Fe nano-particle coatings for high temperature wear resistance

Oxidational wear continues to present an economic challenge for the replacement of components subject to high temperature fretting and sliding contacts in applications such as gas turbine engines. At elevated temperatures, low friction oxide ‘glaze’ layers can form and act as an interface between the contact and the substrate material. Whilst desirable, the glaze is formed from wear debris and often consumes the underlying substrate material. In order to induce rapid formation of low friction oxide layers without a severe ‘running-in’ period, nano particles of Fe in the range 5-10nm were deposited on ground flat ended pin and plate 080M40 substrates using a terminated gas condensation PVD process, to a thickness of 600nm. Coatings were tested in a reciprocating geometry at a fixed stroke length of 0.4mm, frequency of 31Hz and 40N normal load (1MPa contact stress) and at ambient, 300°C and 540°C. At ambient temperature the coated surfaces exhibited higher friction but lower wear compared to the uncoated substrates, whereas at elevated temperatures, the coated surfaces exhibited slightly lower steady state dynamic friction coefficients, and minimal changes in wear depth after a short incubation period. SEM of the worn surfaces indicated that hard oxide plateaus were responsible for the load bearing contact area at elevated temperatures. Cross sectional FIB, TEM and SIMS confirmed that at elevated temperatures, the nano-particle coating induced rapid formation of a nano-crystalline porous surface oxide film of mixed composition which protected the substrate from severe wear during the running-in period

Factors predicting success of vaginal delivery in women with oligohydramnios undergoing induction of labour

Background: Aim was to study the predicting factors for success of vaginal delivery, in women with oligohydramnios undergoing induction of labour.Methods: An observational study conducted in tertiary care centre Kamineni Hospital in 100 patients in 1-year duration with vaginal misoprostol tablets to predict the success of vaginal delivery in cases, if oligohydramnios undergoing induction of labor.Results: In our study total 100 cases was induced. Among these 81% had successful normal vaginal delivery and 19% had caesarean section delivery. Those who underwent caesarean section, their NST had become non reassuring at any time in labour, provided all supportive measures but their labour was terminated by caesarean section for sake of mother or baby.Conclusions: It is preferable to induce the patients of oligohydramnios at term with continous fetal heart rate monitoring and also variability of the fetal heart rate pattern with uterine contractions.

A study of correlation of antenatal uterine scar thickness by transabdominal ultrasound with intraoperative lower uterine segment scar grading in elective repeat cesarean delivery

Background: Caesarean section (CS) is the most common obstetric surgery performed world-wide. The objective of this study was to correlate the antenatal sonographic lower uterine segment (LUS) scar thickness in women with previous one cesarean section with intra operative LUS scar grading.Methods: A Prospective observational study was conducted from December 2014 to November 2015. In a tertiary care center. 200 pregnant women from ANC clinic with previous one LSCS were recruited. Transabdominal USG done between 36-38 weeks. LUS thickness was measured from bladder wall-myometrium interphase and myometrium-chorioamniotic membrane inter phase. Intraoperative grading of LUS scar was done. Based on grading of scar participants were assigned into scar dehiscence group (grade III and IV LUS scar) and non-dehiscence group (Grade I and II LUS scar).Results: Mean LUS thickness was 3.41±0.623 mm (range: 2-7 mm). Mean LUS thickness in the scar dehiscence group and non-dehiscence group was 2.98±0.55 mm and 3.48±0.60 mm (P value 3.5 mm, can be counselled regarding TOLAC if not contraindicated

Understanding BGP Session Failures in a Large ISP

Abstract—The current global Internet routing frequently suffers from cascading routing changes and slow routing convergence. Such instability can significantly affect the performance of real-time Internet applications such as VoIP, multimedia conferencing and online gaming. One major cause of routing instability is the failure of BGP peering sessions, but there has been little understanding of the factors that contribute to the failures of operational BGP sessions. In this paper, we present a systematic study on the failures of a few hundred BGP sessions using data collected in a tier-1 ISP network over a 9-month period. We first quantify the impact of the session failures on both the control plane and the data plane. We then use syslog events to identify the direct triggers of session failures. Furthermore, we use several heuristics, including link failure information, session down time and traffic level, to identify the root problems that led to these session failures. We found that the major root causes are administrative session resets and link failures, each contributing to 46.1 % and 30.4 % of the observed session failures. I

