Rare Earths and Magnetic Refrigeration

Magnetic refrigeration is a revolutionary, efficient, environmentally friendly cooling technology, which is on the threshold of commercialization. The magnetic rare earth materials are utilized as the magnetic refrigerants in most cooling devices, and for many cooling application the Nd2Fe14B permanent magnets are employed as the source of the magnetic field. The status of the near room temperature magnetic cooling was reviewed.

Computational modelling and simulation to mitigate the risk of daylight exposure in tropical museum buildings

In museum design and operation,daylight is typically discouraged due to high risk of damaging the display objects.However,past studies in high-latitude regions have shown the possibility to apply daylight in museums,so long as it is carefully planned,and the display objects are not from the category of high responsive materials.In the tropical region,the influence of daylighting on light exposure on museum objects is still unknown.This study therefore aims to assess and mitigate the impact of annual daylight exposure on objects with low responsive materials in a tropical daylit museum building.Annual daylight modelling and simulation are performed to achieve the objective,followed with Morris sensitivity analysis and Mahalanobis distance classifier to optimise the outcome.It is found that either WWR or glazing transmissivity gives the greatest influence on the performance indicators.Based on the proposed optimisation algorithm,it is possible to determine the optimum solutions satisfying the performance indicators target,for a certain opening type.Overall,the contribution of this study is the proposed computational modelling and simulation methods to mitigate the exposure risk while optimising daylight as a renewable energy source.

Experiment and simulation to determine the optimum orientation of building-integrated photovoltaic on tropical building façades considering annual daylight performance and energy yield

Building-Integrated Photovoltaic(BIPV)on vertical façades is a potential PV application in today’s buildings.The performance of BIPV on façades is significantly influenced by the façade orientation.For tropical cities,the optimum façade orientation,in terms of maximum energy yield and daylight performance,cannot be simply determined,due to relatively symmetrical sun path throughout the day.This study therefore aims to determine the optimum orientation for BIPV on tropical building façades.To achieve the objective,experiment,modelling,and computational simulation are conducted to evaluate the BIPV energy yield and to predict the indoor daylight performance in a scale-model building with a 105Wp monocrystalline silicon PV,facing each cardinal orienta-tion in Bandung,Indonesia.The South orientation yields practically zero ASE_(1000,250),providing the best annual daylight performance,and yielding the most desirable value in four out of five daylight metrics.The greatest annual energy yield is at the North orientation,providing 179-186 kWh(95%prediction interval)per year,but with larger uncertainty compared to that at the South,due to direct sunlight occurrence.Based on three different objective functions,the South orientation is considered optimum for placing the BIPV panel on the prototype façade in the location.

Wafer-scale transfer route for top–down III-nitride nanowire LED arrays based on the femtosecond laser lift-off technique

The integration of gallium nitride(GaN)nanowire light-emitting diodes(nanoLEDs)on flexible substrates offers opportunities for applications beyond rigid solid-state lighting(e.g.,for wearable optoelectronics and bendable inorganic displays).Here,we report on a fast physical transfer route based on femtosecond laser lift-off(fs-LLO)to realize wafer-scale top–down GaN nanoLED arrays on unconventional platforms.Combined with photolithography and hybrid etching processes,we successfully transferred GaN blue nanoLEDs from a full two-inch sapphire substrate onto a flexible copper(Cu)foil with a high nanowire density(~107 wires/cm2),transfer yield(~99.5%),and reproducibility.Various nanoanalytical measurements were conducted to evaluate the performance and limitations of the fs-LLO technique as well as to gain insights into physical material properties such as strain relaxation and assess the maturity of the transfer process.This work could enable the easy recycling of native growth substrates and inspire the development of large-scale hybrid GaN nanowire optoelectronic devices by solely employing standard epitaxial LED wafers(i.e.,customized LED wafers with additional embedded sacrificial materials and a complicated growth process are not required).