Impacts of Climate Change on Snow Avalanche Activity Along a Transportation Corridor in the Tianshan Mountains

Snow avalanches can repeatedly occur along the same track under diferent snowpack and meteorological conditions during the snow season in areas of snow avalanche activity.The snowfall,air temperature,and snow cover can change dramatically in a warming climate,causing signifcant changes in the snow avalanche risk.But how the risk of snow avalanche activity during the snow season will change under a warming climate remains an open question.Based on the observed meteorological and snowpack data from 1968 to 2021 and the snow avalanche activity data during the 2011–2021 snow seasons along a transportation corridor in the central Tianshan Mountains that has a typical continental snow climate,we analyzed the temporal distribution of the snow avalanche activity and the impacts of climate change on it.The results indicate that the frequency of the snow avalanche activity is characterized by a Gaussian bimodal distribution,resulting from interactions between the snowfall,air temperature,and snowpack evolution.In addition,the active period of wet snow avalanches triggered by temperature surges and high solar radiation has gradually moved forward from the second half to the frst half of March with climate warming.The frequency and size of snowfall-triggered snow avalanches showed only a slight and insignifcant increase.These fndings are important for rationally arranging snow avalanche relief resources to improve the risk management of snow avalanche disasters,and highlight the necessity to immediately design risk mitigation strategies and disaster risk policies to improve our adaptation to climate change.

Stretchable on-skin touchless screen sensor enabled by ionic hydrogel

Screen sensors are the most commonly used human-machine interfaces in our everyday life,which have been extensively applied in personal electronics like cellphones.Touchless screen sensors are attracting growing interest due to their distinct advantages of high interaction freedom,comfortability,and hand hygiene.However,the material compositions of current touchless screen sensors are rigid and fragile,hardly meeting the needs of wearable and stretchable on-skin electronics development.Additionally,these touchless screen sensors are also restricted by high power consumption,limited gesture types of recognition,and the requirement of light conditions.Here,we report a stretchable on-skin touchless screen sensor(OTSS)enabled by an ionic hydrogel-based triboelectric nanogenerator(TENG).Compared with current touchless screen sensors,the OTSS is stretchable,self-powered,and competent to recognize diverse gestures by making use of charges naturally carried on fingers without the need of sufficient light conditions.An on-skin noncontact screen operating system is further demonstrated on the basis of the OTSS,which could unlock a cellphone interface in touchless operation mode on the human skin.This work for the first time introduces the on-skin touchless concept to screen sensors and offers a direction to develop new-generation screen sensors for future cellphones and personal electronics.

Experimental comparison between aircraft fuel tank inerting processes using NEA and MIG

Fuel tank inerting technologies are able to reduce the fire risk by injection of inert gas into the ullage or fuel, the former called ullage washing and the latter fuel scrubbing. The Green On-Board Inert Gas Generation System（GOBIGGS） is a novel technology based on flameless catalytic combustion, and owning to its simple structure and high inerting efficiency, it has received a lot of attentions. The inert gas in the GOBIGGS is mainly comprised of CO2, N2, and O2（hereinafter, Mixed Inert Gas（MIG））, while that in the On-Board Inert Gas Generation System（OBIGGS）, which is one of the most widely used fuel tank inerting technologies, is NitrogenEnriched Air（NEA）. The solubility of CO2 is nearly 20 times higher than that of N2 in jet fuels,so the inerting capability and performance are definitely disparate if the inert gas is selected as NEA or MIG. An inerting test bench was constructed to compare the inerting capabilities between NEA and MIG. Experimental results reveal that, if ullage washing is adopted, the variations of oxygen concentrations on the ullage and in the fuel are nearly identical no matter the inert gas is NEA or MIG. However, the ullage and dissolved oxygen concentrations of MIG scrubbing are always higher than those of NEA scrubbing.

Measurement of mass diffusion coefficients of O_2 in aviation fuel through digital holographic interferometry

The experimental apparatus to measure the mass diffusion coefficients of O2 in aviation fuel was constructed based on the digital holographic interferometry method. The theory of mass diffusion coefficient and interference image processing were introduced in detail. The accuracy of the experiment was verified by measuring the mass diffusion coefficient of 0.33 mol/L KCl in aqueous solution at 298.15 K. The mass diffusion coefficients of O_2 in RP3 and RP5 aviation fuels were measured at temperature from 278.15 K to 333.15 K, and the Arrhenius equation was employed to fit the experimental data. In terms of the Stokes-Einstein equation, the viscosities of these two aviation fuels were tested to estimate the correlation among mass diffusion coefficient, viscosity and temperature. A uniform polynomial calculation correlation was proposed to predict the mass diffusion coefficients of O_2 in both RP3 and RP5 aviation fuels, and its accuracy is considerably higher than that of the Stokes-Einstein equation.

