To see the other types of publications on this topic, follow the link: Catenary curve.
Journal articles on the topic 'Catenary curve'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Catenary curve.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Chan, T. O., and D. D. Lichti. "3D CATENARY CURVE FITTING FOR GEOMETRIC CALIBRATION." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XXXVIII-5/W12 (September 5, 2012): 259–64. http://dx.doi.org/10.5194/isprsarchives-xxxviii-5-w12-259-2011.
Full text
2
Battagel, Joanna M. "Individualized Catenary Curves: Their Relationship to Arch Form and Perimeter." British Journal of Orthodontics 23, no. 1 (1996): 21–28. http://dx.doi.org/10.1179/bjo.23.1.21.
Full textAbstract:
Study casts of the lower arches of 35 children in whom arch alignment was considered acceptable, were examined using a reflex microscope. Arch perimeter was calculated mathematically from a method which required measurement of the mesio-distal widths of the teeth only. This was described as the ‘overlap’ method. Arch perimeter was also calculated using individualized catenary curves for each subject. Two calculations were made, recording arch width either at the distal contact points of the first permanent molars or between their mesio-buccal cusps. Arch perimeter measured from the length of the catenary curves was consistently shorter than that calculted by the overlap method. The variation ranged from 0·02 to 4·58 mm. The catenary constructed using the distal molar contacts gave a better representation of the actual arch form: the mean discrepancy was 2·36 mm, compared with 2·86 mm with the second method where arch width was measured between mesio-buccal cusps. Both techniques for calculation of arch perimeter were heghly reproducible. The catenary curve only approximated arch form well when the arch was relatively narrow across the inter canine region. For square arches this method was unsatisfactory. It is suggested that alternative techniques would be more reliable and the overlap method desribed here is considered satisfactory.
3
Yi, Lingzhi, You Guo, Nian Liu, Jian Zhao, Wang Li, and Junyong Sun. "Health status identification of catenary based on VMD and FA-ELM." Journal of Algorithms & Computational Technology 15 (January 2021): 174830262110248. http://dx.doi.org/10.1177/17483026211024898.
Full textAbstract:
Catenary works as a key part in the electric railway traction power supply system, which is exposed outdoors for a long time and the failure rate is very high. Once a failure occurs, it will directly affect the driving safety. Based on the above, a model of identifying the health status for the catenary based on firefly algorithm optimized extreme learning machine combined with variational mode decomposition is proposed in this paper. Variational mode decomposition is used to decompose the original detection curve of catenary into a series of intrinsic mode function components, and the intrinsic mode function components filtered by the correlation coefficient method after decomposing each detection curve are input into the firefly algorithm optimized extreme learning machine model to realize health status identification. Compared with some other models, the results show that the proposed model has better health status identification effect.
4
Ren, Xiang. "Analytic Methods of Main Cable Initial Curve Calculation in Variable Temperature Field." Advanced Materials Research 163-167 (December 2010): 307–12. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.307.
Full textAbstract:
In order to study temperature effect on initial curve of main cable, three different temperature models were built about temperature changes of main cable along span direction, and iteration calculation methods to find initial curve of main cable in variable temperature field was proposed based on the theory that the length of non-stress wire strand is persistence in unloaded cable station and construction completion station. The catenary equation in variable temperature field was deduced and the suspender length variation as well as horizontal component of cable forces were calculated based on the catenary equation. Taking some suspension bridge for an example, suspender length variation, horizontal component of the cable forces and node coordinate under three different temperature models were calculated by iteration calculation methods.
5
Wei, Wenfu, Chongliang Liang, Zefeng Yang, et al. "A novel method for detecting the pantograph–catenary arc based on the arc sound characteristics." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 233, no. 5 (2018): 506–15. http://dx.doi.org/10.1177/0954409718799792.
Full textAbstract:
In recent years, the speed and the current transmission density of high-speed railways are increased. As a result, the rate of the occurrence of pantograph–catenary arc also increases, which directly influences the service performance of the pantograph–catenary system. The detection and identification of the pantograph–catenary arc is of great significance for evaluating the off-line level to ensure the safe operation of the pantograph–catenary system. The currently used conventional optical arc detection method would be distorted by strong sunlight or other environmental lights in the actual operation, which would affect the accuracy of detection. On the contrary, the arc sound signal is not affected by the diurnal variation and can be easily obtained; it can also be distinguished well from other interfering sounds. In this paper, a new method that uses the arc sound is proposed to realize the effective detection of the pantograph–catenary arc. The frequency spectrum and the intensity characteristics of the pantograph–catenary arc sound are analyzed. The results show that the frequency band of the arc sound signal is wide and mainly gets distributed at 5–17 kHz. The curve of the sound waveform is drawn by calculating the short-time average energy, which is used to obtain the arc’s starting time, duration, and intensity, for calculating the off-line rate.
6
Wu, Shuang. "FANUC CNC Lathe System Based on Macro Processing of Special Curves." Applied Mechanics and Materials 716-717 (December 2014): 717–19. http://dx.doi.org/10.4028/www.scientific.net/amm.716-717.717.
Full textAbstract:
Based on FANUC nc lathe catenary macro program, explores the rule curve macro program compiling method, using a simple example is given to illustrate the macro program programming method, the workpiece coordinate origin is not Z zero programming method, the continuous processing same shape graphics macro programming method, provides the programming method of the other special rule curve and reference .
7
Pu, Mingbo, Xiong Li, Xiaoliang Ma, et al. "Catenary optics for achromatic generation of perfect optical angular momentum." Science Advances 1, no. 9 (2015): e1500396. http://dx.doi.org/10.1126/sciadv.1500396.
Full textAbstract:
The catenary is the curve that a free-hanging chain assumes under its own weight, and thought to be a “true mathematical and mechanical form” in architecture by Robert Hooke in the 1670s, with nevertheless no significant phenomena observed in optics. We show that the optical catenary can serve as a unique building block of metasurfaces to produce continuous and linear phase shift covering [0, 2π], a mission that is extremely difficult if not impossible for state-of-the-art technology. Via catenary arrays, planar optical devices are designed and experimentally characterized to generate various kinds of beams carrying orbital angular momentum (OAM). These devices can operate in an ultra-broadband spectrum because the anisotropic modes associated with the spin-orbit interaction are almost independent of the incident light frequency. By combining the optical and topological characteristics, our approach would allow the complete control of photons within a single nanometric layer.
8
Wiśniowski, Rafał, Paweł Łopata, and Grzegorz Orłowicz. "Numerical Methods for Optimization of the Horizontal Directional Drilling (HDD) Well Path Trajectory." Energies 13, no. 15 (2020): 3806. http://dx.doi.org/10.3390/en13153806.
