Sampled-data fuzzy controller for continuous nonlinear systems

The sampled-data fuzzy control of nonlinear systems is presented. The consequents of the fuzzy controller rules are linear sampled-data sub-controllers. As a result, the fuzzy controller is a weighted sum of some linear sampled-data sub-controllers that can be implemented by a microcontroller or a digital computer to lower the implementation cost. Consequently, a hybrid fuzzy controller consisting of continuous-time grades of memberships and discrete-time sub-controller is obtained. The system stability of the fuzzy control system is investigated on the basis of Lyapunov-based approach. The sampling activity introduces discontinuity to complicate the system dynamics and make the stability analysis difficult. The proposed fuzzy controller exhibits a favourable property to alleviate the conservativeness of the stability analysis. Furthermore, linear matrix inequality-based performance conditions are derived to guarantee the system performance of the fuzzy control system. An application example is given to illustrate the merits of the proposed approac

The Entanglement in Anisotropic Heisenberg XYZ Chain with inhomogeneous magnetic field

The thermal entanglement of a two-qubit anisotropic Heisenberg $XYZ$ chain under an inhomogeneous magnetic field b is studied. It is shown that when inhomogeneity is increased to certain value, the entanglement can exhibit a larger revival than that of less values of b. The property is both true for zero temperature and a finite temperature. The results also show that the entanglement and critical temperature can be increased by increasing inhomogeneous exteral magnetic field

Unusual presentation of uterine rupture following laparoscopic myomectomy: a case report and literature review

Laparoscopic myomectomy is preferred to the laparotomy approach as the former promises a better postoperative course, with fewer complications and faster recovery. It is increasingly performed in younger women in recent years. However, although rare, uterine rupture is an important and dangerous complication. Authors report a case of 36-year-old lady who presented at 23 weeks and 4 days gestation of an in vitro fertilization (IVF) dichorionic diamniotic twin pregnancy with spontaneous uterine rupture. She underwent a laparoscopic myomectomy three year prior for a 4.5cm fundal fibroid. Her presenting symptoms include acute onset of epigastric pain. Uterine rupture was confirmed using Computed Tomography scan. She underwent an exploratory laparotomy and the placenta was found extruding from a 4cm defect on the posterior fundus along the previous myomectomy scar with active bleeding. Current literature suggests it is difficult to predict when uterine rupture may happen. Proper selection criteria for suitable cases may allow trial of labour after myomectomy to be a viable option. Potential considerations include interval between myomectomy and conception, scar integrity, method of repair, and the use of electrocoagulation. This case reports the worrying features of an early antepartum rupture presenting with atypical symptomatology. In pregnant patients presenting with abdominal pain or haemodynamic instability, it is imperative to consider uterine rupture so as to perform timely intervention. Those with a history of laparoscopic myomectomy should be considered high risk and counseled about the risk of rupture with extensive discussion about mode of delivery.

Mobile robot path navigation in static indoor environment via AOR 9-point laplacian iteration numerical technique

Mobile robot path navigation is a crucial subject in robotics research and development. The navigation efficiency of a robot correlates directly with its overall performance. With persistent technological growth, the improvement potentials for autonomous robotic remains vast. The objective of this paper is to investigate the performance of the iteration technique called Accelerated Overrelaxation 9-Point (AOR-9P) Laplacian in enabling path navigation for mobile robots. This technique is a derivation from Laplace's equation which is used to calculate the potential fields in the 2-dimensional configuration space representation of an environment. The robotic path navigations are performed in a simulation called Robot 2D Simulator, written in Delphi Project software. After obtaining the solutions generated through AOR-9P iterative technique, the Gradient Descent Search (GDS) technique is employed to determine the best path for the mobile robot to traverse on. The performance of AOR-9P is examined by comparing the number of iterations needed to complete the navigation process. Results shown that AOR-9P enabled path navigation requires the least number of iterations to complete, thus having better performance than its predecessor techniques. In the same time, the paths produced are generally smooth and unobstructed all the way towards the goal point. For future improvements, it is recommended that the Half-Sweep (HS) and Quarter-Sweep (QS) approach to be introduced on AOR-9P iteration technique to improve its performance in solving the mobile robot path navigation proble

Elastic-to-plastic crossover below the peak effect in the vortex solid of YBa2Cu3O7 single crystals

We report on transport and ac susceptibility studies below the peak effect in twinned YBa2Cu3O7 single crystals. We find that disorder generated at the peak effect can be partially inhibited by forcing vortices to move with an ac driving current. The vortex system can be additionally ordered below a well-defined temperature where elastic interactions between vortices overcome pinning-generated stress and a plastic to elastic crossover seems to occur. The combined effect of these two processes results in vortex structures with different mobilities that give place to history effects.Comment: 4 pages, 4 figures. Published in PRB Rapid Comm., February 1, 200

Real life working shift assignment problem

This study concerns about the working shift assignme\nt in an outlet of Supermarket X in Eastern Mall, Kuching. The working shift assignment needs to be solved at least once in every month. Current approval process of working shifts is too troublesome and time-consuming. Furthermore, the management staff cannot have an overview of manpower and working shift schedule. Thus, the aim of this study is to develop working shift assignment simulation and propose a working shift assignment solution. The main objective for this study is to fulfill manpower demand at minimum operation cost. Besides, the day off and meal break policy should be fulfilled accordingly. Demand based heuristic is proposed to assign working shift and the quality of the solution is evaluated by using the real data

Vortex Dynamics and Defects in Simulated Flux Flow

We present the results of molecular dynamic simulations of a two-dimensional vortex array driven by a uniform current through random pinning centers at zero temperature. We identify two types of flow of the driven array near the depinning threshold. For weak disorder the flux array contains few dislocation and moves via correlated displacements of patches of vortices in a {\it crinkle} motion. As the disorder strength increases, we observe a crossover to a spatially inhomogeneous regime of {\it plastic} flow, with a very defective vortex array and a channel-like structure of the flowing regions. The two regimes are characterized by qualitatively different spatial distribution of vortex velocities. In the crinkle regime the distribution of vortex velocities near threshold has a single maximum that shifts to larger velocities as the driving force is increased. In the plastic regime the distribution of vortex velocities near threshold has a clear bimodal structure that persists upon time-averaging the individual velocities. The bimodal structure of the velocity distribution reflects the coexistence of pinned and flowing regions and is proposed as a quantitative signature of plastic flow.Comment: 12 pages, 13 embedded PostScript figure

Test for entanglement using physically observable witness operators and positive maps

Motivated by the Peres-Horodecki criterion and the realignment criterion we develop a more powerful method to identify entangled states for any bipartite system through a universal construction of the witness operator. The method also gives a new family of positive but non-completely positive maps of arbitrary high dimensions which provide a much better test than the witness operators themselves. Moreover, we find there are two types of positive maps that can detect 2xN and 4xN bound entangled states. Since entanglement witnesses are physical observables and may be measured locally our construction could be of great significance for future experiments.Comment: 6 pages, 1 figure, revtex4 styl

Degree of entanglement for two qubits

In this paper, we present a measure to quantify the degree of entanglement for two qubits in a pure state.Comment: 5 page