Artículos de revistas: "BEMs rapides"

1

Zhang, Chenchu, Hanchang Ye, Rui Cao, Shengyun Ji, Heng Zhang, Linhan Zhao, Sizhu Wu y Hua Zhai. "Rapid fabrication of microrings with complex cross section using annular vortex beams". Chinese Optics Letters 20, n.º 2 (2022): 023801. http://dx.doi.org/10.3788/col202220.023801.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

2

Patterson, Thomas E., Yoshitada Sakai, Mark D. Grabiner, Michael Ibiwoye, Ronald J. Midura, Maciej Zborowski y Alan Wolfman. "Exposure of murine cells to pulsed electromagnetic fields rapidly activates the mTOR signaling pathway". Bioelectromagnetics 27, n.º 7 (2006): 535–44. http://dx.doi.org/10.1002/bem.20244.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

3

Month, Mel. "Education in a rapidly advancing technology: Accelerators and beams". American Journal of Physics 68, n.º 6 (junio de 2000): 556–70. http://dx.doi.org/10.1119/1.19484.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

4

Wu, Ke, Bruno D. Welfert y Juan M. Lopez. "Librational forcing of a rapidly rotating fluid-filled cube". Journal of Fluid Mechanics 842 (13 de marzo de 2018): 469–94. http://dx.doi.org/10.1017/jfm.2018.157.

Texto completo

Resumen

The flow response of a rapidly rotating fluid-filled cube to low-amplitude librational forcing is investigated numerically. Librational forcing is the harmonic modulation of the mean rotation rate. The rotating cube supports inertial waves which may be excited by libration frequencies less than twice the rotation frequency. The response is comprised of two main components: resonant excitation of the inviscid inertial eigenmodes of the cube, and internal shear layers whose orientation is governed by the inviscid dispersion relation. The internal shear layers are driven by the fluxes in the forced boundary layers on walls orthogonal to the rotation axis and originate at the edges where these walls meet the walls parallel to the rotation axis, and are hence called edge beams. The relative contributions to the response from these components is obscured if the mean rotation period is not small enough compared to the viscous dissipation time, i.e. if the Ekman number is too large. We conduct simulations of the Navier–Stokes equations with no-slip boundary conditions using parameter values corresponding to a recent set of laboratory experiments, and reproduce the experimental observations and measurements. Then, we reduce the Ekman number by one and a half orders of magnitude, allowing for a better identification and quantification of the contributions to the response from the eigenmodes and the edge beams.

Los estilos APA, Harvard, Vancouver, ISO, etc.

5

Riahinezhad, Marzieh, Madeleine Hallman y J.-F. Masson. "Critical Review of Polymeric Building Envelope Materials: Degradation, Durability and Service Life Prediction". Buildings 11, n.º 7 (7 de julio de 2021): 299. http://dx.doi.org/10.3390/buildings11070299.

Texto completo

Resumen

This paper provides a critical review of the degradation, durability and service life prediction (SLP) of polymeric building envelope materials (BEMs), namely, claddings, air/vapour barriers, insulations, sealants, gaskets and fenestration. The rate of material deterioration and properties determine the usefulness of a product; therefore, knowledge of the significant degradation mechanisms in play for BEMs is key to the design of proper SLP methods. SLP seeks to estimate the life expectancy of a material/component exposed to in-service conditions. This topic is especially important with respect to the potential impacts of climate change. The surrounding environment of a building dictates the degradation mechanisms in play, and as climate change progresses, material aging conditions become more unpredictable. This can result in unexpected changes and/or damages to BEMs, and shorter than expected SL. The development of more comprehensive SLP methods is economically and environmentally sound, and it will provide more confidence, comfort and safety to all building users. The goal of this paper is to review the existing literature in order to identify the knowledge gaps and provide suggestions to address these gaps in light of the rapidly evolving climate.

Los estilos APA, Harvard, Vancouver, ISO, etc.

6

Huang, Xin Zhang, Xiu Li Zhang, Jun Rui Shi, Zhi Jia Xue, You Ning Xu y Shu Qun Wang. "Experimental Study on CH₄ / Air Diffusion Combustion on the Upper Surface of Porous Media Packed Beds". Advanced Materials Research 516-517 (mayo de 2012): 62–65. http://dx.doi.org/10.4028/www.scientific.net/amr.516-517.62.

Texto completo

Resumen

This paper experimentally study on CH4/ air co-flow diffusion combustion on the upper surface of porous media packed beds. The flame height and flame shape were reconstructed from the upper and the side of the combustor. The influence of the height of the packed bed on the flame height and flame shape is reported. It is shown that the flame height decreases rapidly and the circular diameter increases rapidly with increase the height of the packed beds.

Los estilos APA, Harvard, Vancouver, ISO, etc.

7

Rivers, James W. y Matthew G. Betts. "Postharvest Bee Diversity is High but Declines Rapidly with Stand Age in Regenerating Douglas-Fir Forest". Forest Science 67, n.º 3 (25 de marzo de 2021): 275–85. http://dx.doi.org/10.1093/forsci/fxab002.

Texto completo

Resumen

Abstract Concerns about long-term pollinator declines have made assessing bee communities a priority in nonagricultural ecosystems, including managed forests. We assessed wild bee communities in Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) stands one to 15 years after clearcut harvest in western Oregon, USA, testing the hypothesis that bee diversity would be high initially and then decline with time-dependent reductions in floral resources. We captured 2,009 individual bees that represented 67 distinct species/morphospecies in 20 genera and five families. Asymptotic estimators of bee diversity representing Shannon and Simpson diversity were greater in communities during the second half of the early seral period, indicating older early seral stands were less diverse and contained more common and dominant bee species. In addition, observed species richness and bee abundance peaked at approximately three years postharvest and declined thereafter by 20% and 30% per year, respectively. Because floral resources declined in concert with reductions in bee diversity as stands aged, food appears to be a key driver of forest bee communities. Our results indicate that postharvest Douglas-fir stands supported a diversity of bees, including important crop pollinators, but their value to bees was restricted to a relatively short window at the beginning of the early seral period.

Los estilos APA, Harvard, Vancouver, ISO, etc.

8

Zhang, Kuang, Yuxiang Wang, Yueyi Yuan y Shah Nawaz Burokur. "A Review of Orbital Angular Momentum Vortex Beams Generation: From Traditional Methods to Metasurfaces". Applied Sciences 10, n.º 3 (4 de febrero de 2020): 1015. http://dx.doi.org/10.3390/app10031015.

Texto completo

Resumen

In this paper, we review the generation of vortex beams carrying orbital angular momentum in the microwave domain. We firstly present the theory of Laguerre–Gaussian beams where it is demonstrated that they carry such type of momentum. We further provide an overview of the classical methods used to generate orbital angular momentum vortex beams, which rely on two main methods; plane wave to vortex wave conversion and direct generation using radiating antennas. Then, we present recent progress in the physics of metasurfaces devoted to the generation of vortex beams with a discussion about reflective and transmissive metasurfaces for plane wave to vortex wave conversion as well as methods to reduce the intrinsic divergence characteristics of vortex beams. Finally, we conclude on this rapidly developing research field.

Los estilos APA, Harvard, Vancouver, ISO, etc.

9

Liu, Can. "Shear Capacity Research on Transversely Reinforced Concrete Beams". Applied Mechanics and Materials 744-746 (marzo de 2015): 283–87. http://dx.doi.org/10.4028/www.scientific.net/amm.744-746.283.

Texto completo

Resumen

Inner transverse prestressed bars were used to enhance the shear capacity of concrete beams in this paper, which can be used in transformer beams to reduce the sectional size. Two transversely prestressed one ordinary concrete beams were tested and calculated by finite element method, and the following conclusions can be drawn: (a)The shear capacity of transversely prestressed concrete beam increase rapidly with the increase of the prestressing force level, which means that prestressing force level has a great influence on the shear capacity of transversely prestressed concrete beam. (b) The transverse prestressing bars can efficiently enhance the anti-crack performance of the reinforced concrete beams.

