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مرکز اطلاعات علمی SID1
اسکوپوس
دانشگاه غیر انتفاعی مهر اروند
ریسرچگیت
strs
Journal: 

AMIRKABIR

Issue Info: 
  • Year: 

    2006
  • Volume: 

    16
  • Issue: 

    63-E
  • Pages: 

    35-41
Measures: 
  • Citations: 

    0
  • Views: 

    78514
  • Downloads: 

    32895
Abstract: 

The SYMMETRIC curvature and associated curvatures of a vector bundle E with connection Ñ on a manifold M with connection Ñ were introduced. It is well-known that a total space of semi-Riemannian vector bundle over a semi-Riemannian manifold can be made into a semi-Riemannian manifold. In this case, the relation between curvatures of the Levi-Civita connections of E and M was studied. Here, the relation between SYMMETRIC curvatures of the Levi-Civita connections and their associated curvatures of E and M is studied.

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Issue Info: 
  • Year: 

    2011
  • Volume: 

    37
  • Issue: 

    3
  • Pages: 

    249-267
Measures: 
  • Citations: 

    0
  • Views: 

    84731
  • Downloads: 

    34776
Abstract: 

Recently, we have used the SYMMETRIC BRACKET of vector fields, and developed the notion of the SYMMETRIC derivation. Using this machinery, we have defined the concept of SYMMETRIC curvature. This concept is natural and is related to the notions divergence and Laplacian of vector fields. This concept is also related to the derivations on the algebra of SYMMETRIC forms which has been discussed by the authors. We introduce a new class of geometric vector fields and prove some basic facts about them. We call these vector fields affinewise. By contraction of the SYMMETRIC curvature, we define two new curvatures which have direct relations to the notions of divergence, Laplacian, and the Ricci tensor.

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Issue Info: 
  • Year: 

    2011
  • Volume: 

    5
  • Issue: 

    4
  • Pages: 

    111-118
Measures: 
  • Citations: 

    0
  • Views: 

    129183
  • Downloads: 

    86489
Abstract: 

Background and aims: Diverse gauges have been used to measure and determine BRACKET height for correct BRACKET positioning. The aim of the present study was to determine and compare BRACKET positioning accuracy by using height BRACKET positioning gauge (HBPG) and Boone gauge (BG).Materials and methods: Nineteen sets of stone models were prepared from one patient. One set was employed to determine the ideal position of BRACKETs, and the remaining nine pairs of sets for BRACKET placement by nine clinicians using HBPG and BG. Teeth were then sectioned from the stone models and placed inside acrylic molds, photographs were taken and imported to a computer. In two groups, the position of each bonded BRACKET was compared in three aspects of vertical, mesiodistal and angular with the ideal position of every BRACKET. Finally, BRACKET positioning errors were measured.Results: Mann-Whitney U test demonstrated significant differences in the means of vertical error between the HBPG group and BG groups (P<0.001), while there were no significant differences between mesiodistal and angular errors. Factorial ANOVA revealed that gauge and tooth type, and the position of tooth on the right and left side of the mouth play a ma-jor role in the rate of vertical error.Conclusion: Vertical accuracy of BRACKET positioning by the use of HBPG is more than that by BG. However, there is no difference between two gauges in relation to the mesiodistal and angular errors.

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گارگاه ها آموزشی
Author(s): 

Issue Info: 
  • Year: 

    2018
  • Volume: 

    8
  • Issue: 

    4
  • Pages: 

    296-303
Measures: 
  • Citations: 

    415
  • Views: 

    2313
  • Downloads: 

    20659
Keywords: 
Abstract: 

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Author(s): 

UR REHMAN F.

Issue Info: 
  • Year: 

    2004
  • Volume: 

    3
  • Issue: 

    1
  • Pages: 

    72-78
Measures: 
  • Citations: 

    0
  • Views: 

    50581
  • Downloads: 

    28134
Abstract: 

This paper presents two different kinds of regulating control strategies for the angular velocity of a rigid body model with two torque actuators. The first strategy presents piece-wise constant, states dependent feedback control laws. The method is based on the construction of a cost function V (not a Lyapunov function), which is sum of two semi-positive definite functions 1 V and 2 V. The semipositive definite function 1 V is dependent on the first m state variables which can be steered along the given vector fields and 2 V is dependent on the remaining m n - state variables which can be steered along the missing LIE BRACKETs. The values of the functions 1 V and 2 V allow in determining a desired direction of system motion and permit to construct a sequence of controls such that the sum of these functions decreases in an average sense. The second strategy presents a time-varying feedback law based on the model reference approach, where the trajectory of the extended system is chosen as the model reference trajectory. The controllers are designed in such a way that after each time period T, the trajectory of the rigid body model intersects the trajectory of the model reference which can be made asymptotically stable. The proposed feedback law is as a composition of a standard stabilizing feedback control for a LIE BRACKET extension of the original system and a periodic continuation of a specific solution to an open loop control problem stated for an abstract equation on a LIE group.

