Orthogonal on-off BPSK: a convenient signaling scheme for near-far resistant detection in DS/CDMA

This paper proposes a convenient signaling scheme-orthogonal on-off BPSK (O3BPSK)-for near-far (NF) resistant detection in asynchronous direct-sequence code-division multiple-access (DS/CDMA) systems (uplink). The temporally adjacent bits from different users in the received signals are decoupled by using the on-off signaling, and the original data rate is maintained with no increase in transmission rate by adopting an orthogonal structure. The detector at the receiver is a one-shot linear decorrelating detector, which depends upon neither hard decision nor specific channel coding. The application of O3 strategy to the differentially encoded BPSK (D-BPSK) sequences is also presented. Finally, some computer simulations are shown to confirm the theoretical analysis.

The decomposition of some RDX and HMX based materials in the one dimensional time to explosion apparatus. Part 2. Estimating the violence of the cook-off event

Various methods of assessment have been applied to the One Dimensional Time to Explosion (ODTX) apparatus and experiments with the aim of allowing an estimate of the comparative violence of the explosion event to be made. Non-mechanical methods used were a simple visual inspection, measuring the increase in the void volume of the anvils following an explosion and measuring the velocity of the sound produced by the explosion over 1 metre. Mechanical methods used included monitoring piezo-electric devices inserted in the frame of the machine and measuring the rotational velocity of a rotating bar placed on the top of the anvils after it had been displaced by the shock wave. This last method, which resembles original Hopkinson Bar experiments, seemed the easiest to apply and analyse, giving relative rankings of violence and the possibility of the calculation of a “detonation” pressure.

Warding off an epitaph: had I a thousand lives

Essay considering the representation of Irish history and its commemoration in Medbh McGuckian's poetry collection 'Had I a Thousand Lives'.

Dimensionalising on- and off-line brands' composite equity

This paper approaches the subject of brand equity measurement on and offline. The existing body of research knowledge on brand equity measurement has derived from classical contexts; however, the majority of today's brands prosper simultaneously online and offline. Since branding on the Web needs to address the unique characteristics of computer-mediated environments, it was posited that classical measures of brand equity were inadequate for this category of brands. Aaker's guidelines for building a brand equity measurement system were thus followed and his brand equity ten was employed as a point of departure. The main challenge was complementing traditional measures of brand equity with new measures pertinent to the Web. Following 16 semi-structured interviews with experts, ten additional measures were identified.

Vehicle-driver communication using off-the-shelf transceivers

Almost all modern cars can be controlled remotely using a personal communicator (keyfob). However, the degree of interaction between currently available personal communicators and cars is very limited. The communication link is unidirectional and the communication range is limited to a few dozen meters. However, there are many interesting applications that could be supported if a keyfob would be able to support energy efficient bidirectional longer range communication. In this paper we investigate off-the-shelf transceivers in terms of their usability for bidirectional longer range communication. Our evaluation results show that existing transceivers can generally support the required communication ranges but that links tend to be very unreliable. This high unreliability must be handled in an energy efficient way by the keyfob to car communication protocol in order to make off-the-shelf transceivers a viable solution.

A simple framework for assessing the trade-off between the climate impact of aviation carbon dioxide emissions and contrails for a single flight

Persistent contrails are an important climate impact of aviation which could potentially be reduced by re-routing aircraft to avoid contrailing; however this generally increases both the flight length and its corresponding CO emissions. Here, we provide a simple framework to assess the trade-off between the climate impact of CO emissions and contrails for a single flight, in terms of the absolute global warming potential and absolute global temperature potential metrics for time horizons of 20, 50 and 100 years. We use the framework to illustrate the maximum extra distance (with no altitude changes) that can be added to a flight and still reduce its overall climate impact. Small aircraft can fly up to four times further to avoid contrailing than large aircraft. The results have a strong dependence on the applied metric and time horizon. Applying a conservative estimate of the uncertainty in the contrail radiative forcing and climate efficacy leads to a factor of 20 difference in the maximum extra distance that could be flown to avoid a contrail. The impact of re-routing on other climatically-important aviation emissions could also be considered in this framework.