Добірка наукової літератури з теми "Shell hardness"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся зі списками актуальних статей, книг, дисертацій, тез та інших наукових джерел на тему "Shell hardness".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Статті в журналах з теми "Shell hardness"
1
Freire Andrade, Ariana, and Rodrigo Bíscaro Nogueira. "Caracterización mecánica de conchas amazónicas de Pomacea dolioides (Reeve, 1856)." ACTA ZOOLÓGICA MEXICANA (N.S.) 34, no. 1 (October 29, 2018): 1–11. http://dx.doi.org/10.21829/azm.2018.3412120.
Повний текст джерелаАнотація:
We investigated the mechanical behavior of freshwater mollusk shells, Pomacea dolioides, collected from a floodplain area located in Amazonas, Brazil. With the purpose of characterizing the mechanical properties of the shells, bending, hardness and roughness tests were carried out. To determine the shell flexural strength, a new methodology was proposed for the calculation of it, considering the curved geometry of the specimens taken from the shells. It was also described the mechanical properties as a function of shell position and thickness, variation of the surface hardness along the shell and the low level of superficial irregularity in the inner layer of the shells. Shell presented a mean flexural rupture modulus (MOR) of 128.0 MPa, Rockwell HR15N hardness = 50 ± 8.3 and a low level of irregularities in the inner layer, roughness Ra = 0.160 μm.
2
Ikechukwu, I. F., O. S. Onwuka, and M. C. Nwogu. "Production of Periwinkle Shell Reinforced Grindstone." Journal of Applied Sciences and Environmental Management 26, no. 6 (June 30, 2022): 1157–62. http://dx.doi.org/10.4314/jasem.v26i6.24.
Повний текст джерелаАнотація:
The study involves the use of periwinkle shell particles as reinforcement in the production of grindstone to meliorate its physical and mechanical properties. The assessment of the properties of the periwinkle shell reinforced concrete grindstone showed that reinforcement yielded several promising results. The compressive strength was higher for samples with lower water/cement ratio (7%) than those with higher water/cement ratio (10%). The introduction of concrete that contains periwinkle shells as fine aggregates resulted in the loss of smooth like appearance and reduction in weight. The loss of its smooth like nature introduces the rough nature which improved its functionality. The reinforced sample had the lowest hardness test and in hardness test the lower the number the higher the hardness. There was an increase in the density after absorption test was carried out on specimens. There was also reduction in production cost with periwinkle shells partial replacement of cement and gravel as fine aggregate. The composite was adequate for grindstone production since its sample has a compressive of 18.15Mpa and thus satisfied MOR requirements of 11.5 MPa for general purpose boards.
3
Ji, Hong Mei, Yun Jiang, Wen Yang, Guang Ping Zhang, and Xiao Wu Li. "Comparisons of Microstructures and Hardness Distribution between Clinocardium Californiense and Veined Rapa Whelk Shells." Key Engineering Materials 544 (March 2013): 295–98. http://dx.doi.org/10.4028/www.scientific.net/kem.544.295.
Повний текст джерелаАнотація:
Abstract. Microstructures, phase compositions and microhardness distribution of two kinds of natural biological materials called Burnt-end Ark and Veined rapa whelk shells were studied and discussed for comparisons. It was found that the both shells present a hierarchical structure comprising three layers in thickness, i.e., inner, middle and outer layers. The inner and middle layers of the two kinds of shells exhibit cross-lamellar structures with somewhat of differences in the morphology and dimension. The outer layer presents a porous blocky structure for Burnt-end Ark shell and a layered structure for Veined rapa whelk shell. The X-ray diffraction (XRD) analyses show that all the layers of Burnt-end Ark shell as well as the inner and middle layers of Veined rapa whelk consist of crystalline aragonite CaCO3, while the out layer of Veined rapa whelk consists of crystalline calcite CaCO3. The microhardness measurements on the cross sections perpendicular to the growth lines of the shells demonstrate that the hardness of the both shells decreases gradually from the inner layer to the outer layer, strongly depending upon their microstructures.
4
DANYLUK, MICHELLE D., MARIA T. BRANDL, and LINDA J. HARRIS. "Migration of Salmonella Enteritidis Phage Type 30 through Almond Hulls and Shells." Journal of Food Protection 71, no. 2 (February 1, 2008): 397–401. http://dx.doi.org/10.4315/0362-028x-71.2.397.
Повний текст джерелаАнотація:
The ability of Salmonella to migrate from an external aqueous environment through the almond hull and shell, and to colonize the kernel, was evaluated in two ways. First, the outer surface of shell halves from five varieties of almonds that differed in shell hardness were placed in contact with a suspension of Salmonella enterica serovar Enteritidis phage type 30 for 24hat24°C. Salmonella Enteritidis was isolated from the inside of these almond shells in 46 and 100% of the samples, by direct swabbing of the inner surface of the shell and by enrichment from the swab, respectively. These findings suggested that hardness of the shell is not a significant factor in the migration of the pathogen through that tissue. In addition, both motile and nonmotile strains of S. enterica serovar Typhimurium migrated through the almond shells to the same extent under the conditions of this assay, indicating that bacterial migration through the wet shell may be a passive process. Second, whole almonds (intact hull, shell, and kernel) were soaked for 24 to 72 h at 24°C in a suspension of Salmonella Enteritidis phage type 30 labeled with the green fluorescent protein. Green fluorescent protein–labeled Salmonella cells were observed on the outer and inner surfaces of both the almond hull and shell, and on the kernel, by confocal laser scanning microscopy. Our data provide direct evidence that wet conditions allow for Salmonella migration through the hull and shell and onto the almond kernel, thus providing a means by which almond kernels may become contaminated in the field.
5
Handoko, Dwi, Vivaldi Vivaldi, and Sutrisno Sutrisno. "Pengaruh Variasi Jenis Katalisator Dan Holding Time Pada Proses Pack Carburizing Terhadap Perubahan Komposisi Karbon Dan Nilai Kekerasan Baja Karbon Rendah (Low Carbon Steel) St 37." Jurnal Vokasi 16, no. 1 (June 30, 2021): 38–45. http://dx.doi.org/10.31573/vokasi.v16i1.316.
Повний текст джерелаАнотація:
In this study, a pack carburizing process was carried out on low carbon steel using activated carbon, coconut shell charcoal and various catalysts in the form of ale-ale shells, eggshells, and beef bones. The method used is heating at an austenite temperature of 900 oC with a variation of holding time of 30, 60, and 90 minutes, then quenching using water, followed by hardness testing with the Vickers method and composition testing. The general result is that the three types of catalysts can accelerate the diffusion-reaction so that the carbon addition process occurs and the longer holding time can provide an opportunity for the carbon formed to transform from the pearlite microstructure to the austenite microstructure, and when quenching it forms the Martensite microstructure. Of the three types of catalysts that produced the highest hardness was an ale-ale shell, from the initial hardness 119 HV to 464 HV.
