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Artykuły w czasopismach na temat "Effect of Cemented Fill"
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Li, Chong Jian, i Wen Peng. "Effect of Collocation Ratio of Coarse and Fine WC on Dual Grain Structure Cemented Carbide". Advanced Materials Research 154-155 (październik 2010): 1040–52. http://dx.doi.org/10.4028/www.scientific.net/amr.154-155.1040.
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This paper adopts area conversion method to measure the WC grain size manually, sets up a Fibonacci Sequence plane segmentation model based on the statistical data obtained, and studies the effect of the ratio of coarse WC grains to fine WC grains on dual grain structure cemented carbide. It is believed that when SWC (fine) / SWC (coarse) ratio is 0.382, theoretically speaking, the arrangement between WC grains is the tightest. Through investigating the effect of WC grain boundary fusion on its stacking density and contiguity, and the effect of the dissolution and precipitation of WC grains on SWC(fine) / SWC(coarse) ratio, and combining Li Guangyu’s random stacking structure of the cemented carbide theory, it expounds the formation mechanism of the dual grain structure cemented carbide—making a proper amount of fine WC grains fill in the gaps between coarse WC grains so as to increase the stacking density and contiguity of WC grains to the maximum degree, and to separate the accumulated Co-phase layer between coarse WC grains, so that the Co layer more evenly distributes among the fine WC grains.
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Cao, Jing, Fangyi Liu, Siyang Huang, Hong Liu, Zhigang Song, Jianyun Li i Guoshou Liu. "Effect of UFC on the Microscopic Pore Structure of Cemented Soil in Humic Acid Environment". Sustainability 15, nr 4 (10.02.2023): 3241. http://dx.doi.org/10.3390/su15043241.
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Peat soil is widely distributed in the Dianchi Lake area of Yunnan, and the effect of the cement deep-mixing method on peat soil foundation is mainly affected by humic acid (HA). In this paper, a composite cement curing agent is formed by adding different proportions of ultra-fine cement (UFC) to ordinary Portland cement (OPC) and used to cure the HA-containing cohesive soil. Mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM), and X-ray powder diffraction (XRD) are used to study the influence mechanism of UFC on the micropore structure of HA-containing cemented soil. The unconfined compressive strength test (UCS) is used to verify it. MIP, SEM, and XRD results show that UFC can significantly improve the microscopic pore structure of the samples. The hydration reaction rate of cement increases with the increase in the proportion of UFC, and the generated hydration products can fill the pores of the samples. The filling effect of hydration products on macropores is enhanced, and the pores change from fibrous filling to cemented filling. The enhanced cementation of the hydration products improved the loose and overhead structure inside the sample. Enhancing the cementation of hydration products improves the loose and overhead structure inside the sample and the integrity of cemented soil. UCS verified that the increase in the UFC proportion increases the HA-containing cemented soil strength. It achieves the purpose of reducing the amount of cement when curing peat soil foundations and supports reducing carbon emissions in practical projects.
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Zhao, Kang, Qiang Li, Yajing Yan, Keping Zhou, Shuijie Gu i Shengtang Zhu. "Numerical Calculation Analysis of the Structural Stability of Cemented Fill under Different Cement-Sand Ratios and Concentration Conditions". Advances in Civil Engineering 2018 (27.08.2018): 1–9. http://dx.doi.org/10.1155/2018/1260787.
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The effect of lime-sand ratio and slurry concentration on the mechanical properties of backfills is important. To achieve green and high-efficiency mining, accurately determining the optimum ratio of cemented tailings for certain tungsten tailings and ensuring the safety and stability of the mine stope structure are important. The cement-sand ratios used in this research were 1 : 6 and 1 : 8. The mechanical properties were evaluated by using 68%, 72%, and 78% of tailing cemented filling materials. The corresponding physical and mechanical parameters were obtained through uniaxial compression, splitting, and shearing mechanical experiments on the backfill specimens. FLAC3D was used to investigate the mechanical properties of cement-filled pillars and the stability of supporting surrounding rocks on the basis of the mine’s current room pillar structure size parameters and mining sequence. The key factors that affect the stability of the goaf were analyzed by evaluating the plastic zone area of the stope, maximum and minimum principal stresses, and displacement change. The structural characteristics of stope structures and changes of rock mass damage were obtained under different cement-tailing ratios and concentrations. A cemented backfill with a cement-tailing ratio of 1 : 8 and a concentration of 68% was selected as the best solution for the mine in terms of safety and economic considerations.
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Liu, Naifei, Liang Cui i Yan Wang. "Analytical Assessment of Internal Stress in Cemented Paste Backfill". Advances in Materials Science and Engineering 2020 (22.12.2020): 1–13. http://dx.doi.org/10.1155/2020/6666548.
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To analytically describe the internal stress in a fill mass made of granular man-made material (cemented paste backfill, CPB), a new 3D effective stress model is developed. The developed model integrates Bishop effective stress principle, water retention relationship, and arching effect. All model parameters are determined from measurable experimental data. The uncertainties of the model parameters are examined by sensitivity analysis. A series of model application is conducted to investigate the effects of field conditions on the internal stress in CPB. The obtained results show that the proposed model is able to capture the influence of operation time, stope geometry, and rock/CPB interface properties on the effective stress in CPB. Hence, the developed model can be used as a useful tool for the optimal design of CPB structure.
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Béket Dalcé, Jean, Li Li i Pengyu Yang. "Experimental Study of Uniaxial Compressive Strength (UCS) Distribution of Hydraulic Backfill Associated with Segregation". Minerals 9, nr 3 (28.02.2019): 147. http://dx.doi.org/10.3390/min9030147.
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Stope backfilling with mine wastes has become a common practice in underground mines worldwide. Despite the increasing popularity in paste and rock fills, hydraulic fill made of classified mill tailings or sands remains commonly used in many mines. When such a slurried material is placed in a mine stope, a phenomenon known as segregation can take place associated with the quick drainage and consolidation of the hydraulic fill, thereby leading to a heterogeneous fill mass. While numerous publications have focused on the alleviation of segregation, there are few studies on the characterization of the distribution of geotechnical properties within hydraulic fill due to segregation. It is particularly scarce to quantify the spatial variation of the segregation and the resulting geotechnical properties after a backfill is placed in an opening. There is also a gap to quantitatively describe the degree of segregation using an appropriate expression or definition. The aim of this study is to investigate the effect of the segregation on the spatial variation of the geotechnical properties of hydraulic fill. Laboratory tests were performed with the cemented hydraulic backfill prepared with columns of different heights. The experimental results indicate that the segregation takes place and the resulting physical and mechanical properties can vary throughout the columns for samples higher than twice of the standard size. These results also indicate that the mechanical properties of a hydraulic fill obtained in a laboratory following the current practice with standard samples may not be representative of the fill mass placed in mine stopes. Expressions are proposed to quantify the degree of segregation associated with the spatial variation of particle sizes of mine hydraulic backfill.
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Moris, Izabela Cristina Maurício, Juliana Elias de Oliveira, Adriana Cláudia Lapria Faria, Ricardo Faria Ribeiro i Renata Cristina Silveira Rodrigues. "In Vitro Fit and Cementation Resistance of Provisional Crowns for Single Implant-Supported Restorations". Brazilian Dental Journal 26, nr 5 (październik 2015): 468–73. http://dx.doi.org/10.1590/0103-6440201300289.
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Abstract: This study aimed to verify marginal fit and the effect of cement film thickness standardization on retention of provisional crowns made with prefabricated acrylic cylinders on abutments, using two temporary luting agents subjected or not to mechanical cycling. Provisional crowns were made from bis-acryl (Luxatemp Fluorescence) or methyl methacrylate (Duralay) resins on acrylic cylinders and marginal fit and cement film thickness were evaluated. For retention evaluation, crowns were cemented with two temporary luting agents: non-eugenol zinc oxide (Tempbond NE) or calcium hydroxide-based (Hydcal) cements and subjected to tensile strength in a universal testing machine. After cleaning, debonded crowns were cemented again, subjected to mechanical cycling and retention was reassessed. The results of marginal fit and cement film thickness were analyzed by Student's t-test while retention of cements before and after mechanical cycling was analyzed using a mixed linear model. Methyl methacrylate crowns presented greater marginal misfit (p=0.001) and occlusal cement film thickness (p=0.003) than the bis-acryl ones. No difference was observed at axial cement film thickness (p=0.606). Resins (p=0.281) did not affect crown retention, but luting agents (p=0.029) and mechanical cycling (p=0.027) showed significant effects. The only significant interaction was mechanical cycling*luting agents, which means that luting agents were differently affected by mechanical cycling (p=0.002). In conclusion, the results showed that bis-acryl resin associated to calcium-hydroxide luting agent provided the best retention and lower cement thickness.