Los estilos APA, Harvard, Vancouver, ISO, etc.

10

Blanchet, Jose H. y Carlos G. Pacheco-González. "UNIFORM CONVERGENCE TO A LAW CONTAINING GAUSSIAN AND CAUCHY DISTRIBUTIONS". Probability in the Engineering and Informational Sciences 26, n.º 3 (8 de junio de 2012): 437–48. http://dx.doi.org/10.1017/s0269964812000101.

Texto completo

Resumen

A source of light is placeddinches apart from the center of a detection bar of lengthL≥d. The source spins very rapidly, while shooting beams of light according to, say, a Poisson process with rate λ. The positions of the beams, relative to the center of the bar, are recorded for those beams that actually hit the bar. Which law best describes the time-average position of the beams that hit the bar given a fixed but long time horizont? The answer is given in this paper by means of a uniform weak convergence result inL, dast→ ∞. Our approximating law includes as particular cases the Cauchy and Gaussian distributions.

Los estilos APA, Harvard, Vancouver, ISO, etc.

11

Krassowska, Julita y Marta Kosior-Kazberuk. "Failure mode in shear of steel fiber reinforced concrete beams". MATEC Web of Conferences 163 (2018): 02003. http://dx.doi.org/10.1051/matecconf/201816302003.

Texto completo

Resumen

Experimental tests were carried out to assess the failure model of steel fiber reinforced concrete beams. Experimental research was focused on observing changes in the behavior of the tested elements depending on the amount of shear reinforcement and the fiber. Model two-span beams with a cross-section of 80x180 mm and a length of 2000 mm were tested. The beams had varied stirrup spacing. The following amounts of steel fibres in concrete were used: 78.5 kg/m3 (1.0%) i 118 kg/m3 (1.5%). Concrete beams without fibres were examined at the same time. The beams were loaded in a five-point bending test until they were destroyed. Shear or bending capacity of the element was observed. Fibre reinforced concrete beams were not destroyed rapidly, but they kept their shape consistent under load. Larger number of diagonal cracks with a smaller width were observed in fibre reinforced concrete beams. Failure of concrete beams without fibres was rapid, with a characteristic brittle cracking. Steel fibres revealed the ability to transfer significant shear stress after cracking in comparison to plain concrete.

Los estilos APA, Harvard, Vancouver, ISO, etc.

12

Lekkas, Ioannis, Mark D. Frogley, Timon Achtnich y Gianfelice Cinque. "Rapidly frequency-tuneable, in-vacuum, and magnetic levitation chopper for fast modulation of infrared light". Review of Scientific Instruments 93, n.º 8 (1 de agosto de 2022): 085105. http://dx.doi.org/10.1063/5.0097279.

Texto completo

Resumen

We present an in-vacuum mechanical chopper running at high speed and integrated into a magnetic levitating motor for modulating optical beams up to 200 kHz. The compact chopper rotor allows fast acceleration (10 kHz s−1 as standard) for rapid tuning of the modulation frequency, while 1 mm diameter slots provide high optical throughput for larger infrared beams. The modulation performances are assessed using a reference visible laser and the high brightness, broadband, infrared (IR) beam of synchrotron radiation at the MIRIAM beamline B22 at Diamond Light Source, UK. For our application of IR nanospectroscopy, minimizing the temporal jitter on the modulated beam due to chopper manufacturing and control tolerances is essential to limit the noise level in measurements via lock-in detection, while high modulation frequencies are needed to achieve high spatial resolution in photothermal nanospectroscopy. When reaching the maximum chopping frequency of 200 kHz, the jitter was found to be 0.9% peak-to-peak. The described chopper now replaces the standard ball-bearing chopper in our synchrotron-based FTIR photothermal nanospectroscopy system, and we demonstrate improved spectroscopy results on a 200 nm thickness polymer film.

Los estilos APA, Harvard, Vancouver, ISO, etc.

13

Wang, Jennifer, Evan Leibner, Jaime B. Hyman, Sanam Ahmed, Joshua Hamburger, Jean Hsieh, Neha Dangayach et al. "The Mount Sinai Hospital Institute for critical care medicine response to the COVID-19 pandemic". Acute and Critical Care 36, n.º 3 (31 de agosto de 2021): 201–7. http://dx.doi.org/10.4266/acc.2021.00402.

Texto completo

Resumen

Background: The coronavirus disease 2019 (COVID-19) pandemic resulted in a surge of critically ill patients. This was especially true in New York City. We present a roadmap for hospitals and healthcare systems to prepare for a Pandemic.Methods: This was a retrospective review of how Mount Sinai Hospital (MSH) was able to rapidly prepare to handle the pandemic. MSH, the largest academic hospital within the Mount Sinai Health System, rapidly expanded the intensive care unit (ICU) bed capacity, including creating new ICU beds, expanded the workforce, and created guidelines.Results: MSH a 1,139-bed quaternary care academic referral hospital with 104 ICU beds expanded to 1,453 beds (27.5% increase) with 235 ICU beds (126% increase) during the pandemic peak in the first week of April 2020. From March to June 2020, with follow-up through October 2020, MSH admitted 2,591 COVID-19-positive patients, 614 to ICUs. Most admitted patients received noninvasive support including a non-rebreather mask, high flow nasal cannula, and noninvasive positive pressure ventilation. Among ICU patients, 68.4% (n=420) received mechanical ventilation; among the admitted ICU patients, 42.8% (n=263) died, and 47.8% (n=294) were discharged alive.Conclusions: Flexible bed management initiatives; teamwork across multiple disciplines; and development and implementation of guidelines were critical accommodating the surge of critically ill patients. Non-ICU services and staff were deployed to augment the critical care work force and open new critical care units. This approach to rapidly expand bed availability and staffing across the system helped provide the best care for the patients and saved lives.

Los estilos APA, Harvard, Vancouver, ISO, etc.

14

Gupta, Manish y Dudley Herschbach. "Slowing and Speeding Molecular Beams by Means of a Rapidly Rotating Source†". Journal of Physical Chemistry A 105, n.º 9 (marzo de 2001): 1626–37. http://dx.doi.org/10.1021/jp002640u.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

15

Abou-Shaara, Hossam F., Ahmad A. Al-Ghamdi y Abdelsalam A. Mohamed. "Honey bee colonies performance enhance by newly modified beehives". Journal of Apicultural Science 57, n.º 2 (1 de diciembre de 2013): 45–57. http://dx.doi.org/10.2478/jas-2013-0016.

Texto completo

Resumen

Abstract Honey bees have good thermoregulation and rapidly respond to any changes in the microclimatic conditions of their colonies. However, colony losses can occur during very cold or hot months. Honey bee colonies are often kept in modified beehives during such times to save the honey bees lives. In the present study, the abilities of four beehive types to enhance the performance of two honey bee races (Carniolan and Yemeni honey bees) were compared under hot and arid environmental conditions. The results indicated performance differences between the two races and between the selected beehive types. For the Carniolan honey bees, better results were obtained in colonies provided with insulated cover boxes (ICB) than in thermoregulatory beehives (TBH), insulated beehives with a back drawer (IBD), and normal beehives (NB) in that order. In contrast, better Yemeni honey bee results were obtained in the TBH, followed by ICB, NB, and finally IBD. Maintaining honey bees in a suitable beehive type is a promising method for saving honey bees lives and enhancing their performance under harsh environmental conditions.

Los estilos APA, Harvard, Vancouver, ISO, etc.

16

Capaldi, E. A. y F. C. Dyer. "The role of orientation flights on homing performance in honeybees". Journal of Experimental Biology 202, n.º 12 (15 de junio de 1999): 1655–66. http://dx.doi.org/10.1242/jeb.202.12.1655.

