Stability Analysis of Line Patterns of an Anisotropic Interaction Model

We consider a class of interacting particle models with anisotropic, repulsive–attractive interaction forces whose orientations depend on an underlying tensor field. An example of this class of models is the so-called Kücken–Champod model describing the formation of fingerprint patterns. This class of models can be regarded as a generalization of a gradient flow of a nonlocal interaction potential which has a local repulsion and a long-range attraction structure. In contrast to isotropic interaction models the anisotropic forces in our class of models cannot be derived from a potential. The underlying tensor field introduces an anisotropy leading to complex patterns which do not occur in isotropic models. This anisotropy is characterized by one parameter in the model. We study the variation of this parameter, describing the transition between the isotropic and the anisotropic model, analytically and numerically. We analyze the equilibria of the corresponding mean-field partial differential equation and investigate pattern formation numerically in two dimensions by studying the dependence of the parameters in the model on the resulting patterns.

Radial and decentring distortion parameters have long been reported as fundamental elements in camera calibration, especially in digital close range photogrammetry. This paper reports on an investigation for the determination of both radial and decentring distortion parameters using analytical plumb‐line calibration. Straight line patterns, ranging from 1, 2, 4, 10 and up to 20 lines, not strictly plumb, are examined on a set of distorted imagery. Additionally, not only the number of straight lines but also the linear image distribution is analysed. For that purpose, linear features have been distributed in different positions and orientations over the whole of the imagery. Furthermore, the relationship between the parameters mentioned and the location of the principal point is also analysed, and shows how sensitive they are to deviations from the centre of the sensor. The motivation for this paper is the measurement of the minimum number of linear features for proper calibration of non‐metric digital cameras. Both radial and decentring distortion parameters are examined. Finally, some line patterns are recommended for making the plumb‐line calibration technique a reliable, easy and fast procedure. Photogrammetrists could use it as a first step in the procedure of camera calibration; users who are not experts in photogrammetry could employ it as a final step.

A new technique which permits the fabrication of submicrometer bubble propagation circuits has been described. Straight line patterns and contiguous zigzag patterns are combined with an appropriate registration to form bubble propagation patterns. The straight line pattern width corresponds to the gap width in the Permalloy bubble propagation circuits. By controlling the exposure time in fabricating straight line photoresist patterns, submicrometer pattern gaps are easily obtained using photomasks with 1 μm minimum features. The 4 μm period and 0.5 μm gap width permalloy circuits fabricated using this technique provide promising propagation characteristics for 1 μm bubbles: 60 Oe bias field margin at 60 Oe drive field and 25 Oe minimum propagation drive field.

Gravity is not the only ruler for falling events: Young children stop making the gravity error after receiving additional perceptual information about the tubes mechanism

A rule-based expert system is designed for steady-state stability analysis of a power system. In the proposed expert system approach, the key variables which affect steady-state stability most are first identified through discussions with operators and engineers. A number of offline studies (both eigenvalue analyses and time-domain simulations) are also conducted to help identify important system variables. A set of decision rules relating these key variables to system stability are then established and stored in the knowledge base. With these inference rules and system states at hand, the expert system performs steady-state stability analysis through deductive reasoning. Since the expert system approach does not require eigenvalue computation in making decisions, it is more efficient than the conventional method of steady-state stability analysis in real-time situations. The expert system was applied to steady-state stability analysis of the Taiwan power system. It was found that the expert system is useful to inexperienced operators, because of the knowledge of experienced operators and offline simulation studies stored in the expert system. >

Motivated by the simulation of fingerprints we consider a class of interaction models with anisotropic, repulsive‐attractive interaction forces whose orientations depend on an underlying tensor field. This class of models can be regarded as a generalization of a gradient flow of a nonlocal interaction potential which has a local repulsion and a long‐range attraction structure. These anisotropic forces in our class of models cannot be derived from a potential and the underlying tensor field introduces an anisotropy leading to complex patterns which do not occur in isotropic models. This anisotropy is characterized by one parameter in the model. We study the resulting stationary solutions both analytically and numerically by considering the particle model and its continuum counterpart.

Steady state and linear stability analysis of a supercritical water natural circulation loop

The stochastic nature of the wind causes various mechanical and electrical faults. It results the fluctuations in the output power. The high turbulence causes the dynamic loading of the drive train. To investigate the performance of the wind energy system its steady state and transient stability must be studied. This paper discuses the mathematical modeling of the wind energy system. With increase in size of wind turbines the shaft stiffness, viscous friction coefficient, drive train gear ratio and generator inertia constant have influence on the transient response of wind energy systems. The steady state and transient stability analysis with pole-zero study has been done by considering these four parameters. The severity of faults is studied in detail. This study intends the designing of fault tolerant control system in future.

