125,319 research outputs found
Technological advances relevant to transport – understanding what drives them
Transport policy makers are increasingly perplexed by the pace of change in their sector and by the increasing influence of external actors. This leads to a variety of responses, including “business as usual”, technological optimism, technological fatalism and technological ignorance. To explore this perplexity and its justification, we examine four areas of technological advance relevant to transport: mobility as a service; unmanned aerial vehicles (drones); automated vehicles; and telehealth. In each case, we identify the principal underlying shifts which are driving these technological advances, concluding that there is considerable overlap: three of the advances rely on ubiquitous sensing and on artificial intelligence and all four rely, to some degree, on connectedness. We then explore these three “drivers”, finding that progress is steadier than may be generally thought. We discuss the implications for our set of transport-related technological developments, concluding that policy makers could approach the future with greater confidence than is currently typical. They could also draw on the concepts of anticipatory governance to support their management of emerging technology and, at the same time, of the influence of external actors
Solar radius measurements
Preliminary results of measurements made during 1979-1980 are discussed. Variability in the radius measurements of 0.4 pi is found, of unknown origin
Use of cohesive elements in fatigue analysis
Cohesive laws describe the resistance to incipient separation
of material surfaces. A cohesive finite element
is formulated on the basis of a particular cohesive
law. Cohesive elements are placed at the boundary
between adjacent standard volume finite elements
to model fatigue damage that leads to fracture at the
separation of the element boundaries per the cohesive
law. In this work, a cohesive model for fatigue
crack initiation is taken to be the irreversible loadingunloading
hysteresis that represents fatigue damage
occuring due to cyclic loads leading to the initiation of
small cracks. Various cohesive laws are reviewed and
one is selected that incorporates a hysteretic cyclic
loading that accounts for energetic dissipative mechanisms.
A mathematical representation is developed
based on an exponential effective load-separation cohesive
relationship. A three-dimensional cohesive element
is defined using this compliance relationship integrated
at four points on the mid-surface of the area
element. Implementation into finite element software
is discussed and particular attention is applied to numerical
convergence issues as the inflection point between
loading and 'unloading in the cohesive law is
encountered. A simple example of a displacementcontrolled
fatigue test is presented in a finite element
simulation. Comments are made on applications of
the method to prediction of fatigue life for engineering
structures such as pressure vessels and piping
Beyond FEV1 in COPD: a review of patient-reported outcomes and their measurement
Abstract: Patients with chronic obstructive pulmonary disease (COPD) present with a variety of symptoms and pathological consequences. Although primarily viewed as a respiratory disease, COPD has both pulmonary and extrapulmonary effects, which have an impact on many aspects of physical, emotional, and mental well-being. Traditional assessment of COPD relies heavily on measuring lung function, specifically forced expiratory volume in 1 second (FEV1). However, the evidence suggests that FEV1 is a relatively poor correlate of symptoms such as breathlessness and the impact of COPD on daily life. Furthermore, many consequences of the disease, including anxiety and depression and the ability to perform daily activities, can only be described and reported reliably by the patient. Thus, in order to provide a comprehensive view of the effects of interventions in clinical trials, it is essential that spirometry is accompanied by assessments using patient-reported outcome (PRO) instruments. We provide an overview of patient-reported outcome concepts in COPD, such as breathlessness, physical functioning, and health status, and evaluate the tools used for measuring these concepts. Particular attention is given to the newly developed instruments emerging in response to recent regulatory guidelines for the development and use of PROs in clinical trials. We conclude that although data from the development and validation of these new PRO instruments are emerging, to build the body of evidence that supports the use of a new instrument takes many years. Furthermore, new instruments do not necessarily have better discriminative or evaluative properties than older instruments. The development of new PRO tools, however, is crucial, not only to ensure that key COPD concepts are being reliably measured but also that the relevant treatment effects are being captured in clinical trials. In turn, this will help us to understand better the patient's experience of the disease
Deep Learning of Geometric Constellation Shaping including Fiber Nonlinearities
A new geometric shaping method is proposed, leveraging unsupervised machine
learning to optimize the constellation design. The learned constellation
mitigates nonlinear effects with gains up to 0.13 bit/4D when trained with a
simplified fiber channel model.Comment: 3 pages, 6 figures, submitted to ECOC 201
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