Full textAbstract:
Advances in the field of material engineering, computerization, automation, and equipment miniaturization enable modernization of the existing technologies and development of new solutions for construction, inspection, and renovation of underground pipelines. Underground pipe installations are used in the energy sector, gas industry, telecommunications, water and sewage transport, heating, chemical industry, and environmental engineering. In order to build new pipeline networks, dig and no-dig techniques are used. Horizontal Directional Drilling (HDD) is one of the most popular trenchless technologies. The effectiveness of HDD technology application is mostly determined by its properly designed trajectory. Drilling failures and complications, which often accompany the application of the HDD technology, result from poor design of the well path in relation to the existing geological and drilling conditions. The article presented two concepts of Horizontal Directional Drilling well path trajectory design: Classic sectional, which is a combination of straight and curvilinear sections, and a single-section chain curve trajectory (catenary). Taking into account the advantages and disadvantages of the catenary trajectory relative to the sectional trajectory, the author’s solution was presented, which was the implementation of the sectional trajectory with a maximum shape similarity to the catenary trajectory. The new approach allowed us to take advantage of a chain curve trajectory and was easier to implement using the available technology. The least squares method, based on deviations from a catenary trajectory, was set as the matching criterion. The process of searching for a trajectory, being a combination of straight and curvilinear sections as similar as possible to a catenary-type trajectory, was carried out using two methodologies: State space search and a genetic algorithm. The article shows the pros and cons of both optimization methodologies. Taking into account the technical and technological limitations of HDD drilling devices, a new approach was proposed, combining the methodology of state space search with the genetic algorithm. A calculation example showed the application of the proposed methodology in an engineering design process.
9
Yong, Hu, Du Yuxin, Cao Yong, et al. "Research on Mathematical Model for Non-Uniformly Qualitative Suspension Cable." MATEC Web of Conferences 175 (2018): 03039. http://dx.doi.org/10.1051/matecconf/201817503039.
Full textAbstract:
Catenary theory is recognized as the most effective suspension theory which can reflect the real situation of suspension. Catenary equation belongs to transcendental function, so there are some difficulties in calculation and application. Parabola theory, suspension curve theory and perturbation method are gradually formed as the theoretical basis for the study of suspension cables. This paper takes the 500m spherical radio telescope project as the background. The modeling method of suspension cable under multiple concentrated loads is analyzed, and the mathematical model of supporting cable after load is derived. The research in this paper provides a reference for the establishment of mathematical model of suspension cable in practice.
10
Jwa, Yoonseok, and Gunho Sohn. "A Piecewise Catenary Curve Model Growing for 3D Power Line Reconstruction." Photogrammetric Engineering & Remote Sensing 78, no. 12 (2012): 1227–40. http://dx.doi.org/10.14358/pers.78.11.1227.
Full text
11
Liu, Xi Jun, Er Hui Zhang, and Su Xia Zhang. "Comparative Research on Different Combination of the Rain-Wind Induced Vibration Models." Applied Mechanics and Materials 90-93 (September 2011): 1005–9. http://dx.doi.org/10.4028/www.scientific.net/amm.90-93.1005.
Full textAbstract:
In this paper, the comparative study of RWIV will be proceeding. Aim at the model of rivulet, a kind of sine function is accepted, and another kind of rivulet model is established on the basis of analysis on the stress of the rivulet. Aim at the model of cable’s initial curve under gravity, a kind of parabolic function is accepted, and another kind of model accepted as a catenary. Then, solve the equations of cable and the rivulet jointly by numerical method, get the characteristics of motion of the cable and rivulet, then investigate the factors which is related with the model. The influence of the different model of cable is very little when the rivulet model is assumed as a sine function. However, the influence of the different model of cable is large when the rivulet model is established on the basis of analysis on the stress. Then discover the catenary cable with moving rivulet is more rational with the field observation.
12
Król, Krzysztof, Krzysztof Budnik, and Piotr Jarek. "Calculation of magnetic field intensity under power line with taking into account conductor sag." ITM Web of Conferences 19 (2018): 01013. http://dx.doi.org/10.1051/itmconf/20181901013.
Full textAbstract:
The paper presents a calculation method of the magnetic field under an overhead power line taking into account conductor sag, which is described by the catenary curve. The calculations take into account the variability of the charge distribution along the conductor and wire sag for the eclectic field, while the calculation of intensity of the magnetic field take into account the impact of induced currents in the wires of lightning. The simulation results were compared with results measurements.
13
Mimaki, Toshitaro, Toshiro Aso, Yuhjih Eguchi, and Masaaki Mizumura. "Evaluation of drag minimum for catenary curve using approximatecatenary trajectory and equivalent build up section." Journal of the Japanese Association for Petroleum Technology 65, no. 3 (2000): 247–56. http://dx.doi.org/10.3720/japt.65.247.
Full text
14
Jing, Tian Hu, and Qing Ning Li. "Effects Analysis of Bending Stiffness of Cables on Stress Distribution and Curve Shape in Super-Long Single Suspension Cable Structures." Advanced Materials Research 163-167 (December 2010): 173–76. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.173.
Full textAbstract:
The design scheme of a suspension bridge with a super-long-span of 3300 m was taken as an example, and calculating results from 3 mechanics models are compared with each other to study the effects of bending stiffness of cables on stress distribution and curve shape in super-long single suspension cable structures on the basis of the Finite Element Method (FEM) algorithm of ANSYS and the analytical segmental catenary method for cables’ shape-finding. The study shows that the influence of bending stiffness on curve shape-finding of cables is negligible; Although its effects on stress distribution in cross sections of main cables due to dead loads is small, the error of horizontal forces probably results in great one for the calculation of bending moments at the bottom cross-sections of bridge pylons, which needs attention to ensure the structural safety.
15
Li, Zhou, Yuan Cheng Wei, Rong Hui Wang, Jia Lun Li, and Peng Zhang. "Application of Exact Element-Method on Calculation of Form-Finding and Unstressed Length of Cable." Applied Mechanics and Materials 405-408 (September 2013): 1699–708. http://dx.doi.org/10.4028/www.scientific.net/amm.405-408.1699.
Full textAbstract:
The problem of form-finding for the suspended cable is actually the problem of determining all key points coordinates on main cable, which are by equilibrium relation on the horizontal force, main cable sagitta and lifting point force under the precondition of determining the endpoints boundary conditions of cable segment. According from the static equilibrium relationship of cable element, based on the analysis of its analytical solution process, in this paper, the cable elements are divided into two types in accordance withthe vertical distribution load along the arc length and along the string length , the corresponding shape curve of cable element is the parabola and the catenary, and with parabolic results as its initial value for the iteration of nonlinear solution, then cable element eventually converge for the catenary. And based on the exact coordinates results ,the calculation method of the length without stress is presented,and compiled corresponding computational procedures. By comparing the results of form-finding and the cable-length in non-stress according to program compiled and the results from the finite element software and the measured value of Aizhai suspension bridge, compared with the nonlinear finite element method,it confirmed the method requireing smaller dividing element density, the convergence speed is quicker and the results can ensure the precision.
16
Yang, N., D.-S. Jeng, and X. L. Zhou. "Tension Analysis of Submarine Cables during Laying Operations." Open Civil Engineering Journal 7, no. 1 (2013): 282–91. http://dx.doi.org/10.2174/1874149520131130009.
Full textAbstract:
This paper presents a semi-analytical approximation for a two-dimensional (2D) tension analysis of submarine cables during laying operations. In the analysis, based on geometric compatibility relations and equilibrium equations, a set of non-linear differential equations are obtained. The present model considers effects of ocean currents, cable ship motion, pay-out rate, water depth and material properties on submarine cable behavior in water, which are crucial during laying operations. As shown in numerical examples, with consideration of currents and cable ship motion, the cable tension appears to be smaller and cable configuration curve tends to be fatter than the conventional catenary theory.
