Investigating the Effect of Fluid Flow on Chatter Vibration in Drilling

In this work the effect of fluid flow on damping characteristics in deep drilling is investigated. Chatter suppression could be performed by both active and passive methods. Generally, passive methods are less costly; however, they require modifications in tool and machine design and structure before the operation; hence, they may not be suitable for currently running equipment. On the other hand, inducting fluid flow as a damping tool does not require any changes in the machine tool structure and could be applied only by adding an extra part (e.g. a cylinder around the drill bit as a fluid container) to the cutting setup. This container could be a flexible cylinder or a multi sliding part cylinder which surrounds the drill bit and the damping fluid and helps to suppress the chatter vibration. In this study, it was shown that conventional cutting fluids could be used as the damping agents; in fact, they could drastically improve damping characteristics of the cutting process. It was also shown that the gap between the drill bit and the cylinder does not have to be precise which lead to even cheaper construction costs. In other words, the asymptotic border of stability (ABL) would drastically rise by adding a cylinder with one to two millimeter gap around the drill bit and forcing the cutting fluid to pass through this gap

Urinary tract infection among intellectual disability individuals ?Etiology and antibiotic resistance patterns? in rehabilitation centers of Mazandaran province, Northern Iran

Objective. Urinary tract infections (UTIs) are amongst the most common infections and account for large proportion of antibacte- rial drug consumption. The aim of this study was to determine the rate and the etiologic agents of UTIs in inhabitants of rehabili- tation centers of Mazandaran province in northern Iran and to evaluate the antimicrobial susceptibility patterns of the uropatho- gens isolated. Methods. Clean catch midstream urine sample was collected from each of 314 participants (163 males, 151 females) residing in 12 rehabilitation centers of Ramsar, Nowshahr, Chalous, Amol, Sari and Behshahr. Urine specimens were cultured and bacterial iso- lates were identified by conventional methods. All urines fulfilling the criteria for the presence of significant bacteriuria (?104 cfu / ml urine) were defined as positive. Antibiotic susceptibility testing was performed by Kirby-Bauer disc diffusion method. Results. The rate of urinary tract infection was 30.9% with the highest rate in pediatrics (p inf. 0.0001).The prevalence of UTIs were shown to be higher in females than in males with the rate of 46.3% in young aged females (20-29 years), 60% in middle aged group (40-49 years) and 50% in elderly (> 50 years). Bacteria most frequently isolated from urine specimens was Escherichia coli (39.2%) with the highest rate of infection in females age group inf. 10 years (p inf. 0.001). Among the antibiotics tested against the isolated organisms for susceptibility test, ceftriaxone and gentamicin main- tain good activity against the majority of gram negative bacteria that cause UTIs recovered from individuals with intellectual dis- ability. Vancomycin was effective against Staphylococcus aureus. Conclusions. This survey shows that the prevalence of UTIs among inhabitants of institutions for mentally retarded persons in Mazandaran province of Iran is much higher than normal population

Enhanced superconducting proximity effect in clean ferromagnetic domain structures

We investigate the superconducting proximity effect in a clean magnetic structure consisting of two ferromagnetic layered domains with antiparallel magnetizations in contact with a superconductor. Within the quasiclassical Green's function approach we find that the penetration of the superconducting correlations into the magnetic domains can be enhanced as compared to the corresponding single domain structure. This enhancement depends on an effective exchange field which is determined by the thicknesses and the exchange fields of the two domains. The pair amplitude function oscillates spatially inside each domain with a period inversely proportional to the local exchange field. While the oscillations have a decreasing amplitude with distance inside the domain which is attached to the superconductor, they are enhancing in the other domain and can reach the corresponding normal metal value for a zero effective exchange field. We also find that the corresponding oscillations in the Fermi level proximity density of states as a function of the second domain's thickness has an growing amplitude over a range which depends on the effective exchange field. Our findings can be explained as the result of cancellation of the exchange fields induced phases gained by an electron inside the two domains with antiparallel magnetizations.Comment: 7 pages, 4 figure

Brillouin Lasing with a CaF_2 Whispering Gallery Mode Resonator

Stimulated Brillouin scattering with both pump and Stokes beams in resonance with whispering gallery modes of an ultra high Q CaF_2 resonator is demonstrated for the first time. The resonator is pumped with 1064 nm light and has a Brillouin lasing threshold of 3.5 microwatt. Potential applications include optical generation of microwaves and sensitive gyros

