EFFECT OF GMAW TWIN WIRE TANDEM PARAMETERS ON MECHANICAL PROPERTIES OF WELDED JOINTS

Tandem welding has the advantage of higher productivity over a limitation considering narrow groove joints. Tandem has higher deposition and heat input. To study the effect of variation in robotic tandem parameters on fatigue properties of welded joints, the following parameters were investigated, viz. first case root & the second pass using a single wire, subsequent run tandem twin and second case using root pass using a single wire, subsequent run using tandem twin wire welding. Butt joint samples were subjected to ultrasonic testing, mechanical & metallurgical testing, and fatigue testing. Found Group 1 tensile strength, yield strength, % elongation & impact value to be 12 %, 9 %, 23 % & 14 %, respectively, higher than Group 2. Explained variations in microhardness & better fatigue life were observed for Group 1. This investigation will help manufacturers in decision-making while selecting tandem parameters considering productivity or reliability

RELATIONSHIP OF DEW POINT AND AMBIENT TEMPERATURE VARIATION ON WELD QUALITY

This investigation deals with the study of the effect of environmental parameters viz dew point temperature, relative humidity, ambient air temperature, and job surface temperature on robotic MAG (Metal active gas) welded joint quality. Weld samples taken were mass manufacturing welded structures of a heavy-large scale industry, which were further subjected to semi-automatic ultrasonic testing to assess defects within welded joints. The trend of defects observed and recorded after ultrasonic testing of weld joints was co-related with the trend of atmospheric parameters for a span of four years to establish a linear empirical relationship. It has been established that variations in atmospheric parameters resulted in variations in the trend of weld defects. These variations were studied to get the empirical relationship to establish the effect of variation in atmospheric parameters on weld quality or defects in joints. It has been observed that whenever there was a drop in the "difference in ambient air temperature & dew point temperature, especially less than 5", a drop in ultrasonic testing straight pass % was observed than the average value

EFFECT OF PURITY LEVEL OF CO2 SHIELDING ON METAL ACTIVE GAS WELDED JOINT QUALITY

The investigation deals with the study of the effect of the purity level of carbon dioxide shielding gas on the metal active gas weld quality. Studied 99.78 %, 99.95 %, and 99.97 % purity levels of carbon dioxide shielding gas. Factors considered were related to shielding gas purity, moisture, Sulphur, and oxygen content. Welded samples were subjected to ultrasonic testing to assess weld quality. With the reduction in purity level below 99.9 %, it was observed that the weld defect percentage increased in both lab trials and mass manufacturing jobs. The defects recorded were 5% higher when jobs were welded using carbon dioxide supplied from a gas cylinder than that supplied from liquid cryogenic bullets; this established that a higher purity level could be maintained in cryogenic storage and transport of shielding gases. This states helpful references to manufacturing industries for selecting the purity level of shielding gas, with the objective of rework reduction

Seven new combinations in Phanera (Fabaceae: Caesalpinioideae: Cercideae)

Seven new combinations in Phanera Lour. are made for species which were either described in Lasiobema (Korth.) Miq. or later transferred to Lasiobema from Bauhinia L

Titanium Dioxide and Its Applications in Mechanical, Electrical, Optical, and Biomedical Fields

Titanium dioxide (TiO2), owing to its non-toxicity, chemical stability, and low cost, is one of the most valuable ceramic materials. TiO2 derived coatings not only act like a ceramic protective shield for the metallic substrate but also provide cathodic protection to the metals against the corrosive solution under Ultraviolet (UV) illumination. Being biocompatible, TiO2 coatings are widely used as an implant material. The acid treatment of TiO2 promotes the attachment of cells and bone tissue integration with the implant. In this chapter, the applications of TiO2 as a corrosion inhibitor and bioactive material are briefly discussed. The semiconducting nature and high refractive index of TiO2 conferred UV shielding properties, allowing it to absorb or reflect UV rays. Several studies showed that a high ultraviolet protection factor (UPF) was achieved by incorporating TiO2 in the sunscreens (to protect the human skin) and textile fibers (to minimize its photochemical degradation). The rutile phase of TiO2 offers high whiteness, and opacity owing to its tendency to scatter light. These properties enable TiO2 to be used as a pigment a brief review of which is also addressed in this chapter. Since TiO2 exhibits high hardness and fracture toughness, the wear rate of composite is considerably reduced by adding TiO2. On interacting with gases like hydrogen at elevated temperatures, the electrical resistance of TiO2 changes to some different value. The change in resistance can be utilized in detecting various gases that enables TiO2 to be used as a gas sensor for monitoring different gases. This chapter attempts to provide a comprehensive review of applications of TiO2 as an anti-corrosion, wear-resistant material in the mechanical field, a UV absorber, pigment in the optical sector, a bioactive material in the biomedical field, and a gas sensor in the electrical domain

