Nova metoda izoliranja osnovne komponente signala zasnovana na transformaciji elementarnog vala

In this paper, a new method is proposed for improving the fundamental extraction by wavelet transform. This method uses the discrete wavelet transform (DWT), FIR filter and inverse discrete wavelet transform (IDWT). In the proposed method, frequency interference is allowed to occur at the extracted frequency bands by DWT. DWT output signal is filtered by FIR then the IDWT is used to reconstruct the filtered signal. This process improves the quality of extracted fundamental component and transient response. To verify the validity of the proposed method, the electric distribution system of electric arc furnaces (EAFs) of Mobarakeh Steel Company is simulated in MATLAB software. Finally the fundamental component of the voltage of point of common coupling (PCC) is extracted by proposed method and DWT and IDWT method.U radu je predložena nova metoda za unaprjeđenje određivanja osnovne komponente signala korištenjem transformacije elementarnog vala. Metoda koristi diskretnu transformaciju elementarnog vala (DWT), FIR filter i inverznu iskretnu transformaciju elementarnog vala (IDWT). Metoda dopušta interferenciju s DWT u frekvencijskom rasponu osnovne komponente. Izlazni DWT signal filtriran je pomoću FIR-a, a zatim se primjenjuje IDWT za rekonstrukciju filtriranog signala. Ovaj proces poboljšava kvalitetu određene osnovne komponente i odziva prijelazne pojave. Za provjeru vjerodostojnosti predložene metode, u MATLAB programu simuliran je sustav za elektrodistribuciju elektrolučne peći (EAF) za poduzeće Mobarakeh Steel Company. Konačno, osnovna komponenta napona točke zajedničkog spoja (PCC) određena je predloženom metodom uz DWT i IDWT

The occurrence of antibiotic resistance, ESBLs, MBL and NDM-1 in Uropathogenic Escherichia coli in Central part of Iran

Broad-spectrum β-lactamase enzymes capable of destroying the antibiotics of β-lactam, cephalosporin, and Metallo-β-lactamase enzymes can also deactivate all β-lactams and carbapenems. This study aimed to determine ESBLs and MBLs enzymes and the frequency of NDM-1 gene­. In this study, 200 Escherichia coli isolates of women with urinary tract infection were collected (100 inpatients and 100 outpatients). Minimum inhibitory concentration (MIC) for ceftazidime and meropenem was determined by E-test. A phenotypic confirmation test was used to detect ESBL enzymes. MBLs production was performed with modified Hodge test (MHT) and EDTA disk synergy (EDS) test. PCR was used for detecting the presence of NDM-1 gene. From 200 isolates, 93 isolates produce ESBL enzymes. Overall, 97 isolates were resistant to ceftazidime, and 38 isolates resistant to meropenem. The results of the MHT and EDS positive tests were 41 and 16 isolates, respectively. NDM-1 was not found in any of the patients. The prevalence of E. coli isolates producing both ESBLs and MBLs enzymes, is a serious threat to clinical infections. Accordingly, for the control and treatment of these strains, rapid and accurate identification can be greatly helpful

Through-Thickness Residual Stresses, Microstructure, and Mechanical Properties of Electron Beam-Welded CA6NM Martensitic Stainless Steel after Postweld Heat Treatment

In this study, the integrity of electron beam- (EB-) welded CA6NM—a grade of 13% Cr-4% Ni martensitic stainless steel—was assessed through the entire joint thickness of 90 mm after postweld heat treatment (PWHT). The joints were characterized by examining the microstructure, residual stresses, global mechanical properties (static tensile, Charpy impact, and bend), and local properties (yield strength and strain at fracture) in the metallurgically modified regions of the EB welds. The applied PWHT tempered the "fresh" martensite present in the microstructure after welding, which reduced sufficiently the hardness (<280 HV) and residual stresses (<100 MPa) to meet the requirements for hydroelectric turbine assemblies. Also, the properties of the EB joints after PWHT passed the minimum acceptance criteria specified in ASME sections VIII and IX. Specifically, measurement of the global tensile properties indicated that the tensile strengths of the EB welds in the transverse and longitudinal directions were on the same order as that of the base metal (BM). Evaluation of the local tensile properties using a digital image correlation (DIC) methodology showed higher local yield strengths in the fusion zone (FZ) and heat-affected zone (HAZ) of 727 MPa and 740 MPa, respectively, relative to the BM value of 663 MPa. Also, the average impact energies for the FZ and HAZ were 63 J and 148 J, respectively, and attributed to the different failure mechanisms in the HAZ (dimples) versus the FZ (quasi-cleavage consisting of facets and dimples). This study shows that the application of PWHT plays an important role in improving the weld quality and performance of EB-welded CA6NM and provides the essential data for validating the design and manufacturing process for next-generation hydroelectric turbine products

Joining of dissimilar alloys Ti-6Al-4V and Ti-6Al-2Sn-4Zr-2Mo-0.1Si using linear friction welding

Dissimilar joints between Ti-6Al-4V (Ti-64) and Ti-6Al-2Sn-4Zr-2Mo-0.1Si (Ti-6242) were manufactured using linear friction welding. The weld quality, in terms of the microstructure and mechanical properties, was investigated after stress relief annealing (SRA) at 750 °C for 2 h and compared with the as-welded (AWed) results. The central weld zone (CWZ) microstructure in the AWed condition consisted of recrystallized prior-β grains with α' martensite, which transformed into an acicular α+β structure after SRA. The hardness in the AWed condition was highest in the CWZ and decreased sharply through the thermomechanically affected zones (TMAZ) to the parent materials (PMs). After SRA, the hardness of the CWZ decreased, mainly due to tempering of the α' martensite microstructure. Static tensile testing of the dissimilar welds in both the AWed and stress relief annealed (SRAed) conditions resulted in ductile fracture occurring exclusively in the Ti-6Al-4V side of the joint. The promising results on joining of Ti-64 to Ti-6242 provide valuable insight for tailoring performance of next-generation aero-engine products

