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Distributed energy systems are becoming increasingly popular worldwide. The 100% renewable energy system can be an important energy supply alternative to reduce the carbon emissions and address energy shortage, especially for remote areas. However, the performance of 100% renewable energy system (RES) at community level needs further detailed analysis, which is affected by the climates, availability of renewable energy and local energy markets. This paper proposes a design optimization framework of 100% renewable energy systems for low-density communities and investigates the system performance. To investigate the integration and performance of 100% RES, thirty typical cities located in different regions of China were chosen considering different climates, geographical features, and renewable energy distributions. By taking the economic performance as the optimization objective, the optimal design for the 100% RES is obtained, and the energy and economic performance is analyzed. Results show that, under the current energy market conditions, the 100% RES is feasible for low-density communities in most regions of China. The payback periods of the systems in most cities are less than six years. When the cost of PV is reduced by half considering future technological developments, the payback period of a 100% RES can be reduced by 30%–60%. This paper would provide design suggestions and application recommendations in regard to promoting 100% RES in China. • Application of 100% renewable energy system at community level is studied. • 30 zones are selected considering climates, renewable energy sources and markets. • Solar energy and biomass can contribute to over 90% of the total energy supply. • Investment of 100% RES can be paid back in 6 years for most regions. • Payback periods can be reduced by 30%–60% when PV technology is further developed. [ABSTRACT FROM AUTHOR]

In this paper, we calculate the number of spanning trees on two families of generalized pseudo- fractal networks with two controllable parameters. The initial state is a complete graph with an arbitrary number of nodes as a generalization of a triangle. In the subsequent steps, each existing edge (newly produced edge) gives birth to finite new nodes. Using the electrically equivalent transformations, we obtain the changes of edge weights of corresponding equivalent networks and derive the relationships for enumerating spanning trees between original networks and transformed networks. Finally, we obtain closed-form formulas for the number of spanning trees, which is verified by numerical simulations. [ABSTRACT FROM AUTHOR]

From the perspective of strong transitivity, a controller design method is provided to simultaneously stabilise a collection of time-varying linear systems within the framework of nest algebras. In particular, all simultaneously stabilising controllers for a class of linear plants are characterised based on the doubly coprime factorisations. These results hold as well in the time-invariant case. An illustrative example is given to demonstrate the validity of the method. [ABSTRACT FROM PUBLISHER]

Environmental exposure to heavy metal mixture of lead (Pb), cadmium (Cd), and mercury (Hg) would induce hazardous health effects. However, there is a paucity of data on how exposure to heavy metal mixture alters the metabolic dynamics of individual metals. Considering that the dose plays a key role in determining the toxicity of heavy metals, we performed a factorial design with three heavy metals (Pb, Cd, and Hg) at low exposure levels. Female rats were exposed to Pb, Cd, and (or) Hg from successful mating until pup weaning. Their concentrations in maternal blood, breast milk, and postnatal day 0 (PND0) and PND21 offspring blood and whole brain were measured. Using ANOVA analysis, Pearson correlation, and structural equation model, we demonstrated the complex interactions among heavy metals during their absorption, mother-offspring transport, and target organ accumulation. Among all the explored samples, almost all the highest Pb, Cd, and Hg levels were observed in their respective single heavy metal exposure groups. In addition, Hg was found could antagonize the transport of Pb or Cd, when they cross the placental barrier and blood-brain barriers (BBB). However, the effect of Hg no longer presented when they are absorbed through the digestive system. The antagonistic effect of Pb on Cd was observed when they cross the placental barrier. In addition, Cd was also found to compete the transport pathway of Pb when they cross the BBB after birth. Compared to Pb and Hg, we found that the transport efficiency of Cd in the digestive system was lower, whereas the chelation of Cd by the placental barrier was better. This preliminary information may help researchers to explore the mechanism underlying the hazardous effects of heavy metal mixture exposure, or for regulatory agencies to revise guidelines for heavy metal exposure. • Complex interactions were found between lead (Pb), cadmium (Cd), and mercury (Hg) during their transport and absorption. • Hg inhibited Pb or Cd transport when they cross the placenta or blood-brain barrier (BBB) rather than the digestive system. • Pb inhibited Cd transport when they cross the placental barrier while Cd also inhibited Pb transport when they cross the BBB. • Compared to Pb or Hg, the low Cd load in pup benefits by its lower transport efficiency in both placenta and gastrointestinal. [ABSTRACT FROM AUTHOR]