The existence of long-lived nuclear spin states in four-spin systems is explored by solution-state NMR experiments. Long-lived states are proved to exist in three different natural product molecules, each containing either a AA'BB' or a AA'XX' proton spin system. The measured state lifetimes are between four and eight times the spin-lattice relaxation time constants.

The PEP-I1 high energy ring (HER) vacuum chamber consists of a copper tube with periodically spaced p u m p ing slots. The impedance of the vacuum chamber due to the slots is analyzed. Both narrow-band and broadband impedances are considered as well as longitudinal and transverse components thereof. It is found that although the broad-band impedance is tolerable, the narrow-band impedance may e...

This paper presents a switched-beam antenna using circumferential-slot on a concentric sectoral cylindrical cavity excited by coupling slots to operate at 5.8 GHz. The advantages of this antenna are conformal structure, high directivity and capable of switched-beam pattern in six directions. The antenna design starts from a single sector which is capable of switching between radiating and non-r...

It is shown that a Partitioned Optical Passive Stars (POPS) network with g groups and d processors per group can route any permutation among the n = dg processors in one slot when d = 1 and 2dd=ge slots when d > 1. The number of slots used is optimal in the worst case, and is at most the double of the optimum for all permutations π such that π(i) 6= i, for all i.

Folded slots are attractive for active arrays because of their broad bandwidth and simplicity. They have been used recently in a quasi-optical amplifier array. However, little is known about these antennas on thin substrates. The finite-difference time-domain (FDTD) method is applied to the analysis of cpw-fed folded-slot antennas. This paper compares the theoretical results and measured data a...

In this paper, we present a TDMA based multiple access technique for ATM over satellite. We consider an scenario where a large number of remote stations are connected to the ATM cloud via satellite. We focus on performance evaluation for CBR, VBR and ABR traffic with markovian analysis and simulation. We calculate equivalent bandwidth for VBR traffic in order to gain statistical multiplexing, w...

We present a dialogue manager that is able to handle multiple domains simultaneously. Our dialogue manager consists of five modules, one of which, the Task Manager, deserves special attention. Each domain is represented by a frame, which is in turn composed by slots and rules. Slots define domain data relationships, and rules define the system’s behavior. The use of frames allowed the remaining...