6
Li, Rui, Yue Pan, Di Chen, Xiangyu Xu, Guangrong Yan, and Tianyuan Fan. "Design, Preparation and In Vitro Evaluation of Core–Shell Fused Deposition Modelling 3D-Printed Verapamil Hydrochloride Pulsatile Tablets." Pharmaceutics 14, no. 2 (February 17, 2022): 437. http://dx.doi.org/10.3390/pharmaceutics14020437.
Повний текст джерелаАнотація:
The aim of the study was to investigate core–shell pulsatile tablets by combining the advantages of FDM 3D printing and traditional pharmaceutical technology, which are suitable for a patient’s individual medication and chronopathology. The tablets were designed and prepared with the commercial verapamil hydrochloride tablets as core inside and the fused deposition modelling (FDM) 3D-printed shell outside. Filaments composed of hydroxypropylmethyl cellulose (HPMC) and polyethylenglycol (PEG) 400 were prepared by hot melt extrusion (HME) and used for fabrication of the shell. Seven types of printed shells were designed for the tablets by adjusting the filament composition, geometric structure and thickness of the shell. A series of evaluations were then performed on the 3D-printed core–shell tablets, including the morphology, weight, hardness, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray powder diffraction (XRD), in vitro drug release and CT imaging. The results showed that the tablets prepared by FDM 3D printing appeared intact without any defects. All the excipients of the tablet shells were thermally stable during the extruding and printing process. The weight, hardness and in vitro drug release of the tablets were affected by the filament composition, geometric structure and thickness of the shell. The pulsatile tablets achieved personalized lag time ranging from 4 h to 8 h in the drug release test in phosphate-buffered solution (pH 6.8). Therefore, the 3D-printed core–shell pulsatile tablets in this study presented good potential in personalized administration, thereby improving the therapeutic effects of the drug for circadian rhythm disease.
7
Skripalenko, Mikhail M., Stanislav O. Rogachev, Boris A. Romantsev, Viacheslav E. Bazhenov, Mikhail N. Skripalenko, and Andrei V. Danilin. "Microstructure and Hardness of Hollow Tube Shells at Piercing in Two-High Screw Rolling Mill with Different Plugs." Materials 15, no. 6 (March 11, 2022): 2093. http://dx.doi.org/10.3390/ma15062093.
Повний текст джерелаАнотація:
AA6060 ingots were pierced in a two-high screw rolling mill (MISIS-130D) with guiding shoes (Mannesmann mill type). Three different plugs, i.e., a conventional entire plug, a plug with a cavity, and a hollow plug, were used for piercing. We established that the grain size decreases after piercing, by order of magnitude, compared to the initial non-pierced annealed bill, with a grain size of 100–400 μm, and the hollow shell grains are elongated along the piercing direction. The produced hollow shells had 30% higher hardness than the initial billet. The highest hardness values were obtained after piercing the conventional entire plug. The most uniform hardness distribution through the hollow shell’s volume was obtained after piercing the hollow plug. The cross and longitudinal section hardness measurements demonstrate that the hardness decreases from the outer surface to the inner surface of the hollow shells.
8
Meng, Yuan, Zhenbin Guo, Susan C. Fitzer, Abhishek Upadhyay, Vera B. S. Chan, Chaoyi Li, Maggie Cusack, Haimin Yao, Kelvin W. K. Yeung, and Vengatesen Thiyagarajan. "Ocean acidification reduces hardness and stiffness of the Portuguese oyster shell with impaired microstructure: a hierarchical analysis." Biogeosciences 15, no. 22 (November 16, 2018): 6833–46. http://dx.doi.org/10.5194/bg-15-6833-2018.
Повний текст джерелаАнотація:
Abstract. The rapidly intensifying process of ocean acidification (OA) due to anthropogenic CO2 is not only depleting carbonate ions necessary for calcification but also causing acidosis and disrupting internal pH homeostasis in several marine organisms. These negative consequences of OA on marine calcifiers, i.e. oyster species, have been very well documented in recent studies; however, the consequences of reduced or impaired calcification on the end-product, shells or skeletons, still remain one of the major research gaps. Shells produced by marine organisms under OA are expected to show signs of dissolution, disorganized microstructure and reduced mechanical properties. To bridge this knowledge gap and to test the above hypothesis, we investigated the effect of OA on juvenile shells of the commercially important oyster species, Magallana angulata, at ecologically and climatically relevant OA levels (using pH 8.1, 7.8, 7.5, 7.2). In lower pH conditions, a drop of shell hardness and stiffness was revealed by nanoindentation tests, while an evident porous internal microstructure was detected by scanning electron microscopy. Crystallographic orientation, on the other hand, showed no significant difference with decreasing pH using electron back-scattered diffraction (EBSD). These results indicate the porous internal microstructure may be the cause of the reduction in shell hardness and stiffness. The overall decrease of shell density observed from micro-computed tomography analysis indicates the porous internal microstructure may run through the shell, thus inevitably limiting the effectiveness of the shell's defensive function. This study shows the potential deterioration of oyster shells induced by OA, especially in their early life stage. This knowledge is critical to estimate the survival and production of edible oysters in the future ocean.
9
SHUAIB-BABATA, YUSUF LANRE, Ibrahim Owolabi Ambali, Lawal Babatunde Abdulqadir, Hassan Kobe Ibrahim, Ishaq Na’allah Aremu, and Taofeek Olawale Ibraheem. "Production of Abrasive Sandpaper using Periwinkle Shells and Crab Shells." International Journal of Engineering Materials and Manufacture 5, no. 2 (June 25, 2020): 55–61. http://dx.doi.org/10.26776/ijemm.05.02.2020.04.
Повний текст джерелаАнотація:
In this study, the abrasive properties of periwinkle shell and crab shell grains with the binding effect of polyester resin at high concentration were evaluated. The abrasive properties considered were the hardness, compressive strength and wear resistance. The shells were processed into grit standards by crushing, grinding and then sieving using ASTM E11 set of sieves into grain sizes of P40 and P60. Furthermore on, the grits were developed into polymer matrix composite with particles varying from 96 wt.% to 92 wt.% and resin 3 wt.% to 7 wt.% with 1 wt.% each of cobalt naphthalene and methyl ethyl ketone peroxide hardener respectively by mixing and mold compression using a hydraulic press. It was found that, with an increase in polyester resin content, the hardness and compressive strength increased, while the wear rate decreased. The composition with most improved abrasive properties was 92 wt.% periwinkle shell grains to 7 wt.% polyester resin.
10
Srikiran, S., Ch Venkatarao, and T. Raviteja. "Fabrication and Mechanical Properties of Hybrid Aluminum Metal Matrix Composite by Using Stir Casting Process." Advances in Science and Technology 106 (May 2021): 17–25. http://dx.doi.org/10.4028/www.scientific.net/ast.106.17.
