INTUITIVE DECISION THEORY ANALYSIS AND THE EVALUATION MODEL

Intuitive decision-making studies the decision-maker’s decision-making behavior from the perspective of image thinking, which it poses a challenge to the classic decision-making hypothesis pursuing “optimal decision” because the outcomes of intuitive decision-making are difficulty to measure and its process isn’t easy to describe and control. Therefore it has not drawn the experts’ attention. This paper tries to establish an evaluation model of the intuitive decision-making as to giving a direction and inspiration of the quantization of intuitive decision-making, based on the systematic analysis of the existing domestic and international theory of intuitive decision-making. Key words: Intuitive decision-making, Thinking in images, The evaluation mode

Segatron: Segment-Aware Transformer for Language Modeling and Understanding

Transformers are powerful for sequence modeling. Nearly all state-of-the-art language models and pre-trained language models are based on the Transformer architecture. However, it distinguishes sequential tokens only with the token position index. We hypothesize that better contextual representations can be generated from the Transformer with richer positional information. To verify this, we propose a segment-aware Transformer (Segatron), by replacing the original token position encoding with a combined position encoding of paragraph, sentence, and token. We first introduce the segment-aware mechanism to Transformer-XL, which is a popular Transformer-based language model with memory extension and relative position encoding. We find that our method can further improve the Transformer-XL base model and large model, achieving 17.1 perplexity on the WikiText-103 dataset. We further investigate the pre-training masked language modeling task with Segatron. Experimental results show that BERT pre-trained with Segatron (SegaBERT) can outperform BERT with vanilla Transformer on various NLP tasks, and outperforms RoBERTa on zero-shot sentence representation learning.Comment: Accepted by AAAI 202

Quiet power-free cooling system enabled by loop heat pipe

Taking full advantage of LHP’s efficient long distance heat transport capability, a LHP-based power-free cooling system has been developed in this work. The heat source was simulated by a film heater, which was connected to the cylindrical evaporator of the LHP via an aluminum saddle. The condenser line was embedded into the bottom surface of a fin radiator where heat dissipation to the ambient was completely by air natural convection. Extensive experiments on this cooling system were conducted, mainly focusing on its startup and system thermal resistance. Experimental results show that this cooling system can successfully start up with a very small heat load. With the film heater temperature not exceeding 80 °C, this cooling system can manage a heat load as large as 150 W over a distance of 1.05 m, corresponding to a system thermal resistance about 0.30 °C/W. Moreover, this cooling system exhibited very strong anti-gravity capability. With an adverse elevation of 0.5 m, it can still maintain normal operation, and no obvious performance decay was observed except an increased operating temperature at small heat loads. This work provides good design guidance and reference for future applications of this advanced cooling system

Nanoparticle-based solar vapor generation: An experimental and numerical study

Steam generation by nanofluid under solar radiation has attracted intensive attention recently. Due to strong absorption of solar energy, nanoparticle-based solar vapor generation could have wide applications in many areas including desalination, sterilization and power generation. Steam generation of different concentrations of gold nanoparticle dispersions under focused sunlight of 5 sun and 10 sun were performed in this work. A numerical model combining radiative heat transfer, moisture transport, and laminar flow was established to investigate the temperature profile, evaporation rate above the surface and radiative intensity distribution inside the nanofluid. It was found that localized energy trapping at the surface of nanofluid was responsible for the fast vapor generation. To convert more solar radiative energy into latent heat of water (i.e., to vaporize water) at the surface, a new method was proposed to optimize the range of nanofluid concentration and optical depth for future solar vapor generator design

Nanoparticles enabled pump-free direct absorption solar collectors

Developing renewable energy technologies, especially solar energy-based, is of great importance to secure our energy future. Current solar thermal systems, however, have relatively low utilization efficiencies, limited not only by their low solar energy capture efficiency but also the auxiliary pumping power to circulate the working fluid. Here an innovative nanoparticle enabled pump-free direct absorption solar collector concept is presented, which combines the advantages of volumetric solar harvesting and oscillating heat pipes. Two different flow modes have been observed when the concentration of nanofluid is different. There is an optimum filling ratio when the thermal resistance reaches the minimum. Validation experiments show that the proposed concept can efficiently harvest solar energy and spontaneously transfer the heat into targeted areas, providing a novel approach for efficient solar energy utilization

Evaporation/boiling heat transfer characteristics in an artery porous structure

Nucleate boiling is one of the most efficient and effective heat transfer modes, but is limited by the critical heat flux (CHF). An innovative artery porous structure was proposed in this work to enhance the CHF based on the concept of "phase separation and modulation" by forming individual flow paths for liquid supply and vapor venting while keeping the liquid/vapor interface located in the porous structure. In the experiment, the porous structure was made of sintered copper microparticles, multiple arteries were machined directly on the heated surface, and water was employed as the working fluid. The experimental results were compared with those on a flat surface, and a unique evaporation/boiling curve for the artery porous structure was revealed. The experiment validated the principle proposed here for CHF enhancement, and a maximum heat flux of 416 W/cm2 on a heating area of 0.78 cm2 was achieved without the occurrence of any dryout. Further increase of heat flux was limited only by the design temperature of the electrical heater, and a much higher CHF can be expected. In addition, the effects of pore size, artery depth and contact condition on the evaporation/boiling heat transfer performance in the artery porous structure were also experimentally investigated, which can guide further design optimizations of this novel structure

Solar photothermal conversion characteristics of hybrid nanofluids: An experimental and numerical study

In this work, the Fe3O4, Cu and Au with different concentrations and the hybrid nanofluids were prepared and characterized to enhance the solar photothermal conversion performance based on the direct absorption concept. An extensive experimental study was carried out with different sample nanofluids under a solar simulator. The experiment was first conducted with Au nanofluid in three cases to investigate the effect of different test conditions, and the test condition where the simulated sunlight was absorbed by the sample nanofluid only once with minimum heat loss to the surroundings was determined for later research. Based on the experimental results, below conclusions have been reached: 1) the solar energy absorption performance of nanofluids with plasmonic nanomaterials, i.e., Au or Cu, is much better than that of nanofluids with non-plasmonic nanomaterials, i.e., Fe3O4 and DI water, due to the effect of localized surface plasmon resonance; 2) the larger the concentration, the higher the solar energy absorption efficiency, but the increasing rate of the absorption efficiency slows down gradually with the increase of the concentration; 3) a numerical method to predict photothermal conversion efficiency of nanofluid under solar radiation has been proposed; 4) the novel idea of employing hybrid nanofluid to enhance the solar absorption performance has been experimentally and numerical validated, which can enhance the solar photothermal conversion when mixing two nanofluids with different absorption peaks, and there is an optimal mixing volume fraction for hybrid nanofluid