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Journal articles on the topic "The Hoff test"
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Syaifulloh, Moh, Mujib Akhis Susanto, Minidian Fasitasari, Muhammad Aziz, Saras Pudjowati, Muhammad Fatah Yasin, and Rochady Setianto. "Efektivitas Terapi Metode Wim Hoff Terhadap Respirasi, Denyut Jantung, Dan SpO2 Pada Pasien Covid – 19 Di Rumah Sakit Islam Sultan Agung Semarang." Medica Hospitalia : Journal of Clinical Medicine 7, no. 1A (August 28, 2020): 171–75. http://dx.doi.org/10.36408/mhjcm.v7i1a.482.
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Latar belakang : Metode Wim Hoff merupakan kombinasi dari paparan dingin, tekhnik pernafasan, dan meditasi. Kombinasi antara terapi konvensional medis dengan terapi non farmakologis seperti pada Metode Wim Hoff yang berusaha mengkombinasikan antara yoga dengan pengaturan nafas sehingga memberi kesempatan pada peningkatan volume/kapasitas tidal paru menjadi stabil. Ada banyak variasi dari metode Wim Hoff meliputi mengontrol pernafasan, menahan nafas, dan memulai pernafasan, ketiga fase tersebut dapat diulang dalam kurun waktu tiga kali secara berturut – turut atau lebih. Dengan dilakukan terus menerus sangat membantu peningkatkan sel darah merah, meningkatkan kapasitas tidal paru, meningkatkan sirkulasi, dan dapat dibuktikan secara klinis. Penelitian ini bertujuan untuk mengetahui pengaruh Metode Wim Hoff terhadap pola nafas, denyut jantung, dan SpO2 pasien Covid – 19 yang dirawat di Rumah Sakit Islam Sultan Agung Semarang.
Metode : Metode yang digunakan dalam penelitian ini adalah quasi experiment dengan desain pre dan post test tanpa kelompok kontrol. Sampel pada penelitian ini dipilih secara consecutive, dan terdiri dari 25 responden dengan rincian 9 laki – laki dan 16 perempuan. Ditemukan hasil bermakna antara intervensi sebelum dan sesudah terhadap pola nafas, dan SpO2, selanjutnya data diolah menggunakan uji paired T test dampak komparatif Wim Hoff dengan perbandingan respirasi, denyut jantung, SpO2 dan uji Wilcoxon signed rank test pada kelompok perlakuan didapatkan P = 0,0014 < ? = 0,05, sehingga H0 ditolak. Pada kelompok kontrol didapatkan P = 1,000 > ? = 0,05 sehingga H0 diterima, artinya bahwa ada pengaruh terhadap kemandirian responden kelompok perlakuan.
Hasil : Hasil uji statistik adalah p value 0,000 pada pola nafas dan SpO2, akan tetapi terhadap denyut jantung didapatkan p value 0,447.
Simpulan : Metode Wim Hoff mampu menstabilkan pola nafas dan SpO2, akan tetapi tidak untuk denyut jantung.
Kata kunci : Wim Hoff, Pola nafas, SpO2, Denyut jantung
Background : Wim Hof Method (WHM) is combination of frequent cold exposure, breathing techniques and meditation. The combination of conventional medical therapy with non-pharmacological therapies such as the Wim Hoff Method which seeks to combine yoga with breath control so as to provide an opportunity for the increase in lung tidal volume / capacity to become stable.There are many types of breathing method including Controlled breathing, Breath retention, and Recovery. these three phases may be repeated for three or more consecutive rounds. By being done continuously it really helps increase red blood cells, increase lung tidal capacity, improve circulation, and can be proven clinically. This research aimed to explore the effect of Wim Hoff Method on respiration rate, heart rate, and SpO2 among Covid – 19 patients at Islamic Sultan Agung Hospital Semarang.
Methods : Quasi experiment used in this study was pre and post test design without control group. Sampel were recruited using consecutive sampling. The samples of this study consists of 25 Covid – 19 patients including 9 male and 16 female. The study found significant result between pre and post test intervention for respiration rate and SpO2. A meaningful result between the before and after intervention of the breath pattern, and the SpO2, subsequently the data was processed using a test paired T comparative impact of Wim Hoff with a ratio of respiration, heart rate, SpO2 and a test of Wilcoxon signed rank test on the treatment group obtained P = 0.0014 < ? = 0.05, so that H0 rejected. In the control group acquired P = 1.000 > ? = 0.05 so that H0 was accepted, meaning that there was an influence on the self-reliance of the group treatment.
Result : The statistical test result was p value 0,000 for respiration rate and SpO2 but for the heart rate p value 0,447.
Conclusion : Wim Hoff Method was effective on stabilizing respiration rate and increasing SpO2 but not for heart rate.
Keyword : Wim Hoff Method, Respiration rate, SpO2, Heart rate.
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Karabağ, S., and Z. Taş. "The examination of the effect of caffeine supplementation in professional soccer players." Physical education of students 23, no. 3 (May 24, 2019): 129–41. http://dx.doi.org/10.15561/20755279.2019.0304.
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Purpose: In this study, the effects of caffeine supplementation in professional soccer players on the Hoff and sprint tests were examined. Material: 11 professional soccer players participated in this study in line with this purpose (Xage=20.636). The Hoff and sprint tests were applied 3 times at 1 week intervals. In each of these practices, caffeine added water was performed on the participants in the first week, and placebo was performed in the second week. In the third week, the participants were tested without any additional supplement. This practice lasted 3 weeks. Caffeine supplementation was given to each participant with the amount of 6 mg / kg in 200 ml water 1 hour before the tests, and placebo supplementation in 200 ml water was given 1 hour before the tests. The soccer players did the hoff test and sprint test respectively after 20 minutes of warming period. Results: Following Wilcoxon signed-ranks analysis, it was found that caffeine supplementation and placebo applications significantly increased the hoff test averages (p <0.05), while sprint test averages were reduced significantly in statistical terms (p <0.05). Conclusions: As a conclusion, we can state that caffeine application significantly increased the hoff test averages in comparison to placebo (p <0.05), and that it caused sprint test averages to decrease significantly in statistical terms (p <0.05).
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Kostelis, Kimberly, and Jason Melnyk. "Comparison of Beep Test and Hoff Test for VO2max Estimation Among Soccer Players." Medicine & Science in Sports & Exercise 47 (May 2015): 968–69. http://dx.doi.org/10.1249/01.mss.0000479371.84745.5f.
