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Journal articles on the topic 'Cylindrical cams'
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1
Gao, Wei Qiang, Qiu Sheng Yan, J. Liang, and Z. Y. Liu. "Studies on NC Machining for Cylindrical Cams." Key Engineering Materials 291-292 (August 2005): 489–94. http://dx.doi.org/10.4028/www.scientific.net/kem.291-292.489.
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Cylindrical cam mechanisms have many merits, such as compact configuration, low cost, high reliability, better performance of kinematics and dynamics, and they have been widely used in fields of automatization and mechanization. Cylindrical cam mechanisms are the spatial mechanisms. Traditional methods of design and machining for cylindrical cam were complex, and it was difficult to ensure the precision of machining cylindrical cams, so it is impossible to meet the requirement of the development of high-speed automatic equipments. The better method of machining for cylindrical cams is to use the NC milling machine with 3 moving coordinates and 1 revolving coordinate. The key to realize the machining method is to resolve the problem of calculating tool’s paths for NC machining from the motion rule of followers of cam mechanisms. In this paper, the programming principle and technology of NC machining for cylindrical cams were analyzed, the compensation of cutting-tool radius for NC machining was discussed, the method of calculation for motion rule of cam followers and method of programming of NC machining with 4-coordinates were proposed, through which perfect effect have been gained in practice.
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LIU Bo, 刘波, 贾继强 JIA Ji-qiang, 丁亚林 DING Ya-lin, 苏东风 SU Dong-feng, and 张雷 ZHANG Lei. "Coaxial transmission mechanism based on cylindrical cams." Optics and Precision Engineering 20, no. 8 (2012): 1765–71. http://dx.doi.org/10.3788/ope.20122008.1765.
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Liu, Jen-Yu, and Hong-Sen Yan. "Surface Geometry of Variable Pitch Cylindrical Cams with Conical Meshing Elements." Journal of Mechanical Design 116, no. 3 (September 1, 1994): 862–66. http://dx.doi.org/10.1115/1.2919461.
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This paper presents mathematical expressions for the surface geometry of variable pitch cylindrical cams with four conical meshing elements based on the theory of conjugate surfaces. The unit normal of the element is derived, with given surface geometry of the meshing element, by differential geometry. The contact lines of the conjugate surface are defined according to the equation of meshing and the specified input-output relation. By the coordinate transformation of contact lines, we have the complete profile of the variable pitch cylindrical cam. The results of this work are instrumental in computer-aided manufacturing of variable pitch cylindrical cams for industrial applications.
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Yan, Hong-Sen, and Hsin-Hung Chen. "Geometry Design of Globoidal Cams With Generalized Meshing Turret-Rollers." Journal of Mechanical Design 118, no. 2 (June 1, 1996): 243–49. http://dx.doi.org/10.1115/1.2826876.
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This paper derives the generalized surface equation for cylindrical, conical, and hyperbolic meshing turret-rollers. Based on the generalized equation of meshing turret-rollers, generalized mathematical expressions of surface geometry for globoidal cams with cylindrical, conical, and hyperbolic meshing turret-rollers are derived using theory of conjugate surfaces, differential geometry, and coordinate transformation. A design example is presented for demonstrating procedures of surface generating of the globoidal cam. The result of this work is necessary for the computer-aided design and manufacturing of roller gear cams for industrial applications.
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Hwang, G. S., and D. M. Tsay. "Profile surfaces of cylindrical cams with arbitrarily-shaped followers." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 223, no. 8 (April 2, 2009): 1943–53. http://dx.doi.org/10.1243/09544062jmes1363.
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This study proposes an approach that is based on the theory of envelopes in a parametric form, to derive the analytical expressions of profile surfaces and pressure angles of the cylindrical cams with translating and oscillating arbitrary-shaped followers. The profile curvature is also analysed for the consideration of undercutting. The obtained results are feasible for various types of follower contours, which can be represented by parametric or explicit expressions, and then they can be thought of as the general forms of the cylindrical cam—follower mechanisms. The generalization and practicability in application of the results are also demonstrated in the design and numerical examples.
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Tsay, D. M., and B. J. Lin. "Profile Determination of Planar and Spatial Cams with Cylindrical Roller-Followers." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 210, no. 6 (November 1996): 565–74. http://dx.doi.org/10.1243/pime_proc_1996_210_231_02.
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A simple and useful procedure that can be used to determine profile surfaces of planar and spatial cams with cylindrical roller-followers is presented. Based on the rigid-body transformation between the cam and the roller-follower, the pitch (curve) surface which is the path of the point of the roller centre can be easily generated. Then the analytical profile surface of the cam can be represented by the offset surface of the pitch surface with a distance equal to the radius of the roller. To illustrate the ease and effectiveness of the approach, analytical expressions of profile surfaces of a disc cam, two cylindrical cams and two globoidal cams are typically given. Furthermore, in order to show the validity of this method, the results are then compared to those derived by an earlier procedure based on the screw theory.
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Hung, Jui Pin, Kuan Lin Chiu, and Yuan Lung Lai. "Tool-Path Generation for Conical Groove of Cylindrical Cams by Small-Sized Cutting Tools." Advanced Materials Research 189-193 (February 2011): 3046–49. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.3046.
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Instead of 2D expanding diagram method, this paper presents a new regenerating method for cutter location paths of using smaller tools to produce cylindrical cams. According to the expected motions, cams are put to use in various applications in mechanism. For a cylindrical cam, the roller follower operates in a groove cut on the periphery of an end mill with the diameter same as the roller. By using the conventional method, full-sized cutting tools, will restrict the flexibility of choosing cutting tools for wide roller guide. The manufacture of cylindrical cams is complicate and precise work that depends on the generating method and types of machine tools employed. Since the guiding curve cannot be offset exactly along the cylindrical surface, this leads to some approximating problems. Though the tool-paths generation by using the same size tools as rollers is applied in practice, the study of NC program by unequal tools is not available to meet high precision requirement. This proposed 3D offset-based generating method can regenerate tool-paths for standard cutting tools instead of larger ones and implemented on computerized CAM system. Examples with wider grooves are demonstrated to prove its effectiveness.
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Der Min Tsay and Hsien Min Wei. "Design and machining of cylindrical cams with translating conical followers." Computer-Aided Design 25, no. 10 (October 1993): 655–61. http://dx.doi.org/10.1016/0010-4485(93)90020-o.
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Yan, Hong-Sen, and Hsin-Hung Chen. "Geometry design and machining of roller gear cams with cylindrical rollers." Mechanism and Machine Theory 29, no. 6 (August 1994): 803–12. http://dx.doi.org/10.1016/0094-114x(94)90079-5.
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Mucino, V. H., J. E. Smith, and K. Sun. "Hydrodynamic mobility analysis of axial vane lift mechanisms in cylindrical cams." Industrial Lubrication and Tribology 52, no. 4 (August 2000): 178–85. http://dx.doi.org/10.1108/00368790010333629.
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Kang, Yaw-Hong, Jen-Yu Liu, and Hong-Sen Yan. "Curvature analysis of variable pitch cylindrical cams with conical meshing elements." Mathematical and Computer Modelling 19, no. 5 (March 1994): 51–64. http://dx.doi.org/10.1016/0895-7177(94)90090-6.
