Scenario/Class Diagram Synthesis

The scenario-synthesis problem in requirements analysis is explored in this report.The approach suggested by Khriss et al.is adapted for the domain of Digital Libraries. The results of the synthesis along with the entire transformation process are elaborated in this report

A study on welding quality of robotic arc welding process using Mahalanobis distance method

In robotic GMA (Gas Metal Arc) welding process, heat and mass inputs are coupled and transferred by the weld arc and molten base material to the weld pool. The amount and distribution of the input energy are basically controlled by the obvious and careful choices of welding process parameters in order to accomplish the optimal bead geometry and the desired mechanical properties of the quality weldment. To make effective use of automated and robotic GMA welding, it is imperative to predict online faults for bead geometry and welding quality with respect to welding parameters, applicable to all welding positions and covering a wide range of material thickness. To successfully accomplish this objective, two sets of experiment were performed with different welding parameters; the welded samples from SM 490A steel flats adopting the bead-on-plate technique were employed in the experiment. The experimental results of current and voltage waveforms were used to predict the magnitude of bead geometry and welding quality, and to establish the relationships between weld process parameters and online welding faults. MD (Mahalanobis Distance) technique is employed for investigating and modeling of GMA welding process and significance test techniques were applied for the interpretation of the experimental data. Statistical models developed from experimental results which can be used to control the welding process parameters in order to achieve the desired bead geometry based on weld quality criteria

Schizophrenia-associated somatic copy-number variants from 12,834 cases reveal recurrent NRXN1 and ABCB11 disruptions

While germline copy-number variants (CNVs) contribute to schizophrenia (SCZ) risk, the contribution of somatic CNVs (sCNVs)—present in some but not all cells—remains unknown. We identified sCNVs using blood-derived genotype arrays from 12,834 SCZ cases and 11,648 controls, filtering sCNVs at loci recurrently mutated in clonal blood disorders. Likely early-developmental sCNVs were more common in cases (0.91%) than controls (0.51%, p = 2.68e−4), with recurrent somatic deletions of exons 1–5 of the NRXN1 gene in five SCZ cases. Hi-C maps revealed ectopic, allele-specific loops forming between a potential cryptic promoter and non-coding cis-regulatory elements upon 5′ deletions in NRXN1. We also observed recurrent intragenic deletions of ABCB11, encoding a transporter implicated in anti-psychotic response, in five treatment-resistant SCZ cases and showed that ABCB11 is specifically enriched in neurons forming mesocortical and mesolimbic dopaminergic projections. Our results indicate potential roles of sCNVs in SCZ risk

Numerical and experimental study of residual stress and strain in multi - pass GMA welding

Purpose: Recently, manufacturing industries have been concentrated on selection an optimal of welding parameter and condition that reduces the risk of mechanical failures on weld structures should be required in manufactory industry. In robotic GMA (Gas Metal Arc) welding process, heat and mass inputs are coupled and transferred by the weld arc to the molten weld pool and by the molten metal that is being transferred to the weld pool. The amount and distribution of the input energy are basically controlled by the obvious and careful choices of welding process parameters in order to accomplish the optimal bead geometry and the desired mechanical properties of the quality weldment. The residual stress and welding deformation have the large impact on the failure of welded structures. Design/methodology/approach: To achieve the required precision for welded structures, it is required to predict the welding distortions at the early stages. Therefore, this study represented 2D Finite Element Method (FEM) to predict residual stress and strain on thick SS400 steel metal plate. Findings: The experiment for Gas Metal Arc (GMA) welding process is also performed with similar welding condition to validate the FE results. The simulated and experiment results provide good evidence that heat input is main dependent on the welding parameter and residual stress and distortions are mainly affected by amount on heat input during each weld-pass. Practical implications: This present study on based on the numerical analysis using ansys software, for a thick multi-pass GMA welding. A birth and death technique is employed to control the each weld pass welding. Originality/value: The developed 2D multi-pass model employs Goldak’s heat distribution, to simulate welding on SS400 steel butt-weld joint with a thickness of 16mm. moreover the numerical results are validated with experiment results

A study on simulation model and kinematic model of welding robot

Purpose: This study tries to develop a simulation model of six degree freedom for Faraman AM1 welding robot using CATIA V5 and compares with the computed kinematic model for robotic welding. The error varification of simulated model and kinematics of the robot is also being carried out. Design/methodology/approach: CATIA (Computer Aided Three dimensional Interactive Application) is a multi-platform PLM/CAD/CAM/CAE commercial software suite to use to develop six degree freedom for Faraman AM1 welding robot. The forward kinematic and inverse kinematic equations are also used to verify the developed model. Findings: The results obtained from the six degree freedom for Faraman AM1 simulated model has a good agreement with computed kinematic models equations. The catia V5 a very powerful tool which could used in develope a simulation for robotic welding system. The the angle error between simulated model and computed inverse kinmenatic equation obtained too very small. Research limitations/implications: The developed simulated in Catia is mainly aimed to be used in GMA welding process. D-H (Denavit-Hartenberg) convection is used to determine the orthonormal coordinate frames at different joints of a robotic manipulator and determining four kinematic parameters. Originality/value: The six degree freedom for Faraman AM1 welding robot is model to analysed and compared with forward and inverse knimatic

