypt: a retrospective study

Background: Surgical site infection (SSI) is the most common complication of surgical procedures in gynecology and it poses a significant burden for both patients and healthcare systems. Our objective was determining the incidence and risk factors for SSI post-gynecological operations during the period of five years.Methods: A matched case-control study at Minia maternity university, Egypt where A total of 18772 cases had undergone different gynecological procedures. The 876 cases were complicated with SSI (SSI cases group) and 2 matched controls per case were chosen from the rest of the cases and served as the control group (n=1752 cases).Results: The overall incidence of SSI post-gynecological operations was 4.67% and post-hysterectomy was 7.57%. SSI group had a significantly higher number of cases with diabetes, obesity, high parity (>4), increased blood loss and those had prolonged duration of surgery compared to the control group (all p<0.01).Conclusions: The identified risk factors are crucial for risk stratification of SSI and prioritizing interventions to improve the outcome. These results could give a picture for SSI post-gynecological operations in our country and identifying these risk factors is crucial for risk stratification of SSI and prioritizing interventions to improve the outcome

SPECTROPHOTOMETRIC METHODS FOR DETERMINATION OF SOFOSBUVIR AND DACLATASVIR IN PURE AND DOSAGE FORMS

Objective: Two simple, sensitive and accurate spectrophotometric methods have been developed for the determination of sofosbuvir (SOF) and daclatasvir (DAC) in pure forms and pharmaceutical formulations. Methods: The proposed methods are based on the oxidation of SOF and DAC by a known excess of cerium(IV) ammonium nitrate in sulphuric acid medium followed by determination of unreacted cerium(IV) by adding a fixed amount of indigo carmine (IC) and alizarin red S (ARS) dyes followed by measuring the absorbance at 610 and 360 nm, respectively. The experimental conditions affecting the reaction were studied and optimized. Results: The beer’s law was obeyed in the concentration ranges of 0.2-3.0, 0.2-4.0 for SOF and 0.5-4.5 and 0.5-5.0 μg/ml for DAC using IC and ARS methods, respectively with a correlation coefficient ≥ 0.9991. The calculated molar absorptivity values are 2.354 × 104, 1.933 × 104 for SOF and 1.786 × 104 and 2.015 × 104 L/mol. cm for DAC using IC and ARS methods, respectively u. The limits of detection and quantification are also reported. Intra-day and inter-day precision and accuracy of the methods have been evaluated. Conclusion: The methods were successfully applied to the assay of SOF and DAC in tablets and the results were statistically compared with those of the reference method by applying Student’s t-test and F-test. No interference was observed from the common tablet excipients. The accuracy and reliability of the methods were further ascertained by performing recovery studies using the standard addition method

Molecular Diagnosis of Brucella species in Baghdad

Brucellosis is possess a significant public health problem in Baghdad. In this study, we investigated the potential role of the PCR assay in detection of Brucella species, from patients suspect to have brucellosis, using blood samples in both human and animal. To establish a PCR technique for diagnosis of active brucellosis in our samples, DNA extraction was carried out using a commercial kit, and a laboratory extraction procedure. PCR amplification was done using 1 set of primers: B4/B5 for Brucella species. Extraction of Brucella DNA using the commercial kit was successful. The laboratory extraction was successful and more economic. A total of 178 peripheral blood specimens were collected from patients with high suspected brucellosis, and 15 samples from animals. When PCR technique was applied to blood samples, 13 cases for patients blood and 9 cases for animals blood, were positive for Brucella species