17
Austin, L., and Mathew Burley. "Theoretical Modeling of Wire Dynamics and Failure Modes During Manufacture on a Double Twist Machine." Journal of Mechanical Design 125, no. 1 (2003): 150–57. http://dx.doi.org/10.1115/1.1539511.
Full textAbstract:
The problem of wire ballooning, or wire breakage, due to force imbalance is common during the production of wire on double twist machines. This paper examines the forces in wire during the bunching or twinning process. The bow shape is simplified to represent the arc of a circle for mathematical simplicity, which also allows the work to be related to any size of double twist machine produced by any manufacturer, with the proviso that a catenary curve forms the basis of the bow shape. Mathematical approximations of the level of force imbalance between the pre-tension and take-up tension during production are made, and the location of wire breakage within the bow is predicted.
18
Niu, Hong Bo, Hong Shan Zhao, and Ji Fei Cao. "Application and Cognition of Unconventional Horizontal Well Drilling Technology in Shengli Oilfield." Applied Mechanics and Materials 318 (May 2013): 513–18. http://dx.doi.org/10.4028/www.scientific.net/amm.318.513.
Full textAbstract:
Long Horizontal Section Well has been an important way to explore deficient oil/gas field. Relative drilling technology has developed rapidly in recent years in China. This article puts focus on the methodology of well plan, trajectory control and matched tools and application situation of drilling fluid and drilling equipment for long horizontal section well. Based on the analysis of drilling and completion technical difficulties, suitability of some well design methods such as catenary curve used to decline friction and torque have been discussed, and even more practical means proven in many designs have been recommended. After introducing the drilling capability of the long horizontal-section well, the article indicated some special characteristic of the horizontal section wells and difference from ERD wells. Consequently, some advice is given on the definition and development of the drilling technology of long horizontal section wells.
19
Liu, Xin, Wei Ren, Qiang Zhang, and Shu Hao Zhang. "Research of Marine Simulator Cables' Mathematical Models." Advanced Materials Research 889-890 (February 2014): 551–54. http://dx.doi.org/10.4028/www.scientific.net/amr.889-890.551.
Full textAbstract:
As ships gradually getting larger, more special, tug assisted operation of the ship in and out of Port , berthing and unberthing becomes increasingly prominent, Tug-related training and safety assessment is increasingly important, increasing the tug unit for marine simulator is urgent.In tug unit, the cable is an important part, to establish the mathematical model of cable is key. Mooring strain satisfy Hooke's law, using the catenary equation and Hooke's Law deduces mooring unstressed length formula, according to the Department to calculate the cable unstressed length and the corresponding relations of the actual length of the mooring to calculate the tension of the mooring; Otherwise, ignoring the weight of the mooring by mooring strain curve fitting polynomial to calculate the tension of the mooring, and calculated the level of tension and vertical tension of the mooring. calculating example to verify the correctness and practicability of the model.
20
KUNO, Atsushi, Satoko ABIKO, Shota NARASAKI, et al. "2A2-F01 Manipulation of a Deformable Linear Object by an Unmanned Aerial Vehicle Based on Shape Estimation Using Catenary Curve." Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) 2015 (2015): _2A2—F01_1—_2A2—F01_4. http://dx.doi.org/10.1299/jsmermd.2015._2a2-f01_1.
Full text
21
Zhu, Bo, Weiping Huang, Xinglong Yao, Juan Liu, and Xiaoyan Fu. "Influences of the Load of Suspension Point in the z Direction and Rigid Body Oscillation on Steel Catenary Riser Displacement and Frequency Under Wave Action." Energies 12, no. 2 (2019): 273. http://dx.doi.org/10.3390/en12020273.
Full textAbstract:
The rigid body swing is an important problem for steel catenary risers (SCRs). In addition to many other important issues, the transverse flow direction response is studied in this paper. By extending the load terms of the large deflection slender beam equation, the load of suspension point in the z direction, Morison and rigid body swing are superimposed on the beam equation. On the basis of the above work, a Cable3d subroutine is written to complete the task. Then the structural response is simulated and verified by the Lissajous phenomenon and spectral phase analysis. On the basis of verification, the response is analyzed from an angle of three-dimensional space and the influence coefficient is adopted to evaluate the effect of rigid body swing. The importance of loads is determined by spectral analysis. Phase curve and the change of vibration direction are analyzed by higher orders of frequency. The results show the verification of Lissajous and spectral phase analysis are feasible. The analysis of the spatial response shows the vibration direction of the 140th node is in the same direction as the rigid body swing vector, so the interaction is relatively of more intensity and the influence coefficient is relatively larger. This influence interval of rigid body swing displacement statistical analysis is −0.02 to 0.02 and the effect is weak. The spectrum analysis indicates there is no resonance between the main load and the bending vibration, and the analysis also shows the main influence load of the transverse flow response in this paper is the top load in the z direction. According to phase analysis, the load has a high order effect on the spectral phase curve of the structure. This paper has drawn a conclusion that rigid body swing has limited effect on transverse flow response, however, it has a relatively strong impact on the middle region of the riser, so it plays an influential role on the safety of the riser to some extent. The key point for this paper is to provide qualitative standards for the verification of rigid body swing through Lissajous graphs, which are central factors to promote the development of rigid body swing. It is hoped that the above research can provide some reasonable suggestions for the transverse flow response simulation of the steel catenary riser.
22
Kai, Yan, Zhang Yao, Cai Hao, Fan Lili, and Xin Zhang. "Postfire Safety Investigation on Prestressed RPC Beams after Exposure to Elevated Temperatures." Advances in Materials Science and Engineering 2020 (May 8, 2020): 1–14. http://dx.doi.org/10.1155/2020/7837418.
Full textAbstract:
Since the postfire safety of prestressed RPC beams after exposure to elevated temperatures needs to be studied and proved, this paper prepares eight smart prestressed RPC beams with intelligent sensors built in to monitor the internal temperature, force, and strain. The residual bearing tests after fire are carried out. The failure process of the beams under static load with different fire durations cover thickness of tendons, load ratio, bonded and unbonded tendons, and partial prestressing ratio, which are investigated. The load-deflection curves, crack distributions and developments, and strain variations are obtained, in addition to the damage mechanism and failure mode of the beams. The results show that the load-deflection curve of the prestressed RPC beam after fire has obviously three polylines, and the deflection points are where the cracks expand and the tendons yield. The failure procedure is the same as that of under-reinforced beams, while the height of the crushing zone is much lower than that of the balanced-reinforced beam at room temperature. The whole span deformation demonstrates a strong catenary effect, and the midspan deflection is approximately 1/40 of the effective span. The postfire safety of the bonded prestressed RPC beams is superior to that of unbonded prestressed RPC beams. The test results of this paper provide a basis for the safety performance evaluation and control of prestressed RPC beams after fire.
23
Chau, Nguyen Phong. "Linear n-compartment catenary models: Formulas to describe tracer amount in any compartment and identification of parameters from a concentration-time curve." Mathematical Biosciences 76, no. 2 (1985): 185–206. http://dx.doi.org/10.1016/0025-5564(85)90004-5.
Full text
24
Yu, Qiong, Zhou Dao Lu, Jiang Tao Yu, Xing Zhuang Zhao, and Jin Dai. "Experimental Study on Specimens of Steel Secondary Beam Embedded in Reinforced Concrete Girder of Frame Structure." Advanced Materials Research 243-249 (May 2011): 1072–84. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.1072.