Prediction welding quality in multi - pass welding process using Mahalanobis distance method

The welding quality in multi-pass welding is mainly dependent on the pre-heating from previous pass or root-pass welding. In this study, a Mahalanobis Distance and normal distribution method is illustrated and employed to determine whether welding faults have occurred after each pass welding and also to quantify welding quality percentage. To successfully accomplish this objective, sets of multi-pass welding experiment were performed with different welding parameters in each pass; the welded samples of SS400 steel flats adopting the bead-on-plate technique were employed in the experiment. The result of current and voltage for each pass is obtained through the real time mentoring systems. In order to verify the effect of the performance and weld quality of the different weld-pass, Mahalanobis distances for voltage and current values were calculated and used for qualitative and quantitative analysis with comparison to values obtained from the root-pass as reference welds. The results of the experiment and statistical analysis have demonstrated that the weld faults after each weld pass is feasible

Assessment of Depression, Anxiety and Stress among Healthcare Students during COVID-19 Pandemic: A Cross Sectional Study

Background: A Corona virus pandemic now has had a huge impact on quality of life all around the world. People's mental health has been affected by quarantine. The economic delays could have long term impacts on the psychology of students as they are more likely to be graduated later than they have expected. The number of factors contributed to gravitate the psychological disturbances including online education, financial worries and academic pressure. Aims and Objectives: This Study was to determine the level of Depression, Anxiety and Stress among Students during COVID-19 Pandemic. Furthermore, to see if there's a correlation between demographic profile and the DASS-21. Materials and methods: A cross-sectional survey was conducted among the healthcare students using DASS-21 which included a conventional DASS questionnaire along with demographic characteristics. A Google form link was shared through social media-WhatsApp and E-mail and data was collected and analyzed using excel sheet to examine the levels of depression, anxiety, and stress among students. Results: The study enrolled a total of 303 students. The prevalence of moderate depression, anxiety, and stress was found to be 37.9%, 337.9%, 34.9% and 33%, respectively. Males were represented up to 54.13 percent of the population, while females accounted for 45.87 percent. Female responders were more likely than their male counterparts to experience depression and anxiety, whereas stress levels were found to be comparable in both genders. Conclusion: The average scores of depression, anxiety, and stress in this study were significantly high. Depression, anxiety, and stress are now all associated with a variety of causes. Students develop depression and anxiety as a result of a lack of academic and social life. Students may be stressed due to a lack of exercise and economic difficulties. Keywords: Depression, DASS-21, Mental Health, Pandemic, Students, Social Lif

Numerical and experiment study of residual stress and strain in multi - pass GMA welding

There must selection an optimal of welding parameter and condition that reduces the risk of mechanical failures on weld structures.The residual stress and welding deformation have the large impact on the failure of welded structures.To achieve the required precision for welded structures, it is required to predict the welding distortions at the early stages.Therefore, this study uses 2DFinite Element Method (FEM) to predict residual stress and strain on thick SS400 steel metal plate. A birth and death technique is employed to control the each weld pass welding. Gas Metal Arc (GMA) welding experiment is also performed with similar welding condition to validate the FE results.The simulated and experiment results provide good evidence that heat input is main dependent on the welding parameter and residual stress and distortions are mainly affected by amount on heat input during each weld-pass

Numerical studies on residual stress and strain distribution in Thick-Welded Plate

In this study, a numerical method is used to investigate the effect of welding parameter and cooling time on residual stress and strain in the multi-pass butt Gas Metal Arc (GMA) welding process, while plate is restrained in transverse direction of welding direction. Two dimension finite element simulations were implemented to predict the welding temperature distributions, residual stress and strain on 16mm thick SM490 steel plate for different input welding parameter at each weld pass using Ansys software. Not only the temperature dependent thermal properties were considered, but also birth and death technique is employed to control the process of weld filling. The simulated results provide good evidence that residual stress and strain is mainly dependent on heat load, welding parameter and restraints on material. The large amount of residual stress and strain is being developed around the Heat Affected Zone, Fusion zone and welding regions. The elastic FE model can be used to predict precisely the welding deformation and residual stress in a thick multi pass butt welding. Furthermore, the extensive experiment effort of component testing could be reduced adequate and deliberate application of welding FE simulation