MWCNT Doped Reverse-Mode Polymer Network Liquid Crystals with Frequency Response Property

Polymer-liquid crystals(PLCs)are common materials for smart windows.However,PLC smart windows usually require high driving voltage to maintain transparency.We synthesized a novel PLC smart film by doping multi-wall carbon nanotubes(MWCNTs)into a reverse-mode polymer network liquid crystal(R-PNLC).

Impact of Quality and Government Subsidies on Elderly Care Services

In order to solve the problem of imbalance resource allocation and service income in the elderly care service industry,this article establishes three service income models in different situations for a single provider and a single integrator while considering the quality as well as government subsidies.The results showed that government subsidies can significantly improve quality efforts and service income with a mutual restriction between quality and service income.Government subsidies would have an impact on the quality,and they are more conducive to the service income of providers.When government subsidies are less than 80% of the service income,the incentive effect is better.

个性化采暖对热舒适的影响:综述

个性化空调因其同时具备节能潜力和满足个性化热舒适需求的能力而备受关注。作为个性化空调的重要组成,个性化采暖能在寒冷环境中维持人体热舒适,因而具备成为冬季重要采暖方式的潜力。为更好地促进个性化采暖的应用与发展,本文对现有研究成果进行了综述。将个性化采暖按其主要的热量传递方式划分为传导式、对流式、辐射式和组合式四类。总结了各方式的原理、具体形式及特点。比较了主要的三类(传导、对流和辐射)个性化采暖方式对热舒适影响的特点,并将其影响规律定量化。总结和归纳了基于环境参数和生理参数的人体局部热舒适评价模型,同时为用户在冬季选择合适的采暖设备提供了理论依据。

A new ventilation mode of air conditioning in subway vehicles and its air distribution performance

The traditional ventilation mode of subway vehicles adopts the form that the inlets and outlets are placed on the upper part of the cabin.The air distribution formed in this mode often cause serious problems of thermal comfort and energy consumption.In order to solve these problems caused by the traditional ventilation mode,a new hybrid ventilation mode was proposed.The hybrid ventilation mode uses both upper and underside air supply inlets.A method for evaluating the air distribution performance of subway air conditioning was developed.The method applies non-uniformity coefficients,maximum temperature difference,air diffusion performance index,modified energy utilization coefficient and Air short-circuit comprehensive coefficient.Air short-circuit comprehensive coefficient was a new index to evaluate the degree of air short-circuit of supply air.Based on the airflow simulation,the air distribution performance for the hybrid ventilation mode was evaluated using these indexes,and compared with the traditional ventilation mode.The results show that compared with the traditional ventilation mode,the hybrid ventilation mode has more uniform temperature distribution,better thermal comfort,higher energy utilization efficiency and lower degree of air short-circuit of supply air.

Numerical investigation to evaluate the effects of gravity and pressure on flame structure and soot formation of turbulent non-premixed methaneair flame

In this study,a turbulent non-premixed(diffusion)methane-air flame has been investigated computationally to analyze the influences of pressure and gravity on flame structure and sooting characteristics between 1 and 10 atm.The simulation has been conducted in a 2-D axisymmetric computational domain using the finite volume-based computational fluid dynamics(CFD)code.The interaction of turbulence and chemistry is modeled by considering the steady laminar flamelet model(SLFM)and the GRI Mech 3.0 chemical mechanism.The radiative heat transfer calculation is carried out by considering the discrete ordinate(DO)method and the weighted sum grey gas model(WSGGM).The semi-empirical Moss-Brookes model is considered to calculate soot.The impact of gravity on flame and sooting characteristics are evaluated by comparing the normal-gravity flames with the zero-gravity flames.The effect of soot and radiation on flame temperature is also examined.The results show a close agreement with the measurement when both soot and radiation are included in the numerical modeling.The rates of soot formation,surface growth,and oxidation increase with increased operating pressure,regardless of gravity.Zero-gravity flames have a higher soot volume fraction,a wider soot-containing zone,a higher CO mass fraction,and a lower flame temperature than normal-gravity flames while maintaining constant pressure.In normal-gravity flames,the CO mass fraction decreases with pressure,whereas it increases with pressure rise in flames of zero gravity.Flames of zero gravity appear taller and broader compared to the flames of normalgravity for a fixed pressure.An increase in pressure significantly reduces the flame length and width in normal-gravity flames.However,the pressure elevation has little effect on the shape of a zero-gravity flame.The outcomes of the present study will assist in fully understanding the combustion and sooting characteristics of turbulent diffusion flames that will help design and develop high-efficiency,pollutant-free combustion devices and fire suppression systems for space application.

Advanced liquid crystal-based switchable optical devices for light protection applications:principles and strategies

With the development of optical technologies,transparent materials that provide protection from light have received considerable attention from scholars.As important channels for external light,windows play a vital role in the regulation of light in buildings,vehicles,and aircrafts.There is a need for windows with switchable optical properties to prevent or attenuate damage or interference to the human eye and light-sensitive instruments by inappropriate optical radiation.In this context,liquid crystals(LCs),owing to their rich responsiveness and unique optical properties,have been considered among the best candidates for advanced light protection materials.In this review,we provide an overview of advances in research on LC-based methods for protection against light.First,we introduce the characteristics of different light sources and their protection requirements.Second,we introduce several classes of light modulation principles based on liquid crystal materials and demonstrate the feasibility of using them for light protection.In addition,we discuss current light protection strategies based on liquid crystal materials for different applications.Finally,we discuss the problems and shortcomings of current strategies.We propose several suggestions for the development of liquid crystal materials in the field of light protection.