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Jia, Xiao Ming, Yue Xin Song i Suo Xia Hou. "Inhibition Effect of Compound Boricacidester on the Tungsten Carbide Leaching of the Cemented Carbide Tool". Advanced Materials Research 418-420 (grudzień 2011): 977–81. http://dx.doi.org/10.4028/www.scientific.net/amr.418-420.977.
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Working fluid is commonly used in the making and using progress of cemented carbide tool. The tungsten carbide leaching of cemented carbide tool will be resulted in by the sodium carbonate in cutting fluid, because of the tungsten carbide will occur oxidative dissolution. The inhibitor that suppress tungsten carbide leaching of cemented carbide tool is investigated by soaking experiments, friction experiments, SEM analysis, and energy spectrum analysis. The test result shows that aqueous solution and sodium carbonate will cause tungsten carbide leaching through oxidative dissolution; but compound boricacidester contain benzotriazole could suppress tungsten carbide leaching. The Inhibition mechanism is that compound boricacidester contain benzotriazole could generate complete and compact protective film on the surface of cemented carbide tool, therefore, tungsten carbide leaching is inhibited. Add compound boricacidester contain benzotriazole to the water-based cutting fluid could suppress tungsten carbide leaching effectively.
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Yuan, Jia Jing, Wen Zhuang Lu, Dun Wen Zuo i Feng Xu. "Contact Stress Analysis of NCD Coating on Cemented Carbide". Key Engineering Materials 431-432 (marzec 2010): 98–101. http://dx.doi.org/10.4028/www.scientific.net/kem.431-432.98.
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The contact stress of cemented carbide with NCD coating in elastic contact was analyzed using ANSYS. Factors such as elastic modulus and thickness of NCD film and elastic modulus of interlayer which affect the shear stress distribution of NCD film on cemented carbide substrate were investigated. The results show that the maximum shear stress point moves towards the interface with the increase of film elastic modulus. Film thickness has a significant effect on shear stress distribution of NCD film. High shear stress develops in the film layer with the increase of film thickness. Interlayer with low elastic modulus will cause shear stress concentration in NCD film.
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Jia, Xiao Ming, i Fei Wang. "Influence of Antirusting Aggent on the Cobalt Leaching of the Cemented Carbide Tool". Key Engineering Materials 407-408 (luty 2009): 317–20. http://dx.doi.org/10.4028/www.scientific.net/kem.407-408.317.
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The cutting fluid is widely used in cutting process with the cemented carbide tool. This paper studied the influence of some antirusting aggents, such as triethanolamine, tri-sodium phosphate, benzotriazole, sodium carbonate anhydrous, on the cobalt leaching of the cemented carbide tool by soaking test. The test results showed that a cobalt on cememted carbide surface and triethanolamine can produce complex compound into solution that made the cobalt leaching. The cobalt of the cemented carbide with the ion of the tri-Sodium phosphate in a water solution can form the loose deposition which leaded to the cobalt leaching.The benzotriazole and the cobalt can generate complex compound film covering on cemented carbide to effective inhibits the cobalt leaching. The inhibitive effect about the cobalt leaching of the sodium carbonate anhydrous is carried out through cathode reaction. The cobalt leaching of cemented carbide tool is effective inhibited by adding the benzotriazole and the carbonate anhydrous in the water-based cutting fluid.
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Gao, Bo, Shuai Cao i Erol Yilmaz. "Effect of Content and Length of Polypropylene Fibers on Strength and Microstructure of Cementitious Tailings-Waste Rock Fill". Minerals 13, nr 2 (18.01.2023): 142. http://dx.doi.org/10.3390/min13020142.
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The mechanical strength properties of cemented tailings backfill are very important for the safe and environmentally friendly mining of mineral resources. To check the impact of polypropylene fiber on strength and microstructure of cementitious tailings waste rock fill (CTWRF), diverse fiber lengths (6 and 12 mm) and dosages (0-control specimen, 0.3, 0.6, and 0.9 wt.%) were considered to prepare fiber-reinforced CTWRF (FRCTWRF) matrices. Experiments such as UCS (uniaxial compressive strength), X-ray CT (computed tomography), and SEM (scanning electron microscopy) were implemented to better characterize the backfills studied. Results showed that UCS performance of FRCTWRF was the highest (0.93 MPa) value at 6 mm fiber long and 0.6 wt.% fiber content. The peak strain of FRCTWRF was the highest (2.88%) at 12 mm fiber long and 0.3 wt.% fiber content. Growing the length of fiber within FRCTWRF can reduce its fracture volume, enhancing the crack resistance of FRCTWRF. Fiber and FRCTWRF are closely linked to each other by the products of cement hydration. The findings of this work will offer the efficient use of FRCTWRF in mining practice, presenting diverse perspectives for mine operators and owners, since this newly formed cementitious fill quickens the strengths required for stope backfilling.
Rozprawy doktorskie na temat "Effect of Cemented Fill"
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Jayasinghe, Mudiyanselage Harshani Dilanka Jayasinghe. "Scaled - Down Open Stoping Under Cemented Paste Fill". Thesis, Curtin University, 2020. http://hdl.handle.net/20.500.11937/79930.
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The principle scope of this research was to develop relationship between stope dimensions and cemented paste fill strength. Experiments in various fill thickness to span width ratios with cemented paste fill with different mechanical properties were conducted by using a constructed scaled-down open stope. Scaled-down laboratory experiments were used to understand the mechanism of fill failure when exposure is undertaken under a relatively fresh fill mass.
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Hughes, Paul B. "Design guidelines : underhand cut and fill cemented paste backfill sill beams". Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/47089.
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Difficult ground conditions negatively affect both mine production and the safety of underground workers. Underhand cut-and-fill mining is a potential solution to these issues. Discussions with mine sites revealed the use of sill beams in underhand cut-and-fill mining is not optimized. Optimization in ground support, development of in-situ strength test, and revisions of design standards are desired. Ultimately, the operations require the minimum cemented paste backfill (CPB) strength for a stable span.
Operational concerns were addressed by a multi-prong approach investigating stability of CPB sill beams using observational, experimental and analytical techniques. A case study approach summarizing the design of five mines utilizing underhand cut-and-fill with CPB is presented for different ground conditions. A historical study of span widths and beam strengths for the Stillwater mine is presented.
Laboratory testing determined the stress-strain behaviour of CPB. CPB follows a hyperbolic elastic loading path to peak stress followed by a strain-softening associated with the decay of the cohesion values. Additional testing found that cohesive and tensile strength values were on average 35 and 20 percent respectively of the unconfined compressive strength. This finding impacts sill beam design strengths as previous assumptions were conservative. Test database analyses from three mine sites found that sample size and location preparation has no effect on the strength of the sample. In-situ testing methods common in other industries were not practical with CPB; rather the in-situ strength can be represented by a site specific moisture content index relationship.
Review of current design methodology noted closure stresses were absent from the majority; a method was developed to assess closure for sill beam stability. The potential for critical failures were determined through a Monte Carlo probabilistic model. Methods reducing the risk of failure based on the simulation are investigated. Analysis found ground support does not improve the structural stability of the sill beam. Ground support keeps the beam intact: beam equations govern stability. The stability of sill beam in a seismic environment was analyzed based on the strain-energy density of the beam. The research concludes with a design guideline for CPB sill beams.
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Rask, Amanda. "Indirect methods as quality control of cemented hydraulic fill : Renström mine, Boliden mineral AB". Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-72962.
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The Renström mine, Boliden Mineral AB, uses, among other methods, the Transverse long hole stoping method with backfill. The mine uses a cement-stabilized hydraulic fill (CHF), which is a mixture of enrichment sand, cement and water. The most important factor in relation to strength is the water cement ratio. Today, only tests have been performed on the surface and in laboratory tests. The purpose of this work is thus to study the possibility of using other types of methods that can give a better understanding of the strength of the entire filling volume. Studies on backfill containing Portland cement and sulphur have shown that the UCS strength decreases with time, which can cause problems for the mine. A leaching method (MRM leaching test) used to evaluate potential sulphide soils has been used in this study on the backfill to investigate the sulphurs impact on the cement mixture. Electrical conductivity, pH, and redox potential were investigated and gave similar results, where the higher cement levels (8%, 10%, and 12%) were indistinguishable while the lower cement content (4%) differed significantly from the other levels. This probably indicates that the higher cement levels have a greater resistance to the influence of the sulphur. The most promising results were given when the method was used on enrichment sand alone. The linear lowering of the pH value of the enrichment sand, from pH 4.9 to about pH 3, point to that the enrichment sand contains large amounts of sulphur, as previously chemical analysis has shown. This suggests that the method can best be used in an early stage before the sand is mixed with cement. The strength results on the samples showed a strength after 7 days that was in line with the 90-day strength. However, all 90 day samples had decreased in strength during the time sequence, which may be an effect of the sulphur content, but should be further investigated to be determined. The smaller size of the samples was also experienced as a challenge during the temperature measurements due to small temperature variations and environmental effects. A maturity method for predicting the strength of concrete called "The maturity method" has been investigated in this study. To determine the strength maturity relationship, both the temperature related to time and the equivalent age must be evaluated. The study showed that the method cannot be used on the mine's backfill without first making adjustments related to the lower cement content used in the backfill compared with concrete constructions, since it is not possible to determine the strength growth in the early stage as the method requires.
