Track-following in tape storage: Lateral tape motion and control

Achieving higher track densities in tape storage systems requires significant improvements in the track-following capabilities. The track-follow control system is used to reduce the misalignment between the tape and the recording head created by the lateral motion of the flexible medium. The characteristics of the lateral tape motion disturbance and their effect in the track-follow performance are identified. The effects from roller run-outs, reel eccentricities and tape paths with flangeless rollers are discussed. Control schemes are evaluated to improve the track-following capability and increase the track density on a magnetic tape.     

Absolute linearity measurements on a PbS detector in the infrared

The nonlinearity characteristics of a commercially available thin-film photoconductive PbS detector were experimentally investigated in the infrared using the National Physical Laboratory detector linearity characterization facility. The deviation from linearity of this detector was shown to be significant even for relatively low values of radiant power incident on the active area of the detector. For example, the linearity factor was approximately 0.8 when 0.6 microW of radiant power at a wavelength of 2.2 microm was illuminating a spot of 1 mm in diameter on the active area of the PbS detector. These figures demonstrate the poor linearity characteristics of this detector and provide a warning to other users of PbS detection systems. The deviation from linearity was shown to be a function of the size of the spot being illuminated on the detector active area, as well as the wavelength of the incident radiation. The deviation from linearity was shown to be a function of irradiance illuminating the detector for irradiance values lower than 1 microW mm(-2).     

EXPERIMENTAL INVESTIGATION AND MODELING OF THE INFLUENCE OF INDIRECT HEATING ON FLUIDIZED BED DRYING

Experimental results of fluidized bed drying with additional energy input by indirect heating are presented. A clear influence of moisture on wall-to-bed heat transfer coefficients is observed for particle diameters of 250 μm and 50 μm. Two different reasons for this influence may be distinguished in both, the measurements and theoretical considerations: 1 The change of bed and particle properties and 2 the increase of the local wall-to-particle heat transfer.     

Experimental study of combustion noise radiation during transient turbocharged diesel engine operation

Diesel engine noise radiation has drawn increased attention in recent years since it is associated with the passengers’ and pedestrians’ discomfort, a fact that has been acknowledged by the manufacturers and the legislation in many countries. In the current study, experimental tests were conducted on a truck, turbocharged diesel engine in order to investigate the mechanism of combustion noise emission under various transient schedules experienced during daily driving conditions, namely acceleration and load increase. To this aim, a fully instrumented test bed was set up in order to capture the development of key engine and turbocharger variables during the transient events. Analytical diagrams are provided to explain the behavior of combustion noise radiation in conjunction with cylinder pressure (spectrum), turbocharger and governor/fuel pump response. Turbocharger lag was found to be the main cause for the noise spikes during all test cases examined, with the engine injection timing calibration and the slow adjustment of cylinder wall temperature to the new fueling conditions playing a vital role. The analysis was extended with a quasi-steady approximation of transient combustion noise using steady-state maps, in order to better highlight the effect of dynamic engine operation on combustion noise emissions.     

Characterization of Lyophilization of Frozen Bulky Solids

Two methods to study the primary freeze-drying behavior of bulky solids are presented, namely, lyomicroscopy and neutron imaging. The applicability of both methods to visualize the evolution of the sublimation front is tested for maltodextrin particles with different sizes and solid concentrations. Exemplary results for both methods are reported and the applicability of both methods to study freeze-drying behavior of bulk solids is described. To estimate the impact of particle size and bed height for the freeze-drying of bulky solids, a modified Biot number is introduced to estimate the optimum particle size for a given bed height and formulation. The applicability of the two methods with regard to the modified Biot numbers is discussed.     

Enabling technologies for the ‘always best connected’ concept

‘Always Best Connected’ (ABC) is considered one of the main requirements for next generation networks. The ABC concept allows a person to have access to applications using the devices and network technologies that best suits his or her needs or profile at any time. Clearly, this requires the combination of a set of existing and new technologies, at all levels of the protocol stack, into one integrated system. In this paper, a considerable set of the technologies, that are expected to play a key role towards the ABC vision, are presented. Starting from a reference architecture, the paper describes the required enhancements at certain levels of a traditional protocol stack, as well as technologies for mobility and end‐to‐end Quality of Service (QoS) support. The paper concludes with a case study that reveals the advantages of the ABC concept. This article replaces a previously published version (Wireless Communications and Mobile Computing; 5 (2): 175‐191. [DOI: 10.1002/wcm.207]). Retraction notice DOI: 10.1002/wcm.426 . Copyright © 2006 John Wiley & Sons, Ltd.