Monitoring Single-point Dressers Using Fuzzy Models

AbstractGrinding causes progressive dulling and glazing of the grinding wheel grains and clogging of the voids on the wheel's surface with ground metal dust particles, which gradually increases the grinding forces. The condition of the grains at the periphery of a grinding wheel strongly influences the damage induced in a ground workpiece. Therefore, truing and dressing must be carried out frequently. Dressing is the process of conditioning the grinding wheel surface to reshape the wheel when it has lost its original shape through wear, giving the tool its original condition of efficiency. Despite the very broad range of dressing tools available today, the single-point diamond dresser is still the most widely used dressing tool due to its great versatility. The aim of this work is to predict the wear level of the single-point dresser based on acoustic emission and vibration signals used as input variables for fuzzy models. Experimental tests were performed with synthetic diamond dressers on a surface-grinding machine equipped with an aluminum oxide grinding wheel. Acoustic emission and vibration sensors were attached to the tool holder and the signals were captured at 2MHz. During the tests, the wear of the diamond tip was measured every 20 passes using a microscope with 10 to 100 X magnification. A study was conducted of the frequency content of the signals, choosing the frequency bands that best correlate with the diamond's wear. Digital band-pass filters were applied to the raw signals, after which two statistics were calculated to serve as the inputs for the fuzzy models. The results indicate that the fuzzy models using the aforementioned signal statistics are highly effective for predicting the wear level of the dresser

Astrophysics from data analysis of spherical gravitational wave detectors

The direct detection of gravitational waves will provide valuable astrophysical information about many celestial objects. Also, it will be an important test to general relativity and other theories of gravitation. The gravitational wave detector SCHENBERG has recently undergone its first test run. It is expected to have its first scientific run soon. In this work the data analysis system of this spherical, resonant mass detector is tested through the simulation of the detection of gravitational waves generated during the inspiralling phase of a binary system. It is shown from the simulated data that it is not necessary to have all six transducers operational in order to determine the source's direction and the wave's amplitudes.Comment: 8 pages and 3 figure

Tocopherol and fatty acids content and proximal composition of four avocado cultivars (Persea Americana Mill)

Avocado pulp is widely regarded as a great source of edible oil containing fat-soluble vitamins and omega-3 fatty acids (FA). However, avocado peel and seeds are also good sources of edible oil and are less explored byproducts. This paper aimed at determining the proximal composition, FA and tocopherol contents of the pulp, peel, and seeds of Quintal, Fortuna, Margarida, and Hass avocado cultivars. The pulps presented high concentrations of oleic acid. In addition, peel and seeds presented lower omega-6/omega-3 ratios than the pulp. There was also a considerable amount of tocopherol in the peel and seeds, especially in Hass peel (230.7 mg/100 g). According to the results, the peel and seeds of avocado that are considered byproducts, can be utilized in food industry

Temperature inversion symmetry in the Casimir effect with an antiperiodic boundary condition

We present explicitly another example of a temperature inversion symmetry in the Casimir effect for a nonsymmetric boundary condition. We also give an interpretation for our result.Comment: 4 page

Consumers’ willingness to purchase three alternatives to meat proteins in the United Kingdom, Spain, Brazil and the Dominican Republic

One of the current trends in dietary preferences involves the transition to a low- or reduced-meat diet, which is often desirable for health and environmental reasons. This change in dietary preferences requires an in-depth insight into consumers’ preferences towards a variety of alternative/non-meat proteins. This study aimed to investigate the consumers’ preferences and willingness to purchase three alternative dietary protein sources, namely plant-, cultured meat- and insect-based proteins in four countries with dissimilar economic development status (the United Kingdom, Spain, Brazil and the Dominican Republic). It also aimed to determine which factors would most influence the willingness to purchase. From a total sample of 729 valid respondents, psychographic variables were analysed. The alternative protein deemed the respondents’ most preferred willing to purchase was the plant-based type since that option tended to be more widely available in the market. Among the analysed economic groups, the countries classified in the higher economic groups tended to show more readiness to replace traditional meats for the three alternatives. Models suggest that the respondents regarded the alternative characteristics and/or the attributes compared to meat as being the most important factors that influence their willingness to purchase rather than environmental, convenience or healthy buying decisions, or a low level of neophobia. If the perception of healthiness, safety and nutritiousness increases one-unit for the cultured meat in Brazil, the probability of willingness to purchase would increase 86.82%. One-unit stronger belief in Spanish that plant-based are healthy, safe and nutritious higher the probability of willingness to purchase 68.74%. One-unit higher perceive the characteristics of healthiness, safety and nutritional content of the insects-based products would increase 68% the probability of willingness to purchase in the United Kingdom, 72% in Brazil and 58% in the Dominican Republic

Comparison between spectral analysis and symbolic dynamics for heart rate variability analysis in the rat