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Berglund, Lina. "The Effect of Cooling Rate on Sintered Cemented Carbides". Thesis, KTH, Materialvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-288541.
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Magnetic measurements are useful tools for quality control of cemented carbides. Previous work at Sandvik Mining and Rock Technology has shown that the coercivity increases with increased cooling rate during sintering for a specific grade. This study aims to investigate why the coercivity changes with the cooling rate and if this is true for other cemented carbide grades as well. Three different cemented carbide grades were sintered with different cooling rates and evaluated with coercivity, Cobalt-magnetic saturation and hardness measurements, and with microscopy and Electron Backscatter Diffraction analysis. It was found that the coercivity increased with increasing cooling rates for the previously studied grade, but not for the two other grades. It was expected that the increased coercivity would indicate a decrease in WC grain size, but the results showed that the WC grain size of the fastest and slowest cooling rate were the same. However, a change in size of the Co areas between the WC grains was found. The fast cooled sample showed smaller Co areas than the slow cooled sample. These Co/WC grain boundaries increase the coercivity. An increased fraction of hcp-Co/fcc-Co was also found for the fast cooled material which also increases the coercivity. No relationship between the hardness and the coercivity or the cooling rate was found. The contiguity for the different grades was also calculated. No significant difference in contiguity between the different cooling rates of each material was found but the contiguity values between the different materials differed. This is probably mainly dependent on the different binder contents of the materials.Magnetiska egenskaper är en viktig del av kvalitetskontrollen av hårdmetaller. Tidigare forskning hos Sandvik Mining and Rock Technology har visat att koerciviteten hos en hårdmetallsort ökar med ökad kylhastighet vid sintring. Målet med den här studien är att undersöka varför koerciviteten ökar med kylhastigheten och om detta även gäller andra hårdmetallsorter. Tre olika hårdmetallsorter sintrades med olika kylhastigheter undersöktes med mätningar av koercivitet, magnetisk mättnat i koboltfasen och hårdhet, samt med mikroskopi och Electron Backscatter Diffraction analys. Det visade sig att koerciviteten ökade med ökad kylhastighet för hårdmetallsorten som studerats tidigare, men inte för de andra två sorterna. En ökad koercivitet förväntas visa på en minskad WC-kornstorlek, men resultaten visar att det långsamt kylda och snabbkylda provet hade samma WC-kornstorlek. Däremot upptäcktes en ändring av storleken på Co-områdena mellan WC-kornen. Det snabbkylda provet visade en mindre storlek av Co-områdena jämfört med det långsamt kylda provet. Fler Co/WC-korngränser i det snabbkylda provet leder till en ökad koercivitet. Fraktionen av hcp-Co/fcc-Co-korngränser ökade också för det snabbkylda provet vilket också ökar koerciviteten. Inget samband mellan hårdheten och koerciviteten eller kylhastigheten upptäcktes. Beräkning av kontiguiteten för de olika sorterna genomfördes också. Ingen signifikant skillnad i koercivitet mellan de olika kylhastigheterna för the olika sorterna hittades, men kontiguiteten mellan de olika sorterna varierade. Det beror mest troligt på att dom olika sorterna har olika mängd matrismaterial.
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Bertrand, Timothy Paul. "Effect of water maldistribution on cooling tower fill performance evaluation". Thesis, Stellenbosch : University of Stellenbosch, 2011. http://hdl.handle.net/10019.1/6841.
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Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2011.ENGLISH ABSTRACT: A 1.5 x 1.5 m2 counter-flow fill performance test facility is described in detail. Instrumentation was selected and installed in the cooling tower fill test facility and calibrated to ensure measurement accuracy. A facility control program was written to simplify the operation of the test facility via a user interface. The program calculates automatically the Merkel number and loss coefficients as measures of fill thermal and flow performance respectively. A spray frame was designed and manufactured to ensure uniform water distribution to the fill. The water distribution through different fills with varying fill heights and different water flow rates was measured. The water attached to the walls of the test facility was examined. Film, trickle and splash fills are tested in the upgraded test facility. The film and trickle fill performance determined during testing is deemed acceptable as these fills have minimal migration effects. Fills with poor distribution effects and large migration of water towards the walls of the test facility, like the splash fill tested, cannot to be tested accurately in a 1.5 x 1.5 m2 test section as the results do not represent the performance of the fill in a relatively large cooling tower. Other aspects examined were: • air flow uniformity • air fill bypass effects • location of water inlet and outlet temperature measurement points • location of pressure measurement probes. It was determined that, in the current test facility: • air uniformity is suitable for performance testing • air bypass effects can be ignored for open fills and can be minimised for dense fills by packing sponge between the fill and walls • water inlet and outlet temperatures should be measured in the pipe-work, resulting in a measurement method that is not influenced by the relative weightings of each thermocouple • pressure difference over the fill height measured by the pressure measurement tap is independent of its location on the fill outlet plane provided the pressure measurement points are perpendicular to the air stream and are not against the walls.
AFRIKAANSE OPSOMMING: 'n 1.5 x 1.5 m² Teenvloei pakking werkverrigting toetsfasiliteit word in detail beskryf. Instrumentasie is gekies en geïnstalleer in die koeltoring pakking toetsfasiliteit en gekalibreer om akkuraatheid te verseker. 'n Fasiliteit beheer program is geskryf om die gebruik van die toetsfasiliteit te vereenvoudig. Die program het ‘n vriendelike gebruikers intervalk. Die program bereken outomaties die Merkel-getal en verlies koëffisiënte as mate van pakking termiese- en vloeiwerksverrigting. 'n Sproeiraam is ontwerp en vervaardig om uniforme water verspreiding aan die pakking te verseker. Die water verspreiding deur verskillende pakkings met verskillende pakking hoogtes en water vloei snelhede is gemeet. Die water aangeheg aan die mure van die toetsfasiliteit is ook ondersoek. Film, druppel en spat pakkings word in die opgegradeerde toetsfasiliteit getoets. Die film- en druppelpakking werksverrigting bepaal tydens die toetse is aanvaarbaar, aangesien hierdie pakkings minimale migrasie effekte het. Pakking met swak verspreiding effekte en 'n groot migrasie van water na die wande van die toetsfasiliteit, soos gevind met die spatpakking toetse, kan nie met akkuraatheid in 'n 1.5 x 1.5 m² toets seksie getoets word nie omdat die resultate nie die werkverrigting van die pakking verteenwoordig in 'n relatief groot koeltoring. Ander aspekte wat ondersoek was: • lugvloei uniformiteit • lug omleiding effeckte • die posisie van water in- en uitlaat temperatuur meetpunte • posisie van die drukmeetapparaat. Dit is vasgestel dat, in die huidige toetsfasiliteit • lugvloei eenvormigheid geskik is vir prestasietoetsing • lug omleiding effekte kan geïgnoreer word vir oop pakkings en kan verklein word vir digte pakkings deur spons tussen die pakking en mure te pak • water inlaat- en uitlaattemperature behoort gemeet te word in die pypwerk en lei tot 'n metings metode wat nie beïnvloed word deur die relatiewe gewigte van elke thermokoppel nie • die druk verskil gemeet deur die drupmeetpunte oor die pakkinghoogte is onafhanklik van hul posisie op die pakkinguitlaatvlak op voorwaarde dat die drukmeetpunte loodreg is teen die lugstroom en nie teen die mure nie.
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Jacobs, Jessica. "Effect of post-treatment of cemented carbide : Microstructural investigation and evaluation of mechanical properties of cemented carbide inserts for rock tool applications". Thesis, Karlstads universitet, Avdelningen för maskin- och materialteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-84628.