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RAMIREZ, JHON F., Henry H. León-Ariza, Alveiro Sánchez-Jiménez, Natalia Mejia-Serrano, and Nahala F. Aborashed-Amador. "Hoff Test Validity In Soccer Players Trained At 2600 Meters Above Sea Level." Medicine & Science in Sports & Exercise 48 (May 2016): 795. http://dx.doi.org/10.1249/01.mss.0000487383.14453.3b.
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Zart, Sebastian, Stephan Becker, and Michael Fröhlich. "A Syrup–Water Mixture Increases Performance in the Yo-Yo Intermittent Recovery Test after a Soccer-Specific Preload in the Hoff Test: A Double-Blind Crossover Study." Beverages 7, no. 2 (April 20, 2021): 20. http://dx.doi.org/10.3390/beverages7020020.
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Background: The positive effect of carbohydrates from commercial beverages on soccer-specific exercise has been clearly demonstrated. However, no study is available that uses a home-mixed beverage in a test where technical skills were required. Methods: Nine subjects participated voluntarily in this double-blind, randomized, placebo-controlled crossover study. On three testing days, the subjects performed six Hoff tests with a 3-min active break as a preload and then the Yo-Yo Intermittent Running Test Level 1 (Yo-Yo IR1) until exhaustion. On test days 2 and 3, the subjects received either a 69 g carbohydrate-containing drink (syrup–water mixture) or a carbohydrate-free drink (aromatic water). Beverages were given in several doses of 250 mL each: 30 min before and immediately before the exercise and after 18 and 39 min of exercise. The primary target parameters were the running performance in the Hoff test and Yo-Yo IR1, body mass and heart rate. Statistical differences between the variables of both conditions were analyzed using paired samples t-tests. Results: The maximum heart rate in Yo-Yo IR1 showed significant differences (syrup: 191.1 ± 6.2 bpm; placebo: 188.0 ± 6.89 bpm; t(6) = −2.556; p = 0.043; dz = 0.97). The running performance in Yo-Yo IR1 under the condition syrup significantly increased by 93.33 ± 84.85 m (0–240 m) on average (p = 0.011). Conclusions: The intake of a syrup–water mixture with a total of 69 g carbohydrates leads to an increase in high-intensive running performance after soccer specific loads. Therefore, the intake of carbohydrate solutions is recommended for intermittent loads and should be increasingly considered by coaches and players.
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Zagatto, Alessandro Moura, Willian Eiji Miyagi, Gabriel Motta Pinheiro Brisola, Fabio Milioni, Adelino Sanchez Ramos da Silva, Paulo Roberto Pereira Santiago, and Marcelo Papoti. "Correlation between Hoff test performance, body composition and aerobic and anaerobic fitness in professional soccer players." Sport Sciences for Health 11, no. 1 (October 19, 2014): 73–79. http://dx.doi.org/10.1007/s11332-014-0210-0.
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Zagatto, Alessandro, Marcelo Papoti, Adelino da Silva, Ricardo Barbieri, Eduardo Campos, Eliel Ferreira, João Paulo Loures, and Karim Chamari. "The Hoff circuit test is more specific than an incremental treadmill test to assess endurance with the ball in youth soccer players." Biology of Sport 33, no. 3 (May 3, 2016): 263–68. http://dx.doi.org/10.5604/20831862.1201913.
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Liu, Jing. "Thermodynamic Properties of Mg-Ni-H Compounds Prepared Assisted by a High Magnetic Field." Advanced Materials Research 739 (August 2013): 66–70. http://dx.doi.org/10.4028/www.scientific.net/amr.739.66.
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The Mg2NiH4 hydrogen storage material was prepared by magnetic field assisted combustion synthesis (MACS). It is found that the high magnetic field promotes the formation of Mg2NiH4. The high pressure differential scanning calorimetry (HPDSC) test results indicate that the optimum hydriding and dehydriding onset temperatures are 434 K and 525 K, respectively. However, the peak temperatures associated with LT à HT are similar for all samples. The Vant Hoff results show that a high magnetic field has no obvious effect on the entropies and enthalpies of these compounds.
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Pennington, Jamie, Bradley P. Wynne, and Glenn Byrne. "Constitutive Equation Development to Model the Hot Forging of ZERON®100 Super Duplex Stainless Steel and Associated Microstructural Evolution." Key Engineering Materials 716 (October 2016): 632–42. http://dx.doi.org/10.4028/www.scientific.net/kem.716.632.
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A constitutive equation of flow stress based on the Norton-Hoff equation has been developed for the high chromium and nitrogen containing super duplex stainless steel, ZERON® 100 (UNS S32760). This was then used to model, using the finite element method, the strain distribution within a uniaxial compression test under typical two-phase forging conditions. Predictions from the model were used to correlate deformation history to microstructure morphology. The microstructure consisted of austenite, γ islands (both primary and secondary) within a ferrite, δ matrix that contained chromium nitride precipitates. For deformation temperatures of 1050°C and 1120°C, the small secondary austenite was equiaxed, whilst at 1280°C the secondary austenite exhibited a Widmanstätten morphology. The highest level of nitride precipitation occurred at the highest deformation temperatures, i.e. highest volume fraction of ferrite, independent of strain rate. This suggests that nitride precipitation appears to be driven to a greater extent by thermal factors than deformation substructure.
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Wang, Wei, Haitao Luo, Jia Fu, Haochen Wang, Changshuai Yu, Guangming Liu, Qiming Wei, and Shufan Wu. "Comparative application analysis and test verification on equivalent modeling theories of honeycomb sandwich panels for satellite solar arrays." Advanced Composites Letters 29 (January 1, 2020): 096369352096312. http://dx.doi.org/10.1177/0963693520963127.
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Due to the difficulty of direct finite-element modeling for honeycomb sandwich panels, it is more common to apply equivalent modeling theories. It is necessary to compare their equivalent precision and then to determine the method with the best equivalent performance so as to prepare for the application in satellite solar arrays. The first 10 natural frequencies are obtained by analyzing the dynamic characteristics of sandwich panel theory model, honeycomb panel theory model, and equivalent panel theory model. The equivalent errors of different equivalent methods are obtained by comparison with the analysis results of real honeycomb panel model. Then, the sandwich panel theory and the Hoff theory with high precision are used to simulate the solar array panel. The two methods are further verified and compared by simulation and experiment. Finally, the sandwich panel theory with the highest accuracy is selected to simulate the vibration response of the solar array panel based on the above work. By comparing the frequency response analysis results with the test results, it is found that the maximum acceleration response error is within 7%, and the corresponding frequency error of the main direction is within 3%. The comparison between random analysis results and test results shows that the root mean square response errors of acceleration in three directions are within 13.7%. It is proved that the sandwich panel theory has high accuracy in the honeycomb structure. Based on the background of a specific space project, this study innovatively applies the test results to compare several typical equivalent theories of honeycomb sandwich panels so as to get a theory with the highest equivalent precision. The final conclusion has been applied to the design of related space products and proved to be feasible. This provides important reference and basis for the structural design of the satellite.