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Peng, Qing. "Discussion on the Accurate Modeling of Cylindrical Indexing Cam." Applied Mechanics and Materials 416-417 (September 2013): 1798–802. http://dx.doi.org/10.4028/www.scientific.net/amm.416-417.1798.
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Spatial indexing cam is widely used in some automation machineries, and usually can be classified into the following three types: (1) cylindrical indexing cam; (2) parallel indexing cam; (3) globular indexing cam. These cams have their own use range, and also are different in index number and application accuracy. In this paper, cylindrical indexing cam is mainly analyzed.
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Tsay, Der Min, and Bor Jeng Lin. "Improving the geometry design of cylindrical cams using nonparametric rational B-splines." Computer-Aided Design 28, no. 1 (January 1996): 5–15. http://dx.doi.org/10.1016/0010-4485(95)00020-8.
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Hung, Jui-Pin, and Yuan-Lung Lai. "Wide roller guide machining by four-axis machine tools for cylindrical cams." International Journal of Advanced Manufacturing Technology 62, no. 9-12 (January 25, 2012): 923–32. http://dx.doi.org/10.1007/s00170-011-3880-7.
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Zhang, Jie. "Research of the Virtual Prototype of the Balanced Elliptical Motion Shale Shaker." Applied Mechanics and Materials 397-400 (September 2013): 648–51. http://dx.doi.org/10.4028/www.scientific.net/amm.397-400.648.
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The working principle of the balanced elliptical motion shale shake are presented, Based on the way of parametric design with SolidWorks, The crucial technique for establishing the virtual model is discussed, uses the VBA development tools, realizes the cylindrical cams 3D parameterization design method and the step. The example was given to show the virtual design of the balanced elliptical motion shale shake is presented, the method can effectively improve design efficiency, Provide strong support for the launch of new products, which provides a feasible method for design of the balanced elliptical motion shale shake.
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Hsieh, J. "Design and machining of cylindrical cam with meshing indexing disc." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 221, no. 3 (March 1, 2007): 341–51. http://dx.doi.org/10.1243/0954406jmes188.
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Cams are fundamentally important machine elements, which provide a simple means of generating virtually any follower motion. This paper presents a simple yet comprehensive method for the design and machining of a cylindrical cam with a meshing indexing disc. In the proposed methodology, homogenous coordinate transformation and conjugate surface theory are employed to develop a kinematic model for the cam profile design. The pressure angle and the principal curvature of the designed cam are analysed using the analytical expression derived for the profile. The required NC data equations are obtained by solving the CNC link variables by equating the machine tool ability function with the tool location matrix. The proposed methodology is verified by machining the designed cylindrical cam using a 4-axis CNC machine. The inspection results obtained from a 4-axis CMM show that the profile measurements of the machining cam are in excellent agreement with those of the designed profile. The results confirm that the methodology presented in this study enables the cam design and manufacturing tasks to be successfully integrated. As a result, the production process is flexible, automatic, cost efficient, and controllable.
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Vekteris, Vladas. "The Use of Mechatronics for the Improvement of Grinding Accuracy." Solid State Phenomena 113 (June 2006): 137–42. http://dx.doi.org/10.4028/www.scientific.net/ssp.113.137.
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Various aspects of the improvement of the functioning of grinding accuracy are considered. Active methods of the control of grinding systems are proposed to ensure the quality required for finishing. It is pointed out that the quality of finishing is closely connected with the mutual position of the tool and the work piece in the grinding process. This position is appreciated by permissible state areas of the axis of the tool and the work piece. Analytical expression of this interaction is described by non-traditional mathematical model’s dependences. Mathematical models presented evaluate eccentricity between the tool and the work piece or between other elements of the system and enable one to better understand the appearance of the second and higher harmonics on the work piece processed or on the tool. They allow one to simulate the finishing not only of the cylindrical, but also of non-round profile work pieces, such as cams, eccentrics, etc. The mathematical dependences worked out allow one to build various modifications of the grinding systems and to evaluate the quality of their functioning. A circuit for the active control of the tool position is proposed, with the goal of quality improvement of finishing. For this purpose the usage of the adaptive spindle with tilting-pad journal bearings is suggested.
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Blinov, D. S., and I. S. Chunosov. "FEATURES OF MANUFACTURING TECHNOLOGY FOR THIN-WALLED PARTS." Spravochnik. Inzhenernyi zhurnal, no. 283 (October 2020): 15–26. http://dx.doi.org/10.14489/hb.2020.10.pp.015-026.
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In Russia, there is a tendency to revive the machine tool industry. From here, research in the field of mechanical engineering technology becomes relevant. The most popular research in the field of mechanical engineering technology is research on improving the manufacturing technology of thin-walled parts based on more reliable calculations. Axisymmetric thin-walled parts are very widely used in mechanical engineering, and they can be divided into rings and shells depending on the ratio of length to diameter. The objects of research in the article, which is staged in the cycle of works, are rings. The review and analysis of devices for installing thin-walled parts and methods for calculating errors from the action of fixing forces and cutting forces showed that standard cartridges are most often used for installing rings, and in the calculations of fixing forces are assumed to be concentrated (applied at a point). The work offers special devices–mandrels with wide cams, which are advisable to use when installing rings in mass production. The rings have a tolerance for the diameter of the base hole, which is intended to be used in the study. The purpose of the study is to develop an engineering method for calculating the shape error in the cross section of a thin-walled ring fixed by three wide mandrel сams, taking into account the width of the contact area and the initial radial gap between the diameter of the workpiece hole and the diameter of the working cylindrical surface of the cam. The tasks that will allow you to achieve the goal, the initial data, and a number of assumptions to simplify the study are identified.
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Blinov, D. S., and I. S. Chunosov. "FEATURES OF MANUFACTURING TECHNOLOGY FOR THIN-WALLED PARTS." Spravochnik. Inzhenernyi zhurnal, no. 283 (October 2020): 15–26. http://dx.doi.org/10.14489/hb.2020.10.pp.015-026.
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In Russia, there is a tendency to revive the machine tool industry. From here, research in the field of mechanical engineering technology becomes relevant. The most popular research in the field of mechanical engineering technology is research on improving the manufacturing technology of thin-walled parts based on more reliable calculations. Axisymmetric thin-walled parts are very widely used in mechanical engineering, and they can be divided into rings and shells depending on the ratio of length to diameter. The objects of research in the article, which is staged in the cycle of works, are rings. The review and analysis of devices for installing thin-walled parts and methods for calculating errors from the action of fixing forces and cutting forces showed that standard cartridges are most often used for installing rings, and in the calculations of fixing forces are assumed to be concentrated (applied at a point). The work offers special devices–mandrels with wide cams, which are advisable to use when installing rings in mass production. The rings have a tolerance for the diameter of the base hole, which is intended to be used in the study. The purpose of the study is to develop an engineering method for calculating the shape error in the cross section of a thin-walled ring fixed by three wide mandrel сams, taking into account the width of the contact area and the initial radial gap between the diameter of the workpiece hole and the diameter of the working cylindrical surface of the cam. The tasks that will allow you to achieve the goal, the initial data, and a number of assumptions to simplify the study are identified.