Texto completo

Resumen

Honeybees have long served as a model organism for investigating insect navigation. Bees, like many other nesting animals, primarily use learned visual features of the environment to guide their movement between the nest and foraging sites. Although much is known about the spatial information encoded in memory by experienced bees, the development of large-scale spatial memory in naive bees is not clearly understood. Past studies suggest that learning occurs during orientation flights taken before the start of foraging. We investigated what honeybees learn during their initial experience in a new landscape by examining the homing of bees displaced after a single orientation flight lasting only 5–10 min. Homing ability was assessed using vanishing bearings and homing speed. At release sites with a view of the landmarks immediately surrounding the hive, ‘first-flight’ bees, tested after their very first orientation flight, had faster homing rates than ‘reorienting foragers’, which had previous experience in a different site prior to their orientation flight in the test landscape. First-flight bees also had faster homing rates from these sites than did ‘resident’ bees with full experience of the terrain. At distant sites, resident bees returned to the hive more rapidly than reorienting or first-flight bees; however, in some cases, the reorienting bees were as successful as the resident bees. Vanishing bearings indicated that all three types of bees were oriented homewards when in the vicinity of landmarks near the hive. When bees were released out of sight of these landmarks, hence forcing them to rely on a route memory, the ‘first-flight’ bees were confused, the ‘reorienting’ bees chose the homeward direction except at the most distant site and the ‘resident’ bees were consistently oriented homewards.

Los estilos APA, Harvard, Vancouver, ISO, etc.

17

Oda, Mikio, Binti Ibrahim Anis Farhana y Y. Nakamura. "A Delamination in a Three Layers Laminated Beam Subjected to Thermal Gradient". Advanced Materials Research 845 (diciembre de 2013): 367–71. http://dx.doi.org/10.4028/www.scientific.net/amr.845.367.

Texto completo

Resumen

A laminated beam containing an initial delamination subjected to thermal gradient is analyzed on the basis of classical beam theory. The axial forces are induced in the parts of the constituent beams above and below the delamination. For the case where crack faces are open, a nonlinear equation for determining the in-plane forces is derived by modeling the delaminated part as two lapped beams hinged at both ends, and by imposing the compatibility condition of the deformations of the two beams. Numerical solutions are obtained for some model beams. It is shown that the relative displacement at the center of the delamination increases gradually with the increase very rapidly, i.e., local delamination buckling occurs. Energy release rate is small for temperature gradient below the critical value, but it takes a large value when the temperature gradient is increased beyond the critical value.

Los estilos APA, Harvard, Vancouver, ISO, etc.

18

Arismendi, Nolberto, Solange Caro, María Paz Castro, Marisol Vargas, Gustavo Riveros y Tomas Venegas. "Impact of Mixed Infections of Gut Parasites Lotmaria passim and Nosema ceranae on the Lifespan and Immune-related Biomarkers in Apis mellifera". Insects 11, n.º 7 (8 de julio de 2020): 420. http://dx.doi.org/10.3390/insects11070420.

Texto completo

Resumen

Lotmaria passim currently appears to be the predominant trypanosome in honey bees worldwide. Although, the specific effects of L. passim by single or mixed with other gut parasites such as Nosema ceranae on honey bees’ health is still unclear. We consequently measured bees’ survival, parasite loads, the expression of antimicrobial peptides (AMPs) and vitellogenin gene. Thus, (1) bees naturally infected with L. passim, (2) healthy bees inoculated with Nosema ceranae, (3) bees naturally infected with L. passim and inoculated with N. ceranae and (4) healthy bees (control) were maintained under controlled conditions. Honey bees infected with N. ceranae or with mixed infections of L. passim and N. ceranae had significantly lower survival rates than the control group at 20 days post-inoculation (dpi). A competitive suppression was also detected, provided that the L. passim load was significantly affected by the presence of N. ceranae at 15 dpi. Expressions of the AMPs defensin and hymenoptaecin rapidly (two hours post-inoculation) increased in bees infected with N. ceranae and mixed infections. However, this effect was not continuous. In fact, expressions of abaecin, defensin, hymenoptaecin and vitellogenin decreased drastically at 15 dpi in bees with both single and mixed infections. The decrease in the expression of AMPs and vitellogenin throughout this period was consistent with the reduced survivals observed in this study, indicating that mixed infections of L. passim and N. ceranae, and even into a scenario of competition between them, may have a synergic effect on the survival and immune-related gene expressions (biomarkers) of worker bees.

Los estilos APA, Harvard, Vancouver, ISO, etc.

19

Wang, Zhuang, Bing Wang, Haozhe Jiang y Ping Zhuge. "Experimental Study on the Flexural and Shear Performance of Concrete Beams Strengthened with Prestressed CFRP Tendons". Applied Sciences 14, n.º 3 (1 de febrero de 2024): 1237. http://dx.doi.org/10.3390/app14031237.

Texto completo

Resumen

To investigate the influence of external prestressing with carbon fiber-reinforced polymer (CFRP) tendons on the flexural and shear performance of reinforced concrete beams, a total of six simply supported beams with a length of 3.5 m and two two-span continuous beams with a length of 7 m were studied. The influences of the prestressing level of CFRP tendons, the pattern of straight-line and flexural reinforcement of externally prestressed CFRP tendons, and the existence of initial cracks in the beams on the flexural bearing capacity of the reinforced beams were explored through modeling tests. The calculating equation for anticipating the ultimate flexural bearing capacity of concrete beams reinforced with externally prestressed CFRP tendons was modified based on the test results. The findings indicate that the flexural bearing capacity of the test beams was significantly enhanced through both flexural and straight-line reinforcement. Specifically, the ultimate flexural bearing capacity of the simply supported beams exhibited improvements of approximately 160% and 170%, respectively, whereas the ultimate flexural bearing capacity of the continuous beams was enhanced by approximately 113% through the reinforcement of flexural arrangement. Additionally, the shear resistance capacity of the concrete beams was notably improved through the flexural arrangement reinforcement, and the shear resistance capacity of the beams exhibited a substantial increase as the prestressing level of the CFRP tendons increased. The flexural moments in the vicinity of the support point of the reinforced beam exhibited an increase ranging from 41.7% to 112.5% when the stirrup strains started to escalate rapidly. Additionally, the rigidity of the test beams showed a close correlation with both the prestressing level and the existence of initial cracks.

Los estilos APA, Harvard, Vancouver, ISO, etc.

20

Gomes, Cássia R. A., Mateus A. M. Batista, Yara M. M. Ferraz, Matheus F. Trivellato, Gustavo A. Siniscalchi, Gustavo V. Polycarpo, Everlon C. Rigobelo, David De Jong y Daniel Nicodemo. "A Hive Entrance System That Directs Honey Bees Inside or Outside a Greenhouse Reduced Colony Decline While Effectively Pollinating Zucchini Squash". Agriculture 14, n.º 6 (23 de mayo de 2024): 805. http://dx.doi.org/10.3390/agriculture14060805.

Texto completo

Resumen

Honey bee colonies rapidly decline when confined to greenhouses, increasing pollination rental costs as they need to be replaced frequently. We tested a hive system with entrances that can be manipulated to direct bees inside or outside greenhouses containing a zucchini crop. In one greenhouse, the bees could only forage inside for 15 days; in another, bees were directed to the inside from 5 to 9 a.m., after which they only foraged outside. This procedure was repeated two more times in each greenhouse with new hives. Data were collected on how the number of bee flower visits affected fruit production, the frequency of flower visits, and the amount of bee brood and food in the hives. Flowers visited by bees four times or more set more and larger fruit. The frequency of flower visits by bees from the hives confined to the greenhouse was reduced after eight days; it was not reduced in the greenhouse with bees that could forage outside. The bee brood area was reduced in the colonies that were confined to the greenhouse, while it was maintained in the semi-confined hives. The hives with controllable entrances proved effective for pollination, while causing less damage to the bees.

Los estilos APA, Harvard, Vancouver, ISO, etc.

