1,945 research outputs found
Are UK Rivers Getting Saltier and More Alkaline?
River salinisation and alkalinisation have become one of the major environmental problems threatening the safety of global freshwater resources. With the accelerated climate change and aggravating anthropogenic influences, it is important to identify the trends and causes of river salinisation and alkalinisation so that better mitigation measures could be taken. This study has focused on the UK rivers because there has been insufficient investigation on this topic. To understand the salinisation and alkalinisation trends and causes of rivers in the UK over the past 20 years from a vertical (analysis of each river) and horizontal (comparison of all rivers) perspective, this study uses the Theil-Sen regression and Mann-Kendall test to deal with the trends of conductivity (proxy on salinisation) and pH (proxy on alkalinisation), obtains outliers of conductivity and pH by boxplot, and calculates the Pearson’s and the Kendall’s Tau correlation coefficients (α = 0.05) between the water quality data and the potential factors (potential road salting, normalized difference vegetation index (NDVI), river discharge, agricultural and urban lands). The results show that the UK rivers are becoming more alkaline with a median pH increase of 0.05 to 0.40, but less salty with a median conductivity decrease of 0.06 to 0.11 mS/cm. And the changes in conductivity and pH have seasonality and regionality, which shows that there are usually greater changes in trends and medians of them in winter or through reaches with more anthropogenic disturbance. Furthermore, from a vertical perspective, the conductivity of more than 50% of rivers in this study is negatively correlated with NDVI and river discharge, and positively correlated with potential road salting, and the pH of that is positively correlated with agricultural lands. While from a horizontal perspective, NDVI and agricultural lands are positively correlated with pH, and potential road salting and urban lands are positively correlated with conductivity. Therefore, road salting, urbanisation, agricultural lands, river discharge and vegetation cover can be considered to affect river salinisation and alkalinisation in the UK
Dual-wavelength domain wall solitons in a fiber ring laser
We report on the experimental observation of a new type of dark soliton in a
fiber laser made of all normal group velocity dispersion fibers. It was shown
that the soliton is formed due to the cross coupling between two different
wavelength laser beams and has the characteristic of separating the two
different wavelength laser emissions. Moreover, we show experimentally that the
dual-wavelength dark solitons have a much lower pump threshold than that of the
nonlinear Schr\"odinger equation dark solitons formed in the same laser.Comment: 19 page
Robust beam splitter with fast quantum state transfer through a topological interface
The Su-Schrieffer-Heeger (SSH) model, commonly used for robust state
transfers through topologically protected edge pumping, has been generalized
and exploited to engineer diverse functional quantum devices. Here, we propose
to realize a fast topological beam splitter based on a generalized SSH model by
accelerating the quantum state transfer (QST) process essentially limited by
adiabatic requirements. The scheme involves delicate orchestration of the
instantaneous energy spectrum through exponential modulation of nearest
neighbor coupling strengths and onsite energies, yielding a significantly
accelerated beam splitting process. Due to properties of topological pumping
and accelerated QST, the beam splitter exhibits strong robustness against
parameter disorders and losses of system. In addition, the model demonstrates
good scalability and can be extended to two-dimensional crossed-chain
structures to realize a topological router with variable numbers of output
ports. Our work provides practical prospects for fast and robust topological
QST in feasible quantum devices in large-scale quantum information processing.Comment: To be published in Frontiers of Physic
Design and Application of Exclusive Service App for Rural Elderly
With the further advancement of rural development and the rapid development of mobile Internet, rural service apps have gradually become an important means of promoting rural economic development and improving farmers’ production and living standards. At present, a number of service-type apps with wide applications in the field of rural services have emerged, such as “Planting Master”, “Farming Network”, “Rural Taobao”, etc. However, these apps do not pay special attention to special groups, but only target the majority of young people and office workers. However, these apps do not pay special attention to special groups, but only target the majority of young people and office workers. In order to fill this gap, we have designed a software called Nong’e Tong, which is specially designed for the elderly and other special groups. The software has a simple and beautiful interface, and is easy to use. It not only provides a lot of special functions, but also can link the elderly’s cell phone with their children’s cell phones to check the health and safety of the elderly at any time. Compared to other software, the application has special features for seniors to ensure that they can use the application easily and quickly
Incorporating Surprisingly Popular Algorithm and Euclidean Distance-based Adaptive Topology into PSO
While many Particle Swarm Optimization (PSO) algorithms only use fitness to
assess the performance of particles, in this work, we adopt Surprisingly
Popular Algorithm (SPA) as a complementary metric in addition to fitness.
Consequently, particles that are not widely known also have the opportunity to
be selected as the learning exemplars. In addition, we propose a Euclidean
distance-based adaptive topology to cooperate with SPA, where each particle
only connects to k number of particles with the shortest Euclidean distance
during each iteration. We also introduce the adaptive topology into
heterogeneous populations to better solve large-scale problems. Specifically,
the exploration sub-population better preserves the diversity of the population
while the exploitation sub-population achieves fast convergence. Therefore,
large-scale problems can be solved in a collaborative manner to elevate the
overall performance. To evaluate the performance of our method, we conduct
extensive experiments on various optimization problems, including three
benchmark suites and two real-world optimization problems. The results
demonstrate that our Euclidean distance-based adaptive topology outperforms the
other widely adopted topologies and further suggest that our method performs
significantly better than state-of-the-art PSO variants on small, medium, and
large-scale problems
A Survey on Approximate Multiplier Designs for Energy Efficiency: From Algorithms to Circuits
Given the stringent requirements of energy efficiency for Internet-of-Things
edge devices, approximate multipliers, as a basic component of many processors
and accelerators, have been constantly proposed and studied for decades,
especially in error-resilient applications. The computation error and energy
efficiency largely depend on how and where the approximation is introduced into
a design. Thus, this article aims to provide a comprehensive review of the
approximation techniques in multiplier designs ranging from algorithms and
architectures to circuits. We have implemented representative approximate
multiplier designs in each category to understand the impact of the design
techniques on accuracy and efficiency. The designs can then be effectively
deployed in high-level applications, such as machine learning, to gain energy
efficiency at the cost of slight accuracy loss.Comment: 38 pages, 37 figure
- …