Investigating dimensional and geometrical accuracy of isothermally forged blades

Compressor blades are one of the well-known products made of titanium alloys. They are usually manufactured by a forging process followed by a sequence of machining processes. Precision forging eliminates a considerable amount of machining; however, due to the close tolerances, the process should be designed in a manner to meet dimensional and geometrical tolerances as well as the desired mechanical and metallurgical properties. In this paper, effects of two main process parameters, the process temperature and strain rate, on the dimensional and geometrical accuracy of the isothermally forged blades are investigated experimentally. The results are analyzed by the response surface method (RSM). In order to justify the results and have a tool for further studies, a coupled thermo-mechanical finite element method model is developed and verified by the experimental results. The results show that the process temperature and pressing speed and their interaction have a meaningful effect on the thickness error; however, the interaction effect of the process temperature and pressing speed on the twist error is not considerable and moreover the bow error of the forged blades is not significant. Finally, the results show that for a given geometry, by selection of appropriate process parameters, a sound workpiece with acceptable dimensional and geometrical aspects can be manufactured without any need for a die shape compensation

Development of a Degradation Model for the Collapse Analysis of Composite Aerospace Structures

For stiffened structures in compression the most critical damage mechanism leading to structural collapse is delamination or adhesive disbonding between the skin and stiffener. This paper presents the development of a numerical approach capable of simulating interlaminar crack growth in composite structures as a representation of this damage mecha-nism. A degradation methodology was proposed using shell layers connected at the nodes by user-defined multiple point constraints (MPCs), and then controlling the properties of these MPCs to simulate the initiation and propagation of delamination and disbonding. A fracture mechanics approach based on the Virtual Crack Closure Technique (VCCT) is used to detect growth at the delamination front. Numerical predictions using the degradation methodology were compared to experimental results for double cantilever beam (DCB) specimens to dem-onstrate the effectiveness of the current approach. Future development will focus on address-ing the apparent conservatism of the VCCT approach, and extending the application of the method to other specimen types and stiffened structures representative of composite fuselage designs. This work is part of the European Commission Project COCOMAT (Improved MA-Terial Exploitation at Safe Design of COmposite Airframe Structures by Accurate Simulation of COllapse), an ongoing four-year project that aims to exploit the large strength reserves of composite aerospace structures through more accurate prediction of collapse

Herpes Simplex virus meningitis in children in South East of Caspian Sea, Iran

Background: Herpes simplex virus (HSV) is a member of Herpesviridae and a leading cause of human viral diseases. Meningitis occurs as a complication of HSV-1 or HSV-2 primary infection. Objectives: We aimed to evaluate HSV meningitis in children in Gorgan province, Iran. Patients and Methods: Forty-five cerebrospinal fluid samples were taken from children referred with meningitis symptoms. Samples with negative bacterial culture results were tested for viral, biochemical and cytological assays. DNA extraction and PCR were performed. Results: HSV-1 detected in 4 (8.8%) samples without any HSV-2 infections. Cases with positive results had fever and CSF pleocytosis. Vomiting, headache and higher count of WBC were observed in 3, 2 and 3 cases respectively. The cerebrospinal fluid (CSF) glucose and protein levels were normal and 3 cases showed positive C-reactive protein (CRP) results. Also erythrocyte sedimentation rate (ESR) was higher than normal in all positive cases. Conclusions: Distribution of HSV types in children with meningitis in our area predominantly was type 1 compared with type 2, which has been reported more in other area. © 2014, Ahvaz Jundishapur University of Medical Sciences; Published by Kowsar Corp

A quantum information theoretic quantity sensitive to the neutrino mass-hierarchy

In this work, we derive a quantum information theoretic quantity similar to the Leggett-Garg inequality, which can be defined in terms of neutrino transition probabilities. For the case of $\nu_\mu \to \nu_e/\bar{\nu}_\mu\to\bar{\nu}_e$ transitions, this quantity is sensitive to CP violating effects as well as the neutrino mass-hierarchy, namely which neutrino mass eigenstate is heavier than the other ones. The violation of the inequality for this quantity shows an interesting dependence on mass-hierarchy. For normal (inverted) mass-hierarchy, it is significant for $\nu_\mu \to \nu_e$ ($\bar{\nu}_\mu \to \bar{\nu}_e$) transitions. This is applied to the two ongoing accelerator experiments T$2$K and NO$\nu$A as well as the future experiment DUNE.Comment: 6 pages, 5 figure

