New Method to Predict the Viscosity of Bitumen Diluted with Light Oil Using a Modified Van Der Wijk Model under Reservoir Temperature and Pressure.

In this study, we introduce a new method for the prediction of the viscosity of bitumen diluted with light oil under reservoir temperature and pressure. This two-step method works as follows: first, predicting the bitumen viscosity under reservoir temperature and pressure using the classical Mehrotra and Svrcek model, and then subsequently using it in the modified Van Der Wijk (MVDM) model. This model formed from the modification of the original Van Der Wijk model was developed from the consideration of the interactions between like molecules in different binary components of the mixture. In this study, the bitumen viscosity was predicted with an average absolute deviation percentage (AAD%) of 3.86. The accuracy of the MVDM was investigated from the experimental results obtained from the rheological studies of three binary mixtures of light oil (API 32°) and bitumen (API 7.39°). Dead oils were mixed on a mass fraction basis. The viscosity was measured at a temperature range of 45-110 °C and a pressure range of 0.1-6 MPa. For comparison purposes, a reworked Van Der Wijk model (RVDM) was used in the same method and compared to the MVDM. The latter was more accurate than the RVDM with AAD% values of 8.88, 8.02, and 5.07 in predicting the viscosity of the three mixtures of 25, 32.5, and 50% bitumen with light oil. On the other hand, the RVDM had AAD% values of 12.42, 11.43, and 7.87 for the same mixtures, respectively. The applicability of this method was further verified by comparing its accuracy to another reported method using published data and it was found that the MVDM had AAD% values of 1.86, 6.55, and 2.823 when predicting the viscosities of the three mixtures under reservoir temperature and pressure conditions.

Diagnóstico por imagem na cardiomiopatia hipertrófica: Comparação entre os métodos / Diagnostic imaging in hypertrophic cardiomyopathy: comparison between methods

A cardiomiopatia hipertrófica consiste na doença cardíaca genética de maior prevalência, com transmissão autossômica dominante, caracterizada por hipertrofia miocárdica, sem que haja outra doenças sistêmica ou cardíaca para justificá-la. Apresenta amplo espectro clínico e prognóstico variável, desde um quadro estável e benigno até a fase terminal de insuficiência cardíaca e morte súbita, particularmente em indivíduos jovens. Neste contexto, é essencial o diagnóstico precoce da doenças e a estratificação de risco de morte súbita. Já que as manifestações clínicas e os padrões eletrocardiográficos são variáveis e inespecíficos, o diagnóstico por imagem é fundamental , até para o entendimento dos mecanismos fisiopatológicos. Diversos métodos de imagem podem ser utilizados para avaliar a estrutura e a função cardíacas, a presença e a quantificação de obstrução intraventricular, anormalidades na valva mitral, isquemia miocárdica, além de identificação de áreas com fibrose...