Повний текст джерелаАнотація:
An attempt is made to study the influence of dispersion of Groundnut shell ash (GSA) on the hardness and density of Aluminum Metal Matrix Composite. It is an attempt to use agricultural waste in trying to enhance the mechanical properties of the already existing materials. The work deals with the use of groundnut shell ash, mixed with aluminum using stir casting process. . The composites with varying percentage of groundnut shell ash from 0% to 6% were prepared. The prepared specimens were tested before and after the heat treatment process in terms of its hardness using a Rockwell Hardness Tester. The present work attempts to compare the hardness and density of prepared composites as compared to the alloy. The comparison is carried out before and after the heat treatment process. The results indicate the increasing hardness value and reducing density of composites.
Дисертації з теми "Shell hardness"
1
Ferreira, Karen Carvalho. "Caracterização integral de frutos tamarindo (Tamarindus indica L.) do cerrado de Goiás, Brasil e aplicação em produtos drageados." Universidade Federal de Goiás, 2018. http://repositorio.bc.ufg.br/tede/handle/tede/9124.
Повний текст джерелаАнотація:
Submitted by Franciele Moreira (francielemoreyra@gmail.com) on 2018-12-04T14:19:57Z
No. of bitstreams: 2
Dissertação - Karen Carvalho Ferreira - 2018.pdf: 1790352 bytes, checksum: af26c1ceb016467d53f1e058cd107e58 (MD5)
license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5)Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2018-12-05T10:20:14Z (GMT) No. of bitstreams: 2 Dissertação - Karen Carvalho Ferreira - 2018.pdf: 1790352 bytes, checksum: af26c1ceb016467d53f1e058cd107e58 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5)
Made available in DSpace on 2018-12-05T10:20:14Z (GMT). No. of bitstreams: 2 Dissertação - Karen Carvalho Ferreira - 2018.pdf: 1790352 bytes, checksum: af26c1ceb016467d53f1e058cd107e58 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-03-09
Brazil is a country with different biomes and great diversity of little explored vegetal species, and the Cerrado biome is known for the wealth of resources and flora. Among the fruit trees in the Cerrado, the tamarind tree stands out. Its fruit has excellent nutritional properties, but researches involving all the fruit's uses are still insignificant. The objective of this work was to characterize and evaluate tamarind pulp, shell and seeds (Tamarindus indica L.), to develop salted dragees using the flours of the by-products shell and seeds, besides evaluating the nutritional and sensorial quality of the dragees produced. The fruits were collected in Rio Verde and Ceres, Goiás, Brazil, and divided into pulp, shell and seeds. Physical, chemical, nutritional, calorimetry and antioxidant and antinutritional analyzes were performed. The results of this study indicated that the collected fruits obtained a higher proportion of pulp in relation to the residual parts, presented high carbohydrate content and low water activity for the three portions (pulp, peels and seeds) and lower values of ash, lipids and proteins. The shell and seed flours presented high content of total dietary fiber and pulp of the fruit had acid pH and high titratable acidity. The seed flour had a water absorption and solubility index greater than the shell flour, and a lower oil absorption index. The tamarind pulp presented 4 peaks in its thermogram (from 35 to 155 °C), and the tamarind shell and seed flours presented pulp-like behavior after 115 °C with 2 endothermic peaks. All the analyzed fruit portions had high antioxidant capacity, not significantly different from each other. The methanolic extract was more efficient in the extraction of the phenolic compounds of the three portions of tamarind, being the highest content found in the seeds. The tamarind shell showed low toxicity to Artemia salina and the seeds and pulp presented no toxicity. For the antinutritional factors, the tamarind pulp showed the highest nitrate content and absence of trypsin inhibitor. The tamarind seeds presented the highest amount of tannins. For the elaboration of the salted dragee with application of flours of by-products of tamarind was used the design of mixture with six formulations of dragees, where the closest to the commercial in relation to hardness was selected for the sensory and proximal analyzes. The dragee selected had lower instrumental hardness than commercial dragee and low water activity, high lipid, protein and energy value. The addition of flours of tamarind by-products influenced the fiber content, which was higher than in the commercial dragee. The dragee selected was well accepted, with the exception of the appearance attribute and, according to the tasters, would probably buy the new product.
O Brasil é um país com diferentes biomas e grande diversidade de espécies vegetais pouco exploradas, e o bioma Cerrado é conhecido pela riqueza de fauna e flora. Dentre as frutíferas existentes no Cerrado, destaca-se o tamarindeiro. Seu fruto apresenta excelentes propriedades nutricionais, porém pesquisas envolvendo todas as utilidades do fruto ainda são pouco significativas. O objetivo do trabalho foi caracterizar e avaliar polpa, casca e sementes de tamarindo (Tamarindus indica L.), desenvolver drageados salgados utilizando as farinhas dos subprodutos cascas e sementes, além de avaliar a qualidade nutricional e sensorial dos drageados produzidos. Os frutos foram coletados em Rio Verde e Ceres, Goiás, Brasil, e divididos em polpa, cascas e sementes. Realizou-se caracterização física, química, nutricional, calorimetria, antioxidantes e antinutricionais. Os resultados desse estudo indicaram que os frutos coletados obtiveram maior proporção de polpa em relação as partes residuais, apresentaram alto teor de carboidrato e baixa atividade de água para as três porções (polpa, cascas e sementes) e menores valores de cinzas, lipídeos e proteínas. As farinhas de casca e semente apresentaram alto teor de fibra alimentar total e polpa do fruto apresentou pH ácido e alta acidez titulável. A farinha das sementes apresentou índice de absorção e solubilidade em água maiores que a farinha das cascas, e menor índice de absorção de óleo. A polpa de tamarindo apresentou 4 picos em seu termograma (de 35 a 155°C), e as farinhas de casca e semente de tamarindo apresentaram comportamento semelhante a polpa após 115 °C, com 2 picos endotérmicos. Todas as porções do fruto analisadas apresentaram capacidade antioxidante, não diferindo significativamente entre si. O extrato metanólico foi mais eficiente na extração dos compostos fenólicos das três porções do tamarindo, sendo o maior teor encontrado nas sementes. A casca apresentou baixa toxicidade frente a Artemia salina e as sementes e polpa não apresentaram toxicidade. Para os fatores antinutricionais, a polpa de tamarindo apresentou o maior teor de nitratos e ausência de inibidor de tripsina. As sementes de tamarindo apresentaram a maior quantidade de taninos. Para a elaboração dos drageado salgado com aplicação de farinhas de coprodutos de tamarindo foi utilizado delineamento de mistura com seis formulações de drageados, onde o mais próximo do comercial em relação à dureza foi selecionado para as análises sensorial e proximal. O drageado selecionado apresentou dureza instrumental inferior à do drageado comercial e baixa atividade de água, alto valor de lipídeos, proteínas e valor energético. A adição das farinhas de coprodutos de tamarindo influenciou o conteúdo de fibras, sendo este mais elevado que no drageado comercial. O drageado selecionado obteve boa aceitação, com exceção do atributo aparência e, de acordo com os provadores, provavelmente comprariam o novo produto.
