Neural-Network Vector Controller for Permanent-Magnet Synchronous Motor Drives: Simulated and Hardware-Validated Results

This paper focuses on current control in a permanentmagnet synchronous motor (PMSM). The paper has two main objectives: The first objective is to develop a neural-network (NN) vector controller to overcome the decoupling inaccuracy problem associated with conventional PI-based vector-control methods. The NN is developed using the full dynamic equation of a PMSM, and trained to implement optimal control based on approximate dynamic programming. The second objective is to evaluate the robust and adaptive performance of the NN controller against that of the conventional standard vector controller under motor parameter variation and dynamic control conditions by (a) simulating the behavior of a PMSM typically used in realistic electric vehicle applications and (b) building an experimental system for hardware validation as well as combined hardware and simulation evaluation. The results demonstrate that the NN controller outperforms conventional vector controllers in both simulation and hardware implementation

The Impact of Small Spinal Curves in Adolescents That Have Not Presented to Secondary Care:A Population-Based Cohort Study

Study Design: A prospective, population-based, birth cohort study. Objective: The aim of this study was to identify whether there is any hidden burden of disease associated with smaller spinal curves. Summary of Background Data: Adolescent idiopathic scoliosis is present in 3% to 5% of the general population. Large curves are associated with increased pain and reduced quality of life. However, no information is available on the impact of smaller curves, many of which do not reach secondary care. Methods: The Avon Longitudinal Study of Parents and Children (ALSPAC) recruited over 14,000 pregnant women from the Bristol area of South-West England between 1991 and 1992 and has followed up their offspring regularly. At age 15, presence or absence of spinal curvature ≥6 degrees in the offspring was identified using the validated dual-energy X-ray absorptiometry Scoliosis Measure on 5299 participants. At age 18, a structured pain questionnaire was administered to 4083 participants. Logistic regression was used to investigate any association between presence of a spinal curve at age 15 and self-reported outcomes at age 18 years. Results: Full data were available for 3184 participants. Two hundred two (6.3%) had a spinal curve ≥6 degrees and 125 (3.9%) had a curve ≥10 degrees (median curve size of 11 degrees). About 46.3% reported aches and pains that lasted for a day or longer in the previous month. About 16.3% reported back pain. Those with spinal curves were 42% more likely to report back pain than those without (odds ratio 1.42, 95% confidence interval 1.00–2.02, P = 0.047). Those with spinal curves had more days off school and were more likely to avoid activities that caused their pain. Conclusion Our results highlight that small scoliotic curves may be less benign than previously thought. Teenagers with small curves may not present to secondary care, but are nonetheless reporting increased pain, more days off school, and avoidance of activities. These data suggest that we should reconsider current scoliosis screening and treatment practices. Level of Evidence: 2 </p

Tracing Noble Gas Radionuclides in the Environment

Trace analysis of radionuclides is an essential and versatile tool in modern science and technology. Due to their ideal geophysical and geochemical properties, long-lived noble gas radionuclides, in particular, 39Ar (t1/2 = 269 yr), 81Kr (t1/2 = 2.3x10^5 yr) and 85Kr (t1/2 = 10.8 yr), have long been recognized to have a wide range of important applications in Earth sciences. In recent years, significant progress has been made in the development of practical analytical methods, and has led to applications of these isotopes in the hydrosphere (tracing the flow of groundwater and ocean water). In this article, we introduce the applications of these isotopes and review three leading analytical methods: Low-Level Counting (LLC), Accelerator Mass Spectrometry (AMS) and Atom Trap Trace Analysis (ATTA)

