Modelling of GTAW Weld Pool under Marangoni Convection

With several different fusion welding processes, the melted weld pool profile which ultimately solidifies to form the fusion zone, diverging greatly by a wide variety of factors, e.g. base material, workpiece size, machine setups and extensive range of other process variables. For each distinctive welding setup, the weld pool geometry could vary considerably, and thought to be largely dependent on the hydrodynamics of the weld pools [1]. The Marangoni Effect or thermo-capillarity is seen to be the a dominant force influencing weld pool flow patterns under Gas Tungsten Arc Welding (GTAW), inducing liquid metal to flow to regions with higher surface tension (γ) caused by surface tension thermal gradients ∂γ⁄∂T, this in turn would greatly alter the weld pool thermal history, hence the fusion zone geometry [2]. As a general trend, for a negative ∂γ⁄∂T, outward flow from the pool centre to the edge tends to produce wide and shallow pools; whereas for a positive ∂γ⁄∂T, the liquid metal would flow inward to the pool centre, thus creating deep and narrow pool shapes [3]. Fig. 1 Schematic illustration of GTAW process with negative surface tension temperature gradient. This research group believes that the Marangoni Effect is the dominant force in weld pool shaping. To better understand the weld pool behaviours, a two-dimensional simulation model was constructed in CFD package Fluent®, based on stationary arc GTAW welding conditions. In addition, GTAW welding experiments were also performed on titanium alloy Ti-5Al-5Mo-5V-3Cr as reference data for the numerical results to evaluate against

Mechanical Properties and Microstructure of Laser Welded Ti-6Al-2Sn-4Zr-2Mo (Ti6242) Titanium Alloy

Room temperature tensile properties and microhardness of a laser welded Ti–6Al–2Sn–4Zr–2Mo (Ti6242) titanium alloy sheet were examined and correlated to the microstructure evolution across the weld. Tensile testing integrated with the optical image correlation Instron® system indicated that the average yield strength (YS), ultimate tensile strength (UTS), and total elongation of the weldment were respectively 88%, 87%, and 69% of the corresponding base material (BM) values. Electron probe microanalysis (EPMA) demonstrated a uniform distribution of the main alloying elements across the weld. The hardness raised increasingly from the BM toward the heat affected zone (HAZ) and the fusion zone (FZ) due to mainly a higher α volume fraction in HAZ and acicular α′ martensite formation in the FZ. Because of the higher hardness of the HAZ and FZ, a higher YS for the weldment relative to the BM would be expected. However, the lower YS as well as the lower UTS of the weldment can be explained by presence of some porosity and underfill in the FZ. The lower total elongation of the weldment compared to the BM can be related to the higher hardness of the HAZ and FZ.Room temperature tensile properties and microhardness of a laser welded Ti-6Al-2Sn-4Zr-2Mo (Ti6242) titanium alloy sheet were examined and correlated to the microstructure evolution across the weld. Tensile testing integrated with the optical image correlation Instron® system indicated that the average yield strength (YS), ultimate tensile strength (UTS), and total elongation of the weldment were respectively 88%, 87%, and 69% of the corresponding base material (BM) values. Electron probe microanalysis (EPMA) demonstrated a uniform distribution of the main alloying elements across the weld. The hardness raised increasingly from the BM toward the heat affected zone (HAZ) and the fusion zone (FZ) due to mainly a higher α volume fraction in HAZ and acicular α' martensite formation in the FZ. Because of the higher hardness of the HAZ and FZ, a higher YS for the weldment relative to the BM would be expected. However, the lower YS as well as the lower UTS of the weldment can be explained by presence of some porosity and underfill in the FZ. The lower total elongation of the weldment compared to the BM can be related to the higher hardness of the HAZ and FZ

Hubungan Antara Beban Kerja Dengan Stres Kerja Pada Perawat Pelaksana Di Ruang Isolasi Covid-19 Rumah Sakit Umum Daerah Kota Kotamobagu