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WANG, ZONG-QING, HONG-YUN JIANG, and PING-ZHANG FENG. "Two new species of Anaplectoidea Shelford 1906 from China (Blattaria: Blattellidae)." Zootaxa 1160, no. 1 (March 27, 2006): 21. http://dx.doi.org/10.11646/zootaxa.1160.1.2.
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One known species, A. varia Bey-Bienko is illustrated for the first time, and two new species, A. cylindrica, sp. nov., A. spinea, sp. nov. are described and illustrated. A key to males from China is provided. The type specimens of new species are deposited in the Museum of Plant Protection, Institute of Plant Protection, Chinese Academy of Agricultural Sciences (IPP, CAAS).
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Andréka, H., and I. Németi. "On the number of generators of cylindric algebras." Journal of Symbolic Logic 50, no. 4 (December 1985): 865–73. http://dx.doi.org/10.2307/2273976.
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The theory of cylindric algebras (CA's) is the algebraic theory of first order logics. Several ideas about logic are easier to formulate in the frame of CA-theory. Such are e.g. some concepts of abstract model theory (cf. [1] and [10]–[12]) as well as ideas about relationships between several axiomatic theories of different similarity types (cf. [4] and [10]). In contrast with the relationship between Boolean algebras and classical propositional logic, CA's correspond not only to classical first order logic but also to several other ones. Hence CA-theoretic results contain more information than their counterparts in first order logic. For more about this see [1], [3], [5], [9], [10] and [12].Here we shall use the notation and concepts of the monographs Henkin-Monk-Tarski [7] and [8]. ω denotes the set of natural numbers. CAα denotes the class of all cylindric algebras of dimension α; by “a CAα” we shall understand an element of the class CAα. The class Dcα ⊆ CAα was defined in [7]. Note that Dcα = 0 for α ∈ ω. The classes Wsα, and Csα were defined in 1.1.1 of [8], p. 4. They are called the classes of all weak cylindric set algebras, regular cylindric set algebras and cylindric set algebras respectively. It is proved in [8] (I.7.13, I.1.9) that ⊆ CAα. (These inclusions are proper by 7.3.7, 1.4.3 and 1.5.3 of [8].)It was proved in 2.3.22 and 2.3.23 of [7] that every simple, finitely generated Dcα is generated by a single element. This is the algebraic counterpart of a property of first order logics (cf. 2.3.23 of [7]). The question arose: for which simple CAα's does “finitely generated” imply “generated by a single element” (see p. 291 and Problem 2.3 in [7]). In terms of abstract model theory this amounts to asking the question: For which logics does the property described in 2.3.23 of [7] hold? This property is roughly the following. In any maximal theory any finite set of concepts is definable in terms of a single concept. The connection with CA-theory is that maximal theories correspond to simple CA's (the elements of which are the concepts of the original logic) and definability corresponds to generation.
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Díaz de la Torre, Sebastián, Ladislav Čelko, Mariano Casas Luna, and Edgar Benjamin Montúfar Jimenéz. "On the Preparation of Advanced Materials via Pulsed Electric Current Sintering Procedures." Solid State Phenomena 258 (December 2016): 436–39. http://dx.doi.org/10.4028/www.scientific.net/ssp.258.436.
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A general overview on the processing of a series of advanced engineering materials, synthesized via pulsed-electric-current-sintering related techniques, and the similarities in between those techniques are introduced in this work. This paper is focused on two major techniques; namely, the Spark Plasma Extrusion (SPE) and Current Assisted Infiltration Sintering (CAIS), which in turn are derived from the Spark Plasma Sintering (SPS) technique, all widely used by this research group. Not only the geometry but also the microstructure of thus prepared specimens might vary depending on the selected technique. The resulting specimens can be under the forms of discs (flat or thick coin-like), rivets (enlarged cylindrical bars)-like and/or disclosing interpenetrated periodic networks with regular or irregular (either coin or rivet/screw)-like specimens, respectively. As for the CAIS technique, either 3D printed ceramic frameworks or naturally synthesized porous substrates (such as bone-like structures), can be infiltrated with virtually any metal or alloy. Among the series of produced materials we can include, for example: biomaterials such as: Ti-and Mg-hydroxyapatite, pure hydroxyapatite HA, composites, e.g., Al5083-CNT ́s, just to name a few. The expanding possibilities of SPS, SPE and CAIS techniques are briefly indicated here.
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Skláršová, B., P. Šimko, P. Šimon, and E. Belajová. "Characterisation of physicochemical interactions between benzo(a)pyrene contained in vegetable oil and polyethylene terephtalate." Czech Journal of Food Sciences 22, SI - Chem. Reactions in Foods V (January 1, 2004): S276—S279. http://dx.doi.org/10.17221/10680-cjfs.
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Rapeseed oil was spiked with benzo(a)pyrene [BaP] solution at the level of 29.4 μg/kg, filled into polyethylene terephtalate [PET] cylindrical shape receptacles and the BaP concentrations were followed for during 97 h by HPLC. During this time, the BaP concentrations decreased to 22.9 μg/kg due to an interaction of BaP with PET. Using a modified kinetic equation, the diffusion coefficient for BaP in the oil was determined. Calculation of the area occupied by a BaP molecule on PET surface suggests that either the multilayer adsorption or the diffusion of BaP into PET bulk came into account as the decisive factors bringing about the decrease of BaP concentrations in the oil.
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Volkova, S. N., A. V. Shleenko, V. V. Morozova, and E. E. Sivak. "Analysis of Linear Surfaces of Building Structures." Proceedings of the Southwest State University 24, no. 3 (December 6, 2020): 111–20. http://dx.doi.org/10.21869/2223-1560-2020-24-3-111-120.
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Purpose of reseach is to analyze the practice in the application of surfaces formed by the movement of a straight line. It is known that among the second-order surfaces cones, cylinders, hyperboloids of one sheet and hyperbolic paraboloids, as well as lines represented in the polar coordinate system in the form of intricate shapes that can be represented in space by the above-mentioned surfaces, adding a third dimension, have rectilinear generators. The strength resulting from covering each point of the listed surfaces with straight lines from different families does not make the structure heavier but strengthens it and makes it light compared to monoliths without reinforcements made of other materials, in which stability is not based on Shukhov calculation formulas. Methods Finding families of rectilinear generators for second-order surfaces calculation of which is based on the separation of equations that represent a second-order surface as a difference of squares in one part of the equation and as a product with an arbitrary parameter in the other part. Results. Analyzing second-order surfaces, we came to the conclusion that cones, cylinders are prone to this method of Shukhov calculations; equation of the form F (x,y)=0 in space defines a cylindrical surface whose generators are parallel to axis oz. Similarly, F (x, z)=0 defines a cylindrical surface with generators parallel to axis oy and F (y;z)=0 is a cylindrical surface with generators parallel to axis ox. A hyperboloid of one sheet, hyperbolic paraboloid, i.e. 10 surfaces out of 14, make up more than 70%. Conclusion. As a result of applying these formulas for calculating reinforced building structures, city buildings will acquire a new appearance, which will create a comfortable environment for residents, as well as lead to saving construction material resources.
