Vectorial bending characteristics of long-period grating written in D-shaped fibre

The curvature- or bend-sensing response of long-period gratings (LPG) UV-inscribed in D-shaped fiber has been investigated experimentally. Strong fiber orientation dependence of the spectral response when such LPGs are subjected to dynamic bending has been observed and is shown to form the basis for new vector sensors.

Crack initiation in asphalt mixtures under external compressive loads

Crack initiation was studied for asphalt mixtures under external compressive loads. High tensile localized stresses e direction of the external loads. A quantitative crack initiation criterion the edges of compressed air voids lead to the growth of wing cracks in thon was derived using pseudostrain energy balance principle. Bond energy is determined and it increases with aging and loading rate while decreases with temperature. Cohesive and adhesive cracking occur simultaneously and a method was proposed to determine the individual percentage. The crack initiation criterion is simplified and validated through comparing the predicted and measured compressive strength of the asphalt mixtures.

Anisotropic characterization of crack growth in the tertiary flow of asphalt mixtures in compression

Asphalt mixtures exhibit primary, secondary, and tertiary stages in sequence during a rutting deterioration. Many field asphalt pavements are still in service even when the asphalt layer is in the tertiary stage, and rehabilitation is not performed until a significant amount of rutting accompanied by numerous macrocracks is observed. The objective of this study was to provide a mechanistic method to model the anisotropic cracking of the asphalt mixtures in compression during the tertiary stage of rutting. Laboratory tests including nondestructive and destructive tests were performed to obtain the viscoelastic and viscofracture properties of the asphalt mixtures. Each of the measured axial and radial total strains in the destructive tests were decomposed into elastic, plastic, viscoelastic, viscoplastic, and viscofracture strains using the pseudostrain method in an extended elastic-viscoelastic correspondence principle. The viscofracture strains are caused by the crack growth, which is primarily signaled by the increase of phase angle in the tertiary flow. The viscofracture properties are characterized using the anisotropic damage densities (i.e., the ratio of the lost area caused by cracks to the original total area in orthogonal directions). Using the decomposed axial and radial viscofracture strains, the axial and radial damage densities were determined by using a dissipated pseudostrain energy balance principle and a geometric analysis of the cracks, respectively. Anisotropic pseudo J-integral Paris' laws in terms of damage densities were used to characterize the evolution of the cracks in compression. The material constants in the Paris' law are determined and found to be highly correlated. These tests, analysis, and modeling were performed on different asphalt mixtures with two binders, two air void contents, and three aging periods. Consistent results were obtained; for instance, a stiffer asphalt mixture is demonstrated to have a higher modulus, a lower phase angle, a greater flow number, and a larger n1 value (exponent of Paris' law). The calculation of the orientation of cracks demonstrates that the asphalt mixture with 4% air voids has a brittle fracture and a splitting crack mode, whereas the asphalt mixture with 7% air voids tends to have a ductile fracture and a diagonal sliding crack mode. Cracks of the asphalt mixtures in compression are inclined to propagate along the direction of the external compressive load. © 2014 American Society of Civil Engineers.

Long period grating in multicore optical fiber:an ultra-sensitive vector bending sensor for low curvatures

Long period grating was UV inscribed into a multicore fiber consisting of 120 single mode cores. The multicore fiber that hosts the grating was fusion spliced into a single mode fiber at both ends. The splice creates a taper transition between the two types of fiber that produces a nonadiabatic mode evolution; this results in the illumination of all the modes in the multicore fiber. The spectral characteristics of this fiber device as a function of curvature were investigated. The device yielded a significant spectral sensitivity as high as 1.23 nm/m-1 and 3.57 dB/m-1 to the ultra-low curvature values from 0 to 1 m-1. This fiber device can also distinguish the orientation of curvature experienced by the fiber as the long period grating attenuation bands producing either a blue or red wavelength shift. The finite element method (FEM) model was used to investigate the modal behavior in multicore fiber and to predict the phase-matching curves of the long period grating inscribed into multicore fiber. © 2014 Optical Society of America.

On a Hypersingular Equation of a Problem, for a Crack in Elastic Media

Mathematics Subject Classification 2010: 45DB05, 45E05, 78A45.

On a 3D-Hypersingular Equation of a Problem for a Crack

MSC 2010: 45DB05, 45E05, 78A45

Crack Theory with Singularities at the Boundary

2002 Mathematics Subject Classification: 35S15, 35J70, 35J40, 38J40

Dual core photonic crystal fiber based Mach-Zehnder interferometer assisted with two tapers for bending measurement

A bending sensor is achieved by employing a singlemode fiber-dual core photonic crystal fiber- singlemode fiber (SDS) structure with two tapers at fusing points. A sensitivity of - 4.3421nm/m∼ between the transmission spectra shift and curvature is demonstrated. © 2013 IEEE.