Dissertations / Theses on the topic "The Hoff test"
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Edlund, Elin, and Robert Wiik. "Hur korrelerar GIH:s Pyramidtest med VO2max på rullband för elitorienterare?" Thesis, Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:gih:diva-1784.
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Syfte och frågeställningar Syftet med studien var att undersöka för elitorienterare resultaten vid och korrelationen mellan ett så kallat 5 minuters pyramidtest (5MPT) och ett maximalt test för bestämning av maximalt syreupptag (VO2max) på rullband. Frågorna vi ställde oss var: Vilken korrelation föreligger mellan 5MPT och ett bestämt VO2max på rullband hos elitorienterare? Hur ser en jämförelse ut mellan uppmätt samt beräknat VO2max? Vilken är reliabiliteten för 5MPT? Hur ser ekvationen ut för att beskriva sambandet mellan dessa två olika maxtester? Metod I valideringsstudien deltog 16 elitorienterare (6 kvinnor och 10 män) i åldrarna 17 till 37 år. De två testerna som genomfördes var 5MPT och bestämning av VO2max på rullband. 5MPT är ett skytteltest som är fem minuter långt, där testpersonen (tp) tar sig fram och tillbaka mellan två stolpar (sträcka 5.5 m) där en vertikal trappa (formad likt en pyramid) passeras under varje vända. Antalet vändor, skattad ansträngning samt hjärtfrekvens (HF) registrerades. Utvecklad power (effekt) erhölls genom produkten av vikt, gravitation, antal vändor, höjd på högsta plinten (0,62 m) dividerat med total duration i 5MPT. Testet för att bestämma VO2max utfördes med löpning på ett motordrivet rullband. Under den första minuten av testet sprang tp på en hastighet av 8km/h (kvinnor) respektive10km/h (män) utan lutning. För varje minut ökades hastigheten med 1km/h. Lutningen höjdes med en grad efter minut ett och därefter med 0,5 grader/minut. Testet pågick till dess tp nått sin VO2max. Var 15:e sekund registrerades tp:s HF, VO2 (l/min), VCO2 (l/min), VO2 (ml/kg/min) och respiratorisk kvot (RER) med hjälp av ett datoriserat syreupptagningssystem. Resultat Korrelationen var signifikant och hög (r = 0,89, p<0,0001) mellan utvecklad power på 5MPT och VO2max (l/min) och även mellan antalet vändor på 5MPT och VO2max (l/min) (r = 0,89, p<0,0001) på detta material av elitorienterare. Följande formler, baserade på resultaten från elitorienterarna, kan användas för att predicera VO2max efter genomfört 5MPT: VO2max (l/min) = (5MPTPOWER – 50,914) / 25,795 VO2max (l/min) = (5MPTVÄNDOR – 74,447) / 9,7668 Slutsats 5MPT uppvisar en stark korrelation med bestämd VO2max sett till power och/eller antalet genomförda vändor. Beräkningsformler för prediktion av VO2max har varit möjligt att beskriva. Se resultatdelen för andra resultat och samband mellan 5MPT och VO2max.Abstract Aim The aim of this study was to investigate for elite orienteers the results in and the correlation between a so called 5-minutes-pyramid test (5MPT) and a specific maximum oxygen uptake test (VO2max) on a treadmill. The questions we asked ourselves were: Which correlation exists between 5MPT and a specific VO2max on the treadmill for elite orienteers? How would a comparison look like between measured and estimated VO2max? What is the reliability for the 5MPT? How would an equation look like that describe the correlation above? Method In the validity the study 16 elite orienteers (6 women and 10 men) aged 17 to 37 years participated. The two tests that have been carried out were the 5MPT and determined VO2max during running on a treadmill. The 5MPT is a 5-minute-shuttle test, in which the participant moves back and forth in a short interval (5.5 m) over boxes (highest height: 0.62) formed like a pyramid. Power in the pyramid test (5MPTPOWER) was calculated as the product of numbers of laps, body weight, gravity and highest box level divided by time. To determine VO2max the method running on a treadmill was performed. During the first minute the running speed was 8km/h (women)/10 km/h (men) without elevation. Each minute the velocity increased with 1 km/h. The elevation increased with 1 degree after the first minute and thereafter with 0,5 degrees/minute. The test was finished when the participant had reached her VO2max. Every 15 second the participants heart rate, VO2 (l/min), VCO2 (l/min), VO2 (ml/kg/min) and RER, was registered by means of an online system. Results The correlation between the developed power of the 5MPT and measured VO2max (l/min) was high (r = 0.89, p<0,0001) and also between the number of laps in the 5MPT and measured VO2max (l/min) (r = 0.89, p < 0,0001). The following formulas can be used to predict VO2max after completed 5MPT: VO2max (l/min) = (5MPTPOWER – 50,914) / 25,795 VO2max (l/min) = (5MPTLAPS – 74,447) / 9,7668 Conclusions 5MPT show a strong correlation with VO2max determined in terms of power and/or the number of completed laps. Calculated formulas for prediction of VO2max have been possible to describe. See results section for other results and relationships between 5MPT and VO2max.
Maximal Aerobic Power versus Performance in Two Aerobic Endurance Tests among Young and Old Adults.Andersson E, Lundahl N, Wecke L, Lindblom I, Nilsson, J.
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García, Cabrera Miguel. "Structural Material Investigation of Horse Hoof." Thesis, Högskolan i Skövde, Institutionen för teknik och samhälle, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-8309.
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This research focuses on a study of the material parameters of horse hoof. The study of the problem with the factors that affect to the fastening of the shoe is not performed. Three different tests are carried out to obtain the behavior of the horn wall of the horse hoof in different ways, under physiological conditions and variation of hydration level. The first one is a tensile test to obtain both the force/displacement relation and the stress/strain relation and the parameters derived from them. The second is a hardness test to determine how the material resists to several kinds of permanent-shape changes when a force is applied.Finally, a microscopic study is performed to analyze the fracture surface after testing the specimens. A meticulous analysis of the results and a broad comparison with several researches are performed. The end of the thesis work suggests future works needed to solve the problem.