Understanding BGP Session Failures in a Large ISP

The current global Internet routing frequently suffers from cascading routing changes and slow routing convergence. Such instability can significantly affect the performance of real-time Internet applications such as VoIP, multimedia conferencing and online gaming. One major cause of routing instability is the failure of BGP peering sessions, but there has been little understanding of the factors that contribute to the failures of operational BGP sessions. In this paper, we present a systematic study on the failures of a few hundred BGP sessions using data collected in a tier-1 ISP network over a 9-month period. We first quantify the impact of the session failures on both the control plane and the data plane. We then use syslog events to identify the direct triggers of session failures. Furthermore, we use several heuristics, including link failure information, session down time and traffic level, to identify the root problems that led to these session failures. We found that the major root causes are administrative session resets and link failures, each contributing to 46.1% and 30.4% of the observed session failures. © 2007 IEEE

Magnetic domains and annealing-induced magnetic anisotropy in nanocrystalline soft magnetic materials

The magnetic domains of nanocrystalline Fe84Nb6B10 annealed under static and rotating magnetic fields have been investigated by means of magneto-optical Kerr effect (MOKE) microscopy in order to clarify the origin of the dramatic magnetic softening brought about by rotating field annealing. The coercivity (Hc) values after static- and rotating-magnetic field annealings are 5.9 and 3.0  A/m, respectively. The MOKE image after static field annealing implies a highly coherent uniaxial anisotropy (Ku) in the sample whereas no sign of such a strong Ku is evident in the domain configuration after rotating field annealing. Our analytical solution of the random anisotropy model with additional Ku predicts that the fluctuating amplitude of the effective anisotropy (δK) in nanocrystalline Fe84Nb6B10 decreases from 20 to 11 J/m3 by removing Ku. The observed reduction of Hc may be attributed to this decrease in δK induced by rotating field annealing

Multi-Biometric System Using Fuzzy Vault

Advancement of electronic media not only improved our living standard, but created several amenities that makes work bit easier. On the other hand, media faces several challenges. Biometric systems are promising technology with accurate data and secure features. However, many existing Biometric systems based on a single authentication process have higher vulnerability than a Multi-biometric systems. Multi-biometric systems accumulate evidence from more than one biometric trait in order to recognize a person. They provide higher recognition accuracy and larger population coverage. Multi-biometric systems store multiple biometric templates for each user, which results in increased risk to user privacy and system security. To secure the individual biometric template by using the fusion method to store the data. The fuzzy vault is proposed. By the end of this paper we would like to propose an idea to further improve the data security and also make this process take the less time

Characteristic magnetic length-scales in Vitroperm—Combining Kerr microscopy and small-angle neutron scattering

We present a study of the magnetic-field dependence of the magnetic microstructure of the nanocrystalline soft magnet Vitroperm (Fe73Si16B7Nb3Cu1), which was treated so as to exhibit a macroscopic magnetic anisotropy. The samples were analysed using Kerr microscopy and small-angle neutron scattering (SANS). As the applied magnetic field is decreased starting from saturation, we find that two processes occur independently: the formation of a domain structure with the net magnetisation of the domains aligned along the macroscopic easy axis and the increase in magnitude of static, nanometer-scale fluctuations of the spin orientation. The domain structure observations from Kerr microscopy are in excellent agreement with the results of the SANS experiments

Effect of large mechanical stress on the magnetic properties of embedded Fe nanoparticles

Magnetic nanoparticles are promising candidates for next generation high density magnetic data storage devices. Data storage requires precise control of the magnetic properties of materials, in which the magnetic anisotropy plays a dominant role. Since the total magneto-crystalline anisotropy energy scales with the particle volume, the storage density in media composed of individual nanoparticles is limited by the onset of superparamagnetism. One solution to overcome this limitation is the use of materials with extremely large magneto-crystalline anisotropy. In this article, we follow an alternative approach by using magneto-elastic interactions to tailor the total effective magnetic anisotropy of the nanoparticles. By applying large biaxial stress to nanoparticles embedded in a non-magnetic film, it is demonstrated that a significant modification of the magnetic properties can be achieved. The stress is applied to the nanoparticles through expansion of the substrate during hydrogen loading. Experimental evidence for stress induced magnetic effects is presented based on temperature-dependent magnetization curves of superparamagnetic Fe particles. The results show the potential of the approach for adjusting the magnetic properties of nanoparticles, which is essential for application in future data storage media