2
Siwabessy, Paulus Justiananda Wisatadjaja. "An investigation of the relationship between seabed type and benthic and bentho-pelagic biota using acoustic techniques." Thesis, Curtin University, 2001. http://hdl.handle.net/20.500.11937/1678.
Повний текст джерелаАнотація:
A growing recognition of the need for effective marine environmental management as a result of the increasing exploitation of marine biological resources has highlighted the need for high speed ecological seabed mapping. The practice of mapping making extensive use of satellite remote sensing and airborne platforms is well established for terrestrial management. Marine biological resource mapping however is not readily available except in part from that derived for surface waters from satellite based ocean colour mapping. Perhaps the most fundamental reason is that of sampling difficulty, which involves broad areas of seabed coverage, irregularities of seabed surface and depth. Conventional grab sample techniques are widely accepted as a standard seabed mapping methodology that has been in use long before the advent of acoustic techniques and continue to be employed. However. they are both slow and labour intensive, factors which severely limit the spatial coverage available from practical grab sampling programs. While acoustic techniques have been used for some time in pelagic biomass assessment, only recently have acoustic techniques been applied to marine biological resource mapping of benthic communities. Two commercial bottom classifiers available in the market that use normal incidence echosounders are the RoxAnn and QTC View systems. Users and practitioners should be cautious however when using black box implementations of the two commercial systems without a proper quality control over raw acoustic data since some researchers in their studies have indicated problems with these two bottom classifiers such as, among others, a depth dependence. In this thesis, an alternative approach was adopted to the use of echosounder returns for bottom classification.The approach used in this study is similar to,~ used in the commercial RoxAnn system. In grouping bottom types however, Multivariate analysis (Principal Component Analysis and Cluster Analysis) was adopted instead of the allocation system normally used in the RoxAnn system, called RoxAnn squares. In addition, the adopted approach allowed for quality control over acoustic data before further analysis was undertaken. As a working hypothesis, it was assumed that on average 0 and aE2 = 0 where E1 and E2 are the roughness and hardness indices, respectively, and RO is the depth. For roughness index (E1), this was achieved by introducing a constant angular integration interval to the tail of the first OM returns whereas for hardness index (E2), this was achieved by introducing a constant depth integration interval. Since three different frequencies, i.e. 12, 38 and kHz, were operated, Principal Component Analysis was used here to reduce the dimensionality of roughness and hardness indices, formed from the three operated qu frequencies separately. The k-means technique was applied to the first principal component of roughness index and the first principal comp component of hardness index to produce separable seabed types. This produced four separable seabed types, namely soft-smooth, soft-rough, hard-smooth and hard-rough seabeds.Principal Component Analysis was also used to reduce the dimensionality of the area backscattering coefficient sA, a relative measure of biomass of benthic mobile biota. The bottom classification results reported here appear to be robust in that, where independent ground truthing was available, acoustic classification was generally congruent with ground truth results. When investigating the relationship between derived bottom type and acoustically assessed total biomass of benthic mobile biota, no trend linking the two parameters, however, appears. Nevertheless, using the hierarchical agglomerative technique applied to a set of variables containing average first principal component of the area backscattering coefficient sA, the average first principal component of roughness and hardness indices, the centroids of first principal component of roughness and hardness indices associated with the four seabed types and species composition of fish group of the common species in trawl stations available, two main groups of quasi acoustic population are observed in the North West Shelf (NWS) study area and three groups are observed in the South East Fisheries (SEF) study area. The two main groups of quasi acoustic population in the NWS study area and the three main groups of quasi acoustic population in the study area are associated with the derived seabed types and fish groups of the common species.
3
Siwabessy, Paulus Justiananda Wisatadjaja. "An investigation of the relationship between seabed type and benthic and bentho-pelagic biota using acoustic techniques." Curtin University of Technology, Department of Applied Physics, 2001. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=12197.
Повний текст джерелаАнотація:
A growing recognition of the need for effective marine environmental management as a result of the increasing exploitation of marine biological resources has highlighted the need for high speed ecological seabed mapping. The practice of mapping making extensive use of satellite remote sensing and airborne platforms is well established for terrestrial management. Marine biological resource mapping however is not readily available except in part from that derived for surface waters from satellite based ocean colour mapping. Perhaps the most fundamental reason is that of sampling difficulty, which involves broad areas of seabed coverage, irregularities of seabed surface and depth. Conventional grab sample techniques are widely accepted as a standard seabed mapping methodology that has been in use long before the advent of acoustic techniques and continue to be employed. However. they are both slow and labour intensive, factors which severely limit the spatial coverage available from practical grab sampling programs. While acoustic techniques have been used for some time in pelagic biomass assessment, only recently have acoustic techniques been applied to marine biological resource mapping of benthic communities. Two commercial bottom classifiers available in the market that use normal incidence echosounders are the RoxAnn and QTC View systems. Users and practitioners should be cautious however when using black box implementations of the two commercial systems without a proper quality control over raw acoustic data since some researchers in their studies have indicated problems with these two bottom classifiers such as, among others, a depth dependence. In this thesis, an alternative approach was adopted to the use of echosounder returns for bottom classification.The approach used in this study is similar to,~ used in the commercial RoxAnn system. In grouping bottom types however, Multivariate analysis (Principal Component Analysis and Cluster Analysis) was adopted instead of the allocation system normally used in the RoxAnn system, called RoxAnn squares. In addition, the adopted approach allowed for quality control over acoustic data before further analysis was undertaken. As a working hypothesis, it was assumed that on average 0 and aE2 = 0 where E1 and E2 are the roughness and hardness indices, respectively, and RO is the depth. For roughness index (E1), this was achieved by introducing a constant angular integration interval to the tail of the first OM returns whereas for hardness index (E2), this was achieved by introducing a constant depth integration interval. Since three different frequencies, i.e. 12, 38 and kHz, were operated, Principal Component Analysis was used here to reduce the dimensionality of roughness and hardness indices, formed from the three operated qu frequencies separately. The k-means technique was applied to the first principal component of roughness index and the first principal comp component of hardness index to produce separable seabed types. This produced four separable seabed types, namely soft-smooth, soft-rough, hard-smooth and hard-rough seabeds.
Principal Component Analysis was also used to reduce the dimensionality of the area backscattering coefficient sA, a relative measure of biomass of benthic mobile biota. The bottom classification results reported here appear to be robust in that, where independent ground truthing was available, acoustic classification was generally congruent with ground truth results. When investigating the relationship between derived bottom type and acoustically assessed total biomass of benthic mobile biota, no trend linking the two parameters, however, appears. Nevertheless, using the hierarchical agglomerative technique applied to a set of variables containing average first principal component of the area backscattering coefficient sA, the average first principal component of roughness and hardness indices, the centroids of first principal component of roughness and hardness indices associated with the four seabed types and species composition of fish group of the common species in trawl stations available, two main groups of quasi acoustic population are observed in the North West Shelf (NWS) study area and three groups are observed in the South East Fisheries (SEF) study area. The two main groups of quasi acoustic population in the NWS study area and the three main groups of quasi acoustic population in the study area are associated with the derived seabed types and fish groups of the common species.
