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2019 ◽  
Vol 323 (2) ◽  
pp. 136-148
Author(s):  
B.S. Tuniyev ◽  
T.V. Petrova

A new species of rock lizards of the genus Darevskia Arribas, 1997 – Darevskia aghasyani sp. nov. is described from Urts Ridge in Southern Armenia. This species is characterized by a combination of the following characters: small size L – 49–54 mm, L. cd – 107, Sq – 52–56, Ventr – 26–27, G – 24, P. g. – 32–34, P. fm. – 18–20; it is painted in brownish-beige tones from above; the belly is whitish in both sexes, males in the anal area have yellow with ochre femoral pores; bluish spots appear on the edge of the outer ventral shields at the middle of trunk through one shield; on the sides of the trunk (chest area) there are two blue spots in males and one in females; rostral is separated from frontonasal by nasal shields and it does not touch the nostril; upper postocular is twice wider than upper temporal shield; posterior temporal shields are not pronounced, or slightly pronounced; in front of central temporal (Massetericum), there is one enlarged temporal shield; along the throat from ear to ear fold there are 32-34 scales; two large preanal shields present in front of the anal shield. A comparison of Darevskia aghasyani sp. nov. with other species of the genus from Armenia and representatives of “raddei” complex from neighboring regions of Turkey and Iran (Darevskia dahli (Darevsky, 1957), D. unisexualis (Darevsky, 1966), D. raddei (Boettger, 1892), D. raddei vanensis (Eiselt et al., 1993), D. nairensis (Darevsky, 1967), and D. defilippii (Camerano, 1877)) is given. Conservation status of taxa assessed as CR B2ac(iv) "CRITICALLY ENDANGERED".


2019 ◽  
Vol 51 (4) ◽  
pp. 409-419 ◽  
Author(s):  
Marko Pavlovic ◽  
Marina Dojcinovic ◽  
Radica Prokic-Cvetkovic ◽  
Ljubisa Andric

The paper analyzes the morphology of cavitation damage of raw and sintered basalt samples. The experiment was conducted using the ultrasonic vibratory cavitation test method according to the ASTM G-32 standard. During the determination of the resistance to the effect of cavitation, a change in the mass of samples was observed in the function of the cavitation time of operation. The morphology of damage caused by the effect of cavitation was followed by scanning with an electron microscope, and the level of degradation of the surface of the samples was quantified using the image analysis. The results showed a significantly higher degree of resistance of sintered basalt, with a cavitation rate of 0.019 mg/min relative to raw basalt, with a cavitation rate of 0.738 mg/min. After 120 minutes of exposure to the cavitation effect, a smaller number of small pits on the surface of sintered basalt were observed, while a higher level of damage to the surface with the appearance of numerous pits was found in raw basalt, which can be connected in some places to larger and deeper pits in some places. The obtained results indicate the possibility of using sintered basalt for the production of parts that will be exposed to the effects of high cavitation loads.


2016 ◽  
Vol 256 ◽  
pp. 51-57 ◽  
Author(s):  
Annalisa Pola ◽  
Lorenzo Montesano ◽  
Ciro Sinagra ◽  
Marcello Gelfi ◽  
Marina La Vecchia

In this paper the effect of globular microstructure on the cavitation erosion resistance was assessed and compared to that of conventional dendritic one. Three different wrought aluminum alloys in as-cast conditions were investigated. The samples were completely characterized by metallographic analyses and microhardness measurements. Cavitation erosion tests were performed according to ASTM G 32 standard. The volume loss was evaluated during the test by periodical interruptions. It was identified the damaging mechanism in case of both dendritic and semisolid microstructure. It was also found that the globular microstructure increases the cavitation erosion resistance only for one of the studied alloys.


2016 ◽  
Vol 68 (2) ◽  
pp. 361-368 ◽  
Author(s):  
N.V. Sollecito ◽  
V.J. Andrade ◽  
F.A. Barbosa ◽  
C.F. Lobo ◽  
H.O. Azevedo ◽  
...  

