5,457 research outputs found
Thermal analysis comparison between two random glass fibre reinforced thermoplastic matrix composites bonded by adhesives using microwaves: preliminary results
[Abstract]: This paper compares the thermal analysis of two types of random glass fibre reinforced thermoplastic matrix composites joined by adhesives using microwave energy. Fixed frequency, 2.45 GHz, microwave facility is used to join thirty three percent by weight random glass fibre reinforced polystyrene composite [PS/GF (33%)] and thirty three percent by weight random glass fibre reinforced low density polyethylene composite [LDPE/GF (33%)]. The facility used is shown in Figure 1. With a given power level, the composites were exposed to various exposure times to microwave irradiation. The primer or coupling agent used was 5-minute two-part adhesive. The heat distribution of the samples of the two types of composites was analysed and compared. The relationship between the heat distribution and the lap shear strength of the samples was also compared and discussed
Variable frequency microwave (VFM) processing facilities and application in processing thermoplastic matrix composites
Microwave processing of materials is a relatively new technology advancement alternative that provides new approaches for enhancing material properties as well as economic advantages through energy savings and accelerated product development. Factors that hinder the use of microwaves in materials processing are declining, so that prospect for the development of this technology seem to be very promising. The two mechanisms of orientation polarisation and interfacial space charge polarisation, together with dc conductivity, form the basis of high frequency heating. Clearly, advantages in utilising microwave technologies for processing materials include penetration radiation, controlled electric field distribution and selective and volumetric heating. However, the most commonly used facilities for microwave processing materials are of fixed frequency, e.g. 2.45 GHz. This paper presents a state-of-the-art review of microwave technologies, processing methods and industrial applications, using variable frequency microwave (VFM) facilities. This is a new alternative for microwave processing
Potential field methods and their inherent approaches for path planning
Path Planning is one of the vital aspects in autonomous system. In path planning, safety is important issue that
should be taken into account in order to ensure a robot reaches at the target location without collision with surrounding
obstacles. Moreover, there are important aspects that need to be addressed in path planning; computational time, optimal
path and completeness. One of the popular methods for path planning is Potential field. Potential filed method is capable to
overcome unknown scenario, taking into account the realities of the current environment of the robot motion. Two type of
forces involved in potential field method; attractive force generated by goals and repulsive force generated by obstacles.
However, this method has a major drawback due to local minima problem. This paper reviews the traditional artificial
potential field theory that has been modified with variety of algorithms based on potential field method that have been
implemented to upgrade the potential function performance in obstacle avoidance and local minima problem
Identifying an Experimental Two-State Hamiltonian to Arbitrary Accuracy
Precision control of a quantum system requires accurate determination of the
effective system Hamiltonian. We develop a method for estimating the
Hamiltonian parameters for some unknown two-state system and providing
uncertainty bounds on these parameters. This method requires only one
measurement basis and the ability to initialise the system in some arbitrary
state which is not an eigenstate of the Hamiltonian in question. The scaling of
the uncertainty is studied for large numbers of measurements and found to be
proportional to one on the square-root of the number of measurements.Comment: Minor corrections, Accepted for publication in Physical Review
Numerical study of the Jahn-Teller polaron and bipolaron
The properties of the polaron and bipolaron are explored in the 1D
Jahn-Teller model with dynamical quantum phonons. The ground-state properties
of the polaron and bipolaron are computed using a recently developed
variational method. Dynamical properties of the ground state of a polaron are
investigated by calculating the optical conductivity . Our
numerical results suggest that the Jahn-Teller and Holstein polarons are
similar. However, in the strong-coupling regime qualitative differences in
between the two models are found and discussed. The influence
of the electron-phonon coupling and the electrostatic repulsion on the
bipolaron binding energy, bipolaron masses, and correlation functions is
investigated.Comment: 9 pages including 11 figures. To appear in PR
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