Preliminary Design of a Calorimeter for Experimental Determination of Effective Absorptivity of Metal Substrates During Laser Powder Deposition

2005 ◽  
Author(s):  
Jacob J. Koester ◽  
Michael A. Langerman ◽  
Umesh A. Korde ◽  
James W. Sears ◽  
Gregory A. Buck
Keyword(s):  
Experimental Data ◽  
Thermal Model ◽  
Laser Energy ◽  
Metal Substrate ◽  
Published Data ◽  
Preliminary Design ◽  
Laser Powder Deposition ◽  
Powder Deposition ◽  
Laser Energy Absorption

A thermal model of the laser powder deposition (LPD) process has been developed and tested. Results obtained from the model, however, are dependent upon the magnitude of the laser energy absorbed during the process. Although spectral absorptivities of metal surfaces are described in literature, during the LPD process, the powder increases the energy delivered to the substrate. There are no published data regarding this affect. Therefore, the SDSM&T Additive Manufacturing Laboratory (AML) is developing a calorimeter to experimentally investigate the affect of the powder on laser energy absorption at the metal substrate. The preliminary design is described in this paper with discussion on measures being taken to increase the accuracy of experimental data.

Thermal Control of Laser Powder Deposition: Heat Transfer Considerations

2004 ◽  
Author(s):  
Michael A. Langerman ◽  
Gregory A. Buck ◽  
Umesh A. Korde ◽  
Vojislav D. Kalanovic
Keyword(s):  
Computer Aided Design ◽  
Thermal Model ◽  
Thermal Control ◽  
Free Form ◽  
Component Part ◽  
System Control ◽  
Forming Process ◽  
Laser Powder Deposition ◽  
Powder Deposition ◽  
Melt Pool Size

Laser based solid free-form fabrication is an emerging metallurgical forming process aimed at rapid production of high quality, near net shape products directly from starting powders. Laser powder deposition shares, with other free-form technologies, the common characteristic that part fabrication occurs directly from a 3-D computer aided design (CAD) model. The microstructure evolution and resulting material properties of the component part (strength, ductility, etc.) fabricated using laser deposition are dependent upon process operating parameters such as melt pool size, laser power, head (manipulator) speed, and powder flow rate. Presently, set points for these parameters are often determined through manual manipulation of the system control and trial and error. This paper discusses the development of a path-planning, feed-forward, process-driven control system algorithm that generates a component part thermal history within given constraints, thereby assuring optimal part quality and minimizing final residual stresses. A thermal model of the deposition process drives the control algorithm. The development of the thermal model is the subject of this paper. The model accounts for temperature-dependent properties and phase change processes. Model validation studies are presented including comparisons with known analytic solutions as well as comparisons with data from experiments conducted in the laser laboratory at SDSM&T.

Feedforward Laser Power Specification for Uniform Cooling of Thin-Walled Parts

2004 ◽  
Author(s):  
Umesh A. Korde ◽  
Michael A. Langerman ◽  
Gregory A. Buck ◽  
Vojislav D. Kalanovic
Keyword(s):  
Laser Power ◽  
Thermal Model ◽  
Deposition Process ◽  
Ongoing Research ◽  
Laser Powder Deposition ◽  
Powder Deposition ◽  
The Matrix ◽  
Thin Walled ◽  
The Time Domain ◽  
Power Sequence

This paper presents results from ongoing research on thermal-model based feedforward specification of laser power in a laser powder deposition process. The goal of this algorithm is to compute, before deposition of a layer, the laser power sequence and distribution that would produce a desired temperature distribution over that layer. This in turn will enable uniform cooling of the layer and avoid build up of residual stresses. In this paper, results based on a simplified thermal model and second-order spatial discretization are presented. Two types of discretization in the time domain are examined. The matrix-exponential-based discretization is expected to be more accurate at lower laser speeds. The desired laser power sequence and the resulting temperature histories for a prescribed laser speed are discussed within the context of a thin-walled part.

Equilibrium Sorptions in Heterogeneous Ion Exchange Membranes

1992 ◽  
Vol 57 (9) ◽  
pp. 1905-1914
Author(s):  
Miroslav Bleha ◽  
Věra Šumberová
Keyword(s):  
Experimental Data ◽  
Ion Exchange ◽  
Total Content ◽  
Distribution Coefficients ◽  
Exchange Capacity ◽  
Ion Exchange Membranes ◽  
Ion Exchange Capacity ◽  
Equilibrium Sorption ◽  
Inhomogeneity Factor

The equilibrium sorption of uni-univalent electrolytes (NaCl, KCl) in heterogeneous cation exchange membranes with various contents of the ion exchange component and in ion exchange membranes Ralex was investigated. Using experimental data which express the concentration dependence of equilibrium sorption, validity of the Donnan relation for the systems under investigation was tested and values of the Glueckauf inhomogeneity factor for Ralex membranes were determined. Determination of the equilibrium sorption allows the effect of the total content of internal water and of the ion-exchange capacity on the distribution coefficients of the electrolyte to be determined.

