Weldability of Advanced High Strength Steels using Yb:YAG high power laser for Tailor-Welded Blank applications

Use of a high power Yb:YAG laser is investigated for joining advanced high strength steel materials for use in tailor-welded blank (TWB) applications. TWB\u27s are materials of different chemistry, coating or thicknesses that are joined before metal forming and other operations such as trimming, assembly and painting are carried out. TWB is becoming an important design tool in the automotive industry for reducing weight, improving fuel economy and passenger safety, while reducing the overall costs for the customer. Three advanced high strength steels, TRIP780, DP980 and USIBOR, which have many unique properties that are conducive to achieving these objectives, along with mild steel, are used in this work. The objective of this work is to ensure that high quality welds can be obtained using Yb:YAG lasers which are also becoming popular for metal joining operations, since they produce high quality laser beams that suffer minimal distortion when transported via fiber optic cables. Various power levels and speeds for the laser beam were used during the investigation. Argon gas was consistently used for shielding purposes during the welding process. After the samples were welded, metallographic examination of the fusion and heat-affected zones using optical and scanning electron microscopes were carried out to determine the microstructures as well as weld defects. Optical and scanning electron microscopes were also used to examine the top of welds as well as fracture surfaces. Additionally, cross-weld microhardness evaluations, tensile tests using Instron tester, limited fatigue tests as well as formability evaluations using OSU plane strain evaluation were carried out. The examinations included a 2-factor full factorial design of experiments to determine the impact of coatings on the surface roughness on the top of the welds. Tensile strengths of DP980, TRIP780 and mild steel materials as well as DP980 welded to TRIP780 and mild steel in the rolling direction as well as transverse direction were evaluated. Metallographic examinations determined that most of the fusion zone is martensitic with small regions of bainite and ferrite. High microhardness values of the order of 550 - 600 Hv were noted in most joints, which are attributed to high alloy content of the fusion zone as well as high rates of cooling typical of laser welds. During tensile, fatigue and formability tests, no fractures in the fusion or heat affected zones were observed. Geometric variability evaluations indicated that coatings such as aluminum (in the case of USIBOR) and galvanized zinc (TRIP780) can affect the variability of the weld zone and the surface roughness on the top of the weld. Excessive variability in the form of weld concavity in the weld zones can lead to fractures in the weld region, even though higher hardness can, to some extent, compensate for these surface irregularities. The 2-factor design of experiments further confirmed that coatings adversely affect the surface roughness on the top of the welds. Although thickness differentials alone do not make a significant impact on surface roughness, together with coatings, they can have an adverse effect on roughness. Tensile tests in the direction of rolling as well as in the transverse direction indicate that TRIP780 seems weaker in the direction of rolling when compared to transverse direction while mild steel is stronger in the direction of rolling. Weldability analyses revealed that the typical melting efficiency is on the order of 50-70% for full penetration welding. Formability tests showed that TR/MS joints fractured in a direction parallel to the weld line when tested with the loads perpendicular to the weld line. Tests have also confirmed that weld speed and power have no impact on the outcome of formability results. Overall, this work conclusively proves that high power Yb:YAG lasers can effectively join high strength materials such as DP980, TRIP780, USIBOR, as well as mild steel, for use in tailor-welded blank applications, contributing to lighter, more fuel-efficient and safer vehicles

Occurrence of House Sparrow, Passer Domesticus Indicus in and around Bangalore

Birds are often common denizens of the ecosystem and have been considered as an indicator species of inhabited areas1. Studies showed that depressed abundance of various bird species in most parts of the world today, especially in urban areas, is of particular concern as many cities are growing rapidly both in area and population2,3. Among the various species of birds, the house sparrow Passer domesticus indicus (Passeriformes: Ploceidae) is one of the familiar species that has followed man everywhere and is inseparable from human habitations. The nonmigratory sparrows are widely distributed in the Indian subcontinent and occur worldwide

Efficient modular arithmetic units for low power cryptographic applications

The demand for high security in energy constrained devices such as mobiles and PDAs is growing rapidly. This leads to the need for efficient design of cryptographic algorithms which offer data integrity, authentication, non-repudiation and confidentiality of the encrypted data and communication channels. The public key cryptography is an ideal choice for data integrity, authentication and non-repudiation whereas the private key cryptography ensures the confidentiality of the data transmitted. The latter has an extremely high encryption speed but it has certain limitations which make it unsuitable for use in certain applications. Numerous public key cryptographic algorithms are available in the literature which comprise modular arithmetic modules such as modular addition, multiplication, inversion and exponentiation. Recently, numerous cryptographic algorithms have been proposed based on modular arithmetic which are scalable, do word based operations and efficient in various aspects. The modular arithmetic modules play a crucial role in the overall performance of the cryptographic processor. Hence, better results can be obtained by designing efficient arithmetic modules such as modular addition, multiplication, exponentiation and squaring. This thesis is organized into three papers, describes the efficient implementation of modular arithmetic units, application of these modules in International Data Encryption Algorithm (IDEA). Second paper describes the IDEA algorithm implementation using the existing techniques and using the proposed efficient modular units. The third paper describes the fault tolerant design of a modular unit which has online self-checking capability --Abstract, page iv

Polymorphic phase transformation of Degussa P25 TiO2 by the chelation of diaminopyridine on TiO6 2- octahedron: Correlation of anatase to rutile phase ratio on the photocatalytic activity

