Bayesian Probabilistic Power Flow Analysis Using Jacobian Approximate Bayesian Computation

A probabilistic power flow (PPF) study is an essential tool for the analysis and planning of a power system when specific variables are considered as random variables with particular probability distributions. The most widely used method for solving the PPF problem is Monte Carlo simulation (MCS). Although MCS is accurate for obtaining the uncertainty of the state variables, it is also computationally expensive, since it relies on repetitive deterministic power flow solutions. In this paper, we introduce a different perspective for the PPF problem. We frame the PPF as a probabilistic inference problem, and instead of repetitively solving optimization problems, we use Bayesian inference for computing posterior distributions over state variables. Additionally, we provide a likelihood-free method based on the Approximate Bayesian Computation philosophy, that incorporates the Jacobian computed from the power flow equations. Results in three different test systems show that the proposed methodologies are competitive alternatives for solving the PPF problem, and in some cases, they allow for reduction in computation time when compared to MCS

Effect of Reprocessing and Excipient Characteristics on Ibuprofen Tablet Properties

Purpose: To determine excipient and ibuprofen:excipient mixture sensitivity to reprocessing produced by either direct compression or wet granulation.Methods: The effect of excipient type, technology and reprocessing on flow, compressibility and compactibility was assessed using and 8x2x2 factorial design. Design Expert® v.8.01 software was employed for data analysis. Pure excipients were processed by direct compression, while the ibuprofen:excipient mixtures were processed by wet granulation. Once compacts were produced, they were milled and reprocessed using the same technologies, respectively. Excipient properties such as particle size, porosity and densities were also evaluated.Results: For most excipients, reprocessing caused a 20 – 50 % decrease in particle size and 5 – 80 % reduction in porosity, but increased compactibility (10 – 50 %). Flow decreased (30 – 50 %) only for highly densified excipients such as calcium carbonate and calcium diphosphate.Conclusion: Microcrystalline cellulose and sorbitol are the excipients with the best tableting properties when reprocessing is conducted via wet granulation and direct compression platforms, respectively.Keywords: Reprocessing, Excipient, Microcrystalline Cellulose, Sorbitol Direct Compression, Wet Granulation, Ibuprofe

Descripción de la flora causante de candidemia en pacientes adultos críticamente enfermos y determinación de los factores de riesgo relacionados en las unidades de cuidado intensivo del Hospital Militar Central en los años 2006 a 2011

El presente proyecto de investigación busca describir la distribución epidemiológica de las diferentes especies de Cándida spp, causantes de candidemia en los pacientes adultos ingresados a las Unidades de Cuidado Intensivo del Hospital Militar Central durante los años 2006 a 2011. Se trata de una investigación de diseño descriptivo analítico retrospectivo a realizarse mediante la revisión y recolección de datos de las historias clínicas de los pacientes con hemocultivos positivos para cándida de acuerdo con los registros de la sección de Microbiología del Laboratorio Clínico del HM

The mysterious extravillous trophoblast

Extravilluos Trophoblast (EVT) is a truly special cell. It has a temporary character and tumor-like behavior and tumor-like appearance, all of which seem to belong to the malignancy fi eld [1,2]. It is also known as intermediate trophoblast, derived from cytotrophoblast [3-5], having formed between the latter and the syncytiotrophoblast. EVT is capable of reaching the decidua through trophoblast cell columns that connect the anchoring villi to the basal plate in early gestation.https://orcid.org/0000-0002-7147-425Xhttps://orcid.org/0000-0002-0446-0042Revista Internacional - No indexadaN

El estudio arqueométrico de la producciones cerámicas

El estudio de la pasta de las cerámicas mediante lámina delgada, difracción de rayos X y su análisis quimico permite profundizar en el conocimiento sobre el origen de las mismas y en su tecnología de elaboración, asi como determinar las temperaturas minimas o maximas de cocción alcanzadas. De igual modo permite poner de manifiesto las modificaciones posteriores sufridas por el uso continuado de las mismas y por procesos tardíos debidos al soterramiento de las piezas. Los resultados obtenidos cotejados con la informacion arqueológica, la contextualización de los yacimientos y el entorno cultural de cada época permite constatar en algunos casos pautas comerciales o de intercambi

Copositive certificates of non-negativity for polynomials on semialgebraic sets

A certificate of non-negativity is a way to write a given function so that its non-negativity becomes evident. Certificates of non-negativity are fundamental tools in optimization, and they underlie powerful algorithmic techniques for various types of optimization problems. We propose certificates of non-negativity of polynomials based on copositive polynomials. The certificates we obtain are valid for generic semialgebraic sets and have a fixed small degree, while commonly used sums-of-squares (SOS) certificates are guaranteed to be valid only for compact semialgebraic sets and could have large degree. Optimization over the cone of copositive polynomials is not tractable, but this cone has been well studied. The main benefit of our copositive certificates of non-negativity is their ability to translate results known exclusively for copositive polynomials to more general semialgebraic sets. In particular, we show how to use copositive polynomials to construct structured (e.g., sparse) certificates of non-negativity, even for unstructured semialgebraic sets. Last but not least, copositive certificates can be used to obtain not only hierarchies of tractable lower bounds, but also hierarchies of tractable upper bounds for polynomial optimization problems.Comment: 27 pages, 1 figur