Dampak dari wabah Coronavirus Disease of 2019 (COVID-19) menimbulkan pengaruh yang serius pada tenaga kesehatan. Dampak yang paling berpengaruh yaitu kesehatan, dampak kesehatan yang ditimbulkan bukan hanya kesehatan secara fisik namun dapat memiliki efek serius pada kesehatan mental dan merujuk untuk munculnya keluhan stres kerja khususnya petugas kesehatan atau perawat. Kasus COVID-19 tidak bisa diprediksi, maka perlu adanya perkembangan ilmu kesehatan dalam penanganan COVID-19 khususnya pada perawat. Penelitian ini bertujuan untuk mengetahui Hubungan antara Beban Kerja dengan Stres Kerja pada Perawat Pelaksana di Ruang Isolasi COVID-19 Rumah Sakit Umum Daerah Kota Kotamobagu. Jenis penelitian kuantitatif dengan menggunakan metode analitik observasional dengan pendekatan studi potong lintang Cross-Sectional, dilaksanakan di RSUD Kota Kotamobagu pada bulan Agustus - Oktober tahun 2021. Sampel sebanyak 62 responden dengan menggunakan teknik pengambilan sampel yaitu total sampling. Instrumen dalam penelitian ini menggunakan kuesioner. Penelitian ini di ikuti oleh 62 responden dimana 53% berumur  28 tahun, mayoritas perempuan 71,6% dengan tingkat pendidikan D3 69,4% dan masa kerja  5 tahun 74%. Pada penelitian ini ditemukan 91,9% melaporkan mengalami stres ringan dan mempunyai beban kerja ringan 75,8%. Hasil penelitian ini menggunakan uji korelasi Somers’d. Hasil yang didapatkan dalam penelitian ini yaitu berdasarkan uji statistik diperoleh nilai korelasi koefisien sebesar 0,157 yang menunjukkan korelasi yang sangat lemah dengan nilai p = 0.153>0,05 artinya tidak ada hubungan antara beban kerja dengan stres kerja pada perawat pelaksana di ruang isolasi COVID-19 RSUD Kota Kotamobagu. Kesimpulan dalam penelitian ini bahwa beban kerja bukan satu-satunya faktor penting yang mempengaruhi stres kerja pada perawat pelaksana diruang isolasi COVID-19 RSUD Kota Kotamobagu. Saran untuk instansi rumah sakit agar bisa mengevaluasi faktor-faktor lain yang bisa menyebabkan stres pada perawat. Kata kunci: stres kerja, beban kerja, perawat pelaksana ruang isolasi COVID-19 ABSTRACTThe impact of the Coronavirus Disease of 2019 (COVID-19) outbreak has a serious impact on health workers. The most influential impact is health, the health impact caused not only physical health but can have a serious effect on mental health and refer to the emergence of complaints of work stress, especially health workers or nurses. COVID-19 cases cannot be predicted, so there needs to be the development of health science in handling COVID-19, especially in nurses. This study aims to find out the relationship between workload and work stress in the managing nurse in the isolation room of COVID-19 kotamobagu regional general hospital. This type of quantitative research using observational analytical methods with cross-sectional latitude cut study approach, was carried out at Kotamobagu Hospital in August - October 2021. A sample of 62 respondents using sampling techniques, namely total sampling. The instruments in the study used questionnaires. The study was followed by 62 respondents where 53% aged ≤ 28 years, the majority of women 71.6% with a D3 education level of 69.4% and a working period of ≤ 5 years 74%. In this study, 91.9% reported experiencing mild stress and having a light workload of 75.8%. The results of this study used the Somers'd correlation test. The results obtained in this study, based on statistical tests obtained a coefficient correlation value of 0.157 which showed a very weak correlation with a value of p = 0.153>0.05 means that there is no relationship between workload and work stress in the implementing nurse in the isolation room of COVID-19 Kotamobagu Hospital. The conclusion in this study that workload is not the only important factor that affects work stress in the implementing nurses in the isolation room of COVID-19 Kota Kotamobagu Hospital. Advice for hospital agencies to be able to evaluate other factors that can cause stress in nurses. Keywords: work stress, workload, COVID-19 isolation room managing nurse  

In Search of Magnetic Properties of Samarium Cobalt (Sm2Co17) within a Low-Temperature Sintering Process

Samarium cobalt is known as super high density magnetic material with large magnetic anisotropy energy. Samarium–cobalt exhibits manipulative magnetic properties as a rare-earth material which has different properties in a low sintering temperature. It is therefore of paramount importance to investigate samarium cobalt (Sm2Co17) magnetic properties in the low temperature sintering condition. Sm2Co17, which is utilized in this research, is synthesized via the sol–gel process at sintering temperatures of 400, 500, and 600 °C. Subsequently, the crystallites indicate the formation of a single-phase Sm2Co17 on all the samples in all temperature variations. Moreover, the peaks in the X-ray diffraction analysis of crystallite sizes calculated using the Scherrer equation are 17.730, 15.197, and 13.296 nm at 400, 500, and 600 °C. Through scanning electron microscopy, the particles are found to be relatively large and agglomerated, with average sizes of 143.65, 168.78, and 237.26 nm. The functional groups are also analyzed via Fourier-transform infrared spectroscopy, which results in the appearance of several bonds in the samples, for example, alkyl halides, alkanes, and esters with aromatic functional groups on the fingerprint area and alkynes, alkyl halides, and alcohol functional groups at a wavelength of above 1500 cm. The test results of the magnetic properties using vibrating-sample magnetometer (VSM) revealed high coercivity and retentivity in the samples sintered at 400 °C. However, the highest saturation occurs in the samples sintered at 600 ℃. At a low sintering temperature (below 1000 °C), samarium cobalt shows as the soft magnetic material. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Variabilidade de pigmentos diagnósticos da comunidade fitoplanctônica no Canal de São Sebastião (São Paulo-BR)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Núcleo de Pesquisa em Biodiversidade Marinha da Universidade de São Paulo (NP-BioMar/USP