3D printed triboelectric nanogenerator as self-powered human–machine interactive sensor for breathing-based language expression

Human–machine interfaces(HMIs)are important windows for a human to communicate with the outside world.The current HMI devices such as cellphones,tablets,and computers can be used to help people with aphasia for language expression.However,these conventional HMI devices are not friendly to some particular groups who also lose their abilities of physical movements like in the intensive care unit(ICU)or vegetative patients to realize language expression.Herein,we report a breath-driven triboelectric nanogenerator(TENG)acting as a HMI sensor for language expression through human breathing without voice controls or manual operations.The TENG is integrated within a mask and fabricated via a three-dimensional(3D)printing method.When wearing the mask,the TENG can produce responsive electric signals corresponding to the airflow from breathing,which is capable of recognizing human breathing types with different intensities,lengths,and frequencies.On the basis of the breathing recognition ability,a breathing-based language expressing system is further developed through introducing the Morse code as a communication protocol.Compared with conventional language expressing devices,this system can extract subjective information of a person from breathing behaviors and output corresponding language text,which is not relying on voices or physical movements.This research for the first time introduces the self-powered breathing-based language expressing method to the field of HMI technology by using a 3D printed TENG,and could make HMI interactions become more friendly and fascinating.

Oxygen concentration variation in ullage influenced by dissolved oxygen evolution

To determine the oxygen concentration variation in ullage that results from dissolved oxygen evolution in an inert aircraft fuel tank,the CFD method with a mass transfer source is applied in the present study.An experimental system is also designed to evaluate the accuracy of the CFD simulations.The dissolved oxygen evolution is simulated under different conditions of fuel load and initial oxygen concentration in ullage of an inert fuel tank with stimulations of heating and pressure decrease.The increase in the oxygen concentration in ullage ranges from 0.82%to 5.92%upon stimulation of heating and from 0.735%to 12.36%upon stimulation of a pressure decrease for an inert ullage in the simulations.The heating accelerates the release of the dissolved oxygen from the fuel by increasing the mass transfer rate in the mass transfer source and decreasing the pressure,thereby accelerating the dissolved oxygen evolution by increasing the concentration difference between the gas and the fuel.The time constant that represents the oxygen evolution rate is independent of the initial oxygen concentration in ullage of an inert tank but depends closely on the fuel load,temperature and pressure.The time constant can be fitted using a polynomial equation relating the fuel load to temperature in the heating stimulation with an accuracy of 4.77%.Upon stimulation of a pressure decrease,the time constant can be expressed in terms of the fuel load and the pressure,with an accuracy of 5.02%.

脑血管介入诊疗并发造影剂脑病二例报告

近年来,随着国内血管内介入治疗技术的普遍开展,术中造影剂的使用亦趋频繁,造影剂导致的不良反应也随之增加,这些不良反应主要包括过敏反应、造影剂肾损害、造影剂脑病(contrast-induced encephalopathy,CIE)、心血管反应等。其中CIE是较为罕见的造影剂使用后的神经系统并发症,其主要临床表现为非特异性神经精神症状、皮质盲、癫痫、局灶性神经功能障碍等[1]。CIE患者大多预后良好,但亦有部分患者遗留神经系统后遗症甚至死亡,尽早识别、诊断并给予针对性治疗是改善患者预后的关键[2]。

Effect of fuel type on the performance of an aircraft fuel tank oxygen-consuming inerting system

The properties of aviation fuel have a great influence on the performance of oxygenconsuming inerting systems. Based on the establishment of the catalytic inerting process, the flow relationship of each gas component flowing through the catalytic reactor was derived. The mathematical model of the gas concentration in the gas phase of the fuel tank was established based on the mass conservation equation, and the fuel tank model was verified by performing experiments.The results showed that the fuel type exerts a considerably higher influence on the performance of the oxygen-consuming inerting system compared to the corresponding influence on the hollow fiber membrane system, and the relative magnitude of the inerting rates of the four fuel types is RP5 > RP3 > RP6 > JP8. In addition, a higher catalytic efficiency or fuel load rate corresponds to a higher rate of decrease of the oxygen concentration in the gas phase, and the inerting time is inversely proportional to the suction flow rate of the fan. When different fuels are used, the amount of cooling gas and water released from the inerting system are different. Therefore, the influence of fuel type on the system performance should be extensively considered in the future.