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Vieira, Carlos Maurício Fontes, and Sérgio Neves Monteiro. "Incorporation of Granite Waste into Vitrified Ceramic Tiles." Materials Science Forum 530-531 (November 2006): 467–72. http://dx.doi.org/10.4028/www.scientific.net/msf.530-531.467.
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The incorporation of a granite waste into a vitrified ceramic tile body was investigated. The granite waste came from an industry of stone sawing operations located in the municipal area of Santo Antônio de Pádua, State of Rio de Janeiro, Brazil. The investigated compositions were elaborated substituting partially and totally the feldspar by the granite waste. Cylindrical specimen were prepared by uniaxial pressure at 30 MPa and then fired at temperatures varying from 1050 to 1200oC. Fired properties such as bulk density, linear shrinkage, water absorption and diametrical compression were determined. The microstructure of fired samples was evaluated by scanning electron microscopy. The results showed that the replacement of feldspar by granite waste promoted a better vitrification, decreasing the open porosity and increasing the mechanical strength.
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Σκόρδου, Μαρία. "Γυάλινο ανάγλυφο κύπελλο από την Κίσαμο, ΒΔ Κρήτη." Fortunatae. Revista Canaria de Filología, Cultura y Humanidades Clásicas, no. 32 (2020): 741–56. http://dx.doi.org/10.25145/j.fortunat.2020.32.47.
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Our knowledge of the Roman city and necropolis of Kissamos was enriched, on occasion of a project carried out under the supervision of the Ephorate of Antiquities of Chania, in 2015.In the west cemetery of ancient Kissamos, a new family rock-cut chamber tomb came to light. The rectangular subterranean chamber of a trapezoidal vertical section with a roof opening, received multiple burials. The offerings, included several mainly glass unguentaria, clay vessels, bone objects, beads and gold sheets, demonstrate the long use of this family grave, from the 1st c.A.D. to the 3rd c. A.D. Of particular interest is an imported mold-blown glass drinking vessel of luxury ware. It is an inscribed cylindrical beaker of the 1st c. AD, bearing the Greek inscription “ΛΑΒΕ ΤΗΝ ΝΕΙΚΗΝ(incorrect orthography for “CATCH THE VICTORY”).
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Lomtadze, Maka. "USING A FUNCTION DERIVATIVE IN ECONOMIC TASKS." Economic Profile 16, no. 1(21) (July 16, 2021): 93–99. http://dx.doi.org/10.52244/ep.2021.21.09.
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The article focuses on the application of mathematical methods in economics, in particular discussing economic problems that are easily solved using derivatives. The purpose of the article is to show students the way and opportunity to use mathematical methods to solve economic problems. To this end, the article discusses and analyzes several economic tasks in detail, which will be interesting and easy for students to master. I considered the derivative of a function as the rate of change and introduced the definition: The instantaneous rate of change of the function f with respect to x at a point is called the derivative if it exists. With the help of this definition I have discussed and explained Task 1: Suppose that the increase in production of a certain product over a period of time is described by a function And population growth is described by the following function: Where is the number of years from the initial period, then the production of these products per capita is given by the function: Find the growth rate of product production. By solving this task I came to the conclusion that after a year the production of products per capita increases. In the following tasks I used the method of finding the extremum values of a function using a derivative, namely I equated the first-order derivative to 0, found the critical points, and with the help of the second-order derivative I determined the extremes of the function. I discussed task 2: For the production of X volume of products, the firm plans a cost that is calculated by the formulan . For what volume of production will the average cost be the smallest? Find the numerical value of this small expense. Solving this problem, I came to the conclusion that the given function of the average cost takes on the least value when the output volume is a unit , and this value is equal to: which is the marginal cost when producing the volume output. I discussed Task 3: How many products should be sold in order for a firm to profit maximally if the derivative cost function is known: And return function: Here I came to the conclusion: if 600 units of the product are sold, then the firm's profit will be maximum and it will be numerically equal At the end of the article I discussed such a task 4 of applied optimization. What is the minimum amount of material needed to make a 2 liter cylindrical jar? Where I came to the conclusion: the smallest amount of material will be spent to get a cylindrical vessel if we take the height 2 times the radius of the base.
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Gomes, Daniel, and Antonio C. de O. Ferraz. "Mechanical behavior of 'Niagara Rosada' grape berry detachment." Engenharia Agrícola 31, no. 6 (December 2011): 1115–22. http://dx.doi.org/10.1590/s0100-69162011000600009.
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The 'Niagara Rosada' grape is the main Brazilian table grape belonging to the Labrusca family. It develops medium, cylindrical and compact bunches with berries presenting a pinkish skin and a foxy flavor that is valued in the Brazilian market. These berries are tender and have a pedicel-berry connection provided by the vascular bundles and surrounding skin. This cultivar is very susceptible to berry drop mainly caused by vibration and senescence. The objective of this study was to evaluate the temporal mechanical behavior of the pedicel-berry detachment, using resistance indexes extracted from traction force-deformation curves. Test results showed two different detachment types. In the first one, which exhibited higher average resistance, a considerable portion of the vascular bundle came out attached to the pedicel and in the second type; the vascular bundle was retained inside the berry. The proposed indexes based on maximum detachment force, force at 0.2; 0.5; 1.0 and 1.2 mm, and maximum force to corresponding deformation ratio did not discriminate the senescence of the berry.
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Horsley, G. H. R. "Two New Milestones from Pisidia." Anatolian Studies 39 (December 1989): 79–84. http://dx.doi.org/10.2307/3642814.
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By the end of 1987 three successive seasons had been spent by a team co-directed by Dr. S. Mitchell and Professor M. Waelkens at the Augustan colony of Cremna, and two (plus a brief initial season in 1985) at Pisidia's chief city in Roman Imperial times, Sagalassos. The permit for a surface survey has provided the opportunity to locate and check a considerable percentage of the texts previously known. It has also made possible the discovery of several new inscriptions from these sites and their territory. Two new milestones are presented here, one pertaining to each city.In early August 1987, on the last evening of my stay with the team working at Sagalassos, I was taken by two men from Aǧlasun 4 km. along the Aǧlasun–Isparta road. Turning right into a lane, after some 300 m. we came to a small bridge over a stream. Nearby was a large cylindrical stone (Pl. XVII(a)) which had recently been recovered from the stream during excavations for another bridge.
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Tulum, Isil, Yuhei O. Tahara, and Makoto Miyata. "Peptidoglycan layer and disruption processes in Bacillus subtilis cells visualized using quick-freeze, deep-etch electron microscopy." Microscopy 68, no. 6 (November 5, 2019): 441–49. http://dx.doi.org/10.1093/jmicro/dfz033.