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Cemented carbides are used in rock tool applications by reason of their beneficial mechanical properties, i.e. a combination of high toughness, wear resistance and hardness. The cemented carbides commonly receive their hardness from tungsten carbides (WC) whereas cobalt (Co) is the dominating binder material. To obtain a beneficial balance of these desired properties, the binder phase can be strengthened by post-sintering treatment to minimize the risk of catastrophic failure. Previous work has shown that the face centered cubic (FCC) cobalt phase is stabilized by a higher degree of dissolved tungsten in the binder. The residual stresses have been related to both further stabilization of the FCC and local transformation to a hexagonal close packed (HCP) phase. By exposing the inserts to mechanical deformation, i.e. inducing stress, the Co-binder material could theoretically transform from FCC to HCP. In this master thesis, five cemented carbides with three different binder phase compositions have been investigated. Additionally, the influence of the carbon content and addition of an alloying element was evaluated. This was done by electron backscatter diffraction (EBSD) analysis of the microstructure of each sample in as-sintered state and after post-treatment to gain better understanding on how the phase stability of the binder is affected by a post-sintering process. In addition, magnetic measurements, hardness-testing and mechanical tests were performed on the materials to evaluate the effect of using different binder compositions. It was found that a low carbon content provides smaller and more rounded WC grains and binder phase dominated by FCC-Co compared to an equivalent material with a high carbon content. A low carbon content furthermore resulted in a more wear resistant material. The addition of alloy MA presented a greater increase in surface hardness after post-treatment and made the materials even more wear resistant compared to the non-alloyed. The non-alloyed material performed better in a test measuring the fracture energy. A material with an Fe-based binder showed the least increase in surface hardness and the highest increase and overall fracture energy. All materials experienced a WC grain size refinement and an increase in their surface hardness after post-treatment. Only one material gave an indication on FCC to HCP phase transformation, no conclusions could be drawn from the other samples.Hårdmetaller används i bergborrstift på grund av materialets fördelaktiga mekaniska egenskaper vilket innefattar en kombination av hög seghet, hårdhet och bra nötningsmotstånd. Hårdheten uppnås vanligen av volfram karbider (WC) medan segheten ges av en bindefas som oftast är baserad på cobolt (Co). För att få ett material med en bra balans mellan seghet och hårdhet så kan bindefasen stärkas genom en ytbehandling efter sintringen för att minimera risken för att borrstiftet går sönder under användning. I tidigare studier har det framkommit att ytcentrerad kubiskt tätpackad (FCC) cobolt stabiliseras av volfram som lösts i bindefasen. Spänningar som uppkommer på grund av detta har relaterats till vidare stabilisering av FCC-fasen, men även lokal omvandling till hexagonalt tätpackad (HCP) cobolt. Genom att utsätta borrstiften för mekanisk deformation, i.e. inducera spänningar, kan bindematerialet teoretiskt sett omvandlas från FCC till HCP. I detta examensarbete har fem bergborrstift med tre olika bindefassammansättningar undersökts. Därutöver har även inverkan av kolhalten och tillägget av ett legeringsämne utvärderats. Den primära metoden för att genomföra undersöka mikrostrukturen hos de sintrade och efterbehandlade stiften var bakåtspridd elektrondiffraktion (EBSD). Syftet med undersökningen var att öka förståelsen kring bindefasens fasstabilitet då den utsatts för en efterbehandlingsprocess. Även magnetisk mätning, hårdhetstestning och mekanisk prövning utfördes på materialen för att kunna jämföra de olika bindefassammansättningarna mot varandra. Resultaten visade att en låg kolhalt gav ett material med mindre och mer rundade WC korn samt att bindefasen dominerades av FCC-Co jämfört mot ett material med samma bas och hög kolhalt. Därtill uppvisade materialen med låg kolhalt bättre nötningsmotstånd. Legeringen av bindefasmaterialet visade en ökning i ythårdhet efter efterbehandling och gjorde materialen mer nötningsbeständiga än de icke-legerade materialen. De icke-legerade materialen visade däremot på högre krosstyrka. Materialet med en järn-baserad bindefas påvisade minst ökning av ythårdheten och högst ökning samt högsta värde på krosstrykan. Samtliga material visade en förfining av WC kornen och en ökning av ythårdheten efter efterbehandlingen. Endast ett material indikerade omvandling från FCC till HCP, inga slutsatser kunde dras från de övriga proverna.
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Danielsson, Olivia. "Effect of carbon activity on microstructure evolution in WC-Ni cemented carbides". Thesis, KTH, Materialvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-226566.
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The aim of this work was to systematically study how the microstructure evolution is affected by the carbon activity in WC-Ni cemented carbides. Seven WC-9.59at%Ni alloys with different carbon activity were sintered at 1500 °C. From investigating these alloys, the carbon window has been experimentally evaluated using light optical microscopy and compared to theoretical carbon window calculated using Thermo-Calc. The overall microstructure of cross sections and raw surfaces have been investigated using scanning electron microscopy. Finally, the WC grain size and distribution have been evaluated using electron backscatter diffraction. It was found that the experimental carbon window was slightly wider than the theoretical carbon window. The WC grain size increased and the grain size distribution got wider with increasing carbon activity. In addition, the largest WC grains showed the largest grain growth by increasing carbon activity. By comparing the present results of grain size and distribution of WC-Ni to previous results of WC-Co, it was found that the WC grain growth was more pronounced and more influenced by the carbon activity.
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Polo, Montes Carlos A. "The effect of cementation technique on the retention of adhesively cemented prefabricated posts". Thesis, Birmingham, Ala. : University of Alabama at Birmingham, 2007. https://www.mhsl.uab.edu/dt/2007m/polomontes.pdf.
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Juirnarongrit, Teerawut. "Effect of diameter on the behavior of laterally loaded piles in weakly cemented sand /". Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC IP addresses, 2002. http://wwwlib.umi.com/cr/ucsd/fullcit?p3071009.
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Miner, Dustin David. "The Effect of Flowable Fill on the Lateral Resistance of Driven-Pile Foundations". Diss., CLICK HERE for online access, 2009. http://contentdm.lib.byu.edu/ETD/image/etd3308.pdf.
Pełny tekst źródłaKsiążki na temat "Effect of Cemented Fill"
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Mahal, Raj-Deep Singh. A standardized approach to determine the effect of thermocycling and long term storage on the shear bond strength of orthodontic brackets cemented to bovine enamel. [Toronto: Faculty of Dentistry, University of Toronto], 2000.
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Kodama, Yoshinori. Effect of abrasion on downstream gravel-size reduction in the Waterase River, Japan: Field work and laboratory experiment. Tsukuba, Japan: Environmental Research Center, the University of Tsukuba, 1992.
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O, Hughes William, i United States. National Aeronautics and Space Administration., red. NASA LeRC's acoustic fill effect test program and results: William O. Hughes ... [et al.] ; prepared for the 65th Shock and Vibration Symposium ; sponsored by SAVIAC, San Digeo, California, October 31-November 1994. [Washington, D.C.]: National Aeronautics and Space Administration, 1995.
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NASA LeRC's acoustic fill effect test program and results: William O. Hughes ... [et al.] ; prepared for the 65th Shock and Vibration Symposium ; sponsored by SAVIAC, San Digeo, California, October 31-November 1994. [Washington, D.C.]: National Aeronautics and Space Administration, 1995.
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Farquhar-Smith, Paul. The key role of nerve growth factor in inflammatory pain processing. Redaktorzy Paul Farquhar-Smith, Pierre Beaulieu i Sian Jagger. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780198834359.003.0021.
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This paper was one of several that cemented the key role of nerve growth factor (NGF) in sensory neurons in inflammatory pain processing. It used a novel way of biologically ‘removing’ NGF using a sequestration molecule that could then investigate the effect of the absence of NGF in pain paradigms. These data contributed to the robust evidence base indicating the importance of NGF and, although there had been issues in developing usable anti-NGF moieties in human pain conditions, this study could be considered part of the journey that has led to the introduction of antagonists to NGF actions for the treatment of pain in bone.
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Eisenberg, Melvin A. Incomplete Contracts. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780199731404.003.0036.
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Chapter 36 considers issues that result from the incompleteness of a contract. In economic theory a complete contract is a contract that specifies the parties’ rights, duties, and remedies under every possible state of the world. Under this conception every contract is incomplete, because it would be prohibitively expensive to delineate the effect of all possible future states and the consequences of each state. In contract law the term incomplete contract means a contract that is gappy or indefinite in important respects. The law on incomplete contracts concerns when a contract has too many gaps or is too indefinite to enforce, when and how a court should fill gaps in a contract, what is the effect of a provision in an agreement that contemplates the later execution of a final contract, and when is there a duty to negotiate in good faith to make an incomplete contract sufficiently complete or to reach a contemplated final contract.
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Waldmann, Michael R., red. The Oxford Handbook of Causal Reasoning. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199399550.001.0001.
