Fabrication and Characterization of Shape Memory Alloy (SMA) - Max Phase Bilayers and Composites

With the rapid growth of the transportation industry (automotive and aerospace), the demands for the control of noise and enhancing the stability of structures, through the development of high damping materials are continually increasing. In the last two decades, increasing attention is being given to develop high damping materials for various applications. The aim of this study is to develop high damping material by combining these two unique material systems, a NiTi (SMA) with a Ti3SiC2 (MAX phase) which are individually excellent materials for damping applications. Another goal here is to investigate whether large recoverable shape change in SMAs during thermo-mechanical cycling can generate residual stresses and defects that could further enhance damping capability of the novel SMA-MAX phase composites. In this study, NiTi-Ti3SiC2 composites are processed using spark plasma sintering (SPS) technique and microstructurally characterized using scanning electron microscopy (SEM) to study the distribution of NiTi, Ti3SiC2 and remnant porosity in the composite. The highest energy dissipation is observed for the thermo-mechanically cycled (TC) composite followed by the as-sintered (AS) composite, pure NiTi and pure Ti3SiC2 when compared at the same applied stress levels. Both the AS and TC composites exhibited higher damping up to 200 MPa stress than any of the metal – MAX phase composites reported in the literature to date. Interfaces play a crucial role in determining the overall properties and performance of the composites. Bulk components of NiTi (SMA) and Ti3SiC2 (MAX phase) are successfully joined using pressure assisted diffusion bonding. Interfaces thus formed are micro-structurally characterized where the interfacial structure consists of NiTi / Ti2Ni / Ti5Si3 / NiTiSi / Ti3SiC2. Nano-indentation showed that the elastic moduli of the phases in the interface are close to that of Ti3SiC2 while their hardness is higher than that of both Ti3SiC2 and NiTi. Four-point bend delamination tests are used to study the fracture behavior of the NiTi-Ti3SiC2 interface under mixed mode loading configuration for bilayer specimens. NiTi starts to deform plastically in the region between the inner loading points prior to crack propagation suggesting the formation of strong, tough interface. This is contrary to most literature studies wherein crack propagation occurs prior to onset of plastic deformation in the metallic phase, because of the weak interface. Thus, this study demonstrates the interplay between the interfacial and yield strength of the metallic phase in determining interfacial fracture behavior. Fracture occurs along the interface between Ti3SiC2 and NiTiSi phase, occasionally inside the Ti3SiC2 phase and also in the different phases in the reaction layer. Formation of strong interface enables efficient load transfer between SMA and MAX phase leading to the observation of excellent damping in composites. In conclusion, this study demonstrates the potential of novel SMA-MAX phase composites for high damping applications

Role of slow decompression, injection carbetocin and Samarth Ram cannula for preventing postpartum haemorrhage in a patient of acute severe polyhydramnios

We presented a case of a 30-year-old woman G3P1L1A1 who was diagnosed with severe polyhydramnios at 29 weeks of gestation. The patient was managed conservatively with amnioreduction. However, after one week of conservative management showed a further increase in the AFI (54-55 cm) with severe breathlessness and abdominal pain. A decision to terminate pregnancy was taken in view of failed conservative management. Emergency LSCS done under general anaesthesia. Amniotomy was done by slow uterine decompression. Simultaneously injection carbetocin 100 mcg IV bolus over 1 minute given. Postpartum haemorrhage was prevented by using Samarth Ram cannula. Further recovery was uneventful and patient discharged on day 3 of surgery

Asymptomatic bacteriuria in pregnancy screening, risk factors, diagnosis and treatment

Background: Asymptomatic bacteriuria is a frequent pregnancy issue that, if left untreated, increases the risk of premature birth and pyelonephritis. Urine culture is the basis for the diagnosis. In the current study, 200 pregnant women are examined for severe asymptomatic bacteriuria to gain insight into its frequency in emerging nations, to re-evaluate some predisposing factors, and to test for the susceptibility of specific aetiological agents. The purpose of this study was to assess the prevalence of asymptomatic bacteriuria in pregnant women as well as to isolate, characterise, and establish the pathogens antibiotic susceptibility patterns. Methods: 200 pregnant women with asymptomatic bacteriuria are included in the study. By using traditional techniques, isolates were located, and their antibiotic susceptibility patterns were established. Results: Significant bacteriuria was detected in 102 individuals (51%) in total. The three most efficient antibiotics against the urine isolates were determined to be Piperacillin-Tazobactam, Amikacin, and Nitrofurantion. Escherichia coli was the most prevalent bacterium, followed by Klebsiella pneumoniae. Conclusions: In the group under study, prenatal patients frequently have asymptomatic bacteriuria. All prenatal patients should have routine urine cultural testing to detect any undetected infections. This action will significantly lessen pregnancy-related maternal and obstetric problems

