On an optimization problem related to static super-replicating strategies

In this paper, we investigate an optimization problem related to super-replicating strategies for European-type call options written on a weighted sum of asset prices, following the initial approach in Chen et al. (2008). Three issues are investigated. The first issue is the (non-)uniqueness of the optimal solution. The second issue is the generalization to an optimization problem where the weights may be random. This theory is then applied to static super-replication strategies for some exotic options in a stochastic interest rate setting. The third issue is the study of the co-existence of the comonotonicity property and the martingale property.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Trajectory tracking control of a hydraulic-tendon actuator with an application to the exoskeleton

This paper presents a hydraulic actuator and tendon drive system that was specifically designed for a lower-limb exoskeleton to provide high power and low inertia. The dynamics of the actuator-tendon system were analyzed based on the exoskeleton system and an adaptive sliding-mode trajectory tracking controller was designed for the drive system. The stability proof indicates that the controller is globally stable. The experimental results demonstrated that the controller provides high tracking accuracy and is robust to external disturbances and unmodeled nonlinearities. Moreover, the controller has less errors than the conventional PID controller. Further tests that included the joints of the exoskeleton were conducted to verify the performance of the controller

Evolution and focal features of China’s agricultural green development policies: Text analysis based on attention perspective

[Objective] Green development is an important direction for the structural reform and transformation and upgrading of modern agriculture. Exploring the evolution of government attention to policies on agricultural green development can provide theoretical references for future policy formulation and implementation. [Methods] From the perspective of attention, combined with the theoretical model of punctuated equilibrium, this study applied text mining methods such as high-frequency word identification, co-occurrence word analysis, and keyword clustering through Python to analyze 1535 policy documents related to agricultural green development from 1984 to 2022. [Results] The study found that: (1) From the historical evolution of attention allocation, it can be seen that China’s agricultural green development policies have experienced three stages: exploration, construction, and consolidation and deepening. There were differences in the focus of government attention to agricultural green development policies in different periods; leading enterprises were important subjects for promoting agricultural transformation, upgrading, and green development. (2) From the perspective of focus configuration, China’s agricultural green development began with a top-down system engineering aimed at protecting the ecological environment. Technological innovation ran through the entire process of government attention to agricultural green development, and was the fundamental driving force for agricultural transformation, upgrading, and green development. [Conclusion] With the proposal of the rural revitalization strategy, the economic benefits in the process of agricultural green development are becoming increasingly prominent, and local governments should actively explore new paths and new methods of the integration of agricultural production and agricultural tourism under the premise of meeting the needs of ecological civilization construction, and take leading enterprises as the traction to help the industrialized operation of households in rural areas, and boost the green transformation and upgrading of China’s agriculture and high-quality development

Structure-dependent electrical properties of graphene nanoribbon devices with graphene electrodes

Graphene nanoribbons (GNRs) are a novel and intriguing class of materials in the field of nanoelectronics, since their properties, solely defined by their width and edge type, are controllable with high precision directly from synthesis. Here we study the correlation between the GNR structure and the corresponding device electrical properties. We investigated a series of field effect devices consisting of a film of armchair GNRs with different structures (namely width and/or length) as the transistor channel, contacted with narrowly spaced graphene sheets as the source-drain electrodes. By analyzing several tens of junctions for each individual GNR type, we observe that the values of the output current display a width-dependent behavior, indicating electronic bandgaps in good agreement with the predicted theoretical values. These results provide insights into the link between the ribbon structure and the device properties, which are fundamental for the development of GNR-based electronics.Comment: Published in Carbon (2019