Diffraction by a dielectric wedge with the neumann expansion of correction currents on interfaces

A new representation of fringe currents, which corrects the physical optics approximation for edge diffraction by a dielectric wedge, is obtained. In comparison with the multipole expansion at an edge, the proposed Neumann expansion of correction currents along the dielectric interfaces satisfies the edge condition at the edge and provides fast convergence after finite truncation of expansion coefficients.     

Synthesis,molecular and optical characterization of polycarbonates containing azobenzene side‐chains

In this study, we report the synthesis and holographic characterization of polycarbonates containing an azobenzene group in their side‐chains. The polycarbonate (DR‐PC) was synthesized by the polyaddition reaction of Disperse Red 19 (DR 19) and carbon dioxide in N‐methyl‐2‐pyrrolidone for 24 h in air, and we investigated the mechanism in the presence of potassium carbonate. The film of polycarbonate was obtained by casting onto a slide glass in N,N‐dimethylformamide. The diffraction efficiency of the polycarbonate film was measured as a function of time and intensity of the induced laser. Independently of the intensity of the writing beam, the maximum diffraction efficiency in all DR‐PC films reached about 0.25%. Copyright © 2006 Society of Chemical Industry     

Syntheses and properties of polyurethanes containing side‐chain azobenzene groups

Polymers containing azobenzene groups have the characteristic reaction of photo‐induced cis–trans isomerism. The study of new materials for optical information storage has prompted making use of these photo‐isomerizations. In this study, we report the syntheses and properties of four different polyurethanes (DR‐PUns) containing azobenzene groups in the side‐chains. The structurally similar polyurethanes (DR‐PUns) were synthesized by the polycondensation reaction of Disperse Red 19 (DR 19) and four different diisocyanates in dimethylformamide. By introducing of DR 19 into the polymer, we obtained polymers containing a photochromic group in the side‐chain. The weight‐average molecular weights of the DR‐PUns were in the range 5500–12 900. The T_gs of the DR‐PUns range from 119.5 °C to 157.0 °C, depending on the structure of the diisocyanate. Optical properties and solubilities of the polyurethanes were compared. The diffraction efficiencies of films were measured as a function of the reaction time. Typically, the diffraction efficiencies of the DR‐PU1 film prepared from toluene 2,4‐diisocyanate were observed up to a level of 0.25%. For the DR‐PU1 film, the effect of the intensity of the induced laser beam on the diffraction efficiency is also discussed. © 2003 Society of Chemical Industry     

Analytical Relationships for Designing Rectangular Drip Irrigation Units

Approximate analytical expressions were obtained that relate uniformity indices of water distribution in rectangular drip irrigation units as a function of the variables that define that unit: lengths and diameters of laterals and submain, spacing of emitters and laterals, ground slopes, parameters of the emitter discharge equation, and equivalent lengths characterizing local losses. The proposed expressions offer greater precision than might be needed in irrigation practice. They do not require iterative calculations and improve the procedures normally used. They may be useful in the design of drip irrigation units and in their evaluation and management. An example of their application is offered. The proposed relationships simplify studies of the sensitivity of variables involved in optimum hydraulic design. Users are thus allowed a rational understanding of their influence, improving that which can be gained from computer programs. Graphs obtained with the mentioned expressions are also offered. They can be of interest, although their use is not treated specifically in this paper.     

Improved hierarchical search block matching algorithm by usingmultiple motion vector candidates

The authors describe a hierarchical search block matching algorithm capable of handling large motion in real time motion estimation for existing video compression standards. The algorithm uses multiple motion vector candidates based on an interframe difference measure and a spatial motion-field correlation, respectively. In MPEG-2 application, the encoder adopting the proposed algorithm provides nearly the same performance as the conventional encoder adopting the full search block matching algorithm, with only 0.9% computational complexity for motion estimation     

A Joint Scheme of AGC and Gain/Phase Mismatch Compensation for QPSK DCR

This paper presents a simple gain/phase blind compensation algorithm with an automatic gain control (AGC) function for the adoption of the AGC function and compensation for gain/phase imbalances in quadrature phase shift keying (QPSK) direct conversion receivers (DCRs). The AGC function is interactively operated with the compensation algorithm for gain/phase imbalances. By detecting the gain sum and difference values between the I‐channel and Q‐channel, the combined AGC and gain imbalance compensation algorithm provides a simpler DCR architecture.     

True three-dimensional cone-beam reconstruction (TTCR) algorithm

A true three-dimensional cone-beam reconstruction (TTCR) algorithm for direct volume image reconstruction from 2-D cone-beam projections is developed for the complete sphere geometry. The algorithm is derived from the parallel-beam true three-dimensional reconstruction (TTR) algorithm and is based on the modified filtered backprojection technique, which uses a set of 2-D space-invariant filters. The proposed algorithm proved to be superior in spatial resolution to the parallel-beam TTR algorithm and to offer better computational efficiency.     

A parametric quality model to evaluate the performance of tele-operated driving services over 5G networks

Multimedia Tools and Applications - We have developed a parametric model to quantify the Key Quality Indicators which affect video-based Tele-operated Driving (ToD) over a mobile network, as well...     

Load balancing in a heterogeneous world: CPU-Xeon Phi co-execution of data-parallel kernels

Heterogeneous systems composed by a CPU and a set of different hardware accelerators are very compelling thanks to their excellent performance and energy consumption features. One of the most important problems of those systems is the workload distribution among their devices. This paper describes an extension of the Maat library to allow the co-execution of a data-parallel OpenCL kernel on a heterogeneous system composed by a CPU and an Intel Xeon Phi. Maat provides an abstract view of the heterogeneous system as well as set of load balancing algorithms to squeeze the performance out of the node. It automatically performs the data partition and distribution among the devices, generates the kernels and efficiently merges the partial outputs together. Experimental results show that this approach always outperforms the baseline with only a Xeon Phi, giving excellent performance and energy efficiency. Furthermore, it is essential to select the right load balancing algorithm because it has a huge impact in the system performance and energy consumption.

     

Toward a boundary regional control problem for Boolean cellular automata

An important question to be addressed regarding system control on a time interval [0, T] is whether some particular target state in the configuration space is reachable from a given initial state. When the target of interest refers only to a portion of the spatial domain, we speak about regional analysis. Cellular automata approach have been recently promoted for the study of control problems on spatially extended systems for which the classical approaches cannot be used. An interesting problem concerns the situation where the subregion of interest is not interior to the domain but a portion of its boundary . In this paper we address the problem of regional controllability of cellular automata via boundary actions, i.e., we investigate the characteristics of a cellular automaton so that it can be controlled inside a given region only acting on the value of sites at its boundaries.