Optimal redistricting under geographical constraints: Why "pack and crack" does not work

We show that optimal partisan redistricting with geographical constraints is a computationally intractable (NP-complete) problem. In particular, even when voter's preferences are deterministic, a solution is generally not obtained by concentrating opponent's supporters in \unwinnable" districts ("packing") and spreading one's own supporters evenly among the other districts in order to produce many slight marginal wins ("cracking").

Crack tip stress study for elastic-perfectly plastic materials with some applications

The problems of plasticity and non-linear fracture mechanics have been generally recognized as the most difficult problems of solid mechanics. The present dissertation is devoted to some problems on the intersection of both plasticity and non-linear fracture mechanics. The crack tip is responsible for the crack growth and therefore is the focus of fracture science. The problem of crack has been studied by an army of outstanding scholars and engineers in this century, but has not, as yet, been solved for many important practical situations. The aim of this investigation is to provide an analytical solution to the problem of plasticity at the crack tip for elastic-perfectly plastic materials and to apply the solution to a classical problem of the mechanics of composite materials.^ In this work, the stresses inside the plastic region near the crack tip in a composite material made of two different elastic-perfectly plastic materials are studied. The problems of an interface crack, a crack impinging an interface at the right angle and at arbitrary angles are examined. The constituent materials are assumed to obey the Huber-Mises yielding condition criterion. The theory of slip lines for plane strain is utilized. For the particular homogeneous case these problems have two solutions: the continuous solution found earlier by Prandtl and modified by Hill and Sokolovsky, and the discontinuous solution found later by Cherepanov. The same type of solutions were discovered in the inhomogeneous problems of the present study. Some reasons to prefer the discontinuous solution are provided. The method is also applied to the analysis of a contact problem and a push-in/pull-out problem to determine the critical load for plasticity in these classical problems of the mechanics of composite materials.^ The results of this dissertation published in three journal articles (two of which are under revision) will also be presented in the Invited Lecture at the 7$\rm\sp{th}$ International Conference on Plasticity (Cancun, Mexico, January 1999). ^

A phenomenology of crack abuse

The aim of this dissertation is to identify, describe, and explain the common experiences defining the crack abuser's life-world. Its method is phenomenological. Using basic cybernetic premises, a neurophysiologically oriented phenomenological framework concerning the constitution of thoughts, memories, and perceptions is first written. The framework is designed to hypothetically represent the neuropathology of crack abuse within a perspective that prescinds and describes the constitution, flow, and interdependence of experience. After the framework is written, the dissertation outlines the neuro-psychopharmacology of crack abuse and delimits crack abusers as a specific group within the more general population of cocaine users. It then represents the neuropathology of crack abuse within its phenomenological framework and uses the first-person accounts of forty-two crack dependents to actualize a phenomenological sketch of the crack abuser's life-world. The ethnographies afford the possibility of writing a “thick” description of the crack abuser's daily life—one that communicates the substance, order, and subjective and cultural dimensions of the dependent's defining experiences. ^ The dissertation's goals are successfully realized. The framework written and the ethnographies recorded and transcribed, the dissertation is able to identify, describe, and to a certain extent explain some of the common experiences defining the crack abusers life-world. The dissertation concludes that the crack abuser's life-world is organized around three primary and four secondary experiences. His primary experiences include: (1) an almost complete, yet fleeting, satisfaction of the ego's innate insufficiency and sublime, erotic-like stimulation of its core, (2) a fundamental inclination and expansion of the uniquely oriented euphoria-dysphoria dynamic that vivifies and orients the flow of consciousness, and (3) a change in the ego's innate structure. His secondary experiences include: (a) a characteristic aiming of projects, actions, and conduct toward the procurement and consumption of crack, (b) a denigration in the hold of legitimations and institutionalizations on the thematic field, (c) a strict alignment and a contraction in the scope of logical types pointing to the salient experiences within the stock of knowledge, and (d) for some crack abusers, ontological insecurity, despair, and exhaustion. ^

Usuários de crack, instituições e modos de subjetivação: estudo das práticas e da eficácia terapêutica em uma comunidade terapêutica religiosa (RN)

This anthropological research has as main goal to grasp the meanings and perceptions - mode of subjectivity - of crack users in relation to the proposals of Therapeutic Communities (TC) of religious character. The work emphasizes the analysis of Therapeutic Communities of Rio Grande do Norte state, studying a particular organization, called Anzóis da Dor. I intend to analyze qualitative data, focusing on an analysis of the discursive content of speeches and the observation of social interaction, which results in an ethnographic text characterized by a dense description. In relation to the dissertation’s specific goals, we seek to present a general overview of the emergence and development of Therapeutic Communities – encompassing general and local considerations - and pointing out to the dynamics of religious healing systems of these institutions, besides the principles that guide them. In methodological terms, I conducted the partial mapping of therapeutic communities located in Rio Grande do Norte state; interviews with Therapeutic Communities coordinators, visits, participant observation in one of these institutions as well as some interviews with crack users and people close to these social agents in relation to the Therapeutic Communities and the treatment offered by them

