433 research outputs found

    Documenting Torture and Ill-Treatment Amongst the Poor

    Get PDF
    This briefing highlights research that identifies potential deficiencies in the reporting of instances of torture and ill-treatment amongst the poorest members of society, and suggests actions that might be progressed to address these.ESRC-DFI

    Determining the Optimal Number of Pistons for Offshore Digital Winch Drives

    Get PDF
    In offshore winch drive applications, determining the required number of pistons in digital displacement motors is critical for minimizing torque ripples. Digital displacement motors have shown promise for improving energy efficiency for offshore operations, such as placing equipment on the seabed or mineral drilling. However, they are known for exhibiting significant torque ripples, which can affect load-handling precision. This paper estimates the required number of pistons for realizing a digital hydraulic winch drive based on information from a commercial winch. The proposed drive employs full-stroke displacement strategies at high speeds and partial-stroke at low speeds. By simulating steady-state operations, this study correlates torque output with position oscillations. The results show that 37 pistons are required to keep position oscillations below a benchmark threshold of 10 mm throughout the drive’s operating range to avoid hindering the drive’s performance. However, such a high piston count could result in high costs due to the large, expensive valves required for partial-stroke operations. Therefore, this paper suggests an alternative drive topology for future research, which could potentially reduce the number of pistons that are operated with partial strokes

    Estimating a population cumulative incidence under calendar time trends

    Get PDF
    Abstract Background The risk of a disease or psychiatric disorder is frequently measured by the age-specific cumulative incidence. Cumulative incidence estimates are often derived in cohort studies with individuals recruited over calendar time and with the end of follow-up governed by a specific date. It is common practice to apply the Kaplan\u2013Meier or Aalen\u2013Johansen estimator to the total sample and report either the estimated cumulative incidence curve or just a single point on the curve as a description of the disease risk. Methods We argue that, whenever the disease or disorder of interest is influenced by calendar time trends, the total sample Kaplan\u2013Meier and Aalen\u2013Johansen estimators do not provide useful estimates of the general risk in the target population. We present some alternatives to this type of analysis. Results We show how a proportional hazards model may be used to extrapolate disease risk estimates if proportionality is a reasonable assumption. If not reasonable, we instead advocate that a more useful description of the disease risk lies in the age-specific cumulative incidence curves across strata given by time of entry or perhaps just the end of follow-up estimates across all strata. Finally, we argue that a weighted average of these end of follow-up estimates may be a useful summary measure of the disease risk within the study period. Conclusions Time trends in a disease risk will render total sample estimators less useful in observational studies with staggered entry and administrative censoring. An analysis based on proportional hazards or a stratified analysis may be better alternatives

    PARALIGN: rapid and sensitive sequence similarity searches powered by parallel computing technology

    Get PDF
    PARALIGN is a rapid and sensitive similarity search tool for the identification of distantly related sequences in both nucleotide and amino acid sequence databases. Two algorithms are implemented, accelerated Smith–Waterman and ParAlign. The ParAlign algorithm is similar to Smith–Waterman in sensitivity, while as quick as BLAST for protein searches. A form of parallel computing technology known as multimedia technology that is available in modern processors, but rarely used by other bioinformatics software, has been exploited to achieve the high speed. The software is also designed to run efficiently on computer clusters using the message-passing interface standard. A public search service powered by a large computer cluster has been set-up and is freely available at , where the major public databases can be searched. The software can also be downloaded free of charge for academic use

    Improving Energy Efficiency and Response Time of an Offshore Winch Drive with Digital Displacement Motors

    Get PDF
    Offshore winch drives require high energy efficiency and control precision, making digital displacement motors an attractive solution due to their high efficiency and potential controllability. However, the response time and the realized energy efficiency of these motors are heavily dependent on the chosen displacement control strategy, especially at low-speed operation. This paper considers various displacement control strategies to investigate whether digital displacement motors are a viable solution for offshore winch drive applications. The motor specifications are derived based on the requirements of a commercial offshore winch drive system. The analysis reveals that various displacement control strategies should be used across the drive's operational speed range to ensure both satisfactory performance and high efficiency. Full-stroke and partial-stroke strategies are optimal for speeds above 28 rpm and 20 rpm, respectively, but unsuited for lower-speed operation. For speeds below 20 rpm, an improved sequential-stroke strategy is therefore presented. The proposed displacement control strategy provides instantaneous motor response and maintains high energy efficiency, although its robustness is slightly reduced at higher operating speeds above 20 rpm
    corecore