Fuzzy Petri net (FPN) provides an extremely competent basis for the implementation of computing reasoning processes and the modeling of systems with uncertainty. This paper reviews recent developments of the FPN and its industrial applications. Several important aspects of FPN's background, history and formalisms are discussed, including the reasoning algorithm and relevant industrial applications; after which we present our conclusions and suggestions for future research.

Fuzzy Petri nets and industrial applications: a review

Robots are increasingly assisting humans in performing various tasks. Like special agents with elite skills, they can venture to distant locations and adverse environments, such as the deep sea and outer space. Micro/nanobots can also act as intrabody agents for healthcare applications. Self-healing materials that can autonomously perform repair functions are useful to address the unpredictability of the environment and the increasing drive toward the autonomous operation. Having self-healable robotic materials can potentially reduce costs, electronic wastes, and improve a robot endowed with such materials longevity. This review aims to serve as a roadmap driven by past advances and inspire future cross-disciplinary research in robotic materials and electronics. By first charting the history of self-healing materials, new avenues are provided to classify the various self-healing materials proposed over several decades. The materials and strategies for self-healing in robotics and stretchable electronics are also reviewed and discussed. It is believed that this article encourages further innovation in this exciting and emerging branch in robotics interfacing with material science and electronics.

Progress and Roadmap for Intelligent Self-Healing Materials in Autonomous Robotics

Probability y statistics

This paper describes a computational study of the hydrodynamics of a ray-inspired underwater vehicle conducted concurrently with experimental measurementsHigh-resolution stereo-videos of the vehicle’s fin motions during steady swimming are obtained and used as a foundation for developing a high fidelity geometrical model of the oscillatory finA Cartesian grid based immersed boundary solver is used to examine the flow fields produced due to these complex artificial pectoral fin kinematicsSimulations are carried out at a smaller Reynolds number in order to examine the hydrodynamic performance and understand the resultant wake topologyResults show that the vehicle’s fins experience large spanwise inflexion of the distal part as well as moderate chordwise pitching during the oscillatory motionMost thrust force is generated by the distal part of the fin,and it is highly correlated with the spanwise inflexionTwo sets of inter-connected vortex rings are observed in the wake right behind each finThose vortex rings induce strong backward flow jets which are mainly responsible for the fin thrust generation

Thrust producing mechanisms in ray-inspired underwater vehicle propulsion

Supporting resilient conceptual design using functional decomposition and conflict resolution

In this paper, a novel decision based median (DBM) filter for enhancing MR images has been proposed. The method is based on eliminating impulse noise from MR images. A median-based method to remove impulse noise from digital MR images has been developed. Each pixel is leveled from black to white like gray-level. The method is adjusted in order to decide whether the median operation can be applied on a pixel. The main deficiency in conventional median filter approaches is that all pixels are filtered with no concern about healthy pixels. In this research, to suppress this deficiency, noisy pixels are initially detected, and then the filtering operation is applied on them. The proposed decision method (DM) is simple and leads to fast filtering. The results are more accurate than other conventional filters. Moreover, DM adjusts itself based on the conditions of local detections. In other words, DM operation on detecting a pixel as a noise depends on the previous decision. As a considerable advantage, some unnecessary median operations are eliminated and the number of median operations reduces drastically by using DM. Decision method leads to more acceptable results in scenarios with high noise density. Furthermore, the proposed method reduces the probability of detecting noise-free pixels as noisy pixels and vice versa.

