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A vehicle's brake pedal transfers the force from a human being to the braking mechanism, and as such is considered as a safety component in the vehicle. In the past, vehicle weight-reduction initiatives resulted in a highly optimised design of steel brake pedal with an increased strength-to-weight ratio. However, any further reduction in the weight of the brake pedal is only possible by using combined, that is hybrid, materials. Hybrid technologies enable the design of lighter and cheaper brake pedals within the strict limits of the safety and technical requirements. This article presents an example of an innovative mechanical joint with a metal insert moulded into a polymer base structure that could be applied for a brake-pedal design. The metal insert contributes the required strength, while the polymer part provides the final form. However, the design of the metal insert not only provides the strength of the component, but also ensures the proper bonding of the metal-to-polymer joint. This article presents a comparison of the strength for simple and optimised forms of the metal insert within the hybrid joint. The strength comparisons were performed using numerical simulations, which were also experimentally validated. [ABSTRACT FROM AUTHOR]

The existing modified Locati step‐test was improved by pairing it with two evolutionary algorithms that were used to minimize the newly defined cost function that measures the deviation of the “best‐fit point” trace from the selected target number of load cycles. The main advantage of the new procedure over the conventional Locati step‐test is that the slopes and intercepts of the material's or the component's S‐N curves do not need to be known in advance in order to estimate the fatigue strength at a selected number of load cycles. The presented procedure was tested on two cases with a different target number of load cycles. The results indicate that the presented procedure is adequate to the conventional Locati step‐test procedure. [ABSTRACT FROM AUTHOR]

Due to their advantages-longer internal force delay compared to bulk materials, resistance to harsh conditions, damping of a wide frequency spectrum, insensitivity to ambient temperature, high reliability and low cost-granular materials are seen as an opportunity for the development of high-performance, lightweight vibration-damping elements (particle dampers). The performance of particle dampers is affected by numerous parameters, such as the base material, the size of the granules, the flowability, the initial prestress, etc. In this work, a series of experiments were performed on specimens with different combinations of influencing parameters. Energy-based design parameters were used to describe the overall vibration-damping performance. The results provided information for a deeper understanding of the dissipation mechanisms and their mutual correlation, as well as the influence of different parameters (base material, granule size and flowability) on the overall damping performance. A comparison of the performance of particle dampers with carbon steel and polyoxymethylene granules and conventional rubber dampers is given. The results show that the damping performance of particle dampers can be up to 4 times higher compared to conventional bulk material-based rubber dampers, even though rubber as a material has better vibration-damping properties than the two granular materials in particle dampers. However, when additional design features such as mass and stiffness are introduced, the results show that the overall performance of particle dampers with polyoxymethylene granules can be up to 3 times higher compared to particle dampers with carbon steel granules and conventional bulk material-based rubber dampers.

In this article, a response of the complex-phase high-strength steel SZBS800 was modelled by considering the strain-rate influence. The material's response was first measured with a series of standard tensile tests at lower strain rates. Higher strain rates were achieved using the unconventional test of shooting the ball into flat specimens. A viscoplastic formulation of the Cowper-Symonds material model was applied to consider the strain-rate effects. The parameters SIGY , p , and C of the material model were estimated using a step-wise procedure. First, rough estimates of the three parameters were obtained from the tensile tests using the grid search method. Then, the parameters p and C were fine-tuned using the reverse engineering approach. With the help of explicit dynamic simulations and all the experimental data, a multi-criteria cost function was defined and applied to obtain a smooth response function for the parameters p and C . Its optimum was determined by a real-valued genetic algorithm. The optimal values of the estimated parameters model the material response well, although a domain of optimum candidates spans two orders of magnitude for the parameter p and a few orders of magnitude for the parameter C .

Granular materials promise opportunities for the development of high-performance, lightweight vibration-damping elements that provide a high level of safety and comfort. Presented here is an investigation of the vibration-damping properties of prestressed granular material. The material studied is thermoplastic polyurethane (TPU) in Shore 90A and 75A hardness grades. A method for preparing and testing the vibration-damping properties of tubular specimens filled with TPU granules was developed. A new combined energy parameter was introduced to evaluate the damping performance and weight-to-stiffness ratio. Experimental results show that the material in granular form provides up to 400% better vibration-damping performance as compared to the bulk material. Such improvement is possible by combining both the effect of the pressure-frequency superposition principle at the molecular scale and the effect of the physical interactions between the granules (force-chain network) at the macro scale. The two effects complement each other, with the first effect predominating at high prestress and the second at low prestress. Conditions can be further improved by varying the material of the granules and applying a lubricant that facilitates the granules to reorganize and reconfigure the force-chain network (flowability).

