307 research outputs found
Do foreign institutional investors drive corporate social responsibility? Evidence from listed firms in China
This paper investigates the effect of qualified foreign institutional investors (QFIIs) on corporate social responsibility (CSR) within the context of listed firms in China. We find that QFIIs offer an incisive channel for improving socially responsible practices. In addition, we find that firms with QFIIs are more likely to comply with the Global Reporting Initiative (GRI) guidelines, and that their sustainability reports tend to be longer. We also find that this positive effect is more pronounced in firms with low initial CSR scores than those with high CSR scores at the time when QFIIs enter the sample. Our empirical evidence further confirms that this positive impact is driven by QFIIs from countries with high social awareness, or QFIIs from geographically distant countries, consistent with their motives, and is linked to the ownership of QFIIs, especially when the QFII is among the top ten of the largest shareholders. Finally, our extended analysis reveals that the increase in CSR performance associated with the presence of QFIIs results in greater firm performance and easier access to finance
Terahertz scale microbunching instability driven by nonevaporable getter coating resistive-wall impedance
Non-evaporable getter (NEG) coating is widely required in the next generation
of light sources and circular colliders for small vacuum pipes to
improve the vacuum level, which, however, also enhances the high-frequency
resistive-wall impedance and often generates a resonator-like peak in the
terahertz frequency region. In this paper, we will use the parameters of the
planned Hefei Advanced Light Facility (HALF) storage ring to study the impact
of NEG coating resistive-wall impedance on the longitudinal microwave
instability via particle tracking simulation. Using different NEG coating
parameters (resistivity and thickness) as examples, we find that the impedance
with a narrow and strong peak in the high frequency region can cause
micro-bunching instability, which has a low instability threshold current and
contributes to a large energy spread widening above the threshold. In order to
obtain a convergent simulation of the beam dynamics, one must properly resolve
such a peak. The coating with a lower resistivity has a much less sharp peak in
its impedance spectrum, which is helpful to suppress the micro-bunching
instability and in return contributes to a weaker microwave instability
Existence and nonexistence of solutions to a critical biharmonic equation with logarithmic perturbation
In this paper, the following critical biharmonic elliptic problem
\begin{eqnarray*} \begin{cases} \Delta^2u= \lambda u+\mu u\ln
u^2+|u|^{2^{**}-2}u, &x\in\Omega,\\ u=\dfrac{\partial u}{\partial \nu}=0,
&x\in\partial\Omega \end{cases} \end{eqnarray*} is considered, where
is a bounded smooth domain with . Some
interesting phenomenon occurs due to the uncertainty of the sign of the
logarithmic term. It is shown, mainly by using Mountain Pass Lemma, that the
problem admits at lest one nontrivial weak solution under some appropriate
assumptions of and . Moreover, a nonexistence result is also
obtained. Comparing the results in this paper with the known ones, one sees
that some new phenomena occur when the logarithmic perturbation is introduced
Phase Equilibria and Phase Separation of the Aqueous Solution System Containing Lithium Ions
Brines including seawater, concentrated seawater after desalinization, salt lake, oil/gas water, and well bitter are widely distributed around the world. In order to promote the comprehensive utilization and effective protection of the valuable chemical resources existing in brines such as freshwater, lithium, sodium, potassium, and magnesium salts, the systematic foundation and application foundation research including phase equilibria and thermodynamic properties for the salt‐water electrolyte solution are essential, especially for solid lithium salts and their aqueous solution systems
Adaptive multimodal continuous ant colony optimization
Seeking multiple optima simultaneously, which multimodal optimization aims at, has attracted increasing attention but remains challenging. Taking advantage of ant colony optimization algorithms in preserving high diversity, this paper intends to extend ant colony optimization algorithms to deal with multimodal optimization. First, combined with current niching methods, an adaptive multimodal continuous ant colony optimization algorithm is introduced. In this algorithm, an adaptive parameter adjustment is developed, which takes the difference among niches into consideration. Second, to accelerate convergence, a differential evolution mutation operator is alternatively utilized to build base vectors for ants to construct new solutions. Then, to enhance the exploitation, a local search scheme based on Gaussian distribution is self-adaptively performed around the seeds of niches. Together, the proposed algorithm affords a good balance between exploration and exploitation. Extensive experiments on 20 widely used benchmark multimodal functions are conducted to investigate the influence of each algorithmic component and results are compared with several state-of-the-art multimodal algorithms and winners of competitions on multimodal optimization. These comparisons demonstrate the competitive efficiency and effectiveness of the proposed algorithm, especially in dealing with complex problems with high numbers of local optima