Full textAbstract:
Test of two specimens (four different joints) of steel secondary beam embedded in reinforced concrete girder in frame structure and one specimen with steel cantilever beam embedded in reinforced concrete girder under static load were conducted. The steel beam up-flange was pulled out because of the concrete cracks caused by the moment, shear and torsion at the upper zone of the concrete beam near the steel beam end. Shear failure of the concrete beam and the top flange pullout failure are the most hazardous failure modes. Lacking restraint of concrete and the reinforcement of steel bar in the concrete slab and catenary action of restraint steel beam, the capacity of steel cantilever beam is much smaller than other beams. Load-slip curve of top flange of steel beam, load-rotation curve of the steel beam end are obtained through experiment. Primary calculation method of joints flexural capacity related to section size of composite steel beam, embedded depth of steel beam, flange width of steel beam embedded end, height of frame girder, is put up with. Analytical results of ABAQUS are shown as follows. Top flange pullout failure of steel beam is caused by the detachment of concrete and steel beam end, and the warp of the concrete slab near the support plays an unfavorable action on the performance of the steel beam. The end rotational angle of the steel beam with anchor bar is smaller than that without. The steel beam with shear connectors develops a smaller rotational angle and a higher load capacity.
25
Azevedo, Fábio, André Dias, José Almeida, et al. "LiDAR-Based Real-Time Detection and Modeling of Power Lines for Unmanned Aerial Vehicles." Sensors 19, no. 8 (2019): 1812. http://dx.doi.org/10.3390/s19081812.
Full textAbstract:
The effective monitoring and maintenance of power lines are becoming increasingly important due to a global growing dependence on electricity. The costs and risks associated with the traditional foot patrol and helicopter-based inspections can be reduced by using UAVs with the appropriate sensors. However, this implies developing algorithms to make the power line inspection process reliable and autonomous. In order to overcome the limitations of visual methods in the presence of poor light and noisy backgrounds, we propose to address the problem of power line detection and modeling based on LiDAR. The PL 2 DM, Power Line LiDAR-based Detection and Modeling, is a novel approach to detect power lines. Its basis is a scan-by-scan adaptive neighbor minimalist comparison for all the points in a point cloud. The power line final model is obtained by matching and grouping several line segments, using their collinearity properties. Horizontally, the power lines are modeled as a straight line, and vertically as a catenary curve. Using a real dataset, the algorithm showed promising results both in terms of outputs and processing time, adding real-time object-based perception capabilities for other layers of processing.
26
Heyman, J. "Hooke's cubico–parabolical conoid." Notes and Records of the Royal Society of London 52, no. 1 (1998): 39–50. http://dx.doi.org/10.1098/rsnr.1998.0033.
Full textAbstract:
In 1675 Robert Hooke published, as one of his ‘Inventions’, a Latin anagram concerning the ‘true...form of all manner of arches for building’. His discovery was that the shape of a light flexible cord subjected to specified loads would, when inverted, give the required shape of the perfect (masonry) arch to carry those same loads. Hooke knew that the catenary curve was not given by the parabola y = ax 2 , but he was unable to solve the problem mathematically, and the decipherment of the anagram was not published until after his death. Four years earlier Hooke had stated to the Royal Society that the solution to the corresponding three–dimensional problem, that of the shape of the perfect dome, was the cubico–parabolical conoid; that is, the dome was formed by rotating the cubic parabola y = ax 3 about the y –axis. It is shown that the correct form of dome may be evaluated in terms of the integrals erf( t ) and erg( t ). Moreover, an alternative solution as a power series is rapidly convergent, and has a leading term in x 3 followed by a much smaller term in x 7 . Wren's design for the dome of St Paul's Cathedral made use of the idea of Hooke's ‘hanging chain’.
27
Li, Tianxing, Xiaotao An, Xiaozhong Deng, Jinfan Li, and Yulong Li. "A New Tooth Profile Modification Method of Cycloidal Gears in Precision Reducers for Robots." Applied Sciences 10, no. 4 (2020): 1266. http://dx.doi.org/10.3390/app10041266.
Full textAbstract:
The tooth profile modification of cycloidal gears is important in the design and manufacture of precision reducers or rotary vector (RV) reducers for robots. The traditional modification design of cycloidal gears is mainly realized by setting various machining parameters, such as the size and center position of the grinding wheel. The traditional modification design has some disadvantages such as complex modification calculation, uncontrollable tooth profile curve shape and unstable meshing performance. Therefore, a new tooth profile modification method is proposed based on the consideration of the comprehensive influences of pressure angle distribution, meshing backlash, tooth tip and root clearance. Taking the pressure angle and modifications of tooth profile as the parameters of the modification function and the meshing backlash of gear teeth as constraints, the mathematical model for tooth profile modifications is built. The modifications are superimposed on the normal direction of the theoretical profile—the force transmission direction. The mathematical relationship between the modifications and the pressure angle distribution, which determines the force transmission performance, is established. Taking the straight line method, cycloid method and catenary method as examples, by means of the tooth contact analysis technology, the transmission error and minimum meshing backlash, which reflects the lost motion, of the newly modified profile are analyzed and verified. This proposed method can flexibly control the shape change of the modification profile and accurately pre-control the transmission accuracy of the cycloid-pin gear. It avoids the disadvantages of traditional modification methods, such as uncontrollable tooth profile shape and unstable meshing accuracy. The method allows good meshing characteristics, high force transmission performance and more precise tooth profile curve. The study provides a new design method of the modified profile of cycloidal gears.
28
Liu, Meilin, Xiangsheng Chen, Zhenzhong Hu та Shuya Liu. "Active Earth Pressure of Limited C-φ Soil Based on Improved Soil Arching Effect". Applied Sciences 10, № 9 (2020): 3243. http://dx.doi.org/10.3390/app10093243.
Full textAbstract:
For c-φ soil formation (cohesive soil) of limited width with ground surface overload behind a deep retaining structure, a modified active earth pressure calculation model is established in this study. And three key issues are addressed through improved soil arching effect. First, the soil-wall interaction mechanism is determined by considering the soil arching effect. The slip surface of a limited soil is proved to be a double-fold line passing through the retaining wall toe and intersecting the side wall of the existing underground structure until it reaches the ground surface along the existing side wall. Second, the limited width boundary is explicated. And third, the variation in the active earth pressure from parameters of limited c-φ soil is determined. The lateral active earth pressure coefficient is nonlinear distributed based on the improved soil arching effect of the symmetric catenary curve. Furthermore, the active earth pressure distribution, the tension crack at the top of the retaining wall and the resultant force and its action point were obtained. By comparing with the existing analytical methods, such as the Rankine method, it demonstrates that the model proposed in this study is much closer to the measured and numerical results. Ignoring the influence of soil cohesion and the limited width will exponentially reduce the overall stability of the retaining structure and increase the risk of accidents.
29
TAKEDA, Koutarou, and Motoji YAMAMOTO. "2A1-I01 Modeling of a Large Scale Parallel Wire Mechanism Using Catenary Curve and Dynamics of Suspended Object for Motion Analysis(Mechanism and Control for Wire Actuation System)." Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) 2011 (2011): _2A1—I01_1—_2A1—I01_4. http://dx.doi.org/10.1299/jsmermd.2011._2a1-i01_1.