In recent years, elastocaloric cooling has shown great potential as an alternative to vapor-compression refrigeration. However, there is still no existing elastocaloric device that offers fatigue-resistant operation and yet high cooling/heat-pumping performance. Here, we introduce a new design of an elastocaloric regenerator based on compression-loaded Ni-Ti tubes, referred to as a shell-and-tube-like elastocaloric regenerator. Our regenerator design, which can operate in both cooling and heat-pumping modes, enables durable operation and record performance with a maximum temperature span of 31.3 K in heat-pumping mode or maximum heating/cooling powers of more than 60 W, equivalent to 4,400 W/kg of the elastocaloric material (at temperature span of 10 K). In terms of both maximum performance metrics, these results surpass all previously developed caloric (magnetocaloric, electrocaloric, and elastocaloric) devices and demonstrate the enormous potential of compression-loaded elastocaloric regenerators to be used in elastocaloric devices for a wide range of cooling and heat-pumping applications., Competing Interests: The authors declare no competing interests., (© 2022 The Author(s).)

In real engineering applications, machine parts are rarely completely homogeneous; in most cases, there are at least some minor notch effects or even more extensive inhomogeneities, which cause critical local stress concentrations from which fatigue fractures develop. In the present research, a shift of the Coffin-Manson ε a - N material curve in a structure with random porosity subjected to dynamic LCF loads was studied. This allows the rest of the fatigue life prediction process to remain the same as if it were a homogeneous material. Apart from the cyclic σ - ε curve, which is relatively easy to obtain experimentally, the ε a - N curve is the second most important curve to describe the correlation between the fatigue life N and the strain level ε a . Therefore, the correct shift of the ε a - N curve of the homogeneous material to a position corresponding to the porous state of the material is crucial. We have found that the curve shift can be efficiently performed on the basis of numerical simulations of a combination of five porosity-specific geometric influences and the associated regression analysis. To model the modified synthetic ε a - N curve, five geometric influences of porosity by X-ray or μ -CT analysis are quantified, and then the porosity-adjusted coefficients of the Coffin-Manson equation are calculated. The proposed approach has been successfully applied to standard specimens with different porosity topography.

When wood is used as a structural material, the fact that it is a highly inhomogeneous material, which significantly affects its static and fatigue properties, presents a major challenge to engineers. In this paper, a novel approach to modelling the fatigue-life properties of wood is presented. In the model, the common inverse-power-law relationship between the structural amplitude loads and the corresponding number of load cycles to failure is augmented with the influence of the wood's mass density, the loading direction and the processing lot. The model is based on the two-parametric conditional Weibull's probability density function with a constant shape parameter and a scale parameter that is a function of the previously mentioned parameters. The proposed approach was validated using the example of experimental static and fatigue-strength data from spruce beams. It turned out that the newly presented model is capable of adequately replicating the spruce's S-N curves with a scatter, despite the relatively scarce amount of experimental data, which came from different production lots that were loaded in different directions and had a significant variation in density. Based on the experimental data, the statistical model predicts that the lower density wood has better fatigue strength.

The problem of characterizing the structural residual life is one of the most challenging issues of the damage tolerance concept currently applied in modern aviation. Considering the complexity of the internal architecture of composite structures widely applied for aircraft components nowadays, as well as the additional complexity related to the appearance of barely visible impact damage, prediction of the structural residual life is a demanding task. In this paper, the authors proposed a method based on detection of structural damage after low-velocity impact loading and its classification with respect to types of acting stress on constituents of composite structures using the developed processing algorithm based on segmentation of 3D X-ray computed tomograms using the rebmix package, real-oriented dual-tree wavelet transform and supporting image processing procedures. The presented algorithm allowed for accurate distinguishing of defined types of damage from X-ray computed tomograms with strong robustness to noise and measurement artifacts. The processing was performed on experimental data obtained from X-ray computed tomography of a composite structure with barely visible impact damage, which allowed better understanding of fracture mechanisms in such conditions. The gained knowledge will allow for a more accurate simulation of structural damage in composite structures, which will provide higher accuracy in predicting structural residual life.

Magnesium is one of the lightest metals for structural components. It has been used for producing various lightweight cast components, but the application of magnesium sheet plates is less widespread. There are two reasons for this: (i) its poor formability at ambient temperatures; and (ii) insufficient data on its durability, especially for dynamic loading. In this article, an innovative approach to predicting the fatigue life of the AZ31 magnesium alloy is presented. It is based on an energy approach that links the strain-energy density with the fatigue life. The core of the presented methodology is a comprehensive new model for tensile and compressive loading paths, which makes it possible to calculate the strain-energy density of closed hysteresis loops. The model is universal for arbitrary strain amplitudes. The material parameters are determined from several low-cycle fatigue tests. The presented approach was validated with examples of variable strain histories.