Efeito do topiramato sobre o craving em usuários de crack

The study aims to analyze the effects of topiramato on the craving of crack users. It is an open crossover clinical trial involving users from the Psychosocial Care Center for Alcohol and Drugs (CAPSad) in city of Parnamirim, RN, approved by the CEP CAAE: 38710614.1.0000.5537, respecting the norms of the resolution n. 466/2012/CNS. The study produced preliminary two scientific papers: a theoretical essay and an integrative review, as a way of seeking the state of art. The first paper was based in the theoretical framework of Hinds, Chaves and Cypress, which focuses different contexts, from the issues of individual use to the coping policies in Brazil, highlighting that the situation and the complexity of the phenome requires coping strategies for the full attention to the user, family and society. As a result of the integrative review, among the 902 retrieved records, eight of them presented therapeutic schemes with positive effects for the craving of cocaine. They used nine different drugs. It is important to spot out that there was no result for the craving of crack. The data collection was conducted from December 2014 to July 2015 and has as sample predominantly single males. The sample was composed of 30 subjects who met the inclusion criteria: adults, age from 18 years, diagnosis of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) for cocaine/crack; cognitive capacity preserved; attendance to the service, participated at least three visits in the 12 months prior to data collection; and accepted to be monitored in the proposed treatment. Data was analyzed using descriptive statistics from the Statistical Package of Support for Social Sciences (SPSS) on the instruments: 1) Alcohol, Smoking, and Substance Involvement Screening Test (ASSIST), pointing out, among other results, that only 14% used crack/cocaine weekly during treatment, while 83% used daily or weekly after the washout period; 2) Barratt Impulsiveness Scale, with an average of 80.23 and 77.47 with and without drug treatment, respectively. An analysis from the Student t test show no significant differences in impulsivity with or without the drug; and 3) Cocaine-Craving Questionnaire-Brief (CCK-B), indicating that the number of users with craving intensity level is significantly higher without drug treatment (86%) than with treatment (33%). The analysis between craving and level of impulsivity showed that there is a low correlation (Pearson) between these two variables during treatment and after the washout, demonstrating that impulsivity has low influence on the outcome of drug therapy. As conclusion, it was noted that the topiramate produces positive effect on reducing the craving for crack users and their use is a relevant strategy for efficacy in the treatment of crack users.

Efeito do topiramato sobre o craving em usuários de crack

The study aims to analyze the effects of topiramato on the craving of crack users. It is an open crossover clinical trial involving users from the Psychosocial Care Center for Alcohol and Drugs (CAPSad) in city of Parnamirim, RN, approved by the CEP CAAE: 38710614.1.0000.5537, respecting the norms of the resolution n. 466/2012/CNS. The study produced preliminary two scientific papers: a theoretical essay and an integrative review, as a way of seeking the state of art. The first paper was based in the theoretical framework of Hinds, Chaves and Cypress, which focuses different contexts, from the issues of individual use to the coping policies in Brazil, highlighting that the situation and the complexity of the phenome requires coping strategies for the full attention to the user, family and society. As a result of the integrative review, among the 902 retrieved records, eight of them presented therapeutic schemes with positive effects for the craving of cocaine. They used nine different drugs. It is important to spot out that there was no result for the craving of crack. The data collection was conducted from December 2014 to July 2015 and has as sample predominantly single males. The sample was composed of 30 subjects who met the inclusion criteria: adults, age from 18 years, diagnosis of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) for cocaine/crack; cognitive capacity preserved; attendance to the service, participated at least three visits in the 12 months prior to data collection; and accepted to be monitored in the proposed treatment. Data was analyzed using descriptive statistics from the Statistical Package of Support for Social Sciences (SPSS) on the instruments: 1) Alcohol, Smoking, and Substance Involvement Screening Test (ASSIST), pointing out, among other results, that only 14% used crack/cocaine weekly during treatment, while 83% used daily or weekly after the washout period; 2) Barratt Impulsiveness Scale, with an average of 80.23 and 77.47 with and without drug treatment, respectively. An analysis from the Student t test show no significant differences in impulsivity with or without the drug; and 3) Cocaine-Craving Questionnaire-Brief (CCK-B), indicating that the number of users with craving intensity level is significantly higher without drug treatment (86%) than with treatment (33%). The analysis between craving and level of impulsivity showed that there is a low correlation (Pearson) between these two variables during treatment and after the washout, demonstrating that impulsivity has low influence on the outcome of drug therapy. As conclusion, it was noted that the topiramate produces positive effect on reducing the craving for crack users and their use is a relevant strategy for efficacy in the treatment of crack users.

An irregular lattice model to simulate crack paths in bonded granular assemblies

Peer reviewed