Noise filtering in binary pictures by combinatorial techniques

Filtering of noise in binary pictures includes both the filling of spurious gaps and the elimination of spurious connections. This paper describes a method which performs these operations by examining pairs of boundary points of the various objects in the picture. The current implementation uses only distance criteria, but it can be extended by taking into account local shape information.     

Hardware Simulator Design for MIMO Propagation Channel on Shipboard at 2.2 GHz

A wireless communication system can be tested either in actual conditions or with a hardware simulator reproducing actual conditions. With a hardware simulator it is possible to freely simulate a desired radio channel, making it possible to test “on table” mobile radio equipments. This paper presents new architectures for the digital block of a hardware simulator of MIMO propagation channels. This simulator can be used for LTE and WLAN IEEE 802.11ac applications, in indoor and outdoor environments. However, in this paper, specific architectures of the digital block of the simulator for shipboard environment are presented. A hardware simulator must reproduce the behavior of the radio propagation channel. Thus, a measurements campaign has been conducted to obtain the impulse responses of the shipboard channel using a channel sounder designed and realized at IETR. After the presentation of the channel sounder, the channel impulse responses are described and implemented. Then, the new architectures of the digital block of the hardware simulator, implemented on a Xilinx Virtex-IV FPGA are presented. The accuracy, the occupation on the FPGA and the latency of the architectures are analyzed.     

Optimization methods applied for solving the short-term hydrothermal coordination problem

Short-term hydrothermal coordination (STHTC) is a very complicated optimization problem. It is a dynamic large-scale non-linear problem and requires solving unit commitment and economic power load dispatch problems. From this perspective, many successful and powerful optimization methods and algorithms have been employed to solve this problem. These optimization methodologies and techniques are widely diverse and have been the subject of ongoing enhancements over the years. This paper presents a survey of literature on the various optimization methods applied to solve the STHTC problem. A review and a methodology-based classification of most of the publications on the topic are presented.     

A method for interpolating on manifolds structural dynamics reduced‐order models

A rigorous method for interpolating a set of parameterized linear structural dynamics reduced‐order models (ROMs) is presented. By design, this method does not operate on the underlying set of parameterized full‐order models. Hence, it is amenable to an online real‐time implementation. It is based on mapping appropriately the ROM data onto a tangent space to the manifold of symmetric positive‐definite matrices, interpolating the mapped data in this space and mapping back the result to the aforementioned manifold. Algorithms for computing the forward and backward mappings are offered for the case where the ROMs are derived from a general Galerkin projection method and the case where they are constructed from modal reduction. The proposed interpolation method is illustrated with applications ranging from the fast dynamic characterization of a parameterized structural model to the fast evaluation of its response to a given input. In all cases, good accuracy is demonstrated at real‐time processing speeds. Copyright © 2009 John Wiley & Sons, Ltd.     

Wear resistant composite coatings

In the search for wear resistant coatings, nanolaminated composite films composed of alternating metallic and ceramic layers, namely, Al/Al₂O₃ and Ti/TiN were produced using radio frequency magnetron sputtering. The metal layer thickness in the as-sputtered films of Al/Al₂O₃ ranged from 70 to 500 nm, and 150 to 450 nm in Ti/TiN. The non-metals (Al₂O₃ and TiN) layer thicknesses ranged from 10 to 40 nm and total film thicknesses of 10–15 µm. All coatings were characterized and tested for their tribological properties. Friction and wear tests were performed under non-lubricated sliding conditions using a pin-on-disc type tribometer. The coefficient of friction of the composite coatings tested, against a stainless steel pin, varied with the sliding distance. At the early stages of sliding the coefficient of friction rose to a peak, followed by a decrease to a steady-state value. Wear rates and coefficients of friction were related to the hardness and to the structure refinement of the coatings.     

The effects of Ni3Al binder content on the electrochemical response of melt-infiltration processed TiC–Ni3Al cermets

TiC–Ni₃Al samples were successfully fabricated with varying amounts of the Ni₃Al intermetallic binder (alloy IC-50), ranging from 10 to 40?wt-%, through a simple melt-infiltration method. Each sample was then tested to determine the degree of resistance of that composition to electrochemical corrosion in an aqueous solution containing 3.5?wt-% NaCl, using a range of testing procedures including open-circuit potential, potentiodynamic polarisation and cyclic polarisation. Results indicate that the lowest binder content results in greater potential to resist corrosion. It is demonstrated that the Ni₃Al binder undergoes dissolution for the examined conditions, which was confirmed through the high amount of Al and Ni in the electrolyte solutions following testing. It was also confirmed from the electrochemical experiments and the SEM that localised corrosion was visible.     

Catalytic coprocessing of coal and petroleum residues with waste plastics to produce transportation fuels

Coprocessing reactions with waste plastics, petroleum residues and coal were performed to determine the individual and blended behavior of these materials using lower pressure and cheaper catalysts. The plastic used in this study was polypropylene. The thermodegradative behavior of polypropylene (PP) and PP/petroleum residues/coal blends were investigated in the presence of solid hydrocracking (HC) catalysts. A comparison among various catalysts has been performed on the basis of observed temperatures. The higher temperatures of initial weight loss of PP shifted to lower values by the addition of petroleum residues and coal. The catalysts were also tested in a fixed-bed micro reactor for the pyrolysis of polypropylene, petroleum residues and coal, alone and blended together in nitrogen and hydrogen atmosphere. High yields of liquid fuels in the boiling range 100-480 °C and gases were obtained along with a small amount of heavy oils and insoluble material such as gums and coke. The results obtained on the coprocessing of polypropylene with coal and petroleum residues are very encouraging as this method appears to be quite feasible to convert plastic materials into liquefied coal products and to upgrade the petroleum residues and waste plastics.     

Comminution limit (CL) of particles and possible implications for pumped storage reservoirs

Comminution (fragmentation) of solid particles is important in a range of technologies. An interesting effect is the so-called comminution limit (CL), which is effectively a brittle/ductile transition. Above the CL particles fail by fracture. However, as particle size decreases the amount of stored energy in the particle also decreases and eventually there is no longer sufficient stored energy in the particle to propagate a crack and the particle flows plastically. The CL depends on the hardness, H, and the toughness, K _Ic. In mountainous countries, two-reservoir systems are used to generate and store power. When power is needed, water runs through the turbines to the lower reservoir. If there is excess power, water is pumped to the upper reservoir. This recycling of liquid through the turbines can break up entrained particles. Previous work in this area has been primarily concerned with sedimentation of the particles. The research reported in this paper uses the CL to calculate the particle sizes produced for different materials including different rock types. Interestingly, the particle sizes predicted mainly fall in the range where they sediment near the upper water surface. In such cases, the surface layers become opaque to sunlight and plant and animal life will be affected. It is suggested that the CL provides additional information which would assist research in this area. Where H and K _Ic are not known for a particular rock type they should be measured.