Behavior Of Curves Research Articles

Experimental investigation of screwed beam-column connection using cold-formed steel back-to-back sections with gusset-plate

Fifteen tests have reported the experimental behavior of steel beam-column connections using cold-formed steel (CFS) sections with gusset plates attached to self-drilling screws. Using screws instead of bolts can be economical in cold-formed steel structures due to the nonexisting failure of bolts in tests. The aim of the study was to understand how gusset plate thickness, beam thickness, and stiffener use could affect screwed beam-column connections using cold-formed steel section behavior; experimental research using cantilever testing was carried out with full-scale specimens of the connections. The results presented here show which stiffeners can prevent the beam from collapsing at the gusset plate's end-point, but they cannot affect the failure modes. However, the stiffening cannot modify the failure mode; it does not affect the behavior and characteristic values of the moment-rotation curve. Additionally, the moment resistance significantly decreased in the beam thicknesses without stiffeners to less than 1.5 mm. Furthermore, the ductility of the joint with the thicknesses of the gusset plate (P) is 1.5 mm, and the C/P ratio (C is beam thickness) is less than 1, which decreased with the used stiffener in the test specimens. Thus, the gusset plate, beam thickness, and C/P ratio are essential in determining the failure mode shape and the moment resistance value. Additionally, the results presented here are compared with the literature.

The additive Perks distribution and its applications in reliability analysis

ABSTRACT In this paper, the Additive Perks Distribution (ADP) is presented; this distribution describes the behavior of the bathtub curve, which is one of the most deeply rooted concepts in reliability analysis. The proposed distribution is based on the sum of the positive and negative hazard rate functions of the Perks distribution. ADP’s statistical properties include Measures of Central Tendency, moments, moment generating function, statistical order, residual lifetime, reversed residual lifetime, Rényi entropy, time-varying, and life-stress relationship modeling presented. For estimating the ADP parameters, the Maximum Likelihood Method is used. On the other hand, the APD is tested in three case studies and compared with other distributions that can describe the failure rates in a bathtub curve. The results from the case studies showed that the APD is a good choice for describing the failure times in the shape of a bathtub curve.

Bioresorbable PPDO sliding-lock stents with optimized FDM parameters for congenital heart disease treatment

Stent implantation has been a promising therapy for congenital heart disease (CHD) due to better efficacy. Compared to permanent metal stents, bioresorbable polymer stents have shown a great advantage in accommodating the vascular growth of pediatric patients, but the application is still limited due to inferior radial strength. Here, bioresorbable poly(p-dioxanone) (PPDO) sliding-lock stents for CHD treatment were fabricated by fused deposition modeling (FDM). The effects of FDM processing parameters, including nozzle temperature, bed temperature, layer thickness, and printing speed, on the mechanical properties of PPDO parts were investigated to optimize the processing condition to enhance the radial strength of stents. Finite element analysis (FEA) was also used to evaluate the mechanical properties of stents. PPDO sliding-lock stents fabricated under optimized FDM parameters showed radial strength of 3.315 ± 0.590 N/mm, superior to benchmark commercial metal stents. Radial strength curve and compression behavior of PPDO sliding-lock stents were investigated. Results of FEA exhibited that strut width, shape of the mesh cell and surface coverage ratio had an impact on the compression force of PPDO sliding-lock stents. PPDO sliding-lock stents fabricated with optimized FDM parameters show favorable mechanical performance and meet the requirement of CHD treatment.

Curcumin/H2O2 photodynamically activated: an antimicrobial time-response assessment against an MDR strain of Candida albicans.

