太阳能光伏光热(PV/T)系统在建筑中的应用研究

"碳达峰、碳中和"目标下,可再生能源在建筑中的应用受到越来越多的重视.在诸多可再生能源中,太阳能作为最容易与建筑结合的可再生能源之一,具有清洁、安全、稳定、高效等特点,对其深入开发利用是未来建筑能源结构性改革的需求.本文对国内外太阳能光伏光热系统的技术最新发展现状进行了梳理和总结,研究了太阳能光伏光热(PV/T)系统在建筑中的应用方式,分析了太阳能光伏光热系统的典型案例与发展趋势,为实现产业升级、降低成本、扩大应用提供参考.     

General Aspects of the Combustion Synthesis of a Cobalt Alloy with Dispersion and Precipitation Modification

Inorganic Materials - We have studied the potentialities of dispersion and precipitation modification of a cobalt alloy in combustion mode under the effect of centrifugal forces. The starting...     

振动法在纤维增强材料结构探伤中的应用

本文通过建立纤维增强材料的有限元模型及模态测试,以模态比例因子为目标参数,修正有限元模型.采用模态力留数的方法,实现对纤维增强结构的无损探伤.为验证方法的有效性,采用人为添加附加质量的方法,测试附加质量前后的模态振型,通过模态力留数,显示故障点位置及实验数据,能准确识别出添加质量点的位置.     

Efficient reliability analysis of dynamic k-out-of-n phase-AND mission systems

Motivated by real-world applications of satellites and wireless sensor networks, this paper models and evaluates a dynamic k-out-of-n phase-AND mission system (k/n-PAMS). The mission task conducted by a k/n-PAMS involves multiple consecutive phases; the mission is successful as long as the task is successful in any of the phases. Due to factors, such as scheduled maintenance, location changes in task execution during different phases, and resource sharing with other tasks, the total number of available components n for the considered mission task and the required number of working components k may change from phase to phase. In addition, due to varying load and working environments, component failure time distributions are also phase dependent. This paper proposes an analytical modeling approach based on multivalued decision diagrams (MDDs) for assessing reliability of the considered k/n-PAMS. The approach encompasses a new and fast MDD model generation algorithm that considers behaviors of all the mission phases simultaneously based on node labeling. As demonstrated through empirical studies on k/n-PAMSs with different sizes (different numbers of phases and different numbers of system components), the proposed algorithm is more efficient than the traditional phase-by-phase model generation method.     

Growth inhibition of Fusarium graminearum and deoxynivalenol detoxification by lactic acid bacteria and their application in sourdough bread

Eight lactic acid bacteria (LAB) strains were screened for their ability to inhibit Fusarium graminearum (F. graminearum) growth and remove deoxynivalenol (DON). Furthermore, the selected LAB strains were applied as starter cultures to evaluate their performance during the breadmaking process. Lactobacillus plantarum (L. plantarum) AR524 exhibited strong inhibitory activity against F. graminearum growth in a pH-dependent manner and removed up to 40.9% of DON, mainly through cell wall binding. Compared with the control, L. plantarum AR524 inhibited 60.19% of F. graminearum growth and removed 50.53% of DON during breadmaking. The texture properties of the bread were also remarkably improved by L. plantarum AR524, and its shelf life was extended from 3 days to 6 days without the application of any chemical preservatives. Therefore, L. plantarum AR524 shows excellent potential for application as a bioprotective starter culture in bakery products.     

Influence of bio-clogging on permeability characteristics of soil

It is necessary to enhance the barrier performance of cutoff walls in order to improve the contamination control level, especially for reconstruction or expansion of existing landfill sites. This paper presents a comprehensive laboratory investigation on the synergistic effects of microorganisms and fibers on the hydraulic conductivity of silty sand to evaluate the applicability to the field condition as an alterative barrier material. Inside the soil, the added carbon fibers not only provided good biocompatibility, but also formed spatial three-dimensional network between soil particles to improve the bacterial adhesion that eventually caused 2–3 orders of magnitude decrease in soil permeability. The resistance of the biofilm to extreme conditions was tested by permeation with solutions of different salinity and pH values, and by subjecting specimens to various hydraulic gradients and soil conditions. Despite the microbial growth inhibition occurred at these conditions, however, biofilm can largely remain intact and continue to reduce k, which due to the gradual adaptation of microorganisms to the extreme environment and the gradual recovery of their activity. Results of these tests demonstrate that biofilm treatment may be a feasible technology for creating waste containment barriers in soil.     

Ligand-free Au nanoclusters/g-C3N4 ultra-thin nanosheets composite photocatalysts for efficient visible-light-driven photocatalytic H2 generation

In this paper, we report the synthesis of ligand-free Au nanoclusters (NCs)/g-C₃N₄ ultra-thin nanosheets (NSs) composite via a facile wet-impregnation method with post-annealing. On the one hand, post-annealing was used for the exfoliation of multi-layered g-C₃N₄ to obtain ultra-thin NSs; on the other hand, after Au₂₅(Cys)₁₈ NCs were loaded, post-annealing was further adopted to remove the ligands to obtain clean surface on Au NCs. It is demonstrated that the loaded Au NCs were aggregating resistant by post-annealing. Constructing heterojunctions with appropriate inter-band structures between the ligand-free Au NCs and the ultra-thin g-C₃N₄ NSs, along with the mono-distribution of the Au NCs and their intimate contact with g-C₃N₄ NSs ensured the smooth interfacial charge transfer. As a result, the composite photocatalysts exhibited efficient visible-light-induced photocatalytic H₂ generation, mainly due to the local electric field enhancement induced by excitation of Au NCs under visible light and the improved charge separation in g-C₃N₄. This work provides a general strategy for the synthesis of noble metal NCs based composites with clean surface as the efficient photocatalysts for solar energy conversion.

Graphical Abstract

A stepwise post-annealing strategy is exploited to prepare g-C₃N₄ ultra-thin nanosheets modified with highly dispersed ligand-free Au nanoclusters for efficient photocatalytic hydrogen production.

     

An optional connection material in timber structures: densified poplar

The development of eco-friendly connection material instead of steel is a challenging problem in timber structures. Following densification, the mechanical properties of low-density species can be significantly improved. Densified wood may be a potential connection material in timber structures. This paper reviewed the different processing for densified wood, and obtained favorable mechanical properties and dimensional stability based on small specimen sizes, which are much less than the applicable sizes in practice. A densification processing with alkali pretreatment was adopted for poplar widely cultivated in the world to produce the densified poplar, which has been rarely reported as connection material. Various specimens of densified poplar were tested to obtain their main mechanical properties such as strength and deformability. The set recovery of densified poplar was also measured to observe their dimensional stability. In addition, the hygroscopic swelling strains for the diameter of densified poplar dowel were measured to present their moisture-dependent behavior. The improved mechanical properties and dimensional stability confirmed the fact that densified poplar with alkali pretreatment can be an optimal connection material.

Graphical abstract

     

Smart fabric strain sensor comprising reduced graphene oxide with structure-based negative piezoresistivity

Journal of Materials Science - Fabric strain sensors have attracted significantly increased interest as wearable electronics for their flexibility, softness, and wearing comfort in recent years....