Collection, evaluation and classification of Iranian confectionary sunflower (Helianthus annuus L.) populations using multivaraite statistical techniques

Characterization of confectionary sunflower germplasm resources is critical to their efficient collection and management as well as for breeding programs. Thirty six (36) confectionary sunflower populations originating from different regions of Northwest Iran were characterized using 15 agro-morphological traits. Among the studied traits, high coefficients of variation were observed for harvest index (48.36), seed yield (42.07) and petiole length (41.63). Cluster analysis using Ward's method classified the 36 populations into four groups. A large number of genotypes was placed in cluster III (16 genotypes) followed by cluster I (13), cluster IV (4) and cluster II (3). Clusters I, III and VI include genotypes from different sources indicating no association between clustering pattern and eco-geographical distribution of genotypes. The maximum inter-cluster distance of 9.03 was observed between clusters II and VI indicating the possibility of high heterosis if individuals from these two clusters are cross-bred. Principal component analysis resulted in the first four components with Eigen value greater than one accounting for 78% of the total variation. The results of PCA were closely in line with those of cluster analysis. These results can now be used by breeders to develop high yielding sunflower hybrids.Key words: Cluster analysis, confectionary sunflower, genetic variability, principal component analysis

Application of Deep Neural Network to Predict the High-Cycle Fatigue Life of AISI 1045 Steel Coated by Industrial Coatings

In this study, deep learning approach was utilized for fatigue behavior prediction, analysis, and optimization of the coated AISI 1045 mild carbon steel with galvanization, hardened chromium, and nickel materials with different thicknesses of 13 and 19 mu m were used for coatings and afterward fatigue behavior of related specimens were achieved via rotating bending fatigue test. Experimental results revealed fatigue life improvement up to 60% after applying galvanization coat on untreated material. Obtained experimental data were used for developing a Deep Neural Network (DNN) modelling and accuracy of more than 99%.was achieved. Predicted results have a fine agreement with experiments. In addition, parametric analysis was carried out for optimization which indicated that coating thickness of 10-15 mu m had the highest effects on fatigue life improvement

An Analytical Study of the Effect of Fluid Flow on Damping Characteristics in Deep Drilling

In this study a new method for suppression of chatter vibration in deep drilling based on the model previously provided by authors [Mehrabadi et al., International Journal of Machine Tools and Manufacture 49.12 (2009): 939-946] is discussed. The study showed that the application of the fluid flow would improve the damping characteristic of the drill bit. Some of the advantages of this method are: (i) being simple and low cost in construction, (ii) easy to assemble, and (iii) elimination of the need to adjust damping characteristic of the suppression method. In this research investigation, it is shown that by introducing a Stokes flow around the drill bit contained in a jacket, asymptotic border line of stability could be raised drastically while frequency of the chatter does not vary dramatically

Molecular characterization and similarity relationships among sunflower (Helianthus annuus L.) inbred lines using some mapped simple sequence repeats

Information about the genetic diversity and relationships among breeding lines and varieties is not only useful for germplasm conservation and inbred line identification, but also for the selection of parental lines for quantitative trait loci (QTL) mapping as well as hybrid breeding in crops, including sunflower. In order to develop mapping populations, genetic distances among twenty eight sunflower genotypes were evaluated using simple sequence repeat (SSR) markers. One hundred and two markers were generated by 38 SSR loci and the mean for the number of allele per locus was 2.32. Polymorphism information content (PIC) values ranged from 0.09 (locus ha3555) to 0.62 (locus ORS598) with an average of 0.41. Jaccard's coefficient similarity matrix for the studied sunflower  genotypes varied from 0.25 to 0.9 indicating a broad genetic base. The maximum similarity (0.9) was observed between genotypes RT931 and ENSAT-R5, while the lowest similarity (0.25) was between genotypes LC1064C and LR64. Based on unweighted pair group method with arithmetic mean (UPGMA) clustering algorithm, the studied genotypes were clustered in four groups. However, some genotypes have the same specific characters that influence their clustering, and as a result, the results of the principal coordinate analysis (PCoA) largely corresponded to those obtained through cluster analysis.Key words: Cluster analysis, genetic diversity, principal coordinate analysis, sunflower, simple sequence repeat

Comparison of quadruple and triple Furazolidone containing regimens on eradication of helicobacter pylori

