Natural gas vehicles: An option for Europe

In Europe natural gas vehicles play a minor role. A decisive reason for this is the dependence of most European countries from gas imports. Except for Italy, there is no tradition to use natural gas as fuel. In addition, there is a lack of infrastructure (e.g. fuelling stations). In contrast to Europe, in Latin American and Asian countries natural gas vehicles are widespread. Some countries foster natural gas vehicles because they have own gas resources. Many countries must reduce the high air pollution in big cities. Environmental reasons are the main motive for the use of natural gas vehicles in Europe. In last years, high oil prices stimulated the use of natural gas as fuel. European governments have developed incentives (e.g. tax reductions) to foster natural gas vehicles. However, the focus is on hybrid technology and the electric car, which, however, need further technical improvement. In contrast, the use of natural gas in conventional engines is technically mature. Additional gas imports can be avoided by further improvements of energy efficiency and the use of renewable energy. In sum, the market penetration of natural gas as fuel should be promoted in Europe.     

High efficiency,high switching speed,AlGaAs/GaAs P-HEMT DC–DC converter for integrated power amplifier modules

This paper presents a high efficiency, high switching frequency DC–DC buck converter in AlGaAs/GaAs technology, targeting integrated power amplifier modules for wireless communications. The switch mode, inductor load DC–DC converter adopts an interleaved structure with negatively coupled inductors. Analysis of the effect of negative coupling on the steady state and transient response of the converter is given. The coupling factor is selected to achieve a maximum power efficiency under a given duty cycle with a minimum penalty on the current ripple performance. The DC–DC converter is implemented in 0.5 μm GaAs p-HEMT process and occupies 2 × 2.1 mm² without the output network. An 8.7 nH filter inductor is implemented in 65 μm thick top copper metal layer, and flip chip bonded to the DC–DC converter board. The integrated inductor achieves a quality factor of 26 at 150 MHz. The proposed converter converts 4.5 V input to 3.3 V output for 1 A load current under 150 MHz switching frequency with a measured power efficiency of 84%, which is one of the highest efficiencies reported to date for similar current/voltage ratings.     

Frequency synthesiser architecture eliminating high speed frequency dividers for millimetre-wave applications

A frequency synthesiser architecture for millimetre-wave applications is proposed. The architecture is based on a triple-push oscillator, which functions both as a divider and oscillator. Thus, the proposed architecture eliminates the need for injection locked frequency dividers that are the main contributors to the limited tuning capability of millimetre- wave phase-locked loops. Since the proposed architecture is solely based on the performance of the triple-push oscillator, the measurement result of the first silicon triple-push oscillator at 30 GHz is presented to support the validity of the concept.     

Visibility requirements for the driver's stand of lift trucks. Experimental study of drivers' lateral head movements

Every year, lift trucks are involved in 9000 occupational accidents with stoppage of work. Most of those accidents are due to insufficient visibility from the driver's stand of lift trucks. Draft standards related to this characteristics take into account sideways head movements of from 300 to 600 mm, depending on the proposal. Continuous recording of movements was carried out on eight subjects in a test situation involving loading, unloading and driving the vehicle loaded and unloaded. On average, during 92% of the time driving the vehicle unloaded and 87% of time driving the vehicle loaded, the head is displaced less than 150 mm. Extreme positions are the least utilised: there is a gaussian distribution of movements around the central position. Movements accepted in draft standards are therefore overestimated. These experiments offer a partial interpretation of the differences of mobility observed between each of the four tasks.     

Sustainability performance evaluation in industry by composite sustainability index

The growing importance of sustainable development as a policy objective has initiated a debate about those suitable frameworks and tools useful for policy makers when making a sustainable decision. Composite indicators (CIs) aggregate multidimensional issues into one index, thus providing comprehensive information. However, it is frequently argued that CIs are too subjective, as their results undesirably depend on the normalization method, a specific weighting scheme, and the aggregation method of sub-indicators. This article applies different combinations of normalization, weighting, and aggregation methods for the assessment of an industrial case study, with the aim of determining the best scheme for constructing CIs. The applied methodology gradually aggregates sustainable development indicators into sustainability sub-indices and, finally, to a composite sustainability index. The normalization methods included in this analysis are: minimum–maximum, distance to a reference, and the percentages of annual differences over consecutive years. Equal weightings, the ‘benefit of the doubt’ approach, and budget allocation process were used for determining the weights of individual indicators and sustainability sub-indices. The linear, geometric, and non-compensatory multi-criteria approaches (NCMCs) were used as aggregation methods. The NCMC is modified to fit the two-level aggregation, then to sub-indices, and finally to a composite sustainable index. Also, a penalty criterion is introduced into the evaluation process with the aim of motivating the company to move towards sustainable development. The results are analyzed by variance-based sensitivity analysis. According to the results the recommended scheme for CIs’ construction is: distance to a reference–benefit of the doubt–linear aggregation.