4
Goonetilleke, Wasala Adikari Shashiprabha Nilupuli Sridevi Tennakoon. "Genetic analysis of reproductive and nut traits in almond [Prunus dulcis (Mill.) D.A. Webb]." Thesis, 2017. http://hdl.handle.net/2440/107579.
Повний текст джерелаАнотація:
Almond is a perennial tree crop with a gametophytic self-incompatibility (SI) system. The SI system of almond is controlled by a multi-allelic locus, S, which is about 70,000 bp long. A nearly complete sequence for the entire S locus sequence has been available only for the S₇ haplotype. In this research, next-generation sequencing technology was implemented to sequence the entire S locus simultaneously from 15 haplotypes. The results confirmed the accuracy of available S₇ haplotype sequence, generated the entire S locus sequences for the Sf [f subscript], S₁ and S₈ haplotypes and generated partial S locus sequences for 11 other haplotypes (S₃, S₅, S₆, S₉, S₁₃, S₁₄, S₁₉, S₂₂, S₂₃, S₂₅ and S₂₇). Comparisons among haplotype sequences revealed higher polymorphism in the region where the S-RNase and SFB genes are located and considerable differences in the number and locations of long terminal repeat retrotransposons. There are about 50 known S alleles, of which one confers self-fertility. For some of these, complete or partial S-RNase and SFB sequences are available. Here, more complete sequences were generated for several alleles of the S-RNase gene (S₃, S₆, S₉, S₁₃, S₁₉, S₂₂ and S₂₅) and the SFB gene (S₉, S₂₃ and S₂₇). In almond breeding, SI limits the parental combinations that can be used for crossing. Detection of S alleles prior to crossing would be beneficial. Until now, molecular detection of the S alleles has relied on detection of length polymorphisms in the S-RNase gene. Here, single nucleotide polymorphisms (SNPs) in the S-RNase and SFB genes were used in designing assays to distinguish among S alleles. This thesis also reports on the construction of linkage maps for Nonpareil and Lauranne based on genotyping-by-sequencing (GBS) and on the design of uniplex assays for detection of SNPs detected by GBS. These assays were applied to additional Nonpareil × Lauranne progeny and to progeny from three other Nonpareil crosses (Nonpareil × Constantί, Nonpareil × Tarraco and Nonpareil × Vairo). Data from all four populations were used to generate a composite map for Nonpareil. Comparisons of marker positions detected for Nonpareil and Lauranne with positions in the peach genome confirmed high collinearity between the almond and peach genomes. Quantitative trait loci analysis detected 23 genomic regions as affecting nut and/or kernel traits in Nonpareil × Lauranne. Nine and 14 QTLs were detected for Nonpareil and Lauranne, respectively. Of the kernel and nut traits mapped here, shell weight, kernel shape, tocopherol concentration, fatty acid concentration and oleic/linoleic ratio were mapped for the first time in almond. For shell hardness and oleic/linoleic ratio, markers were identified that could be useful for marker-assisted selection. Some of the QTLs related to fatty acid and tocopherol concentration were closely located to the genes that are known to be involved in the synthesis of fatty acids and/or tocopherols. Some of the sequence information generated here may be useful for designing primers to amplify these genes (or components of these genes) for resequencing from multiple almond genotypes.Thesis (Ph.D.) (Research by Publication) -- University of Adelaide, School of Agriculture, Food and Wine, 2017.
Книги з теми "Shell hardness"
1
Foyle, Timothy P. Field testing shell hardness gauges for the snow crab fishery. St. John's, Nfld: Dept. of Fisheries and Oceans, 1989.
Знайти повний текст джерела
2
Hicks, Dave. A handling study of dungeness crab at varying air exposure intervals and shell-hardness levels. Juneau, Alaska: Alaska Dept. of Fish and Game, Division of Commerical Fisheries, 1989.
Знайти повний текст джерелаЧастини книг з теми "Shell hardness"
1
Revankar, Dr Vanita D. "EVALUATION OF REMINERALISING POTENTIAL AND MICROHARDNESS OF THREE DIFFERENT MARINE SKELETAL SPECIES – CRASSOSTREA MADRASENSIS , PERNA VIRIDIS AND PENAEUS MONODON ON HUMAN TEETH ENAMEL — AN INVITRO STUDY." In Emerging Trends in Oral Health Sciences and Dentistry. Technoarete Publishers, 2022. http://dx.doi.org/10.36647/etohsd/2022.01.b1.ch023.
Повний текст джерелаАнотація:
On human dental enamel, the remineralisation efficiency of a subsurface enamel defect was evaluated using powder extracts from three marine skeletal species: Crassostrea madrasensis (oyster shell), Perna viridis (mussel shell), and Penaeus monodon (shrimp shell).Methods: The study included 60 freshly extracted human third molar teeth that were sectioned at the cement-enamel junction (CEJ). Later, each tooth coronal region was separated into two halves of enamel blocks, yielding 120 blocks that were exposed to the demineralization technique and categorised as follows: Subsurface demineralization + oyster shell powder extract form Group I. Group II: demineralization of the subsurface + mussel shell application Subsurface demineralization + shrimp shell powder extract (Group III). Group IV: subsurface demineralization plus clinpro application, followed by thirty days in artificial saliva. The intact enamel samples served as a positive control, whereas demineralized enamel samples served as a negative control. Using X-ray fluorescence spectroscopy, micro hardness testing, and energy dispersive x-ray spectroscopy,samples were evaluated for remineralisationThe samples were evaluated using X-ray fluorescence spectroscopy, energy dispersive x-ray spectroscopy and micro hardness testing for atomic analysis & surface microhardness. One-way ANOVA and the Tukey – Kramer multiple comparison tests were used for statistical analysis.
2
Yao, Wankai, Junbin Yan, Xiangcheng Li, Pingan Chen, and Boquan Zhu. "Enhancement Mechanical Properties of B4C Ceramics with the Core-Shell Structure Powders." In Advances in Transdisciplinary Engineering. IOS Press, 2022. http://dx.doi.org/10.3233/atde220433.
Повний текст джерелаАнотація:
In order to improve the mechanical properties of B4C ceramics, B4C@TiB2 composite powders with core-shell structure are prepared by molten salt method using B4C and Ti powders as raw materials. And B4C ceramics were prepared from B4C@TiB2 composite powders by spark plasma sintering (SPS). The results show that the B4C@TiB2 composite powders exhibit intact core-shell structure. The B4C@TiB2 composite powders improves the mass transfer during spark plasma sintering. When the molar ratio of B4C/Ti is 2/1, the relative density, Vickers hardness, fracture toughness and flexural strength of the BT1/2 sample are 94.2%, 26.9 GPa, 5.34 MPa·m1/2 and 570 MPa, respectively, which is best comprehensive properties.