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Causal reasoning is one of our most central cognitive competencies, enabling us to adapt to our world. Causal knowledge allows us to predict future events, or diagnose the causes of observed facts. We plan actions and solve problems using knowledge about cause-effect relations. Without our ability to discover and empirically test causal theories, we would not have made progress in various empirical sciences. In the past decades, the important role of causal knowledge has been discovered in many areas of cognitive psychology. Despite the ubiquity of causal reasoning, textbooks of cognitive psychology have neglected this growing field. The goal of The Oxford Handbook of Causal Reasoning is to fill this gap. The handbook brings together the leading researchers in the field of causal reasoning and offers state-of-the-art presentations of theories and research. It provides introductions of competing theories of causal reasoning, and discusses its role in various cognitive functions and domains. The final section presents research from neighboring fields.
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Wilsey, Brian J. Trophic Cascades in Grasslands. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198744511.003.0005.
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Top predators have effects that can ‘cascade down’ on lower trophic levels. Because of this cascading effect, it matters how many trophic levels are present. Predators are either ‘sit and wait’ or ‘active’. Wolves are top predators in temperate grasslands and can alter species composition of smaller-sized predators, prey, and woody and herbaceous plant species, either through direct effects or indirect effects (‘Ecology of Fear’). In human derived grasslands, invertebrate predators fill a similar ecological role as wolves. Migrating populations of herbivores tend to be more limited by food than non-migratory populations. The phenology and synchrony of births vary among prey species in a way that is consistent with an adaptation to predation. Precocious species have highly synchronous birth dates to satiate predators. Non-precocious species (‘hiders’) have asynchronous births. Results from studies that manipulate both predators and food support the hypothesis that bottom-up and top-down effects interact.
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Irvin, Sherri. Immaterial. Oxford University Press, 2022. http://dx.doi.org/10.1093/oso/9780199688210.001.0001.
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Contemporary art can seem chaotic: it may be made of toilet paper, or candies you can eat, or meat that is thrown out after each exhibition. Some works fill a room with obsessively fabricated objects, while others purport to include only concepts, thoughts or language. I argue, through many examples, that disparate developments in installation art, conceptual art, time-based media art, and participatory art can be understood in terms of custom rules. Many artists articulate custom rules governing artwork display, preservation of material elements, and interactivity or audience participation. Rules are established through the artist’s sanction: the creative act of designating the material elements and rules that constitute the work’s structure. Rules serve as medium: they are part of the work’s structure and help to constitute its meanings. Rules are meaningful in themselves, and they help to activate the expressive potential of material objects. Museum practice should include providing information about the rules; otherwise, audiences can’t fully appreciate the work. Contemporary art conservation involves preserving information: loss of information about the rules, like loss of a chunk of marble, can seriously damage the work. Rules are trickier to pin down than material objects and are subject to violation, so we’ll examine the effects on the work’s integrity and authenticity when things go wrong in various ways. Is the emergence of custom rules a positive development? Some artists have used rules to powerful effect. But rules aren’t always used well: bad art can take any form.
Części książek na temat "Effect of Cemented Fill"
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Sture, S., A. Alqasabi i M. Ayari. "Fracture and size effect characters of cemented sand". W Fracture Scaling, 405–33. Dordrecht: Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-011-4659-3_23.
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Yu, Z., H. Jing, Y. Gao, X. Wei i A. Wang. "Effect of Carbon Nanotubes on the Acoustic Emission Characteristics of Cemented Rockfill". W Lecture Notes in Civil Engineering, 513–19. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-3330-3_54.
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AbstractThe use of carbon nanotubes (CNTs) to reinforce cemented rockfill is attracting considerable interest due to the remarkable improvement in performance and the extremely low dose of the added nanomaterial. To reveal the enhancement mechanism of the CNTs on cemented rockfill, the acoustic emission (AE) characteristics of cemented rockfill specimens during the Brazilian split test were investigated. The results demonstrated that CNTs improved tensile strength by 17.2% and decreased the AE count. The nucleation and micropore-filling effects of the CNTs promoted the cement hydration reaction and formation of a denser structure, thereby improving resistance to loads. Meanwhile, finer pores avoid stress concentration, resulting in AE activity becoming more sparse. Finally, the AE b-value increased by 14.8%, which further indicated that the overall failure process was at a lower intensity.
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Tran, Khiem Quang, Tomoaki Satomi i Hiroshi Takahashi. "Study on Effect of Cornsilk Fiber in Cemented Soil Stabilization". W Lecture Notes in Civil Engineering, 571–79. Singapore: Springer Singapore, 2017. http://dx.doi.org/10.1007/978-981-10-6713-6_56.
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Chegenizadeh, A., M. Keramatikerman, S. Miceli, H. Nikraz i A. S. Sabbar. "Recycled Sawdust Effect on Controlling Sulphate Attack in Cemented Clay". W Environmental Science and Engineering, 65–88. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-94234-2_5.
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Schulz, Brett M., William M. Carty i Nikalos J. Ninos. "Effect of Die Fill on Compaction of Granular Bodies". W Whitewares and Materials: Ceramic Engineering and Science Proceedings, Volume 25, Issue 2, 61–80. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2008. http://dx.doi.org/10.1002/9780470291177.ch10.
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Kumar, Ajay, Rajesh Ghosh i Rajeev Kumar. "Effect of Implant Materials on Bone Remodelling Around Cemented Acetabular Cup". W Lecture Notes in Mechanical Engineering, 17–26. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-0550-5_3.
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Soulié, Fabien, Moulay Saïd El Youssoufi, Jean-Yves Delenne i Christian Saix. "Effect of Capillary and Cemented Bonds on the Strength of Unsaturated Sands". W Springer Proceedings in Physics, 185–93. Berlin, Heidelberg: Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/3-540-69873-6_18.
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Wang, Zhiqiang, Junjie Fan, Shijie Cui i Wenbin Xiao. "Analysis of influence effect of widening subgrade fill width on deformation". W Civil Engineering and Urban Research, Volume 1, 432–37. London: CRC Press, 2023. http://dx.doi.org/10.1201/9781003334064-57.
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Quinlan, Taylor, Alan Lloyd i Sajjadul Haque. "Effect of Core Fill Timing on Shear Capacity in Hollow-Core Slabs". W Lecture Notes in Civil Engineering, 359–69. Singapore: Springer Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-0656-5_30.
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Sulaiman, Albert, Wati A. Pranoto, Tati Zera i Mouli De Rizka Dewantoro. "Nonlinear Effect of Fluid–Structure Interaction Modeling in the Rock-Fill Dam Jatiluhur". W Lecture Notes in Civil Engineering, 49–58. Singapore: Springer Singapore, 2022. http://dx.doi.org/10.1007/978-981-16-7949-0_5.
Pełny tekst źródłaStreszczenia konferencji na temat "Effect of Cemented Fill"
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Nun˜o, N. "Effect of Tapered Geometry on the Load Transfer of an Idealized Cemented Hip Implant". W ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-32616.
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Implant looseining of cemented hip implants is one of the major causes of failure of the arthroplasty. In cemented hip implants, the polymethyl methacrylate (PMMA), also called bone cement, is used as grouting material between the stem and the surrounding bone. During polymerisation of the cement, residual stresses are generated in the bulk cement. The bone cement does not have a chemical bond with the stem nor the bone; however, it fills completely the space between the two and serves to distribute the load being transferred from the stem to the bone. Numerical analyses on the load transfer of cemented hip implants usually do not include the residual stresses due to cement curing at the stem-cement interface [1–2].
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Nun˜o, N. "Effect of Tapered Geometry on the Load Transfer of an Idealized Cemented Hip Implant". W ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-33032.
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Implant loosening of cemented hip implants is one of the major causes of failure of the arthroplasty. In cemented hip implants, the polymethyl methacrylate (PMMA), also called bone cement, is used as grouting material between the stem and the surrounding bone. During polymerisation of the cement, residual stresses are generated in the bulk cement. The bone cement does not have a chemical bond with the stem nor the bone; however, it fills completely the space between the two and serves to distribute the load being transferred from the stem to the bone. Numerical analyses on the load transfer of cemented hip implants usually do not include the residual stresses due to cement curing at the stem-cement interface [1–2].
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Kumar, Animesh, Devesh Bhaisora i Mikhil Dange. "Effect of Nanocellulose in Cement Systems". W Abu Dhabi International Petroleum Exhibition & Conference. SPE, 2021. http://dx.doi.org/10.2118/207919-ms.
