El concepto de paradigma en la Archivística como problema epistemológico

Se plantea la discusión sobre la cientificidad de la Archivística desde la perspectiva kuhniana. Se realiza una reseña histórica de la disciplina, mencionando sus principales logros teóricos. Se analizan diversos intentos propuestos por autores para dotar de fundamentos epistemológicos al área. Las posturas estudiadas para este análisis son aquellas que proponen un enfoque desde la perspectiva de Thomas Kuhn. Se observa en la literatura el uso del concepto paradigma como modelo de análisis para el fundamento epistemológico de la disciplina. Se analizan las problemáticas surgidas a partir su introducción, notando que con su aplicación se incurre en una mudanza de niveles de análisis epistémicos. Como consecuencia, resulta dificultoso esclarecer las pretensiones de cientificidad de la Archivística. Se presenta como primera interrogante la posibilidad de articular el desarrollo histórico de la Archivística con la existencia de paradigmas; y en segundo término se plantea si los paradigmas identificados en la literatura pueden ser considerados como tales, o si se trata de teorías que han adquirido cierto grado de organización. Se afirma que la cientificidad y madurez disciplinar se determina mediante la asunción de una tradición exitosa de resolución de problemas, ya que los intentos exitosos terminan consolidando el campo de investigación.

El concepto de paradigma en la Archivística como problema epistemológico

Se plantea la discusión sobre la cientificidad de la Archivística desde la perspectiva kuhniana. Se realiza una reseña histórica de la disciplina, mencionando sus principales logros teóricos. Se analizan diversos intentos propuestos por autores para dotar de fundamentos epistemológicos al área. Las posturas estudiadas para este análisis son aquellas que proponen un enfoque desde la perspectiva de Thomas Kuhn. Se observa en la literatura el uso del concepto paradigma como modelo de análisis para el fundamento epistemológico de la disciplina. Se analizan las problemáticas surgidas a partir su introducción, notando que con su aplicación se incurre en una mudanza de niveles de análisis epistémicos. Como consecuencia, resulta dificultoso esclarecer las pretensiones de cientificidad de la Archivística. Se presenta como primera interrogante la posibilidad de articular el desarrollo histórico de la Archivística con la existencia de paradigmas; y en segundo término se plantea si los paradigmas identificados en la literatura pueden ser considerados como tales, o si se trata de teorías que han adquirido cierto grado de organización. Se afirma que la cientificidad y madurez disciplinar se determina mediante la asunción de una tradición exitosa de resolución de problemas, ya que los intentos exitosos terminan consolidando el campo de investigación.

El concepto de paradigma en la Archivística como problema epistemológico

Se plantea la discusión sobre la cientificidad de la Archivística desde la perspectiva kuhniana. Se realiza una reseña histórica de la disciplina, mencionando sus principales logros teóricos. Se analizan diversos intentos propuestos por autores para dotar de fundamentos epistemológicos al área. Las posturas estudiadas para este análisis son aquellas que proponen un enfoque desde la perspectiva de Thomas Kuhn. Se observa en la literatura el uso del concepto paradigma como modelo de análisis para el fundamento epistemológico de la disciplina. Se analizan las problemáticas surgidas a partir su introducción, notando que con su aplicación se incurre en una mudanza de niveles de análisis epistémicos. Como consecuencia, resulta dificultoso esclarecer las pretensiones de cientificidad de la Archivística. Se presenta como primera interrogante la posibilidad de articular el desarrollo histórico de la Archivística con la existencia de paradigmas; y en segundo término se plantea si los paradigmas identificados en la literatura pueden ser considerados como tales, o si se trata de teorías que han adquirido cierto grado de organización. Se afirma que la cientificidad y madurez disciplinar se determina mediante la asunción de una tradición exitosa de resolución de problemas, ya que los intentos exitosos terminan consolidando el campo de investigación.

El concepto de paradigma en la Archivística como problema epistemológico

Se plantea la discusión sobre la cientificidad de la Archivística desde la perspectiva kuhniana. Se realiza una reseña histórica de la disciplina, mencionando sus principales logros teóricos. Se analizan diversos intentos propuestos por autores para dotar de fundamentos epistemológicos al área. Las posturas estudiadas para este análisis son aquellas que proponen un enfoque desde la perspectiva de Thomas Kuhn. Se observa en la literatura el uso del concepto paradigma como modelo de análisis para el fundamento epistemológico de la disciplina. Se analizan las problemáticas surgidas a partir su introducción, notando que con su aplicación se incurre en una mudanza de niveles de análisis epistémicos. Como consecuencia, resulta dificultoso esclarecer las pretensiones de cientificidad de la Archivística. Se presenta como primera interrogante la posibilidad de articular el desarrollo histórico de la Archivística con la existencia de paradigmas; y en segundo término se plantea si los paradigmas identificados en la literatura pueden ser considerados como tales, o si se trata de teorías que han adquirido cierto grado de organización. Se afirma que la cientificidad y madurez disciplinar se determina mediante la asunción de una tradición exitosa de resolución de problemas, ya que los intentos exitosos terminan consolidando el campo de investigación.

