Articoli di riviste: "Top-Bar effect"

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Skrodzka, Ewa B., Bogumił B. J. Linde e Antoni Krupa. "Effect of Bass Bar Tension on Modal Parameters of a Violin's Top Plate". Archives of Acoustics 39, n. 1 (1 marzo 2015): 145–49. http://dx.doi.org/10.2478/aoa-2014-0015.

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Abstract Experimental modal analysis of a violin with three different tensions of a bass bar has been performed. The bass bar tension is the only intentionally introduced modification of the instrument. The aim of the study was to find differences and similarities between top plate modal parameters determined by a bass bar perfectly fitting the shape of the top plate, the bass bar with a tension usually applied by luthiers (normal), and the tension higher than the normal value. In the modal analysis four signature modes are taken into account. Bass bar tension does not change the sequence of mode shapes. Changes in modal damping are insignificant. An increase in bass bar tension causes an increase in modal frequencies A0 and B(1+) and does not change the frequencies of modes CBR and B(1-).

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Reza Esfahani, M., M. Lachemi e M. Reza Kianoush. "Top-bar effect of steel bars in self-consolidating concrete (SCC)". Cement and Concrete Composites 30, n. 1 (gennaio 2008): 52–60. http://dx.doi.org/10.1016/j.cemconcomp.2007.05.012.

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von Grünau, Michael, Zeina Saikali e Jocelyn Faubert. "Processing Speed in the Motion-Induction Effect". Perception 24, n. 5 (maggio 1995): 477–90. http://dx.doi.org/10.1068/p240477.

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The motion-induction effect, where an illusory motion is perceived within a bar when it is shown next to a spot presented slightly earlier, was studied with respect to the idea that it is based on differential processing speeds between the two ends of the bar. First, by using just a bar with a luminance gradient, the existence of a motion illusion (gradient motion) within such a bar was demonstrated, presumably due to the different processing speeds of differential luminances. When such a bar was used in the motion-induction effect, it was shown to modulate, for short delays, the strength of the effect up or down, according to the direction of the gradient with respect to the position of the spot. When the same bar was used in the double-motion-induction effect (split priming), in which motion is usually away from the later spot, it totally determined the perceived direction of illusory motion, independently of gradient direction with respect to the later spot or the time between the two spots. These results demonstrate, on the one hand, that differential local processing speed is a likely mechanism to underlie the motion-induction effect. On the other hand, they also suggest the involvement of other more global (and perhaps top—down) processes.

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Wang, Yikuan, Abhijit Mukherjee e Arnaud Castel. "Detection of Top-Bar Effect in Reinforced Concrete Using Guided Ultrasonic Waves". Journal of Structural Engineering 147, n. 4 (aprile 2021): 04021032. http://dx.doi.org/10.1061/(asce)st.1943-541x.0002950.

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Zhao, Fang Ran, Jia Lin Cao e Ning Wang. "Analysis of Factors Influence on Void Underneath at Concrete Pavement Joints". Applied Mechanics and Materials 488-489 (gennaio 2014): 483–86. http://dx.doi.org/10.4028/www.scientific.net/amm.488-489.483.

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Three-dimensional finite element analysis was made on the transverse joint stress state of the concrete pavement slab with void underneath using ANSYS. The transfer effect of dowel bar was discussed with aircraft loaded in the joints. The influence rule of load transfer effect under different dowel bar spacing and dowel bar cross section dimension was compared. Based on the results of finite element analysis, this paper had carried on the experimental study on stress-transferring effect on concrete pavement joints with different location of the dowel bar. The influencing factors of pavement slab transverse joint with void underneath and the resistance of pavement damage on the joint was analyzed. Theoretical analysis showed that in order to reinforce the resistance capacity of local cavity on concrete pavement joint, the largest spacing of transverse dowel bar set shall not be more than 45cm, and the main factors influencing the resistance void ability on the joint are top reaction modulus, coefficient of cavity, the concrete elastic modulus and coefficient of transverse reinforcement.

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Minato, Kenichi, Tomoichiro Okamoto e Masasuke Takata. "Effect of Atmosphere on Zinc Oxide Crystal Growth by Electric Current Heating with Au Catalyst". Advanced Materials Research 11-12 (febbraio 2006): 269–72. http://dx.doi.org/10.4028/www.scientific.net/amr.11-12.269.

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We developed a new zinc oxide (ZnO) crystal growth method using Au combined with electric current heating. Au paste was placed on a ZnO ceramic bar. When a certain current flowed through the bar, the paste melted on the bar. Then crystals grew on the molten Au surface immediately. The shape of the crystals depended on the atmosphere during the growth. The whiskers with spherical top and the crystals consisting of a hexangular pyramidal base and needle head were grown on Au in air and Ar atmosphere, respectively. From cathodoluminescence at room temperature, the weak ultraviolet (UV) emission at approximately 3.2 eV and the strong visible emission at approximately 2.3 eV were observed from the whisker grown in air. The UV emission at approximately 3.3 eV dominated a spectrum from the pyramidal crystal grown in Ar atmosphere.

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Kim, Nam Yong, Dae-Cheol Ko, Yangjin Kim, Sang Wook Han, Il Yeong Oh e Young Hoon Moon. "Feasibility of Reduced Ingot Hot-Top Height for the Cost-Effective Forging of Heavy Steel Ingots". Materials 13, n. 13 (29 giugno 2020): 2916. http://dx.doi.org/10.3390/ma13132916.

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Feasibility studies have been performed on ingots with reduced hot-top heights for the cost-effective hot forging of heavy ingots. The quality of the heavy ingots is generally affected by internal voids, which have been known to be accompanied by inclusions and segregation. To guarantee the expected mechanical performance of the forged products, these voids should be closed and eliminated during the hot open die forging process. Hence, to effectively control the internal voids, the optimum hot-top height and forging schedules need to be determined. In order to improve the utilization ratio of ingots, the ingot hot-top height needs to be minimized. To investigate the effect of the reduced hot-top height on the forged products, shaft and bar products have been manufactured via hot forging of ingots having various hot-top heights. From the operational results, the present work suggests effective forging processes to produce acceptable shaft and bar products using ingots having reduced hot tops. The mechanical properties of shop-floor products manufactured from ingots with reduced hot tops have also been measured and compared with those of conventional ingot products.

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Reichardt, Elisabeth, Steffen Decker, Michel Dalstra, Prasad Nalabothu, Markus Steineck, Leandro Fernandez e Carlalberta Verna. "The Effect of Ligature Type on Lateral Tooth Movement during Orthodontic Treatment with Lingual Appliances—An In Vitro Study". Materials 15, n. 9 (7 maggio 2022): 3365. http://dx.doi.org/10.3390/ma15093365.

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(1) Background: One of the most challenging parts in lingual orthodontics is the control and correction of the tip of anterior teeth, due to the occlusal open vertical slot of the incisors in lingual systems. The presented experimental in-vitro study was performed to determine the maximal tipping moment of the anterior teeth between two types of lingual brackets, the Incognito™ Appliance System (Incognito, TOP-Service, Bad Essen, Germany) and Tip-Bar™ system (Incognito, TOP-Service, Bad Essen, Germany). Furthermore, twelve different ligation methods and two different ligature materials were investigated. (2) Methods: The measurement was performed by assessing the stiffness and ultimate strength of the ligature in a uniaxial material testing machine (Instron, Norwood, MA, USA) using a 0.025 × 0.018 inch stainless steel wire. (3) The results showed that the highest precision for control tipping of anterior teeth was determined for the 0.010 inch Stainless Steel Tie (Pelz and Partner). Furthermore, the Tip-Bar™ brackets increased the maximal moment by 33.8% for elastic and steel ligatures. (4) Conclusions: The lateral tooth movement is highly dependent on the type of ligature and applied material during orthodontic treatment with lingual appliances. The use of 0.010 inch steel ligatures and the Tip-Bar™ bracket design results in better alignment in the anterior teeth segment.