Inkjet printing is an emerging technology with key advantages that make it suitable for the fabrication of stretchable circuits. Specifically, this process is cost-effective and less complex compared to conventional fabrication technologies. Inkjet printing has several process and geometry parameters that significantly affect the electromechanical properties of the printed circuits. This study aims to optimize the geometry parameters of inkjet-printed silver nanoparticle traces on plasma-treated polydimethylsiloxane (PDMS) substrates. The optimization process was conducted for two printed shapes, namely straight line and horseshoe patterns. The examined input factors for the straight line traces were: the number of inkjet-printed layers and line width. On the other hand, the number of cycles and amplitude were the examined input parameters for the horseshoe shape. First, the optimal number of layers and line width were found from the straight line analysis and subsequently were used in the optimization of the horseshoe pattern parameters. The optimization of the input parameters was carried out using the response surface methodology (RSM), where the objective of the optimization was to maximize the breakdown strain of the traces while maximizing the gauge factor and minimizing the ink cost. The results indicate that a 1.78 mm line width and one layer are the optimal geometry parameters for the straight line traces, while for the horseshoe pattern, the optimal parameters are one layer, a line width of 1.78 mm, amplitude of 4 mm and one cycle. The optimal straight line was designed to sustain up to 10% strain while the horseshoe pattern was designed to sustain up to 15% strain.

This article presented defected waveguide structure (DWS) designs and characteristics with microstrip‐fed circular monopole antenna for ultrawideband applications. Typically, waveguide is often designed and employed as antenna and filter application in its rigid dimension. The reconfigurable design toward the waveguide in terms of structural alteration with DWS was found less concerned among researchers although defected ground structure and defected microstrip structure have been applied widely. The motivation of this article was to propose the different DWS designs and characteristics in terms of the S‐parameters result. DWS in basic square geometry with different configurations of straight lines were introduced and compared with FR4 substrate waveguide. Simulated S‐parameters results were modeled in terms of equivalent circuit and measured for validation. For practical measurement, waveguide ports at both open‐ended surface of waveguide were replaced by the monopole antenna. For the modeled S‐parameters results, the square DWS design and square DWS with horizontal straight lines showed quite similar characteristics with higher S11 and lower S21 above frequency 9 GHz. Whereas square DWS with vertical straight lines and square DWS with both horizontal vertical straight lines showed higher S11 and lower S21 below frequency 3.5 GHz. Square DWS with vertical straight lines achieved the lowest S21 around −70 dB below 3.5 GHz and lower S21 around −50 dB at frequency 10.3 GHz. Thus, DWS is proposed for the future smart antenna technology as it can be further modified to meet the different requirements without changing the antenna configuration.

Control of the 1D self‐assembly pattern of colloidal quantum dots (QDs) on PbSO4 nanoribbon (NRb) templates is achieved. The internal structure of the NRbs is investigated by X‐ray diffraction, revealing the isotropic packing of the PbSO4 nanoclusters in the NRbs. Colloidal QDs in a chloroform/hexane mixture are adsorbed onto the region close to the edges of the NRbs and form a 1D assembly of straight single line or double lines by controlling the amount of OAm. This is the first demonstration of a densely packed 1D self‐assembly of colloidal QDs with a straight line pattern without the use of any molecular bridge or adhesive. Atomic force microscopy measurements of the NRbs show depressions in the phase profile along the width of the NRbs, corresponding to the position of the 1D QD chain. The amount of adsorbed QDs on the NRbs in solution decreases as the addition of OAm increases, suggesting that additional OAm prevents interaction between the QDs and NRbs but facilitates the uniform adsorption of the 1D assembly. The low‐dimensional self‐assembly of colloidal QDs in this study opens up the possibility for the creation of anisotropically assembled QD superstructures.

A diffractive optical element (DOE) aimed to reshape a Gaussian laser beam into a straight uniform light line is presented. Theory, the design procedure and technology are briefly described. Moreover a binary reflective DOE using a technology based on UV lithography and wet etching have been manufactured. Despite of a lot of fabrication errors, the DOE generates a bright and straight line pattern, which can be used in some technical areas.

Current underwater crawling vehicles could benefit by using rotating head sonar data to avoid collisions with obstacles. We have developed and optimized a fuzzy logic controller using software for simulation of an underwater environment. The optimization results show near an order of magnitude increase in performance over both straight line and lawnmower search patterns with relatively small changes in the system parameters. The fuzzy logic controller has the capability of navigating a crawler safely and quickly between mission specific points.

In a multi-robot system, following the leader is a challenge since the robot must detect the leader first and then responding accordingly. So, in this paper, the motion control of a group of robots is achieved based on the dynamic model of the collective motion behavior of the aggregation of Artemia, a creature that follows a spotlight. Modeling the collective behavior of Artemia that follows the spotlight will be inspiring for modeling a collective of robots that achieves the same tasks. The model is based on the newton equation and its parameters will be calculated directly from the features of the multi-robot system. Several experiments will be implemented to check the behavior of the proposed system, which is divided into four experiments according to four trajectories, the straight line, circle, zigzag and complex path pattern. The V-rep software is used to derive and simulate the proposed design, also test its performance.

Proprioceptive cues afforded by a head-coupled head-mounted display (HMD) may enable performance advantages over a manual joystick with stationary display for large-area search tasks. A study was conducted to determine the effects of various head-coupled and hand-controlled camera control/display configurations on a 360-degree search task within a teleoperated vehicle environment. Ten volunteers participated in a simulation, remotely controlling a camera's line-of-sight to acquire as many targets as possible within a two-minute period. Six camera control/display configurations were studied including various permutations of camera control (manual joystick or head-coupled; nominal or increased gain) and display (stationary CRT or HMD). Teleoperated vehicle path was also varied (straight line or figure-8 pattern). Performance data revealed that significantly more unique targets and significantly less duplicate targets were designated with the manual joystick/stationary CRT combination than with the head-coupled HMD configurations. Workload ratings, situation awareness ratings, and simulator sickness data generally favored the non-HMD configurations.