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Abstract Cellulose, the one of the most abundant biomaterials available in nature, is a polymer with cellobiose as the smallest repeating unit, with a degree of polymerization that can go up to 1000 for wood cellulose. The strength-to-weight ratio of nanocellulose is eight times greater than steel (Patchiya Phanthong et al). Nanocellulose in suspension (NCS) at a varied concentration helps increase properties of cement without changing the density of the cement slurry. Being mindful of challenges in oil and gas wells, efforts were made to enhance cement properties using nanocellulose within conventional and water-extended cement systems. Samples of 15.8-ppg conventional and 12 ppg water-extended cements were prepared by varying the proportion of nanocellulose within an aqueous suspension. Rheology, sedimentation, compressive strength and mechanical properties were analyzed for a conventional 15.8-ppg cement system with varying NCS proportions of 0, 2, 4, and 5% by weight of cement (BWOC). Similar work was performed for a 12 ppg water-extended cement system by varying NCS differently in proportions of 0, 5, 10, and 20% BWOC. Two-inch cubes were set at 170°F for 24 hours for each sample. They were crushed using hydraulic crush compressive strength equipment, and the force used to break the sample was recorded. Compressive strength for this cement system was measured to be 2450, 3250, 3450, and 3875 psi, respectively, for samples with 0, 2, 4, and 5% BWOC concentrations of NCS. An increase in the strength of cement with an increase in NCS percentage was observed for the 15.8-ppg slurry design, which may be attributed to the size and shape of the NCS. However, similar study carried out with 12 ppg water extended slurries showed decrease in overall compressive strength. Nano-sized particles fill the pores within the sample, impacting structural network development. Additionally, cellulose, having a fiber-like structure, may provide inter-particulate reinforcement. Based on the results of the 15.8-ppg cement system and the high tensile strength of nanocellulose, it can be determined that NCS has a positive effect for increasing mechanical properties. By applying nanocellulose, a tailored cement system (dependable barrier) can be designed to minimize risk and maximize production from oil and gas wells. Nanocellulose is of increasing interest for a range of applications relevant to the fields of material science and biomedical engineering because of its renewable nature, anisotropic shape, excellent mechanical properties, good biocompatibility, tailorable surface chemistry, and interesting optical properties. Low-volume NCS additions can alter the structure of the cured cement system and increase its mechanical properties. This reinforcing mechanism may provide a new opportunity for achieving higher strength cementitious materials.
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Haan, John. "Comparison of cemented paste backfill and cemented rock fill systems". W 14th International Seminar on Paste and Thickened Tailings. Australian Centre for Geomechanics, Perth, 2011. http://dx.doi.org/10.36487/acg_rep/1104_44_haan.
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Martic, Zlatko, John Gelson, Hugo Brás, Qi Xu i William Brosko. "New perspectives for cemented hydraulic fill with chemical technologies". W Eleventh International Symposium on Mining with Backfill. Australian Centre for Geomechanics, Perth, 2014. http://dx.doi.org/10.36487/acg_rep/1404_23_martic.
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Ali, Ahmed, Ahmed Abdulhamid Mahmoud, Mustafa Al Ramadan i Salaheldin Elkatatny. "The Effect of the Olive Waste on the Rheological Properties, Thickening Time, Permeability, and Strength of Oil Well Cement". W 57th U.S. Rock Mechanics/Geomechanics Symposium. ARMA, 2023. http://dx.doi.org/10.56952/arma-2023-0734.
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ABSTRACT In the oil and gas industry, cementing is a very important process to maintain the stability of the well. The cement slurry is injected downhole to fit the annulus between the casing and formation which in further can perform as an effective plug against fluids movement and at the same time supports the casing. In the design of the cement slurry, different types of additives are used based on operation conditions, incorporation of a new additive considerably affects all properties of the cement slurry and the solidified sheath. In this work, lab experiments were performed to investigate the effect of olive waste on Saudi Class G cement properties, the possibility of replacing the commercial retarder with olive waste was also studied in this work. Five samples with different olive waste content were prepared, and the rheological characteristics, thickening time, mechanical properties, and permeability of the samples were evaluated after 24 hours of curing at 95 °C. The results indicated that olive waste was able to replace the use of a commercial retarder. The addition of olive waste did not affect the cement plastic viscosity, while the yield point, 10-sec and 10-min gel strength of the cement were considerably increased with the increase in the olive waste content. The cement compressive strength was also increased with the incorporation of olive waste of a maximum of 0.375 %, and the permeability was decreasing with the addition of a maximum of 0.25 % olive waste. INTRODUCTION In the oil & gas industry, well cementing is an important operation to maintain the stability of the wellbore during drilling operations or production periods. In the cementing process, cement is pumped down the wellbore to fill the annulus between the casing and borehole (Adams & Charrier, 1985; Mitchell, 2006; Nelson & Guillot, 2006a; Hossain & Al-Majed, 2015). This cement can play significant roles and is used to achieve many functions such as providing a barrier between the formation and the wellbore, preventing fluid migration, and supporting the well casing (Al Ramadan et al., 2019, 2021; Fakoya & Shah, 2017; Jorge & Sampaio, 2007).
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Guo, Li Jie, Xiaocong Yang i Xie Lianku. "An experimental study on the mechanical properties of cemented rock – tailings fill". W Thirteenth International Seminar on Paste and Thickened Tailings. Australian Centre for Geomechanics, Perth, 2010. http://dx.doi.org/10.36487/acg_rep/1063_41_guo.
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Karki, Kailash C., Suhas V. Patankar i Jeff Grant. "Simulation of Fluid Flow, Combustion, and Heat Transfer in a Coal-Fired Cement Kiln". W ASME 2000 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/imece2000-1662.
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Abstract This paper presents the details of a mathematical model for fluid flow, combustion, and heat transfer in cement kilns. The model is based on the finite-volume technique for the solution of the gas-phase equations. The k-ε model is used to represent the turbulence effects. A two-step kinetics scheme is employed to simulate the gas-phase combustion. The Lagrangian formulation is employed for the particle phase, and the coupling between the particle and gas phases is handled by introducing appropriate source terms in the gas-phase equations. The particle reaction model includes coal devolatilization and char oxidation. The radiation heat transfer in the kiln is modeled using the six-flux model. The feed bed is represented as a solid region that is moving in the axial direction with a uniform velocity, which is calculated from the feed rate, feed density, and the fill area. The effect of chemical reactions in the feed bed is modeled by including temperature-dependent heat release/absorption rates in the energy equation. The model has been applied to a cement kiln in operation. The predicted results agree with the observations and experience for the kiln.
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Liston, David. "Utilisation of cemented rockfill, cemented hydraulic fill and paste to successfully achieve ore production expansion to 2 Mtpa at Chelopech Mine". W Eleventh International Symposium on Mining with Backfill. Australian Centre for Geomechanics, Perth, 2014. http://dx.doi.org/10.36487/acg_rep/1404_32_liston.
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Turichshev, Alexandr, Luigi Cotesta, Richard Brummer i Marc Beauvais. "Estimation of fill strength requirements using bonded particle modelling for mining under cemented rockfill". W First International Conference on Underground Mining Technology. Australian Centre for Geomechanics, Perth, 2017. http://dx.doi.org/10.36487/acg_rep/1710_30_turichshev.
Pełny tekst źródłaRaporty organizacyjne na temat "Effect of Cemented Fill"
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Long, Wendy, Jesse Doyle, Edith Martinez-Guerra i Christopher Griggs. Effects of impure water sources on early-age properties of calcium sulfoaluminate cements for rapid airfield damage recovery. Engineer Research and Development Center (U.S.), lipiec 2022. http://dx.doi.org/10.21079/11681/44780.
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In austere environments with limited access to clean water, it is advantageous to use nonpotable water for construction (i.e., mixing water for concrete.) In rapid-response situations such as rapid airfield damage recovery (RADR), the use of calcium sulfoaluminate (CSA) cements is beneficial for expedient pavement repairs because of their rapid strength gain characteristics. However, the hydration products formed by CSA cements are substantially different from those formed by ordinary portland cement and might react differently to impurities that water sources may contain. A laboratory study component investigated the application of various salts and impure sources of mixing water with commercially available CSA cement-based products. A field component studied the application of naturally occurring impure water sources for RADR. Recommendations are made for implementation of impure mixing water for RADR using commercially available flowable fill and concrete products made with CSA cement.
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Kitai, Takashi, Hiroyuki Uchida i Masahiro Watanabe. Evaluation of the performance degradation at PAFC effect of electrolyte fill-level on electrode performance. Office of Scientific and Technical Information (OSTI), grudzień 1996. http://dx.doi.org/10.2172/460208.
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Quinn, Meghan. Geotechnical effects on fiber optic distributed acoustic sensing performance. Engineer Research and Development Center (U.S.), lipiec 2021. http://dx.doi.org/10.21079/11681/41325.