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An enhanced median filter for removing noise from MR images

Synthesis a Petri net based control model for a FMS cell

Propulsive capability of manta rays' flapping pectoral fins has inspired many to incorporate these fins as propulsive mechanisms for autonomous underwater vehicles. In particular, geometrical factors such as sweep angle have been postulated as being influential to these fins' propulsive capability, specifically their thrust generation. Although effects of sweep angle on static/flapping wings of aircrafts/drones have been widely studied, little has been done for underwater conditions. Furthermore, the findings from air studies may not be relatable to the underwater studies on pectoral fins because of the different Reynolds number (compared to the flapping wings) and force generation mechanism (compared to the static wings). This paper aims to establish a relationship between the sweep angle and thrust generation. An experiment was conducted to measure the thrust generated by 40 fins in a water channel under freestream and still water conditions for chord Reynolds number between 2.2 × 104 and 8.2 × 104. The fins were of five different sweep angles (0 deg, 10 deg, 20 deg, 30 deg, and 40 deg) that were incorporated into eight base designs of different flexibility characteristics. The results showed that the sweep angle (within the range considered) may have no significant influence on these fins' thrust generation, implying no significant effects on thrust under uniform flow condition and on the maximum possible thrust under still water. Overall, it can be concluded that sweep angle may not be a determinant of thrust generation for flapping pectoral fins. This knowledge can ease the decision-making process of design of robots propeled by these fins.

A relationship between sweep angle of flapping pectoral fins and thrust generation

Multibody models of scoliotic spine have shown great promise in planning scoliosis surgery by providing predictive information concerning the surgery outcome. To provide good predictive information, it is important that the kinematic models underlying the movement of the spine models would be personalized to give good estimates of the spine in different positions, which is lacking in the existing literature. This paper aims to develop a patient-specific multibody kinematic model of the scoliotic spine to represent its movement in frontal plane of the human body. The model is an open-chain mechanism comprising rigid links interconnected with rotary joints. To represent the movement, the mechanism lays on the spine curve and estimates the curve and the location and orientation of vertebrae. To personalize the mechanism for a patient, a minimization problem is defined to give the number of the links and their length by using X-rays of different spine positions. The feasibility and capabilities of our patient-specific model are tested by using the data from preoperative X-rays of five positions of 10 AIS (adolescent idiopathic scoliosis) patients; three of the X-rays are routine in scoliosis standard care. The mechanism is personalized to each patient by using the three routine X-rays, and it is used to estimate all the five positions. Root-mean-square-errors (RMSE) of the curve, location, and orientation are 2e–5 mm, 0.27 mm, and 0.25°, respectively. The small RMSEs imply that our kinematic model is capable of estimating the scoliotic spine positions in the frontal plane and thus of describing the scoliotic spine movement in this plane. Our personalization using X-rays of three spine positions helps to set better values for the kinematic parameters (such as the length of the links) for more accurate estimates of the spine in the frontal plane.

A patient-specific multibody kinematic model for representation of the scoliotic spine movement in frontal plane of the human body

Manta ray's pectoral fins have been a great source of inspiration for propulsive mechanism of autonomous underwater vehicles, due to their propulsive capability. The geometry (shape) and flexibility factors of these fins have been hypothesized to be determinants of the propulsive capability of the fins in terms of thrust generation. In particular, the sweep angle factor has been omitted from previous studies, where it has been commonly set to about 30 degrees. This paper investigates the effects of sweep angle on thrust generation of oscillatory pectoral fins. Forty different fins were designed and fabricated to be experimented in a water channel, which involved measurement of thrust generated by the fins. The experiment was conducted under free stream (0.5 m/s) and still water conditions. Five different sweep angles (0, 10, 20, 30, 40 degrees) were incorporated into eight base designs of different flexibility characteristics to make up the 40 fins. To consider only sweep angle, other geometrical factors were not varied. Within the range of the sweep angle considered, the experimental results showed that sweep angle has no significant influence on the fins' thrust generation, under both free stream and still water conditions. Overall, it can be concluded that sweep angle may not be a determinant of oscillatory pectoral fins' thrust generation.

Soheil Arastehfar

Papers

An enhanced median filter for removing noise from MR images

Synthesis a Petri net based control model for a FMS cell

A relationship between sweep angle of flapping pectoral fins and thrust generation

A patient-specific multibody kinematic model for representation of the scoliotic spine movement in frontal plane of the human body

Study of sweep angle effect on thrust generation of oscillatory pectoral fins