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Esfahani, M. Reza, M. Reza Kianoush e M. Lachemi. "Bond strength of glass fibre reinforced polymer reinforcing bars in normal and self-consolidating concrete". Canadian Journal of Civil Engineering 32, n. 3 (1 giugno 2005): 553–60. http://dx.doi.org/10.1139/l05-005.

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This paper presents the results of an experimental study on bond strength of reinforcing bars made of glass fibre reinforced polymers (GFRP) embedded in normal and self-consolidating concrete. The study included pull-out tests of 36 GFRP reinforcing bars embedded in concrete specimens. Different parameters such as type of concrete, bar location, and cover thickness were considered as variables in different specimens. The results showed that the type of bond failure was by splitting of concrete for all specimens. The bond strength of bottom GFRP reinforcing bars was almost the same for both normal concrete and self-consolidating concrete. For the top bars, however, the bond strength of self-consolidating concrete was less than that of normal concrete.Key words: bond strength, glass FRP, reinforcing bars, top-bar effect, self-consolidating concrete.

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Liu, Xiaochao, Wentao Li, Yunqian Zhen, Luanluan Jia, Yongzhe Li e Xianjun Pei. "Effect of Process Parameters on Weld Quality in Vortex- Friction Stir Welding of 6061-T6 Aluminum Alloy". Materials 16, n. 2 (16 gennaio 2023): 873. http://dx.doi.org/10.3390/ma16020873.

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Vortex- friction stir welding (VFSW) utilizes a stir bar made of an identical material to the workpiece to rub the workpiece’s top surface, which avoids the keyhole defect in conventional friction stir welding. It presents great potential in the repair field of aluminum alloys. In this study, the effect of stir bar diameter, rotation speed, and welding speed on the weld formation was investigated in the VFSW of 6061-T6 aluminum alloy. The weld macrostructure, penetration, and mechanical properties were characterized. The results show that a large diameter of the stir bar can enhance the vortex material flow, increase the heat input, and eliminate the incomplete-penetration defect. The increase in rotation speed within limits can enhance the weld penetration and the mechanical properties of the weld nugget zone (WNZ). However, too high a rotation speed reduces the weld penetration and weakens the mechanical properties of the WNZ. The increase in welding speed reduces the weld penetration but enhances the mechanical properties of the heat affected zone. The incomplete-penetration defect significantly weakens the ductility of the VFSW joint. It can be eliminated by enlarging the stir bar diameter and choosing a moderate rotation speed and a lower welding speed.

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Meister, Julian, Helge Fuchs, Claudia Beck, Ismail Albayrak e Robert M. Boes. "Velocity Fields at Horizontal Bar Racks as Fish Guidance Structures". Water 12, n. 1 (18 gennaio 2020): 280. http://dx.doi.org/10.3390/w12010280.

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Horizontal bar racks used as fish protection measures at hydropower plants have rapidly gained importance in recent years. Despite the large number of installed racks in Europe, systematic investigations of the hydraulic losses and velocity fields were missing. To fill these research gaps, the hydraulic performance of horizontal bar racks was systematically investigated in a laboratory flume for a large number of rack parameters and different hydropower plant layouts. The results of the head loss assessment are published in a paper entitled Head Losses of Horizontal Bar Racks as Fish Guidance Structures, whereas the present paper focuses on the velocity fields. The measurements show that the bar shape, the horizontal approach flow angle, and the clear bar spacing have only a minor effect on the velocity fields. In contrast, bottom and top overlays might enhance the fish guidance efficiency for bottom and surface oriented fish, while the asymmetric downstream velocity field can reduce turbine efficiencies. The hydropower plant layout strongly affects the approach flow field to horizontal bar racks. For block-type hydropower plants, the installation of a dividing pier or partial opening of the spillways improves the flow field for better fish guidance.

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Wolf, Christian, e Markus Lappe. "Top-down control of saccades requires inhibition of suddenly appearing stimuli". Attention, Perception, & Psychophysics 82, n. 8 (16 agosto 2020): 3863–77. http://dx.doi.org/10.3758/s13414-020-02101-3.

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Abstract Humans scan their visual environment using saccade eye movements. Where we look is influenced by bottom-up salience and top-down factors, like value. For reactive saccades in response to suddenly appearing stimuli, it has been shown that short-latency saccades are biased towards salience, and that top-down control increases with increasing latency. Here, we show, in a series of six experiments, that this transition towards top-down control is not determined by the time it takes to integrate value information into the saccade plan, but by the time it takes to inhibit suddenly appearing salient stimuli. Participants made consecutive saccades to three fixation crosses and a vertical bar consisting of a high-salient and a rewarded low-salient region. Endpoints on the bar were biased towards salience whenever it appeared or reappeared shortly before the last saccade was initiated. This was also true when the eye movement was already planned. When the location of the suddenly appearing salient region was predictable, saccades were aimed in the opposite direction to nullify this sudden onset effect. Successfully inhibiting salience, however, could only be achieved by previewing the target. These findings highlight the importance of inhibition for top-down eye-movement control.

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Şahin, İnanç. "Effect of top quark spin on the unparticle couplings in $\gamma\gamma \to t\bar{t}$". European Physical Journal C 60, n. 3 (19 febbraio 2009): 431–39. http://dx.doi.org/10.1140/epjc/s10052-009-0896-3.

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Opatowicz, Dominika, Urszula Radoń e Paweł Zabojszcza. "Assessment of the Effect of Wind Load on the Load Capacity of a Single-Layer Bar Dome". Buildings 10, n. 10 (13 ottobre 2020): 179. http://dx.doi.org/10.3390/buildings10100179.

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The main purpose of the paper was the assessment of the effect of wind load on the load capacity of a single-layer bar dome. Additionally, which numerical method is appropriate for low-rise single-layer bar domes was checked. In order to explain the effect of the height-to-span ratio on the selection of the appropriate calculation model and method of analysis of the bar dome, an example of the known von Mises truss was proposed. Two cases of von Mises truss differing in the height-to-span ratio were considered. For the shallow structure, a significant change in the value of the stiffness matrix determinant and the current stiffness parameter was observed. A similar tendency in the behavior of the structure can be observed on fragments of larger structures, including shallow single-layer steel domes. These problems are described on the basis of the dome, which is located on top of the building housing the restaurant. This structure is subjected to large displacement gradients and the actual configuration is taken into account in analysis. The analysis showed that there is a change in stiffness for these structures, and, therefore, that such structures should be designed according to geometric nonlinear analysis (GNA).

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Liu, Shuqiang, Jinming Dai, Husheng Jia, Xuguang Liu e Bingshe Xu. "Effect of sirospun spinning with a press bar top pin on qualities of flax/cotton blended yarn". Textile Research Journal 82, n. 10 (8 novembre 2011): 985–93. http://dx.doi.org/10.1177/0040517511427972.