Human candidiasis is typically treated with antifungal drugs, but the rise of drug-resistant strains of Candida spp. poses a serious problem, making treatment difficult. At the same time, photodynamictherapy (PDT) has drawn increasing attention from researchers for its potential to effectively inhibit multidrug-resistant pathogenic fungi and for its low tendency to induce drug resistance. This study's goal was to examine how a multidrug-resistant oral isolate of Candida albicans responded to a PDT that used a curcumin/H202 formulation as a photosensitizer and was exposed to various light sources. A commercial product containing curcumin/H2O2 3% was used as a photosensitizer and evaluated in a PDT treatment that can use two different light sources: traditional irradiation with 7 W light at λ = 460 nm or a new, never evaluated, polarized light source of 25 W with a wavelength range of λ = 380-3,400 nm. The antimicrobial activity of these procedures was assessed on a clinical oral isolate of Candida albicans, in terms of agar susceptibility test, growth curve behavior, and biofilm inhibition. Both light sources were able to activate the photosensitizer formulation, suggesting a fungistatic activity vs. this C. albicans MDR strain. An interesting difference was observed in the cell-generation-time (CGTOD) after PDT treatment, where the polarized light was more active compared to the source of 460 nm. In fact, CGTOD was 16 and 8 hours, respectively. The PDT evaluated here presented an inhibition window time, a crucial point for clinicians, who could activate an additional prophylactic treatment to resolve the clinical management of Candida infections in the oral cavity.

Oxygen sensing performance improvement by the combination of narrowed electrospinning fibers and multi-cored phosphorescent photosensitizer: Strategy and performance comparison

Electrospinning fibers doped with phosphorescent Cu(I) complexes have been demonstrated as promising O2 sensing systems, but traditional oxygen sensing systems based on electrospinning fibers have low sensitivity (<10). In this work, three multi-cored phosphorescent Cu(I) probes were firstly synthesized and discussed via their single crystals and photophysical analysis. A long-lived lifetime of 7.9 μs with emission peaking at 441 nm and quantum yield of 0.45 was obtained. Time-dependent density functional theory (DFT) calculation was performed at RB3LYP/LANL2DZ level which revealed a metal-to-ligand-charge-transfer-based electronic transition in excited state, favoring oxygen sensing. Then narrowed electrospinning fibers (diameter<200 nm) were synthesized using a high-pressure pump. The Cu(I) probes were doped into these narrowed electrospinning fibers with three doping levels (5wt%, 10wt%, and 15wt%), so that sample specific surface area was increased to allow more collision chances with O2 molecules. A detailed comparison between normal fibers and narrowed fibers was performed. Our optimal sample showed sensitivity of 20.99 with a linear working equation of I0/I=0.656+0.198*[O2], R2=0.999. This value is by far the highest one among oxygen sensors based on phosphorescent Cu(I) complexes. The limit of detection was as low as 2.2% (O2%). Corresponding response and recovery time values were 7 and 20 seconds. It was found that using narrowed fibers as host was an effective way to improve oxygen sensing performance, showing higher sensitivity, linear calibration curve and faster response behavior.

Impact Analysis of Potential Induced Degradation on Crystalline Silicon Solar Cell Performance by Correlating Practical Diagnosis with MATLAB Simulation.

Extensive research on fault diagnosis is essential to detect various faults that occur to different photovoltaic (PV) panels to keep PV systems operating at peak performance. Here, we present an impact analysis of potential induced degradation (PID) on the current-voltage (I-V) characteristics of crystalline silicon (c-Si) solar cells. The impact of parasitic resistances on solar cell performance is highlighted and linked to fault and degradation. Furthermore, a Simulink model for a single solar cell is proposed and used to estimate the I-V characteristics of a PID-affected PV cell based on experimental results attributes. The measured data show that the fill factor (FF) drops by approximately 13.7% from its initial value due to a decrease in shunt resistance (Rsh). Similarly, the simulation results find that the fill factor degraded by approximately 12% from its initial value. The slight increase in measured data could be due to series resistance effects which were assumed to be zero in the simulated data. This study links simulation and experimental work to confirm the I-V curve behavior of PID-affected PV cells, which could help to improve fault diagnosis methods.