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Author(s): 

ABD EL SALAM F.A.

Issue Info: 
  • Year: 

    2013
  • Volume: 

    37
  • Issue: 

    A3
  • Pages: 

    199-210
Measures: 
  • Citations: 

    0
  • Views: 

    101029
  • Downloads: 

    66583
Abstract: 

Using the Riemann-Liouville fractional differintegral operator, the LIE theory is reformulated. The fractional Poisson BRACKET over the fractional phase space as 3N state vector is defined to be the fractional LIE derivative. Its properties are outlined and proved. A theorem for the canonicity of the transformation using the exponential operator is proved. The conservation of its generator is proved in a corollary. A Theorem for the inverse fractional canonical mapping is proved. The composite mappings of two successive transformations is defined. The fractional LIE operator and its properties are introduced. Some useful lemmas on this operator are proved. LIE transform depending on a parameter over the fractional phase space is presented and its relations are proved. Two theorems that proved the transformation F= EW Z is completely canonical and is a solution of the Hamiltonian system (30) are given. Recurrence relations are obtained.

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strs
Issue Info: 
  • Year: 

    2008
  • Volume: 

    19
  • Issue: 

    2
  • Pages: 

    153-157
Measures: 
  • Citations: 

    0
  • Views: 

    94595
  • Downloads: 

    35946
Abstract: 

We define a new function-valued inner product on L2(G), called j-BRACKET product, where G is a locally compact abelian group and j is a topological isomorphism on G. We investigate the notion of j -orthogonality, Bessel's Inequality and j -orthonormal bases with respect to this inner product on L2(G).

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Issue Info: 
  • Year: 

    2011
  • Volume: 

    5
  • Issue: 

    1
  • Pages: 

    38-50
Measures: 
  • Citations: 

    0
  • Views: 

    118090
  • Downloads: 

    51361
Abstract: 

The purpose of this paper is to introduce the concept of a cone SYMMETRIC space and to investigate relationship between (cone) metric spaces and (cone) SYMMETRIC spaces. Among other things, we shall also extend some fixed point results from metric spaces to cone metric spaces (Theorem 3.3), and to SYMMETRIC spaces (Theorems 3.2 and 3.5) under some new contraction conditions.

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Author(s): 

PARK C.

Journal: 

JOURNAL OF LIE THEORY

Issue Info: 
  • Year: 

    2005
  • Volume: 

    15
  • Issue: 

    -
  • Pages: 

    393-414
Measures: 
  • Citations: 

    458
  • Views: 

    16725
  • Downloads: 

    28684
Keywords: 
Abstract: 

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Author(s): 

NEMATI H. | GHOBADI M.S.

Journal: 

STRUCTURE AND STEEL

Issue Info: 
  • Year: 

    2017
  • Volume: 

    13
  • Issue: 

    20
  • Pages: 

    5-21
Measures: 
  • Citations: 

    0
  • Views: 

    53317
  • Downloads: 

    30405
Abstract: 

Construction of welded moment resisting connection is common. These connections have high potential for brittle failure of welds if quality of welding is not controlled. In this research new bolted BRACKET connection similar to Kaiser bolted BRACKET connection is introduced. Kaiser connection has invention patent so construction society can’t utilize them without authority. Proposed connection of this paper can be manufactured by both casting and welding methods and can eliminate patent problems. In this evaluation connection performance, pretention force of bolts, height of BRACKET, number of bolts and length of BRACKET have been evaluated. In modeling of connection in order to accuracy of results between different connected area and bolts faces contact elements were created. The standard cyclic history was selected for loading of specimens. The results shows that proposed connection can be accepted by connection code for using in special moment resisting frames from both ductility and strength aspects. Findings are extended as hysteresis curves, released energy of connection, rupture index indicators and slip of bolts.

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