The study of ternary carbides formation during SPS consolidation process in the WC-Co-steel system

Tungsten carbide has a wide range of applications, mainly cemented carbides made of WC and Co, as wear resistant materials. However, the high cost of WC-Co powders encourages the use of a substrate to manufacture a functionally graded material (FGM) tool made of WC-Co and a tool steel. These materials join the high wear resistance of the cemented carbide and the toughness of the steel. This work deals with the study interaction of the WC-Co and H13 steel to design a functionally graded material by means of spark plasma sintering (SPS). The SPS, a novel sintering technique reaching the consolidation of the powders at relatively low temperatures and short dwell times, is a promising technique in processing materials. In this study, WC, H13 steel, WC-Co, WC-H13 steel and WC-Co-H13 steel bulk samples were investigated using scanning electron microscopy and X-ray diffraction techniques to evaluate the phase transformations involved during SPS consolidation process. The W(2)C and W(3)Fe(3)C precipitation were identified after the SPS consolidation of the WC and WC-H13 steel samples, respectively. The precipitation Of W(4)Co(2)C was also identified in the WC-Co and WC-Co-H13 steel samples. The WC-H 13 steel and WC-Co-H13 steel were also evaluated after heat treatments at 1100 degrees C for 9 h, which enhanced the chemical interaction and the precipitation of W(3)Fe(3)C and W(4)Co(2)C, respectively. (C) 2009 Elsevier Ltd. All rights reserved.

Recycling of silicon carbide and corn starch as binder originating from commercial starch consolidation

The main goal of this work is to demonstrate that the use of recycled material originated from SiC ceramics is viable. These ceramics were produced by commercial starch consolidation process. Before calcination stage, surplus of these materials always appears. This surplus is rich in SiC and starch. Samples were made by material previously milled in automatic mortar and sieved (100 Tyler). Later, 10% of distilled water was added to the material and the mixture was pressed at 40 MPa. In order to characterize the ceramic, three point flexural test were made, according to the ASTM C1161/94 norm. The results were analyzed by Weibull statistical method. Apparent density and porosity measures also were made, according to ASTM C20/87 norm. A verification of the surface was made in the fracture area by the depth from focus method and SEM image analysis. The results showed that the recycling process is fully viable, being a good economic option and reduce possible pollutant effect to the environment.

Microstructure of ceramics TiO2 obtained by protein consolidation

Porous ceramics can be produced by adding starch (corn, potato) and protein (animal or vegetable) to raw material as pore forming element. In this study, titanium dioxide ceramics were formed by vegetable protein consolidation. Soybean was chosen as the binding agent and pore forming. The samples, which were produced in cylindrical shape, had the following processing: material mixture, gelling, drying, pre-sintering and sintering. Heated platinum microscopy were performed by using suspensions with different compositions in order to verify protein gelling capacity and better know the temperature in which this process occurs. The samples were characterized by apparent porosity and roughness measurement. Besides, imaging by light microscopy was also performed in order to determine the sample morphology and porosity. © (2012) Trans Tech Publications, Switzerland.

Index properties, shear strenghts and consolidation characteristics of ODP Hole 164-995A sediments

Geotechnical properties of sediment from Ocean Drilling Program Leg 164 are presented as: (1) normalized shipboard strength ratios from the Cape Fear Diapir, the Blake Ridge Diapir, and the Blake Ridge; and (2) Atterberg limit, vane shear strength, pocket-penetrometer strength, and constant-rate-of-strain consolidation results from Hole 995A, located on the Blake Ridge. This study was conducted to understand the stress history in a region characterized by high sedimentation rates and the presence of gas hydrates. Collectively, the results indicate that sediment from the Blake Ridge exhibits significant underconsolidated behavior, except near the seafloor. At least 10 m of additional overburden was removed by erosion or mass wasting at Hole 993A on the Cape Fear Diapir, compared to nearby sites.

