Learning to Communicate with Deep Multi-Agent Reinforcement Learning

We consider the problem of multiple agents sensing and acting in environments with the goal of maximising their shared utility. In these environments, agents must learn communication protocols in order to share information that is needed to solve the tasks. By embracing deep neural networks, we are able to demonstrate end-to-end learning of protocols in complex environments inspired by communication riddles and multi-agent computer vision problems with partial observability. We propose two approaches for learning in these domains: Reinforced Inter-Agent Learning (RIAL) and Differentiable Inter-Agent Learning (DIAL). The former uses deep Q-learning, while the latter exploits the fact that, during learning, agents can backpropagate error derivatives through (noisy) communication channels. Hence, this approach uses centralised learning but decentralised execution. Our experiments introduce new environments for studying the learning of communication protocols and present a set of engineering innovations that are essential for success in these domains

Bronchiectases at early chest computed tomography in children with cystic fibrosis are associated with increased risk of subsequent pulmonary exacerbations and chronic pseudomonas infection

AbstractBackgroundChildren with cystic fibrosis (CF) are often Pseudomonas aeruginosa (PsA) free and exhibit normal spirometry between the ages of 5 and 7. It is reported that computed tomography (CT) is more sensitive than FEV1 as an instrument in the identification of pulmonary disease. It is not known whether CF-CT scores in childhood may be used to highlight children at risk of developing severe disease.Aims1 — To assess the number of respiratory exacerbations (RTEs) during a follow-up period of 6years and their correlation with the CF-CT scores in young CF children. 2 — To assess whether PsA-negative CF children with high chest CF-CT scores are more likely to develop chronic PsA lung infection.Methods68 chest CT performed in patients without chronic PsA infection were scored. All patients (median age 7.8years) had at least 4 clinical, functional and microbiologic assessments/year in the subsequent 6years. RTE was defined as hospitalization and IV antibiotic treatment for respiratory symptoms.Results86.8% patients had <3 RTEs in the 6year follow-up period. The number of RTEs in the 6years subsequent to the CT scan was correlated to the bronchiectasis CT score (BCTS) (r=0.612; p<0.001) and to FEV1 at baseline (r=−0.495, p<0.001). A BCTS ≥17.5 identified patients with >3 RTEs during follow-up (sensitivity: 100%, specificity: 85%), while FEV1 did not. Only BCTS was significant in a logistic multivariate model (RR 1.15). BCTS was significantly lower and FEV1 higher in patients who did not develop chronic PsA infection by the end of the study.ConclusionIn CF children free from chronic PsA, both CT scores and FEV1 values demonstrate significant correlation with disease severity in the subsequent 6years but CT score has higher predictive value in the identification of patients at risk

Correction to "New Measurements of the Apparent Thermal Conductivity of Nanofluids and Investigation of Their Heat Transfer Capabilities"

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Thermal conductivity measurement of liquids in a microfluidic device

A new microfluidic-based approach to measuring liquid thermal conductivity is developed to address the requirement in many practical applications for measurements using small (microlitre) sample size and integration into a compact device. The approach also gives the possibility of high-throughput testing. A resistance heater and temperature sensor are incorporated into a glass microfluidic chip to allow transmission and detection of a planar thermal wave crossing a thin layer of the sample. The device is designed so that heat transfer is locally one-dimensional during a short initial time period. This allows the detected temperature transient to be separated into two distinct components: a short-time, purely one-dimensional part from which sample thermal conductivity can be determined and a remaining long-time part containing the effects of three-dimensionality and of the finite size of surrounding thermal reservoirs. Identification of the one-dimensional component yields a steady temperature difference from which sample thermal conductivity can be determined. Calibration is required to give correct representation of changing heater resistance, system layer thicknesses and solid material thermal conductivities with temperature. In this preliminary study, methanol/water mixtures are measured at atmospheric pressure over the temperature range 30–50°C. The results show that the device has produced a measurement accuracy of within 2.5% over the range of thermal conductivity and temperature of the tests. A relation between measurement uncertainty and the geometric and thermal properties of the system is derived and this is used to identify ways that error could be further reduced

Numerical model for the combustion of a thermal lance

A mathematical model for the operation of a thermal lance is developed and validated, with the focus on its heat transfer and kinetics behavior. It has been found that there is a "window"of combustion rates in which the thermal lance can operate, which is mainly dictated by the oxygen partial pressure. The particular value of the combustion rate can be set by adjusting the flow rate of the oxygen supply, which is practically done by manipulating the oxygen supply pressure. An open issue is the lack of experimental kinetics data for thermal lance combustion