EFFECT OF BIOVET AND PROBIOTIC (BM-TECHNOLOGY) ON MILK PRODUCTION IN LACTATING BUFFALOES

This trial was conducted for a period of 90 days at the Livestock Experiment Station, Bahadurnagar, Okara, Pakistan during September - November, 2002. Eighteen lactating buffaloes were divided into three groups A, B and C, with six animals in each group. Animals of Group A were fed a concentrate ration with 2 ml of Biovet per kg of feed, while those of Group B were fed an experimental ration having probiotic 500 gms in 100 kg of concentrate mixture. The Group C animals served as control group. The average daily milk yield was 7.60, 7.39 and 6.15 litres in groups A, B and C, respectively. The corresponding values for milk fat were 7.60, 7.39 and 6.15 percent. The daily feed intakes for concentrate mixture were 4.36, 4.38 and 4.41 kg, while fodder intakes were 35.28, 35.29 and 37.46 kg in respective groups. The values for feed efficiency per kg were 1.70, 1.75 and 2.14 on dry matter basis, 0.197, 0.203 and 0.251 on crude protein basis, while 1.05, 1.08 and 1.35 on TDN basis in Groups A, B and C, respectively. It was also observed that under same feeding and management conditions, the lactating buffaloes supplemented with Biovet (Group A) produced more milk @ 1.45 litres per day, while Group B buffaloes supplemented with probiotic produced 1.22 litres more milk per day than Group C. There was a significant (P<0.05) difference in milk yield between groups A and C, and B and C, while these differences were not significant for average daily feed intake and feed efficiency on crude protein basis. The Biovet (BM-Technology) has favourable effect on milk yield and feed efficiency due to beneficial micro-organisms (BM) and combined function for increased digestibility of concentrate mixture and fodder in lactating buffaloes

Mutations in pre-core and basal-core promoter regions of hepatitis B virus in chronic HBV patients from Golestan, Iran

Objective(s): It has been reported that the mutation of the pre-core (PC) and basal-core promoter (BCP) may play an important role in the development of HBV-related hepatocellular carcinoma (HCC). In this study the PC and BCP mutations were investigated in chronic HBV patients. Materials and Methods: In this study, 120 chronic HBV patients from Golestan, Northeast of Iran who were not vaccinated against HBV, were recruited from the year 2008 to 2012. HBV-DNA extraction from plasma and PCR were performed and positive PCR products were subjected to automated sequencing. Results: One hundred out of 120 (83.3%) patients were HBeAg negative. Comparison of our nucleotide sequences with reference sequence showed high rate mutation in BCP and PC region (96.66%). Frame shift mutation was found in 78 (65%) of patients in BCP region, among them 8 (6.6%) patients showed mutation in PC region. Conclusion: Our results demonstrated high rate of mutations in BCP and PC regions among HBV chronic patients in Northeast of Iran

Mutations in the S gene region of hepatitis B virus genotype D in Golestan Province-Iran

Mutations of HBsAg especially within the "a" determinant could alter the antigenicity of the protein causing failure of HBsAg neutralization and escaping from the host's immune system, resulting in active viral replication and liver disease. This project aimed to investigate mutation in the S gene region of HBV infected patients in Golestan Province-Iran. HBV-DNA extractions from plasma and PCR of 100 patients were performed. Direct sequencing and alignment of S gene were applied using reference sequence from Gene Bank database. All isolates were belonged to genotype D, subgenotype D1, subtype ayw2. Overall 92 point mutations occurred. Of them, 40 (43.47%) were missense and 52 (56.52%) were silent. Mutations were detected in 95 cases (95%). Five of 40 mutations (12.5%) occurred in "a" determinant and 13 (32.5%), 17 (42.5%), and 2 (5%) were seen in antigenic epitope regions of B cell, CD4⁺ and CTL, respectively. Frame shift mutations were seen in 22 cases (22%). 14% of mutations occurred at Major Hydrophilic Region(MHR) area which P120T/S and R122K/T substitutions were the most frequent ones (4%). Mutation in G145R of the S gene was observed in one case. A large number of MHR mutants are in association with failure of HBsAg detection, vaccine, and immunotherapy escape. This study showed "a" determinant S gene mutations in HBV infected people with HBsAg positivity in Golestan Province-Iran. The rate of mutation in our study was 95%. Collectively, the results of this project exhibited that most of mutations were clustered in CD4⁺ antigenic epitopes. © Springer Science+Business Media, LLC 2012

Anomalous rotational-alignment in N=Z nuclei and residual neutron-proton interaction

Recent experiments have demonstrated that the rotational-alignment for the $N=Z$ nuclei in the mass-80 region is considerably delayed as compared to the neighboring $N \ne Z$ nuclei. We investigate whether this observation can be understood by a known component of nuclear residual interactions. It is shown that the quadrupole-pairing interaction, which explains many of the delays known in rare-earth nuclei, does not produce the substantial delay observed for these $N=Z$ nuclei. However, the residual neutron-proton interaction which is conjectured to be relevant for $N=Z$ nuclei is shown to be quite important in explaining the new experimental data.Comment: 4 pages, 3 figures, final version accepted by Phys. Rev. C as a Rapid Communicatio