Energy Loss Signals in the ALICE TRD

We present the energy loss measurements with the ALICE TRD in the $\beta\gamma$ range 1--10$^{4}$, where $\beta=v/c$ and $\gamma=1/\sqrt{1-\beta^2}$. The measurements are conducted in three different scenarios: 1) with pions and electrons from testbeams; 2) with protons, pions and electrons in proton-proton collisions at center-of-mass energy 7 TeV; 3) with muons detected in ALICE cosmic runs. In the testbeam and cosmic ray measurements, ionization energy loss (dE/dx) signal as well as ionization energy loss plus transition radiation (dE/dx+TR) signal are measured. With cosmic muons the onset of TR is observed. Signals from TeV cosmic muons are consistent with those from GeV electrons in the other measurements. Numerical descriptions of the signal spectra and the $\beta\gamma$-dependence of the most probable signals are also presented.Comment: Proceedings for the 4th Workshop on Advanced Transition Radiation Detectors for Accelerator and Space Applications, 14-16 September 2011, Bari, Ital

Simulation and Control Strategy of a Micro-Turbine Generation System for Grid Connected and Islanding Operations

AbstractThe paper adopts the method of modularized modeling, creating an electro-mechanic simulation model for a Microturbine Generation System (MTGS), including the micro-turbine engine, permanent magnetic synchronous generator, rectifier and inverter. In this paper, control strategy for grid-connected and islanding operations of a micro-turbine generation system is researched, the former adopts output voltage control strategy to maintain the output voltage of the load, and the latter adopts a dual closed-loop control algorithm based on PQ decoupling. A new control strategy to regulate the output power of MTGS based on the combination of decoupled control of output voltage and hysteresis current control is also introduced. Simulations have been done, and result proves the feasibility of the strategy

Low-complexity Noncoherent Iterative CPM Demodulator for FH Communication

In this paper, we investigate the noncoherent iterative demodulation of coded continuous phase modulation (CPM) in frequency hopped (FH) systems. In this field, one important problem is that the complexity of the optimal demodulator is prohibitive unless the number of symbols per hop duration is very small. To solve this problem, we propose a novel demodulator, which reduces the complexity by applying phase quantization and exploiting the phase rotational invariance property of CPM signals. As shown by computational complexity analysis and numerical results, the proposed demodulator approaches the performance of the optimal demodulator, and provides considerable performance improvement over the existing solutions with the same computational complexity

Diffusion in higher dimensional SYK model with complex fermions

We construct a new higher dimensional SYK model with complex fermions on bipartite lattices. As an extension of the original zero-dimensional SYK model, we focus on the one-dimension case, and similar Hamiltonian can be obtained in higher dimensions. This model has a conserved U(1) fermion number Q and a conjugate chemical potential \mu. We evaluate the thermal and charge diffusion constants via large q expansion at low temperature limit. The results show that the diffusivity depends on the ratio of free Majorana fermions to Majorana fermions with SYK interactions. The transport properties and the butterfly velocity are accordingly calculated at low temperature. The specific heat and the thermal conductivity are proportional to the temperature. The electrical resistivity also has a linear temperature dependence term.Comment: 15 pages, 1 figure, add 4 references and fix some typos in this versio

A note on the growth factor in Gaussian elimination for generalized Higham matrices

The Higham matrix is a complex symmetric matrix A=B+iC, where both B and C are real, symmetric and positive definite and $\mathrm{i}=\sqrt{-1}$ is the imaginary unit. For any Higham matrix A, Ikramov et al. showed that the growth factor in Gaussian elimination is less than 3. In this paper, based on the previous results, a new bound of the growth factor is obtained by using the maximum of the condition numbers of matrixes B and C for the generalized Higham matrix A, which strengthens this bound to 2 and proves the Higham's conjecture.Comment: 8 pages, 2 figures; Submitted to MOC on Dec. 22 201