Search

Orthogonal frequency division multiplexing (OFDM) waveform enables radar and communication functions simultaneously, which encounters low angle resolution and poor data rate for traditional single input single output (SISO) systems. To solve these problems, an integrated radar and communication system (IRCS) with multiple input multiple output (MIMO) OFDM waveform is proposed. The different limitations of radar and communication in designing such a system are investigated. Then, an optimization problem is devised to obtain suitable system parameters, including the number of subcarriers, subcarrier spacing, number of symbols, pulse repetition frequency (PRF) and length of cyclic prefix (CP). Finally, to satisfy the requirements of both radar and communication, the IRCS parameters are derived in three typical cases. Several numerical results are presented to illustrate the demands of radar and communication, inconsistent or consistent, for the IRCS parameters and the superiority of the proposed system. [ABSTRACT FROM AUTHOR]

On the basis of the ZINDO program, we have designed a program to calculate the first-order hyperpolarizability βijk and βμ according to the sum-over-states (SOS) expression. The first-order hyperpolarizability of 4-(dicyanomethylene)-2,6-bis-(2'-thiophene-vinyl)-pyran derivatives were studied. The calculated results were that the 4-(dicyanomethylene)-2,6-bis-(2'-thiophene-vinyl)-pyran derivatives exhibit good nonlinearity with their β0 values, which are slightly less than that of the corresponding 2,6-bis-styryl-4-(dicyanomethylene)-pyran derivatives. It does not agree with the auxiliary donor–acceptor effects theory. The 4-(dicyanomethylene)-2,6-bis-(2'-thiophene-vinyl)-pyran derivatives, having two low-lying electronic excited states that contribute to the molecular hyperpolarizability in an additive manner, are good candidates as chromophores due to their high nonlinearities and good thermal stability. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 82: 65–72, 2001

Abstract: The power-time curves of bacterial growth at different temperatures were determined by using the 2277 Thermal Activity Monitor (Sweden). From these curves, the growth rate constant (μ) and activation energy (E a) were calculated. According to the transition state theory of reaction dynamics, the activation entropy (ΔS≠), activation Gibbs free energy (ΔG≠) and equilibrium constant (K ≠ ) of the activation state could be calculated. These results permitted thermodynamic analysis of the bacterial growth metabolism.