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Assis, Bruno Moraes. "Histomorfometria, microtomografia bidimensional e tridimensional, teste de nanodureza e composição bioquímica do estojo córneo de bubalinos." Universidade Federal de Goiás, 2015. http://repositorio.bc.ufg.br/tede/handle/tede/5132.
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Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
Despite not being a common subject of studies about buffalo, the incidence of hulls diseases has important scientific aspects as these animals, as they are breeded in adverse conditions, have different resistance for the occurrence of podais diseases when compared to cattle, especially dairy cattle. The knowledge about microstructural structures of buffalo’s hoof generated important information for understanding of the intrinsic resistance of buffaloes foot diseases. This study aimed to investigate the microstructure of adult Jafarabadi buffaloes, through histomorphometric ratings, two-dimensional microtomography, three-dimensional, nanohardness test and biochemical composition. Histomorphometric ratings revealed important features not yet investigated by other researchers, highlighting the structural behavior of epidermal papillae in different regions of corneal layer, the morphology and disposition of the horn tubules, the architecture of extratubular and intratubular keratin and even organization of melanosomes . It was observed that the average length of buds, thickness and spacing in pelvic and thoracic digit did not show statistically significant differences. However, an increase in thickness of the laminar corium papillae of the wall and spacing was observed when comparing the average of the coronary corium and wall and sole laminar corium. When compared to the findings of other researchers, this study have shown that the epidermal papillae on the hulls of these animals are presented larger than the epidermal papillae of Holstein and Gir animals, suggesting that the buffalo’s has greater keratin production and better epidermis and horny case fixing. It can be conjectured that such characteristics are associate with greater resistance to foot diseases of this animals, although additional studies are needed. Analysis of microtomography and nanohardness test showed increased medial digit of forelimbs and side-digit of hindlimbs exhibit increased horn tubules with larger diameters. But the abaxial wall of forelimbs digit showed higher values than hindlimbs digit. Even there was not significant difference between the digits analyzed, this study could clarify important aspects of the nanohardness of different regions of the corneal case of buffalo’s digits. 3D microtomography analysis revealed that the dorsal wall presents a greater hardness compared to the abaxial wall of intermediate hardness, and with the sole of the hoof, that showed the lowest hardness among the evaluated areas. It was inferred that tridimensional microtomography testing is more specific than Vickers nanohardness test for this structure. However, further research are required. Biochemical tests generated parameters about structural elements of the corneal case, which showed different concentrations in relation to the region and anatomical position of the hull. These differences are related to the digits wich recive higher load of body weight and impact. This study generated knowledge and parameters to be used in further researches on different bovine species and breeds.
As enfermidades de cascos, apesar de ser alvo de poucos estudos na espécie bubalina, apresentam aspectos científicos importantes uma vez que estes animais, mesmo criados em condições adversas, apresentam resistência diferenciada quanto à ocorrência de doenças podais, quando comparados aos bovinos, com destaque para os de aptidão leiteira. Acredita-se que o conhecimento microestrutural do casco de bubalinos gerou informações importantes para melhor entendimento da resistência podal intrínseca dos bubalinos às enfermidades podais. O presente estudo teve por finalidade pesquisar a microestrutura do estojo córneo de búfalas adultas, raça Jafarabadi, por meio de avaliações histomorfométricas, microtomografia bidimensional, tridimensional, teste de nanodureza e composição bioquímica. As avaliações histomorfométricas em bubalinos revelaram características importantes ainda não investigadas por outros pesquisadores, destacando o comportamento estrutural das papilas epidérmicas nas diferentes regiões do estojo córneo, a morfologia e disposição dos túbulos córneos, a arquitetura da queratina extratubular e intratubular e ainda organização dos melanossomas. Pode-se observar nessas avaliações que as médias de comprimento das papilas, espessura e espaçamento nos dígitos dos membros pélvicos e torácicos não apresentaram diferenças estatísticas significativas entre si. Todavia, ao comparar as médias do córion coronário, córion laminar da muralha e sola, observou-se entre as regiões do estojo córneo, um aumento da espessura das papilas do córion laminar da muralha e do espaçamento comparando-se as demais regiões. Os achados dessa pesquisa quando comparados aos achados de outros pesquisadores, demonstraram que as papilas epidérmicas nos cascos desses animais, apresentam-se maiores que as papilas epidérmicas de bovinos das raças, Holandesa e Gir, sugerindo que possuem maior capacidade de produção de queratina e melhor fixação da epiderme ao estojo córneo. Contudo, pôde-se conjecturar tais características com a maior resistência desses animais as enfermidades podais, embora haja a necessidade de estudos adicionais. Por meio das análises de microtomografia e teste de nanodureza, pode-se verificar que os dígitos mediais dos membros torácicos e os dígitos laterais dos membros pélvicos apresentaram maior quantidade de túbulos córneos com diâmetros maiores. Porém, a muralha abaxial dos dígitos dos membros torácicos apresentaram valores superiores aos dígitos dos membros pélvicos. Apesar de não ter sido observada diferença significativa entre os dígitos estudados, o presente estudo pôde esclarecer, ainda, aspectos importantes sobre a nanodureza das diferentes regiões do estojo córneo dos dígitos de bubalinos. A análise de microtomografia 3D revelou que a muralha dorsal apresenta maior dureza quando comparada com a muralha abaxial, de dureza intermediária, bem como, com a sola do casco, que apresentou menor dureza entre as regiões avaliadas. Inferiu-se assim que o teste de microtomografia tridimensional seja mais específico que o teste de nanodureza de Vickers para a estrutura considerada. No entanto, tal afirmação requer pesquisas adicionais. Os testes bioquímicos geraram parâmetros quanto aos elementos estruturais do estojo córneo, que demonstraram diferentes concentrações em relação à região e posição anatômica do casco, sendo essas diferenças associadas aos dígitos que recebem maior sobrecarga de massa corporal e impacto. O presente estudo gerou conhecimento e parâmetros a serem utilizados em outras investigações científicas, em outras espécies e raças de bovídeos.
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Caldwell, M. N. "An investigation into the use of hoof balance metrics to test the reliability of a commonly used foot trimming protocol and their association with biomechanics and pathologies of the equine digit." Thesis, University of Liverpool, 2017. http://livrepository.liverpool.ac.uk/3012434/.