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Tyschenko, Ida E., K. S. Zhuravlev, A. G. Cherkov, Andrzej Misiuk e V. P. Popov. "Сavity Effect in Hydrogen Ion Implanted Silicon-On-Insulator Structures". Solid State Phenomena 108-109 (dicembre 2005): 477–82. http://dx.doi.org/10.4028/www.scientific.net/ssp.108-109.477.

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Cavity effect on the room-temperature (RT) photoluminescence (PL) from emitting centers in the top silicon layer of silicon-on-insulator (SOI) structure has been studied. The lightemitting centers were produced by the implantation of H+ ions and subsequent annealing at the temperatures Ta = 450-1000 oC for 5 h in an Ar ambient under pressure P = 1 - 1.2×104 bar. It has been obtained that annealing under hydrostatic pressure higher than 6 kbar prevented the outdiffusion of hydrogen in the form of gas bubbles, which took place after annealing at Ta≥600 oC under atmospheric conditions. Absence of micro-pores and gas bubbles in the top surface region creates the conditions to retain the mirror quality of the SOI/air interface. A wavelength-selective effect of the formed cavity on visible PL has been observed from the H+ ion implanted SOI structures annealed under pressure of 12 kbar. The cavity enhancement of PL emission for 23-40 times has been found at the wavelength of 515 and 560 nm.

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Zhang, Rui Jin. "Effect of Steel-Concrete Interface on Reinforcement Corrosion in Marine Environment". Advanced Materials Research 250-253 (maggio 2011): 1311–14. http://dx.doi.org/10.4028/www.scientific.net/amr.250-253.1311.

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This paper dealt with the influence of the steel-concrete interface quality and environmental conditions on reinforcement corrosion. High size concrete members were cast to get different interface quality decreased with the height of rebar due to the top-bar effect. Five groups of specimen with two concrete covers have subjected to different exposed programs. The experimental results showed that the concrete cover significantly influenced corrosion initiation and corrosion rate by blocking the penetration of aggressive agents. The height of rebar affected the corrosion initiation because of the variation of concrete porosity, interface defects and chloride threshold. The existence of defects at the interface was more important than the size of defect for corrosion initiation.

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Xie, Wen Ping, Dong Zhou Xia e Wei Jun Yang. "Finite Element Analysis of Wind Vibration Control Effect for Single Transmission Tower". Applied Mechanics and Materials 670-671 (ottobre 2014): 1116–20. http://dx.doi.org/10.4028/www.scientific.net/amm.670-671.1116.

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Three-dimensional finite element analysis model of transmission tower is established by using ANSYS software. According to the characteristics of the tower, wind vibration control effect of transmission tower is to be studied through seven different kinds of distribution of MR dampers condition, then get the dynamic response in different position of the tower body and tower top. The analysis results show that:: Through using of different damper layout, it can reduce vibration of the tower, especially the third scheme which is tower head lower half part edge member bar plus dampers had the most significant vibration reduction effect. Research results can be reference for engineering design and engineering practice, it also has a certain theoretical and practical significance.

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Mamang, Fathani Adhitya, Bachtiar Bachtiar, Imam Khoirul Rohmat e Adri Fato. "ANALISIS PENGARUH VARIASI TEKANAN GAS DAN PERSENTASE KETEBALAN LAPISAN BOUNDING DAN COATING PADA PROSES REBUILD-UP MATERIAL BAJA AISI 1045 DENGAN METODE ARC SPRAY TERHADAP TINGKAT KEREKATAN ANTAR LAPISAN". JTT (Jurnal Teknologi Terapan) 9, n. 2 (31 ottobre 2023): 167. http://dx.doi.org/10.31884/jtt.v9i2.463.

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Each engine component has the durability that can decrease and wear due to continuous friction. The thermal spray method is an alternative that is used. The type of thermal spray that is found in the industry is Arc Spray. However, the peeling of the coating metal with the substrate is one of the problems. In this study, the variables that have contributed to the peeling of the coating layer were taken. The variables compared are the total thickness of the bounding and coating layers of 1 mm with a percentage of 50% : 50% and 30% : 70%. Another variation is gas pressure of 2 Bar, 3 Bar and 4 Bar in rebuild-up process of AISI 1045. Specimens with thickness percentage of 30% : 70% have significant difference in tensile strength value compared to the thickness percentage of 50% : 50% with an average difference of 5.02 MPa; 4.8975 MPa and 3.29 MPa in specimens with a gas pressure of 2 bar; 3 bars; 4 bars. The influences of thickness of bound and top coat have percentage effect 21.12% on each layer. As the gas pressure increases, the bonding value is higher because the higher gas, the smaller porosity which is proved by microstructural tests.

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Weber, Marius, Francesco Arena, Andreas Konrad e Rolf Hempelmann. "Effect of Moisture on Methane Permeation Through Fermenter Covering Films in Biogas Plants". Zeitschrift für Physikalische Chemie 232, n. 5-6 (24 maggio 2018): 603–14. http://dx.doi.org/10.1515/zpch-2017-1022.

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Abstract Methane permeation through polyamide and polyethylene mono and multilayer films has been measured via direct coupling of a gaschromatograph with a permeation measurement cell. Methane permeabilities [in cm3 (STP)·mm·d−1·bar−1·m−2] for single films were found to be 335 for polyethylene (PE) at 40°C, 0.64 for polyamide (PA) 6/6.6 with dry gas and 8.7 for PA 6/6.6 with water vapour saturated test gas. As a result, under operating conditions of biogas production facilities (40°C, water vapour saturated), the replacement of PE by PA, as biogas membrane on top of a fermenter, can reduce methane emission through permeation by a factor of about 40.

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Liu, Peng Tao, Xue Si Liu e Jin Gang Liu. "Effect of Calendering Conditions on the Properties of Paper". Advanced Materials Research 750-752 (agosto 2013): 2040–43. http://dx.doi.org/10.4028/www.scientific.net/amr.750-752.2040.

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The effect of calendering temperature, speed and linear load on the properties of opacity, brightness, smoothness, paper thickness, gloss and ink absorption of art paper were studied by orthogonal experiment. The art paper coating formulations were as follows: GCC-60 100 pph, solid content 64.6% for precoating; GCC-95 40 pph, Kaolin 60 pph, and solid content 61.3% for top coating. Bar coater was involved to coat by hand in the lab and the coating weight was controlled at 20±2g/m2. After calendering in different conditions, the optical properties and printability of paper were analyzed. Regression analysis was used to study which of the calendering conditions was the dominant factor influencing the paper properties. The results showed that linear load was the dominant one, followed by the calendering temperature and calendering speed. After calendering, smoothness and gloss increased, while the brightness and opacity decreased.

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Zhang, Ruijin, Arnaud Castel e Raoul François. "Influence of steel–concrete interface defects owing to the top-bar effect on the chloride-induced corrosion of reinforcement". Magazine of Concrete Research 63, n. 10 (ottobre 2011): 773–81. http://dx.doi.org/10.1680/macr.2011.63.10.773.

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Hasnain, Muhammad, e Farheen. "Error Analysis in English Writing at Matric Level in the Secondary Schools of Tehsil Rustam". journal of social sciences review 2, n. 2 (30 giugno 2022): 10–21. http://dx.doi.org/10.54183/jssr.v2i2.33.

