Machine Tool Crack Detection using Operational Modal Characteristics

Machine tool crack detection is to detect any damages in the tool during machining and to predict the breakage of the tool by identifying the appearance of small cracks in the tool during machining. Machine tool state monitoring is critical for controlling the work piece quality and production continuity in the case of mass production. For assessing tool breakage, machine tool vibration monitoring is a suitable means. The results obtained in FE analysis are validated with experimental data. This work gives a methodology for online crack detection in machine tools. This work presents an experimental technique for measuring modal parameters of a rectangular aluminium plate with cantilever boundary condition using only the output data, with the intention to apply the technique to machine tools. Operational modal analysis is be used for damage detection by determining the depth as well as the position of tool cracks. The results obtained are validated with finite element analysis. To locate the crack, 3D graphs of the normalized frequency in terms of the crack depth and location are plotted. The intersection of these contours gives crack location and crack depth. Out of several case studies conducted the results of one of the case study is presented to demonstrate the applicability and efficiency of the method suggested

Measurement Of Film Thickness And Temperature On Horizontal Metal Spray Coated Tube Falling Film Evaporator Using Interferometric Techique

’Water’ is the ’Essence of Life’. It is an irreplaceable precious resource that is core of life on earth, a vital commodity that is critical for human survival, socio-economic developments and for the preservation of a healthy ecosystem. Current trends indicate that two-thirds of the world’s population will be living in water-stressed countries by 2025(wat (2006)). In order to eradicate or to provide sufficient water requirement for mankind desalination plays a pivotal role. This paper presents studies on horizontal tube falling film evaporator for Multi effect desalination (MED) system with spray coated tubes. The most important component in any MED system is the falling film evaporator. The wide acceptance for this kind of evaporators is because of the fact that it is characterized by a very low-pressure drop. In MED systems, falling film evaporation takes place outside the tube geometry utilizing the latent heat of condensing vapour inside the tube. Convective evaporation, as well as low-temperature nucleate boiling, occur in the film as it flows over the tube depending on the operating conditions(Abraham and Mani (2015)). The liquid falls on the top of the tube and flows down along the curved tube surface. There is a phase change on both sides of the tube and the evaporation outside the tube helps vapour to be separated from the liquid as soon as it is formed. Two different tubes surfaces were studied, namely bare copper tube and copper tube coated with alloy of Al2O3 and TiO2. Scanning electron microscope, Energy-dispersive X-ray spectroscopy, 3D surface profilometer were utilized to study about the surface texture, composition and to find surface roughness values attributed with each tubes. An optical shadow method (non-intrusive) incorporating Otsus’s algorithm was used to evaluate the film thickness around the circumference of the cylinder, and a Mach-Zehnder Interferometer (MZI) was employed to visualize the isotherm formation (Maliackal et al. (2021)). All studies were performed for complete wetting of the tube. The measured film thickness was compared with commonly used empirical formulas. Further, the effectiveness of using those empirical formulas for small diameter tubes was analyzed. A novel interferometric technique was used to analyze the film interface temperature, and a comparative study was performed for the two different tube geometries. A standard error of mean (SEM) analysis was performed on every data set

Copper complexes as chemical nucleases

Redox active mononuclear and binuclear copper(II) complexes have been prepared and structurally characterized. The complexes have planar N-donor heterocyclic bases like 1,10-phenanthroline (phen), dipyridoquinoxaline (dpq) and dipyridophenazine (dppz) ligands that are suitable for intercalation to B-DNA. Complexes studied for nuclease activity have the formulations [Cu(dpq)2(H2O)] (ClO4)2.H2O (1), [CuL(H2O)2(μ-ox)](ClO4)2 (L = bpy,2; phen,3; dpq,4; and dppz,5) and [Cu(L)(salgly)] (L = bpy,6; phen,7; dpq,8; and dppz,9), where salgly is a tridentate Schiff base obtained from the condensation of glycine and salicylaldehyde. The dpq complexes are efficient DNA binding and cleavage active species. The dppz complexes show good binding ability but poor nuclease activity. The cleavage activity of thebis-dpq complex is significantly higher than thebis-phen complex of copper(II). The nuclease activity is found to be dependent on the intercalating nature of the complex and on the redox potential of the copper(II)/copper(I) couple. The ancillary ligand plays a significant role in binding and cleavage activity

Impact of metal on the DNA photocleavage activity and cytotoxicity of ferrocenyl terpyridine 3d metal complexes