21

Qu, Guangzhen, Pingming Huang, Guangli Zhou y Sizhong Lv. "Experimental Research on Fatigue Behavior of Existing Reinforced Concrete Beams". Advances in Civil Engineering 2020 (12 de octubre de 2020): 1–13. http://dx.doi.org/10.1155/2020/8858945.

Texto completo

Resumen

In order to obtain the law of the fatigue damage development of reinforced concrete hollow beams that has been in service for 24 years, its solid hollow beams were removed and transported to the laboratory for loading test. Two beams were selected for static loading to obtain the ultimate flexural bearing capacity, and three beams were, respectively, subjected to constant-amplitude fatigue loading with different load amplitudes. The static and dynamic behaviors of the beams were monitored in the fatigue test. The fatigue failure of the beams showed that the outermost rebar at the butt weld fractured at first, and the crack width at the fracture position of the steel bar was about 0.3 mm, which was largest in all cracks. After a rebar was broken, midspan deflection and flexibility increased by approximately 20% and 10%, respectively, relative to the initial state. The damage developed rapidly in the following range: (1) the first 10,000 fatigue cycles; (2) after fatigue fracture of the rebar; and in the intermediate stage of fatigue test, the damage development was relatively stable. As the loading amplitude increased, the stiffness degradation and the cumulative damage that occured under the same loading cycle were more significant.

Los estilos APA, Harvard, Vancouver, ISO, etc.

22

Okada, Ryuichi, Hidetoshi Ikeno, Hitoshi Aonuma, Midori Sakura y Etsuro Ito. "Honey Bee Waggle Dance as a Model of Swarm Intelligence". Journal of Robotics and Mechatronics 35, n.º 4 (20 de agosto de 2023): 901–10. http://dx.doi.org/10.20965/jrm.2023.p0901.

Texto completo

Resumen

Honey bees are social insects that form colonies (hives), which often consist of more than 10,000 individuals. In a colony, bees allocate jobs (division of labor) and work cooperatively and intelligently to maintain the colony’s activity, such as nursing broods, cleaning, and guarding against enemies. Among worker bees, only forager bees collect food, and success in finding food directly influences colony survival. For more efficient foraging, honey bees share location information pertaining to profitable food sources through specific behavior called “waggle dances.” During such dances, the direction and distance from the hive to the food source are encoded as body movements. Other foragers follow the dancing bees and receive location information. Some of these bees then fly to the advertised location to find the food source. Some of these “recruited bees” subsequently dance to recruit new bees. This process is then repeated. Consequently, many foragers visit the food source, and a colony can rapidly and flexibly collect large amounts of food even in foraging environment that can suddenly change (e.g., flowers disappear or nectar flux increases/decreases). To achieve effective food collection through the waggle dance, the behavior of both the dancers and followers probably contains information for an implementation of “swarm intelligence.” In this review, we introduce the properties of dance behavior at the levels of dancers, followers, and colonies. We found that errors in waggle dance information play an important role in adaptive foraging in dynamically changing environments.

Los estilos APA, Harvard, Vancouver, ISO, etc.

23

LISAUSKAS, Tadas, Mindaugas AUGONIS, Tadas ZINGAILA y Mario Rui Tiago ARRUDA. "Stiffness and Strength Analysis of Flexural RC beams strengthened with CFRP Sheets Considering the Influence of Pre-cracking". Mechanics 26, n.º 4 (15 de septiembre de 2020): 277–84. http://dx.doi.org/10.5755/j01.mech.26.4.25064.

Texto completo

Resumen

This paper presents experimental, numerical and analytical analysis of newly cast and pre-cracking flexural reinforced concrete beams strengthened with CFRP. In total, 9 intermediate-scale composite beams were cast and tested using 4-point bending test setup. Midspan deflection, width of the cracks, concrete and CFRP strains were measured during the experimental program. Clear efficiency of composite pre-cracked beams was observed in comparison to newly cast beams: enhanced flexural capacity and increased stiffness after appearance of primary cracks in tension zone. Good agreement was found comparing experimental and theoretical (EC2) deflections of RC beams strengthened with CFRP. However, for more detailed verification, the analysis should be extended with more specimens. The shear stress at the end of CFRP sheets between the concrete and CFRP increased rapidly until reaching maximum slip value, when the reinforced concrete beam strengthened with CFRP reaches 60-90 % utilization of load bearing capacity. All experimental results were compared with numerical and analytical calculations. Experimental, numerical and analytical results were in sufficiently good agreement.

Los estilos APA, Harvard, Vancouver, ISO, etc.

24

Balbinot, Roberto y Alessandro Fabbri. "Amplifying the Hawking Signal in BECs". Advances in High Energy Physics 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/713574.

Texto completo

Resumen

We consider simple models of Bose-Einstein condensates to study analog pair-creation effects, namely, the Hawking effect from acoustic black holes and the dynamical Casimir effect in rapidly time-dependent backgrounds. We also focus on a proposal by Cornell to amplify the Hawking signal in density-density correlators by reducing the atoms’ interactions shortly before measurements are made.

Los estilos APA, Harvard, Vancouver, ISO, etc.

25

Xie, Tian, Jie Ding, Xiaoxu Han, Huizhen Jia, Yang Yang, Shuang Liang, Wenxin Wang, Wenguang Liu y Wei Wang. "Wound dressing change facilitated by spraying zinc ions". Materials Horizons 7, n.º 2 (2020): 605–14. http://dx.doi.org/10.1039/c9mh01255a.

Texto completo

Resumen

It is a tough task in clinic to remove and refuel the dressing. Therefore, we have explored a bioinspired dressing which can be swiftly detached from wound beds and rapidly strengthened during the dressing change procedures.

Los estilos APA, Harvard, Vancouver, ISO, etc.

26

I. Jawad, Ali AL-Sajad, Hassan F. Hassan y Mohammed H. Kadem. "A REVIEW OF SHEAR BEHAVIOR OF CONCRETE BEAMS REINFORCED BY FRP BARS". Journal of Engineering and Sustainable Development 25, Special (20 de septiembre de 2021): 4–31. http://dx.doi.org/10.31272/jeasd.conf.2.4.4.

Texto completo

Resumen

Using fibre-reinforced polymer (FRP) in the concrete structures was rapidly increased throughout the past two decades. Corrosion-free properties and the high ratio of strength-to-weight of the FRP reinforcement has led to the significant increase of structures’ service life. In the present work, the earlier studies that are associated with shear behaviour of the beams that have been reinforced by the FRP bars are reviewed. Many researchers have investigated shear behavior of the beams of concrete that have been reinforced by the FRP bars and determined their capacity. Some of them have per-formed experimental investigations through the testing of several beams with varying some of the parameters, whereas the others have been theoretical for estimating shear capacity of the beam. This study presents as well, a review for all of the codes and researcher equations for shear design of the beams that have been rein-forced by the FRP bars.

Los estilos APA, Harvard, Vancouver, ISO, etc.

27

Ju, Hyunjin, Meirzhan Yerzhanov, Alina Serik, Deuckhang Lee y Jong R. Kim. "Statistical and Reliability Study on Shear Strength of Recycled Coarse Aggregate Reinforced Concrete Beams". Materials 14, n.º 12 (16 de junio de 2021): 3321. http://dx.doi.org/10.3390/ma14123321.

Texto completo

Resumen

The consumption of structural concrete in the construction industry is rapidly growing, and concrete will remain the main construction material for increasing urbanization all over the world in the near future. Meanwhile, construction and demolition waste from concrete structures is also leading to a significant environmental problem. Therefore, a proper sustainable solution is needed to address this environmental concern. One of the solutions can be using recycled coarse aggregates (RCA) in reinforced concrete (RC) structures. Extensive research has been conducted in this area in recent years. However, the usage of RCA concrete in the industry is still limited due to the absence of structural regulations appropriate to the RCA concrete. This study addresses a safety margin of RCA concrete beams in terms of shear capacity which is comparable to natural coarse aggregates (NCA) concrete beams. To this end, a database for reinforced concrete beams made of recycled coarse aggregates with and without shear reinforcement was established, collecting the shear specimens available from various works in the existing literature. The database was used to statistically identify the strength margin between RCA and NCA concrete beams and to calculate its safety margin based on reliability analysis. Moreover, a comparability study of RCA beams was conducted with its control specimens and with a database for conventional RC beams.