A REVIEW ON ATMOSPHERIC PARAMETER MONITORING SYSTEM FOR SMART CITIES USING INTERNET

Objects of everyday life will be equipped with microcontroller, microprocessor, embedded system and transceivers for digital communication with one another and with the users, becoming an integral part of internet. In this paper, we focus specifically to an urban internet for atmospheric parameter system. Through the mechanism of internet, we make a modem specially focused on atmospheric parameter which consists of three sensors for air, noise pollution and temperature measurement and the controlling of street light thus connected to the embedded system. This transmitted the data to the server and received by the pc or GUI modem. For this, modem is designed to support SMART CITY vision, which aims at exploiting the most advanced communication technologies to support added-value services for the administration of the city and for the citizens

Interfacial study of NiTi-Ti3SiC2 solid state diffusion bonded joints

The interfaces between the stress-assisted diffusion bonded Ti3SiC2 and equiatomic NiTi, two distinct material systems that show pseudoelasticity were studied. The interfaces were formed in the 800-1000 degrees C temperature range, for 1, 5 and 10 h under flowing argon. Bonding was observed in all the cases considered, except at 800 degrees C after 1 h. Morphology and reaction phases in the interface were characterized using scanning electron microscopy, elemental micro probe analysis and electron back-scatter diffraction analysis. The interfacial structure formed between NiTi and Ti3SiC2 layers consists of NiTi/Ti2Ni/Ti5Si3/NiTiSi/Ti3SiC2. Diffusion of Si into NiTi from Ti3SiC2, and Ni from NiTi into reaction zone was found to be responsible for the formation of reaction layers in the interface and thus for bonding at these conditions. The overall reaction layer thickness grows following the parabolic kinetic law. Nano-indentation and Vickers micro hardness tests were carried out to investigate the mechanical properties of the interface. Nano-indentation showed that the elastic moduli of the phases in the interface are close to that of Ti3SiC2 while their hardness is higher than that of both Ti3SiC2 and NiTi. Artificially formed cracks through microindents were observed to be branched and propagated into Ti3SiC2 phase indicating good resistance against delamination. (C) 2014 Elsevier B.V. All rights reserved.The interfaces between the stress-assisted diffusion bonded Ti3SiC2&nbsp;and equiatomic NiTi, two distinct material systems that show&nbsp;pseudoelasticity&nbsp;were studied. The interfaces were formed in the 800&ndash;1000&nbsp;&deg;C temperature range, for 1, 5 and 10&nbsp;h under flowing&nbsp;argon. Bonding was observed in all the cases considered, except at 800&nbsp;&deg;C after 1&nbsp;h. Morphology and reaction phases in the interface were characterized using&nbsp;scanning electron microscopy, elemental micro probe analysis and&nbsp;electron backscatter diffraction&nbsp;analysis. The interfacial structure formed between NiTi and Ti3SiC2&nbsp;layers consists of NiTi/Ti2Ni/Ti5Si3/NiTiSi/Ti3SiC2. Diffusion of Si into NiTi from Ti3SiC2, and Ni from NiTi into reaction zone was found to be responsible for the formation of reaction layers in the interface and thus for bonding at these conditions. The overall reaction layer thickness grows following the parabolic kinetic law.&nbsp;Nano-indentation&nbsp;and Vickers&nbsp;micro hardness&nbsp;tests were carried out to investigate the mechanical properties of the interface. Nano-indentation showed that the&nbsp;elastic moduli&nbsp;of the phases in the interface are close to that of Ti3SiC2while their hardness is higher than that of both Ti3SiC2&nbsp;and NiTi. Artificially formed cracks through microindents were observed to be branched and propagated into Ti3SiC2&nbsp;phase indicating good resistance against&nbsp;delamination.</p

Automatic prediction of intelligible speaking rate for individuals with ALS from speech acoustic and articulatory samples

: Purpose: This research aimed to automatically predict intelligible speaking rate for individuals with Amyotrophic Lateral Sclerosis (ALS) based on speech acoustic and articulatory samples. Method: Twelve participants with ALS and two normal subjects produced a total of 1831 phrases. NDI Wave system was used to collect tongue and lip movement and acoustic data synchronously. A machine learning algorithm (i.e. support vector machine) was used to predict intelligible speaking rate (speech intelligibility × speaking rate) from acoustic and articulatory features of the recorded samples. Result: Acoustic, lip movement, and tongue movement information separately, yielded a R2 of 0.652, 0.660, and 0.678 and a Root Mean Squared Error (RMSE) of 41.096, 41.166, and 39.855 words per minute (WPM) between the predicted and actual values, respectively. Combining acoustic, lip and tongue information we obtained the highest R2 (0.712) and the lowest RMSE (37.562 WPM). Conclusion: The results revealed that our proposed analyses predicted the intelligible speaking rate of the participant with reasonably high accuracy by extracting the acoustic and/or articulatory features from one short speech sample. With further development, the analyses may be well-suited for clinical applications that require automatic speech severity prediction