Studies on Wear Behavior of Aluminium-Tin Alloy

Aluminium and its alloys offer substantial potential for industrial applications because of special characteristics like lightness, excellent resistance to atmospheric corrosion in marine, urban and industrial settings and their ability to be lend to a huge variety of surface treatments like anodization. Aluminium and Aluminium based alloys are used in the automotive industries, parts operated at severe wear and tear conditions. In the present work, with the objective of studying the wear behavior of Al-Sn alloys, some samples of Al and 1% Sn composition alloy were taken. The sliding wear behavior using ball on plate wear tester was observed. Erosion wear behavior, under the influence of different parameters like velocity and angle of incidence of silica particles, sand flux rate etc. was observed. Microstructural characterization, X- ray diffraction studies and surface properties after sliding wear test were also observed. In order to increase the life and performance of Aluminium alloys in various industrial sectors, tribological characterization is critical since failure from wear can be detrimental. Due to the significance associated with tribology, this particular alloy has been studied for tribological properties. Variation of cumulative mass loss for different impingement angles were plotted and analyzed. The individual effects of control parameters was also observed. According to Taguchi analysis, of all the parameters affecting wear rate, “velocity” is the most significant parameter and angle of impingement plays a crucial role too. Corrosion behavior of Aluminium samples was also observed by immersing the Aluminium alloy samples in a sea water bath. Weight was taken after frequent intervals and thus material loss was determined from weight loss

INFLUENCE OF MICRO-SEGREGATION IN PB-S-ALLOYED FREE MACHINING STEELS ON THE SURFACE QUALITY OF THE ROLLED WIRE-ROD

Free machining steel billets were manufactured at the continuous casting machine. The manufactured billets did not exhibit any kind of surface defects but surface cracks and slivers appeared when the billets were rolled into wires and rods at the wire-rod mill. The defects on rolled wire-rod have been detected by a hot eddy current system. Further investigations in these defects with the help of microprobe analysis system and scanning electron microscope equipped with image analysis system revealed micro-segregation of the elements manganese, sulphur and phosphorous in the interdendritic zones

Recycling of tungsten based heavy alloy scrap

The recovery of tungsten from heavy alloy scrap has been explored oxidation of tungsten heavy alloy using oxygen and its subsequent reduction with hydrogen was studied. The oxidation behaviour of the scrap was investigated by simultaneous TG/DTA. Oxidation studies showed a weight gain of 26% and the enthalpy of oxidation was found to be -625 kJ/mol of tungsten. The X-ray diffraction of the oxidised powder has shown the formation of WO3, Fe2WO6 and NiWO4 phases. The reduction of the oxidized material in hydrogen atmosphere at 1000 C yielded a pure tungsten phase in powder form with an approximate weight loss of 25%

Encapsulation of hemoglobin in a bicontinuous cubic phase lipid

AbstractThe effects of encapsulating bovine hemoglobin (BHb) in the bicontinuous cubic phase formed by monooleoylglycerol and water was investigated with Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction. Cubic phase was formed in the presence of 1–10 wt% BHb. Studies using X-ray diffraction reveal that at 0.5–2.5 wt% BHb, the cubic phase structure is characterized by the double diamond lattice (Pn3m). At 2.5–5 wt% BHb, coexistence of two cubic phase structures, Pn3m and the gyroid lattice (la3d), was observed while at BHb concentrations higher than 5 wt% the gyroid structure persists. FTIR shows there is an increase in intensity of the free νC = O (1745 cm−1) and a corresponding decrease in the intensity of the hydrogen bonded νC = O (1720 cm−1) cs the BHb concentration is increased. The νC-O-CO peak shifts from 1183 cm−1 to 1181 cm−1 as the concentration of BHb is raised from 2.5 to 10 wt% indicating BHb may induce subtle changes in the interfacial region of cubic phase monoolein. The bandwidth of the νasCH2 stretch (2926 cm−1) increased in the presence of 5 wt% BHb compared to samples with 2.5 or 10 wt% BHb. The increase in frequency of the νsCH2 stretch (2854 cm−1) induced by increasing temperature 20 to 60°C was dampened when BHb was present compared to samples heated in isotonic buffer. Analysis of the amide I band at 1650 cm−1 showed that the secondary structure of BHb is not affected by encapsulation in monoolein. In vitro release studies showed that 45% of the entrapped BHb was released after 144 h at 37°C. The porous nature of bulk cubic phase was further demonstrated by diffusion of K2Fe(CN)6 and conversion of 73% of the oxyhemoglobin to methemoglobin after 1 h. These results suggest that the cubic phase may be useful for encapsulation of Hb as a red cell substitute and for the encapsulation and delivery of other bioactive agents