3
Korma Erkano, Wolyu. "Impacts of Environmental Parameters on the Infectivity of Freshwater Snail." In Update on Malacology. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.99829.
Повний текст джерелаАнотація:
The successful transmission of the infective stage of the parasite (miracidia) depends on different factors. These free-living stages miracidia rely on their own stored energy and are directly exposed to environmental factors including disturbance resulting from pollution and human activities. There are different environmental factors that affect the cercarial infection of the snail. These include pH, temperature, salinity, dissolved oxygen, water hardness, habitat conditions, presence of predators and competitors, etc. Each of these factors may increase or decrease the freshwater snail’s infectivity. The more hydrogen ion concentration in the aquatic habitat could have an effect on the maturation and physiology of the parasitic stage (miracidia), leading to impaired survival and reduced infectivity. In contrast, high temperature increases snail infectivity. While low dissolved oxygen in the aquatic environment results in low snail infectivity. Regarding the presence of predators can result in low snail infectivity by consuming the schistosome egg and the snails themselves. Total hardness also had a negative impact on the prevalence of snail infection. The hardness of the water results in the shell hardening of snails subsequently leads to low infection of snail by miracidia.
4
P. V., Rajesh. "MOORA-Driven Decision Making to Select the Optimal Specimen of Organic CMCs." In Advances in Civil and Industrial Engineering, 48–73. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-7206-1.ch005.
Повний текст джерелаАнотація:
Bone grafting or bone implant is a typical procedure in surgery in which a missing or broken bone is replaced in order to treat bone fractures that pose a significant health risk to the patients. Several research works have been carried out in the past few years regarding various composite materials used in bone implants, their fabrication methods, and evaluation of their physical, mechanical, chemical, and thermal properties. The use of ceramic powders and ceramic-based composites in biomedical applications are steadily increasing over years mainly due to their advantages like high compressive strength, excellent hardness, etc. In this research work, organic ceramic matrix composites with varying proportions of conch shell and sea sponge are fabricated using powder metallurgy technique and their physicomechanical properties such as density, porosity, water absorption, and micro-hardness are evaluated. Finally, optimization of process parameters is done using multi-objective optimization based on ratio analysis (MOORA) to select the best possible specimen of CMCs.
5
Kaupp, Gerd. "Undue Hardness/Modulus Ratio Claims instead of Physical Penetration Resistance and Applications with Mollusk Shells: A Recent Study." In Basic Mathematics for Physically Correct Mechanical Properties from Indentations, 210–23. Book Publisher International (a part of SCIENCEDOMAIN International), 2022. http://dx.doi.org/10.9734/bpi/mono/978-93-5547-921-1/ch14.
Повний текст джерела
6
Fatima, Boukhlifi. "Sustainable Treatment of Heavy Metals by Adsorption on Raw Chitin/Chitosan." In Trace Metals in the Environment - New Approaches and Recent Advances. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.88998.
Повний текст джерелаАнотація:
The objective of this chapter was to treat metal pollution of wastewater rich in Pb2+, Cd2+, Cu2+, and Zn2+ ions by adsorption tests on the raw chitin/chitosan. Different origin namely shrimp (Ccre), crab (Ccra) and lobster (Clan). Raw shrimp chitin had a strong affinity for Pb2+ and Cd2+. The adsorption capacity of zinc on the crabs chitin is twice as great as that on the shrimp chitin. The kinetic study showed that more than 50% of these ions are adsorbed before equilibrium is reached (20 minutes). The adsorption kinetics also showed that the hardness of the shells has a negative effect on the kinetics of the adsorption process. Indeed, the adsorption of Pb2+ on the raw chitin shrimp requires only 30 minutes, while on the raw chitin lobster; the equilibrium time is 60 minutes. To ensure a sustainable treatment, sludge generated by adsorption of heavy metals was incinerated at high temperature. Incineration has led to calcite phases, which do not represent any toxicity on the environment and it can be recycled in the industry of solid materials (ceramics, cement, etc.). However, the regeneration of sludge by the acid changes the structure of the material and gives new adsorbent supports.
7
Fatima, Boukhlifi. "Sustainable Treatment of Heavy Metals by Adsorption on Raw Chitin/Chitosan." In Trace Metals in the Environment - New Approaches and Recent Advances. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.88998.
Повний текст джерелаАнотація:
The objective of this chapter was to treat metal pollution of wastewater rich in Pb2+, Cd2+, Cu2+, and Zn2+ ions by adsorption tests on the raw chitin/chitosan. Different origin namely shrimp (Ccre), crab (Ccra) and lobster (Clan). Raw shrimp chitin had a strong affinity for Pb2+ and Cd2+. The adsorption capacity of zinc on the crabs chitin is twice as great as that on the shrimp chitin. The kinetic study showed that more than 50% of these ions are adsorbed before equilibrium is reached (20 minutes). The adsorption kinetics also showed that the hardness of the shells has a negative effect on the kinetics of the adsorption process. Indeed, the adsorption of Pb2+ on the raw chitin shrimp requires only 30 minutes, while on the raw chitin lobster; the equilibrium time is 60 minutes. To ensure a sustainable treatment, sludge generated by adsorption of heavy metals was incinerated at high temperature. Incineration has led to calcite phases, which do not represent any toxicity on the environment and it can be recycled in the industry of solid materials (ceramics, cement, etc.). However, the regeneration of sludge by the acid changes the structure of the material and gives new adsorbent supports.
8
Ling, Roger, Paul Arthur, Georgia Clarke, Estelle Lazer, Lesley A. Ling, Peter Rush, and Andrew Waters. "Building Materials and Techniques." In The Insula of the Menander at Pompeii: Volume 1: The Structures. Oxford University Press, 1997. http://dx.doi.org/10.1093/oso/9780198134091.003.0011.
Повний текст джерелаАнотація:
Much of the ensuing discussion will focus on the working-out of structural sequences, first within individual houses or parts of houses, then within the insula as a whole. As a preface to this discussion, it is necessary to give a description of the building materials and techniques found in the insula. Brief surveys of Pompeian building techniques have appeared in various publications. Still one of the most serviceable accounts is that of R. C. Carrington in his article ‘Notes on the building materials of Pompeii” published in 1933, and most of the forms of construction found in I10 are discussed therein. First, the materials. The commonest is the socalled ‘Sarno stone’ (often inaccurately called limestone’), a yellowish white calcareous tufa which is very rough and porous, being riddled with the imprints of shells and vegetable matter; it is used both in large blocks to form quoins and the like and in smaller rubble for facing and infilling of all types. Next most common is a hard grey (trachytic) lava which is stronger and more water resistant than Sarno stone but which, because it is less easy to cut into regular shapes, is generally employed in the form of small rubble. An exception to this rule is its use for door thresholds, where its hardness is well suited to withstanding wear and tear. Rather less common in our insula is the red or purple vesicular lava known as cruma (English “scoria”), derived from the frothy upper crust of consolidated lava streams; it is occasionally cut into small blocks but more normally occurs as a sporadic material in rubble wall-facings where Sarno stone and grey lava predominate. The other main lithic materials found in the insula are varieties of tufo (tuff), formed by the consolidation of volcanic ashes. The brown or grey tuff from Nuceria (modern Nocera) is a hard and close-grained material containing darker brown or blackish specks. It can be easily cut to shape when freshly exposed in the quarry but hardens later on contact with the air, so is ideally suited for producing ashlar blocks, small tufelli (blocks of similar size to modern house bricks) and the pyramidal pieces used in reticulate work (opus reticulaium: see below), not to mention carved detail such as column and pilaster capitals.