Los estilos APA, Harvard, Vancouver, ISO, etc.

28

Hung, Keng-Lou James, Jennifer M. Kingston, Adrienne Lee, David A. Holway y Joshua R. Kohn. "Non-native honey bees disproportionately dominate the most abundant floral resources in a biodiversity hotspot". Proceedings of the Royal Society B: Biological Sciences 286, n.º 1897 (20 de febrero de 2019): 20182901. http://dx.doi.org/10.1098/rspb.2018.2901.

Texto completo

Resumen

Most plant–pollinator mutualisms are generalized. As such, they are susceptible to perturbation by abundant, generalist, non-native pollinators such as the western honey bee ( Apis mellifera ), which can reach high abundances and visit flowers of many plant species in their expansive introduced range. Despite the prevalence of non-native honey bees, their effects on pollination mutualisms in natural ecosystems remain incompletely understood. Here, we contrast community-level patterns of floral visitation by honey bees with that of the diverse native pollinator fauna of southern California, USA. We show that the number of honey bees visiting plant species increases much more rapidly with flower abundance than does that of non-honey bee insects, such that the percentage of all visitors represented by honey bees increases with flower abundance. Thus, honey bees could disproportionately impact the most abundantly blooming plant species and the large numbers of both specialized and generalized pollinator species that they sustain. Honey bees may preferentially exploit high-abundance floral resources because of their ability to recruit nest-mates; these foraging patterns may cause native insect species to forage on lower-abundance resources to avoid competition. Our results illustrate the importance of understanding foraging patterns of introduced pollinators in order to reveal their ecological impacts.

Los estilos APA, Harvard, Vancouver, ISO, etc.

29

Tang, Bofeng, Haihong Che, Gary P. Zank y Vladimir I. Kolobov. "Suprathermal Electron Transport and Electron Beam Formation in the Solar Corona". Astrophysical Journal 954, n.º 1 (22 de agosto de 2023): 43. http://dx.doi.org/10.3847/1538-4357/ace7be.

Texto completo

Resumen

Abstract Electron beams that are commonly observed in the corona were discovered to be associated with solar flares. These “coronal” electron beams are found ≥300 Mm above the acceleration region and have velocities ranging from 0.1c up to 0.6c. However, the mechanism for producing these beams remains unclear. In this paper, we use kinetic transport theory to investigate how isotropic suprathermal energetic electrons escaping from the acceleration region of flares are transported upwardly along the magnetic field lines of flares to develop coronal electron beams. We find that magnetic focusing can suppress the diffusion of Coulomb collisions and background turbulence and sharply collimate the suprathermal electron distribution into beams with the observed velocity within the observed distance. A higher bulk velocity is produced if energetic electrons have harder energy spectra or travel along a more rapidly expanding coronal magnetic field. By modeling the observed velocity and location distributions of coronal electron beams, we predict that the temperature of acceleration regions ranges from 5 × 106 to 2 × 107 K. Our model also indicates that the acceleration region may have a boundary where the temperature abruptly decreases so that the electron beam velocity can become more than triple (even up to 10 times) the background thermal velocity and produce the coronal type III radio bursts.

Los estilos APA, Harvard, Vancouver, ISO, etc.

30

SESHADRI, S. R. "Anomalous absorption of the circularly polarized electromagnetic beams near the plasma frequency in a magnetized electron plasma". Journal of Plasma Physics 73, n.º 3 (junio de 2007): 315–30. http://dx.doi.org/10.1017/s0022377806004697.

Texto completo

Resumen

AbstractThe propagation of circularly polarized electromagnetic beams along the magnetostatic field in an electron plasma is investigated. As a consequence of a strong interaction with the medium, the beam spreads rapidly on propagation near the cutoff frequencies and the cyclotron resonant frequency of the corresponding plane waves, as well as near the plasma frequency. The power absorption for unit length near the cyclotron frequency and the plasma frequency are determined. For tightly focused beams, there is significant power absorption near the plasma frequency as compared with that at the cyclotron resonant frequency.

Los estilos APA, Harvard, Vancouver, ISO, etc.

31

Wang, Hai Chao, Zhen Tian Xu y Wen Ting Liu. "The Creep Impact on the Performance of Super-Long Reinforced Concrete Structures". Advanced Materials Research 790 (septiembre de 2013): 291–94. http://dx.doi.org/10.4028/www.scientific.net/amr.790.291.

Texto completo

Resumen

In order to study the deformation of super-long structures under the influence of creep , take fully advantage of orthogonal design to make nine series reinforced concrete beams of shrinkage-compensating to deeply analyze the function performanced by creep of the reinforced concrete structure and obtain that the time-deflection curves of volume deformation and creep deformation of shrinkage-compensating reinforced concrete beams. The results show that the creep of beams develops rapidly early and the slow development of the late. The greater the expansion stress is in the early, the greater the shrinkage strain in the late, the greater the deformation of volume. So, the appropriate mixing ratio of expansive agent is given by the experiment. It provides a scientific basis for seamless design of super-long structures.

Los estilos APA, Harvard, Vancouver, ISO, etc.

32

Kotlyar, Nathan. "Formulas for Beams with Semi-rigid Connections". Engineering Journal 33, n.º 4 (31 de diciembre de 1996): 142–46. http://dx.doi.org/10.62913/engj.v33i4.672.

Texto completo

Resumen

This paper presents practical formulas for beams with semi-rigid connections of variable stiffness, and describes certain limitations for application of these formulas. Using the tables of formulas, the engineer is able to rapidly determine the effect of a partially restrained connection. A practical example illustrates the application of the formulas.

Los estilos APA, Harvard, Vancouver, ISO, etc.

33

Laxdal, R. E., A. C. Morton y P. Schaffer. "Radioactive Ion Beams and Radiopharmaceuticals". Reviews of Accelerator Science and Technology 06 (enero de 2013): 37–57. http://dx.doi.org/10.1142/s179362681330003x.

Texto completo

Resumen

Experiments performed at radioactive ion beam facilities shed new light on nuclear physics and nuclear structure, as well as nuclear astrophysics, materials science and medical science. The many existing facilities, as well as the new generation of facilities being built and those proposed for the future, are a testament to the high interest in this rapidly expanding field. The opportunities inherent in radioactive beam facilities have enabled the search for radioisotopes suitable for medical diagnosis or therapy. In this article, an overview of the production techniques and the current status of RIB facilities and proposals will be presented. In addition, accelerator-generated radiopharmaceuticals will be reviewed.

Los estilos APA, Harvard, Vancouver, ISO, etc.

34

Nicodemo, Daniel, Euclides Braga Malheiros, David De Jong y Regina Helena Nogueira Couto. "Improved Pollination Efficiency and Reduced Honey Bee Colony Decline in Greenhouses by Allowing Access to the Outside During Part of the Day". Sociobiology 65, n.º 4 (11 de octubre de 2018): 714. http://dx.doi.org/10.13102/sociobiology.v65i4.3455.