Consolidation properties and strength characteristics of ODP Site 204-1244 sediments

Eight whole-core samples from Ocean Drilling Program Site 1244, Hydrate Ridge, Cascadia continental margin, were provided to Massachusetts Institute of Technology (Cambridge, Massachusetts, USA) for geotechnical characterization. The samples were collected from depths ranging from 5 to 136 meters below seafloor (mbsf). Seven of the eight whole-core samples were located within the gas hydrate stability zone, whereas the eighth sample was located in the free gas zone. Atterberg limits testing showed that the average liquid limit of the soil is 81% and the average plastic limit is 38%, giving an average plasticity index of 43%. The liquid limit is sensitive to oven drying, shown by a drop in liquid limit to 64% when tests were performed on an oven-dried sample. Loss on ignition averages 5.45 wt%. Constant rate of strain consolidation (CRSC) tests were performed to obtain the compression characteristics of the soil, as well as to determine the stress history of the site. CRSC tests also provided hydraulic conductivity and coefficient of consolidation characteristics for these sediments. The compression ratio (Cc) ranges from 0.340 to 0.704 (average = 0.568). Cc is fairly constant to a depth of 79 mbsf, after which Cc decreases downhole. The recompression ratio (Cr) ranges from 0.035 to 0.064 (average = 0.052). Cr is constant throughout the depth range. In situ hydraulic conductivity varies between 1.5 x 10**-7 and 3 x 10**-8 cm/s and shows no trend with depth. Ko-consolidated undrained compression/extension (CKoUC/E) tests were also performed to determine the peak undrained shear strength, stress-strain curve, and friction angle. The normalized undrained strength ranges from 0.29 to 0.35. The friction angle ranges from 27 to 37. Because of the limited amount of soil, CRSC and CKoUC/E tests were also conducted on resedimented specimens.

Consolidation and strength assessment of ODP Leg 123 sediments

Twenty-one samples, ranging in depth from 0 to 150 meters below seafloor (mbsf), were obtained from Leg 123 Sites 765 and 766. All samples were tested for Atterberg limits: 14 for laboratory vane shear strength and seven for uniaxial consolidation. Based on the determined Atterberg limits, along with shipboard measurements of water content, the sediment appears to be underconsolidated from 0 to 40 mbsf at Site 765 and from 0 to 80 mbsf at Site 766. Normal consolidation trends were observed for the sediments below these depths. Vane shear strengths, when compared with calculated values for a normally consolidated clay, indicate underconsolidated sediment at both sites. However, the use of Atterberg limit and vane shear strength data to assess consolidation state is complicated by the presence of silt-sized calcium carbonate in the form of nannofossil ooze. Thus, uniaxial-consolidation test data were analyzed to determine the overconsolidation ratios (OCR) and sediment compressibilities. OCR values were found to be less than one (underconsolidated) at both sites, using two separate methods of analysis.

Physical properties, compressional-wave velocity and consolidation characteristics of ODP Holes 133-815B and 133-817B

Sites 815 and 817 were drilled near the Townsville Trough during Leg 133 of the Ocean Drilling Program. The physical properties, compressional-wave velocity, and consolidation characteristics indicate that the periplatform carbonate sediments maintain more water content and lower compressional velocity near the Queensland Plateau than the clayey hemipelagic sediments, which have a clay content of up to 60%. Bulk density, void ratio or porosity, water content, and compressional-wave velocity are shown to have a linear relationship with burial depth. Between 3.5 and 5 Ma (about 100-500 mbsf), these physical properties maintained a constant rate vs. the depth in core because of the fast sedimentation-rate effect at Site 815. However, compressionalwave velocity still increases downward in this section. The clay content in this section causes an increase of bulk modulus and compaction effect. At Site 817, scarce terrigenous mud content and abundant carbonate content (88%-97%) cause a straight line relationship between physical properties and burial depth. During the consolidation test, we show that dominant micritic particles may cause faster acoustic velocity than sediments composed mainly of coccoliths. The bulk modulus ratio increasing rate in the clay-rich carbonate sediments is almost 4.5 times higher than in the clay-free periplatform carbonate sediments.

Consolidation properties and hydraulic conductivities of sediments from ODP Leg 207 sites

The stress history, permeability, and compressibility of sediments from Demerara Rise recovered during Ocean Drilling Program Leg 207 were determined using one-dimensional incremental load consolidation and low-gradient flow pump permeability tests. Relationships among void ratio, effective stress, and hydraulic conductivity are presented for sampled lithologic units and used to reconstruct effective stress, permeability, and in situ void ratio profiles for a transect of three sites across Demerara Rise. Results confirm that a significant erosional event occurred on the northeastern flank of the rise during the late Miocene, resulting in the removal of ~220 m of upper Oligocene-Miocene deposits. Although Neogene and Paleogene sediments tend to be overconsolidated, Cretaceous sediments are normally consolidated to underconsolidated, suggesting the presence of overpressure. A pronounced drop in permeability occurs at the transition from the Cretaceous black shales into the overlying Maastrichtian-upper Paleocene chalks and clays. The development of a hydraulic seal at this boundary may be responsible for overpressure in the Cretaceous deposits, leading to the lower overconsolidation ratios of these sediments. Coupled with large regional variations in sediment thickness (overburden stresses), the higher permeability overpressured Cretaceous sediments represent a regional lateral fluid conduit on Demerara Rise, possibly venting methane-rich fluids where it outcrops on the margin's northeastern flank.