A novel multiple access scheme based on slow frequency hopping multicarrier direct-sequence code division multiple access (SFH/MC DS-CDMA) is proposed and investigated, which can be rendered compatible with the existing second-generation narrowband CDMA and third-generation wideband CDMA systems. The frequency hopping patterns are controlled by a set of constant-weight codes. Consequently, mult...

Resistivity, ρ (T), of LaMnO3+δ displays between δ = 0 − 0.154 an activated behavior both above and below the paramagnetic (PM) to ferromagnetic transition temperature, TC. The relative magnetoresistance at 8 T reaches the values of – 88 % near TC and – 98 % at T ≈ 20 K. In the PM phase ρ (T) satisfies between TC ~130 − 160 K and Tv ∼ 250 − 270 K the Shklovskii – Efros-like variable-range hoppi...

We propose an improved fermion action on the lattice by adding a next nearest neightbor interaction term to the Wilson action. The proposed action is expected to approach the continuum limit more rapidly. Using the improved action, the predictions for the critical value of the hopping parameter at weak and strong coupling are given. The relationship between quark masses on the lattice and in th...

In this paper, we address the problem of designing time hopping codes for impulse radio multiple access communication systems. Time hopping techniques are first reviewed, including a new code that we proposed [2] for time hopping, and performance in terms of cyclic correlation properties are given. Advantages and disadvantages of different time hopping codes in terms of resource assignment for ...

We study a two-dimensional model for interacting colloids which is consistent with cluster states, adding a periodic corrugation potential and an external force. For different colloidal densities and different amplitude of the periodic corrugation potential we investigate the depinning from the static to the sliding regime. In the sliding states we characterize the competition between a dynamic...

In this paper we present a hybrid Physical and Medium Access Control protocol for a Wireless LAN which is designed to support both synchronous (voice) and asynchronous (data) traffic. The protocol is designed using a modified Bluetooth core and 802.11e radio access, where the voice service is supported by Bluetooth whereas data and video services are provided by 802.11e. The Bluetooth radio acc...

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In this paper we explore the mechanism of energy transfer between the single actuated DOF of a one-legged hopping robot and the remaining unactuated DOFs, during stable running. The concept of the energy transfer mechanism is laid out, after which follows an analytical study. Using this study, an initial controller is derived for the control of a simple SLIP model with friction in the leg and h...