Ferrocenyl terpyridine 3d metal complexes and their analogues, viz. [M(Fc-tpy)2](ClO4)2 (1-4), [Zn(Ph-tpy)2](ClO4)2 (5) and [Zn(Fc-dpa)2]X2 (X = ClO4, 6; PF6, 6a), where M = Fe(II) in 1, Co(II) in 2, Cu(II) in 3 and Zn(II) in 4, Fc-tpy is 4'-ferrocenyl-2,2':6',2''-terpyridine, Ph-tpy is 4'-phenyl-2,2':6',2''-terpyridine and Fc-dpa is ferrocenyl-N,N-dipicolylmethanamine, are prepared and their DNA binding and photocleavage activity in visible light studied. Complexes 2, 4, 5 and 6a that are structurally characterized by X-ray crystallography show distorted octahedral geometry with the terpyridyl ligands binding to the metal in a meridional fashion, with Fc-dpa in 6a showing a facial binding mode. The Fc-tpy complexes display a charge transfer band in the visible region. The ferrocenyl (Fc) complexes show a quasi-reversible Fc+-Fc redox couple within 0.48 to 0.66 V vs. SCE in DMF-0.1 M TBAP. The DNA binding constants of the complexes are 104 M-1. Thermal denaturation and viscometric data suggest DNA surface binding through electrostatic interaction by the positively charged complexes. Barring the Cu(II) complex 3, the complexes do not show any chemical nuclease activity in the presence of glutathione. Complexes 1-4 exhibit significant plasmid DNA photocleavage activity in visible light via a photoredox pathway. Complex 5, without the Fc moiety, does not show any DNA photocleavage activity. The Zn(II) complex 4 shows a significant PDT effect in HeLa cancer cells giving an IC50 value of 7.5 µ M in visible light, while being less toxic in the dark (IC50 = 49 µ M)

Record sized Alepes vari and Nematalosa nasus

The herring scad, Alepes vari is a common pelagic fish species in the family carangidae. The species is the largest fish of the scad genus Alepes and maximum length so far recorded all over the world oceans is 560 mm TL (Froese & Pauly, FishBase 2016, http://www.fishbase.org.). During a regular field visit, an unusually large specimen of A. vari was recorded from Kalamukku Landing Centre, Kerala on 25th May, 2016. This was a male individual measuring 600 mm in total length (TL) and weighing 1.6 kg (Fig. 1)and was caught by hook and line. Young ones occasionally occur in pelagic trawls and larger ones rarely occur in gill net and hook and line catches

Rare occurrence of Bombay duck from Central Kerala

The occurrence of Bombay duck along south coast of India is very rare, especially Kerala coast. On 4th December, 2019, one specimen of Bombayduck, Harpadon nehereus measuring 252 mm in total length and weighing 114.5 g was landed at Chellanam landing centre, Kochi (9°47'56.8"N 76°16'32.2"E) by an outboard ringseiner unit operated at a depth of 30-50 m targeting Indian oil sardine. Morphometric and meristic characters of the specimen landed were recorde

Metal-assisted red light-induced efficient DNA cleavage by dipyridoquinoxaline-copper(II) complex

Complete cleavage of double stranded pUC19 DNA by the complex [Cu(dpq)2(H2O)](ClO4)2 (dpq, dipyridoquinoxaline) has been observed on irradiation at 694 nm from a pulsed ruby laser, assisted by the metal d-band transition as well as the quinoxaline triplet states in the absence of any external additives

Evolving market chains for Indian oil sardine

Indian oil sardine, Sardinella longiceps forms a major catch of traditional fisherman in Kerala throughout the year. After the peak landing of nearly four lakh tonnes in 2012, catches have showed a continuous decline to less than 50000 t in 2019. This trend has adversely affected the livelihoods of thousands of traditional fishermen. Oceanographic changes associated with El Niño has been identified as one of the reasons for this decline in sardine catches along the Kerala coas

Length-weight relationships (LWRs) of Coryphaena hippurus (Linnaeus, 1758) and Coryphaena equiselis (Linnaeus, 1758) from Southeastern Arabian Sea

This study reports the length-weight relationships of two dolphinfish species, namely Coryphaena hippurus (Linnaeus, 1758) and C. equiselis (Linnaeus, 1758) in the south-eastern Arabian Sea. Specimens in various length groups belonging to both the species were collected between April 2012 and May 2017 from Kerala waters, south-west coast of India. The fishes were caught by hook and line (hook no: VI-X) and drift gill net (mesh size: 90-160 mm). The length-weight relationships were established as TW = 0.0217FL2.786 (r2= 0.967) for C. hippurus and TW = 0.0183FL2.891 (r2=0.993) for C. equiselis