Microfacies and sequence stratigraphy of the Amapa Formation, Late Paleocene to Early Eocene, Foz do Amazonas Basin, Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Microfacies and sequence stratigraphy of the Amapa Formation, Late Paleocene to Early Eocene, Foz do Amazonas Basin, Brazil

On the basis of thin-section studies of cuttings and a core from two wells in the Amapa Formation of the Foz do Amazonas Basin, five main microfacies have been recognized within three stratigraphic sequences deposited during the Late Paleocene to Early Eocene. The facies are: 1) Ranikothalia grainstone to packstone facies; 2) ooidal grainstone to packstone facies; 3) larger foraminiferal and red algal grainstone to packstone facies; 4) Amphistegina and Helicostegina packstone facies; and 5) green algal and small benthic foraminiferal grainstone to packstone facies, divisible locally into a green algal and the miliolid foraminiferal subfacies and a green algal and small rotaliine foraminiferal subfacies. The lowermost sequence (Si) was deposited in the Late Paleocene-Early Eocene (biozone LF1, equivalent to P3-P6?) and includes rudaceous grainstones and packstones with large specimens of Ranikothalia bermudezi representative of the mid- and inner ramp. The intermediate and uppermost sequences (S2 and S3) display well-developed lowstand deposits formed at the end of the Late Paleocene (upper biozone LF1) and beginning of the Early Eocene (biozone LF2) on the inner ramp (larger foraminiferal and red algal grainstone to packstone facies), in lagoons (green algal and small benthic foraminiferal facies) and as shoals (ooidal facies) or banks (Amphistegina and Helicostegina facies). Depth and oceanic influence were the main controls on the distribution of these microfacies. Stratal stacking patterns evident within these sequences may well have been related to sea level changes postulated for the Late Paleocene and Early Eocene. During this time, the Amapa Formation was dominated by cyclic sedimentation on a gently sloping ramp. Environmental and ecological stress brought about by sea level change at the end of the biozone LF1 led to the extinction of the larger foraminifera (Ranikothalia bermudezi). (c) 2009 Elsevier B.V. All rights reserved.

INTERPOLATING BLASCHKE PRODUCTS AND ANGULAR DERIVATIVES

We show that to each inner function, there corresponds at least one interpolating Blaschke product whose angular derivatives have precisely the same behavior as the given inner function. We characterize the Blaschke products invertible in the closed algebra H-infinity[(b) over bar : b has finite angular derivative everywhere. We study the most well-known example of a Blaschke product with infinite angular derivative everywhere and show that it is an interpolating Blaschke product. We conclude the paper with a method for constructing thin Blaschke products with infinite angular derivative everywhere.

Interpolating Blaschke Products and Angular Derivatives

We show that to each inner function, there corresponds at least one interpolating Blaschke product whose angular derivatives have precisely the same behavior as the given inner function. We characterize the Blaschke products invertible in the closed algebra generated by the algebra of bounded analytic functions and the conjugates of Blaschke products with angular derivative finite everywhere. We study the most well-known example of a Blaschke product with infinite angular derivative everywhere and show that it is an interpolating Blaschke product. We conclude the paper with a method for constructing thin Blaschke products with infinite angular derivative everywhere.

The Effect of Sequence of Operations on Fatigue Life of LSP Treated Open-hole Aluminium Specimens

Fastener holes in aeronautical structures are typical sources of fatigue cracks due to their induced local stress concentration. A very efficient solution to this problem is to establish compressive residual stresses around the fastener holes that retard the fatigue crack nucleation and its subsequent local propagation. Previous work done on the subject of the application of LSP treatment on thin, open-hole specimens [1] has proven that the LSP effect on fatigue life of treated specimens can be detrimental, if the process is not properly optimized. In fact, it was shown that the capability of the LSP to introduce compressive residual stresses around fastener holes in thin-walled structures representative of typical aircraft constructions was not superior to the performance of conventional techniques, such as cold-working.

Fatigue in laser shock peened open-hole thin aluminium specimens

An experimental study was performed in order to determine the influence of the sequence of operations on the effectiveness of Laser Shock Peening (LSP) treatment in increasing the fatigue performances of open-hole aluminium specimens. Residual stress measurements, fractographic analysis and FEM analysis were performed, indicating the presence of compressive residual stresses on the surface of the treated specimens and tensile residual stresses in the mid-section along the thickness of the specimens. Negative effects on fatigue lives were encountered on the specimens with the hole already present, while positive effect were observed in specimens in which the hole was drilled after LSP treatment. These results indicate that LSP can be a good solution for “in production” application, in which open holes are to be drilled after the LSP treatment. The application in which LSP is used “in service” on structures with pre-existing cut-outs, has proven to be impracticable in the investigated configuration.

