What Makes an Effective Representation of Information: A Formal Account of Observational Advantages

In order to effectively communicate information, the choice of representation is important. Ideally, a chosen representation will aid readers in making desired inferences. In this paper, we develop the theory of observation: what it means for one statement to be observable from another. Using observability, we give a formal characterization of the observational advantages of one representation of information over another. By considering observational advantages, people will be able to make better informed choices of representations of information. To demonstrate the benefit of observation and observational advantages, we apply these concepts to set theory and Euler diagrams. In particular, we can show that Euler diagrams have significant observational advantages over set theory. This formally justifies Larkin and Simon’s claim that “a diagram is (sometimes) worth ten thousand words”.     

Ship wakes in radar imagery

In 1989 an experiment in Loch Linnhe, Scotland, was conducted to improve the understanding of radar images of internal-wave wakes generated by ships. During the experiment a multi-frequency synthetic-aperture radar (SAR) image containing several bright narrow V-shaped wakes was obtained during a period of low wind speed. One of the wakes imaged is caused by internal waves generated by a ship that was participating in the experiment. Three other wakes were also imaged which were generated by fishing vessels. The wakes of the fishing vessels are different in appearance to the internal-wave wake generated by the experiment ship. Given that the displacement of the fishing vessels is about four orders of magnitude less than the experiment ship it is unlikely that they could produce internal waves that could be detected by the radar. The fishing vessel wakes observed at two different radar frequencies can, however, be explained by the mechanism proposed by Munk et al. in 1987.     

The European Union’s contributions to international stability: the role of education and study mobilities

The efforts of the European Union for stabilisation and democratisation in Eastern Europe and the Balkan region covered a range of areas. While the impact of such measures and incentives testify for the progress on the path of regional reconciliation and democratisation, this record remains largely a top-down account, with governments and political leaders acting as principal agents of change and drivers of stability. The long-term efficiency of this type of approach cannot be guaranteed without genuine transformations at all society levels and layers. The role of the European Union’s educational exchange schemes, particularly Erasmus, may prove to be an instilling factor for regional reconciliation and a stability generator. The Erasmus scheme has been extremely successful and key to breaking cultural barriers and working across borders and disciplines. This study seeks to understand student experiences of two postgraduate programmes which deal with issues associated with international stability. The study used a case study research methodology and selected the case studies of the “MITRA” Erasmus Mundus Masters programme on Intercultural Mediation: Identities Mobilities and Conflict and the EM2-STEM (Entrepreneurship and Management Training in Science, Technology, Engineering and Mathematics) Erasmus Mundus programme. The study specifically investigates the experiences of students in these programmes and their experiences of intercultural interactions. From here an analysis is conducted to explore if European Union-funded study mobilities have shaped or transformed participating students’ views of international stability.     

The Ergonomics Society--the Society Lectures 1999: the Ergonomics Society: 50 years of growth

Developments in the Society are outlined since the early history was described by Edholm and Murrell. Major changes in the Society's operation and the context in which these changes took place are given. The changes in research directions, growth in educational facilities for professional education and the ever widening areas for the application of ergonomics are discussed. The consequences of these developments for the expansion of a recognition of the contribution of ergonomics, and the position of professionals in the international scene are touched upon.     

The effects of microwaves on airborne microorganisms.

This paper reports preliminary results of simple experiments carried out to study the effects of microwave irradiation at 2.45 GHz on fungi, yeast and bacteria of the type encountered in food processing plants or in enclosures containing individuals infected with tuberculosis mycobacterium (TB). The results are sufficiently encouraging to justify further multivariable experiments particularly with air circulation schemes in which the air can be sterilized in a circular cylindrical microwave cavity operating at a higher order mode.     

A novel instrument to quantify the tension of upper and lower eyelids.

An instrument was developed for the objective measurement of passive lid tension of the upper and lower eyelid. Eyelid tension is defined as the first derivative of the force over elongation function. Lid tension was determined by gripping the eyelid at the eyelashes and displacing the lid while measuring the force exerted by the eyelid. Two motorised spindles provided motion control of the gripper in anterior/posterior and nasal/temporal directions. Each axis was fitted with a sensitive force transducer to record the force while stretching and relaxing the eyelid. Motion control, data collection and data analysis were computer controlled, with various user-selectable options for measurement speed, direction and end-of-measurement conditions. Calibration of the instrument reduced the maximum error of the recorded forces to +/- 10 mN. Repeatability for on-eye measurements was verified by multiple measurements on the same eye under identical conditions. Preliminary results from a pilot study, investigating differences between Asian and Caucasian lid tension showed no statistically significant difference between the two groups.     

Linearity optimization of a high power Doherty amplifier based on post-distortion compensation

The linearity of a 30-W high-power Doherty amplifier is optimized using post-distortion compensation. A balanced high-power Doherty amplifier using two push-pull laterally-diffused metal-oxide semiconductor (LDMOS) field-effect transistors (FETs) is linearized by optimum adjustment of the peaking compensation line, shunt capacitors, and gate biases. The measured results of an optimized Doherty amplifier for a four-carrier wideband code division multiple access (W-CDMA) signal, achieved -43 dBc adjacent channel leakage ratio (ACLR) at a /spl plusmn/5 MHz offset frequency. This is an ACLR improvement of 12.2dB and 6.5dB in comparison to the Doherty amplifier before optimization and a ClassAB amplifier, respectively.     

Frequency Reuse Techniques with a Distributed Antenna System

The performance of cellular networks is strongly limited by inter-cell interference. In order to reduce this interference, several techniques have been proposed, e.g., the frequency reuse techniques and distributed antenna system (DAS). This paper investigates the combinations of hard frequency reuse (HFR) and soft frequency reuse (SFR) techniques with DAS in a unique cell architecture, which are called DAS–HFR and DAS–SFR, respectively. This paper analytically quantifies the performance of the downlink multi-cell for DAS–HFR and DAS–SFR in terms of the average spectral efficiency. This also shows, the most appropriate frequency reuse technique depends not only on the average achievable data rate inside the cell, but also on the guaranteed achievable data rate (the minimum achievable data rate which is necessary to be obtained regardless of geographic location). The results show that DAS–SFR improves the achievable data rate of cell edges in a multi-cell environment as compared to a DAS–HFR when frequency reuse factor 1 is utilized. The results also show that DAS–SFR significantly increases the system capacity as compared to the DAS–HFR when frequency reuse factor 3 is utilized.     

Low-Complexity Load Balancing with a Self-Organized Intelligent Distributed Antenna System

A high call blocking rate is a consequence of an inefficient utilization of system resources, which is often caused by a load imbalance in the network. Load imbalances are common in wireless networks with a large number of cellular users. This paper investigates a load-balancing scheme for mobile networks that optimizes cellular performance with constraints of physical resource limits and users quality of service demands. In order to efficiently utilize the system resources, an intelligent distributed antenna system (IDAS) fed by a multi base transceiver station (BTS) has the ability to distribute the system resources over a given geographic area. To enable load balancing among distributed antenna modules we dynamically allocate the remote antenna modules to the BTSs using an intelligent algorithm. A self-optimizing network for an IDAS is formulated as an integer based linear constrained optimization problem, which tries to balance the load among the BTSs. A discrete particle swarm optimization (DPSO) algorithm as an evolutionary algorithm is proposed to solve the optimization problem. The computational results of the DPSO algorithm demonstrate optimum performance for small-scale networks and near-optimum performance for large-scale networks. The DPSO algorithm is faster with marginally less complexity than an exhaustive search algorithm.