Full text
30
Ruta, P., and M. Meissner. "Analysis of the Spatial Vibration of Nonprismatic Arches by Means of Recurrence Relations for the Coefficients of the Chebyshev Series Expansion of the Solution." Mathematical Problems in Engineering 2018 (December 31, 2018): 1–27. http://dx.doi.org/10.1155/2018/1512825.
Full textAbstract:
The problem of spatial vibrations, both aperiodically forced and free vibrations, of an arch with an arbitrary distribution of material and geometric parameters is considered. Approximation with Chebyshev series was used to solve a conjugated system of partial differential equations describing the problem. The system of differential equations was solved using an algorithm generating a recursive infinite system of equations, developed by S. Paszkowski in “Numerical applications of Chebyshev polynomials” (in Polish), Warsaw PWN, 1975. Since the coefficients of the obtained system of equations are defined by closed analytical formulas they can be directly used to solve any nonprismatic arch, without it being necessary to solve again the considered problem. The algorithm is highly accurate; i.e., already at a small approximation base it yields results agreeing with exact analytical solutions (obviously for problems in the case of which such solutions can be derived). In order to demonstrate this the eigenfrequencies and eigenvectors obtained for a circular prismatic arch were compared with their precise values determined from the exact analytical solutions. The results yielded by the proposed method were also compared with the results obtained by other methods and by other authors. As an illustration, the proposed method was used to solve a more complex problem, i.e., the problem of the free and aperiodically forced vibrations of a nonprismatic arch with its axis described by a catenary curve. In the example the effect of the lack of cross-sectional symmetry of the arch on the form of the system’s spatial free and forced vibrations was analysed.
31
Shevchenko, Natalya, Anatoly Soshinov, Olga Elfimova, Julia Lebedeva, and Olga Akhmedova. "Improving the energy efficiency of wide crossings of overhead power lines." E3S Web of Conferences 178 (2020): 01046. http://dx.doi.org/10.1051/e3sconf/202017801046.
Full textAbstract:
The use of new generation wires in the design of wide spans of overhead power lines over water barriers and large gorges can increase their transmission capacity and increase reliability. However, when large currents flow, load losses in line also increase. Thus, it is necessary to obtain a methodology for technical and economic comparison of design options for overhead power lines over large crossings, which enables to determine the most cost-effective version of the project with high mechanical reliability. For comparative analysis, five options for wide spans of overhead power lines over the river with new-generation wires of Russian production were compiled: Aluminium Alloy Conductor Steel Reinforced, Z-type (high conductivity), Thermal-Resistant Conductor, Aluminium Compozite Core Conductor, ASk2y. Option with Aluminium Conductor Steel Reinforced wire was taken as the source. For the first option, the crossing scheme E-A-A-E was selected, for the remaining options E-I-I-E scheme was considered. For the modes of maximum loads, minimum temperature and average annual conditions, the mechanical calculation of wires was carried out using the method of permissible stresses. The wire bending deflections were determined in accordance with the theory of the catenary curve. The method of integrated indicators was used to perform a technical and economic comparison of these options. The calculation results showed that among the proposed options, the most optimal is a crossing with the ACCC wire having minimum relative investment per 1 MW of transmitted electricity and minimal power loss. The transmission capacity of the line with this wire is increased by 1.8 times, and the cost of crossing is reduced by 16%. Due to the compact design of wire, the probability of ice formation on wire is reduced, and the reduced bending deflection reduces the probability of wire break due to natural environmental influences.
32
Bont, Leo Gallus, Laura Ramstein, Janine Schweier, and Hans Heinimann. "A QGIS Based Workflow for Optimized Cable Road Layout Planning." Environmental Sciences Proceedings 3, no. 1 (2020): 103. http://dx.doi.org/10.3390/iecf2020-07768.
Full textAbstract:
Cable-based technologies have been a backbone for harvesting on steep slopes. The planning of a cable road is a complex task. It essentially comprises the definition of the start and end points of a cable road, as well as the intermediate supports. It must be ensured that the permissible forces (in particular, skyline tensile forces) are not exceeded, that there is a sufficient clearance between the load path and the ground, that suitable anchor trees are found, and that at the same time the number of intermediate supports is minimized as far as possible. On the other hand, for ergonomic and silvicultural reasons (work safety, damages to the forest), the skyline should be as high as possible. In practice, the search for a solution is often iterative; especially with long lines, several attempts may be necessary until a good line is found. The presented QGIS (free and open-source cross-platform desktop geographic information system) plugin searches automatically for the optimal cable road layout, so the planning process can be considerably simplified and obtained solutions are more cost-efficient. The plugin is designed for Central European conditions and assumes a standing skyline (fixed anchored skyline at both ends). For the calculation of the mechanical properties of the skyline, a close to catenary method is used (Zweifel 1960). When testing the feasibility of the cable line, care is taken that (1) the maximum permissible stresses in the skyline are not exceeded, (2) there is a minimum distance between the load path and the ground, and (3) when using a gravitational system, there is a minimum inclination in the load path. The newly developed method calculates the load path curve and the forces occurring in it more accurately than other tools available on the market. We further present a method to identify potential support and anchor trees directly from remote sensing data, which we aim to integrate in a further plugin. This ensures that there are effectively trees at the proposed intermediate positions and that the solution can be implemented in practice.
33
Wang, Tian Ying, Li Jun Yang, Zhi Gang Xu, and Jin Kun Liu. "Design and Comparison of Catenary and Taut Mooring Systems for New Concept FPSO IQFP in Shallow Waters." Applied Mechanics and Materials 353-356 (August 2013): 2670–75. http://dx.doi.org/10.4028/www.scientific.net/amm.353-356.2670.
Full textAbstract:
In order to design an effective and economical multi-point mooring system for the new concept FPSO IQFP (fillet inverted quadrangular frustum pyramid shaped FPSO, presented by the lead author), the effects of the mooring parameters on the performance of catenary mooring system and taut mooring system were investigated according to the initial design plans given in advance according to the steady environment forces and practical experiences. Then, the optimal mooring systems were developed on the basis of the static analysis results combined with the coupled calculations in time domain. Finally, the merits and demerits of the two mooring schemes were compared based on the mooring and static characteristic parameters as well as the curves of restoring force against horizontal displacement of the catenary and taut mooring systems respectively. The results verify that the taut mooring system is preferable to the catenary mooring system for IQFP deployed in shallow waters.
34
Peng, Xia, Xian-Sheng Gong, and Jin-Jun Liu. "The study on crossover layouts of multi-layer winding grooves in deep mine hoists based on transverse vibration characteristics of catenary rope." Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 233, no. 2 (2018): 118–32. http://dx.doi.org/10.1177/0959651818785309.
Full textAbstract:
In a deep mine winding hoist system, the lateral oscillation of the catenary rope is an important evaluation index of orderly rope arrangement and engineering safety. Different boundary excitations will appear when the wire rope winds on symmetrical or asymmetrical grooves, which results in the different dynamic responses of the hoisting system. In this article, the vibration equations of a deep mine hoisting system are established by using the Hamilton principle, and excitation functions of different crossover zone layouts are deduced. The operation curves are introduced to conduct the experiment based on a certain experimental platform. The lateral oscillation of the catenary rope is recorded by high-speed cameras, and an effective image processing method is proposed to obtain the vibration response of a certain point in the catenary rope. The numerical simulations are compared with the experimental results to prove the vibration models derived in this article are valid. The models could provide reliable basis for the grooves type selection in deep mine hoisting.