Spectral analysis of heart rate (HR) has been widely used to assess the autonomic cardiovascular control. A nonlinear approach, known as symbolic analysis, has been reported to be very useful to assess the autonomic control of cardiovascular system in humans, but very few studies reported on the differences between these two approaches on experimental models. Two distinct approaches were used to elicit autonomic changes in conscious Wistar rats: (1) pharmacological blockade of cardiac autonomic receptors with atenolol (ATE, N\u2009=\u20099) or methylatropine (ATR, N\u2009=\u20099) and (2) mild changes in arterial pressure (AP) induced by phenylephrine (PHE, N\u2009=\u20099) or sodium nitroprusside (NPS, N\u2009=\u20099). Series of cardiac interval (CI) and systolic AP (SAP) were assessed using spectral analysis and symbolic dynamics. Results show that, for spectral analysis, the power in high frequency band of CI and the power in low frequency band of SAP are the most reliable indices of vagal and sympathetic modulation, respectively. For symbolic analysis, results point 0V% and 1V% to be related to sympathetic and 2UV% to vagal modulation. Interestingly, the incidence of 1V patterns, hitherto with unknown meaning, was revealed the best index of sympathetic modulation in the rat and should be accounted for in the future studies

Hopf algebras and Markov chains: Two examples and a theory

The operation of squaring (coproduct followed by product) in a combinatorial Hopf algebra is shown to induce a Markov chain in natural bases. Chains constructed in this way include widely studied methods of card shuffling, a natural "rock-breaking" process, and Markov chains on simplicial complexes. Many of these chains can be explictly diagonalized using the primitive elements of the algebra and the combinatorics of the free Lie algebra. For card shuffling, this gives an explicit description of the eigenvectors. For rock-breaking, an explicit description of the quasi-stationary distribution and sharp rates to absorption follow.Comment: 51 pages, 17 figures. (Typographical errors corrected. Further fixes will only appear on the version on Amy Pang's website, the arXiv version will not be updated.

Analysis of the influence of the different times of polymerization by incandescent light in composite resins by evaluation of its abrasive wear

No mercado atual a qualidade é necessária na fabricação dos produtos. No mercado odontológico, as resinas compostas são cada vez mais utilizadas para substituir materiais tradicionais, como amalgama, nas restaurações estéticas e funcionais, apresentando boa estética e funcionalidade. A composição química destes materiais é variável e os resultados das reações químicas do processo de polimerização são bastante desconhecidos. O objetivo deste trabalho era medir a resistência do desgaste abrasivo de seis resinas compostas vendidas no mercado brasileiro polimerizadas com tempos de 10, 20 e 40 segundos. O método do disco retificado modificado para aplicações em odontologia foi usado para tornar esta proposta viável. Neste banco de ensaios um disco dinâmico, revestido por porcelana, desgasta um disco estático revestido do tipo de resina que se pretende avaliar, que foi polimerizada durante um tempo pré-estabelecido. Com a determinação do desgaste de material, num determinado tempo, determinava-se a agressividade (capacidade de um material para desgastar outro material) do disco dinâmico sobre o disco estático. Utilizando-se para isso um programa computacional (LabView). Posteriormente era feita a regressão linear dos valores obtidos e determinado o coeficiente angular, utilizado no cálculo de agressividade. Valores elevados de agressividade indicam uma maior agressão do disco dinâmico contra o disco estático. Os resultados mostraram um comportamento variável para cada material que foi polimerizado nos diferentes tempos de polimerização utilizado, mostrando que o método para fazer estudos de desgaste é prático e rápido para testar materiais novos antes da sua utilização.1317787Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Não temIn the current market an increasing quality is demanded to manufacture products. At the odontologic market the composed resins are becoming more and more used to replace old materials, like amalgamates in the aesthetic and functional restorations, since they present a better appearance and easier manuscript. The chemical composition of these materials varies and the results of the chemical reactions of polymerization processes are quite unknown. The aim of this work was to measure the resistance of the abrasive wear of six composed resins sold in Brazilian market when displayed to polymerization periods of 10, 20 and 40 seconds. The grinding disc method appropriated for odontology was used to make this process possible. For this a bank of assays in which a porcelain covered dynamic disc consumes a static disc recovered by the polymerized resin is used to demonstrate the method in a pre-established time. The abrasive wear was determined by the calculation of the aggressiveness (capacity of a material to consume another). This aggressiveness is determined by an initial graph of displacement for time, through the computational method (LabView program). After they have passed through a linear regression the results give as a possibility the angular coefficient, considered a parameter at the calculation of aggressiveness. Higher values of aggressiveness which means a higher aggression suffered by the resin disc indicate worse resistance to the abrasive consuming of this resin in relation to porcelain. The results showed a variable comportment for each material ahead the different polymerization time, which prove the importance in create a practical and fast analyses method to test new materials before their us