MPR-Net:Multi-Scale Pattern Reproduction Guided Universality Time Series Interpretable Forecasting
Time series forecasting has received wide interest from existing research due
to its broad applications and inherent challenging. The research challenge lies
in identifying effective patterns in historical series and applying them to
future forecasting. Advanced models based on point-wise connected MLP and
Transformer architectures have strong fitting power, but their secondary
computational complexity limits practicality. Additionally, those structures
inherently disrupt the temporal order, reducing the information utilization and
making the forecasting process uninterpretable. To solve these problems, this
paper proposes a forecasting model, MPR-Net. It first adaptively decomposes
multi-scale historical series patterns using convolution operation, then
constructs a pattern extension forecasting method based on the prior knowledge
of pattern reproduction, and finally reconstructs future patterns into future
series using deconvolution operation. By leveraging the temporal dependencies
present in the time series, MPR-Net not only achieves linear time complexity,
but also makes the forecasting process interpretable. By carrying out
sufficient experiments on more than ten real data sets of both short and long
term forecasting tasks, MPR-Net achieves the state of the art forecasting
performance, as well as good generalization and robustness performance
A maximal clique based multiobjective evolutionary algorithm for overlapping community detection
Detecting community structure has become one im-portant technique for studying complex networks. Although many community detection algorithms have been proposed, most of them focus on separated communities, where each node can be-long to only one community. However, in many real-world net-works, communities are often overlapped with each other. De-veloping overlapping community detection algorithms thus be-comes necessary. Along this avenue, this paper proposes a maxi-mal clique based multiobjective evolutionary algorithm for over-lapping community detection. In this algorithm, a new represen-tation scheme based on the introduced maximal-clique graph is presented. Since the maximal-clique graph is defined by using a set of maximal cliques of original graph as nodes and two maximal cliques are allowed to share the same nodes of the original graph, overlap is an intrinsic property of the maximal-clique graph. Attributing to this property, the new representation scheme al-lows multiobjective evolutionary algorithms to handle the over-lapping community detection problem in a way similar to that of the separated community detection, such that the optimization problems are simplified. As a result, the proposed algorithm could detect overlapping community structure with higher partition accuracy and lower computational cost when compared with the existing ones. The experiments on both synthetic and real-world networks validate the effectiveness and efficiency of the proposed algorithm
Integrating non-planar metamaterials with magnetic absorbing materials to yield ultra-broadband microwave hybrid absorbers
Broadening the bandwidth of electromagnetic wave absorbers has greatly challenged material scientists. Here, we propose a two-layer hybrid absorber consisting of a non-planar metamaterial (MM) and a magnetic microwave absorbing material (MAM). The non-planar MM using magnetic MAMs instead of dielectric substrates shows good low frequency absorption and low reflection across a broad spectrum. Benefiting from this and the high frequency strong absorption of the MAM layer, the lightweight hybrid absorber exhibits 90% absorptivity over the whole 2-18 GHz range. Our result reveals a promising and flexible method to greatly extend or control the absorption bandwidth of absorbers. (C) 2014 AIP Publishing LLC
Lithium Recovery from Brines Including Seawater, Salt Lake Brine, Underground Water and Geothermal Water
Demand to lithium rising swiftly as increasing due to its diverse applications such as rechargeable batteries, light aircraft alloys, air purification, medicine and nuclear fusion. Lithium demand is expected to triple by 2025 through the use of batteries, particularly electric vehicles. The lithium market is expected to grow from 184,000 TPA of lithium carbonate to 534,000 TPA by 2025. To ensure the growing consumption of lithium, it is necessary to increase the production of lithium from different resources. Natural lithium resources mainly associate within granite pegmatite type deposit (spodumene and petalite ores), salt lake brines, seawater and geothermal water. Among them, the reserves of lithium resource in salt lake brine, seawater and geothermal water are in 70–80% of the total, which are excellent raw materials for lithium extraction. Compared with the minerals, the extraction of lithium from water resources is promising because this aqueous lithium recovery is more abundant, more environmentally friendly and cost-effective
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