Texto completo

Resumen

Although honey bees are efficient pollinators of many crops cultivated in greenhouses, it is difficult to maintain colony strength and consequently pollination efficiency. Many bees die under greenhouse conditions and the colonies rapidly weaken. We examined the effect of adaptations to the hive entrance that allowed control of whether and when bees had access to the outside environment to see how it would affect pollination efficiency and colony condition in greenhouses with flowering cucumber (Cucumis sativus) plants in comparison with colonies that remained constantly inside the greenhouse, previously left in a dark environment or not. We recorded the type and period of visitation to the cucumber flowers, numbers of honey bees entering and leaving the two entrance hives and the effect of this type of management on the quantity of brood and food. Fiveframe Langstroth “nucleus” colonies were equipped with two 30 square centimeter entrances and two 3.0 cm diameter circular openings. Allowing the bees to make visits outside the greenhouse in early morning with redirection of bees into the greenhouse at 8.30 a.m. did not reduce visitation to cucumber flowers in the greenhouse. Maintaining colonies in the greenhouse reduced brood area and food stores. These losses were significantly reduced in colonies that had access outside the greenhouse during the early morning. Another advantage of alternating access to the inside and the outside of the greenhouse was that there was less possibility of interactions between bees and people working on the crop, and also pesticides application could be made without directly affecting foraging bees.

Los estilos APA, Harvard, Vancouver, ISO, etc.

35

Zeinali, Elahe, Ali Nazari y Hossein Showkati. "Numerical Evaluation of Lateral Torsional Buckling of PFRP Channel Beams under Pure Bending". Sustainability 16, n.º 1 (28 de diciembre de 2023): 303. http://dx.doi.org/10.3390/su16010303.

Texto completo

Resumen

The use of pultruded fiber reinforced polymers (PFRPs) in strengthening and sustainable design of bridges and other structures exposed to corrosion and resistance reduction factors is growing rapidly. However, a comprehensive understanding of the structural behavior of these materials under various loading conditions is crucial to unlock their full potential and promote their wider use in diverse structural and industrial applications. Pultrusion profiles can be also used as beams in bridges. One important aspect of the structural behavior of PFRPs is their buckling behavior, particularly in thin-walled open cross sections. Lateral torsional buckling is a probable instability mode for beams with thin-walled open cross sections that are not laterally restrained along their span. Therefore, research on the buckling behavior of PFRP members is essential. In this study, the analytical responses of channel-shaped PFRP beams in bridges under pure bending are calculated using an equation in the Eurocode 3 regulation. The buckling behavior of these beams is then investigated through numerical modeling using the finite element package Abaqus. A total of 75 specimens of PFRP channel profiles with different thicknesses in various spans and lateral restraint conditions are studied for their lateral-torsional buckling behavior. This study uniquely explores the behavior of PFRP beams with lateral restraints, a novel aspect in the field of lateral-torsional buckling research of PFRP beams. The results show that the analytical equation used for these beams needs to be modified to more accurately estimate the buckling loads of FRP beams under the conditions studied in this paper.

Los estilos APA, Harvard, Vancouver, ISO, etc.

36

Fukumitsu, Nobuyoshi. "Particle Beam Therapy for Cancer of the Skull Base, Nasal Cavity, and Paranasal Sinus". ISRN Otolaryngology 2012 (31 de mayo de 2012): 1–6. http://dx.doi.org/10.5402/2012/965204.

Texto completo

Resumen

Particle beam therapy has been rapidly developed in these several decades. Proton and carbon ion beams are most frequently used in particle beam therapy. Proton and carbon ion beam radiotherapy have physical and biological advantage to the conventional photon radiotherapy. Cancers of the skull base, nasal cavity, and paranasal sinus are rare; however these diseases can receive the benefits of particle beam radiotherapy. This paper describes the clinical review of the cancer of the skull base, nasal cavity, and paranasal sinus treated with proton and carbon ion beams, adding some information of feature and future direction of proton and carbon ion beam radiotherapy.

Los estilos APA, Harvard, Vancouver, ISO, etc.

37

Jones, K. W., W. M. Kwiatek, B. M. Gordon, A. L. Hanson, J. G. Pounds, M. L. Rivers, S. R. Sutton et al. "X-Ray Microscopy Using Collimated and Focussed Synchrotron Radiation*". Advances in X-ray Analysis 31 (1987): 59–68. http://dx.doi.org/10.1154/s0376030800021844.

Texto completo

Resumen

X-ray microscopy is a field that has developed rapidly in recent years. Two different approaches have been used. Zone plates have been employed to produce focussed beams with sizes as low as 0.07 pm for x-ray energies below 1 keV. Images of biological materials and elemental maps for major and minor low Z have been produced using above and below absorption edge differences. At higher energies collimators and focussing mirrors have been used to make small diameter beams for excitation of characteristic K— or L-x rays of all elements in the periodic table.

Los estilos APA, Harvard, Vancouver, ISO, etc.

38

Shi, Danrong, Xiamin Hu, Jing Zhang y Hao Du. "Shear stiffness of notched connectors in glue laminated timber-concrete composite beams under fire conditions". BioResources 17, n.º 4 (28 de septiembre de 2022): 6397–410. http://dx.doi.org/10.15376/biores.17.4.6397-6410.

Texto completo

Resumen

Shear connectors ensure effective interaction between wood beams and concrete slabs of composite beams, and their properties noticeably affect the fire resistance of timber-concrete composite beams. To investigate the shear stiffness of notched connectors in glued laminated timber (GLT)-concrete composite beams under fire conditions, 16 shear tests were conducted. The effects of fire duration and notch length on shear properties of the connectors for a given spacing were studied. The fire tests indicated that the reduction of the notch length from 200 mm to 150 mm remarkably affected the failure mode of the shear specimens, changing from compression failure of notched wood to shear failure of notched concrete. The increase in fire duration reduced effective width of the notched wood, negatively affected the shear stiffness and shear capacity of the connectors, and the shear stiffness decreased more rapidly. The notch length did not have a substantial effect on the shear stiffness of connectors. Based on the experimental results, an analytical model to estimate the shear stiffness of notched connectors in GLT-concrete beam under fire conditions was established.

Los estilos APA, Harvard, Vancouver, ISO, etc.

39

Stepanov, Anton D., John J. Barnard, Alex Friedman, Erik P. Gilson, David P. Grote, Qing Ji, Igor D. Kaganovich, Arun Persaud, Peter A. Seidl y Thomas Schenkel. "Optimizing beam transport in rapidly compressing beams on the neutralized drift compression experiment – II". Matter and Radiation at Extremes 3, n.º 2 (marzo de 2018): 78–84. http://dx.doi.org/10.1016/j.mre.2018.01.001.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

40

Zhou, Xinyi, Zongjie Zhu, Xiangsheng Xie, Lishuang Yao, Fan Fan y Yaqin Zhou. "Broadband Vortex Beam Modulating System Based on Electrically Controlled Liquid Crystal Devices". Photonics 10, n.º 9 (4 de septiembre de 2023): 1012. http://dx.doi.org/10.3390/photonics10091012.

Texto completo

Resumen

Vortex beams with helical phase wavefronts have recently emerged as a research hotspot because of their widespread applications such as ultra-high dimensional information encoding, quantum entanglement, and data transmission due to their unique properties. Research, as of yet, on the easy preparation of vector vortex beams is hindered by technical bottlenecks such as large mechanical modulation errors and limited bandwidths of meta-structured devices in spite of the massive experimental and theoretical breakthroughs in the generation of vortex beams that have been made. To make up for the deficiency in this area, we propose here a broadband vortex beam modulating system based on electrically controlled liquid crystal (LC) devices. An electrically controlled LC q-plate and an LC broadband polarization grating (PG) are integrated in the system as the crux devices. The system enables pure vortex-phase modulation within a wide spectral range in the visible spectrum and electrical control on the output beam intensity of the vortex and Gaussian components. Experiments at different voltages of 533 nm and 632.8 nm were conducted for validation. This system overcomes the complexity and stringent optical path requirements of traditional methods for generating vortex beams, offering an efficient, convenient, and rapidly tunable approach for generating vortex beams that is easily and highly integrable.

Los estilos APA, Harvard, Vancouver, ISO, etc.

