Water scarcity, land pollution, and global warming are serious challenges and crises facing the development of sustainable or green agriculture and need to be addressed using efficient and ...environmentally friendly management strategies. This paper proposed an integrated framework appropriate for agricultural green total factor productivity (AGTFP) assessment coupled with microscopic and mesoscopic perspectives under water-energy-food (WEF) nexus, which generated scientific and reasonable strategies for green and low-carbon agriculture from internal core factors and peripheral environmental impacts to improve green agricultural production sustainability. Taking the Lianshui irrigation district (LID) with three sub-areas as the object, internal core factors were explored by partial least squares regression (PLSR) and the external impact path through partial least squares structural equation modeling (PLS-SEM). Results indicated that AGTFP in LID was the smallest (0.818) compared to the three sub-areas and was in a fluctuating state. Meanwhile, AGTFP which was calculated considering undesirable outputs, was closer to tangible productivity. Resource endowments and technical facilities will promote agricultural production, desirable outputs will stimulate green production, and undesirable outputs can inhibit green production. The external influence pathway was shown to be primary environment - > secondary environment - > economic aspects - > social aspects - > AGTFP. The innovative perspectives presented in this study can facilitate preferable decisions and avoid unintended consequences for human-natural systems.
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•Established agricultural green total factor productivity (AGTFP) to enhance green production sustainability•The integrated framework amalgamating core with peripheral water-energy-food nexus was constructed.•The slack-based measure directional distance function including undesirable outputs was closely aligned with tangible productivity.•The manipulation of internal input indicators demonstrated superior efficacy compared to output indicators.•The AGTFP was predominantly influenced by the primary and secondary environmental determinants.
Due to the pressure of global ecological degradation, the coordination of economic increase and ecological protection has drawn attention from policymakers and practitioners. Green economic ...efficiency (GEE) is a comprehensive index to measure economic, social, and environmental development. As China is the second-biggest economy in the world with high-energy consumption, it is necessary to investigate its green economy efficiency. In this paper, we innovatively adopt a super-SBM (slacks-based measure) model with undesirable outputs to calculate the GEE in 30 provinces of China between 2008 and 2017, and then comprehensively apply a spatial Dubin model (SDM) to investigated its influencing factors. The results showed that the overall GEE in China during the study period was at a low level with significant regional differences. The inter-regional GEE generally showed a gradient decreasing pattern of “East-Middle-West”, which demonstrates a gradual decline from the East to the West in China. The trend of the national GEE initially dropped and then gradually stabilized over the study period. Foreign trade dependence and direct investment had significant positive effects on the GEE, while the secondary industry and urbanization level had a significant negative effect.
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•Studying the concept of Green Economy Efficiency (GEE)•Coupling the Super-SBM model with the Spatial Dubin Model and Global Moran's I index•Finding the GEE in a gradient decreasing pattern of “East-Middle-West”•Revealing foreign trade dependency and direct investment with positive effects on GEE•Demonstrating secondary industry and urbanization level with significant negative effect
In this paper, spatiotemporal dynamics of broad-area lasers with external optical injection is investigated. We demonstrate theoretically that relatively small optical injection suppresses unstable ...transverse modes and stabilizes laser output. In this paper, the general case of a mismatch in the frequency of the radiation injected and generated by a laser was numerically investigated. It is shown that the frequency mismatch does not destroy the stabilizing effect.
This paper introduces a new model that differentiates between controllable and uncontrollable bad outputs in the measurement of firm performance; the airline industry is used as the empirical ...example. The model allows us to measure technical inefficiency, as well as the inefficiency in the production of bad outputs, and the inefficiency in the investments allocated to the reduction of uncontrollable bad outputs. Moreover, we provide a direct measure of the total cost of controllable bad outputs. As the model involves a number of latent (unobservable) variables that cannot be easily integrated out of the likelihood function without producing complicated expressions, we resort to Bayesian techniques. We find notable differences in inefficiency across airlines. More importantly though, we find that the production of bad or undesirable outputs impose significant costs on airlines. However, these cost issues could be reduced if airlines invest more in maintenance and service training.