Numerical evaluation of hydrodynamic characteristics of planing hulls by using a hybrid method

2021 ◽  
pp. 147509022199024
Author(s):  
Emre Kahramanoglu ◽  
Silvia Pennino ◽  
Huseyin Yilmaz
Keyword(s):  
Experimental Data ◽  
Hybrid Method ◽  
Design Stage ◽  
Hydrodynamic Characteristics ◽  
Calm Water ◽  
Preliminary Design Stage ◽  
Reduction Function ◽  
Hull Forms ◽  
Good Agreement

The hydrodynamic characteristics of the planing hulls in particular at the planing regime are completely different from the conventional hull forms and the determination of these characteristics is more complicated. In the present study, calm water hydrodynamic characteristics of planing hulls are investigated using a hybrid method. The hybrid method combines the dynamic trim and sinkage from the Zarnick approach with the Savitsky method in order to calculate the total resistance of the planing hull. Since the obtained dynamic trim and sinkage values by using the original Zarnick approach are not in good agreement with experimental data, an improvement is applied to the hybrid method using a reduction function proposed by Garme. The numerical results obtained by the hybrid and improved hybrid method are compared with each other and available experimental data. The results indicate that the improved hybrid method gives better results compared to the hybrid method, especially for the dynamic trim and resistance. Although the results have some discrepancies with experimental data in terms of resistance, trim and sinkage, the improved hybrid method becomes appealing particularly for the preliminary design stage of the planing hulls.

scholarly journals Immunogenetic Predictors of Severe COVID-19

Vaccines ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 211
Author(s):  
Anna Malkova ◽  
Dmitriy Kudlay ◽  
Igor Kudryavtsev ◽  
Anna Starshinova ◽  
Piotr Yablonskiy ◽  
...  
Keyword(s):  
Genetic Factors ◽  
Virus Disease ◽  
Analysis Data ◽  
Published Data ◽  
Diagnostic Significance ◽  
Life Threatening ◽  
Coronavirus Infection ◽  
Angiotension Converting Enzyme ◽  
Related Proteins

According to an analysis of published data, only 20% of patients with the new coronavirus infection develop severe life-threatening complications. Currently, there are no known biomarkers, the determination of which before the onset of the disease would allow assessing the likelihood of its severe course. The purpose of this literature review was to analyze possible genetic factors characterizing the immune response to the new coronavirus infection that could be associated with the expression of angiotension-converting enzyme 2 (ACE-2) and related proteins as predictors of severe Corona virus disease 2019 (COVID-19). We analyzed original articles published in Medline, PubMed and Scopus databases from December 2019 to November 2020. For searching articles, we used the following keywords: New coronavirus infection, Severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2), COVID-19, severe course, complications, thrombosis, cytokine storm, ACE-2, biomarkers. In total, 3714 publications were selected using the keywords, of which 8 were in congruence with all the criteria. The literature analysis of the association of immunogenic characteristics and the expression of ACE-2 and related proteins with the development of severe COVID-19 revealed following genetic factors: HLA-B*46:01 genotype, CXCR6 gene hypoexpression, CCR9 gene expression, TLR7, rs150892504 mutations in the ERAP2 gene, overexpression of wild-type ACE-2, TMPRSS2 and its different polymorphisms. Genes, associated with the severe course, are more common among men. According to the analysis data, it can be assumed that there are population differences. However, the diagnostic significance of the markers described must be confirmed with additional clinical studies.

A Technique for the Laboratory Determination of Recirculation in Single Needle Dialysis

1993 ◽  
Vol 16 (2) ◽  
pp. 63-70 ◽  
Author(s):  
N.A. Hoenich ◽  
P.T. Smirthwaite ◽  
C. Woffindin ◽  
P. Lancaster ◽  
T.H. Frost ◽  
...  
Keyword(s):  
Experimental Data ◽  
Flow Rate ◽  
Experimental Results ◽  
New Technique ◽  
Treatment Efficiency ◽  
Single Lumen ◽  
Theoretical Predictions ◽  
Lumen Catheter ◽  
A New Technique

Recirculation is an important factor in single needle dialysis and, if high, can compromise treatment efficiency. To provide information regarding recirculation characteristics of access devices used in single needle dialysis, we have developed a new technique to characterise recirculation and have used this to measure the recirculation of a Terumo 15G fistula needle and a VasCath SC2300 single lumen catheter. The experimentally obtained results agreed well with those established clinically (8.5 ± 2.4% and 18.4 ± 3.4%). The experimental results have also demonstrated a dependence on access type, pump speeds and fistula flow rate. A comparison of experimental data with theoretical predictions showed that the latter exceeded those measured with the largest contribution being due to the experimental fistula.

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