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The students at Matric level commit certain errors in English writing. This research was conducted to find out the errors committed by the metric students at Tehsil Rustam. A total of 60 students – top 20 students were selected from the top three schools of Tehsil Rustam. They were given the task to write on three topics namely “My school”, “My best friend” and “My favourite teacher”. To analyze the errors of the students, the researcher applied “Darus et al model of Error analysis theory”. The errors of the students were categorized and put into bar charts and pie charts. The researcher noted that the errors committed by these students are partly due to the effect of first language (L1) on second language (L2) and partly due to word by word translation either from the mother tongue (Pashto) or the national language (Urdu) to English.

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Dybeł, Piotr, Daniel Wałach e Krzysztof Ostrowski. "The Top-Bar Effect in Specimens with a Single Casting Point at One Edge in High-Performance Self-Compacting Concrete". Journal of Advanced Concrete Technology 16, n. 7 (13 luglio 2018): 282–92. http://dx.doi.org/10.3151/jact.16.282.

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Zhang, R., A. Castel e R. François. "Concrete cracking due to chloride-induced reinforcement corrosion – influence of steel–concrete interface defects due to the ‘top-bar effect’". European Journal of Environmental and Civil Engineering 16, n. 3-4 (aprile 2012): 402–13. http://dx.doi.org/10.1080/19648189.2012.667984.

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Pujol, M. C., R. Solé, J. Massons, Jna Gavaldà, X. Solans, C. Zaldo, F. Díaz e M. Aguiló. "Structural study of monoclinic KGd(WO4)2and effects of lanthanide substitution". Journal of Applied Crystallography 34, n. 1 (1 febbraio 2001): 1–6. http://dx.doi.org/10.1107/s0021889800013352.

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The crystal structure of monoclinic KGd(WO4)2(KGW) has been refined at room temperature by using single-crystal X-ray diffraction data. The unit-cell parameters area= 10.652 (4),b= 10.374 (6),c= 7.582 (2) Å, β = 130.80 (2)°, withZ= 4, in space groupC2/c. The linear thermal expansion tensor has been determined and the principal axes are [302], [010] and [106]. The principal axis with maximum thermal expansion (\boldalpha'_{33} = 23.44 × 10−6 K−1), {\bf X}'_{3}, was located 12° from thecaxis. Undoped crystals of KGW and crystals that were partially doped by Pr, Nd, Ho, Er, Tm and Yb were grown by the top-seeding-solution growth slow-cooling method. The effect of doping on the KGW structure was observed in the cell parameters and in morphological changes. The changes in parameters follow the changes in lanthanide ionic radii. The doped crystals show {021} and {\bar{2}21} faces in addition to the {110}, {\bar{1}11}, {010}, {130} and {310} faces which basically follow the habit of the undoped KGW crystals. The development of the faces is related to the number of the most important periodic bond chains parallel to them.

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Dybeł, Piotr. "Effect of casting direction on bond of reinforcement in High Performance Self-Compacting Concrete (HPSCC)". MATEC Web of Conferences 262 (2019): 06004. http://dx.doi.org/10.1051/matecconf/201926206004.

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This paper presents the results of an investigation into the steel-to-concrete bond in high-performance self-compacting concrete (HPSCC) based on direct pull-out tests. Specifically, the effect of the casting direction on bond properties is examined. Two variants of concrete mixture casting were considered in this work: from the top and from the bottom of a mould with a single casting point at one edge. Horizontal specimens with transverse rebars distributed over their heights (480 mm) and lengths (1600 mm) were cast. The experimental program has shown that the direction of concreting plays an important role in the formation of the bond condition. In the case of casting a mixture from the bottom of a mould, in the lower part of a specimen there is no significant change of the bond stress. However, there is a strong improvement in the upper part. The phenomenon observed eliminates the top-bar effect. What is more, for the rebars situated in the upper part of a specimen, improvements in bond characteristics, such as the bond stiffness, bond strength and the effect of the rebar distance from the casting point are all observed in the case of casting a mixture from the bottom of a mould.

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Wang, Tao, Enrique Serra Bachs, Joris de Grooth e Wiebe M. de Vos. "Advanced Oxidation Processes Coupled to Nanofiltration Membranes with Catalytic Fe0 Nanoparticles in Symmetric and Asymmetric Polyelectrolyte Multilayers". Membranes 13, n. 4 (28 marzo 2023): 388. http://dx.doi.org/10.3390/membranes13040388.

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The in situ synthesis of Fe0 particles using poly-(acrylic acid) (PAA) is an effective tool for fabricating catalytic membranes relevant to advanced oxidation processes (AOPs). Through their synthesis in polyelectrolyte multilayer-based nanofiltration membranes, it becomes possible to reject and degrade organic micropollutants simultaneously. In this work, we compare two approaches, where Fe0 nanoparticles are synthesized in or on symmetric multilayers and asymmetric multilayers. For the membrane with symmetric multilayers (4.0 bilayers of poly (diallyldimethylammonium chloride) (PDADMAC)/PAA), the in situ synthesized Fe0 increased its permeability from 1.77 L/m2/h/bar to 17.67 L/m2/h/bar when three Fe2+ binding/reducing cycles were conducted. Likely, the low chemical stability of this polyelectrolyte multilayer allows it to become damaged through the relatively harsh synthesis. However, when the in situ synthesis of Fe0 was performed on top of asymmetric multilayers, which consist of 7.0 bilayers of the very chemically stable combination of PDADMAC and poly(styrene sulfonate) (PSS), coated with PDADMAC/PAA multilayers, the negative effect of the Fe0 in situ synthesized can be mitigated, and the permeability only increased from 1.96 L/m2/h/bar to 2.38 L/m2/h/bar with three Fe2+ binding/reducing cycles. The obtained membranes with asymmetric polyelectrolyte multilayers exhibited an excellent naproxen treatment efficiency, with over 80% naproxen rejection on the permeate side and 25% naproxen removal on the feed solution side after 1 h. This work demonstrates the potential of especially asymmetric polyelectrolyte multilayers to be effectively combined with AOPs for the treatment of micropollutants (MPs).

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Shi, Zheng, Long Wei Qiu e Yong Qiang Yang. "Study on Sedimentary Characteristics and Models of River Group Sequence". Applied Mechanics and Materials 608-609 (ottobre 2014): 1141–46. http://dx.doi.org/10.4028/www.scientific.net/amm.608-609.1141.

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Zhunzhong area Qingshui River group has top and bottom boundaries,which are not clear,and research on the evolution of the lack in sequence stratigraphic framework of deposition and on the reservoir sand body types do not have a clear understanding problem.In seismic interpretation, core description and based on the analysis of the related test,combining with the mud logging and well logging data,for the redefinition of Qingshui River group on the top and bottom boundaries,it identifies 6 time significance of sequence boundary,taking Qingshui River group can be divided into 2 sequences, 5 system tracts;clear and definite the study area mainly developed delta lacustrine depositional system,which can be further divided into the delta front subfacies, beach bar facies and semi deep lake subfacies. It takes an analysis on the sedimentary characteristics and distribution rules of different types, and it controls effect of topography and hydrodynamic conditions on deposition system, and then puts forward the corresponding sedimentary patterns.

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Oun, Dahfer Ali, e Alaa Subr. "Effect of Vertical Boom Position of the Greenhouse Sprayer on the Penetration of Spray to the Eggplants Canopy". IOP Conference Series: Earth and Environmental Science 1262, n. 9 (1 dicembre 2023): 092009. http://dx.doi.org/10.1088/1755-1315/1262/9/092009.