A series of nitrogen-doped Degussa P25 photocatalysts were synthesized successfully by grinding and calcination method using 2,6-diaminopyridine (DAP) as a nitrogen precursor. The prepared samples were characterized by various analytical methods. The phase contents of anatase and rutile in the Degussa P25 powders have been altered by simply changing the proportion of DAP. A mechanism involving chelated DAP molecule on TiO6 2- octahedron is discussed. The enhanced activity is attributed to synergistic effect in the two phase solid material. Due to the low activation barrier, the effective inter particle electron transfer between the two polymorphs is quite efficient only when they are in close proximity with similar crystallite sizes. The transfer of electrons from the rutile phase to lattice/electron trapping sites of anatase and also to the Ti3+-Vo defect level created by the dopant favors effective charge separation and enhance the photocatalytic activity under solar illumination. © 2013 Elsevier B.V. © 2013 Elsevier B.V. All rights reserved

Numerical solution to Eighth order Linear Differential Equation Using the Octic B-spline collocation Method

In this paper, Collocation method using recursive form of Octic degree B-spline functions as basis is developed and employed to find the numerical solution for eighth order differential equation with boundary condition problems. Numerical examples are considered to test the performance, stability and accuracy of the present developed method

EVALUATION OF THE ADDED EFFECT OF SHUNTYADI KWATHA IN THE MANAGEMENT OF AMAVATA VIS A VIS RHEUMATOID ARTHRITIS

Amavata is a very painful condition due to Vata prakopa avastha, and when Vata is accompanied with Ama then severity of pain increases more. Vitiated Vayu circulates the Ama all over the body through  Dhamanies, takes shelter in the Shleshma Sthana (Amashaya, Sandhi, etc.), producing symptoms such as stiffness, swelling, and tenderness in small and big joints, making a person lame. The symptoms of Amavata are identical to rheumatism, which include rheumatoid arthritis and rheumatic fever. Shunthi is a very common household drug, almost everyone have used ginger in so many things as in tea or in curry etc. In all living beings pain is one of the nature’s earliest sign of morbidity. first and foremost duty of a physician is to help a patient to get rid of pain. The conventional science tries to find a cure for this through analgesics, steroidal therapy, etc. which often results in ill effects. Here comes the importance of herbal remedies of Ayurveda. Shuntyadi kwatha show a wide range of therapeutic usages. Because of its properties like Ushanta, Tikshanta, Katu, Tikta rasa, Katu vipaka help in Samprapti vighatana of Aamavata. when Shuntyadi kwatha is used with Simhanada guggulu then, its result increases many fold in Amavata. In this study 40 patients of Amavata were registered and 03 patient (6.66%) were got no improvement, 15 patients got mild -improvement, 22 patient (10%) were got moderate improvement, 0 patient got Marked improvement and complete cure

EVALUATION OF THE ADDED EFFECT OF AMRUTADI KASHAYA IN THE MANAGEMENT OF AMLAPITTA VIS A VIS ACID DYSPEPSIA

In Ayurvedic text Mandagni is the main cause of all the Roga including Amlapitta. by the increased Drava guna and Amla guna of Pachaka Pitta affecting the Annavaha, Rasavaha, Raktavaha, Purishvaha srotasa; Samana, Prana, Apana Vayu; mainly Kledaka and partially Bodhaka Kapha. Prana vayu, which having the Karma of Aadana, help the Anna to enter in the Kostha where the Anna gets disintegrated by fluids and softened by unctuous substances. Samana Vayu stimulates the Jatharagni which is situated in Amashaya and as a result proper digestion process starts. Agni performs normal functions when food is consumed in appropriate time and with appropriate and serves as promoter of longevity. Describing the Samprapti of Amlapitta Acharya Charaka says that Aamvisha, when get mixed with Pitta, the disease Amlapitta develops whereas Acharya Kashyapa described that the disease is caused by vitiation of Doshas (Tridosha) causing Mandagni which leads to Vyadhi Amlapitta. Amlapitta can be correlated with Acid Reflux Syndrome which comprises of various types of Gastro-esophageal Reflux Diseases like Gastritis, Dyspepsia, Heartburn, Hyperacidity, Hypoacidity etc. Described in modern sciences. The conventional science tries to find a cure for this through PPI, Antacid therapy, etc. which often results in ill effects. Here comes the importance of herbal remedies of Ayurveda. Amrutadi kashaya show a wide range of therapeutic usages. Because of its properties like Ushanta, Tikshanta, Katu, Tikta rasa, Ushnaa veerya help in Samprapti vighatana of Amlapitta. when Amrutadi kashaya is used with Laghusutashekhara rasa then, its result increases many fold in Amlapitta. In this study 40 patients of Amlapitta were registered and 03 patient (6.66%) were got no improvement, 18 patients got mild -improvement, 19 patient were got moderate improvement, 0 patient got Marked improvement and complete cure

Recent Trends in Digital Library Publications: A Scientometric Analysis

The study seeks to illustrate the most current trends in digital library research via the use of scientometrics. The study of scientific networks is important in many scientific domains. A social network with many nodes and connections serves as the foundation for scientific network research. Nodes include authors, publications, and journals, while linkages include citations, cocitations, and coauthorship. Data was collected from the Scopus abstracting and citation database for the period of ten years from 2012 to 2021. The most relevant 1957 documents were chosen from the collection, and selected documents were analyzed using Biblioshny and VOSviewer. The research showed that digital library productivity is rising annually, the United States of America dominates the production of scholarly production on digital libraries, and research is increasingly focused on digital resource and digital collection development. However, artificial intelligence, deep learning, machine learning, big data, and other related areas of study have emerged as the most recent research trends in digital library research. The outcomes of this study will aid digital library research by providing up-to-date and reliable research information

Numerical Solution to Ninth order Non- Linear Differential Equation Using the Ninth Degree B-Spline Collocation Method

In this paper, Collocation method using recursive form of Ninth degree B-spline functions as basis is developed and employed to find the numerical solution for ninth order boundary value problems. Non linear boundary value problem is considered to test the performance, stability and accuracy of the present developed method