Development of an equipment for thermal characterization of shape memory alloy actuators using thermoelectric effect

Nesta dissertação apresenta-se o desenvolvimento de um equipamento de análise térmica cuja técnica termoanalitica utilizada é a termoeletrometria. O equipamento desenvolvido é direcionado a caracterização das temperaturas de transformação de fase e histerese térmica de Ligas com Memória de Forma (LMF). Para tanto, foi projetada e fabricada uma plataforma de teste capaz de submeter uma amostra de LMF a um programa controlado de temperatura, armazenando e apresentando em tempo real as medidas da resistência elétrica e/ou os sinais de tensão elétrica na amostra. Essa plataforma utiliza uma pastilha termoelétrica que funciona segundo o efeito Peltier para produzir o resfriamento e aquecimento da amostra de LMF. O equipamento permite realizar ciclos térmicos sucessivos entre temperaturas mínimas e máximas situadas entre – 50 oC e 150 oC, com controle de taxa de resfriamento e aquecimento através de um controlador fuzzy. Para validar o sistema desenvolvido foram feitos testes em amostras de LMF da família Ni-Ti, além da determinação da resistividade elétrica do cobre elétrico comercialmente puro. Os resultados obtidos permitiram o levantamento das curvas de caracterização Temperatura (ºC) versus Resistência (Ω), as quais apresentaram comportamentos conforme previsto pela literatura. De um ponto de vista prático, o trabalho desenvolvido originou um equipamento de caracterização experimental para o estudo fundamental de atuadores de LMF, o qual será constantemente utilizado nas pesquisas desenvolvidas pelo Laboratório Multidisciplinar de Materiais e Estruturas Ativas (LaMMEA) da UAEM/CCT/UFCG.This work presents a development of equipment for thermal analysis which used thermoelectrometry technique. The equipment is directed to the characterization of transformation temperatures and thermal hysteresis of shape memory alloys (SMA). Therefore, it was designed and assembled an test platform for submitting a SMA sample to a controlled temperature program, also hold real-time measurements of electrical resistance or voltage signals in the SMA sample. This platform has as main component a thermoelectric tablet that works by Peltier effect to produce cooling and heating of the SMA sample. The device allow make successive thermal cycles between minimum and maximum temperatures in the temperature range from - 50 ºC to 150 ºC, with controlled rate cooling and heating through the implementation of a fuzzy controller. To validate the developed system some tests were performed using Ni-Ti SMA samples. In addition, the electrical resistivity of commercial copper was also determined with the apparatus. The obtained results of Resistance (Ω) vs. Temperature (ºC) characterization curves are in accord with literature. From a practical standpoint, the work led to experimental characterization equipment for the fundamental study of shape memory alloys, which will be constantly used in the research developed by the Multidisciplinary Laboratory of Active Materials and Structures (LaMMEA) of UAEM / CCT / UFCG.CNP

NEOTROPICAL ALIEN MAMMALS: a data set of occurrence and abundance of alien mammals in the Neotropics

Biological invasion is one of the main threats to native biodiversity. For a species to become invasive, it must be voluntarily or involuntarily introduced by humans into a nonnative habitat. Mammals were among first taxa to be introduced worldwide for game, meat, and labor, yet the number of species introduced in the Neotropics remains unknown. In this data set, we make available occurrence and abundance data on mammal species that (1) transposed a geographical barrier and (2) were voluntarily or involuntarily introduced by humans into the Neotropics. Our data set is composed of 73,738 historical and current georeferenced records on alien mammal species of which around 96% correspond to occurrence data on 77 species belonging to eight orders and 26 families. Data cover 26 continental countries in the Neotropics, ranging from Mexico and its frontier regions (southern Florida and coastal-central Florida in the southeast United States) to Argentina, Paraguay, Chile, and Uruguay, and the 13 countries of Caribbean islands. Our data set also includes neotropical species (e.g., Callithrix sp., Myocastor coypus, Nasua nasua) considered alien in particular areas of Neotropics. The most numerous species in terms of records are from Bos sp. (n = 37,782), Sus scrofa (n = 6,730), and Canis familiaris (n = 10,084); 17 species were represented by only one record (e.g., Syncerus caffer, Cervus timorensis, Cervus unicolor, Canis latrans). Primates have the highest number of species in the data set (n = 20 species), partly because of uncertainties regarding taxonomic identification of the genera Callithrix, which includes the species Callithrix aurita, Callithrix flaviceps, Callithrix geoffroyi, Callithrix jacchus, Callithrix kuhlii, Callithrix penicillata, and their hybrids. This unique data set will be a valuable source of information on invasion risk assessments, biodiversity redistribution and conservation-related research. There are no copyright restrictions. Please cite this data paper when using the data in publications. We also request that researchers and teachers inform us on how they are using the data

NEOTROPICAL CARNIVORES: a data set on carnivore distribution in the Neotropics

Mammalian carnivores are considered a key group in maintaining ecological health and can indicate potential ecological integrity in landscapes where they occur. Carnivores also hold high conservation value and their habitat requirements can guide management and conservation plans. The order Carnivora has 84 species from 8 families in the Neotropical region: Canidae; Felidae; Mephitidae; Mustelidae; Otariidae; Phocidae; Procyonidae; and Ursidae. Herein, we include published and unpublished data on native terrestrial Neotropical carnivores (Canidae; Felidae; Mephitidae; Mustelidae; Procyonidae; and Ursidae). NEOTROPICAL CARNIVORES is a publicly available data set that includes 99,605 data entries from 35,511 unique georeferenced coordinates. Detection/non-detection and quantitative data were obtained from 1818 to 2018 by researchers, governmental agencies, non-governmental organizations, and private consultants. Data were collected using several methods including camera trapping, museum collections, roadkill, line transect, and opportunistic records. Literature (peer-reviewed and grey literature) from Portuguese, Spanish and English were incorporated in this compilation. Most of the data set consists of detection data entries (n = 79,343; 79.7%) but also includes non-detection data (n = 20,262; 20.3%). Of those, 43.3% also include count data (n = 43,151). The information available in NEOTROPICAL CARNIVORES will contribute to macroecological, ecological, and conservation questions in multiple spatio-temporal perspectives. As carnivores play key roles in trophic interactions, a better understanding of their distribution and habitat requirements are essential to establish conservation management plans and safeguard the future ecological health of Neotropical ecosystems. Our data paper, combined with other large-scale data sets, has great potential to clarify species distribution and related ecological processes within the Neotropics. There are no copyright restrictions and no restriction for using data from this data paper, as long as the data paper is cited as the source of the information used. We also request that users inform us of how they intend to use the data