Artificial neural network modeling on the polymer-electrolyte aqueous two-phase systems involving biomolecules

Polymer-electrolyte aqueous two-phase systems (ATPS) have demonstrated their superior performance in the separation and purification of high-value biomolecules. However, these powerful platforms are still a major academic curiosity, without their acceptance and implementation by industry. One of the major obstacles is the absence of models to predict the partition of biomolecules in ATPS in an easy and predictive way. To address this limitation, modelling studies on the binodal curve behavior of polymer-electrolyte ATPS and the partitioning of biomolecules in these aqueous electrolyte solutions are carried out in this work. First, a comprehensive database targeting the studied systems is established. In total, 11,998 experimental binodal data points covering 276 polymer-electrolyte ATPS at different temperatures (273.15 K-399.15 K) and 626 experimental partition data points involving 22 biomolecules in 42 polymer-electrolyte ATPS at different temperatures (283.15 K-333.15 K) are included. Then, a novel modeling strategy that combines a well-known machine learning algorithm, i.e., artificial neural network (ANN) and group contribution (GC) method is proposed. Based on this modeling strategy, an ANN-GC model (ANN-GC model1) is built to describe the binodal curve behavior of polymer-electrolyte ATPS, while another ANN-GC model (ANN-GC model2) is developed to predict the partition of biomolecules in these biphasic systems. ANN-GC model1 gives a mean absolute error (MAE) of 0.0132 and squared correlation coefficient (R2) of 0.9878 for the 9,598 training data points, and for the 1,200 validation data points they are 0.0141 and 0.9858, respectively. Meanwhile, it also gives a MAE of 0.0143 and R2 of 0.9846 for the 1,200 test data points. On the other hand, ANN-GC model2 gives root-mean-square deviation (RMSD) of 0.0577 for 501 training data points, and for the 62 validation data points and 63 test data points their RMSD are 0.0849 and 0.0885, respectively. Furthermore, the obtained results also indicate that the tie-line length of polymer-electrolyte ATPS calculated from ANN-GC model1 can be directly used in ANN-GC model2 for predicting the partition performance coefficient of biomolecules in these ATPS. The developed models offer the possibility to predict the partition of biomolecules in ATPS without any requirement of experimental data. Based on the developed ANN-GC models, some high-performance ATPS are identified to partition four well-known biomolecules.

Tangent curves to degenerating hypersurfaces

Abstract We study the behaviour of rational curves tangent to a hypersurface under degenerations of the hypersurface. Working within the framework of logarithmic Gromov–Witten theory, we extend the degeneration formula to the logarithmically singular setting, producing a virtual class on the space of maps to the degenerate fibre. We then employ logarithmic deformation theory to express this class as an obstruction bundle integral over the moduli space of ordinary stable maps. This produces new refinements of the logarithmic Gromov–Witten invariants, encoding the degeneration behaviour of tangent curves. In the example of a smooth plane cubic degenerating to the toric boundary we employ localisation and tropical techniques to compute these refinements. Finally, we leverage these calculations to describe how embedded curves tangent to a smooth cubic degenerate as the cubic does; the results obtained are of a classical nature, but the proofs make essential use of logarithmic Gromov–Witten theory.

Investigation of exchange bias and magnetoresistance in the Si substituted Ni-Mn-In ribbon alloys

We have studied the effect of Si substituted Ni-Mn-In alloy on the exchange bias (EB) and Magnetoresistance (MR) and found that the Curie temperature of martensite phase increases with Si substitution and vanishes for × = 3 ribbon alloy. The splitting of ZFC and FC curve at low temperature confirms the exchange bias phenomenon in the ribbons. The step like behavior in the isothermal ZFC curve also confirms the exchange bias behavior. The coercive field initially increases with temperature and reaches a maximum value at 40 K, and then decreases with the increase of temperature confirms the vanishing of EB in the ribbons with the temperature. The large exchange bias field of 687 Oe is found in × = 1 ribbon at 5 K.. A large negative magnetoresistance of 22.4% is found at 260 K for × = 1 ribbon. The change in magneto resistance can be attributed to the super zone boundary nearby Fermi surface.

