Comparison and visualisation of high-resolution transport modelling with aircraft measurements

This article presents a case study of a comparison of an Eulerian chemical transport model (CTM) and Lagrangian chemical model with measurements taken by aircraft. High-resolution Eulerian integrations produce improved point-by-point comparisons between model results and measurements compared to low resolution. The Lagrangian model requires mixing to be introduced in order to model the measurements.

Predictive algorithm for the roll control autopilot of a jet fighter aircraft

Predictive controllers are often only applicable for open-loop stable systems. In this paper two such controllers are designed to operate on open-loop critically stable systems, each of which is used to find the control inputs for the roll control autopilot of a jet fighter aircraft. It is shown how it is quite possible for good predictive control to be achieved on open-loop critically stable systems.

Automatic X-ray screening of aircraft hold luggage

R. Benjamin (1995) addressed the application of the “object 3D” X ray reconstruction technique for electronically “unpacking” suspect items, when screening aircraft luggage. However, there is no satisfactory solution to the mass screening of hold luggage. Computed Tomography, CT, entails excessive radiation dosages, and its rate of throughput is quite inadequate. A novel variant of “object 3D” is therefore put forward, adapting some of the technology of existing cabin luggage screening systems-but on a substantially larger scale-which does achieve the required throughput at an acceptable radiation dosage and cost.

Word frequency and bigram frequency effects on linguistic processing and speech motor performance in individuals with aphasia and normal speakers

Models of normal word production are well specified about the effects of frequency of linguistic stimuli on lexical access, but are less clear regarding the same effects on later stages of word production, particularly word articulation. In aphasia, this lack of specificity of down-stream frequency effects is even more noticeable because there is relatively limited amount of data on the time course of frequency effects for this population. This study begins to fill this gap by comparing the effects of variation of word frequency (lexical, whole word) and bigram frequency (sub-lexical, within word) on word production abilities in ten normal speakers and eight mild–moderate individuals with aphasia. In an immediate repetition paradigm, participants repeated single monosyllabic words in which word frequency (high or low) was crossed with bigram frequency (high or low). Indices for mapping the time course for these effects included reaction time (RT) for linguistic processing and motor preparation, and word duration (WD) for speech motor performance (word articulation time). The results indicated that individuals with aphasia had significantly longer RT and WD compared to normal speakers. RT showed a significant main effect only for word frequency (i.e., high-frequency words had shorter RT). WD showed significant main effects of word and bigram frequency; however, contrary to our expectations, high-frequency items had longer WD. Further investigation of WD revealed that independent of the influence of word and bigram frequency, vowel type (tense or lax) had the expected effect on WD. Moreover, individuals with aphasia differed from control speakers in their ability to implement tense vowel duration, even though they could produce an appropriate distinction between tense and lax vowels. The results highlight the importance of using temporal measures to identify subtle deficits in linguistic and speech motor processing in aphasia, the crucial role of phonetic characteristics of stimuli set in studying speech production and the need for the language production models to account more explicitly for word articulation.

Speech motor control in fluent and dysfluent speech production of an individual with apraxia of speech and Broca’s aphasia

Apraxia of speech (AOS) is typically described as a motor-speech disorder with clinically well-defined symptoms, but without a clear understanding of the underlying problems in motor control. A number of studies have compared the speech of subjects with AOS to the fluent speech of controls, but only a few have included speech movement data and if so, this was primarily restricted to the study of single articulators. If AOS reflects a basic neuromotor dysfunction, this should somehow be evident in the production of both dysfluent and perceptually fluent speech. The current study compared motor control strategies for the production of perceptually fluent speech between a young woman with apraxia of speech (AOS) and Broca’s aphasia and a group of age-matched control speakers using concepts and tools from articulation-based theories. In addition, to examine the potential role of specific movement variables on gestural coordination, a second part of this study involved a comparison of fluent and dysfluent speech samples from the speaker with AOS. Movement data from the lips, jaw and tongue were acquired using the AG-100 EMMA system during the reiterated production of multisyllabic nonwords. The findings indicated that although in general kinematic parameters of fluent speech were similar in the subject with AOS and Broca’s aphasia to those of the age-matched controls, speech task-related differences were observed in upper lip movements and lip coordination. The comparison between fluent and dysfluent speech characteristics suggested that fluent speech was achieved through the use of specific motor control strategies, highlighting the potential association between the stability of coordinative patterns and movement range, as described in Coordination Dynamics theory.

Assessing the effectiveness of robot facilitated neurorehabilitation for relearning motor skills following a stroke

A growing awareness of the potential for machine-mediated neurorehabilitation has led to several novel concepts for delivering these therapies. To get from laboratory demonstrators and prototypes to the point where the concepts can be used by clinicians in practice still requires significant additional effort, not least in the requirement to assess and measure the impact of any proposed solution. To be widely accepted a study is required to use validated clinical measures but these tend to be subjective, costly to administer and may be insensitive to the effect of the treatment. Although this situation will not change, there is good reason to consider both clinical and mechanical assessments of recovery. This article outlines the problems in measuring the impact of an intervention and explores the concept of providing more mechanical assessment techniques and ultimately the possibility of combining the assessment process with aspects of the intervention.

The role of corticospinal tract damage in chronic motor recovery and neurorehabilitation: a pilot study

Background. With diffusion-tensor imaging (DTi) it is possible to estimate the structural characteristics of fiber bundles in vivo. This study used DTi to infer damage to the corticospinal tract (CST) and relates this parameter to (a) the level of residual motor ability at least 1 year poststroke and (b) the outcome of intensive motor rehabilitation with constraint-induced movement therapy (CIMT). Objective. To explore the role of CST damage in recovery and CIMT efficacy. Methods. Ten patients with low-functioning hemiparesis were scanned and tested at baseline, before and after CIMT. Lesion overlap with the CST was indexed as reduced anisotropy compared with a CST variability map derived from 26 controls. Residual motor ability was measured through the Wolf Motor Function Test (WMFT) and the Motor Activity Log (MAL) acquired at baseline. CIMT benefit was assessed through the pre—post treatment comparison of WMFT and MAL performance. Results. Lesion overlap with the CST correlated with residual motor ability at baseline, with greater deficits observed in patients with more extended CST damage. Infarct volume showed no systematic association with residual motor ability. CIMT led to significant improvements in motor function but outcome was not associated with the extent of CST damage or infarct volume. Conclusion. The study gives in vivo support for the proposition that structural CST damage, not infarct volume, is a major predictor for residual functional ability in the chronic state. The results provide initial evidence for positive effects of CIMT in patients with varying, including more severe, CST damage.

New advances in aircraft MRO services: data mining enhancement

Aircraft Maintenance, Repair and Overhaul (MRO) agencies rely largely on row-data based quotation systems to select the best suppliers for the customers (airlines). The data quantity and quality becomes a key issue to determining the success of an MRO job, since we need to ensure we achieve cost and quality benchmarks. This paper introduces a data mining approach to create an MRO quotation system that enhances the data quantity and data quality, and enables significantly more precise MRO job quotations. Regular Expression was utilized to analyse descriptive textual feedback (i.e. engineer’s reports) in order to extract more referable highly normalised data for job quotation. A text mining based key influencer analysis function enables the user to proactively select sub-parts, defects and possible solutions to make queries more accurate. Implementation results show that system data would improve cost quotation in 40% of MRO jobs, would reduce service cost without causing a drop in service quality.