Torque density maximization of vernier machine by using series compensation

This paper deals with the design of SPM vernier machine with high slots/pole/phase q, to get higher torque density as well as improved power factor by applying the concept of series compensation. The torque density of a vernier machine can be enhanced by increasing the number of slots/pole/phase q, but as q increases the drastic increase in the reactance makes the power factor even worse. Therefore, it is general to choose low q, even if higher torque can be obtained with higher q. In this study, the idea of series compensation is applied to get vernier machine with high q without the low power factor problem. Series compensation is performed by supplying the desired reactive power to the machine from an additional inverter with a floating capacitor. To validate the theoretical analyses, three SPM vernier machines with different q (1 ∼ 3) are designed and then analyzed by using FEM.

Integrating Software Defined Radio with USRP

The USRP1 is the original Universal Software Radio Peripheral hardware (USRP) that provides entry-level RF processing capability. Its primary purpose is to provide flexible software defined radio development capability at a low price. You can control the frequency you receive and transmit by installing different daughter-boards. The authors' USRP model had been configured to receive a signal from local radio stations in the DC, Maryland metropolitan area with the BasicRX model daughterboard. The programmable USRP was running python block code implemented in the GNU Radio Companion (GRC) on Ubuntu OS. With proper parameters and sinks the authors were able to tune into the radio signal, record the signal and extract the in-phase (I) and quadrature phase (Q) data and plot the phase and magnitude of the signal. Using the terminal along with proper MATLAB and Octave code, they were able to read the I/Q data and look at the Fast Fourier Transform (FFT) plot along with the I/Q data. With the proper equations, you could determine not only the direction of arrival, but one would also be able to calculate the distance from the receiver to the exact location where the signal is being transmitted. The purpose of doing this experiment was to gain experience in signal processing and receive hands on experience with the USRP and potentially add a tracking system to the authors' model for further experiments.

Effect of Fe on microstructures and mechanical properties of an Al–Mg–Si–Cu–Cr–Zr alloy prepared by low frequency electromagnetic casting

The effects of different Fe contents (0.168, 0.356 and 0.601 wt%) on microstructures and mechanical properties of the Al–1.6Mg–1.2Si–1.1Cu–0.15Cr–0.15Zr (all in wt%) alloys prepared by low frequency electromagnetic casting process were investigated in the process of solidification, hot extrusion, solid solution and aging treatments. The results show that the increase of Fe content promotes the formation of feathery grains in the process of solidification and the precipitation of another important strengthening phase Q′ with small size. Additionally, it also results in no recrystallization even after solid solution at a high temperature of 550 °C, which is because of the increase number of elliptical shaped and fine DO22-Al3Zr dispersoids (∼70 nm long and ∼35 nm wide) and the spherical or elliptical shaped Fe-containing phases. When Fe content of the alloy increases to 0.356 wt%, both the ultimate tensile strength and yield strength of the alloy-T6 increase by more than 60 MPa and with little cost of ductility.

Comparison of RZ-OOK and RZ-DPSK Optimal Performance

Using the Differential Phase Q (DP-Q) and the traditional Q factor, performance comparison of RZ-OOK and RZ-DPSK in dense OTDM-WDM systems is obtained in this chapter. When signal pulse widths and optical filter bandwidths are optimized, there is no upper limit to WDM channel bit rate (BR) in the purely linear back-to-back configuration. Here, RZ-DPSK performed increasingly better than RZ-OOK in higher spectral density with Q gain increasing from 3 dB to 5 dB. In the nonlinear point-to-point configuration, higher BR leads to increased performance penalties for both RZ-DPSK and RZ-OOK, while RZ-DPSK still outperforms RZ-OOK by up to 4 dB. The results obtained correlate with conventional results, indicating the potential of the DP-Q as a performance evaluation tool in numerical simulations.

MODIFIED GRAVITY THEORY DUE TO POSITIVE AS WELL AS NEGATIVE CURVATURE INDUCED ACCELERATION

We formulate a modified gravity theory that eliminates the need for dark energy and is stable for a Lagrangian containing R, R2 as well as 1/R terms (i.e. nonlinear contributions of the Ricci curvature with a non-analytic model of f(R) at R = 0) without considering any matter-dominated era. The terms with positive powers (1, 2) of the curvature support the inflationary epoch while the terms with negative power (-1) serves as effective dark energy, supporting current cosmic acceleration. We present a few analytical solutions of evolution equation for the deceleration parameter q as a function of Hubble parameter H and time t; specially in one solution, the universe evolves continuously from q = 1 (a radiation-dominated epoch) to q = -1/2 (dark-energy-dominated late-time accelerating phase) when the universe is sufficiently old. The solution is supported by numerical results. The transition from the decelerated (q > 0) to the accelerated phase (q < 0) of expansion takes place smoothly without having to resort to a study of asymptotic behavior.