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Distributed Acoustic Sensing (DAS) is a fiber optic sensing system that is used for vibration monitoring. At a minimum, DAS is composed of a fiber optic cable and an optic analyzer called an interrogator. The oil and gas industry has used DAS for over a decade to monitor infrastructure such as pipelines for leaks, and in recent years changes in DAS performance over time have been observed for DAS arrays that are buried in the ground. This dissertation investigates the effect that soil type, soil temperature, soil moisture, time in-situ, and vehicle loading have on DAS performance for fiber optic cables buried in soil. This was accomplished through a field testing program involving two newly installed DAS arrays. For the first installation, a new portion of DAS array was added to an existing DAS array installed a decade prior. The new portion of the DAS array was installed in four different soil types: native fill, sand, gravel, and an excavatable flowable fill. Soil moisture and temperature sensors were buried adjacent to the fiber optic cable to monitor seasonal environmental changes over time. Periodic impact testing was performed at set locations along the DAS array for over one year. A second, temporary DAS array was installed to test the effect of vehicle loading on DAS performance. Signal to Noise Ratio (SNR) of the DAS response was used for all the tests to evaluate the system performance. The results of the impact testing program indicated that the portions of the array in gravel performed more consistently over time. Changes in soil moisture or soil temperature did not appear to affect DAS performance. The results also indicated that time DAS performance does change somewhat over time. Performance variance increased in new portions of array in all material types through time. The SNR in portions of the DAS array in native silty sand material dropped slightly, while the SNR in portions of the array in sand fill and flowable fill material decreased significantly over time. This significant change in performance occurred while testing halted from March 2020 to August 2020 due to the Covid-19 pandemic. These significant changes in performance were observed in the new portion of test bed, while the performance of the prior installation remained consistent. It may be that, after some time in-situ, SNR in a DAS array will reach a steady state. Though it is unfortunate that testing was on pause while changes in DAS performance developed, the observed changes emphasize the potential of DAS to be used for infrastructure change-detection monitoring. In the temporary test bed, increasing vehicle loads were observed to increase DAS performance, although there was considerable variability in the measured SNR. The significant variation in DAS response is likely due to various industrial activities on-site and some disturbance to the array while on-boarding and off-boarding vehicles. The results of this experiment indicated that the presence of load on less than 10% of an array channel length may improve DAS performance. Overall, this dissertation provides guidance that can help inform the civil engineering community with respect to installation design recommendations related to DAS used for infrastructure monitoring.
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Leonardo, Fabio Morales, Carlos Ospino i Amaral Nicole. Online Vacancies and its Role in Labor Market Performance. Banco de la República, wrzesień 2021. http://dx.doi.org/10.32468/be.1174.
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This paper assesses whether the expansion of online job vacancies leads to a more efficient labor market. We provide compelling evidence that the increase in online job vacancy penetration in Colombia has had an enhancing effect on the labor market's efficiency by making it easier for firms to find workers to fill their job openings. An estimation of the Beveridge Curve (unemployment to vacancies relationship), a well-established theoretical development from search models, concludes that policies that increase online vacancy posting enhance efficiency. We implement a differences in differences design to take advantage of a regulation, which mandates that all authorized online vacancy providers report any online vacancy to the Public Employment Service in Colombia. We find that sub-segments of the labor market with a relevant fraction of their vacancies posted online, presented on average nearly 15% lower vacancy rate for a given unemployment rate. Therefore, for these sub-segments, the Beveridge curve shifted inwards due to efficiency enhancements. These findings support active search policies to reduce information barriers, which reduce the odds of firms and workers finding one other in the labor market. Policies as those implemented by the Public Employment Service in Colombia seem to be beneficial.
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Weiss. PR-318-08700-R01 Smart Gas-Using Chemicals to Improve Gas Deliverability-Phase II. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), marzec 2009. http://dx.doi.org/10.55274/r0010944.
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In water-wet gas storage reservoirs, the imbibition force promotes the retention of water in the pore space, which curtails the deliverability of gas to the wellbore during periods of high demand. Similarly, the injection of gas during the fill cycle is restricted. In addition, the pore space occupied by irreducible water is not available to hold gas. The objective of this Phase II project was to demonstrate in the field the new technology developed in the laboratory during Phase I. Wettability alteration was evaluated as a technique to improve gas deliverability from gas storage wells during Phase I. During the first year, two cost-effective surfactants were selected from 11 candidates through various laboratory screening and reservoir core tests. Reservoir cores from three gas storage facilities including sandstone and dolomite reservoirs were used to evaluate the two surfactants. The imbibition and core flood tests showed that gas deliverability and storage capacity were improved in surfactant-treated sandstone cores. However, these surfactants had a very limited effect on dolomite cores. An engineering analysis was conducted to develop an analytical method for evaluating future field tests of the new technology. It was concluded that the aquifer storage facilities are candidates for field testing. Results from Phase I provided the foundation for this Phase II project.
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Hovav, Ran, Peggy Ozias-Akins i Scott A. Jackson. The genetics of pod-filling in peanut under water-limiting conditions. United States Department of Agriculture, styczeń 2012. http://dx.doi.org/10.32747/2012.7597923.bard.
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Pod-filling, an important yield-determining stage is strongly influenced by water stress. This is particularly true for peanut (Arachishypogaea), wherein pods are developed underground and are directly affected by the water condition. Pod-filling in peanut has a significant genetic component as well, since genotypes are considerably varied in their pod-fill (PF) and seed-fill (SF) potential. The goals of this research were to: Examine the effects of genotype, irrigation, and genotype X irrigation on PF and SF. Detect global changes in mRNA and metabolites levels that accompany PF and SF. Explore the response of the duplicate peanut pod transcriptome to drought stress. Study how entire duplicated PF regulatory processes are networked within a polyploid organism. Discover locus-specific SNP markers and map pod quality traits under different environments. The research included genotypes and segregating populations from Israel and US that are varied in PF, SF and their tolerance to water deficit. Initially, an extensive field trial was conducted to investigate the effects of genotype, irrigation, and genotype X irrigation on PF and SF. Significant irrigation and genotypic effect was observed for the two main PF related traits, "seed ratio" and "dead-end ratio", demonstrating that reduction in irrigation directly influences the developing pods as a result of low water potential. Although the Irrigation × Genotype interaction was not statistically significant, one genotype (line 53) was found to be more sensitive to low irrigation treatments. Two RNAseq studies were simultaneously conducted in IL and the USA to characterize expression changes that accompany shell ("source") and seed ("sink") biogenesis in peanut. Both studies showed that SF and PF processes are very dynamic and undergo very rapid change in the accumulation of RNA, nutrients, and oil. Some genotypes differ in transcript accumulation rates, which can explain their difference in SF and PF potential; like cvHanoch that was found to be more enriched than line 53 in processes involving the generation of metabolites and energy at the beginning of seed development. Interestingly, an opposite situation was found in pericarp development, wherein rapid cell wall maturation processes were up-regulated in line 53. Although no significant effect was found for the irrigation level on seed transcriptome in general, and particularly on subgenomic assignment (that was found almost comparable to a 1:1 for A- and B- subgenomes), more specific homoeologous expression changes associated with particular biosynthesis pathways were found. For example, some significant A- and B- biases were observed in particular parts of the oil related gene expression network and several candidate genes with potential influence on oil content and SF were further examined. Substation achievement of the current program was the development and application of new SNP detection and mapping methods for peanut. Two major efforts on this direction were performed. In IL, a GBS approach was developed to map pod quality traits on Hanoch X 53 F2/F3 generations. Although the GBS approach was found to be less effective for our genetic system, it still succeeded to find significant mapping locations for several traits like testa color (linkage A10), number of seeds/pods (A5) and pod wart resistance (B7). In the USA, a SNP array was developed and applied for peanut, which is based on whole genome re-sequencing of 20 genotypes. This chip was used to map pod quality related traits in a Tifrunner x NC3033 RIL population. It was phenotyped for three years, including a new x-ray method to phenotype seed-fill and seed density. The total map size was 1229.7 cM with 1320 markers assigned. Based on this linkage map, 21 QTLs were identified for the traits 16/64 weight, kernel percentage, seed and pod weight, double pod and pod area. Collectively, this research serves as the first fundamental effort in peanut for understanding the PF and SF components, as a whole, and as influenced by the irrigation level. Results of the proposed study will also generate information and materials that will benefit peanut breeding by facilitating selection for reduced linkage drag during introgression of disease resistance traits into elite cultivars. BARD Report - Project4540 Page 2 of 10
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Charatsi, Dimitra, Polyxeni Vanakara, Michail Nikolaou, Aikaterini Evaggelopoulou, Dimitrios Korfias, Foteini Simopoulou, Nikolaos Charalampakis i in. Vaginal Dilator Use to Promote Sexual Wellbeing After Radiotherapy in Gynaecological Cancer Survivors: A Prospective Observational Study. Science Repository, październik 2021. http://dx.doi.org/10.31487/j.ijcst.2021.03.01.sup.
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Background: Since continuing advances in radiotherapy technology broaden the role of radiotherapy in the treatment of gynaecologic malignancies, the use of vaginal dilators has been introduced in order to mitigate the risk of vaginal stenosis. The main aims of this study were to investigate the vaginal dilator use efficacy in the treatment of radiation-induced vaginal stenosis and the vaginal dilator effect on sexual quality of life. Methods: We studied fifty-three patients with endometrial or cervical cancer. The participants were treated with radical or adjuvant external beam radiotherapy and/or brachytherapy. They were routinely examined at four time points post-radiotherapy when also they were asked to fill in a validated sexual function-vaginal changes questionnaire. A p-value less than 0.05 was considered statistically significant. Results: The vaginal stenosis grading score was decreased and the size of the vaginal dilator comfortably insertable was gradually increased throughout the year of vaginal dilator use while radiation-induced vaginal and sexual symptoms were improved throughout the year of VD use. All patients with initial grade 3 showed vaginal stenosis of grade 2 after 12 months of vaginal dilator use and 65.8% of the patients with grade 2 initial vaginal stenosis demonstrated final vaginal stenosis grade 1 while 77.8% of the participants with initial 1st size of vaginal dilators reached the 3rd vaginal dilator size after 12 months. Starting time of dilator therapy <= 3 months after the end of radiotherapy was associated with a significant decrease in vaginal stenosis. Additionally, there was an overall upward trend regarding patients’ satisfaction with their sexual life. Conclusion: Endometrial and cervical cancer survivors should be encouraged to use vaginal dilators for the treatment of vaginal stenosis and sexual rehabilitation after radiotherapy.
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Bendikov, Michael, i Thomas C. Harmon. Development of Agricultural Sensors Based on Conductive Polymers. United States Department of Agriculture, sierpień 2006. http://dx.doi.org/10.32747/2006.7591738.bard.
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In this 1-year feasibility study, we tried polymerization of several different monomers, commercial as well as novel, specially designed and synthesized for this project in the presence of the nitrate ion to produce imprinted conductive polymers. Polymers 1 and 2 (shown below) produced a response to nitrate, but one inferior to that produced by a polypyrrole (Ppy)-based sensor (which we demonstrated prior to this study). Thus, we elected to proceed with improving the stability of the Ppy-based sensor. In order to improve stability of the Ppy-based sensor, we created a two-layer design which includes nitrate-doped Ppy as an inner layer, and nitrate-doped PEDOT as the outer layer. PEDOT is known for its high environmental stability and conductivity. This design has demonstrated promise, but is still undergoing optimization and stability testing. Previously we had failed to create nitrate-doped PEDOT in the absence of a Ppy layer. Nitrate-doped PEDOT should be very promising for sensor applications due to its high stability and exceptional sensing properties as we showed previously for sensing of perchlorate ions (by perchlorate-doped PEDOT). During this year, we have succeeded in preparing nitrate-doped PEDOT (4 below) by designing a new starting monomer (compound 3 below) for polymerization. We are currently testing this design for nitrate sensing. In parallel with the fabrication design studies, we fabricated and tested nitrate-doped Ppy sensors in a series of flow studies under laboratory and field conditions. Nitrate-doped Ppy sensors are less stable than is desirable but provide excellent nitrate sensing characteristics for the short-term experiments focusing on packaging and deployment strategies. The fabricated sensors were successfully interfaced with a commercial battery-powered self-logging (Onset Computer Hobo Datalogger) and a wireless data acquisition and transmission system (Crossbow Technologies MDA300 sensor interface and Mica2 wireless mote). In a series of flow-through experiments with water, the nitrate-doped Ppy sensors were exposed to pulses of dissolved nitrate and compared favorably with an expensive commercial sensor. In 24-hour field tests in both Merced and in Palmdale, CA agricultural soils, the sensors responded to introduced nitrate pulses, but with different dynamics relative to the larger commercial sensors. These experiments are on-going but suggest a form factor (size, shape) effect of the sensor when deployed in a porous medium such as soil. To fill the need for a miniature reference electrode, we identified and tested one commercial version (Cypress Systems, ESA Mini-reference electrode) which works well but is expensive ($190). To create an inexpensive miniature reference electrode, we are exploring the use of AgCl-coated silver wire. This electrode is not a “true” reference electrode; however, it can calibrated once versus a commercial reference electrode at the time of deployment in soil. Thus, only one commercial reference electrode would suffice to support a multiple sensor deployment.
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Droby, Samir, Joseph W. Eckert, Shulamit Manulis i Rajesh K. Mehra. Ecology, Population Dynamics and Genetic Diversity of Epiphytic Yeast Antagonists of Postharvest Diseases of Fruits. United States Department of Agriculture, październik 1994. http://dx.doi.org/10.32747/1994.7568777.bard.
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One of the emerging technologies is the use of microbial agents for the control of postharvest diseases of fruits and vegetables. A number of antagonistic microorganisms have been discovered which have the potential to effectively control postharvest diseases. Some of this technology has been patented and commercial products such as AspireTM (Ecogen Corporatin, Langhorne, PA, USA), Biosave 10TM and Biosave 11TM (Ecoscience Inc., Worchester, MA, USA) have been registered for commercial use. The principal investigator of this project was involved in developing the yeast-based biofungicide-AspireTM and testing its efficacy under commercial conditions. This research project was initiated to fill the gap between the knowledge available on development and commercial implementation of yeast biocontrol agents and basic understanding of various aspects related to introducing yeast antagonists to fruit surfaces, along with verification of population genetics. The main objectives of this study were: Study ecology, population dynamics and genetic diversity of the yeast antagonists Candida guilliermondii, C. oleophila, and Debaryomyces hansenii, and study the effect of preharvest application of the yeast antagonist C. oleophila naturally occurring epiphytic microbial population and on the development of postharvest diseases of citrus fruit during storage. Our findings, which were detailed in several publications, have shown that an epiphytic yeast population of grapefruit able to grow under high osmotic conditions and a wide range of temperatures was isolated and characterized for its biocontrol activity against green mold decay caused by Penicillium digitatum. Techniques based on random amplified polymorphic DNA (RAPD) and arbitrary primed polymerase chain reaction (ap-PCR), as well as homologies between sequences of the rDNA internal transcribed spacers (ITS) and 5.8S gene, were used to characterize the composition of the yeast population and to determine the genetic relationship among predominant yeast species. Epiphytic yeasts exhibiting the highest biocontrol activity against P. digitatum on grapefruit were identified as Candida guilliermondii, C. oleophila, C. sake, and Debaryomyces hansenii, while C. guilliermondii was the most predominant species. RAPD and ap-PCR analysis of the osmotolerant yeast population showed two different, major groups. The sequences of the ITS regions and the 5.8S gene of the yeast isolates, previously identified as belonging to different species, were found to be identical. Following the need to develop a genetically marked strain of the yeast C. oleophila, to be used in population dynamics studies, a transformation system for the yeast was developed. Histidine auxotrophy of C. oloephila produced using ethyl methanesulfonate were transformed with plasmids containing HIS3, HIS4 and HIS5 genes from Saccharomyces cerevisiae. In one mutant histidin auxotrophy was complemented by the HIS5 gene of S. cerevisiae is functionally homologous to the HIS5 gene in V. oleophila. Southern blot analysis showed that the plasmid containing the S. cerevisiae HIS5 gene was integrated at a different location every C. oleophila HIS+ transformant. There were no detectable physiological differences between C. oleophila strain I-182 and the transformants. The biological control ability of C. oleophila was not affected by the transformation. A genetically marked (with b-glucuronidase gene) transformant of C. oleophila colonized wounds on orange fruits and its population increased under field conditions. Effect of preharvest application of the yeast C. oleophila on population dynamics of epiphytic microbial population on wounded and unwounded grapefruit surface in the orchard and after harvest was also studied. In addition, the effect of preharvest application of the yeast C. oleophila on the development of postharvest decay was evaluated. Population studies conducted in the orchard showed that in control, non-treated fruit, colonization of wounded and unwounded grapefruit surface by naturally occurring filamentous fungi did not vary throughout the incubation period on the tree. On the other hand, colonization of intact and wounded fruit surface by naturally occurring yeasts was different. Yeasts colonized wounded surface rapidly and increased in numbers to about two orders of magnitude as compared to unwounded surface. On fruit treated with the yeast and kept on the tree, a different picture of fungal and yeast population had emerged. The detected fungal population on the yeast-treated intact surface was dramatically reduced and in treated wounds no fungi was detected. Yeast population on intact surface was relatively high immediately after the application of AspireTM and decreased to than 70% of that detected initially. In wounds, yeast population increased from 2.5 x 104 to about 4x106 after 72 hours of incubation at 20oC. Results of tests conducted to evaluate the effect of preharvest application of AspireTM on the development of postharvest decay indicated the validity of the approach.