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51.
Hybrid Petri net (HPN) is an extension of the Petri net formalism, which enables us to handle continuous information in addition
to discrete information. Firstly, this paper demonstrates how biological pathways can be modeled by the integration of discrete
and continuous elements, with an example of the λ phage genetic switch system including induction and retroregulation mechanisms.
Although HPN allows intuitive modeling of biological pathways, some fundamental biological processes such as complex formation
cannot be represented with HPN. Thus, this paper next provides the formal definition of hybrid functional Petri net with extension
(HFPNe), which has high potential for modeling various kinds of biological processes. Cell Illustrator is a software tool
developed on the basis of the definition of HFPNe. Hypothesis creation by Cell Illustrator is demonstrated with the example
of the cyanobacterial circadian gene clock system. Finally, our ongoing tasks, which include the development of a computational
platform for systems biology, are presented. 相似文献
52.
We study a crossing minimization problem of drawing a bipartite graph with a radial drawing of two orbits. Radial drawings are one of well-known drawing conventions in social network analysis and visualization, in
particular, displaying centrality indices of actors (Wasserman and Faust, Social Network Analysis: Methods and Applications. Cambridge University Press, Cambridge,
1994). The main problem in this paper is called the one-sided radial crossing minimization, if the positions of vertices in the outer orbit are fixed. The problem is known to be NP-hard (Bachmaier, IEEE Trans. Vis.
Comput. Graph. 13, 583–594, 2007), and a number of heuristics are available (Bachmaier, IEEE Trans. Vis. Comput. Graph. 13, 583–594, 2007). However, there is no approximation algorithm for the crossing minimization problem in radial drawings. We present the first polynomial time constant-factor approximation algorithm for the one-sided radial crossing minimization problem. 相似文献
53.
54.
This study addresses the optimal changes in geometry of a two-dimensional variable geometry truss (VGT) to identify the stiffness matrix of the truss using the concept of self-identification. The optimization of the geometry changing of the VGT is a problem of selecting the optimal combination of multiple design variables from a large number of candidate sets. This study proposes a simple optimization method for determining a set of optimal geometric parameters; in this method, the approximated mode shape matrix obtained using spline interpolation techniques is used to calculate the objective function for self-identification. The objective function used in this paper is a function of the condition number of the coefficient matrix of a linear matrix equation and a criterion for self-identification. The proposed algorithm can be used to reduce the number of actual vibration tests required for measuring the mode shapes and modal frequency while it maximizes the objective function. Numerical experiments are conducted to investigate the relationship between the convergence characteristics of the optimization and the target vibration modes. The effectiveness of the optimized geometry changing is verified by comparing the identification error for the uniform geometry changing, the optimized one for the three lower modes of the VGT, and the one found by a classical QR decomposition. Furthermore, the numerical results show that the identification sensitivity with respect to noisy data is reduced by the optimization. 相似文献
55.
Recently, various techniques of shape reconstruction using cast shadows have been proposed. These techniques have the advantage
that they can be applied to various scenes, including outdoor scenes, without using special devices. Previously proposed techniques
usually require calibration of camera parameters and light source positions, and such calibration processes limit the range
of application of these techniques. In this paper, we propose a method to reconstruct 3D scenes even when the camera parameters
or light source positions are unknown. The technique first recovers the shape with 4-DOF indeterminacy using coplanarities
obtained by cast shadows of straight edges or visible planes in a scene, and then upgrades the shape using metric constraints
obtained from the geometrical constraints in the scene. In order to circumvent the need for calibrations and special devices,
we propose both linear and nonlinear methods in this paper. Experiments using simulated and real images verified the effectiveness
of this technique. 相似文献
56.
The purpose of this study was to design an endoscopic dissector handle and objectively assess its usability. The handles were designed with increased contact area between the fingers and thumb and the eye rings, and the eye rings were modified to have a more perpendicular insertion angle to the finger midline. Four different handle models were compared, including a conventional product. Subjects performed dissection, exclusion, grasping, precision manipulation and precision handling tasks. Electromyography and subjective evaluations were measured. Compared to conventional handles, the designated handle reduced the muscle load in the extensor and flexor muscles of the forearm and increased subjective stability. The activity of the first dorsal interosseous muscle was sometimes influenced by the shape of the other parts. The ergonomically designed endoscopic dissector handle used in this study achieved high usability. Medical instrument designs based on ergonomic concepts should be assessed with objective indices.
Practitioner Summary: The endoscopic dissector handles were designed with increased contact area and more suitable insertion angle between the fingers and thumb and the eye rings. Compared to conventional handles, the designated handle reduced the muscle load in the extensor and flexor muscles of the forearm and increased subjective stability. 相似文献
57.
58.
The conjugate gradient method is an effective method for large-scale unconstrained optimization problems. Recent research has proposed conjugate gradient methods based on secant conditions to establish fast convergence of the methods. However, these methods do not always generate a descent search direction. In contrast, Y. Narushima, H. Yabe, and J.A. Ford [A three-term conjugate gradient method with sufficient descent property for unconstrained optimization, SIAM J. Optim. 21 (2011), pp. 212–230] proposed a three-term conjugate gradient method which always satisfies the sufficient descent condition. This paper makes use of both ideas to propose descent three-term conjugate gradient methods based on particular secant conditions, and then shows their global convergence properties. Finally, numerical results are given. 相似文献
59.
To examine gender differences in hand stability, finger position and force holding tasks at low force levels were conducted with 30 male and 30 female young adults. Total fluctuation was defined as the standard deviation of measured data and fluctuation and the 10-Hz component of the physiological tremor were compared between maleand female subjects. In all tasks, the total fluctuation and the 10-Hz tremor were significantly larger in male subjects than females. On average, the fluctuation was 1.3 times larger and the 10-Hz tremor was 1.6 times larger. The results of this study suggest that women have superior hand stability compared with men at low force levels. Finger length, maximal voluntary contraction and surface electromyography were also measured and factors related to gender differences in hand stability are discussed. STATEMENT OF RELEVANCE: Hand stability is crucial for precise manual operations. This study demonstrated gender differences in hand steadiness at low force levels. Though hand dexterity cannot be explained only by hand stability, the results of this study are useful not only for occupational aptitude tests but also for neuropsychological tests. 相似文献
60.
Vibration control of load for rotary crane system using neural network with GA-based training 总被引:4,自引:0,他引:4
Kunihiko Nakazono Kouhei Ohnishi Hiroshi Kinjo Tetsuhiko Yamamoto 《Artificial Life and Robotics》2008,13(1):98-101
A neuro-controller for vibration control of load in a rotary crane system is proposed involving the rotation about the vertical
axis only. As in a nonholonomic system, the vibration control method using a static continuous state feedback cannot stabilize
the load swing. It is necessary to design a time-varying feedback controller or a discontinuous feedback controller. We propose
a simple three-layered neural network as a controller (NC) with genetic algorithm-based (GA-based) training in order to control
load swing suppression for the rotary crane system. The NC is trained by a real-coded GA, which substantially simplifies the
design of the controller. It appeared that a control scheme with performance comparable to conventional methods can be obtained
by a relatively simple approach.
This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January
31–February 2, 2008 相似文献