Influence of fabrication steps on optical and electrical properties of InN thin films

This paper reports on a case study of the impact of fabrication steps on InN material properties. We discuss the influence of annealing time and sequence of device processing steps. Photoluminescence (PL), surface morphology and electrical transport (electrical resistivity and low frequency noise) properties have been studied as responses to the adopted fabrication steps. Surface morphology has a strong correlation with annealing times, while sequences of fabrication steps do not appear to be influential. In contrast, the optical and electrical properties demonstrate correlation with both etching and thermal annealing. For all the studied samples PL peaks were in the vicinity of 0.7 eV, but the intensity and full width at half maximum (FWHM) demonstrate a dependence on the technological steps followed. Sheet resistance and electrical resistivity seem to be lower in the case of high defect introduction due to both etching and thermal treatments. The same effect is revealed through 1/f noise level measurements. A reduction of electrical resistivity is connected to an increase in 1/f noise level.

Assembly of τ protein into Alzheimer paired helical filaments depends on a local sequence motif (306VQIVYK311) forming β structure

We have searched for a minimal interaction motif in τ protein that supports the aggregation into Alzheimer-like paired helical filaments. Digestion of the repeat domain with different proteases yields a GluC-induced fragment comprising 43 residues (termed PHF43), which represents the third repeat of τ plus some flanking residues. This fragment self assembles readily into thin filaments without a paired helical appearance, but these filaments are highly competent to nucleate bona fide PHFs from full-length τ. Probing the interactions of PHF43 with overlapping peptides derived from the full τ sequence yields a minimal hexapeptide interaction motif of 306VQIVYK311 at the beginning of the third internal repeat. This motif coincides with the highest predicted β-structure potential in τ. CD and Fourier transform infrared spectroscopy shows that PHF43 acquires pronounced β structure in conditions of self assembly. Point mutations in the hexapeptide region by proline-scanning mutagenesis prevent the aggregation. The data indicate that PHF assembly is initiated by a short fragment containing the minimal interaction motif forming a local β structure embedded in a largely random-coil protein.

Sequence stratigraphy and sea-level history of Kangan formation in south pars field

Dehram group includes Faraghan, Dalan and Kangan formations. Kangan formation ages lower terias. That is one of the important reservoir rocks of southern Iran and Persian Gulf. In this research Kangan formation is studied in two A and B wells. Based on 75 studies on thin section, four carbonate litho acies association A, B, C, D with 12 subfacies are identified. A lithofacies association includes 4 subfacies: A1, A2, A3 and A4. B lithofacies association consists of 3 subfacies: B1, B2 and B3. C lithofacies association consists of 3 subfacies: C1, C2, C3 and D lithofacies association includes 2 subfacies: D1 and D2. On the base of studies lithofacies association of Kangan formations are formed in 3 environments of: Tidal Flat, Lagoon and Barrier Shore Complex in a Carbonated Platform Ramp type. Diagenetic processes have effected this formation. The most important Diagenetic processes are: Cementation, Anhydritization, Micrization, Neomorphism, Bioturbation, Dissolution, Compaction, Dolomitization and Porosity. Sequence staratigraphy studies were performed base on the vertical and horizontal relationship of lithofacies association and well logging in gamma ray and sonic type that causes the identification of two sedimentary sequences: First sedimentary sequence includes: Transgressive System Tract (TST) and High Stand System Tract (HST). The lower boundary of this sequence is in Sequence Boundary 1 (SB1) which shows unconformities of Dalan and Kangan that are Permian-terias unconformities. The upper boundary is in Sequence Boundary 2 (SB2) type that is identified by carbonate facies associated by anhydrite nodular. Second sedimentary sequence includes: TST and HST. Lower and upper boundaries of these sequences are both in SB2 type. The lower and upper boundary is made of carbonate facies with anhydrite nodular.

Chatter avoidance in the milling of thin floors with bull-nose end mills: Model and stability diagrams

The milling of thin parts is a high added value operation where the machinist has to face the chatter problem. The study of the stability of these operations is a complex task due to the changing modal parameters as the part loses mass during the machining and the complex shape of the tools that are used. The present work proposes a methodology for chatter avoidance in the milling of flexible thin floors with a bull-nose end mill. First, a stability model for the milling of compliant systems in the tool axis direction with bull-nose end mills is presented. The contribution is the averaging method used to be able to use a linear model to predict the stability of the operation. Then, the procedure for the calculation of stability diagrams for the milling of thin floors is presented. The method is based on the estimation of the modal parameters of the part and the corresponding stability lobes during the machining. As in thin floor milling the depth of cut is already defined by the floor thickness previous to milling, the use of stability diagrams that relate the tool position along the tool-path with the spindle speed is proposed. Hence, the sequence of spindle speeds that the tool must have during the milling can be selected. Finally, this methodology has been validated by means of experimental tests.