Тези доповідей конференцій з теми "Shell hardness"
1
Sirun, Artian, Herotje Siwi, and Markus K. Umboh. "Effect of Density and Hardness on Burning Rate of Water Hyacinth and Coconut Shell Briquettes." In 2018 International Conference on Applied Science and Technology (iCAST). IEEE, 2018. http://dx.doi.org/10.1109/icast1.2018.8751547.
Повний текст джерела
2
Agus Imam, Dian Noviyanti, Ryana Budi Purnama, and Aris Aji Kurniawan. "The Effect of Addition of Blood Cockles (Anadara granosa) Shell Nano-Hydroxyapatite on Hardness of Heat Cured Acrylic Resin." In 1’s t Jenderal Soedirman International Medical Conference (JIMC) in conjunction with the Annual Scientific Meeting (Temilnas) Consortium of Biomedical Science Indonesia (KIBI ). SCITEPRESS - Science and Technology Publications, 2020. http://dx.doi.org/10.5220/0010490602370240.
Повний текст джерела
3
Ageorges, H., and P. Fauchais. "Splats and Coatings of Stainless Steel Particles Coated with an Alumina Shell." In ITSC 2000, edited by Christopher C. Berndt. ASM International, 2000. http://dx.doi.org/10.31399/asm.cp.itsc2000p0783.
Повний текст джерелаАнотація:
Abstract The effect of an alumina shell on stainless steel particles used in plasma spraying has been studied. The mean size of the injected particles is about 65 nm and the thickness of the alumina shell is 3 µm. The composite powder is plasma sprayed using a PTF4 type plasma gun with an internal injection 3 mm upstream of the nozzle exit. The results show that without preheating the substrate splats are extensively fingered and become circular when the substrate surface is preheated over 200°C. EDS analysis of the distribution of the various elements shows that the alumina either uniformly covers the stainless steel splat or is distributed in pieces over the surface. This behavior has been explained by collecting particles in flight and analyzing them. A composite stainless steel/alumina coating sprayed on a rough stainless steel substrate preheated to 400°C has been examined and compared with a pure stainless steel coating. Both hardness and cohesion are improved for the alumina coated particles due to the random distribution of alumina within the steel matrix.
4
Shao, Shanshan, Luowei Cao, Guodong Jia, and Zhiyuan Han. "Fitness for Service Assessment of a Propylene Heat Exchanger Subjected to Fire Damage." In ASME 2020 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/pvp2020-21342.
Повний текст джерелаАнотація:
Abstract Pressurized equipments maybe deform partially or wholly, and the mechanical properties of the construction material would be degraded due to a fire event. Fitness for service assessment can help to minimize reconstruction costs and allow safe resumption of unit operation as fast as possible. A propylene heat exchanger was exposed to overheating for about 3 hours due to a fire accident five or six meters far away. A fitness for service assessment was conducted according to API 579-1/ASME FFS-1. The material of the propylene heat exchanger is 09MnNiDR. The possible damage was examined by dimensional checks, hardness testing, in-situ field metallography, ultrasonic testing and magnetic particle testing. The heat exposure temperature of the propylene heat exchanger during the fire accident was estimated through the comparison between the results of in-situ field metallography examination and heat exposure simulation experiments. The heat exposure zones were identified based on the results of visual inspection and conjectural heat exposure temperature. The level 2 assessment was adopted to evaluate the heat exposure zones of V and VI. The approximate ultimate tensile strengths for the shell and the eastern head were converted from the hardness testing results. The caculated MAWP of the shell side is higher than the design pressure of the heat exchanger. The finite element method was adopted to evaluate the influence of the bulge in the upper part of the shell. The analytical results showed that the bulge had no significant effect on the operation of the heat exchanger before next inspection.
5
Cuenca-Alvarez, R., H. Ageorges, and P. Fauchais. "Stainless Steel Coatings Alumina Reinforced by Plasma Spraying Mechanofused Particles." In ITSC2003, edited by Basil R. Marple and Christian Moreau. ASM International, 2003. http://dx.doi.org/10.31399/asm.cp.itsc2003p0707.
Повний текст джерелаАнотація:
Abstract Stainless steel particles have been covered with an alumina shell by the mechanofusion process in order to reinforce stainless steel coatings by uniformly distributed alumina particles. Two stainless steel particle size distributions (PSD) in the range of 65 µm and 120 µm were tested. It was found that the mechanical energy input induced a spherical shape of the final composite particles with a controlled shell thickness (3 µm and 2 µm respectively) without forming new phases that usually take place during the mechanofusion process. The new spherically-shaped composite particles were sprayed in air with a D.C. plasma torch working with an Ar/H2 mixture as plasma forming gas. At mid-flight, two types of composite particles were detected : the first case corresponded to well molten particles where all the alumina shell has flowed to the tail of the particle ; the second case was related to particles which still retained some evidence of the alumina shell uniformly distributed around the stainless steel core. When the mechanofused particles were sprayed onto a cold smooth substrate (stainless steel 316L, Ra<0.05 µm), the resulting splats were extensively fingered and became disk shaped when the substrate surface was preheated over 300°C. However, alumina was either spread exactly on the stainless steel splat corresponding to well molten particles or dispersed in fingers and frozen over the surface of the stainless steel splat corresponding to particles covered by the broken alumina shell. An important effect of fine particle size on in-flight droplet behavior is detected because the center of gravity is more decentred than that of coarse particles influencing the deposit build-up. The composite stainless steel/alumina coatings sprayed on a rough stainless steel substrate (Ra = 6.7 ± 0.3 µm) preheated to 200 °C are compared to those of pure stainless steel. Hardness and adhesion/cohesion of deposits formed with fine particles were found to be improved comparatively to a pure stainless steel deposit. However, when coarse particles are used, the value of hardness is decreased and works is in progress to understand this phenomenon.
6
Nagarajan, Pratapkumar, and Donggang Yao. "Rubber-Assisted Hot Embossing for Structuring Thin Polymer Film Polymeric Films." In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-15297.
