Data security becomes one of the things that need to be considered. The Sum of Product (SOP) Encryption is one of simple algorithm. The SOP encryption is not a public-key system to encrypt data. it is almost unbreakab...
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In industrial automation and robotic applications, direct-drive motors represent a suitable solution to friction and backlash problems typical of mechanical reduction gears. Variable reluctance (VR) motors are well su...
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In industrial automation and robotic applications, direct-drive motors represent a suitable solution to friction and backlash problems typical of mechanical reduction gears. Variable reluctance (VR) motors are well suited for direct-drive implementation but, because of the strongly nonlinear electromechanical characteristics, these motors are traditionally designed as stepper motors. The main aim of the work described in the paper is the design of a high-performance ripple-free dynamic torque controller for a VR motor, intended for trajectory tracking in robotic applications. An original modeling approach is investigated in order to simplify the design of the high-performance torque controller. Model structure and parameter estimation techniques are presented. Different approaches to the overall torque controller design problem are also discussed and the solution adopted is illustrated. A cascade controller structure is considered. It consists of a feedforward nonlinear torque compensator, cascaded to a nonlinear flux or current closed-loop controller. The feedforward compensator is carefully considered and optimization techniques are used for its design. Two optimization criteria are proposed: the first minimizes copper losses, whereas the second minimizes the maximum value of the motor-feeding voltage. Although developed for a specific commercial motor, the proposed modeling and optimization strategies can be used for other VR motors with magnetically decoupled phases, both rotating and linear. Laboratory experiments for model validation and preliminary simulation results of the overall torque control system are presented.
The singular stress field around a sharp notch tip is expressed as a sum of two independent fields: a symmetric field with a stress singularity 1/tau(1-lambda 1) and a skew-symmetric field with a stress singularity 1/...
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The singular stress field around a sharp notch tip is expressed as a sum of two independent fields: a symmetric field with a stress singularity 1/tau(1-lambda 1) and a skew-symmetric field with a stress singularity 1/tau(1-lambda 2). The intensities of the symmetric and skew-symmetric singular stress fields are defined in terms of constants K-I and K-II, respectively. In this study, a plane problem of a strip with single or double edge notches under tension or in-plane bending is considered. The bisector of the notch may be inclined to the edge, so that the two singular stress fields with different singularities may be created simultaneously at the notch tip. The body force method is used to calculate the stress intensity factors K-I and K-II. In numerical analysis, basic density functions of the body forces are introduced to characterize the stress singularity at the notch tip. The advantages of this technique are the high accuracy of results, due to the smoothness of the unknown weight functions, and the presence of the direct relation between the values of K-I and K-II and the values of unknown weight functions. The stress intensity factors are systematically calculated for the various geometrical conditions.
Rate adaptation in wireless LANs is to select the most suitable transmission rate automatically according to channel condition. If the channel condition is good, a station can choose a higher transmission rate, otherw...
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Current research efforts are being directed to commit with the long-term view of self-management properties for wireless telecommunications. One of the key approaches that have been recognized as an enabler of such a ...
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An optical fiber multi-function device consisting of a single gradient-index-rod lens and a multi-facet blazed reflection grating is proposed to simultaneously realize functions of wavelength demultiplexing and optica...
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An optical fiber multi-function device consisting of a single gradient-index-rod lens and a multi-facet blazed reflection grating is proposed to simultaneously realize functions of wavelength demultiplexing and optical signal distribution in a multimode optical fiber transmission system. We analyzed the demultiplexing characteristics and the tolerance of optical components using the ray trace method. This device can realize not only low loss optical signal distribution but also offers improved demultiplexing characteristics in comparison with the previously proposed demultiplexer-multiposition switch. The following characteristics are expected from the design using commercially available optical components: a working band of 0.64-0.88 mu m, channel separation of 34-36 nm, 3 dB bandwidth of 27-28 nm, channel cross-talk of less than -40 dB and minimum excess insertion loss of 0.9-2.1 dB.
Many approaches for converting keyword queries to formal query languages are presented for natural language interfaces to ontologies. Some approaches present fixed formal query templates, so they lack in providing sup...
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An algorithm for finding the unequal error protection (UEP) capability of a q-ary image of a low-rate q(m)-ary cyclic code is presented by combining its concatenated structure with the UEP capability of concatenated c...
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An algorithm for finding the unequal error protection (UEP) capability of a q-ary image of a low-rate q(m)-ary cyclic code is presented by combining its concatenated structure with the UEP capability of concatenated codes. The results are independent of a choice of a basis to be used for expanding an element over GF (q(m)) into GF (q). A table of the UEP capability of binary images of low-rate Reed-Solomon codes over GF(2(6)) is given. It is shown that the encoding and decoding algorithms for superimposed concatenated codes can be applied to a q-ary image as a linear UEP code.
There is now vigorous research on the intelligent transport system (ITS), and also on the advanced cruise-assist highway system (AHS), which is one of the ITS components. An element of the AHS is the system that extra...
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One of the problems in wireless mesh networks includes the HOL (Head of Line) blocking at relay nodes. To overcome that problem, packet scheduling schemes using the MRTS (Multicast RTS) frame, an extension of the RTS ...
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