Heat transfer performance of lithium bromide solution in falling film generator

An experimental investigation of vertical in-tube falling film heat transfer with different heat fluxes and concentrations of lithium bromide solution were conducted. The experiments show that the heat transfer coefficient increases with the decrease of inlet concentration and significantly increase with heat flux increase. An experimental correlation of falling film heat transfer coefficient is obtained.The comparison of falling film generator with immersed tube generator shows that the heat transfer coefficient is 4.37 times higher than that of immersed tube generator, which can significantly reduce the volume of the falling film generator. The volume of falling film generator is only 52.1% of the volume of immersed tube generator

An Improved DSA-Based Approach for Multi-AUV Cooperative Search

Multi-AUV cooperative target search problem in unknown 3D underwater environment is not only a research hot spot but also a challenging task. To complete this task, each autonomous underwater vehicle (AUV) needs to move quickly without collision and cooperate with other AUVs to find the target. In this paper, an improved dolphin swarm algorithm- (DSA-) based approach is proposed, and the search problem is divided into three stages, namely, random cruise, dynamic alliance, and team search. In the proposed approach, the Levy flight method is used to provide a random walk for AUV to detect the target information in the random cruise stage. Then the self-organizing map (SOM) neural network is used to build dynamic alliances in real time. Finally, an improved DSA algorithm is presented to realize the team search. Furthermore, some simulations are conducted, and the results show that the proposed approach is capable of guiding multi-AUVs to achieve the target search task in unknown 3D underwater environment efficiently

Gain Enhancement of a Dual-Band Antenna with the FSS

A dual-band directional antenna for Industrial, Scientific, and Medical (ISM) band application is proposed in this article. The antenna consists of two layers of substrates. The first layer contains the square loop loading with a meander stub to realize the dual band. The second layer is a frequency selective surface (FSS) structure, which is a periodic array with square loops. The phase shift from the FSS reflection and the distance between two layers are optimized to realize the field superposition, which could achieve gain enhancement and bandwidth improvement at two operating bands, simultaneously. The measured results indicate that within a 2.3–2.62 GHz range and a 4.9–6.45 GHz range, the |S11| of the antenna is less than −10 dB. The −10 dB impedance bandwidth is 13% and 27%, respectively. The gain of the antenna is 6.8 dB at 2.45 GHz and 9.0 dB at 5.8 GHz. Meanwhile, the antenna gain is over 8.5 dB from 5.0 GHz to 6.0 GHz. The working band of the antenna covers all bands of WLAN. The design has a good application prospect in the future

How Strategic Interaction of Innovation Policies between China’s Regional Governments Affects Wind Energy Innovation

Prior research has shown the importance of innovation policies that promote innovation in renewable energy, such as wind power. We study the impact of the strategic interaction of innovation policies between regional governments in terms of wind energy innovation in China. Based on panel data from 2007 to 2018 on a provincial level in China, we construct an innovation strength index of each province in the wind power industry and investigate the inductive effect of the technology-push policy and the demand-pull policy, as well as their spatial spillover effect on wind energy innovation. The results show that the technology-push policy of local governments has an obvious inductive effect on wind energy innovation in the region, while also having a negative spillover effect through R&D factor competitions between regions with geography proximity or with proximity in the ranking of R&D funds input. In terms of the demand-pull policy, only changes at the national level can produce positive spillover effects by promoting expectations of market growth. Yet, competition between regions with proximity in the ranking of wind energy resource reserves produce negative spillover effects. The findings should have a far-reaching impact on the sustainable development of global wind power

Cultivation in an Alpine Region: Implications for Soil Bacteria

Land use change is a major predictor for variations in soil bacteria, which plays a key role in maintaining soil multifunctionality and function of terrestrial ecosystems. The effects of land use change on the soil bacterial community in an alpine region at the Qinghai-Tibetan Plateau (QTP) were still unclear. In this study, we investigated soil bacterial profiles under grazed grassland, enclosed grassland, continuous cropland, rotation cropland and abandoned cropland in the Tianzhu alpine agro-pastoral ecotone. Our results showed that Proteobacteria, Acidobacteria and Actinobacteria were the most three abundant phyla regardless of land use change, accounting for over 60% of the total. Cultivation declined soil bacterial alpha diversity without recovering even after abandonment. Over 73% variations in bacterial diversity can be explained by soil physical and chemical properties. In addition, soil moisture could be the main driver for the difference in bacterial structure between croplands and others. Soil bulk density, pH, organic carbon and total nitrogen contents seem to be the key factors determining the difference in bacterial structure between abandoned croplands and others. Our results have implications for comprehensive understanding about the responses of the soil bacterial community to land use change in alpine regions