Experiences of living with chronic back pain: The physical disabilities

Purpose. Back-related functional limitations are largely assessed using lists of activities, each scored on a yes/no basis and the scores then summed. This provides little information about how chronic back pain (CBP) patients live with their condition. This study describes the consequences of living day-to-day with CBP and documents the 'insider' accounts of its impact on daily life. Method. Unstructured interviews, using the 'Framework' approach with topic guide, were recorded and transcribed verbatim. Subjects were sampled for age, sex, ethnicity and occupation from new referrals with back pain to a rheumatology outpatient clinic. Eleven subjects (5 male, 6 female) were interviewed either in English (n = 9) or their preferred language (n = 2). Interviews were read in-depth twice to identify the topics. Data were extracted in phrases and sentences using thematic content analysis. Results. Four themes emerged: sleep/rest, mobility, independence and leisure. All subjects reported issues about sleep and rest, nine about mobility, seven about independence and six on leisure. Most descriptions concerned loss and limitation in daily life. Strategies for coping with sleep disruption and physical limitations were described. Conclusions. Subjects provided graphic 'in-depth' descriptions of experiences living with CBP every day; expressed regret at the loss of capabilities and distress at the functional consequences of those losses. Facilitating 'adjustment' to 'loss' may be more helpful than inferring the potential for a life free of pain as a result of therapeutic endeavours

The Swedish Spine Register: development, design and utility

The Swedish Spine Register enables monitoring of surgical activities focusing on changes in trends over time, techniques utilized and outcome, when implemented in general clinical practice. Basic requirements for a prosperous register are unity within the profession, mainly patient-based documentation and a well functioning support system. This presentation focuses on the development and design of the register protocol, problems encountered and solutions found underway. Various examples on how the results can be presented and utilized are given as well as validation. Register data demonstrate significant gender differences in lumbar disc herniation surgery with females having more pain, lower quality of life and more pronounced disability preoperatively while improvement after surgery is similar between genders. Quality of life after surgery for degenerative disorders is significantly improved for disc herniation, stenosis, spondylolisthesis and disc degenerative disorders. Over the last 10 years, surgical treatment for spinal stenosis has increased gradually while disc herniation surgery decreases regarding yearly number of procedures. An added function to the register enables more complex prospective clinical studies to include register data together with data suitable for the individual study. A common core set of demographic, surgical and outcome parameters would enable comparisons of clinical studies within and between nations

Randomised controlled trial for evaluation of fitness programme for patients with chronic low back pain

Objective: To evaluate a progressive fitness programme for patients with chronic low back pain.Design: Single blind randomised controlled trial. Assessments were carried out before and after treatment by an observer blinded to the study and included a battery of validated measures. All patients were followed up by postal questionnaire six months after treatment.Setting: Physiotherapy department of orthopaedic hospital.Subjects: 81 patients with chronic low back pain referred from orthopaedic consultants for physiotherapy. The patients were randomly allocated to a fitness programme or control group.Intervention: Both groups were taught specific exercises to carry out at home and referred to a back-school for education in back care. Patients allocated to the fitness class attended eight exercise classes over four weeks in addition to the home programme and backschool.Results: Significant differences between the groups were shown in the changes before and after treatment in scores on the Oswestry low back pain disability index (

Dysplasia epiphysealis hemimelica of the talus

Dysplasia epiphysealis hemimelica is a rare developmental disorder with unknown etiology affecting epiphysis in childhood. The lesion is an osteochondroma arising from the epiphysis and increasing in size until skeletal maturity is reached. Surgical treatment is mandatory when symptoms such as pain, joint impingement or deformation are present, and yields good results when the mass is juxtaarticular or extraarticular. In those cases where articular symptoms are not present and only mass evolution is observed, surgical treatment is not recommended before skeletal maturity has been reached. A case of DEH located in the talus and successfully treated with surgery is presented

Observation of single collisionally cooled trapped ions in a buffer gas

Individual Ba ions are trapped in a gas-filled linear ion trap and observed with a high signal-to-noise ratio by resonance fluorescence. Single-ion storage times of ~5 min (~1 min) are achieved using He (Ar) as a buffer gas at pressures in the range 8e-5 - 4e-3 torr. Trap dynamics in buffer gases are experimentally studied in the simple case of single ions. In particular, the cooling effects of light gases such as He and Ar and the destabilizing properties of heavier gases such as Xe are studied. A simple model is offered to explain the observed phenomenology.Comment: 5 pages, 4 figures, accepted for publication in Phys. Rev. A. Minor text and figure change