41

Banluta, Andre Russell F. y Renelene A. Macabeo. "“Bead to death,” Fibromuscular Dysplasia Presenting as A Rapidly Enlarging Right Anterior Axillary Mass". Philippine Journal of Cardiology 52, n.º 2 (11 de noviembre de 2024): 43–49. http://dx.doi.org/10.69944/pjc.9b2ebbb13f.

Texto completo

Resumen

Fibromuscular dysplasia (FMD) is a rare non-inflammatory, non-atherosclerotic arterial disease characterized by abnormal cellular proliferation and distorted architecture. It commonly affects the renal and extracranial carotid and vertebral arteries, but nearly all arterial beds may be affected, and multivessel involvement is common. We report a rare case of a 31-year-old Filipino female who presented with a rapidly enlarging right anterior axillary mass. Initial consideration was a bleeding soft tissue sarcoma as seen on chest CT scan, while whole abdominal CT scan with IV contrast revealed incidental findings of multiple aneurysms in the superior mesenteric artery, both renal arteries and right common iliac artery, suggestive of fibromuscular dysplasia. Further vascular imaging studies showed a looped left internal carotid, and a tortuous left brachial artery with beading pattern.

Los estilos APA, Harvard, Vancouver, ISO, etc.

42

Morim, Derek R., Amos Meeks, Ankita Shastri, Andy Tran, Anna V. Shneidman, Victor V. Yashin, Fariha Mahmood, Anna C. Balazs, Joanna Aizenberg y Kalaichelvi Saravanamuttu. "Opto-chemo-mechanical transduction in photoresponsive gels elicits switchable self-trapped beams with remote interactions". Proceedings of the National Academy of Sciences 117, n.º 8 (6 de febrero de 2020): 3953–59. http://dx.doi.org/10.1073/pnas.1902872117.

Texto completo

Resumen

Next-generation photonics envisions circuitry-free, rapidly reconfigurable systems powered by solitonic beams of self-trapped light and their particlelike interactions. Progress, however, has been limited by the need for reversibly responsive materials that host such nonlinear optical waves. We find that repeatedly switchable self-trapped visible laser beams, which exhibit strong pairwise interactions, can be generated in a photoresponsive hydrogel. Through comprehensive experiments and simulations, we show that the unique nonlinear conditions arise when photoisomerization of spiropyran substituents in pH-responsive poly(acrylamide-co-acrylic acid) hydrogel transduces optical energy into mechanical deformation of the 3D cross-linked hydrogel matrix. A Gaussian beam self-traps when localized isomerization-induced contraction of the hydrogel and expulsion of water generates a transient waveguide, which entraps the optical field and suppresses divergence. The waveguide is erased and reformed within seconds when the optical field is sequentially removed and reintroduced, allowing the self-trapped beam to be rapidly and repeatedly switched on and off at remarkably low powers in the milliwatt regime. Furthermore, this opto-chemo-mechanical transduction of energy mediated by the 3D cross-linked hydrogel network facilitates pairwise interactions between self-trapped beams both in the short range where there is significant overlap of their optical fields, and even in the long range––over separation distances of up to 10 times the beam width––where such overlap is negligible.

Los estilos APA, Harvard, Vancouver, ISO, etc.

43

Guffey, Sarah K., Stephanie J. Slater, Sharon p. Schleigh, Timothy F. Slater y Inge Heyer. "Surveying Geology Concepts In Education Standards For A Rapidly Changing Global Context". Contemporary Issues in Education Research (CIER) 9, n.º 4 (3 de octubre de 2016): 167–88. http://dx.doi.org/10.19030/cier.v9i4.9788.

Texto completo

Resumen

Internationally much attention is being paid to which of a seemingly endless list of scientific concepts should be taught to schoolchildren to enable them to best participate in the global economy of the 21st Century. In regards to science education, the concepts framing the subject of geology holds exalted status as core scientific principles in the Earth and space sciences domain across the globe. Economic geology plays a critical role in the global economy, historical geology guides research into predictions related by global climate change, and environmental geology helps policy makers understand the impact of human enterprises on the land, among many other geological sciences-laden domains. Such a situation begs the question of which geology concepts are being advocated in schools. Within the U.S. where there is no nationally adopted curriculum, careful comparative analysis reveals surprisingly little consensus among policy makers and education reform advocates about which geology concepts, if any, should be included in the curriculum. This lack of consensus manifests itself in few traditional or modern geology concepts being taught to U.S. school children.

Los estilos APA, Harvard, Vancouver, ISO, etc.

44

Li, Xiu, Hongbing Zhu, Zhenghao Fu, Peng Liu y Changhuang Xia. "Influence of Volume-to-Surface Area Ratio on the Creep Behavior of Steel Fiber Ceramsite Concrete Beams". Coatings 12, n.º 7 (10 de julio de 2022): 977. http://dx.doi.org/10.3390/coatings12070977.

Texto completo

Resumen

To explore the influence of the volume-to-surface area ratio (V/S) on the creep of ceramsite concrete beams, the creep performance of ceramsite concrete beams with different V/S was studied through a long-term deformation observation test, theoretical derivation analysis and finite element modeling. First, by observing the creep deflection of ceramsite concrete beams with five different V/Ss for 180 days, the relationship between creep deflection and loading time as well as the influence of V/S on creep deflection were obtained. Then, referring to the ACI209 and ACI435 creep coefficient calculation formula, the creep theory of ceramsite concrete beams involving V/S was established. Finally, the numerical model was built according to the test parameters. The results showed that the growth rate of the creep of ceramsite concrete beams increased rapidly in the early stage, but gradually slowed down with the passage of time and tended to be stable after 120 days of loading. The V/S had a significant impact on the creep of ceramsite concrete beams. In the first 7 days, the creep growth rate of each beam was approximately the same. Thereafter, the higher the V/S was, the lower the creep became. After 28 days, the creep of ceramsite concrete beams with varied V/Ss showed sharp differences. After the V/S exceeded 30, the increasing V/S could effectively reduce the creep value and the creep growth rate under a long-term load. The calculated results were in good agreement with the measured values, which fully reflected its creep variation. The finite element simulation further verified the influence of V/S on the creep of ceramsite concrete beams and the reliability of the creep calculation formula.

Los estilos APA, Harvard, Vancouver, ISO, etc.

45

Cid, Patricio, Oscar Pérez-Priego, Francisco Orgaz y Helena Gómez-Macpherson. "Short- and mid-term tillage-induced soil CO2 efflux on irrigated permanent- and conventional-bed planting systems with controlled traffic in southern Spain". Soil Research 51, n.º 5 (2013): 447. http://dx.doi.org/10.1071/sr13082.

Texto completo

Resumen

Use of permanent beds combined with controlled traffic (PB) has been proposed as an alternative planting system for reducing soil erosion and compaction while increasing soil organic carbon (SOC) in irrigated, annual-crop based systems in Mediterranean conditions. The objective of this study was to characterise, in space (beds and furrows with and without traffic) and time (hours, days, and weeks), soil CO2 efflux in PB compared with conventionally tilled bed planting (CB) and with a variant of PB in which subsoiling was performed in trafficked furrows (DPB). The three treatments were combined with controlled traffic. Tillage resulted in abrupt CO2 effluxes that lowered rapidly within hours. However, in CB, soil CO2 effluxes increased again significantly 12 days after tillage compared with PB or DPB. These differences were due to higher emissions from beds than from furrows where the soil had been compacted during the harrowing that formed the beds. In DPB, CO2 effluxes increased in furrows with traffic after subsoiling and the effect was maintained during the study despite subsequent traffic. Soil CO2 efflux increased with soil temperature (measured concomitantly) except after soil tillage. Tillage reduced SOC in both CB and DPB compared with PB.

Los estilos APA, Harvard, Vancouver, ISO, etc.

46

Tang, Bofeng, Haihong Che y Gary P. Zank. "Impact of Magnetic Focusing on the Transport of Energetic Electrons in the Solar Corona". Journal of Physics: Conference Series 2544, n.º 1 (1 de julio de 2023): 012004. http://dx.doi.org/10.1088/1742-6596/2544/1/012004.