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Abstract Peptidoglycan, which is the main component of the bacterial cell wall, is a heterogeneous polymer of glycan strands cross-linked with short peptides and is synthesized in cooperation with the cell division cycle. Although it plays a critical role in bacterial survival, its architecture is not well understood. Herein, we visualized the architecture of the peptidoglycan surface in Bacillus subtilis at the nanometer resolution, using quick-freeze, deep-etch electron microscopy (EM). Filamentous structures were observed on the entire surface of the cell, where filaments about 11 nm wide formed concentric circles on cell poles, filaments about 13 nm wide formed a circumferential mesh-like structure on the cylindrical part and a ‘piecrust’ structure was observed at the boundary. When growing cells were treated with lysozyme, the entire cell mass migrated to one side and came out from the cell envelope. Fluorescence labeling showed that lysozyme preferentially bound to a cell pole and cell division site, where the peptidoglycan synthesis was not complete. Ruffling of surface structures was observed during EM. When cells were treated with penicillin, the cell mass came out from a cleft around the cell division site. Outward curvature of the protoplast at the cleft seen using EM suggested that turgor pressure was applied as the peptidoglycan was not damaged at other positions. When muropeptides were depleted, surface filaments were lost while the rod shape of the cell was maintained. These changes can be explained on the basis of the working points of the chemical structure of peptidoglycan.
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Zhang, Fang, Jiao Jiao Li, Rui Jiang, Shan Shan Zhang, Tian Zhu, and Shen Zhou Lu. "Excellent Cell Compatibility in Time Controlled Silk Fibroin Hydrogels." Materials Science Forum 815 (March 2015): 407–11. http://dx.doi.org/10.4028/www.scientific.net/msf.815.407.
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Various methods were developed to prepare hydrogels including photo-cross-linking, chemical cross-linking, enzymatic cross-linking, pH or temperature-induced gelation, ionic interaction, and hydrophobic interactions. Whereas silk fibroin gelation time was difficult to control by physical methods, the cross-linkers used in chemical technique were likely to reduce the cell biocompatibility. Sodium N-Lauroyl Sarcosinate (SNS), an amino acid-based surfactant, came into accelerate silk fibroin to form silk hydrogel. To monitor the gelation process and determine the gelation time, turbidity changes during gelation were measured by Synergy HT. Cylindrical gels have been measured with universal material experiment machine and KES for mechanical properties. Fibroblast (L929) cells were seeded on the surface of hydrogels to investigate the cell compatibility. The results show that the SNS/SF gelation time ranges from 20 min to 120 min, which is affected by environment temperature, the final concentrations of SF and SNS. Compared with pure silk fibroin hydrogels, the compression strength of SNS/SF gel is much stronger. SNS/SF gel has excellent compression-recovery performance in KES test as well. A logarithmic stable cell growth appears on the surface of SNS/SF hydrogels, which indicates that SNS/SF hydrogels have excellent cell compatibility. Therefore, the SNS/SF hydrogels have great potential in tissue repair for surgery.
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BECKETT, F. M., H. M. MADER, J. C. PHILLIPS, A. C. RUST, and F. WITHAM. "An experimental study of low-Reynolds-number exchange flow of two Newtonian fluids in a vertical pipe." Journal of Fluid Mechanics 682 (July 28, 2011): 652–70. http://dx.doi.org/10.1017/jfm.2011.264.
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We present an experimental study of a buoyancy-driven, low-Reynolds-number (Re < 1) exchange flow of two Newtonian fluids in a vertical cylindrical pipe (length 1 m and diameter 38.4 mm) connecting two fluid reservoirs. The denser, more viscous fluid was golden syrup and the less dense, less viscous fluid was a golden syrup–water solution; the ratio of the viscosities of the two fluids (β) ranged from 2 to 1180. Flows were initiated by removing a bung in the base of the upper reservoir or sliding out a gate positioned at the top, middle or bottom of the pipe. We observe the flows over long time durations (up to 356 h), and define the development of the flow with reference to a non-dimensional time (τ). The initial transient development of the flow was dependent on which of the two fluids initially filled the pipe, but this did not systematically affect the flow regime observed at τ ≫ 1. Two distinct flow regimes were observed: axisymmetric core-annular flow (CAF), in which the less viscous fluid occupies a cylindrical core and the denser fluid flows downwards in an annulus, and side-by-side (SBS) flow where both fluids are in contact with the pipe and there is a single interface between them. CAF formed at β ≥ 75 and SBS flow at β ≤ 117. In several experiments, for 5 ≤ β ≤ 59, a slowly developing transitional SBS (TSBS) flow was observed where SBS flow and CAF occurred simultaneously with SBS in the lower portion of the pipe; SBS existed throughout most of the pipe and in one case grew with time to entirely fill the pipe. Velocity profiles determined by tracking tracer particles show that the observed CAFs are adequately described by the formulation of Huppert & Hallworth (J. Fluid Mech., vol. 578, 2007, pp. 95–112). Experimental SBS velocity profiles are not well produced by the formulation of Kerswell (J. Fluid Mech., 10.1017/jfm.2011.190), possibly because the latter is restricted to flows whose cross-section has an interface of constant curvature. Despite the variations in flow regime, volume fluxes can be described by a power-law function of β, Q1 = 0.059 β−0.74. A comparison of experimental data with the theoretical approaches of Huppert Hallworth (2007) and Kerswell (2011) indicates that fluids are not arranged in the regime that maximises volume flux (e.g. SBS or CAF), nor do they adopt the geometry that maximises volume flux within that particular regime.
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Zhang, Kaiting, Yong Guo, Fangcheng Yuan, Tingting Zhang, Zhenzhen Zhu, Beibei Weng, ShanShan Wu, Tong Chen, and Yuxia Chen. "Effect of Chemical Treatments on the Properties of High-Density Luffa Mattress Filling Materials." Materials 12, no. 11 (June 3, 2019): 1796. http://dx.doi.org/10.3390/ma12111796.
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Luffa is a lightweight porous material with excellent biocompatibility and abundant resources. In this paper, three kinds of softening treatment methods, alkali-hydrogen peroxide (Method 1), alkali-acetic acid (Method 2), and alkali-urea (Method 3), were used to soften high-density (HD) cylindrical luffa (CL) mattress-filling materials (MFM). Microscopic observation, mechanical performance testing and other analyses were performed to evaluate the effects of the three kinds of softening methods on the wettability, compression resilience and support performance of CL MFM. The results showed that: (1) After the treatment by Method 1, Method 2 and Method 3, the peak stress of CL decreased by 73%, 10% and 27%, respectively. In addition, after three kinds of softening treatments, the uniformity of CL increased. (2) When the CL MFM of high density rank treated by Method 1 was compressed by 40%, the firmness values of the surface, core and bottom reduced by 53.49% 40.72%, and 46.17%, respectively, compared to that of untreated CL. In addition, for the CL MFM of high density rank treated by Method 3 and then compressed to 60%, the firmness of the surface layer, core layer and bottom layer reduced by 41.2%, 33.7%, and 36.9%, respectively. (3) The contact angle of luffa treated by Method 3 was the smallest, next came Method 1 and Method 2, and untreated was the largest. (4) After the treatment by Method 3, the fiber bundle of luffa was intact, and the compression resilience of the CL was obviously increased. Therefore, this method can effectively reduce the firmness of MFM and also improve the uniformity and wettability of CL.
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Smith, Richard S. "Using combinations of spatial gradients to improve the detectability of buried conductors below or within conductive material." GEOPHYSICS 78, no. 1 (January 1, 2013): E19—E31. http://dx.doi.org/10.1190/geo2012-0210.1.
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The detection of conductive bodies is an important capability when exploring for massive sulfide deposits or looking for unexploded ordnance. When these bodies are buried below conductive overburden or embedded in conductive material, the use of an electromagnetic system to identify the bodies becomes problematic because the response of the overlying conductive material can be much greater that the response of the buried conductor. I calculated the response of five models representing different conductivity distributions (a buried conductor, a uniform overburden with changes in the system altitude, a paleochannel, a thicker overburden, and a thinner overburden). The subtle response of the buried conductor was difficult to identify because it looked very similar to the responses of other structures that are not necessarily of interest. The spatial gradients for the same five models showed that the greatest improvement in the relative size of the anomalous gradient response compared with the background gradient came for the cases in which the material closest to the surface changes, in particular the paleochannel and thickening overburden models. However, identification of the deeper buried conductor was still problematic because of the large background gradients. In theory, the cylindrical symmetry of a dipole transmitter over a layered earth ensured that there were exact relations between the spatial derivatives. Hence it was possible to define two specific combinations that should be zero over a layered earth. Calculating these combinations for the five models showed that the anomalous zones stood out with significantly greater anomaly-to-background ratios. The measurement of the gradients and the calculation of these combinations therefore provided a means of identifying anomalous zones in and below a conductive earth. Different relative sizes and shapes of the two combinations for different models provided a way of discriminating between the vertical conductor model and the four other models.
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Ammari, A., K. Bouassria, N. Zakham, M. Cherraj, H. Bouabid, and S. Charif D’ouazzane. "Durability of the earth mortar: Physico-chemical and mineralogical characterization for the reduction of the capillary rise." MATEC Web of Conferences 149 (2018): 01024. http://dx.doi.org/10.1051/matecconf/201814901024.
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The stabilization of the earth material in the fields related to the earthen construction, in compliance with the standards in force, allows strong results of strength and durability. The chemical and mineralogical elements play an important role, in the presence of an 'optimum' cement dosage, to strengthen the ties between the clays and the grains of the earth.. This approach targets the search for better performances in the use of natural materials resource in an eco-responsible habitat. This study presents the experimental results of the four techniques of mineralogical and chemical analysis on mortar specimens obtained from earth of the city of Fez. The results of the uni-axial compressive tests of the cylindrical specimens for this earth, associated by various percentages 0%, 4%, 7% and 10% by weight of cement, make it possible to analyze the effect of the mineralogical and chemical elements on the mechanical properties, namely Young's modulus, compressive strength and limiting deformation. However, we determine the water absorption coefficient of the mortar for different cement dosages in order to optimize the durability of the mortar against bad weather, rain and / or very wet climates. In the earth mortar of Fez, the strong presence of calcite (CaCO3), quartz SiO2 and dolomite CaMg (CO3)2 amplifies the improvement of the behavior of the material by the addition of cement. In fact, this strong presence of calcite stabilized the clay by cementing quartz and the cement matrix to strengthen the ties between the grains of the earth. In addition, with respect to the capillary rise, the water absorption decreases with the addition of cement. We also note that the evolution of the mechanical properties is of no importance except in the interval [4 to 7%] which represents the zone of effect for cement stabilization and which houses the optimum technicoeconomic cement dosing.
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Werle, Sebastian, and Mariusz Dudziak. "Influence of Wastewater Treatment and The Method of Sludge Disposal on the Gasification Process." Ecological Chemistry and Engineering S 21, no. 2 (July 8, 2014): 255–68. http://dx.doi.org/10.2478/eces-2014-0020.
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Abstract Municipal wastewater treatment results in the production of large quantities of sewage sludge, which requires proper environmentally accepted management before final disposal. Sewage sludge is a by-product of current wastewater treatment technologies. Sewage sludge disposal depends on the sludge treatment methods used in the wastewater treatment plant (anaerobic or aerobic digestion, drying, etc.). Taking into consideration presented given this information, a study concerning the effects of wastewater treatment processes and sewage sludge drying method on the sewage sludge gasification gas parameters was performed. Gasification is a prospective alternative method of sludge thermal treatment. For the purpose of experimental investigations, a laboratory fixed bed gasifier installation was designed and built. Two types of sewage sludge feedstock, SS1 and SS2, were analyzed. Sewage sludge SS1 came from a wastewater treatment plant operating in the mechanical and biological system while sewage sludge SS2 was collected in a mechanical, biological and chemical wastewater treatment plant with simultaneous phosphorus precipitation. The sludge produced at the plants was subject to fermentation and then, after being dehydrated, dried in a cylindrical drier on shelves heated up to 260ºC (sewage sludge SS1) and using hot air at a temperature of 150ºC in a belt drier (sewage SS2). The analysis shows that the sewage sludge properties strongly depend on the wastewater sources and the wastewater treatment processes. The gasification results, presented as a function of the amount of gasification agent, show that the greater oxygen content of SS1 caused a reduction in the reaction temperature. Paradoxically, this effect caused an increase in the quantity of combustible components in the gas. As expected, increasing the air flow rate caused a decrease in the heating value of the gas produced. A higher amount of oxidizer increases the amounts of noncombustible species and the volumetric fraction of nitrogen, thus reducing the heating value of the obtained gas. The higher hydrogen content in SS1 affects the gasification gas composition. As a result, combustible components are the majority of the syngas.
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Pedro Saad, Davi, Gabriel Cabral Serra, Isa Lorena Silva Barbosa, and Ana Lúcia Carrijo Adorno. "UTILIZAÇÃO DE FIBRA DE BORRACHA DE PNEU COMO AGREGADO NA COMPOSIÇÃO DE CONCRETO." Revista Gestão, Inovação e Negócios 3, no. 1 (June 21, 2017): 107. http://dx.doi.org/10.29246/2358-9868.2017v3i1.p107-129.
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Resumo A indústria do processo de recauchutagem de pneus gera resíduos que em sua maioria têm sido descartados sem nenhum controle. Este fato contribui para aumentar a poluição ambiental e favorecer a proliferação de vetores nocivos à saúde. Visando encontrar uma aplicação para esse tipo de resíduo, neste trabalho são apresentados resultados experimentais de amostras que tiveram o intuito de avaliar o comportamento e a viabilidade do uso de fibra de borracha proveniente de pneu, adicionada em forma de agregado no concreto, com o objetivo de obter um possível material alternativo para a indústria da construção civil, contribuindo para a proteção ambiental. Prepararam-se uma dosagem de concreto sem resíduos de borracha, para servir de referência, e três diferentes dosagens contendo resíduos de borracha, com substituição do volume do agregado em 5%, 10% e 15%. Aos sete e vinte e oito dias as amostras produzidas, no total de 80 corpos de prova cilíndricos de 15 x 30 cm2, foram submetidas ao ensaio de resistência mecânica à compressão simples. Conclui-se que com a utilização das fibras de pneu, o concreto sofre uma perca de resistência em todos os casos, contudo, os traços com as porcentagens de 5% e 10%, além de um custo menor, atingiram resistência para serem utilizados em elementos não estruturais, como calçadas. Palavras-chave: Pneus inservíveis. Fibra de borracha. Agregado. Concreto. Reciclagem. Abstract The tire retreading industry generates waste residues that has mostly been disposed of without any control. This contributes to increasing environmental pollution and promoting the proliferation of vectors that are harmful to people’s health. With the aim to find an application for this type of residue, experimental results of samples with the intention of evaluating the behavior and the feasibility of the use of rubber fiber from tires were presented throughout this article. Such samples were added as an aggregate in the concrete, with the objective of obtaining a possible alternative material for the construction industry that would contribute to environmental protection. A dosage of rubber-free concrete to serve as reference was prepared, and three different dosages containing rubber residues were prepared with 5%, 10% and 15% volume substitution of the aggregate. After the seventh and the twenty-eighth day, the samples produced, in the total of 80 cylindrical specimens of 15x30 cm², were submitted to the mechanical test of simple compression. We came to conclusion that, with the use of the tire fibers, the concrete undergoes a loss of resistance in all cases. However, the traces with the percentages of 5% and 10%, in addition to a lower cost, reached resistance that allowed it to be used in non-structural elements such as sidewalks. Keywords: Wasted tires. Rubber fiber. Aggregate. Concrete. Recycling.
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del Río, L. E., C. A. Bradley, and B. L. Johnson. "First Report of White Mold Caused by Sclerotinia sclerotiorum on Echium (Echium vulgare)." Plant Disease 89, no. 6 (June 2005): 684. http://dx.doi.org/10.1094/pd-89-0684c.
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Echium, also known as common viper's bugloss, is a member of the botanical family Boraginaceae. Echium is being evaluated for its potential use as an oilseed crop in North Dakota. In 2003, 40% of echium plants in a field in Cass County were observed showing classical symptoms of infection by Sclerotinia sclerotiorum. Plants in advanced stages of infection were dead. Stems of dead plants peeled off easily when touched and numerous cylindrical, black sclerotia that were 2 to 3 mm in diameter and 4 to 7 mm long were found in the pith. Younger stem lesions were watery soft, many of them with a white cottony growth on them. Sclerotia and infected stem tissues collected from the field were surface disinfested in a 0.5% NaOCl solution for 30 s, rinsed with sterile distilled water, and air dried before plating on potato dextrose agar (PDA). Samples were incubated at room temperature for 1 week. White mycelium and black sclerotia, characteristic of S. sclerotiorum (Lib.) de Bary, were produced in all dishes. Koch's postulates were fulfilled using the petiole inoculation technique (2). Briefly, 4-mm agar plugs containing hyphal tips of a 2-day-old S. sclerotiorum colony growing on PDA were excised and loaded in the wide opening of 100-μl pipette tips. The second true leaf of 15 3-week-old echium seedlings, growing in plastic pots containing Ready-Mix soil, was cut off with a razor blade leaving an approximately 25-mm long petiole attached to the stem. The leafless petioles of 10 seedlings were capped with a loaded pipette, agar plug first, until the petiole tip broke the inner surface of the plug and the petiole came in contact with the mycelium. The other five seedlings were inoculated with agar plugs without mycelium and used as control plants. Three days after inoculation, all seedlings inoculated with S. sclerotiorum wilted and expressed symptoms similar to those observed in the field. None of the control plants showed symptoms of infection. Black sclerotia were retrieved from infected stems 2 weeks after inoculation, and the pathogen was successfully reisolated onto PDA. Several important North Dakota crops are susceptible to S. sclerotiorum. The identification of echium as a new host for S. sclerotiorum should be considered in the event that this crop is promoted as an alternative for North Dakota agriculture. To our knowledge, this is the first report on the susceptibility of echium to S. sclerotiorum. Other members of the Boraginaceae have been identified as hosts for this pathogen (1). References: (1) G. J. Boland and R. Hall. Can. J. Plant Pathol. 16:93, 1994. (2) L. E. del Río et al. (Abstr.) Phytopathology 91 (suppl.):S176, 2001.
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Palmateer, A. J., R. C. Ploetz, E. van Santen, and J. C. Correll. "First Occurrence of Anthracnose Caused by Colletotrichum gloeosporioides on Pitahaya." Plant Disease 91, no. 5 (May 2007): 631. http://dx.doi.org/10.1094/pdis-91-5-0631a.
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Pitahaya, Hylocereus undatus Britt. & Rose, is a columnar, climbing cactus that produces a commercially important fruit. In December 2004, a new disease was found on the crop in Miami-Dade County, FL. Reddish brown lesions with conspicuous chlorotic haloes developed concentrically on the edges of vine ribs. Lesion centers became white and coalesced to rot much of the vine column, and in severe cases, only the vascular column in the vine center was not diseased. Salmon-colored spores and waxy, subepidermal acervuli, typically with setae and simple, short, erect conidiophores, were observed in lesion centers. Tissue from lesion margins was surface disinfested and plated on potato dextrose agar (PDA; Difco Laboratories, Detroit, MI). Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. was isolated from all samples. Colonies produced abundant conidia that were hyaline, one celled, straight, cylindrical, and averaged 14.7 × 5.0 μm with ranges of 12.5 to 17.5 × 3.8 to 7.5 μm (1). Cultural and morphological characteristics of isolates matched those for C. gloeosporioides except for appressoria and hyphopodia (1,2); pitahaya isolates had a spherical rather than lobed hyphopodia reported for C. gloeosporioides and averaged 10.9 (8.5 to 12.7) × 9.1 (7.1 to 10.3) μm. Internal transcribed spacer sequences for the pitahaya isolates were nearly identical (98% homology) to those for C. gloeosporioides isolates occurring on Euphatorium thymifolia in Thailand (GenBank Accession No. AY266393). Koch's postulates were examined in greenhouse trials at the Tropical Research and Education Center, Homestead, FL. Treatments consisted of a noninoculated control, four C. gloeosporioides isolates, and an Alternaria sp. All isolates came from symptomatic pitahaya tissue collected in Miami-Dade County. Fungi were grown on PDA for 7 days at 27°C. A sterile dissecting needle was used to gently pinprick the epidermis of the stem and 2-mm-diameter plugs of C. gloeosporioides, an Alternaria sp., or clean PDA were placed over wounds. Plants were placed in a plastic tent in a greenhouse where the temperature was held at 25°C, and free moisture was maintained on plant surfaces with a household humidifier for 48 h following inoculation. Two isolates of C. gloeosporioides were shown, in repeated greenhouse experiments, to cause reddish brown lesions with conspicuous chlorotic haloes that coalesced to rot much of the vine column, and Koch's postulates were completed with the reisolation of isolates that were used to inoculate plants. The age of vine segments had no significant effect on lesion development. To our knowledge, this is the first report of C. gloeosporioides as a pathogen of pitahaya. References: (1) J. A. Bailey and M. J. Jeger. Colletotrichum: Biology, Pathology and Control. CAB International, Wallingford, UK, 1992. (2) M. Du et al. Mycologia 97:641, 2005.
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He, Y., C. Shu, J. Chen, and E. Zhou. "First Report of Anthracnose of Alocasia macrorrhiza Caused by Colletotrichum karstii in Guangdong, China." Plant Disease 98, no. 5 (May 2014): 696. http://dx.doi.org/10.1094/pdis-10-13-1046-pdn.