Foram avaliadas as taxas de reconcepção de 98 novilhas primíparas (34 Guzerá - G, 32, 1/2 Guzerá x 1/2 Nelore - GN e 32,1/2 Red Angus x 1/2 Nelore - AN) com 14 meses de idade e peso médio de aproximadamente 249,65kg, criadas em pastos de Brachiaria brizantha cv Marandu. Na segunda estação de monta (EM), foram utilizadas apenas as 36 primíparas gestantes na primeira EM (três G, nove GN e 24 AN), com média de idade de 26 meses e peso corporal de 313,67±25,01kg, 336,50±45,84kg e 399,86±44,45kg, respectivamente, para as fêmeas dos grupos G, GN e AN. O grupo AN apresentou ganho médio diário (GMD) de 0,30±0,06 (kg/dia) e maiores taxas (58,33) de reconcepção (P<0,05), comprovando que a heterose resultante do cruzamento entre raças distintas com maior distância genética (Bos taurus taurus x Bos taurus indicus) proporciona maior desempenho produtivo e reprodutivo.


2011 ◽  
Vol 492 ◽  
pp. 75-79
Author(s):  
Jie Sheng Han ◽  
Yuan Ping Chen ◽  
Zhen Li ◽  
Zu Jun Chen ◽  
Jin Jun Lu
Keyword(s):  
G 32 ◽  

To evaluate the erosion of various engineering materials subject to cavitation in laboratory, a ultrasonic vibratory apparatus (UVA-1) is designed and manufactured according to ASTM G 32-06. The principle and setup of the UVA-1 are briefed. Some utilities of this apparatus are listed with several good examples.


2011 ◽  
Vol 436 (1) ◽  
pp. 16-19 ◽  
Author(s):  
V. B. Salenko ◽  
A. P. Kotnova ◽  
I. A. Glukhov ◽  
Yu. E. Stefanov ◽  
S. A. Surkov ◽  
...  

2010 ◽  
Vol 15 (2) ◽  
pp. 121-129 ◽  
Author(s):  
Hélio Ormeu Ribeiro ◽  
Augusto José de Almeida Buschinelli ◽  
Jair Carlos Dutra ◽  
Ana Sofia Clímaco Monteiro D´Oliveira
Keyword(s):  

A erosão por cavitação deteriora componentes em serviço, tais como partes metálicas de bombas de água, válvulas e, em especial, pás de turbinas hidráulicas, sendo nesse último caso responsável por elevados prejuízos ligados tanto aos custos da manutenção direta, como sobretudo às perdas por interrupção na geração de energia elétrica. Dentre os materiais aplicados no reparo por soldagem de danos por cavitação incluem-se aços inoxidáveis tradicionais tipo AISI 308 e 309, aços inoxidáveis ao Co e ligas à base de Co (stellites), caracterizando-se essas últimas pela maior sensibilidade a trincas, dificuldade de esmerilhamento e pelo mais alto custo. Nesse contexto este trabalho buscou formular, depositar e analisar o desempenho de aços inoxidáveis austeníticos CrMnSiN, soldados pelo processo PTA. A resistência à erosão por cavitação foi avaliada segundo a norma ASTM G 32-92. A microestrutura foi caracterizada por microscopia ótica e microscopia eletrônica de varredura e a formação de martensitas α' e ε, induzida pela cavitação, foi avaliada por difração de raios-X. A integridade da superfície dos depósitos foi controlada por END, além disso a dureza e a facilidade de acabamaneto por esmerilhamento serviram como critérios para avaliar os revestimentos soldados. Verificou-se que os revestimentos aplicados por PTA eram livres de trincas de solidificação, com baixa porosidade, boa molhabilidade e adequado acabamento superficial. A melhor liga inoxidável austenítica elaborada (0,03%C; 0,35% N; 13,2%Cr; 11,8% Mn; 2,8%Si; bal %Fe) mostrou uma resistência à erosão por cavitação próxima aquela das principais ligas comerciais.


2010 ◽  
Vol 5 (4) ◽  
pp. 146-151 ◽  
Author(s):  
R.N.R. Anreddy ◽  
N.R. Yellu ◽  
R.K. Devarakond ◽  
H. Vurimindi

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