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The equine foot has a specific conformation (shape) that provides maximum biomechanical efficiency. Biomechanical efficiency allows the foot to withstand, accept, absorb, dissipate and transmit loading weight bearing forces in a manner that offers the greatest protection to the horse. This principle implies that there is some combination of foot size, foot shape, wall length and angles that make the foot an ideal shock absorbing, weight-bearing structure. It is the proper combination of these variables are said to constitute what has been described as the properly balanced foot. However, there are currently several conflicting hoof balance reference systems commonly utilised and what constitutes ideal balance has been the subject of great debate for many years. One goal of the research was to investigate the principle of equal geometric proportions and dependentcy on factors such as foot-type and environmental conditions. By utilising a standardised trimming protocol and a hoof mapping system to collect measurement data based on proportionality of the bearing border length the purpose of this study was, partly, to verify whether a commonly used theory of hoof balance, firstly described by Duckett, is achieved. Secondly to determine whether geometric proportions are equivalent following trimming, thereby achieving hoof balance. Analysis suggested Currently accepted interpretations of static hoof balance including the achievement of an aligned phalangeal axis and a ground bearing border bisected by CoR are likely to be outmoded. This provides support to the hypothesis that feet should be managed on an individual basis rather than a “one-size fits-all” approach commonly applied and that implementing a prescriptive model may even be counter-productive to the functional integrity of the hoof. Farriery technique have been shown to influence skeletal alignment within the foot. Standardised trimming and shoeing protocols were used to test the hypothesis that shoeing, over an extended period of time, would result in significant differences in static hoof balance proportions. Results showed that horses managed unshod had greater ability to manipulate bearing border length, re-align the heel angle and allow palmar heel migration than shod horses. Furthermore, proportional hoof balance measures were able to be altered in unshod feet and that equivalence of the proportional hoof measures were not present in either cohort (unshod/shod). The significant differences in hoof measures present in shod feet ie; flattening of the sole, heel contraction, reduction in dorsal hoof wall and heel angulation and dorsal migration of dorsal hoof wall and heel seemed likely to reflect the effect of the shoe over an extended period. The application of a standard steel horseshoe appeared to influence hoof shape and is likely to both affect and be affected by mechanical forces acting on the foot. The affect of hoof shape and the mechanical forces experienced by the foot itself following the application of the standardised trimming protocol and the application of a shoe were investigated. Results highlighted significant post-shoeing statistical differences in all dynamic measurements between shod and unshod feet. Specifically post-shoeing reductions in peak pressure and the contact area resulting in differences in peak force and peak force time were noted. These results partially support the propersition of a difference in mechanical behavior of the foot under load and may reflect the differences witnessed in feet under different management regimes. Biomechanical analyses of this kind enable improved understanding of hoof function, and a rational, objective basis for comparing the efficacy of different therapeutic strategies designed to address hoof dysfunction and pathology. There is considerable anecdotal information that poor foot conformation and balance are associated with an increased risk of foot-related lameness but foot imbalance may also result from lameness as an adaptation to chronic pain. Utilising MRI findings from a group of horses referred for lameness investigation bionominal logistic regression was used to test the hypothesis of risk of lameness associated with hoof measurement proportions. There is evidence to suggest a strong correlation between hoof conformation and the biomechanical inference on anatomical structures and foot-related pathologies. Variation in key hoof measurement proportions resulted in significant differences in risk factors of specific common foot pathologies ie; navicular disease and degenerative joint disease of the distal interphalangeal joint. It has been argued that the form of the solar arch was indicative the pathologies. Results from the current study appear to support his hypothesis by linking hoof morphology to the incidence of disease. Whilst the author recognises that hoof shape is influenced by any number of other factors, proportional values along the solar axis may well prove to be a good model for biomechanical efficiency either by trimming alone or form the basis of a more biomechanically sympathetic standardised shoeing model.
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Urbano, Simone. "Detection and diagnostic of freeplay induced limit cycle oscillation in the flight control system of a civil aircraf." Thesis, Toulouse, INPT, 2019. http://www.theses.fr/2019INPT0023/document.
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Cette étude est le résultat d’une thèse CIFRE de trois ans entre le bureau d’étude d’Airbus (domaine du contrôle de l’avion) et le laboratoire TéSA à Toulouse. L’objectif principal est de proposer, développer et valider une solution logicielle pour la détection et le diagnostic d’un type spécifique de vibrations des gouvernes de profondeur et direction, appelée oscillation en cycle limite (limit cycle oscillation ou LCO en anglais), basée sur les signaux existants dans les avions civils. LCO est un terme mathématique générique définissant un mode périodique indépendant de conditions initiales et se produisant dans des systèmes non linéaires non conservatifs. Dans cette étude, nous nous intéressons au phénomène de LCO induit par les jeux mécaniques dans les gouvernes d’un avion civil. Les conséquences du LCO sont l’augmentation locale de la charge structurelle, la dégradation des qualités de vol, la réduction de la durée de vie de l’actionneur, la dégradation du confort du poste de pilotage et de la cabine, ainsi que l’augmentation des coûts de maintenance. L’état de l’art en matière de détection et de diagnostic du LCO induit par le jeu mécanique est basé sur la sensibilité du pilote aux vibrations et sur le contrôle périodique du jeu sur les gouvernes. Cette étude propose une solution basée sur les données (issues de la boucle d’asservissement des actionneurs qui agissent sur les gouvernes) pour aider au diagnostic du LCO et à l’isolement du jeu mécanique. L’objectif est d’améliorer encore plus la disponibilité des avions et de réduire les coûts de maintenance en fournissant aux compagnies aériennes un signal de contrôle pour le LCO et les jeux mécaniques. Pour cette raison, deux solutions algorithmiques pour le diagnostic des vibrations et des jeux ont été proposées. Un détecteur en temps réel pour la détection du LCO est tout d’abord proposé basé sur la théorie du rapport de vraisemblance généralisé (generalized likelihood ratio test ou GLRT en anglais). Certaines variantes et simplifications sont également proposées pour satisfaire les contraintes industrielles. Un détecteur de jeu mécanique est introduit basé sur l’identification d’un modèle de Wiener. Des approches paramétrique (estimateur de maximum de vraisemblance) et non paramétrique (régression par noyau) sont explorées, ainsi que certaines variantes des méthodes non paramétriques. En particulier, le problème de l’estimation d’un cycle d’hystérésis (choisi comme la non-linéarité de sortie d’un modèle de Wiener) est abordé. Ainsi, les problèmes avec et sans contraintes sont étudiés. Une analyse théorique, numérique (sur simulateur) et expérimentale (données de vol et laboratoire) est réalisée pour étudier les performances des détecteurs proposés et pour identifier les limitations et la faisabilité industrielle. Les