Discrete Audio Representation as an Alternative to Mel-Spectrograms for Speaker and Speech Recognition

Discrete audio representation, aka audio tokenization, has seen renewed interest driven by its potential to facilitate the application of text language modeling approaches in audio domain. To this end, various compression and representation-learning based tokenization schemes have been proposed. However, there is limited investigation into the performance of compression-based audio tokens compared to well-established mel-spectrogram features across various speaker and speech related tasks. In this paper, we evaluate compression based audio tokens on three tasks: Speaker Verification, Diarization and (Multi-lingual) Speech Recognition. Our findings indicate that (i) the models trained on audio tokens perform competitively, on average within $1\%$ of mel-spectrogram features for all the tasks considered, and do not surpass them yet. (ii) these models exhibit robustness for out-of-domain narrowband data, particularly in speaker tasks. (iii) audio tokens allow for compression to 20x compared to mel-spectrogram features with minimal loss of performance in speech and speaker related tasks, which is crucial for low bit-rate applications, and (iv) the examined Residual Vector Quantization (RVQ) based audio tokenizer exhibits a low-pass frequency response characteristic, offering a plausible explanation for the observed results, and providing insight for future tokenizer designs.Comment: Preprint. Submitted to ICASSP 202

Accidental Learners: Spoken Language Identification in Multilingual Self-Supervised Models

In this paper, we extend previous self-supervised approaches for language identification by experimenting with Conformer based architecture in a multilingual pre-training paradigm. We find that pre-trained speech models optimally encode language discriminatory information in lower layers. Further, we demonstrate that the embeddings obtained from these layers are significantly robust to classify unseen languages and different acoustic environments without additional training. After fine-tuning a pre-trained Conformer model on the VoxLingua107 dataset, we achieve results similar to current state-of-the-art systems for language identification. More, our model accomplishes this with 5x less parameters. We open-source the model through the NVIDIA NeMo toolkit.Comment: Submitted to ICASSP 202

CORTICAL REPRESENTATION OF SPEECH IN COMPLEX AUDITORY ENVIRONMENTS AND APPLICATIONS

Being able to attend and recognize speech or a particular sound in complex listening environments is a feat performed by humans effortlessly. The underlying neural mechanisms, however, remain unclear and cannot yet be emulated by artificial systems. Understanding the internal (cortical) representation of external acoustic world is a key step in deciphering the mechanisms of human auditory processing. Further, understanding neural representation of sound finds numerous applications in clinical research for psychiatric disorders with auditory processing deficits such as schizophrenia. In the first part of this dissertation, cortical activity from normal hearing human subjects is recorded, non-invasively, using magnetoencephalography in two different real-life listening scenarios. First, when natural speech is distorted by reverberation as well as stationary additive noise. Second, when the attended speech is degraded by the presence of multiple additional talkers in the background, simulating a cocktail party. Using natural speech affected by reverberation and noise, it was demonstrated that the auditory cortex maintains both distorted as well as distortion-free representations of speech. Additionally, we show that, while the neural representation of speech remained robust to additive noise in absence of reverberation, noise had detrimental effect in presence of reverberation, suggesting differential mechanisms of speech processing for additive and reverberation distortions. In the cocktail party paradigm, we demonstrated that primary like areas represent the external auditory world in terms of acoustics, whereas higher-order areas maintained an object based representation. Further, it was demonstrated that background speech streams were represented as an unsegregated auditory object. The results suggest that object based representation of auditory scene emerge in higher-order auditory cortices. In the second part of this dissertation, using electroencephalographic recordings from normal human subjects and patients suffering from schizophrenia, it was demonstrated, for the first time, that delta band steady state responses are more affected in schizophrenia patients compared with healthy individuals, contrary to the prevailing dominance of gamma band studies in literature. Further, the results from this study suggest that the inadequate ability to sustain neural responses in this low frequency range may play a vital role in auditory perceptual and cognitive deficit mechanisms in schizophrenia. Overall this dissertation furthers current understanding of cortical representation of speech in complex listening environments and how auditory representation of sounds is affected in psychiatric disorders involving aberrant auditory processing