Повний текст джерелаАнотація:
Precision structured polymer thin films with microstructures comparable to or greater than the film thickness are highly desired in many applications. Such micro-patterned thin films, however, are difficult to fabricate using the standard hot embossing technology where both halves of the mold are made of hard materials. This study investigated a rubber-assisted embossing process for structuring thin polymer films. The advantages of the rubber backup instead of a hard support include but are not limited to 1) simplifying the embossing tool, 2) protecting the embossing master, 3) facilitating embossing pressure buildup, and 4) accommodating conformal forming of microscale shell patterns. Several design and process variables including rubber hardness, embossing temperature, embossing pressure and holding time were carefully studied. Thin polystyrene films in a thickness of 25 μm were accurately patterned with microgrooves of characteristic dimensions on the order of 100 μm.
7
Yamajo, Seiji, and Fumitaka Kikkawa. "PTFE Compound Bearing for Water Lubricated Shaft Systems." In SNAME 10th Propeller and Shafting Symposium. SNAME, 2003. http://dx.doi.org/10.5957/pss-2003-09.
Повний текст джерелаАнотація:
The paper outlines the development and applications of compound bearings made of PTFE (Poly Tetra Fluoro Ethylene) and synthetic rubber, which enable the shaft to start up without initial lubricating water. The unique characteristic is the three-layer structure using elastic, synthetic rubber which is sandwiched between the PTFE compound and the outer metal shell. This special structure is designed to solve bearing issues that are incompatible with each other. That the bearing has sufficient hardness to be excellent against wear and yet is flexible to compensate for shaft misalignment and vibration. Friction characteristics and performance data are introduced comparing PTFE and conventional rubber bearings. Long-time running tests are carried out in very demanding conditions and the test data are shown. Over 15 years of actual operational service data on naval vessels and high speed, long-distance cruising ferries are introduced.
8
Nakanishi, Tomoaki, Susumu Terada, Masato Yamada, Tadashi Ikeuchi, Ikuo Maeda, Tetsunao Ikeda, Ken Yamashita, Takeo Miyamura, and Shigenobu Nanba. "Development for Manufacture of Refining Reactors Made of 9Cr-1Mo-V Steel." In ASME 2017 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/pvp2017-65556.
Повний текст джерелаАнотація:
9Cr-1Mo-V steel, which was developed for application as a steam generator for fast breed reactors in the 1970s, has a higher strength at high temperatures and has been used for equipment and piping systems in the fossil power industries. ASME, Section VIII, Division 2 [1] gives 9Cr-1Mo-V steel a maximum design temperature of 649°C and an operating temperature of 500°C. And it has higher allowable stresses at 450°C or over, compared to 2¼Cr-1Mo-V steel. Therefore, if this material can be used, more economical pressure vessels operating at 454–500°C can be designed and manufactured. In our previous study for base metal, a large forged shell ring of 9Cr-1Mo-V steel was manufactured and for base metal welding, cracking susceptibilities and weldability were investigated. For overlay, welding consumables with high resistance to sigma phase embrittlement were developed [2]. In this study, highly efficient welding consumables for tandem SAW designed for circumferential welding of heavy wall shells were developed and welding using the full-scaled shell ring was demonstrated, and then the mechanical properties of the weld metal were evaluated. Results indicated that, regardless of the weld thickness, a minimum of 8 hours postweld heat treatment (PWHT) at 745°C was required to meet hardness and toughness requirements for conventional reactors. The strength of the materials can comply with the Code requirements after 3 cycles of PWHT considering the PWHT in fabrication and after weld repair. Furthermore, the following new Code Cases and Code revision were proposed and approved in order that pressure vessels can be designed in accordance with ASME, Section VIII, Division 2. • New Code Case for Fatigue Evaluation • New Code Case to apply SA-336-F91 in ASME Section VIII, Division 2 • Revision of Table 5A to add SA-336-F91 As a result, it has become possible to design and manufacture refining reactors to operate at 454–500°C.
9
Mitsuya, Masaki, Takashi Sakanoue, and Hiroyuki Motohashi. "Beam-Mode Buckling of Buried Pipeline Subjected to Seismic Ground Motion." In ASME 2012 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/pvp2012-78559.
Повний текст джерелаАнотація:
During seismic events, buried pipelines are subjected to deformation by seismic ground motion. In such cases, it is important to ensure the integrity of the pipeline. Both beam-mode and shell-mode buckling may occur in the event of compressive loading induced by seismic ground motion. In this study, the beam-mode buckling of a buried pipeline that occurred after the 2007 Niigataken Chuetsu-oki earthquake in Japan is investigated. A simple formula for estimating the critical strain, which is the strain at the peak load, is derived, and the formula is validated by finite-element analysis. In the formula, the critical strain increases with the pipeline diameter and hardness of the surrounding soil. By comparing the critical strain derived in this study for beam-mode buckling with the critical strain derived in a past study for shell-mode buckling, the formula facilitates the selection of the mode to be considered for evaluating the earthquake resistance of a pipeline. In addition to the critical strain, a method to estimate the deformation caused by seismic ground motion is proposed; the method can be used to evaluate the earthquake resistance of buried pipelines. This method uses finite-element analyses, and the soil–pipe interaction is considered. This method is used to reproduce the actual beam-mode buckling observed after the Niigataken Chuetsu-oki earthquake, and the earthquake resistance of a buried pipeline with general properties is evaluated as an example.
10
Prakash, Prakhar, Reid Concienne, Trevor Demayo, and Kirsten Towne. "Efficient Water Softening for Avoidance of Scales in Heavy Oil Steam Floods." In SPE Annual Technical Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/206115-ms.
Повний текст джерелаАнотація:
Abstract Pigging of Once Through Steam Generators (OTSGs) indicated various types of scales, the most predominant of these being silicates of hardness causing ions. It was noted that scaling propensity can potentially go up with higher Steam Quality (SQ) as the reject stream gets concentrated with ions. However, models suggested that there are benefits of higher SQ in enhancing fuel savings (8%) and electricity savings (2%) when SQ was increased by 20%. The challenges of higher SQ were noted in terms of increased scaling tendency and therefore the need for improved softening. In Field D, the service cycle, the backwash cycle, and the brining cycle were optimized leading to a gain in throughput and reduction in salt consumption. Service cycle improvement gained 30 % to 130 % in throughput between two regenerations, backwash cycle improvement by fluidizing the bed to nearly 35% helped gain 10% in throughput, and reduction of brining cycle from 75 minutes to 48 minutes helped reduce salt consumption by 56% without impacting the throughput. In Field B, a six month pilot revealed that shallow shell resins where ion-exchange is more efficient due to inert core (better intra particle diffusion control) can enhance the throughput by 30% - 80% and simultaneously reduce the number of regenerations by 15 – 30%. Resin fouling is still a major challenge to contend with as oil can foul the resin and throughput can decline by 0.5 – 3 folds. In a plant operation, where there are multiple softener and brine vessels, there is a need to optimize them as a system. Reliability, Availability, and Maintainability (RAM) Models are used in Field C to a) Address equipment configuration optimization with impact on capital capacity expansion project scope b) Understand how net softwater delivery capacity was affected by increases in inlet hardness and c) Assess through a comparison scenario, if the large cost of addressing the valve issue in an upstream nutshell filter was worth the lost production opportunity related to unplanned downtime.