Texto completo

Resumen

Abstract Observations of Type III radio bursts discovered that electron beams with power-law energy spectra are commonly produced during solar flares. The locations of these electron beams are ~ 300 Mm above the particle acceleration region of the photosphere, and the velocities range from 3 to 10 times the local background electron thermal velocity. However, the mechanism that can commonly produce electron beams during the propagation of energetic electrons with power-law energy spectra in the corona remains unclear. In this paper, using kinetic transport theory, we find for the first time that the magnetic focusing effect governs the formation of electron beams over the observational desired distance in the corona. The magnetic focusing effect can sharply increase the bulk velocity of energetic electrons to the observed electron beam velocity within 0.4 solar radii (300 Mm) as they escape from the acceleration region and propagate upward along magnetic field lines. In more rapidly decreasing magnetic fields, energetic electrons with a harder power-law energy spectrum can generate a higher bulk velocity, producing type III radio bursts at a location much closer to the acceleration region. During propagation, the spectral index of the energetic electrons is unchanged.

Los estilos APA, Harvard, Vancouver, ISO, etc.

47

Noviadi, Satia Cahya, I. Wayan Sugiartha y Jauhar Fajrin. "Effect of Variations of Drilling Bolt Distances on Bending Strength of Composite Wood Beams". Journal of Science and Science Education 3, n.º 1 (24 de abril de 2022): 30–35. http://dx.doi.org/10.29303/jossed.v3i1.456.

Texto completo

Resumen

Wood products that are currently growing rapidly in many places in the world are laminated blocks (glulam). Laminate beam has many advantages in terms of size, strength and artistic. However, this laminated beam has a few drawbacks in terms of providing tools and materials for some areas. The laminated beam itself uses an adhesive material which is relatively expensive and requires a compression tool in its implementation. Therefore, an alternative is given in the form of composite beams. Composite beams that have developed so far use shear connectors in the form of bolts, nails, and pegs as the connecting tool. Meanwhile, shear connectors using drilling bolts have never been done. Therefore, based on this, it is necessary to research composite wood beams with an alternative, namely using drilling bolts as shear connectors in order to obtain the effect of variations in the distance of drilling bolts on the flexural strength of composite beams. The results of the flexural strength test obtained the strength of the composite beam with shear connectors with the largest distance of 3.125, followed by beams with shear connecting distances of 6.25 cm, 12.5 cm and 25 cm. This shows that the closer the shear connecting distance, the greater the strength obtained, with the percentage increase in variation of 31.5%, 38.737% and 46.072%, respectively.

Los estilos APA, Harvard, Vancouver, ISO, etc.

48

Bennett, M. A. "Quartz-spessartine metasediments (coticules) and their protoliths in North Wales". Geological Magazine 126, n.º 4 (julio de 1989): 435–42. http://dx.doi.org/10.1017/s0016756800006610.

Texto completo

Resumen

AbstractThin beds and small pods of quartz-spessartine metasediments (coticules) occur in pelites of the Gamlan Formation (Cambrian) of the Harlech Dome. The original microfabric of these sediments has been largely destroyed by recrystallization under low greenschist facies conditions. The quartz-spessartine pods occur throughout the pelites and appear to have formed by the metamorphism of diagenetic Mn-carbonate concretions. The thin beds of quartz-spessartine rock appear to have formed by the metamorphism of a protolith which was deposited rapidly and repeatedly over a wide area. Although there is no direct evidence of the nature of this protolith, the presence of altered Mn-carbonate-rich tuff beds in anchizonal mudstones of similar age in the St Tudwal's Peninsula suggests that the bedded quartz-spessartine rocks are, in fact, metamorphosed Mn-carbonate-rich tuff units. Both the bedded and podiform quartz-spessartine metasediments appear to have formed by reaction between clay minerals and Mn carbonates of earlier diagenetic origin.

Los estilos APA, Harvard, Vancouver, ISO, etc.

49

Sullivan, Clare, Thomas Hallaran, Gregory Sogorka y Kallie Weinkle. "An evaluation of conventional and subirrigated planters for urban agriculture: Supporting evidence". Renewable Agriculture and Food Systems 30, n.º 1 (25 de abril de 2014): 55–63. http://dx.doi.org/10.1017/s1742170514000131.

Texto completo

Resumen

AbstractAlthough interest in integrating agriculture into the urban landscape in the USA is increasing rapidly, there is a shortage of guidance for agricultural production in this context as well as a unique set of significant biophysical constraints. A common constraint is not being able to grow directly in the soil, making raised-bed gardening a necessity. Subirrigated planters (SIPs) are a style of raised bed with a subsoil reservoir that provides aeration and allows growers to irrigate below the soil where water is pulled up via capillary action. This bed design has vocal advocates; anecdotally, growers find them to be high yielding, water efficient and easier to maintain than standard raised beds. Given their apparent promise, there is interest in promoting SIPs and in utilizing them in larger-scale urban gardening operations but no rigorous tests compare these beds relative to standard raised beds. At one location and for one season, we compared yields for three crops: cayenne pepper (Capsicum annuum), sungold cherry tomatoes (Solanum lycopersicum) and lacinato kale (Brassica oleracea), crop quality and labor input for two styles of SIPs, as well as a sack garden, a variation of a SIP that does not require lightweight soil, with two conventional raised beds (one with a compost and topsoil mix and one with the soilless growing medium ideal for container gardening). Results from our first year of data indicate that both the SIP beds and the conventional beds with the soilless growing medium were more productive overall than conventional raised beds with topsoil and compost (P<0.01). Tomato production in the SIP without the root barrier was greater than both the conventional bed with the compost and topsoil mix (P<0.01) and the conventional bed with the soilless growing medium (P<0.05). The majority of the higher-cost beds had a positive revenue stream in the first summer season; given these results, investing in SIPs or in soil appropriate for raised beds appears to be worth the higher initial cost.

Los estilos APA, Harvard, Vancouver, ISO, etc.

50

Abdulhameed, Ali A. y Abdul Muttalib I. Said. "Systematic Design of Short-Span Segmental Beams Reinforced by CFRP Plates". Key Engineering Materials 857 (agosto de 2020): 130–37. http://dx.doi.org/10.4028/www.scientific.net/kem.857.130.

Texto completo

Resumen

The main objective of this study is to introduce a systematic design procedure for short-span segmental beams following a sophisticated ACI 440.2R-17 design procedure. The general aspects of innovative short-span segmental beams are easy to fabricate, economical and rapidly placed in pre-specified positions. Short-span segmental beams fabricated from individual precast plain-concrete blocks and CFRP plates. Recently, experimental tests performed on short-span segmental beams, by the authors, investigated CFRP plate-bonding, CFRP plate cross-sectional area, the thickness of plate-bonding epoxy resin, surface-to-surface condition of concrete blocks, as well as, interface condition of the bonding surface. The experimental program comprises testing of eight short-span segmental beams with an overall length, width and depth of (900, 200 and 80) mm, respectively, divided into four groups and subjected to 4-point bending test. The investigated test specimens exhibited considerable flexural strength under loading. Systematic designing of short-span segmental beams (SSSB) is presented in the current research. The advanced design method of SSSB with 1-layer of CFRP plates revealed an overestimation in ultimate strength by (73 and 15) % from the tested SSSB consisted of 1-layer CFRP/cementitious adhesive and SSSB has 1-layer CFRP/epoxy adhesive; respectively. Whereas the design method of SSSB with 2-layer of CFRP plates resulted in overestimation in strength by (71 and 45) % from the physical models of SSSB consisted of 2-layer CFRP/cementitious adhesive and SSSB has 2-layer CFRP /epoxy adhesive; respectively.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Artículos de revistas sobre el tema "BEMs rapides"

Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros