This paper introduces an evolutionary algorithm, Shuffled Frog Leaping Algorithm (SFLA), to solve the optimization problem in designing the multi-pumped Raman Fibre Amplifier (RFA). SFLA is a powerful optimizer tool because of its efficient mathematical expressions and global search capability. We utilize SFLA to determine the optimal pump wavelengths and pump powers by minimizing the gain ripple of RFA. To accelerate calculations, a terminal value optimization strategy (TVOS) is incorporated into the evolution of SFLA. This proposed strategy takes the terminal power values of pumps as the decision variables in optimization. Then, the optimal original power values of the pumps are obtained by solving the Power Coupled Equations once, without using the traditional method of repetitive guesses.The combination of SFLA and TVOS enhances the efficiency of optimization and accelerates calculation, while satisfying the design requirements of RFA.The simulation results show that nearly 65% of computational time has been saved compared with the traditional average power analysis. The 4-pumped C+L band of backward multi-pumped RFA with the average net gain of 0 dB, 1 dB and 2 dB are designed individually, where the gain ripple is less than 0.64 dB. The combination of SFLA and TVOS enhance the optimization efficiency and improve the performance of RFA with good gain profile.
Understanding the evolution of lakes in arid areas is very important for water resource management. Previous studies have mainly focused on lakes with runoff recharge, while the evolution of groundwater recharge lakes in hyper-arid areas is still less known. In this study, an 86 cm-long sediment core was extracted from Sayinwusu Lake, one of groundwater-recharge lakes in the southeastern Badain Jaran Desert, Northwest China. 210 Pb and 137 Cs dating, total organic carbon (TOC) and total nitrogen (TN) contents, and mineral content analysis were used to reconstruct the lake evolution over the past 140 years. The evolution of Sayinwusu Lake since 1880 can be divided into two periods. In the first period from 1880 to 1950, the TOC and TN contents were low, and the minerals consisted of all detrital minerals, which indicate that the lake’s primary productivity and salinity were low. During the second period from 1950 to 2018, the contents of TOC, TN, and carbonate minerals increased rapidly at the beginning of the 1950s, indicating that the lake’s primary productivity and salinity increased. Comprehensive analysis of regional climate data suggests that the increase in evaporation caused by rising temperature is an important factor affecting lake evolution in the desert. Although precipitation has increased in the arid region of Northwest China in recent decades with increasing temperature, the enhancement of the evaporation effect is much greater. As a record from groundwater recharge lakes in deserts, our study provides new insight into projecting future lake changes in hyper-arid areas.
This study proposes a model to investigate brand advocacy in the context of higher education marketing. The model examines the impact of social media marketing, instructor behaviour, reputation, and brand personality on engagement and subsequent brand advocacy. Data were collected from a China sample. The study revealed that social media marketing, instructor behaviour, reputation, and brand personality exert a positive impact on student engagement, which subsequently translates into brand advocacy. The moderating role of value congruity and altruism is verified. The findings provide higher education institution administrators with some guidelines to strategize their marketing and branding communication to foster engagement and brand advocacy.
In palaeolimnology, microfossils play an important role as ecological indicators of lake history. A reliable interpretation of microfossil data requires a comprehensive understanding of transport processes as well as determining whether microfossil assemblages are representative of their living communities. The occurrence of transport in ostracod taphocoenoses can be identified from the population age structure of valves. In this study, 23 surface sediment samples from Dalongchi Lake, northwestern China, were analysed for species composition, and 16 were also analysed for the population age structure of Fabaeformiscandona gyirongensis. Ostracod valves are dominated by F. gyirongensis, with frequently occurring Ilyocypris sp. in the surface sediments. The distribution and abundance of ostracods are significantly correlated with the sampling depth and grain size, implying that hydrological conditions are the major controlling factor. The dominant species F. gyirongensis seems to prefer relatively deep and stable lacustrine conditions, while Ilyocypris sp. seems to prefer shallow conditions with rich submerged macrophytes and relatively coarse substrate in Dalongchi Lake. The spatial changes in the population age structure of F. gyirongensis match the different hydrodynamic regimes within the lake, with abundant early and middle instars in deeper waters and abundant middle and late instars in shallower waters, denoting that downslope transport of valves may be responsible for the spatial changes in the population structure. Our findings, together with previous works, indicate that downslope transport of instars and subsequent depth differentiation of the population structure of ostracods can occur for different species in both marine and lacustrine settings, which potentially leads to some biases based on the "in situ" inference of microfossils in palaeoenvironmental reconstruction. Hence, careful transport process assessment of fossil assemblages based on population age structure and other characteristics, such as the ratios of adults to juveniles and carapaces to valves, is a valuable prerequisite for palaeoenvironmental analysis.
Limnocythere inopinata (Baird, 1843) is a widely distributed ostracod in modern non-marine waters and Quaternary sediments. Based on its morphological variation (the number and position of its nodes), different phenotypes have been identified. However, the factors controlling its morphological variation are currently open to debate, which hinders palaeoecological reconstructions based on this species. In this study, ostracod distribution and hydrochemical analyses of the ambient environment of 21 lakes in the Badain Jaran Desert were carried out. Three ostracod species belonging to two genera are identified as Limnocyhtere inopinata, Cypris cf. granulate and Cypris sp. with the dominant species L. inopinata represented by six phenotypes. The distribution features of these ostracods in the lakes and related ecological information are reported. In addition, the factors controlling the morphological variations of L. inopinata were analysed. Our data indicate that the noded individuals of L. inopinata prefer water with appropriate Ca2+ content (30–40 mg L−1) and low salinities (below 4.60 g L−1). The percentage of noded individuals of L. inopinata increases with increasing salinity only within a certain salinity range. Hence, caution should be exercised in reconstructions of palaeosalinity based on the morphological variability of L. inopinata.
Although the MPB composition 0.42PNN-0.21PZ-0.37PT ceramic has high piezoelectric properties, its temperature stability at room temperature is rather poor due to the low phase-transition temperature. By texture engineering using BaTiO3 (BT) as the template, the temperature stability of this material can be greatly improved. In the temperature range from room temperature up to 140 °C, the high effective piezoelectric strain constant d33* of 0.42PNN-0.21PZ-0.37PT-3BT only changed by 4.9% from 1278 to 1215 pm/V, while the d33* of the nontextured counterpart changed by 46.7% from the room temperature value of 920 pm/V with the maximum deviation to 1350 pm/V at 80 °C. In addition, the textured ceramic has higher piezoelectric properties, lower dielectric loss, and slightly higher coercive field. The room-temperature figure-of-merit d33 × g33 for PNN-PZT-2BT is increased by as much as 42% compared with the nontextured counterpart. Our results demonstrated that texture engineering is an effective way to improve the temperature stability of the MPB composition piezoceramics.
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