Protocol for a randomised controlled trial to evaluate the effectiveness of improving tuberculosis patients’ treatment adherence via electronic monitors and an app versus usual care in Tibet

Background Treatment non-adherence is a serious challenge to effective tuberculosis (TB) control in Tibet. In this study we will pilot and evaluate the effectiveness of using new electronic monitors (e-monitors) and a smartphone app to improve treatment adherence among new pulmonary TB patients in Tibet. Methods We will use a multicentre, parallel-group, individually randomised controlled, superiority trial with blinded outcome evaluation and unblinded treatment. We will randomise new pulmonary TB outpatients (aged ≥ 15 years old and free from communication impairment) from Shigatse, Tibet to either the intervention or control arm in a 1:1 ratio at the time of their diagnosis. All patients will be treated according to the World Health Organisation standard 6-month TB treatment regimen and the China National TB programme guidelines. Intervention arm patients will be given their medication via e-monitors that have automatic voice reminders, and record medication adherence data and share it with health staff via Cloud connection. Intervention patients will also be encouraged to receive smartphone-based video-observed treatment if their adherence is problematic. Control arm patients will receive their medication in e-monitors that will collect medication adherence history, but will have their reminder function deactivated and are not linked to the app. The primary outcome is the rate of poor adherence, measured monthly during treatment as a binary indicator where poor adherence means missing ≥ 20% of doses in a month. We will conduct a qualitative process evaluation to explore operational questions regarding acceptability, cultural appropriateness and burden of technology use, as well as a cost-effectiveness analysis and an analysis of the long-term effects of the intervention on TB control. Discussion Our study is one of the first trials to evaluate the use of e-monitors and smartphone apps for customised treatment support in low- and middle-income countries (LMICs). All intervention activities are designed to be embedded into routine TB care with strong local ownership. Through the trial we intend to understand the feasibility of our intervention, its effectiveness, its cost-effectiveness and its long-term impacts to inform future scale-up in remote areas of China and other LMICs. Trial registration Current Controlled Trials, ID: ISRCTN52132803. Registered on 9 November 2018

Advanced interface models for metal forming simulations

Friction and heat transfer in metal forming simulations are usually restricted by software to be interface constants, a situation not reflected by the mechanics of real manufacturing processes. A better simulation approach is to use a micromechanics based method to estimate friction and heat transfer as evolutionary phenomenon. This paper presents a friction and heat transfer module for hot forging simulations. The friction model is based on a lubricant film thickness calculation using the Reynolds equation, and a calculation of the fractional contact area based on asperity flattening and roughening. Friction is then portioned between asperity and lubricant contacts. Heat transfer coefficients are calculated using a new model for heat conduction through asperity contact patches and lubricant that takes into account the restriction to heat flow at the contacts. The program is implemented as a user routine in a popular commercially available finite element code, DEFORM 2D.Schmid, SR.; Liu, J.; Sellés Cantó, MÁ.; Pasang, T. (2013). Advanced interface models for metal forming simulations. Computational Materials Science. 79:763-771. doi:10.1016/j.commatsci.2013.07.025S7637717

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Drillability of Titanium Alloy 6246 from Surface Quality Perspective

Drillablity derived from term of machinability, which is applied in drilling. In this study, drillability of titanium alloy 6246 has been investigated through observation of two responses of drilled holes quality, i.e. surface roughness and holes roundness. Taguchi L18 Design Experiment-based approach was used to gain an optimum setting of five drilling parameters: coolant, heat treatment variation, depth of drilling, cutting speed and feed rate. The tool used was TiAlN coated carbide drill insert. Minitab 17 was employed for processing the data; analysis of S/N ratio to find effect of each parameter and ANOVA were employed for analysing the significant of each parameter to the surface quality respectively. ANOVA shows that depth of drilling contributes 55% to the roughness, followed by heat treatment (25%), while coolant only affects the roughness quality by 2%. All the 5 parameters chosen in this research has no statistically significant effect to the roundness. The predicted optimum value of surface roughness of between 0.591 µm to 0.803 µm would be achieved when drilling Ti-6246 at a maximum depth of 10 mm, without coolant, cutting speed of 35 m/min and feed rate of 0.08 mm/min on the as received block.</jats:p