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Abstract The research objective focuses on spraying the leaves of the plant from the top and bottom through a spraying machine designed and made of aluminum with a movable arm equipped with a nozzle holder divided into three parts and each piece contains a nozzle of the type (Flat Fan 120-C3) as the machine was tried in a greenhouse with a study of the effect of changing the positions of the upper and lower piece of the tube carrying the nozzles to four levels (A1, A2, A3, A4) and the effect of pressure change on two levels (2,4) bar and studying the effect of the previous factors on some of the characteristics of the study, Spray quality on adaxial of leaf, Spray quality on the abaxial surface of a leaf, spraying on all test sheets placed on the eggplant plant. The experimental design is RCBD according to the SPLIT-PLOT system and for three repeaters using the least significant difference (LSD) with a probability level of 0.05. The results showed that the A2 situation was significantly superior to all the studied qualities, and the pressure (4 bar) was significantly superior to all the studied qualities. As for the interaction position of boom (A4) with the pressure of (4bars), its result in all qualities was less than the rest of the coefficients, and it is not significant at the level of (0.05).

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31

Trezos, Konstantinos G., Ioannis P. Sfikas e Christos Gerasimos Pasios. "Influence of water-to-binder ratio on top-bar effect and on bond variation across length in Self-Compacting Concrete specimens". Cement and Concrete Composites 48 (aprile 2014): 127–39. http://dx.doi.org/10.1016/j.cemconcomp.2013.11.012.

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32

Maurya, Preeti, Gaddale Srinivas Vijay e Raghavendra Cholpadi Kamath. "Investigation on Performance and Kerf Characteristics during Cryogenic-Assisted Suspension-Type Abrasive Water Jet Machining of Acrylonitrile Butadiene Rubber". Journal of Composites Science 6, n. 12 (19 dicembre 2022): 397. http://dx.doi.org/10.3390/jcs6120397.

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Abstract (sommario):

The need for soft polymer (such as acrylonitrile butadiene rubber (ABR)) components in mating applications is increasing in several sectors, viz. automobile, mining, and marine, due to their viscoelastic nature with improved surface quality and tighter geometric tolerances. Therefore, this paper aims to compare the effect of cryogenic conditions on the performance parameters of the suspension-type abrasive water jet (S-AWJ) machining and investigate the kerf characteristics of the top and bottom surface by comparing the waviness of the cut profiles and abrasive contamination of the top surface near the vicinity of the slot under conventional (room temperature) and cryogenic (liquid nitrogen (LN2)) conditions. The study found that the use of LN2 positively affected the performance parameters (Kerf taper ratio (KTR) and material removal rate (MRR)) due to a sudden increase in Young’s modulus and a decrease in elasticity of the machining zone. The cryogenic-assisted S-AWJ at the highest water jet pressure (WJP) (250 bar) produced better kerf characteristics through uniform and waviness-free top and bottom kerf profiles than the other experimental sequences. The use of LN2 resulted in the embrittlement of ABR, due to which less garnet abrasive particle contamination was observed during cryogenic-assisted S-AWJ machining.

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33

Li, Yanfeng, Jiyuan Xie, Fengchi Wang, Di Wu, Jiahui Wang e Yanao Liu. "Experimental Study on Shear Lag Effect of Long-Span Wide Prestressed Concrete Cable-Stayed Bridge Box Girder under Eccentric Load". Construction Materials 4, n. 2 (20 maggio 2024): 425–43. http://dx.doi.org/10.3390/constrmater4020023.

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Abstract (sommario):

Based on the engineering background of the wide-width single cable-stayed bridge, the shear lag effects of the cross-section of these bridge box girders under the action of the eccentric load were experimentally studied. The behavior of shear lag effects in the horizontal and longitudinal bridge directions under eccentric load in the operational stage of a single cable-stayed bridge was analyzed by a model testing method and a finite element (FE) analytical method. The results showed that the plane stress calculation under unidirectional live load was similar to the results from spatial FE analysis and structural calculations performed according to the effective flange width described in the design specification. At the position of the main beam near the cable force point of action, the positive stress at its upper wing edge was greatest. At a distance from the cable tension point, the maximum positive stress position trend showed that from the center of the top flange to the junction of the top flange and the middle web to the junction of the top flange and the middle web and the side web. Under eccentric load, the positive and negative shear lag effects on the end fulcrum existed at the same time, and the shear lag coefficient on the web plate was larger than the shear lag coefficient on the unforced side. Due to the influence of constraint at the middle fulcrum near the middle pivot point, positive and negative shear lag effects were significant, and the coefficient variation range was large, resulting in large tensile stress on the roof plate in this area. According to FE analytical results, stress and shear forces of a single box three-chamber box girder under eccentric load were theoretically analyzed, the bending load decomposed into the accumulation of bending moment and axial force, using the bar simulation method, and the overall shear lag effect coefficient λ was obtained and verified.

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34

Ibraheem, Sajad Nazim, e Majed Hazem Alheidary. "The Role of Spray Pattern and Operating Pressure and their Interactions on the Control of Tetranychus urticae Koch. in Eggplant Plants Under Greenhouse Conditions". Arab Journal for Plant Protection 41, n. 2 (2023): 105–13. http://dx.doi.org/10.22268/ajpp-41.2.105113.

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Abstract (sommario):

Ibraheem, S.N. and M.H. Alheidary. 2023. The Role of Spray Pattern and Operating Pressure and their Interactions on the Control of Tetranychus urticae Koch. in Eggplant Plants Under Greenhouse Conditions. Arab Journal of Plant Protection, 41(2): 105-113. https://doi.org/10.22268/AJPP-41.2.105113 The mite Tetranychus urticae Koch is one of the most dangerous pests that attack the eggplant (Solanum melongena L.). Several attempts were carried out for controlling this pest to avoid crop losses through the extensive use of chemical products. The present study aimed to shed light on the effect of spraying pattern used coupled with selecting the appropriate operating pressure to obtain a suitable droplet size and density deposited on the leaves to get optimal effect for the control of mites which attack eggplant under greenhouse conditions. Six types of spray patterns (from top, side, bottom, top and side together, bottom and side together, and combination spray mode) toward plant canopy and two different operating pressures (2 and 5 bar) were tested. The factorial experiment was applied in split-plot arrangement in a complete random design. The significant differences between the parameters studied were tested by calculating the least significant difference (L.S.D.) at P=0.05. The findings showed a clear significant influence in the control efficiency by both spraying patterns and operating pressures. Significant mortality efficiency was observed using the bottom spray pattern from the plant canopy especially at 5 bar constant pressure in comparison with the other spray patterns at the same operating pressure. It was also observed that spraying with two-nozzle spray pattern from the bottom led to an increase in the efficiency of killing mites not only on the bottom part of the plant but also those present in the upper part of the plant, with a morality rate of 22.67% compared to the control treatment. The results also illustrated that the use of bottom spray pattern reduced the amount of pesticide applied by more than 46% in comparison to the other treatments. Keywords: sprayer, nozzle, pesticide, spray process characteristics, pest control, morality efficiency

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35

Foroughi, A., J. Gherekhloo e F. Ghaderi-Far. "Effect of plant density and seed position on mother plant on physiological characteristic of cocklebur (Xanthium strumarium) seeds". Planta Daninha 32, n. 1 (marzo 2014): 61–68. http://dx.doi.org/10.1590/s0100-83582014000100007.