Background: The effectiveness of classic standard triple therapy regimen of helicobacter pylori (H. pylori) eradication has decreased to unacceptably low levels, largely related to development of resistance to metronidazole and clarithromycin. Thus successful eradication of H. pylori infections remains challenging. Therefore alternative treatments with superior effectiveness and safety should be designed and appropriately tested in all areas depending on the native resistance patterns. Furazolidone has been used successfully in eradication regimens previously and regimens containing furazolidone may be an ideal regimen. Methods: H. pylori infected patients with proven gastric or duodenal ulcers and /or gastric or duodenal erosions at Imam Khomeini Hospital in Sari/Northern Iran, were randomly allocated into three groups: group A (OABF) with furazolidone (F) (200 mg bid.), group B (OABM-F) metronidazole (M) (500 mg bid.) for the first five days, followed by furazolidone (F) (200 mg bid.) for the second five days and group C (OAF) with furazolidone (F) (200 mg tid.). Omeprazole (O) (20 mg bid.) and amoxicillin (A) (1000 mg bid.) were given in all groups; bismuth (B) (240 mg bid.) was prescribed in groups A&B. Duration of all eradication regimens were ten days. Eight weeks after treatment, a 14C-urea breath test was performed for evaluation of H. pylori eradication. Results: A total of 372 patients were enrolled in three groups randomly (124 patients in each group); 120 (97) patients in group A (OABF), 120 (97) in group B (OABM-F) and 116 (93) in group C (OAF) completed the study. The intention-to-treat eradication rates were 83.7 (95 CI= 77.3-90.4), 79.8 (95 CI= 72.6-87), and 84.6 (95 CI= 78.2-91.1) and per-protocol eradication rates were 86.6 (95 CI= 80.5-92.8), 82.5 (95 CI= 75.6-89.4), and 90.5 (95 CI= 85.1-95.9) for groups OABF, OABM-F, and OAF, respectively. No statistical significant differences were found in case of severe drug adverse effects between the above mentioned three groups (p> 0.05). The most common side effects, namely nausea and fever, occurred in all groups, but more frequently in group C (OAF) (p< 0.05). Conclusion: In developing countries such as Iran, furazolidone-based regimens can substitute clarithromycinbased regimens for H. pylori eradication because of a very low level of resistance, low cost and high effectiveness. Considering per-protocol eradication rate of ten days OAF regimen, and the acceptable limit of ninety percent, we recommend this regimen in developing countries such as Iran to be substituted of classic standard triple therapy. In order to minimize rare serious adverse effects, one week high dose OAF regimen should be taken into consideration in other studies

Short term effects of ginger on quality of life, disease activity index, inflammatory and oxidative stress factors in ulcerative colitis

Background: Chronic inflammation and oxidative stress are the two essential factors determining ulcerative colitis (UC) onset and severity status. In present study, we aimed to investigate short-term effects of ginger (Zingiber officinale) as a well-known antioxidant and anti-inflammatory agent on the quality of life, disease activity index and some of inflammatory and oxidative stress factors in patients with active mild to moderate UC. Methods: This study was a double blind placebo controlled randomized clinical trial conducted in nutrition and diet therapy clinic of Shahid Beheshti University of Medical Science, Tehran, Iran, from October 2017 to June 2018. Forty-six patients with active mild to moderate UC daily consumed four capsules of 500 mg dried ginger powder or similar placebo through eating their meals for 6 weeks. Before and after intervention, we analyzed patient´s scores of disease activity index, by simple clinical colitis activity index questionnaire (SCCAIQ) as well as their quality of life using inflammatory bowel disease questionnaire-9 (IBDQ-9). We also measured serum concentrations of total antioxidant capacity (TAC), malondialdehyde (MDA), tumor necrosis factor (TNF-α), high sensitive (hs)-CRP and nuclear factor κB (NF-κB) in fasted blood samples of each participant. Additionally, anthropometric and dietary intake values of energy, mac-ro/micronutrients and minerals of all of participants were assessed at the same time. Results: While the mean of anthropometric measures and dietary intake values remained unchanged during the study, MDA level decreased in ginger group (P=0.04) compared with placebo group. Additionally, ginger supplementation successfully lowered serum levels of TNF-α and disease activity index after 6 weeks of intervention compared with baseline in ginger consumer group, however the increase of quality of life score was not statistically significant in mentioned group versus baseline values. No significant change in other study outcomes was observed at the end of 6 weeks within and between groups. Conclusion: Our data indicates that two grams per day supplementation with dried ginger powder can reduce oxidative stress level of patients with active mild to moderate UC. © 2019, Tehran University of Medical Sciences. All rights reserved