Background: Human metapneumovirus (HMPV) is a paramyxovirus with multiple genetic lineages that is a leading cause of acute respiratory disease. Several RT-PCR assays have been described based on limited available sequence data., Objectives: To develop a broadly reactive real-time RT-PCR assay for HMPV that allows for a rapid, sensitive, and specific detection in a clinical or research setting., Study Design: Three published assays for HMPV were modified based on analysis of multiple HMPV sequences obtained from GenBank. Original and modified assays were tested against prototype HMPV strains from each genetic sublineage, multiple isolates of HMPV from different years, a collection of clinical specimens, and commercial validation panels., Results: A number of potential sequence mismatches with diverse HMPV strains were identified. Modifications were made to oligonucleotides to improve annealing efficiency. Primers and probes based on newer sequence data offered enhanced detection of all subgroups, especially for low titer specimens. The new primers and probe detected multiple clinical isolates of HMPV collected over a twenty-year period. The modified assay improved detection of HMPV in a panel of clinical specimens, and correctly identified HMPV samples in two commercial validation sets., Conclusions: We report a modified real-time RT-PCR assay for HMPV that detects all genetic lineages with high sensitivity., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Pandemic influenza viruses often cause severe disease in middle-aged adults without preexisting comorbidities. The mechanism of illness associated with severe disease in this age group is not well understood. Here we find preexisting serum antibodies that cross-react with, but do not protect against, 2009 H1N1 influenza virus in middle-aged adults. Nonprotective antibody is associated with immune complex-mediated disease after infection. We detected high titers of serum antibody of low avidity for H1-2009 antigen, and low-avidity pulmonary immune complexes against the same protein, in severely ill individuals. Moreover, C4d deposition--a marker of complement activation mediated by immune complexes--was present in lung sections of fatal cases. Archived lung sections from middle-aged adults with confirmed fatal influenza 1957 H2N2 infection revealed a similar mechanism of illness. These observations provide a previously unknown biological mechanism for the unusual age distribution of severe cases during influenza pandemics.

In a post-marketing surveillance study of 752 patients suffering from urgent incontinence, mixed urgent-stress incontinence, reflex incontinence, urgency and enuresis were treated with propiverine hydrochloride. Clinical efficacy of propiverine hydrochloride was verified by the improvement of symptoms related to detrusor hyperactivity, hypersensitivity and hyperreflexia during a 12-week surveillance period: daytime and overnight urinary incontinence, as well as the frequency, nocturia, urgency in day time and at night decreased. These results are well demonstrated by decreased pad use and statistically significant decrease of Gaudenz urgency score during treatment, confirming the efficacy of propiverine hydrochloride already proved in clinical trials. The safety profile of propiverine hydrochloride displayed characteristic anticholinergic symptoms (dry mouth, accommodation disorders, constipation, tiredness, dizziness) with decreasing incidence during the 12-week treatment period. The residual urine volume decreased also. Serious adverse events were observed rarely and could be explained by the lack of consideration of contraindications, warnings and interactions with other drugs. The positive risk-benefit relationship of propiverine hydrochloride in the treatment of detrusor hyperactivity, hypersensitivity and hyperreflexia was reconfirmed in this post-marketing drug surveillance study.

Described report case of the patient after left nephrectomy, performed 18 years ago, for adenocarcinoma. Recently he has a simultaneous carcinoma of the bladder and the left ureter. Carcinoma of the bladder was treated with transurethral resection and electrocoagulation. Once checked, the hemorrhage was found from the left ureter, later, papilocarcinoma was diagnosed and the urethrectomy with the resection of the part of the wall of the bladder in the region of the estuary. Patient was in good condition 5 months after the operation. There is a review of others report cases.

At the urological department of the First Surgical Clinic, Faculty of general Medicine Charles University in Prague from January 1977 to December 1986 922 men were operated on account of benign obstruction of the cervix. Ninety-one patients, i.e. 9.8%, with some common signs were subjected to clinical analysis. The criterium for inclusion in the group was the finding of a not enlarged, through on palpation frequently altered prostate, the finding of a histological, endoscopic, X-ray and urodynamic examination. The common sign of these patients was the presence of the disease in young age, a prolonged persistence (up to 20 years) and the frequent presence of supravesical congestion, sometimes with a diverticulum of the urinary bladder. The cause of the disease was dyssynergy, urethrovesical hypertrophy of the poesterior commissure, atrophy of the prostate, subtrigonal hyperplasia of the prostate and a secondary contracture. A transurethral operation was performed in 64 patients, a transvesicalar one in 24 and in three a XY plastic operation was made.