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Abstract (sommario):

Experiments were conducted in 2010 to determine the influence of plant density and seed position on the mother plant on seed physiological characteristics of cocklebur (Xanthium strumarium). Cocklebur burs were collected in fall of 2010 from Research Farm of University of Agricultural Sciences and Natural Resources of Gorgan, Iran. The experiment was established as factorial arrangement using a completely randomized design with three replications. The factors included different densities of cocklebur (0, 2, 4, 6 and 8 plant m-2) and the top and bottom parts of the canopy. Non dormant seeds were used for determining cardinal temperatures and tolerance to salinity and drought stresses. Base, optimum and ceiling germination temperatures were estimated between 7.09 to 12.33, 32 to 35 and 44 to 45 respectively in different treatments. Salinity stress up to 300 Mm and osmotic potential 8 bar inhibited the germination completely. Comparison of base temperatures and sigmoid equation coefficients showed that seeds produced in the top had higher germination than those that produced at the bottom of the mother plant. It seems plant densities through seed position on the mother plant affect seed quality. Likewise changes of light quality and quantity in shade environment increased seed dormancy in matured seeds. Shade environment affect seed germination on mother plant that increased dormancy of seeds maturing under shade be an adaptive response that reduces the probability of germination of offspring under unfavorable (shade, competitive) conditions.

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36

El-Anwar, Mohamed, Rami Ghali e Mona Aboelnagga. "3D Finite Element Study on: Bar Splinted Implants Supporting Partial Denture in the Reconstructed Mandible". Open Access Macedonian Journal of Medical Sciences 4, n. 1 (9 febbraio 2016): 164–71. http://dx.doi.org/10.3889/oamjms.2016.027.

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AIM: This study aimed to estimate the stress patterns induced by the masticatory loads on a removable prosthesis supported and retained by bar splinted implants placed in the reconstructed mandible with two different clip materials and without clip, in the fibula-jaw bone and prosthesis using finite element analysis.METHODS: Two 3D finite element models were constructed, that models components were modeled on commercial CAD/CAM software then assembled into finite element package. Vertical loads were applied simulating the masticatory forces unilaterally in the resected site and bilaterally in the central fossa of the lower first molar as 100N (tension and compression). Analysis was based on the assumption full osseointegration between different types of bones, and between implants and fibula while fixing the top surface of the TMJ in place.RESULTS: The metallic bar connecting the three implants is insensitive to the clips material. Its supporting implants showed typical behavior with maximum stress values at the neck region. Fibula and jaw bone showed stresses within physiologic, while clips material effect seems to be very small due to its relatively small size.CONCLUSION: Switching loading force direction from tensile to compression did-not change the stresses and deformations distribution, but reversed their sign from positive to negative.

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Razi, F., A. Azwar, S. Sofyana, N. M. Erfiza e M. Luxyana. "Preparation and characterization of nanofiltration (NF) polyethersulfone and its preliminary studies on beta-carotene concentration from crude palm oil". IOP Conference Series: Earth and Environmental Science 1116, n. 1 (1 dicembre 2022): 012064. http://dx.doi.org/10.1088/1755-1315/1116/1/012064.

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Abstract The enrichment of beta-carotene concentration from crude palm oil (CPO) using nanofiltration polyethersulfone (NF-PES) membrane was studied. This work begins with preparing the NF-PES membrane via the phase inversion method as the first stage. PES polymer was used as base membrane material and N-Methyl-2-Pyrrolidone (NMP) as a solvent. Then, the process concentration of beta-carotene was conducted by filtration of the red palm methyl ester as feed solution using dead-end mode filtration. The objective of this work was to evaluate the effect of separation pressure (3; 4; and 5 bar) on beta-carotene concentration from the feed solution. SEM results showed that the NF PES membrane had an asymmetric structure. It consisted of two layers: the thin top layer had a dense structure, while the support layer had a sponge-like structure. Besides, the pure water permeability of NF PES membrane was about 2-18 L/m2.h.bar was fitted within the range of NF membranes. The optimum operating pressure that gives the highest beta-carotene concentration was achieved at 3 bar. As a result, the beta-carotene concentration has improved about 1.14 times compared to the initial beta-carotene concentration in the feed solution.

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38

Rajesh, T. N., T. J. S. Jothi e T. Jayachandran. "Preliminary Studies on Non-Reactive Flow Vortex Cooling". Recent Patents on Mechanical Engineering 12, n. 3 (26 settembre 2019): 262–71. http://dx.doi.org/10.2174/2212797612666190510115403.

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Abstract (sommario):

Background: The impulse for the propulsion of a rocket engine is obtained from the combustion of propellant mixture inside the combustion chamber and as the plume exhausts through a convergent- divergent nozzle. At stoichiometric ratio, the temperature inside the combustion chamber can be as high as 3500K. Thus, effective cooling of the thrust chamber becomes an essential criterion while designing a rocket engine. Objective: A new cooling method of thrust chambers was introduced by Chiaverni, which is termed as Vortex Combustion Cold-Wall Chamber (VCCW). The patent works on cyclone separators and confined vortex flow mechanism for providing high propellant mixing with improved degree of turbulence inside the combustion chamber, providing the required notion for studies on VCCW. The flow inside a VCCW has a complex structure characterised by axial pressure losses, swirl velocities, centrifugal force, flow reversal and strong turbulence. In order to study the flow phenomenon, both the experimental and numerical investigations are carried out. Methods: In this study, non-reactive flow analysis was conducted with real propellants like gaseous oxygen and hydrogen. The test was conducted to analyse the influence of mixture ratio and injection pressure of the propellants on the chamber pressure in a vortex combustion chamber. A vortex combustor was designed in which the oxidiser injected tangentially at the aft end near the nozzle spiraled up to the top plate and formed an inner core inside the chamber. The fuel was injected radially from injectors provided near the top plate and the propellants were mixed in the inner core. This resulted in enhanced mixing and increased residence time for the fuel. More information on the flow behaviour has been obtained by numerical analysis in Fluent. The test also investigated the sensitivity of the tangential injection pressure on the chamber pressure development. Results: All the test cases showed an increase in chamber pressure with the mixture ratio and injection pressure of the propellants. The maximum chamber pressure was found to be 3.8 bar at PC1 and 2.7 bar at PC2 when oxidiser to fuel ratio was 6.87. There was a reduction in chamber pressure of 1.1 bar and 0.7 bar at PC1 and PC2, respectively, in both the cases when hydrogen was injected. A small variation in the pressure of the propellant injected tangentially made a pronounced effect on the chamber pressure and hence vortex combustion chamber was found to be very sensitive to the tangential injection pressure. Conclusion: VCCW mechanism has been to be found to be very effective for keeping the chamber surface within the permissible limit and also reducing the payload of the space vehicle.

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Arnott, R. W. C. (Bill), Mike Tilston, Patricia Fraino, Lillian Navarro, Gerry Dumouchel e Nicole Miklovich. "Laterally accreting sinuous channels and their deposits: The Goldilocks of deep-water slope systems". Journal of Sedimentary Research 91, n. 5 (14 maggio 2021): 451–63. http://dx.doi.org/10.2110/jsr.2020.144.

