Diesel generator (DG)–battery power systems are often adopted by telecom operators especially in semi-urban and rural areas of developing countries. System dispatch is one of the key factors to hybrid power system integration. The contradiction between battery dispatch and DG dispatch in DG–battery power systems is that shallow and medium cycling is preferred for long battery life, while deep cycling is preferred for DG fuel and maintenance saving. In this paper, two dispatch regimes, A of full cycle charge strategy and B of partial state of charge (PSOC) strategy, and the corresponding SOC (state of charge) set points of the DG–battery power system are analysed and compared in terms of system operational expenditure (OPEX) and net present cost (NPC). The system OPEX mainly consists of fuel-related, filters-related and battery bank replacement costs. The simulation programme is established based on system efficiency calculations and battery charging regimes. The results show that (1) shallow cycling may bring long DG running time and high fuel consumption, while deep cycling is in favour of reducing DG running time and fuel consumption; (2) shallow cycling is in favour of battery life under Regime A, while deep cycling is in favour of battery life under Regime B; (3) depth of discharge (DOD)[0.8, 1.0] leads to the lowest NPC for both Regime A and Regime B; (4) Regime B wins with not large difference before the battery bank replacement happened, and after then Regime A wins.
Scientific models play a vital role in science learning, representing major characteristics of scientific phenomena. A useful visualization of models that matches target concepts to source objects can facilitate students’ learning of abstract and complex structures of chemical elements and compounds. This report will show the importance of visualization and innovative technology (such as augmented reality), which has the potential of supporting students’ learning of stereochemistry and interactions among molecules. Examples (including organic compounds, chemical elements of 1A and 7A in the periodic table, water polarity, and carbon nanotube) are drawn to illustrate the potential use of augmented reality in chemistry instruction.
Background: Cardiac extra-cellular matrix (ECM) fibrosis plays an important role in the pathophysiology of heart failure (HF). It may provide electrical heterogeneity and a substrate for arrhythmogenicity, which may cause sudden cardiac death (SCD).
Methods: Twenty-one patients with manifestations of HF and a left ventricular ejection fraction (LVEF) ≤50% were enrolled. The median age was 62 years and median LVEF was 33%. Time- and frequency-domain analysis of heart rate variability (HRV) on 24 h ambulatory electrocardiography recording was assessed. Serum markers of ECM turnover including type I and III aminoterminal propeptide of procollagen (PINP and PIIINP), matrix metalloproteinase-2 and -9 (MMP-2 and MMP-9), and tissue inhibitor of metalloproteinase-1 (TIMP-1) were analyzed.
Results: The serum PIIINP concentration was correlated significantly with standard deviation of all normal to normal R-R intervals (SDNN) (r=–0.722, p=<0.001), percentage of adjacent NN interval differences >50 ms (pNN50) (r=–0.528, p=0.014), percentage of adjacent NN interval differences >20 ms (pNN20) (r=–0.545, p=0.002), very low frequency (VLF) (r=–0.490, p=0.024), low frequency (LF) (r=–0.491, p=0.024), and high frequency (HF) (r=–0.513, p=0.018). PINP, MMP-2, -9, TIMP-1 were not correlated with time- and frequency-domain analysis of HRV.
Conclusions: PIIINP was significantly correlated with time- and frequency-domain analysis of HRV in HF patients. PIIINP is a potential serological marker to evaluate cardiac autonomic control and risk of SCD in HF patients.