Quantum-electrodynamic magnetic reconnection as the origin of the FRB 200428-associated X-ray burst from SGR J1935+2154

Magnetars, often under the name soft gamma-ray repeaters (SGRs) or anomalous X-ray pulsars, are highly magnetized neutron stars that exhibit diverse X-ray activities. Recently, a unique non-thermal X-ray burst with cut-off energy up to 84 keV is detected and thought to be associated with the fast radio burst (FRB) 200428 in the same single explosive event from SGR J1935+2154, as their spectra show similar feature of narrow double peaks that are emitted almost simultaneously. However, the physical origin of this FRB 200428-associated X-ray burst is still unknown yet. Here, with the first cross-scale numerical simulation in which modeling of particle acceleration by magnetic reconnections is self-consistently coupled with that of photon emission by multiple Compton scatterings, we identify that magnetic reconnection at the quantum-electrodynamic field strength inside the magnetar magnetosphere is the much likely driving source of such FRB-associated non-thermal X-ray burst. Both its temporal and spectral features are well reproduced in our simulations by assuming the plasma magnetization parameter σ~102-103 in consistency with the astronomical observations. The results could greatly promote our understandings of various X-ray burst events from magnetars.

Mechatronics design of self-adaptive under-actuated climbing robot for pole climbing and ground moving

Climbing robots have broad application prospects in aerospace equipment inspection, forest farm monitoring, and pipeline maintenance. Different types of climbing robots in existing research have different advantages. However, the self-adaptability and stability have not been achieved at the same time. In order to realize the self-adaptability of holding and climbing stability, this work proposes a new type of climbing robot under the premise of minimizing the driving source. The robot realizes stable multifinger holding and wheeled movement through two motors. At the same time, the robot has two different working modes, namely pole climbing and ground crawling. The holding adaptability and climbing stability are realized by underactuated holding mechanism and model reference adaptive controller (MRAC). On the basis of model design and parameter analysis, a prototype of the climbing robot is built. Experiments prove that the proposed climbing robot has the ability to stably climb poles of different shapes. The holding and climbing stability, self-adaptability, and climbing and crawling speed of the proposed climbing robot are verified by experiments.

Analysis of current characteristics of transformer bias caused by subway stray current based on measured data

The metro stray current, as the driving source which causes the magnetic bias of the urban network transformer, has the characteristics of rapid change, complex propagation path, and many influencing factors.It’s unknown where the stray current leaks from, and its specific value cannot be obtained through measurement methods.Therefore, this paper studies the characteristics of transformer neutral magnetic current bias based on the measured data and fault recording data in the process of measurement, and analyzes the influence of stray current on transformer in urban network.

Design and performance testing of areca nut thresher machine using solid triangle spike tooth type

Technology for handling agricultural products from areca nut has received less attention. However, the economic potential of the areca nut is comparable to that of other palm trees. Threshing areca nut from the bunch is one of the procedures that must be completed to obtain high-quality betel nut. Therefore, this research aims to design and test an areca nut threshing machine that uses a solid triangle spike-type threshing tooth. This study uses an experimental manufacturing method in the workshop and laboratory testing. A detailed engineering drawing of areca nut thresher machine is a guide in carrying out the manufacturer. The influence of rotational speed on the threshing shaft (34 rpm, 42 rpm, and 50 rpm) was investigated to determine the machinery’s performance (percentage of threshing results, engine capacity, and fuel consumption). This study indicates that the areca thresher machine has been successfully designed with a diesel motor driving source of 6.5 hp, 2200 rpm. Applied a rotational speed of 50 rpm will give the best percentage of threshing products. The increase in rotational speed applied to the threshing machine will be in line with the rise in the engine capacity. In addition, the fuel consumption of a diesel engine from this thresher machine is 0.039 l/hr.

Influence of the Abiotic Stress Conditions, Waterlogging and Drought, on the Bitter Sensometabolome as Well as Agronomical Traits of Six Genotypes of Daucus carota

Cultivated carrot is one of the most important vegetable plants in the world and favored by consumers for its typically sweet flavor. Unfortunately, the attractive sensory quality is hindered by a sporadic bitter off-taste. To evaluate the influence of the abiotic stress conditions, waterlogging and drought, on the bitter sensometabolome as well as agronomical traits of six genotypes of Daucus carota, a field trial was performed. Enabling the accurate tracing of carrots’ bitter compounds and therefore their metabolic changes, a fast and robust high-throughput UHPLC-MS/MS was developed and validated. Remarkably, the genotypes are the driving source for the biological fate of the bitter metabolites that are reflected in concentrations, dose-over-threshold factors, and fold changes. A certain influence of the irrigation level is observable but is overruled by its cultivar. Therefore, metabolic stress response in carrots seems to be genotype dependent. Hence, this study might help to plant specific carrot genotypes that are adapted to stress conditions evoked by future climatic changes.

The East–Freeman Automatic Vent: An interesting footnote in the history of mechanical ventilation

An example of the East–Freeman Automatic Vent from Oxford was found in the early anaesthesia equipment collection at St George Hospital, Sydney. It weighs less than 200 g and is representative of a group of miniature ventilators that were described in the 1960s, including the Minivent from South Africa and the Microvent from Canada. All relied on a pressure-operated inflating valve that was described in 1966 by Mitchell and Epstein from Oxford. The ventilators were compact, portable and were powered by the gas supply from the anaesthesia machine or other driving source that distended a reservoir bag. The main problem was that they could stick in the inspiratory phase. This led to pressure in the lungs rising towards the driving pressure. There was a risk of barotrauma to the patient if the system was not promptly disconnected. While theyhad provided an alternative to hand bagging, they were superseded, as more sophisticated and safer ventilators became widely available.