Modeling and Experimental Aspects of Self-healing Bolted Joint through Shape Memory Alloy Actuators

Bolted joints are a form of mechanical coupling largely used in machinery due to their reliability and low cost. Failure of bolted joints can lead to catastrophic events, such as leaking, train derailments, aircraft crashes, etc. Most of these failures occur due to the reduction of the pre-load, induced by mechanical vibration or human errors in the assembly or maintenance process. This article investigates the application of shape memory alloy (SMA) washers as an actuator to increase the pre-load on loosened bolted joints. The application of SMA washer follows a structural health monitoring procedure to identify a damage (reduction in pre-load) occurrence. In this article, a thermo-mechanical model is presented to predict the final pre-load achieved using this kind of actuator, based on the heat input and SMA washer dimension. This model extends and improves on the previous model of Ghorashi and Inman [2004, "Shape Memory Alloy in Tension and Compression and its Application as Clamping Force Actuator in a Bolted Joint: Part 2 - Modeling," J. Intell. Mater. Syst. Struct., 15:589-600], by eliminating the pre-load term related to nut turning making the system more practical. This complete model is a powerful but complex tool to be used by designers. A novel modeling approach for self-healing bolted joints based on curve fitting of experimental data is presented. The article concludes with an experimental application that leads to a change in joint assembly to increase the system reliability, by removing the ceramic washer component. Further research topics are also suggested.

Traumatic subdural hygromas: Proposed pathogenesis based classification

Background: Traumatic subdural hygroma (TSHy) is an accumulation of cerebrospinal fluid (CSF) in the subdural space after head injury. It appears to be relatively common, but its onset time and natural history are not well defined. Considered a benign epiphenomenon of trauma, the pathogenesis of TSHy is still unclear and many questions remain unanswered. This study adds to the information on TSHy, and proposes a classification based on pathogenesis.Methods: Thirty-four consecutive adult patients with TSHy were analyzed for clinical evolution and serial CT scan, during a period of several months. TSHy diagnosis was based on published CT scan criteria of hypodense subdural collection after trauma, without enhancement and neomembrane, with a minimum distance of 3 mm between the skull and brain. Ventricle size was analyzed by calculating the bicaudate index (BCI). For comparison, the BCI was measured from CT scan at three moments: admission, at time of TSHy diagnosis, and from last CT scan.Results: There were 34 patients, aged between 16 and 85 years (mean 40), half of them were below 40 years. Road traffic crashes were the main cause of head injury. The mean time for hygroma diagnosis was 9 days. Twenty-one patients (61.8%) underwent conservative treatment for TSHy and 13 (38.2%), surgical treatment. TSHy are early lesions and can be detected in the first 24 hours after trauma, usually as small subdural effusion (SSEff). Based on clinical and CT scan findings, we divided the 34 patients into 3 groups, (Ia and Ib) without evident mass effect and (II) with evident mass effect. Group Ia includes patients without ventricle dilation; Ib, patients with associated ventricle dilations.Conclusions: SSEff detected in the first 24 hours posttrauma in our series evolved into TSHy suggesting that this is an early lesion; all THSy were divided in three groups according to the pathophysiologic mechanism. These three groups probably represent a continuum of CSF absorption impairment. Group la represents what most authors consider a simple hygroma, with no impairment on CSF absorption. Group Ib represent the external hydrocephalus form with various degrees of CSF imbalance, and group II were the cases presenting marked mass effect.

Occurrence of tooth injuries in patients treated in hospital environment in the region of Aracatuba, Brazil during a 6-year period

Dental trauma has been considered as a public health problem that affects mainly children and youngsters and due to its impact on the patient's quality of life. This study presents the results of a 6-year survey of the occurrence and characteristics of dental trauma in patients admitted to the Service of Surgery and Oral and Maxillofacial Traumatology of the School of Dentistry of Aracatuba (UNESP, Brazil) after emergency care in hospital facilities in the region of Aracatuba, SP, Brazil. For such purpose, the clinical files of patients treated at the Service between 1999 and 2005 were reviewed. Information regarding gender, age, number of traumatized teeth, etiology and diagnosis of the trauma was collected from the files of patients with tooth injuries and recorded in case report forms specifically designed for this purpose. The results showed that from a total of 4112 patients admitted to the Service within the surveyed period, 266 (6.5%) had tooth injuries (172 males - 64.7%; 94 females - 35.3%). The total number of traumatized teeth was 496. Most patients belonged to the 16-20 year-old age group (20.3%) and the most frequent causes of tooth injuries were bicycle accidents (28.6%), motorcycle accidents (19.2%) and falls (18.8%). Injuries to the periodontal tissues were the most frequent type of tooth injuries (408 teeth; 82.26%), occurring in 118 primary and 290 permanent teeth. Among the injuries to the periodontal tissues, avulsion was the most common (32.86%) (29.41% for primary and 34.0% for permanent teeth), followed by extrusive luxation (19.15%) (25.21% for primary and 17.24% for permanent teeth). In conclusion, in the surveyed population, cases of tooth injuries were more frequent in males aged 16-20 years old due to cyclist accidents with predominance of injuries to the periodontal tissues, in particular, avulsions.