Multilayered and Chemiresistive Thin and Thick Film Gas Sensors for Air Quality Monitoring

Selective detection of gases such as nitrogen dioxide (NO2), carbon monoxide (CO), carbon dioxide (CO2), and various volatile organic components (VOCs) is necessary for air quality monitoring. Detection of hydrogen (H2) is equally important as it is a flammable gas and poses serious threat of explosion when exposed to oxygen gas. We have studied the sensing characteristics of these gases using thin film deposited by chemical solution deposition as well as relatively thicker films deposited by atmospheric plasma spray (APS) process. The chapter starts with the sensing mechanism of chemiresistive sensors followed by the definition of gas sensing parameters. Subsequently, we have demonstrated selective NO2 sensing characteristics of zinc oxide-graphene (ZnO-G) multilayered thin film followed by CO and H2 sensing characteristics of ZnO thin film and SnO2 thick film. Cross-sensitivity among CO and H2 gases has been addressed through the analysis of conductance transients with the determination of activation energy, Ea, and heat of adsorption, Q. The concepts of reversible and irreversible sensing have also been discussed in relation to CO and H2 gases. CO2 sensing characteristics of LaFe0.8Co0.2O3 (LFCO)-ZnO thin film have been elucidated. Interference from CO has been addressed with principal component analyses and the ascertaining of Ea and Q values. Additionally, the variation of response with temperature for each gas was simulated to determine distinct parameters for the individual gases. Further, VOC sensing characteristics of copper oxide (CuO) thin film and WO3-SnO2 thick film were investigated. Principal component analysis was performed to discriminate the gases in CuO thin film. The interaction of WO3-SnO2 thick film with various VOCs was found to obey the Freundlich adsorption isotherm based on which Ea and Q values were determined

Right-Most Position of a Last Progeny Modified Branching Random Walk

In this work, we consider a modification of the usual Branching Random Walk (BRW), where we give certain independent and identically distributed (i.i.d.) displacements to all the particles at the $n$-th generation, which may be different from the driving increment distribution. We call this process last progeny modified branching random walk (LPM-BRW). Depending on the value of a parameter, $\theta$, we classify the model in three distinct cases, namely, the boundary case, below the boundary case, and above the boundary case. Under very minimal assumptions on the underlying point process of the increments, we show that at the boundary case, when $\theta$ takes a particular value $\theta_0$, the maximum displacement converges to a limit after only an appropriate centering, which is of the form $c_1 n - c_2 \log n$. We give an explicit formula for the constants $c_1$ and $c_2$ and show that $c_1$ is exactly the same, while $c_2$ is $1/3$ of the corresponding constants of the usual BRW. We also characterize the limiting distribution. We further show that below the boundary (that is, when $\theta < \theta_0$), the logarithmic correction term is absent. For above the boundary case (that is, when $\theta > \theta_0$), we have only a partial result, which indicates a possible existence of the logarithmic correction in the centering with exactly the same constant as that of the classical BRW. For $\theta \leq \theta_0$, we further derive Brunet--Derrida-type results of point process convergence of our LPM-BRW to a decorated Poisson point process. Our proofs are based on a novel method of coupling the maximum displacement with a linear statistics associated with a more well-studied process in statistics, known as the smoothing transformation.Comment: 32 pages; 3 figure

Lysiphyllum dewitii Bandyop. & Ghoshal 2014, comb. nov.

1.Lysiphyllum dewitii (K. Larsen & S. S. Larsen) Bandyop. & Ghoshal, comb. nov. Bauhinia dewitii K. Larsen & S. S. Larsen, Gard. Bull. Singapore 31: 1. 1978. Type: Borneo, Mt. Doya, Bau, Chai, P., S. 29920 (holotype K000760792, image!, isotypes A00312895 image! (HUH 2014), L0018719 n.v., SING n.v.). DISTRIBUTION: Endemic to Borneo.Published as part of Bandyopadhyay, Subir & Ghoshal, Partha Pratim, 2014, Two new combinations in Lysiphyllum (Leguminosae-Caesalpinioideae), pp. 298-300 in Phytotaxa 178 (4) on page 298, DOI: 10.11646/phytotaxa.178.4.3, http://zenodo.org/record/514565