This study considers an optimal output anti-synchronisation problem for linear multi-agent systems with non-identical dynamics and antagonistic interactions. It is assumed that the agents are ...non-introspective, i.e. they cannot get their own states or outputs, and can only get a linear combination of relative outputs in the neighbourhood. First, a state transformation is made, which aims at reducing the dimension of the model underlying the output anti-synchronisation errors by removing redundant modes that have no effect on the output anti-synchronisation errors. Then, optimal state feedback controllers are proposed for agents to realise the output anti-synchronisation by constructing discounted performance functions and by solving the discounted algebraic Riccati equation. Moreover, by using an iterative technique, an offline algorithm is provided to solve the linear quadratic tracking problem. In addition, a distributed node-based adaptive observer is proposed to produce an estimate of the state with only relative output information of neighbouring agents by utilising a high-gain approach. The convergence of the proposed adaptive observer is analysed with the help of a Lyapunov function method. Finally, numerical simulations are carried out to demonstrate the effectiveness of the proposed approach.
This study investigates the output consensus problem for a class of non-linear networked multi-agent systems with switching topology and time-varying delays. To synchronise the outputs of the agents, ...novel distributed data-driven consensus protocols are proposed, where the reference input is designed to be the time-varying average of the agents' output. To avoid the self-tracking phenomenon, the delayed information is introduced in the protocol. The proposed methods merely depend on the input and output data of the neighbouring agents, without using explicit or implicit information of its mathematical model. Sufficient conditions are derived to guarantee the closed-loop stability and consensus, with the convergence rate obtained. Numerical and practical examples are conducted to demonstrate the effectiveness of the proposed protocols.
Data envelopment analysis (DEA) is a non-parametric approach for measuring the relative efficiencies of peer decision making units (DMUs). Many studies have examined DEA efficiencies of two-stage ...systems, where all the outputs from the first stage are the only inputs to the second stage. Although single-stage DEA models with undesirable input-outputs have been extensively studied, there still lacks of more systematical investigation on two-stage DEA with undesirable variables. For instance, depending on its operating model, even whether an intermediate variable is desirable or undesirable can be questionable for a particular two-stage system. Furthermore, most of the existing studies on two-stage systems focus on the case where only the final outputs are undesirable. In this work, we try to systematically examine two-stage DEA models with undesirable input-intermediate-outputs. Particularly, we utilize the free-disposal axioms to construct the production possibility sets (PPS) and the corresponding DEA models with undesirable variables. The proposed models are then used to illustrate some theoretical perspectives by using the data of China׳s listed banks.
•We investigate two-stage DEA models with undesirable input-intermediate-outputs.•We use the free-disposal axioms to construct production possibility sets. We construct two-stage network DEA models with undesirable indexes.•The new approach is applied to evaluate the efficiencies of China׳s listed banks.
A freestanding conducting polymer plate with one side forming a Schottky contact and the other side an Ohmic contact with two different metal electrodes can generate a DC voltage with an output ...current density as high as 218.6 μA cm−2 upon mechanical deformation.
Output power and beam quality are the two main bottlenecks for semiconductor lasers—the favourite light sources in countless applications because of their compactness, high efficiency and cheapness. ...Both limitations are due to the fact that it becomes increasingly harder to stabilize a single-mode laser over a broader chip area without multi-mode operations. Here we address this fundamental difficulty with the Dirac-vortex topological cavity1, which offers the optimal single-mode selection in two dimensions. Our topological-cavity surface-emitting laser (TCSEL) exhibits 10 W peak power, sub-1° divergence angle and 60 dB side-mode suppression, among the best-reported performance ever at 1,550 nm—the most important telecommunication and eye-safe wavelength where high-performance surface emitters have always been difficult to make2. We also demonstrate the multi-wavelength capability of two-dimensional TCSEL arrays that are not generally available for commercial lasers2,3. TCSEL, as a new-generation high-brightness surface emitter, can be directly extended to any other wavelength range and is promising for an extremely wide variety of uses.Researchers demonstrate a topological-cavity surface-emitting laser with a 10 W peak power and sub-degree beam divergence at 1,550 nm wavelength. The system is also capable of multiple-wavelength arrays.