résultats numériques et expérimentaux obtenus confirment que le GLRT proposé (et ses variantes / simplifications) est une méthode très efficace pour le diagnostic du LCO en termes de performance, robustesse et coût calculatoire. D’autre part, l’algorithme de diagnostic des jeux mécaniques est capable de détecter des niveaux de jeu relativement importants, mais il ne fournit pas de résultats cohérents pour des niveaux de jeu relativement faibles. En outre, des types d’entrée spécifiques sont nécessaires pour garantir des résultats répétitifs et cohérents. Des études complémentaires pourraient être menées afin de comparer les résultats de GLRT avec une approche Bayésienne et pour approfondir les possibilités et les limites de la méthode paramétrique proposée pour l’identification du modèle de WienerThis research study is the result of a 3 years CIFRE PhD thesis between the Airbus design office(Aircraft Control domain) and TéSA laboratory in Toulouse. The main goal is to propose, developand validate a software solution for the detection and diagnosis of a specific type of elevator andrudder vibration, called limit cycle oscillation (LCO), based on existing signals available in flightcontrol computers on board in-series aircraft. LCO is a generic mathematical term defining aninitial condition-independent periodic mode occurring in nonconservative nonlinear systems. Thisstudy focuses on the LCO phenomenon induced by mechanical freeplays in the control surface ofa civil aircraft. The LCO consequences are local structural load augmentation, flight handlingqualities deterioration, actuator operational life reduction, cockpit and cabin comfort deteriorationand maintenance cost augmentation. The state-of-the-art for freeplay induced LCO detection anddiagnosis is based on the pilot sensitivity to vibration and to periodic freeplay check on the controlsurfaces. This study is thought to propose a data-driven solution to help LCO and freeplaydiagnosis. The goal is to improve even more aircraft availability and reduce the maintenance costsby providing to the airlines a condition monitoring signal for LCO and freeplays. For this reason,two algorithmic solutions for vibration and freeplay diagnosis are investigated in this PhD thesis. Areal time detector for LCO diagnosis is first proposed based on the theory of the generalized likeli hood ratio test (GLRT). Some variants and simplifications are also proposed to be compliantwith the industrial constraints. In a second part of this work, a mechanical freeplay detector isintroduced based on the theory of Wiener model identification. Parametric (maximum likelihoodestimator) and non parametric (kernel regression) approaches are investigated, as well as somevariants to well-known nonparametric methods. In particular, the problem of hysteresis cycleestimation (as the output nonlinearity of a Wiener model) is tackled. Moreover, the constrainedand unconstrained problems are studied. A theoretical, numerical (simulator) and experimental(flight data and laboratory) analysis is carried out to investigate the performance of the proposeddetectors and to identify limitations and industrial feasibility. The obtained numerical andexperimental results confirm that the proposed GLR test (and its variants/simplifications) is a very appealing method for LCO diagnostic in terms of performance, robustness and computationalcost. On the other hand, the proposed freeplay diagnostic algorithm is able to detect relativelylarge freeplay levels, but it does not provide consistent results for relatively small freeplay levels. Moreover, specific input types are needed to guarantee repetitive and consistent results. Further studies should be carried out in order to compare the GLRT results with a Bayesian approach and to investigate more deeply the possibilities and limitations of the proposed parametric method for Wiener model identification
Books on the topic "The Hoff test"
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Heunen, Chris, and Jamie Vicary. Categories for Quantum Theory. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198739623.001.0001.
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Monoidal category theory serves as a powerful framework for describing logical aspects of quantum theory, giving an abstract language for parallel and sequential composition and a conceptual way to understand many high-level quantum phenomena. Here, we lay the foundations for this categorical quantum mechanics, with an emphasis on the graphical calculus that makes computation intuitive. We describe superposition and entanglement using biproducts and dual objects, and show how quantum teleportation can be studied abstractly using these structures. We investigate monoids, Frobenius structures and Hopf algebras, showing how they can be used to model classical information and complementary observables. We describe the CP construction, a categorical tool to describe probabilistic quantum systems. The last chapter introduces higher categories, surface diagrams and 2-Hilbert spaces, and shows how the language of duality in monoidal 2-categories can be used to reason about quantum protocols, including quantum teleportation and dense coding. Previous knowledge of linear algebra, quantum information or category theory would give an ideal background for studying this text, but it is not assumed, with essential background material given in a self-contained introductory chapter. Throughout the text, we point out links with many other areas, such as representation theory, topology, quantum algebra, knot theory and probability theory, and present nonstandard models including sets and relations. All results are stated rigorously and full proofs are given as far as possible, making this book an invaluable reference for modern techniques in quantum logic, with much of the material not available in any other textbook.
Book chapters on the topic "The Hoff test"
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Werner, Bodo. "Test Functions for Bifurcation Points and Hopf Points in Problems with Symmetries." In Bifurcation and Symmetry, 317–27. Basel: Birkhäuser Basel, 1992. http://dx.doi.org/10.1007/978-3-0348-7536-3_28.
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Böttcher, Albrecht, Sergei Grudsky, and Arieh Iserles. "The Fox–Li Operator as a Test and a Spur for Wiener–Hopf Theory." In Essays in Mathematics and its Applications, 37–48. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-28821-0_3.
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Hoff, Molly. "9." In Virginia Woolf's Mrs. Dalloway: Invisible Presences. Liverpool University Press, 2018. http://dx.doi.org/10.5949/liverpool/9780979606670.003.0012.
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In this chapter, Hoff provides annotations on the ninth section of Mrs. Dalloway. She explores the book’s metanarrative and linguistic style whilst placing the text in the light of Greek literary tropes, and biblical and philosophical references. In this chapter, Hoff also provides the reader with a useful cultural context and re-touches on the book’s allusion to the previously discussed theory of the Butterfly Effect.
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Hoff, Molly. "12." In Virginia Woolf's Mrs. Dalloway: Invisible Presences. Liverpool University Press, 2018. http://dx.doi.org/10.5949/liverpool/9780979606670.003.0015.
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The final chapter concludes with a synopsis and analysis of the twelfth section of Mrs. Dalloway. Hoff supports her discussion of the action by unpacking the passage’s dialogue and linking key themes and symbols present in the novel to those found in Greek literature. The chapter ends with a mystical reading of Clarissa’s “rebirth”. Like the entirety of the text, the chapter recognises the presence of literary fragments scattered throughout the novel, and attempts to combine them all in order to produce a detailed discussion that is supplemented with Hoff’s own understanding of Greek literature.
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"A. Text Des RG." In Das sogenannte Religionsgespräch am Hof der Sasaniden, edited by Eduard Bratke, 1–45. Piscataway, NJ, USA: Gorgias Press, 2010. http://dx.doi.org/10.31826/9781463227609-001.