Three-state resistive switching effect in BiFeO3 thin films

Resistive switching (RS) memristor has been widely used in the in-memory computation systems. Due to the strong information processing capability and low area cost of the ternary logic, the development of the three-state RS memristor was promoted. Here, we demonstrate a three-state RS phenomenon on Pt/BiFeO3/SrRuO3 structure. After applying a positive voltage to the thin film for a period, an abrupt RS effect occurs, where the three-state RS behavior can be obtained. By analyzing the conduction mechanisms of the current-voltage curves and the behavior of the capacitance-voltage curves, the three-state storage capability of the memristor can be ascribed to the movement of oxygen vacancies and the trapping/detrapping of charge carriers at the interface. The ternary OR logic gate was also designed with three steps by using only one memristor.

Studies of Synthesis Temperature Effects on Cubic Lithated-Spinel to Layered Phase Transformation and Electrochemical Performance of LiMn0.5Ni0.5O2 Cathode Materials

Recently, our group has reported a novel Li-ion battery cathode, ‘LT-LiMn0.5Ni0.5O2’, where LT refers to its relatively low synthesis temperature (400 °C). By collecting high energy X-ray diffraction and high-angle, annular-dark-field (HAADF) scanning-transmission electron microscopy (STEM) data, we confirm that the LT-LiMn0.5Ni0.5O2 features a unique partially disordered rock salt structure with predominant lithiated-spinel-like character. The electrochemical data indicates that the Li/LT-LiMn0.5Ni0.5O2 cells shows good cycle stability when operate between 2.5-5.0V. The 1st cycle specific discharge capacity was determined to be 225mAh/g. Two distinct voltage plateaus can be identified at approximately at ~4.6 V and ~3.5 V during discharge. The ~1 voltage separation of the plateaus is caused by the octahedral and tetrahedral site energy difference during lithium extraction and insertion.1 The discovery of LT-LiMn0.5Ni0.5O2 not only expand the compositional space for the known lithated-spinel family but also provide a practical way to increase the operational capacity of traditional spinels such like LiMn2O4 and LiMn1.5Ni0.5O2.2-5 It is well known that when synthesized at 900°C, LiMn0.5Ni0.5O2 features a layered structure.6 The existence of lithated-spinel like LiMn0.5Ni0.5O2 at low temperature (400°C) immediately raise another question: How does the synthesis temperature affect the structure and electrochemical performance of LiMn0.5Ni0.5O2? We synthesized a series of different temperature of LiMn0.5Ni0.5O2 powders. By collecting high energy X-ray diffraction and high-resolution transmission electron microscopy (HR-TEM) data, we confirm that, the LiMn0.5Ni0.5O2 exhibits a lithated spinel → disordered layered → ordered layered structure transformation as temperature increase from 400-900 °C. The Rietveld refinements results also reveals a gradual decrease of the Li/Ni exchange ratio accompanied by the synthesis temperature changes. The evolution of specific discharge capacity for different temperature LiMn0.5Ni0.5O2 shows a parabola-like curve behavior with the lowest discharge capacity at 700 °C. This unique behavior is likely to be related to the diffusion channels reconstruction along with the structure changes. 3D diffusion channels are incorporated with 2D diffusion channels at low temperature (400°C) for lithated-spinel LiMn0.5Ni0.5O2. Within the middle temperature range (500°C-700°C), the 3D channels destroy rapidly while 2D diffusion channels are not well established due to the highly disorder ratio resulting in a decrease of capacity. At higher temperature (800-900°C), the 2D diffusion channels are more well established enabling an increase of the capacity. Shi, B.; Gim, J.; Li, L.; Wang, C.; Vu, A.; Croy, J. R.; Thackeray, M. M.; Lee, E., LT-LiMn 0.5 Ni 0.5 O 2: a unique co-free cathode for high energy Li-ion cells. Chemical Communications 2021, 57 (84), 11009-11012.Thackeray, M. M.; Lee, E.; Shi, B.; Croy, J. R., Review–From LiMn2O4 to Partially-Disordered Li2MnNiO4: The Evolution of Lithiated-Spinel Cathodes for Li-Ion Batteries. Journal of The Electrochemical Society 2022, 169 (2), 020535.Gummow, R.; Thackeray, M.; David, W.; Hull, S., Structure and electrochemistry of lithium cobalt oxide synthesised at 400 C. Materials research bulletin 1992, 27 (3), 327-337.Lee, E.; Blauwkamp, J.; Castro, F. C.; Wu, J.; Dravid, V. P.; Yan, P.; Wang, C.; Kim, S.; Wolverton, C.; Benedek, R., Exploring lithium-cobalt-nickel oxide spinel electrodes for≥ 3.5 V Li-ion cells. ACS applied materials & interfaces 2016, 8 (41), 27720-27729.Lee, E.; Kwon, B. J.; Dogan, F.; Ren, Y.; Croy, J. R.; Thackeray, M. M., Lithiated Spinel LiCo1–x Al x O2 as a Stable Zero-Strain Cathode. ACS Applied Energy Materials 2019, 2 (9), 6170-6175.Yang, X.-Q.; McBreen, J.; Yoon, W.-S.; Grey, C. P., Crystal structure changes of LiMn0. 5Ni0. 5O2 cathode materials during charge and discharge studied by synchrotron based in situ XRD. Electrochemistry communications 2002, 4 (8), 649-654