35
Antunes, Pedro, Jorge Ambrósio, João Pombo, and Alan Facchinetti. "A new methodology to study the pantograph–catenary dynamics in curved railway tracks." Vehicle System Dynamics 58, no. 3 (2019): 425–52. http://dx.doi.org/10.1080/00423114.2019.1583348.
Full text
36
Hatibovic, Alen. "Derivation of Equations for Conductor and Sag Curves of an Overhead Line Based on a Given Catenary Constant." Periodica Polytechnica Electrical Engineering 58, no. 1 (2014): 23. http://dx.doi.org/10.3311/ppee.6993.
Full text
37
Jokela, Eric J., Steven B. Jack, and Christopher A. Nowak. "Site Index Curves for Unthinned Norway Spruce Plantations in New York." Northern Journal of Applied Forestry 5, no. 4 (1988): 251–54. http://dx.doi.org/10.1093/njaf/5.4.251.
Full textAbstract:
Abstract Polymorphic site index curves were developed for Norway spruce growing in unthinned, old-field plantations in the Allegheny Plateau region of central New York (reference age is 50 years at breast height). Stem analysis data were collected from 151 dominant and codominant trees representing a single but wide-spread soil catena (Bath - Lordstown - Mardin - Volusia; approx. 2.7 million ac). Site index curves at 10-ft intervals for breast height ages 10 to 50 years are furnished for field estimation. For more precise estimates, a table of site index values by 2-ft heights and 2-year ages is provided. North. J. Appl. For. 5:251-254, December 1988.
38
TAKEDA, Koutarou, and Motoji YAMAMOTO. "G12 Modeling of a Large Scale Parallel Wire Mechanism Using Catenary's Curve for the Motion Analysis." Proceedings of Conference of Kyushu Branch 2011.64 (2011): 237–38. http://dx.doi.org/10.1299/jsmekyushu.2011.64.237.
Full text
39
Cortina, João P. R., Fernando J. M. de Sousa, and Luis V. S. Sagrilo. "Neural Networks Applied to the Wave-Induced Fatigue Analysis of Steel Risers." Mathematical Problems in Engineering 2018 (July 25, 2018): 1–16. http://dx.doi.org/10.1155/2018/2719682.
Full textAbstract:
Time domain stochastic wave dynamic analyses of offshore structures are computationally expensive. Considering the wave-induced fatigue assessment for such structures, the combination of many environmental loading cases and the need of long time-series responses make the computational cost even more critical. In order to reduce the computational burden related to the wave-induced fatigue analysis of Steel Catenary Risers (SCRs), this work presents the application of a recently developed hybrid methodology that combines dynamic Finite Element Analysis (FEA) and Artificial Neural Networks (ANN). The methodology is named hybrid once it requires short time series of structure responses (obtained by FEA) and imposed motions (evaluated analytically) to train an ANN. Subsequently, the ANN is employed to predict the remaining response time series using the prescribed motions imposed at the top of the structure by the floater unit. In this particular work, the methodology is applied aiming to predict the tension and bending moments’ time series at structural elements located at the top region and at the touchdown zone (TDZ) of a metallic riser. With the predicted responses (tensions and moments), the stress time series are determined for eight points along the pipe cross sections, and stress cycles are identified using a Rainflow algorithm. Fatigue damage is then evaluated using SN curves and the Miner-Palmgren damage accumulation rule. The methodology is applied to a SCR connected to a semisubmersible platform in a water depth of 910 m. The obtained results are compared to those from a full FEA in order to evaluate the accuracy and computer efficiency of the hybrid methodology.
40
UCHIYAMA, Hironobu, Yoshiharu KUSHIYA, and Masataka KUSUMI. "Tension Control of Cloth Spreading Mechine using Estimation Method of Curved Cloth Shape Based on Catenary Function. Accuracy of Estimated Shape and Controlled Performance on Steady Cloth Spreading Speed." Transactions of the Japan Society of Mechanical Engineers Series C 63, no. 612 (1997): 2731–38. http://dx.doi.org/10.1299/kikaic.63.2731.
Full text
41
Kovářík, Michal, Pavel Svoboda, and Henri Hubertus Achten. "Limits and Potential of 3D Printing Technologies for Construction of Concrete Shells." Solid State Phenomena 292 (June 2019): 249–56. http://dx.doi.org/10.4028/www.scientific.net/ssp.292.249.
Full textAbstract:
Concrete shells are a very effective type of building structures due to their ability to bridge large spans with minimal construction thickness. This type of building structures built on the medieval vaulting techniques and, regarding the use of reinforced concrete over the last 100 years, it has overcome the limitations of the masonry vaulting technologies and enabled to increase the span of structures to tens of meters. The construction technology to realize concrete shells using monolithic casting into formwork is besides abovementioned advantages characterized by high labour and thanks to the cost and manufacturing intensity of double curved formwork panels it allows economical realization of only selected structural geometries. Its considerable limitation is, besides the costly production of double curvature formwork, also the laborious installation of formwork and falsework structures. The solution seems to be in line with the upcoming transition to Construction 4.0 robotizing the construction technology of shells that could create a similar increase in productivity and design possibilities as was the technological transition between vaults and shells. One of the promising technologies of robotic production seems to be digital fabrication methods and, in particular, 3D printing or in other words additive manufacturing. This wasteless technology, which has been used to date for experimental projects mainly for the realization of vertical bearing structures, has, despite the first attempts at realizing vaults, a number of technological limitations. In this article, authors aim to summarize and indicate possible constraints of on site 3D printing of domes. They further indicate the possible ways to overcome these limitations and suggest two different means of on site 3D printing of hemispherical dome and the dome based on the catenary profile using extrusion nozzles with different profiles. Finally they discuss the Eurocode requirements for concrete shells and suggest technological solutions for on site 3D printed shells in terms of structural reinforcement.
42
Beividas, Waldir. "Um modelo catenário e tensivo para a estrutura do quadrado semiótico." Estudos Semióticos 15 (April 11, 2019): 39–53. http://dx.doi.org/10.11606/issn.1980-4016.esse.2019.156046.
Full textAbstract:
Este artigo visa explorar uma sugestão de Zilberberg, quando, numa reflexão en passant, propunha que “o categórico pressupõe o gradual que o funda” e que “o categórico é obtido pela suspensão dos termos catenários e conservação dos termos extremos” (1981, p. 10). Catenária – do latim catena [cadeia] – é definida em dicionário como uma curva na qual pende, sob a influência de seu próprio peso, um fio suspenso pelas extremidades. Essa figura geométrica permite “espelhar” o gradiente de tensividade – figura de um L, eixo intensivo na vertical e eixo extensivo na horizontal – acoplado a seu espelho (um L invertido), um segundo eixo intensivo e extensivo. O primeiro L responderia pela “tonicidade” (na verticalidade intensiva) e sua “degradação” (na horizontalidade extensiva) do termo primeiro (S1); o L invertido responderia pela tonicidade e degradação do termo segundo (S2). Em suma, duplica-se o gradiente tensivo para acolher os dois termos categoriais do quadrado semiótico que, assim, se “tensivisa”.
