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Math-based models developed by the MSU/CAVS team have considered both the compaction and sintering processes. Due to the very large number of input variables for the compaction model it is helpful to understand how sensitive the model output is to small changes in these input variables in order to better apply the model to real world processes. Using numerical methods both uncertainty and sensitivity analysis can be applied to the model and the most significant terms identified. Through further numerical analysis the output of the compaction model can be optimized for one or more output parameters, e.g. least density variation, lowest mass, minimal part thickness. These techniques will be illustrated using a well-established automotive PM product, the main bearing cap., var.pagings;Metal Powder Industries Federation (MPIF)

In an earlier study, the authors presented a characterisation of the FC-0205 Ancorsteel powders containing 0.6 and 1.0% Acrawax to define the evolution of the failure line and cap surface of the modified Drucker/Prager cap model during compaction. Using the results of that study (i.e. FC-0205 material parameters), this paper presents sensitivity and uncertainty analysis of the microstructure-property relationships for powder metallurgy compaction. It is found for all of the responses of interest (the compressibility curve, the interparticle friction, the material cohesion, the cap eccentricity and the elastic modulus) that the most dominant parameter is the initial (or tap) density. It is also observed that the uncertainty in output parameters for the case of 1% wax is much larger than those for the case of 0.6% wax, due to the large uncertainty in the failure stress (in particular, the compressive failure stress).

Math-based models developed by the MSU/CAVS team have considered both the compaction and sintering processes. Due to the very large number of input variables for the compaction model it is helpful to understand how sensitive the model output is to small changes in these input variables in order to better apply the model to real world processes. Using numerical methods both uncertainty and sensitivity analysis can be applied to the model and the most significant terms identified. Through further numerical analysis the output of the compaction model can be optimized for one or more output parameters, e.g. least density variation, lowest mass, minimal part thickness. These techniques will be illustrated using a well-established automotive PM product, the main bearing cap., var.pagings;Metal Powder Industries Federation (MPIF)

In an earlier study, the authors presented a characterisation of the FC-0205 Ancorsteel powders containing 0.6 and 1.0% Acrawax to define the evolution of the failure line and cap surface of the modified Drucker/Prager cap model during compaction. Using the results of that study (i.e. FC-0205 material parameters), this paper presents sensitivity and uncertainty analysis of the microstructure-property relationships for powder metallurgy compaction. It is found for all of the responses of interest (the compressibility curve, the interparticle friction, the material cohesion, the cap eccentricity and the elastic modulus) that the most dominant parameter is the initial (or tap) density. It is also observed that the uncertainty in output parameters for the case of 1% wax is much larger than those for the case of 0.6% wax, due to the large uncertainty in the failure stress (in particular, the compressive failure stress).

Background: Most patients with idiopathic nephrotic syndrome (NS) are steroid-responsive, about 50% relapse and often become steroid-dependent. The aim of this study was to determine epidemiology, treatment and outcome of children with first episode of NS. Methods: This was a retrospective hospital-based cohort study in the department of pediatric nephrology of Charles Nicolle, Tunis, between 2002 and 2012. It included 52 children with idiopathic NS aged from 1 to 12 years, hospitalized for the first manifestation of the NS and followed for at least one year. Results: The median age of presentation was 5.1±2.5 years. Male to female ratio was 2.7:1. Family history of atopy was found in 14 (26.9%) patients and personal atopy was noted in 9 (17.3%) patients. Microscopic hematuria was seen in 33 (63.5%) patients. The mean blood level of albumin was 1.17±4.2 g/dl, alpha-2 globulin was 1.71±3.5g/dl, cholesterol was 413.7±2.4 mg/dl and the mean proteinuria was 148±70 mg/kg/day. The mean time for first remission was 15.8±2 days. Thirty-eight patients (73%) relapsed and 31 patients (59.6%) became steroid dependent. Total 32 (61.5%) patients recovered from their NS with average interval between the onset of illness and recovery being 3.8±2.1 years (range: 2-10 years). Twenty-two (42.3%) required immunosuppressive drugs such as cyclophosphamide, mycophenolate mofetil and cyclosporine. Thirty-two patients (61.5%) were in remission and off therapy for more than 2 years. The most frequents adverse effects of steroid treatment were growth failure in 22 (42.3%) and osteoporosis in 7 (21.8%) patients. Renal functions remained normal for all patients. Conclusion: The prognosis of idiopathic NS is good but the risk of progression to steroid dependence is high, which exposes these children to complications of long-term corticosteroid therapy. Prospective trials are necessary to identify effective and safe therapies for patients with frequent relapses and steroid dependence.