Full textConference papers on the topic "The Hoff test"
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Taka´cs, De´nes, and Ga´bor Ste´pan. "Nonlinear Oscillations at Critical Shimmy Parameters: Experiments and Numerics." In ASME 2010 International Mechanical Engineering Congress and Exposition. ASMEDC, 2010. http://dx.doi.org/10.1115/imece2010-38375.
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Brief description of a low degree of freedom shimmying wheel model is presented where the time delay effect is in the focus of the corresponding stretched-string-like tyre model. The stability charts obtained by linear stability analysis present various bifurcation phenomena. These are checked by experiments on a test rig and also by numerical simulations that involve the partial sliding of the tyre contact region as a nonlinear effect. The sense of the Hopf bifurcations are compared to various shimmy models including the classical single-contact-point ones. Double Hopf bifurcations leading to quasi-periodic oscillations are also investigated. The applied numerical methods are optimized for convergence and also for possible application in real-time control strategies.
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Nankali, Amir, Harsheeta Surampalli, Young S. Lee, and Tama´s Kalma´r-Nagy. "Suppression of Machine Tool Chatter Using Nonlinear Energy Sink." In ASME 2011 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/detc2011-48502.
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Suppression of regenerative instability in a single-degree-of-freedom (SDOF) machine tool model was studied by means of targeted energy transfers (TETs). The regenerative cutting force generates time-delay effects in the tool equation of motion, which retained the nonlinear terms up to the third order in this work. Then, an ungrounded nonlinear energy sink (NES) was coupled to the SDOF tool, by which biased energy transfers from the tool to the NES and efficient dissipation can be realized whenever regenerative effects invoke instability in the tool. Shifts of the stability boundary (i.e., Hopf bifurcation point) with respect to chip thickness were examined for various NES parameters. There seems to exist an optimal value of damping for a fixed mass ratio to shift the stability boundary for stably cutting more material off by increasing chip thickness; on the other hand, the larger the mass ratio becomes, the further the occurrence of Hopf bifurcation is delayed. The limit cycle oscillation (LCO) due to the regenerative instability appears as being subcritical, which can be (locally) eliminated or attenuated at a fixed rotational speed of a workpiece by the nonlinear modal interactions with an NES (i.e., by means of TETs). Three suppression mechanisms have been identified; that is, recurrent burstouts and suppressions, partial and complete suppressions of regenerative instabilities in a machine tool model. Each suppression mechanism was characterized numerically by time histories of displacements, and wavelet transforms and instantaneous energies. Furthermore, analytical study was performed by employing the complexification-averaging technique to yield a time-delayed slow-flow model. Finally, regenerative instability suppression in a more practical machine tool model was examined by considering contact-loss conditions.
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Prasse, K. W., J. N. Moore, and A. Duncan. "PROTEIN C ACTS AS AN ACUTE PHASE REACTANT IN EQUINE LAMINITIS." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643183.
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Equine Colic Syndrome is a disease of horses whose complications include laminatis.This term describes a situation where microvascular damage to the hoof causes degeneration of the interphalangeal laminae,leading to lameness. Vascular studies have suggested that microthrombosis involving the delicate vessels in the hoof,coupled with changes in the platelet count, coagulation factors & elevated FDP's implicate DIC as a potential etiology. Limited test capability in the horse has limited further evaluation of this hypothesis. We have developed an assay for equine protein C activity,our normal range being 70-60% (Mean+/- 2SD). We studied 12 horses with the disease for 5 consecutive days,drawing 1 blood sample per day. Our expectation was that protein C levels would decrease.if DIC was significant,as would be expected in humans. No significant decrease was noted in any horse. However there was a significant increase in the protein C levels beyond the upper limit of the normal range in 10 of the 12 horses by the third day. Five of the 10 horses maintained this elevation beyond the 5th day. Thus protein C changes were more consistent with an acute phase reactant response,rather than reflecting the decrease we anicipated,if the equine DIC parallels human DIC. We are measuring other acute phase reactants to see if equine protein C parallels those. Since our assay is still being evaluated,more data needs to be obtained in this and other equine disease states before any definative role for protein C in equine pathology can be determined. In our laminitis horses,we are devolping assays for antithrombin III and plasminogen which should allow us to evaluate the disease state more completley for any involement of elements of intravascular thrombosis and fibrinolysis in the equine colic syndrome.
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Nankali, Amir, Young S. Lee, and Tamas Kalmar-Nagy. "Targeted Energy Transfer for Suppressing Regenerative Instabilities in a 2-DOF Machine Tool Model." In ASME 2013 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/detc2013-13510.
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We study targeted energy transfer (TET) mechanisms by applying a nonlinear energy sink (NES) to suppress regenerative instabilities in a 2-DOF planar machine tool model. With the help of a numerical continuation tool, DDEBIFTOOL, we show that the tool instability is generated through a subcritical Hopf bifurcation in this simplified tool model. Studying modal energy exchanges reveals that only one of the DOFs is predominant, which may lead to the standard single-DOF machine tool model. Then, we apply an ungrounded NES to the 2-DOF tool model such that the NES interacts only with the dominant mode, which turns out to be more efficient than applying the NES to the other insignificant mode. Simple numerical simulations and bifurcation analysis demonstrate that the three typical TET mechanisms can be identified — That is, recurrent burstouts and suppression, and partial and complete suppression of tool instability.
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Villard, Paul, Samuel Nacivet, and Jean-Jacques Sinou. "Superelement Reduction of Industrial Finite Element Brake System for a Constrained Harmonic Balance Method." In ASME 2012 Noise Control and Acoustics Division Conference at InterNoise 2012. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/ncad2012-0484.
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Brake squeal is a ubiquitous disturbance in automotive systems. Facing the complexity and the cost of experimental tests, simulations of brake squeal have become essential as well as to provide a predictive numerical method. Two major approaches exist in the numerical analysis of this phenomenon, the transient analysis and the complex eigenvalue analysis. In this study, the Constrained Harmonic Balance Method is applied on an industrial finite element system in order to estimate the nonlinear stationary responses due to friction induced vibration. This paper aims at explaining how a finite element system was adapted to the CHBM and at analyzing the results. First of all, the method used to reduce a finite element brake system is examined and the contact issue is particularly emphasized. Then, a brief summary of the CHBM is made. Finally, limit cycles are obtained close to the Hopf bifurcation.
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Radhakrishnan, Anupam, Ben T. Edes, and Brian P. Mann. "An Experimental Study of Subcritical Bifurcations in Milling." In ASME 2007 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/detc2007-34808.
