Three different rotational speeds (800, 1000 and 1250 rpm) and traverse speeds of (0.42 mm/sec) at a constant taped pin have been employed to produce the stir zones generated from friction stir processing (FSP) of near eutectic Al- 14 wt.% Si alloy. The processed samples were thoroughly analyzed macroscopically and microscopically. The as-cast microstructure of eutectic (α Al+ Si) and primary Si were fragmented to produce spheroidization of small size of Si and deformed matrix. The stir zones showed an increase in hardness from around 45-50 Hv for as-cast to 40-65 depending on the variables applied. All the processed samples were characterized by advanced and retreated regions with large single piping defects formed mainly at the retreated region. High temperature spheroidization at 500 oC with two soaking times of 10 and 20 hrs was applied for the processed sample of 1000 rpm to investigate the effect of heat treatment on the silicon fragmentation and hardness. Growth and fragmentation of Si have taken place at soaking time of 10 hrs. At soaking time of 20 hrs noticeable microvoids and macrovoids were formed at the stir zones. Microhardness of both the advancing and the retreating regions decreased with increasing soaking time.
An environmentally begnin second derivative spectrometric approach was developed for the estimation of the dissociation constants pKa(s) of metformin, a common anti-diabetic drug. The ultraviolet spectra of the aqueous solution of metformin were measured at different acidities, then the second derivative of each spectrum was graphed. The overlaid second derivative graphs exhibited two isobestic points at 225.5 nm and 244 nm pointing out to the presence of two dissociation constants for metformin pKa1 and pKa2, respectively. The method was validated by evaluating the reproducibility of the acquired results by comparing the estimated values of the dissociation constants of two different strategies that show excellent matching. As we
... Show MoreIn the present paper, the authors introduce and investigates two new subclasses and, of the class k-fold bi-univalent functions in the open unit disk. The initial coefficients for all of the functions that belong to them were determined, as well as the coefficients for functions that belong to a field determining these coefficients requires a complicated process. The bounds for the initial coefficients and are contained among the remaining results in our analysis are obtained. In addition, some specific special improver results for the related classes are provided.
The accumulation of toxic elements in vegetables and melons grown in agriculture, Brassica rapa - turnip, Solanum lycopersicum - tomato, Citrullus lanatus - watermelon, Capsicum annuum - bell pepper, Daucus carota - carrots, Cucurbita pepo - pumpkin, Cucumis melo - melon, and also Prunus armeniaca - apricot from fruit trees were analyzed. The excess of maximum allowable concentrations in agricultural crops of the element As by 1.65-1.75, Cd - 1.6-2.3, Cr -1.2-2.35, Cu -1.6-3.3, Ni - 1.16-3.53, Pb - 1.54-3.08, Al - 1.36-3.5, Sb - 2.0-33, Se - 1.1-3.3 times was established. The maximum allowable concentration of mercury in vegetables and melons was equal to 0.02 mg/kg,
... Show MoreMethods of estimating statistical distribution have attracted many researchers when it comes to fitting a specific distribution to data. However, when the data belong to more than one component, a popular distribution cannot be fitted to such data. To tackle this issue, mixture models are fitted by choosing the correct number of components that represent the data. This can be obvious in lifetime processes that are involved in a wide range of engineering applications as well as biological systems. In this paper, we introduce an application of estimating a finite mixture of Inverse Rayleigh distribution by the use of the Bayesian framework when considering the model as Markov chain Monte Carlo (MCMC). We employed the Gibbs sampler and
... Show MoreThis article presents test results documentation for four grouted ground anchors embedded in sandy soil. Three anchors were trial, while one was a working anchor. One trial anchor is instrumented with eight resistance-type strain gauges glued on the corrugated pipe and embedded within the grouted body. An acceptance test was made for all anchors to determine the working load. Acceptance criteria suggested by the Post-Tensioning Institute were applied, and the working anchor did not pass the creep criterion, so it was taken out of service. The strain measurements indicated that the compression stresses were generated along the free length, while the tension stresses were generated alon
This work presents experimental research using draped prestressed steel strands to improve the load-carrying capacity of prestressed concrete non-prismatic beams with multiple openings of various designs. The short-term deflection of non-prismatic prestressed concrete beams (NPCBs) flexural members under static loading were used to evaluate this improvement. Six simply supported (NPCBs) beams, five beams with openings, and one solid specimen used as a reference beam were all tested as part of the experiment. All of the beams were subjected to a monotonic midpoint load test. The configuration of the opening (quadrilateral or circular), as well as the depth of the chords, were the varia
Because of inhalation of the volatile substances and unintended ingestion, the risk of health problems for fuelling employees exposed to gasoline vapours in gas stations is increased. Therefore, the goal of the study was to compare the oxidative stress state of healthy volunteers, who served as the control group, to Iraqi male fuelling staff, who served as the exposed groups. The levels of total oxidant status (TOS), total antioxidant status (TAS) and oxidative stress index (OSI), malondialdehyde (MDA), Uric acid (UA), and total peroxidase activity were measured. A total of 102 subjects divided into three groups according to the duration of fuel vapours exposure: 25 exposed for 1-10 years (G1), 50 exposed for 11-19 years (G2)
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