Comparison of tamsulosin hydrochloride versus tamsulosin hydrochloride and deflazacort in relieving postoperative urinary retention in patients undergoing transurethral resection of prostate: a prospective randomized controlled trial in a tertiary care centre

Background: Benign prostatic hyperplasia (BPH) is common amongst the elderly. Even after transurethral resection of prostate (TURP), retention of urine may persist in some leading to significant morbidity adversely affecting the quality of life. The role of alpha blockers in this situation as a combination is unclear. The present study was conducted to evaluate and compare the efficacy of tamsulosin versus tamsulosin and deflazacort in relieving the postoperative retention of urine following TURP. Methods: After obtaining ethics approval and written informed consent, 72 patients satisfying the eligibility criteria were included. After TURP, patients with urinary retention following catheter removal were randomized into group A (tamsulosin hydrochloride) and group B (tamsulosin hydrochloride and deflazocort). baseline international prostate symptom score (IPSS) score was done to assess quality of life and findings of radiological investigations were noted. Thereafter, medical therapy was done as per assigned group and postoperative findings were documented and analyzed. Results: Both the groups were similar in terms of demographic characteristics and baseline characteristics. The relief of symptoms was significantly more in group B along with lower IPSS score and residual volume. Conclusions: We recommend addition of deflazacort to tamsulosin hydrochloride as medical therapy for the management of postoperative retention of urine (POUR), especially following TURP

Mixed adsorption and surface tension prediction of nonideal ternary surfactant systems

To deal with the mixed adsorption of nonideal ternary surfactant systems, the regular solution approximation for nonideal binary surfactant systems is extended and a pseudo-binary system treatment is also proposed. With both treatments, the compositions of the mixed monolayer and the solution concentrations required to produce given surface tensions can be predicted based only on the gamma-LogC curves of individual surfactants and the pair interaction parameters. Conversely, the surface tensions of solutions with different bulk compositions can be predicted by the surface tension equations for mixed surfactant systems. Two ternary systems: SDS/Hyamine 1622/AEO7, composed of homogeneous surfactants, and AES/DPCl/AEO9, composed of commercial surfactants, in the presence of excess NaCl, are examined for the applicability of the two treatments. The results show that, in general, the pseudo-binary system treatment gives better prediction than the extended regular solution approximation, and the applicability of the latter to typical anionic/cationic/nonionic nonideal ternary surfactant systems seems to depend on the combined interaction parameter, $${\mathop {(\beta }\nolimits_{an}^s } + {\mathop \beta \nolimits_{cn}^s })/2 - {\mathop \beta \nolimits_{ac}^s }/4$$ : the more it deviates from zero, the larger the prediction difference. If $${\mathop {(\beta }\nolimits_{an}^s } + {\mathop \beta \nolimits_{cn}^s })/2 - {\mathop \beta \nolimits_{ac}^s }/4$$ rarr0, good agreements between predicted and experimental results can be obtained and both treatments, though differently derived, are interrelated and tend to be equivalent

Comparison of stent-related symptoms, passive ureter dilatation and stone clearance rate using 4.5 French versus 6 French double J stenting of unfavourable ureter: a prospective randomized controlled trial in a tertiary care centre

Background: Retrograde intrarenal surgery (RIRS) is the standard of care for renal stones of less than 1.5 cm and less than 1000 Hounsfield units (HU). Most virgin ureters do not allow the flexible ureteroscope in the first setting. Placement of a D-J stent in the ureter dilates the ureter. Therefore, our study aimed to compare stone clearance rates and symptom complex of passive ureteral dilation following 4.5 French/Fr versus 6 French/Fr double J (DJ) stent placement. Methods: After obtaining ethics approval and written informed consent, 100 patients satisfying the inclusion and exclusion criteria were included and data recorded. patients were randomized into group A (4.5 Fr) and group B (6 Fr). Stent was placed. After 4 weeks, symptoms were assessed by the ureteral stent symptom questionnaire (USSQ). Following retrograde intrarenal surgery (RIRS) successful passage of ureteric access sheath (UAS) and stone clearance rates were assessed. Results: The surgical success rate, stone clearance rate was similar in the two groups (p value: more than 0.05). The USSQ score was significantly lower in group A (p value: 0.001). Conclusions: Stent of smaller diameter (4.5 Fr) is associated with less patient discomfort with similar surgical completion rates and stone clearance