Traumatic injuries in pregnant women: a case of motor vehicle accident for “Ground Round” discussion

The main objective for introducing this case study is to create a platform from which the importance of road traffic related injuries and traumas can be emphasized and discussed within and across various fields of investigation. The long term goal is to entice public campaign around unmet needs for higher road safety measures to reduce primary, secondary, and tertiary risks of injuries and traumas

Determination of CagA EPIYA motif in Helicobacter pylori strains isolated from patients with digestive disorder

This study was conducted to identify patterns of cagA EPIYA motifs in H. pylori strains isolated from patients with gastrointestinal diseases in Hospitals of Shahrekord, and investigate the association between these biomarkers and clinical outcomes of gastrointestinal diseases due to H. pylori. In this study, 253 patients with gastrointestinal diseases were studied within 1395-1396. Histopathological investigations and urease test showed that 207 isolates were H. pylori-positive. Then, screening using a molecular technique, PCR, confirmed that 159 isolates had cagA. Finally, the pattern and prevalence of the motifs were determined by PCR and identified a number of motifs were sequenced. Results of this study showed that the pattern of motifs was as follows: ABC (140 isolates) (93/7%), ABCC (6 isolates) (3/77%), ABCCC (4 isolates) (2/5%), AB (7 isolates) (4/4%), AC (1 isolate) (0/6%), and BC (1 isolate) (0/6%). Sequencing results showed the presence of changed EPIYA motif in some isolates. CM motif sequence was also seen in all isolates. In this study, no significant association was seen between the prevalence rate of different patterns and clinical symptoms (p = 0.71). There is a slight association between the presence of ABC motifs and the type of digestive disorder (p = 0.056). Results indicated that ABC was the most frequently seen pattern however, in such that positive cases of ABC motifs were more common in gastritis. All isolates had kinase phosphorylation region, and the observed pattern in this region was a generally western type (ABC). Keywords:Microbiology; Immunology; Genetics; Molecular biology; Cancer research; Diet; Public health; Gastrointestinal system; Infectious disease; Helicobacter pylori; CagA motif; EPIYA; Gastric cance

Fatigue Behavior of Linear Friction Welded Ti-6Al-4V and Ti-6Al-2Sn-4Zr-2Mo-0.1Si Dissimilar Welds

The use of joints fabricated from dissimilar titanium alloys allows the design of structures with local properties tailored to different service requirements. To develop welded structures for aerospace applications, particularly under critical loading, an understanding of the fatigue behavior is crucial, but remains limited, especially for solid-state technologies such as linear friction welding (LFW). This paper presents the fatigue behavior of dissimilar titanium alloys, Ti–6Al–4V (Ti64) and Ti–6Al–2Sn–4Zr–2Mo–0.1Si (Ti6242), joined by LFW with the aim of characterizing the stress versus number of cycles to failure (S-N) curves in both the low- and high-cycle fatigue regimes. Prior to fatigue testing, metallurgical characterization of the dissimilar alloy welds indicated softening in the heat-affected zone due to the retention of metastable β, and the typical practice of stress relief annealing (SRA) for alleviating the residual stresses was effective also in transforming the metastable β to equilibrated levels of α + β phases and recovering the hardness. Thus, the dissimilar alloy joints were fatigue-tested in the SRA (750 °C for 2 h) condition and their low- and high-cycle fatigue behaviors were compared to those of the Ti64 and Ti6242 base metals (BMs). The low-cycle fatigue (LCF) behavior of the dissimilar Ti6242–Ti64 linear friction welds was characterized by relatively high maximum stress values (~ 900 to 1100 MPa) and, in the high-cycle fatigue (HCF) regime, the fatigue limit of 450 MPa at 107 cycles was just slightly higher than that of the Ti6242 BM (434 MPa) and the Ti64 BM (445 MPa). Fatigue failure of the dissimilar titanium alloy welds in the low-cycle and high-cycle regimes occurred, respectively, on the Ti64 and Ti6242 sides, roughly 3 ± 1 mm away from the weld center, and the transitioning was reasoned based on the microstructural characteristics of the BMs

Microstructure, Tensile Properties, and Fatigue Behavior of Linear Friction-Welded Ti-6Al-2Sn-4Zr-2Mo-0.1Si

This paper presents the microstructural characteristics and mechanical properties of linear friction-welded (LFWed) Ti-6Al-2Sn-4Zr-2Mo-0.1Si (Ti-6242) in as-welded (AWed) and stress relief-annealed (SRAed) conditions. The weld center (WC) of the AWed Ti-6242 consisted of recrystallized prior-&beta; grains with &alpha;&rsquo; martensite that were tempered during SRA at 800 &deg;C for 2 h and transformed into an acicular &alpha; + &beta; microstructure. The peak hardness values, obtained in the AWed joints at the WC, sharply decreased through the thermomechanically affected zones (TMAZs) to the heat-affected zone (HAZ) of the Ti-6242 parent metal (PM). The SRA lowered the peak hardness values at the WC slightly and fully recovered the observed softening in the HAZ. The tensile mechanical properties of the welds in the AWed and SRAed conditions surpassed the minimum requirements in the AMS specifications for the Ti-6242 alloy. Fatigue tests, performed on the SRAed welds, indicated a fatigue limit of 468 MPa at 107 cycles, just slightly higher than that of the Ti-6242 PM (434 MPa). During tensile and fatigue testing, the welds failed in the PM region, which confirms the high mechanical integrity of the joints. Both the tensile and fatigue fracture surfaces exhibited characteristic features of ductile Ti-6242 PM