43
Fischer, T., M. Veste, O. Bens, and R. F. Hüttl. "Dew formation on the surface of biological soil crusts in central European sand ecosystems." Biogeosciences Discussions 9, no. 7 (2012): 8075–92. http://dx.doi.org/10.5194/bgd-9-8075-2012.
Full textAbstract:
Abstract. Dew formation was investigated in three developmental stages of biological soil crusts (BSC), which were collected along a catena of an inland dune and in the initial substrate. The Penman equation, which was developed for saturated surfaces, was modified for unsaturated surfaces and used for prediction of dewfall rates. The levels of surface saturation required for this approach were predicted using the water retention functions and the thicknesses of the BSCs. During a single event, dewfall increased with crust development from 0.08 kg m−2 for the initial substrate to 0.10, 0.20 and 0.25 kg m−2 for crusts stages 1 to 3, respectively, which was well reflected by the model response. The suggested mechanism of dew formation involves a delay in water saturation in near-surface soil pores and EPS where the crusts were thicker and where the water capacity was high, resulting in elevated vapor flux towards the surface. The results also indicate that the amount of dewfall was too low to observe water flow into deeper soil. Analysis of the soil water retention curves revealed that, despite the sandy mineral matrix, moist crusts with clogged by swollen EPS pores exhibited a clay-like behavior. It is hypothesized that BSCs gain double benefit from suppressing their competitors by runoff generation and from improving their water supply by dew collection. Despite higher amounts of dew, the water availability to the crust community decreases with crust development, which may be compensated by ecophysiological adaptation of crust organisms, and which may further suppress higher vegetation or mosses.
44
Palmero, D., M. De Cara, C. Iglesias, M. M. Moreno, N. González, and J. C. Tello. "First Report of Fusarium proliferatum Causing Rot of Garlic Bulbs in Spain." Plant Disease 94, no. 2 (2010): 277. http://dx.doi.org/10.1094/pdis-94-2-0277c.
Full textAbstract:
In October of 2008, decayed garlic bulbs (Allium sativum L. cv. Blancomor de Vallelado) were received from a producer in Segovia, Spain. In November of 2009, similar symptoms were observed on stored bulbs (cvs. Blancomor de Vallelado and Garcua) from each of 30 municipalities in northwest Segovia and Valladolid. A minimum of one sample was collected from 12 localities. Pieces of symptomatic bulbs were surface disinfested for 2 to 3 min in 0.5% NaOCl and transferred to potato dextrose agar (PDA) and Komada's media. Colonies had catenate microconidia and curved macroconidia that were usually three to five septate. Microconidia were club shaped with a flattened base, aseptate, and were produced on both mono- and polyphialides. On the basis of morphological features, the fungus was identified as Fusarium proliferatum (T. Matsushima) Nirenberg (2,3). Pathogenicity tests were conducted with 12 isolates of the fungi following the method of Dugan et al. (1). Each assay with an isolate consisted of six cloves (cv. Blancomor de Vallelado) disinfested in 0.5% NaOCl for 45 s, rinsed with sterile water, and injured to a depth of 4.5 mm with a probe 1 mm in diameter. The wound was filled with PDA colonized by the appropriate isolate. Six cloves for each tested isolate received sterile agar as a control. The cloves were incubated at 25°C for 5 weeks. The test was repeated once with cv. Garcua. All isolates produced water-soaked, tan lesions. An isolate of the fungus was deposited in the collection of the Plant Production Department of the University of Almeria. No fungi were recovered from the control cloves. F. proliferatum has been reported on garlic in the northwestern United States (1) and Serbia (4). To our knowledge, this is the first report of a Fusarium sp. in the section Liseola attacking garlic in Spain. The fungus seems to be well established on this host in Spain. References: (1) F. M. Dugan et al. Phytopathology 155:437, 2007. (2) P. E. Nelson et al. Fusarium Species: An Illustrated Manual for Identification. Pennsylvania State University Press, University Park, 1983. (3) H. Nirenberg et al. Mycologia 90:434, 1998. (4) S. Stankovic et al. Eur. J. Plant Pathol. 118:165, 2007.
45
Kwon, J. H., D. W. Kang, Y. S. Kwak, and J. Kim. "An Outbreak of Leaf Spot Caused by Corynespora cassiicola on Korean Raspberry in Korea." Plant Disease 96, no. 5 (2012): 762. http://dx.doi.org/10.1094/pdis-01-12-0020-pdn.
Full textAbstract:
In September and October 2010, leaf spots were observed on Korean raspberry (Rubus crataegifolius Bunge) plants in farmers' fields in Hapcheon, Gyeongnam Province, South Korea. Disease incidence ranged from 50 to 80% among fields. Circular- to irregular-shaped spots surrounded by yellow halos occurred frequently on the leaves of Korean raspberry plants. Brown spots became dark with wavy borders and ranged from 20 to 300 mm in diameter. Infected leaves became chlorotic, blighted, and eventually died. Fungal hyphae covered the lesions with abundant conidia and conidiophores. Fresh leaf specimens were collected from infected plants and the putative causal pathogen was isolated onto potato dextrose agar (PDA). A total of 30 isolates of the fungus were collected from diseased plants collected in the field. Fungal colonies were gray to brown on PDA. Colonies formed conidia, 38 to 210 × 8 to 20 μm, which were solitary or catenary, obclavate to cylindrical, smooth, straight or curved, and subhyaline to pale brown or brown. Conidiophores, 98 to 840 × 4 to 12 μm, were slightly or conspicuously swollen at apex, single, simple, straight or slightly flexuous, pale to midbrown, smooth, septate, thick, monotretic, and determinate or in tufts. Morphological characteristics of the fungal specimens were similar to descriptions of Corynespora cassiicola (1). A representative isolate of the pathogen was used to inoculate leaves of Korean raspberry plants for pathogenicity testing. Five leaves of a 3-month-old potted plant were sprayed with a suspension of conidia in water. Conidia were harvested from PDA cultures and adjusted to 2 × 104 conidia/ml with a hemocytometer. Five leaves sprayed with sterile distilled water served as controls. Inoculated plants were placed in a humid chamber with 100% relative humidity at 30°C for 24 h and then moved to a greenhouse. Symptoms similar to those observed in the farmers' fields developed on the inoculated leaves within 12 days, whereas the controls remained asymptomatic. The causal fungus was reisolated from the lesions of inoculated plants to satisfy Koch's postulates. To confirm the identity of the fungus, the complete internal transcribed spacer (ITS) rDNA region was amplified and sequenced (3). Amplification of the ITS region generated a 559-bp sequence (GenBank Accession No. JQ340026) with 100% similarity to sequences of C. cassiicola in GenBank (Accession No. GU138988) causing leaf spot on cassava (2). Based on the symptoms, morphological characteristics, pathogenicity, and molecular identification, this fungus was identified as C. cassiicola (1). To our knowledge, this is the first report of leaf spot caused by C. cassiicola on Korean raspberry. The recent occurrence of leaf spot on Korean raspberry suggests that C. cassiicola is spreading widely and posing a serious threat to these plants in Korea. References: (1) M. B. Ellis et al. No. 303 in: CMI Descriptions of Pathogenic Fungi and Bacteria. Surrey, Kew, UK, 1971. (2) X.-B. Liu et al. Plant Dis. 94:916, 2010. (3) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, Inc., New York, 1990.