Radiobiological modeling of acute esophagitis after radiation therapy of head, neck, and thorax tumors: The influence of chemo-radiation.

The aim of this study was to evaluate the performance of various radiobiological models in predicting the occurrence of acute esophagitis (AE) during radiation therapy (RT) of head, neck, and thoracic tumors with concurrent and sequential chemotherapy. According to recent studies, the probability of AE following RT by normal tissue complication probability models is predictable. A total of 100 patients with nasopharynx, larynx, Hodgkin's lymphoma, spinal metastases, and oral cavity and lung tumors were included in the study. Half of these patients were treated by concurrent chemo-radiotherapy (Con. CRT) and the other half were treated by radiotherapy alone or sequential chemo-radiotherapy (RT + seq. CRT). Radiobiological models of several types were used as follows,: Lyman-generalized equivalent uniform dose (gEUD), Lyman-MED, log-logistic, logit, and logistic. Parameters were estimated using maximum likelihood estimation, and models were compared using Akaike information criteria. Based on follow-up data, the behavior of dose-response curves differed markedly between the Con. CRT and RT + seq. CRT groups. The best fit with clinical results was offered by the Lyman-MED model for the Con. CRT group and the Lyman-gEUD model for the RT + seq. CRT group. Depending on the model used, the parameter of D50 was considerably lower (up to three times) in the Con. CRT group compared to the RT + seq. CRT group. The incidence of AE significantly differed between the two treatment groups in all the models. New parameter estimates could be used for predicting the probability of acute esophagitis after chemo-RT.

Photovoltaic model parameters identification using Northern Goshawk Optimization algorithm

The massive integration of photovoltaic (PV) systems into electric power grids creates a slew of new issues in today's power systems. Accurate modeling of photovoltaic modules is critical in strengthening the characteristics of its systems in simulation assessments. Modeling such PV systems is represented by a nonlinear current-voltage characteristic curve behavior with numerous unknown parameters due to insufficient data in the cells' datasheet. This manuscript presents an application of a recently introduced optimization algorithm called Northern Goshawk Optimization (NGO) for parameter identification of the triple diode model of the PV module. Three commercial PV modules are utilized in this study to accomplish this task. These models are multi-crystalline structures like Photowatt-PWP201 and Kyocera KC200GT and mono-crystalline like Canadian Solar CS6K-280 M. The simulation results show the ability of the NGO to extract the model parameters accurately. Experimental validation of the estimated parameters using the NGO optimizer is accomplished and compared with the simulation results under various environmental conditions. The simulation results show the superiority of the NGO over competitive optimization algorithms in terms of convergence speed and accuracy. The NGO can reduce the cost function to 1.35E-05, 9.42E-05, and 0.000195 for the PWP-201, KC200GT, and Canadian Solar CS6K-M modules. Moreover, the robustness of the NGO is evaluated by the statistical analysis and the Wilcoxon rank test.

Multiple magnetic transitions and magnetocaloric effect of Tb4CoIn alloy

We report on the magnetic, magnetocaloric, thermal, and electrical transport properties of Tb4CoIn alloy, which crystallizes in two phases, Tb6Co2.1In0.8 (space group Immm) and Tb2In0.9Co0.1 (space group P63/mmc), respectively. The alloy reveals three successive magnetic transitions around T1 (163 K), T2 (50 K), and T3 (29 K), respectively, associated with paramagnetic to ferromagnetic transition and two sequential antiferromagnetic transitions. The low-temperature transition T3 follows the first-order magnetic behavior and exhibits the field-induced magnetic transition. Meanwhile, T2 and T1 are found to be second-order in nature which opens a possibility for hysteresis-free magnetocaloric application. The magnetocaloric properties are determined using different magnetocaloric figures of merits such as –ΔSM, ΔTad, RCP, and TEC (10). Additionally, the universal curve behavior in the isothermal entropy change unveils the variation in critical exponents around T1 and T2 due to the magnetic inhomogeneity in the alloy. Besides, the electrical transport properties of the metallic alloy denote the maximum magnetoresistance of −10% around T1.

Epidemiological behavior of the COVID-19 contamination curve in Brazil: Time-series analysis.

Brazil is experiencing the greatest episode of sanitary collapse ever known in the country’s history. Therefore, the relevance of this study is highlighted for the scientific advance of the epidemiological behavior of the virus in Brazil, enabling the development of analyses and discussions on the factors that influenced the high rates of contamination by SARS-CoV-2 in the country. Given the above, this study aims to analyze the epidemiological behavior of the COVID-19 contamination curve by epidemiological weeks (EW), in the years 2020–2021, in Brazil. This is an ecological study of time series, prepared using information collected through secondary means. The country of origin of the study is Brazil, and its main theme is the number of people infected during the COVID-19 pandemic, this being the dependent variable of the study. The data has been analyzed from February 23, 2020, when the first case was confirmed in Brazil, to January 1, 2022. In 2021, the country’s graph shows an exponential growth, reaching a peak of approximately 250 new cases per 100,000 inhabitants in the 12th EW. This data represents the highest rate of the pandemic in Brazil, and did not vary significantly for the next twelve weeks. Thus, it was identified that Brazil was severely impacted by the new coronavirus, considering the high rates of confirmed cases of the virus in the country, the low adherence of the population to preventive measures, the late start of mass vaccination in the Brazilian population, and the lack of structure in the health system, which was not appropriately prepared for the high demand generated by COVID-19.

Experimental and Numerical Investigation on Seismic Performance of RC Exterior Beam-Column Joints with Slabs

The effect of a cast-in-place slab on the beam-column joint at beam ends in reinforced concrete (RC) structures under earthquake attacks has not been fully understood, and therefore, it is not manifestly addressed to some of the design criteria or specifications. Consequently, the contribution of slab to the seismic resistance of structures is often ignored or just included in an approximate manner. In this study, the experiment of two 1/2-scaled exterior beam-column joints without slabs and three 1/2-scaled joints with slabs under the combination of quasi-static repeated cyclic loading and constant axial force was carried out to investigate the effect of the cast-in-place slab on the seismic performance of exterior beam-column joints. The results show that for specimens EBCJ1 and EBCJ2 without slab, the decline was approximately 5%, while for specimens EBCSJ1 and EBCSJ3, the decline in the load is obvious and approximately more than 10%. For specimen EBCSJ2, which exhibited a slightly different behavior in the hysteresis curves, the maximum carrying capacity reached at the displacement of 70 mm during the first cycle. The cast-in-place slab has different effects on the failure mechanism and load transfer mechanism of the exterior beam-column joint, which depends on the column-beam moment strength ratio in the loading protocol. The slab has a positive effect on the energy dissipation capacity of the joint but has a negative effect on the load carrying capacity. In addition, finite element (FE) analysis of the tested specimens was conducted. The FE numerical models were established based on the construction information and loading conditions from the experiment and then validated by comparing them with the experimental observation.

Experimental and modeling study of hydrophobic associative polyacrylamide for enhanced oil recovery in carbonate reservoir

In this study, hydrophobic associative polyacrylamide (HAPAM) was used in conjunction with the chemical flooding technique in a low-permeability carbonates reservoir. To test the efficacy of the proposed method, both a model and an experiment were created. Experiments were run to compare the relative permeability (Kr) curves, oil recovery rates, and rheological, physical, aging time, and petrophysical features of brine water and polymer flooding in a core. The purpose of these tests was to show how HAPAM can be used to boost oil recovery. Computer Modelling Group (CMG), a simulator, was then used. An oil-and-brine (or HAPAM solution) grid in three dimensions (3D) was developed. The validity of the suggested simulator was established by comparing its results to those obtained from commercial software and from the majority of brine or polymer flooding experiments. The developed simulator was used to undertake additional research into the non-Newtonian flow of brine or polymer solution in porous media. The experimental consequences indicated that the polymer solution has a shear thinning viscosity curve and flow behavior index. Shear thinning, viscosity, shear resistance, aging time, density, surface tension, and interfacial tension, and the water wet relative permeability curve are all improved by the adding 1500 ppm HAPAM to brine water. Moreover, oil recovery was about 80%. There was a strong agreement between the results of the modeling study and the experiments.

Harmonization and Validation of Jiles–Atherton Static Hysteresis Models

The aim of the proposed paper is to harmonize the Jiles–Atherton (J–A) static hysteresis loop models presented by different authors at different publication dates. The reviewed papers, which explain the hysteresis loop model of magnetic materials originally developed by Jiles are taken into consideration due to their different variable nomenclature and even physical meaning. Inconsistency between Jiles’ referenced works is shown and the consequences are presented as differences between BH curve behaviors and, on the application level, as differences in calculated static hysteresis losses. The harmonization of J–A hysteresis models is presented and confirmed by numerical calculations and measured data.

Experimental and parametric study of a novel braced system to improve seismic performance

Concentrically braced frames have high stiffness, but show poor ductility in terms of the buckling of compressive member. Using the yielding dampers, of which the knee-joints are a part, can improve the seismic performance of steel frames. The bracing components in this system disperse energy by adhering to the knee joint and then yielding. The role of the bracing members is to provide rigidity, while the function of the knee member is to produce ductility similar to a yielding damper. These steel dampers are inactive and installed at the connection of brace to the frame. We obtained new results by combining Y-shaped braces with knee members. In this regard, three proposed bracing frame specimens were experimentally tested at the structural laboratory. Furthermore, all of the three laboratory specimens were modeled and validated in ABAQUS finite element software, and the results confirm the optimal performance of this seismic system along with energy absorption and appropriate behavior in the stability of this design. Moreover, it shows a good capacity for energy dissipation and the knee element starts the energy absorption process faster at lower frame displacements. It increases the durability of structure against lateral loads and less force is applied to the main elements of the structure. Using a knee bracing system can be a good alternative to the brace system in terms of its ease of replacement. Reasonable agreement with the experimental results is observed. The behavior of deformation-force hysteresis curves gives good results that, the experimental and parametric experiments showed that this system will have a lot of force adjustment.

In-situ neutron diffraction study on a dislocation density in a correlation with strain hardening in Al–Mg alloys

It is well known that variations of alloy and microstructural parameters i.e., alloy composition and grain size are favorable ways to improve the mechanical properties in non-heat-treatable aluminum alloys including Al–Mg alloys. It leads to a change in stress-strain curve behaviors. The flow stress is mainly correlated with dislocation interactions. In this study, in-situ neutron diffraction experiment was conducted to study evolution of dislocation density and characteristics during tensile deformation of Al–Mg. The dislocation density and related characteristic i.e., dislocation rearrangement were quantitatively analyzed by using neutron diffraction line profile analysis with using Convolution Multiple Whole Profile (CMWP) method. Variations of solute (Mg) contents and grain sizes in Al–Mg were investigated in a correlation with the dislocation densities and dislocation interactions. The higher Mg content and smaller grain size resulted to higher dislocation density and, consequently, higher flow stress and strain hardening rate.