Reconstrução do L.C.P. do joelho: técnica de fixação no leito tibial (INLAY). Avaliação objetiva e subjetiva de 30 casos

A reconstrução cirúrgica do ligamento cruzado posterior (L.C.P.) do joelho ainda permanece como um grande desafio terapêutico. Neste trabalho avaliamos 30 pacientes submetidos à reconstrução cirúrgica do L.C.P. com a técnica de fixação do enxerto tendíneo no leito tibial por abordagem direta (INLAY). 28 pacientes eram do sexo masculino e 2 do feminino, com idade média de 31,10 anos. O tempo médio de lesão foi de 34,24 meses em 67% dos casos a lesão foi secundária a acidente motociclístico. As lesões condrais e do ligamento cruzado anterior (L.C.A.) do joelho estavam presentes em 67% e 33% dos casos, respectivamente. Os pacientes foram avaliados objetivamente (teste de gaveta posterior) e subjetivamente (Escala de Lysholm). O seguimento pós-operatório médio foi de 21,7 meses. Cerca de 66% dos casos foram classificados como bom e excelente na avaliação subjetiva e objetiva. A análise estatística apresentou comportamento semelhante para as duas avaliações.Os resultados clínicos pós-operatórios obtidos neste trabalho têm nos encorajado a seguir com esta técnica cirúrgica.

Tratamento cirúrgico da fratura-avulsão da inserção tibial do L.C.P. do joelho: experiência de 21 casos

Avaliamos 21 pacientes, sendo 16 pacientes do sexo masculino e 5 do feminino, com idade média de 30 anos, foram submetidos à tratamento cirúrgico da fratura-avulsão do LCP. em 57% dos casos a lesão foi secundária a acidente motociclístico e 19% a acidente automobilístico. em 72% dos casos foi identificada uma lesão na face anterior do joelho. O tratamento cirúrgico consistiu na abordagem posterior do joelho e fixação do fragmento ósseo com parafuso e arruela em 18 casos; e amarrilhas trans-ósseas em 3 casos, onde o fragmento ósseo era muito pequeno. em 91% dos casos, a cirurgia foi realizada dentro dos primeiros 15 dias apos a lesão. Os pacientes foram avaliados objetivamente (teste de gaveta posterior) e subjetivamente (Escala de Lysholm), apos um seguimento pós-operatório mínimo de 12 meses. A análise estatística não mostrou diferença significativa, ao nível de 5%, entre as avaliações objetiva e subjetiva. A ausência de lesão ligamentar periférica pode ter contribuído para que os resultados clínicos pós-operatórios tenham avaliação subjetiva satisfatória; entretanto, a presença de uma posteriorização tibial residual sugere que a fratura-avulsão do ligamento cruzado posterior deve ser abordada não como uma lesão óssea pura, mas sim, como uma lesão ósteo-ligamentar.

Epidemiologic Evaluation of Mandibular Fractures in the Rio de Janeiro High-Complexity Hospital

The aim of this study was to gather data on trauma etiology and mandibular fracture localization in patients who presented at the General Hospital of Nova Iguacu, Rio de Janeiro, Brazil. From March 2007 to December 2008, 95 patients with mandibular fracture were registered in a medical form, at the Bucomax-illofacial Surgery Department of the General Hospital of Nova Iguacu, Rio de Janeiro, Brazil. Concerning mandibular fracture etiology, 21.05% were caused by motorcycle accidents, followed by interpersonal violence without use of weapons (punches, kicks, bumps with the head, blows with the elbow, etc) (16.84%) and interpersonal violence with firearm (14.73%). It was found that 52.63% of the patients had a single fracture line. The most affected fracture area was the parasymphysis (26.02%), followed by the condyle (22.60%) and mandibular angle (18.49%). Concerning the injury area, 24.21% were directed to the mandibular symphysis, 22.17% of the patients did not remember the injury area, and 18.94% had multiple injuries. When the injury was directed to the symphysis, the result was more condyle fractures (11.64%), and injuries at the mandibular angle resulted in fractures at the angle itself (8.90%). The most common fracture cause was traffic accidents, mainly motorcycle accidents, and the most affected areas were the parasymphysis and the condyle. The mandible isolated fractures occurred in half of the cases. Motorcycle accidents resulted in more fractures in the parasymphysis area, and when the symphysis area is affected by injuries, the result is a higher percentage in condyle fractures.