46
Fischer, T., M. Veste, O. Bens, and R. F. Hüttl. "Dew formation on the surface of biological soil crusts in central European sand ecosystems." Biogeosciences 9, no. 11 (2012): 4621–28. http://dx.doi.org/10.5194/bg-9-4621-2012.
Full textAbstract:
Abstract. Dew formation was investigated in three developmental stages of biological soil crusts (BSC), which were collected along a catena of an inland dune and in the initial substrate. The Penman equation, which was developed for saturated surfaces, was modified for unsaturated surfaces and used for prediction of dewfall rates. The levels of surface saturation required for this approach were predicted using the water retention functions and the thicknesses of the BSCs. During a first field campaign (2–3 August 2011), dewfall increased from 0.042 kg m−2 for the initial sandy substrate to 0.058, 0.143 and 0.178 kg m−2 for crusts 1 to 3, respectively. During a second field campaign (17–18 August 2011), where dew formation was recorded in 1.5 to 2.75-h intervals after installation at 21:30 CEST, dewfall increased from 0.011 kg m−2 for the initial sandy substrate to 0.013, 0.028 and 0.055 kg m−2 for crusts 1 to 3, respectively. Dewfall rates remained on low levels for the substrate and for crust 1, and decreased overnight for crusts 2 and 3 (with crust 3 > crust 2 > crust 1 throughout the campaign). Dew formation was well reflected by the model response. The suggested mechanism of dew formation involves a delay in water saturation in near-surface soil pores and extracellular polymeric substances (EPS) where the crusts were thicker and where the water capacity was high, resulting in elevated vapor flux towards the surface. The results also indicate that the amount of dewfall was too low to saturate the BSCs and to observe water flow into deeper soil. Analysis of the soil water retention curves revealed that, despite the sandy mineral matrix, moist crusts clogged by swollen EPS pores exhibited a clay-like behavior. It is hypothesized that BSCs gain double benefit from suppressing their competitors by runoff generation and from improving their water supply by dew collection. Despite higher amounts of dew, the water availability to the crust community decreases with crust development, which may be compensated by ecophysiological adaptation of crust organisms, and which may further suppress higher vegetation or mosses.
47
Li, B. J., J. X. Chuan, M. Yang, and G. F. Du. "First Report of Corynespora Leaf Spot Caused by Corynespora cassiicola on Gynura in China." Plant Disease 98, no. 7 (2014): 1007. http://dx.doi.org/10.1094/pdis-12-13-1284-pdn.
Full textAbstract:
Gynura (Gynura bicolor DC.) is a perennial herbaceous plant in the family Compositae. It is an important Chinese vegetable, and is commonly used as a Chinese herbal medicine. In 2010, a severe leaf spot disease was observed on gynura grown in the main production areas in Tong Nan County, Chongqing City, China. Some farms experienced 60% disease incidence. Symptoms usually began on the lower leaves, as circular to elliptical or irregular spots with concentric rings. Individual spots were dark brown with grayish centers, sometimes coalescing and leading to extensive necrosis. The fungus associated with lesions was characterized as follows: Conidiophores were single or in clusters, straight or flexuous, unbranched, percurrent, cylindrical, pale to dark brown, 87.5 to 375.0 μm long and 5.0 to 10.5 μm wide. Conidia were solitary or catenate, straight to slightly curved, obclavate to cylindrical, 3 to 14 pseudoseptate, 82.8 to 237.5 μm long and 7.0 to 7.8 μm wide, and pale brown. The morphological characteristics of the conidia and conidiophores agreed with the descriptions for Corynespora cassiicola (1). To isolate the causal pathogen, surface-sterilized tissue at the margin of lesions was immersed in 75% ethanol for 30 s, rinsed in sterile water, dried in a laminar flow bench, transferred to PDA, and incubated at 28°C. Four single-spore cultures of the isolates were obtained and named from ZBTK10110637 to ZBTK10110640. All strains were identified as C. cassiicola. The isolate ZBTK10110637 was selected as representative for molecular identification. Genomic DNA was extracted by CTAB (2). The internal transcribed spacer (ITS) region of the rDNA was amplified using primers with ITS1 (5′-TCCGATGGTGAACCTGCGG-3′) and ITS4 (5′-TCCTCCGCTTATTGATATGC-3′). Amplicons were 433 bp (GenBank Accession No. JX867272) and shared 100% similarity with that of C. cassiicola (NRC2-1 No. AB539285.1). To confirm pathogenicity, four isolates were used to inoculate 12 gynura plants (6 weeks old) by mist spray-inoculation with 108 spores/ml suspension in sterile distilled water on the leaves. Control plants were misted with sterile distilled water. After inoculation, all plants were incubated in a greenhouse maintained at 20 to 28°C with relative humidity of 80 to 85%. Five days after inoculation, dark brown spots with a grayish center typical of field symptoms were observed on all inoculated plants. No symptoms were seen on water-treated control plants. The fungus was re-isolated from inoculated plants. The morphological characteristics of isolates were identical with the pathogen recovered originally. This is the first report of C. cassiicola on gynura. References: (1) M. B. Ellis. CMI Mycological Papers 65(9):1-15, 1957. (2) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990.
48
Fujiwara, Motohiro, Tatsuaki Goh, Satoru Tsugawa, Keiji Nakajima, Hidehiro Fukaki, and Koichi Fujimoto. "Tissue growth constrains root organ outlines into an isometrically scalable shape." Development 148, no. 4 (2021). http://dx.doi.org/10.1242/dev.196253.
Full textAbstract:
ABSTRACT Organ morphologies are diverse but also conserved under shared developmental constraints among species. Any geometrical similarities in the shape behind diversity and the underlying developmental constraints remain unclear. Plant root tip outlines commonly exhibit a dome shape, which likely performs physiological functions, despite the diversity in size and cellular organization among distinct root classes and/or species. We carried out morphometric analysis of the primary roots of ten angiosperm species and of the lateral roots (LRs) of Arabidopsis, and found that each root outline was isometrically scaled onto a parameter-free catenary curve, a stable structure adopted for arch bridges. Using the physical model for bridges, we analogized that localized and spatially uniform occurrence of oriented cell division and expansion force the LR primordia (LRP) tip to form a catenary curve. These growth rules for the catenary curve were verified by tissue growth simulation of developing LRP development based on time-lapse imaging. Consistently, LRP outlines of mutants compromised in these rules were found to deviate from catenary curves. Our analyses demonstrate that physics-inspired growth rules constrain plant root tips to form isometrically scalable catenary curves.
49
Martínez–Jiménez, Leonardo, Jorge Mario Cruz–Duarte, and J. Juan Rosales–García. "Fractional solution of the catenary curve." Mathematical Methods in the Applied Sciences, March 25, 2019. http://dx.doi.org/10.1002/mma.5608.
Full text
50
Hewitt, Paul. "Focus on Physics: The Delightful Catenary Curve." Science Teacher 084, no. 04 (2017). http://dx.doi.org/10.2505/4/tst17_084_04_14.
Full text