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ABSTRACT Channels with a sinuous planform are common in both continental and deep-marine environments on Earth, and similarly in high-resolution images of the surface of Mars. Whereas common in rivers, continuous lateral channel migration and point-bar deposition appear to be much less common in the deep sea. In the bends of rivers, near-bed flow driving point bar growth results from a cross-flow superelevation of the water surface that sets up a lateral hydrostatic pressure gradient driving an inward-directed flow near the bed. However, in deep-marine systems the surface between the turbidity current and overlying ambient fluid sits well above the channel margins, and therefore precludes a similar lateral superelevation of the current top. Here it is argued that the cross-flow component is related to a density gradient that mimics the effect of the hydrostatic pressure gradient in rivers, and develops as coarse suspended particles that experience little uplift, and therefore negligible overspill, become concentrated along the outer bank. This condition develops best in a two-part suspension made up of a highly concentrated, unstratified basal plug of coarse sediment overlain sharply by a dilute cloud of much finer sediment—a density structure that differs from the more typical upward exponential decrease in density. The abundance of coarse and fine sand, but depletion in the intermediate grain size fraction, is related to transgressive shelf processes and its influence on sediment supplied to the system, and in turn, the flow structure of the current. It is under these seemingly uncommon granulometric conditions that continuous laterally migrating channels, and accordingly, riverine-like point-bar deposition, is most common in the deep sea.

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Nakahara, Yusuke. "Concealed Fragmentariness: On the Compositional Process of Bartók's String Quartets". Studia Musicologica 62, n. 3-4 (28 giugno 2022): 241–76. http://dx.doi.org/10.1556/6.2021.00017.

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Abstract The present paper is a preliminary study to a deeper understanding of Bartók's compositional process: how he filled the music paper even if the notation appears continuous. He did not always write the draft from the top-left corner to the bottom-right corner but occasionally skipped some measures or phrases that he intended to write down later. Thus, the continuity draft is not necessarily regarded as a continuity; it might have consisted of fragments but they have been eventually concealed in the final form of the draft. This may directly affect our interpretation of Bartók's creative process. The present research takes the visual appearance of a draft as a clue to examine its hypothetical fragmentariness. Beginning with the examination of some actual blank spaces that were never filled, the paper deals with cases where the original existence of fragments is suggested by the extraordinary appearance of the draft, such as a blank space at the end of a system, notations in the margin, re-organization of bar-lines, etc. Besides systematic approaches to fragmentariness, the author offers some interpretation concerning the reasons why Bartók did not write the draft in an ordinary way. There might have been different explanations for the interruption of the linear compositional process. One of the important findings of this paper is that Bartók's bar-lines do not always mark metric accents but sometimes simply facilitate the performers' orientation. Even though the occasional special function of some of his bar-lines as mere markers of orientation is explained by Bartók in a letter to Rudolf Kolisch, the existence of philological evidence to this effect may further underline its validity and importance.

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Mezzatesta, Daniela S., Federico J. Berli, Celeste Arancibia, Fernando G. Buscema e Patricia N. Piccoli. "Impact of contrasting soils in a high-altitude vineyard of <i>Vitis vinifera</i> L. cv. Malbec: root morphology and distribution, vegetative and reproductive expressions, and berry skin phenolics". OENO One 56, n. 2 (30 maggio 2022): 149–63. http://dx.doi.org/10.20870/oeno-one.2022.56.2.4917.

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Abstract (sommario):

The high-altitude viticulture of Mendoza is being increasingly recognised among the top wine regions worldwide. High levels of solar ultraviolet-B (UV-B) radiation, alluvial heterogeneous soils and cool night temperatures are major influences on Vitis vinifera L. phenotypic characteristics, especially on Malbec, Argentina’s emblematic grapevine variety. In the present work, the effect of intra-vineyard contrasting soil depth on Malbec was evaluated in a high-altitude vineyard (1450 m a.s.l.), over two growing seasons for physiological traits and over three vintages for yield components and berry skin phenolic compounds. The experiment was carried out in two parcels of shallow (SS) and deep (DS) soils, with different physico-chemical characteristics, and submitted to equal irrigation and crop management. Results showed that root depth was not limited by any soil physical constraints and fine roots (< 1 mm) were patchily distributed in sites with higher contents of silt, clay and organic matter in SS. Higher root quantity in SS was related to lower vegetative and reproductive expressions, shorter ripening period and reduced berry size and fruit yield when compared to DS. When SS plants experienced mild water stress (ΨS, stem water potential, between -6 and -9 bar) increments of anthocyanins, total polyphenols and antioxidant capacity in berry skins were observed. However, when SS plants reached ΨS ≤ -10 bar, physiological harm occurred. The results presented contribute to understanding the effects of soil type on Malbec vines during different seasonal environmental conditions, especially in stressful situations, such as those expected by climate change scenarios.

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Trezos, Konstantinos G., Ioannis P. Sfikas e Konstantinos Orfanopoulos. "Bond of self-compacting concrete incorporating silica fume: Top-bar effect, effects of rebar distance from casting point and of rebar-to-concrete relative displacements during setting". Construction and Building Materials 73 (dicembre 2014): 378–90. http://dx.doi.org/10.1016/j.conbuildmat.2014.09.113.

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Roohnia, Mehran, Seyed-Fariborz Hashemi-dizaji, Loïc Brancheriau, Ajang Tajdini, Amir-Hooman Hemmasi e Negin Manouchehri. "Effect of soaking process in water on the acoustical quality of wood for traditional musical instruments". BioResources 6, n. 2 (23 aprile 2011): 2055–65. http://dx.doi.org/10.15376/biores.6.2.2055-2065.

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Abstract (sommario):

The damping coefficient of the first mode in the longitudinal vibration of mulberry and walnut woods was characterized to find justifications for the water soaking of woods in traditional musical instrument industries in Iran. Visually clear and sound beams were prepared from Morus alba and Juglans regia, and the damping coefficient in the temporal field was evaluated before and after three continuous cycles of soaking of specimens in distilled water (24 hours, pH 7, and temperature 50 oC). Experiments were conducted with free longitudinal vibration using the free-free bar method in 360 × 20 × 20 (L ×R ×T) dimensions. Soaking cycles homogenized and decreased the damping coefficient in both species. On the basis of such results, the suitability of water soaked specimens is discussed in traditional musical instrument industries in Iran, taking into the account the longitudinal sound velocity, modulus of elasticity, and density affecting the acoustic limits. These two series of testing specimens were suitable in resonators and xylophone bars for backs, sides, and ribs and not for top plates, unless as the outstanding piece, since they marginally meet the density, sound velocity and damping coefficient limits qualified for those applications.

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Shete, H. V., e M. S. Sohani. "Effect of Process Parameters on Surface Roughness in HPC Drilling of AISI 1055 Steel". Journal of Mechanical Engineering 17, n. 1 (1 aprile 2020): 33–48. http://dx.doi.org/10.24191/jmeche.v17i1.15217.

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Abstract (sommario):

Data regarding the influence of high-pressure coolant on the performance of drilling process using design of experiment has been limitedly available. This paper presents the effect of higher coolant pressures along with spindle speed, feed rate and peck depth on the surface roughness of hole using Taguchi technique. Experimental set up was developed consisting of specially manufactured high-pressure coolant system and high-pressure adapter assembly attached to vertical machining center. Developed experimental set up has optimized utilization of non-through coolant vertical machining center in a small-scale industry. Experiments were conducted on AISI 1055 steel with TiAIN coated drill on the vertical machining center. Taguchi technique was used for design of experiment and analysis of results. Results revealed that the surface roughness improve till coolant pressure reaches to an optimum value of 13.5 bar and there after it decreases. Coolant pressure and spindle speed was the significant process parameters for the hole surface roughness. Surface roughness at the top of hole was considerably lower than the bottom of hole, under the action of all process parameters. Supply of coolant at high pressure has resulted in lower surface roughness even with large peck depth; which indicate that, manufacturing cost can be reduced with the use of high-pressure coolant in drilling.

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Li, Shuwei, Wen Zhao e Zhiyu Guo. "Seismic Response Analysis of Silo-Stock-Foundation Interaction System". Frontiers Research of Architecture and Engineering 1, n. 2 (28 aprile 2018): 43. http://dx.doi.org/10.30564/frae.v1i2.46.

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Abstract (sommario):

To analyze the response law of silo-stock-foundation interaction system under seismic load, a dynamic equation of this interaction system was established. Furthermore, the dynamic characteristics of the silo-stock- oundation interaction system under different storage conditions were studied through numerical analysis. The displacement at the silo top was much greater than that at the silo bottom, while the vibration trend of the upper and lower silos on the same bus bar was similar. The acceleration response, displacement and stress response of the structure increased with the increase of the input seismic wave. Furthermore, the direction time responses of several typical silo parts were consistent. With increase in storage material, the acceleration peak of the silo and bulk material increased and then decreased. This indicates that the relative motion of the storage material and silo had a damping effect on the silo system. The maximum circumferential strain and equivalent stress of silos with different storage capacities were recorded at the variable section of silos (the top of funnel). The effective stress beneath foundations near silos was obviously higher than that far away from silos. These results can provide a reliable theoretical basis and reference values for mitigating silo structural failures under seismic load.

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Zhang, Jindan, Junlin Chen, Xiaogang Ye, Xiuli Qiu, Lijiao Deng e Ying Su. "Experimental Study on Flexural Behavior of the Composite Bottom Slab of the Stiffened Steel Truss". Journal of Physics: Conference Series 2519, n. 1 (1 giugno 2023): 012030. http://dx.doi.org/10.1088/1742-6596/2519/1/012030.

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Abstract In order to study the influence of rib size on the flexural performance of the new reinforced truss concrete composite floor slab, two precast reinforced concrete floor slabs and one ordinary reinforced truss composite floor slab were designed and manufactured for flexural performance tests. The failure mode of the concrete slab under uniform load was analyzed, and the influence of rib size on the flexural capacity of the floor slab was studied. The results show that the stiffening of the steel truss composite slab can significantly improve the stiffness of the precast slab and effectively solve the problem of excessive deflection of the precast slab during construction. On the basis of the experimental study, the influence of the top chord steel bar diameter, concrete rib height and rib width on the short-term stiffness of the floor is deeply analyzed by using the finite element refined modeling. The results show that the diameter of the top chord reinforcement and the width of the concrete rib are positively related to the stiffness of the composite slab, and the height of the concrete rib has little effect on the initial stiffness of the precast slab, which mainly plays a role in the later stage.

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Garić, Ljubiša, Dardan Klimenta, Darius Andriukaitis e Saša Jovanović. "Modeling the Effects of Horizontal Transverse Vibrations on the Thermal Behavior and the Ampacity of Rectangular Bus Bars". Applied Sciences 13, n. 11 (1 giugno 2023): 6745. http://dx.doi.org/10.3390/app13116745.

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Abstract (sommario):

The purpose of this research is to correctly model steady-state heat transfer in and around rectangular bus bars installed horizontally in an indoor environment and to estimate the corresponding ampacities, considering the effects of horizontal transverse vibrations caused by electromagnetic forces. This thermo-electro-magneto-mechanical problem is solved analytically using correlations determined experimentally by other researchers, while the accuracy of the obtained results is verified numerically using the finite element method (FEM). The novelties of the developed model are as follows. First, modeling the effects of horizontal transverse vibrations on free convection from the top and bottom surfaces of rectangular bus bars via forced convection for different characteristic lengths. Second, modeling the effects of vibration amplitudes and vibration frequencies on the bus bar ampacity. Third, introducing the existing vibration classes (A, B, and C) into the analytical and FEM-based thermal analyses. The results show that with an increase either in the vibration amplitude or the vibration frequency, there is a greater convection-based dissipation of heat from the bus bars and an increase in their ampacity. Finally, for the standard vibration classes, it is found that the effect of horizontal transverse vibrations on the ampacity can be up to 41.99% for Class C.

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Abdullah, Alaa H., e Shatha D. Mohammed. "The Fire Effect on the Performance of Reinforced Concrete Beams with Partial Replacement of Coarse Aggregates by Expanded Clay Aggregates". Engineering, Technology & Applied Science Research 13, n. 6 (5 dicembre 2023): 12220–25. http://dx.doi.org/10.48084/etasr.6412.

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This paper aims to investigate the flexural behavior of reinforced concrete beams considering fire resistance by adding Lightweight Expanded Clay Aggregates (LECA) to the concrete mix as partial coarse aggregate replacement. LECA is a type of porous clay with a uniform pore structure with fine, closed cells and hard, tightly sintered skin. The experimental work comprised four reinforced self-compacted concrete beams. All the specimens were identical in their geometrical layout of 1600×240×200 mm, reinforcement details, and support condition (simply supported). For all the beams, the main reinforcement was provided by two bars, each having a diameter of 12 mm, while a bar of 6 mm diameter was employed for the top and shear reinforcement. Each beam had a different replacement ratio of LECA for coarse aggregates (0, 10, 20, and 30%). All the specimens were tested under static two concentrated loads after being exposed to the fire of steady-state temperature (500 oC), 1 hr duration, and sudden cooling process. The results showed that adding LECA reduced the number and width of the generated cracks due to fire and reduced the deterioration of the ultimate load capacity and beam rigidity (stiffness).

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49

Valcuende, M., C. Parra e S. Balasch. "A discussion of the paper “Top-bar effect of steel bars in self-consolidating concrete (SCC)” by M. Reza Esfahani, M. Lachemi, M. Reza Kianoush". Cement and Concrete Composites 30, n. 10 (novembre 2008): 1020. http://dx.doi.org/10.1016/j.cemconcomp.2008.09.002.

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50

Elliott, S., A. A. Firsov e S. B. Leonov. "Oblique shock wave reflection at plasma array presence". Journal of Physics: Conference Series 2100, n. 1 (1 novembre 2021): 012008. http://dx.doi.org/10.1088/1742-6596/2100/1/012008.

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Abstract This work discusses the effect of a filamentary plasma array on shock wave (SW) reflection pattern and on a shock-induced separation zone geometry. It includes experimental and computational components both. The experimentation was performed in the supersonic blowdown test rig SBR-50 at the University of Notre Dame at flow Mach number M=2, stagnation pressure P0=1.7-2.7 bar and stagnation temperature T0=300 K. Oblique shock wave generator composed of a symmetric solid wedge was installed on the top wall of test section while the filamentary plasma generator was arranged on the opposite wall. Thus, the main SW originating from the wedge impinged the plasma area. As a result of the SW-plasma interaction, the flowfield was significantly modified, including a shift of the main SW upstream and redistribution of wall pressure over the test section. The computational analysis allowed a 3D reconstruction of the SW interaction with the plasma array. The physics of SW-plasma array interaction are also discussed.

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