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The focus of the current paper is an experimental investigation of subcritical bifurcations in milling. Several researchers have reported results indicating that the secondary Hopf bifurcations of turning processes are subcritical. However, fewer results are available for milling — especially results that provide any substantial experimental evidence. Here, the experimental cutting tests were performed on a relatively long aluminum workpiece. The atypical length of the work piece will be used so that the depth of cut may be slowly increased or decreased during the cutting process. This provides visual evidence of hysteresis in the bifurcation diagram and the existence of multiple stable periodic solutions. The importance of this exploratory experimental effort is that multiple attractors may co-exist (stable periodic solutions) for the same cutting speed and depth of cut, but only one of these solutions would be the chatter free case. An important outcome from these results is that a small perturbation in the desirable stable solution near the borders of the stability diagram could result in a jump to the unstable cutting condition.
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Zhu, Tian-liang, Wei-jiang Xu, Xiao-yu Shi, Bo Su, and Fei Lu. "Experimental Study on Heat Transfer Characteristics of Array Impingement With Initial Cross-Flow." In ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-15139.
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Abstract In order to increase the thermal efficiency, combustion are designed to operate at higher temperature, which requires highly efficient cooling structures for combustion walls. Impingement is an effective structure to enhance the convective heat transfer in the combustion cooling. In the present study, two array impingement cooling structures with cross-flow are presented, and the heat transfer characteristics are obtained experimentally. The heat transfer performance of the impingement cooling structures are studied by using the transient liquid crystal thermography technique for turbulent flow in rectangular channels within the Reynolds number range from 75,000 to 125,000. The impingement hole diameters of the two test pieces were 12mm and 11mm, respectively. The impingement distances-to-hole diameter ratios (z/d) were 1.25 and 2, and the dimensionless hole spacing (x/d) was 2.5 and 2.727. It is found that crossflow shifts the jet downstream, resulting in asymmetric flow, the heat transfer coefficient upstream of the jet weakens, and the shape of stagnation area transitions from circular to hoof-shaped. The cross-flow disturbance accelerates the diffusion of the jet, which makes the distribution of the Nusselt number on the target more uniform, and the overall heat transfer on the target is enhanced. With the change of cross-flow intensity, there are differences in the influence of heat transfer on target under different impact geometries.
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Catania, Giuseppe, and Nicolo` Mancinelli. "Experimental Chatter Modeling of Milling Operations." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-41931.
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This study refers to the investigation on the critical operating condition occurring on high productivity milling machines, known as chatter. This phenomenon is generated by a self-excited vibration, associated with a loss of stability of the system, causing reduced productivity, poor surface finish and noise. This study consists of the theoretical and experimental modeling of machining chatter conditions, in order to develop a real-time monitoring system able to diagnose the occurrence of chatter in advance and to dynamically modify the cutting parameters for process optimization. A prototype NC 3-axis milling machine was ad hoc realized to accomplish this task. The machine was instrumented by a dynamometer table, and a series of accelerometer sensors were mounted in the proximity of the tool spindle and the workpiece. An analytical model was developed, taking into account the periodic cutting force arising during interrupted cutting operation in milling. The system dynamical behavior was described by means of a set of delay differential equations with periodic coefficients. The stability of this system was analyzed by the semi discretization approach based on the Floquet theory. Lobe stability charts were evaluated and associated with frequency diagrams. Two chatter types were analytically and experimentally detected: period-doubling bifurcations and secondary Hopf bifurcations. Measurement data were acquired and analyzed in the time and frequency domain. Several tests were conducted in a wide range of operating conditions, such as radial immersion, depth of cut and spindle speeds and using different tools. Results are reported showing agreement between the numerical analysis and the related experimental tests.
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Joyce, Bryan S., and Pablo A. Tarazaga. "Artificial Cochlear Hair Cells Using Active Piezoelectric Materials." In ASME 2013 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/smasis2013-3021.
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The inner hair cells (IHC’s) and outer hair cells (OHC’s) in the cochlea are vital components in the process of hearing. The IHC’s are responsible for converting sound-induced vibration into electrical signals. The OHC’s produce forces that amplify these vibrations and therefore enhance the electrical signals produced by the IHC’s. The resulting “cochlear amplifier” produces a nonlinear amplification which gives the ear its ability to detect sound pressure levels ranging from 20 μPa to 20 Pa (0 to 120 dB). This paper presents the modeling and testing of an artificial hair cell (AHC) piezoelectric sensor inspired by the hair cells found in the mammalian ear. The sensor is a bimorph cantilever beam consisting of a sensing piezoceramic element and an actuating piezoceramic element bonded to a brass substrate. The sensing element is used to detect the mechanical motion of the beam. Output feedback control can be used to send a voltage signal to the actuating element and alter the frequency response of the beam. A control law, which modifies the linear damping term of the first mode and introduces cubic damping, is used to create a closed-loop system perched at a Hopf bifurcation. The result is a system that produces a nonlinear amplification of the beam’s mechanical response in a manner which mimics the nonlinear behavior of the mammalian cochlea. This active sensor is studied under base acceleration and the initial test results are compared to a finite element model. Simulations of the closed-loop system are examined for the system with a single mode and for the system with multiple modes.
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della Rossa, Fabio, Massimiliano Gobbi, Giampiero Mastinu, and Giorgio Previati. "Countersteering to Recover Straight Ahead Running After a Disturbance." In ASME 2016 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/detc2016-60001.
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The paper deals with the analysis of a manoeuvre occurring frequently before crashes. Due to an external disturbance the straight ahead running of a vehicle is degradated into an oscillating motion. The driver is required to countersteer to recover the straight ahead motion. The bifurcation analysis of a simple model describing a vehicle+driver running straight ahead is performed. The mechanical model of the car has two degrees of freedom and the related equations of motion contain the non linear tyre characteristics. The driver is described by a non linear model defined by three parameters, namely the gain (steering wheel angle per lateral deviation from desired path), the prevision distance, the reaction time delay. Unreferenced bifurcations are discovered for the understeering vehicle. A supercritical Hopf bifurcation may occur as forward speed is increased. Also tangent (fold) bifurcations occur as the speed (or disturbance) are further increased. The vehicle+driver model is validated by means of a number of tests performed in a track. The validation relies on the identification of driver’s parameters. The track is equipped with a plank sliding laterally when the vehicle rear axle passes on it. Such a lateral excitation applies a disturbance to the vehicle which initiates a spin to be counteracted by the driver. An analysis is performed on driver’s parameters identification. Such parameter identification seems a possible way to assess single driver’s ability to perform recovery manoeuvres.