Semiautomatic dental recognition using a graph-based segmentation algorithm and teeth shapes features

Dental recognition is very important for forensic human identification, mainly regarding the mass disasters, which have frequently happened due to tsunamis, airplanes crashes, etc. Algorithms for automatic, precise, and robust teeth segmentation from radiograph images are crucial for dental recognition. In this work we propose the use of a graph-based algorithm to extract the teeth contours from panoramic dental radiographs that are used as dental features. In order to assess our proposal, we have carried out experiments using a database of 1126 tooth images, obtained from 40 panoramic dental radiograph images from 20 individuals. The results of the graph-based algorithm was qualitatively assessed by a human expert who reported excellent scores. For dental recognition we propose the use of the teeth shapes as biometric features, by the means of BAS (Bean Angle Statistics) and Shape Context descriptors. The BAS descriptors showed, on the same database, a better performance (EER 14%) than the Shape Context (EER 20%). © 2012 IEEE.

Identifying financial crises in real time

Following the thermodynamic formulation of a multifractal measure that was shown to enable the detection of large fluctuations at an early stage, here we propose a new index which permits us to distinguish events like financial crises in real time. We calculate the partition function from which we can obtain thermodynamic quantities analogous to the free energy and specific heat. The index is defined as the normalized energy variation and it can be used to study the behavior of stochastic time series, such as financial market daily data. Famous financial market crashes-Black Thursday (1929), Black Monday (1987) and the subprime crisis (2008)-are identified with clear and robust results. The method is also applied to the market fluctuations of 2011. From these results it appears as if the apparent crisis of 2011 is of a different nature to the other three. We also show that the analysis has forecasting capabilities. © 2012 Elsevier B.V. All rights reserved.

Avaliação da movimentação de cães por meio de captura-recaptura fotográfica e georeferenciamento

Pós-graduação em Ciência Animal - FMVA

Projeto, desenvolvimento e avaliação de um penetrômetro elétrico-eletrônico para uso em tanques de solo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Asas do trabalho: um estudo do sofrimento dos mototaxistas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo de acidentes com motocicletas no município de Presidente Prudente no ano de 2003

Pós-graduação em Saúde Coletiva - FMB

Acidentes de trabalho atendidos pelo serviço integrado de atendimento ao trauma em emergências, Londrina-PR

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Motociclistas vítimas de acidentes em Paranavaí, 2011

Pós-graduação em Saúde Coletiva - FMB

Intraoperative Cardiac Arrest and Mortality in Trauma Patients. A 14-Yr Survey from a Brazilian Tertiary Teaching Hospital

Background: Little information on the factors influencing intraoperative cardiac arrest and its outcomes in trauma patients is available. This survey evaluated the associated factors and outcomes of intraoperative cardiac arrest in trauma patients in a Brazilian teaching hospital between 1996 and 2009.Methods: Cardiac arrest during anesthesia in trauma patients was identified from an anesthesia database. The data collected included patient demographics, ASA physical status classification, anesthesia provider information, type of surgery, surgical areas and outcome. All intraoperative cardiac arrests and deaths in trauma patients were reviewed and grouped by associated factors and also analyzed as totally anesthesia-related, partially anesthesia-related, totally surgery-related or totally trauma patient condition-related.Findings: Fifty-one cardiac arrests and 42 deaths occurred during anesthesia in trauma patients. They were associated with male patients (P<0.001) and young adults (18-35 years) (P = 0.04) with ASA physical status IV or V (P<0.001) undergoing gastroenterological or multiclinical surgeries (P<0.001). Motor vehicle crashes and violence were the main causes of trauma (P<0.001). Uncontrolled hemorrhage or head injury were the most significant associated factors of intraoperative cardiac arrest and mortality (P<0.001). All cardiac arrests and deaths reported were totally related to trauma patient condition.Conclusions: Intraoperative cardiac arrest and mortality incidence was highest in male trauma patients at a younger age with poor clinical condition, mainly related to uncontrolled hemorrhage and head injury, resulted from motor vehicle accidents and violence.