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Alocasia macrorrhiza (L.) Schott. (Araceae), native to South America, is a common, herbaceous perennial ornamental plant in tropical and subtropical areas (1). A severe leaf spot disease was observed on this plant in several places on the campus of authors' university in Guangzhou, Guangdong Province, China, in April 2013. Initial symptoms were water-soaked, dark green leaf spots. These small spots gradually expanded to 6- to 11-mm circular lesions. They were grayish-white in color with a yellow halo and many small, black, concentric dots were observed on them. Microscopic examination revealed that these small dots were acervuli, which were 100 to 300 μm in diameter, developing beneath the epidermis and becoming erumpent with age. By using routine tissue-isolation method and single-spore purification technique, four single-conidial isolates were obtained from each of four diseased leaves. These isolates formed a grayish-white colony with numerous pink spore masses on PDA at 28°C. Their mycelial radial growth rate was about 4.5 mm per day. Conidia were single-celled, hyaline, and cylindrical with an obtuse apex and protruding base; they were 12.7 to 14.2 × 4.8 to 5.9 μm in size. Conidial appressoria were irregular in shape, sepia to dark brown, solitary, and 6.9 to 8.5 × 4.6 to 5.9 μm. These morphological characteristics were consistent with the description of Colletotrichum karstii (2). The sequences of beta-tubulin gene (TUB2) and partial actin gene (ACT) of a representative isolate CAM1 were obtained by PCR amplification with primers BT2a/BT2b and ACT512F/ACT783R, respectively. These sequences were deposited in GenBank under the accession numbers of KF444947 and KF460435. BLAST searches showed a 99% homology with the TUB2 and ACT sequences of C. karstii (JX625209, KC843559). Therefore, the fungus isolated from A. macrorrhiza was identified as C. karstii by morphological and molecular characteristics. Pathogenicity tests were performed on 30-day-old plants of A. macrorrhiza grown in plastic pots (0.8 L) by spraying 15 ml conidial suspension (1 × 106 conidia ml–1) of this fungus onto each plant. The control plants were sprayed only with sterile distilled water. These plants then were placed in an intelligent artificial climate incubator with 12-h photoperiod and 100% relative humidity at 24 ± 1°C. Three replicates, each with five plants, were included in a test, and the test was repeated twice. Seven days after inoculation, the inoculated plants showed necrotic lesions on leaves similar to those observed on the campus, but no symptoms were observed on any non-inoculated controls. The same fungus C. karstii was re-isolated from the infected leaves. Although C. karstii is a well-known anthracnose pathogen on some plants belonging to family Orchidaceae (2), this is the first report of the same pathogen causing anthracnose on A. macrorrhiza in Guangdong, China. References: (1) S. Li et al. PLoS ONE 8(6):e66016, 2013. (2) Y. Yang et al. Cryptogr. Mycol. 32:229, 2011.
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Ozgoren, M. Kemal. "Kinematic Analysis of Spatial Mechanical Systems Using a New Systematic Formulation Method for Lower and Higher Kinematic Pairs." Journal of Mechanisms and Robotics 6, no. 4 (June 5, 2014). http://dx.doi.org/10.1115/1.4027233.
Full textAbstract:
This paper presents a new systematic formulation method to describe all kinds of lower and higher kinematic pairs and to express the pertaining kinematic relationships. The method can be applied to any mechanical system, which may be a mechanism or a manipulator, but it may especially be convenient for a system with multijoint links and multiaxis joints, such as a parallel manipulator. The method is based on the kinematic elements of the joints. In the first stage of the method, a joint frame is attached to every kinematic element hosted by the links of the system. It is attached in such a way that its relative position with respect to the link frame of the hosting link is described by a minimal number of essential parameters that are necessary and sufficient to represent all the characteristic features of the kinematic element. To systematize the attachment of the joint frames, the kinematic elements are classified into six types according to their geometric complexity. The link frames may also be attached judiciously to further minimize the total number of parameters required by the whole system. In the second stage of the method, the necessary equations are written to express the relative position between the mating kinematic elements of each joint. In the paper, such equations are written for a set of typical lower and higher kinematic pairs including samples ranging from a revolute joint up to a spatial cam joint. The application of the method is demonstrated on two mechanisms. One of them is a two-loop spatial mechanism with five different joints and the other one is a single-loop spatial cam mechanism with ellipsoidal and cylindrical cams. For each mechanism, the loop closure equations are first written and then simplified to prepare for solution to determine the unspecified joint variables. Afterward, the semi-analytical solutions of the loop closure equations are described and discussed.
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Sharma, Ravinder, Rupinder Singh, Ajay Batish, and Nishant Ranjan. "On synergistic effect of BaTiO3 and graphene reinforcement in polyvinyl diene fluoride matrix for four dimensional applications." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, September 27, 2021, 095440622110157. http://dx.doi.org/10.1177/09544062211015763.
Full textAbstract:
This work presents the synergistic effect of BaTiO3 and graphene (Gr) reinforcement in polyvinyl diene fluoride (PVDF) matrix by chemical-assisted mechanical blending (CAMB) for possible 4D applications. The PVDF matrix was prepared (in form of filament) by solvent casting followed by twin-screw extrusion (TSE) as CAMB process. The filament was used on fused deposition modelling (FDM) setup for preparing standard flexural and pull-out specimens. The mechanical testing revealed that the parts printed with 100% in-fill density (ID), 70 mm/s infill speed (IS), and 45° in-fill angle (IA) has shown better flexural strength (FS). For pull-out properties, part printed at IS 90 mm/s, 0° IA, and 100% ID have shown better results. Further optimized settings of FS were used to 3D print thin cylindrical discs followed by electric poling (for possible piezoelectric properties). The results of X-ray diffraction (XRD) and Fourier transmission infrared spectroscopy (FTIR) analysis show more β-phase formation in the electrically poled sample as compared to non-poled specimen. Moreover, XRD spectra show the homogenous dispersion of doped material in the PVDF matrix. The piezoelectric coefficient (d33) 30.2pC/N was observed on 3D printed specimen (prepared from filament processed with CAMB), suitable for 4D applications.
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Bazhin, V. Yu, G. V. Konovalov, T. R. Kosovtseva, and J. Schenk. "From Henry Bessemer’s invention to comprehensive converter process optimization." Tsvetnye Metally, October 30, 2020, 88–95. http://dx.doi.org/10.17580/tsm.2020.10.11.
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The Bessemer process enabling to produce high-quality steels was implemented at steel mills of the Urals region more than 200 years ago. At the beginning of the 20th century, the process was modified by scientists from the Mining Institute and was then adopted by copper and nickel alloy producers. The converter process became one of the key processing stages with Russian copper and nickel smelters. This paper examines certain ways to improve the tuyere air flow in a horizontal converter. The authors came up with a generic equation for calculating specific blast air pressure and discuss the use of hydrothermal and aerodynamic techniques for tuyere purging. The blast air limit was determined for a horizontal converter that is characterized with massive melt ejections. The authors demonstrate that, in spite of all the process and design improvements, the modern converter process still has three major drawbacks. They include process cycling, the gas ductwork not being completely tight, unbalanced thermal and chemical status of the vessel leading to excessive thermal and chemical loads on the tuyere zone and incomplete slag formation in zones that are farther from the tuyeres. Research work is ongoing on a novel continuous converter design which involves the use of special-design unsubmerged tuyeres. Such tuyeres produce spatially oriented high-pressure blasts which enable consistent rotation of the molten matte in a tight cylindrical vessel.