The role of tourism in China’s economic system and growth. A social accounting matrix (SAM)-based analysis

After the opening policy in 1978, China’s tourism increasingly took relevance, up to become an important industry in the last two decades. Despite this, no analysis has been conducted at macroeconomic level to check both tourism industry interdependencies and wealth creation. To fill this gap, in this paper we elaborated an innovative conceptual model for the theory-based analysis of the tourism phenomenon in China, having the Keynesian macroeconomic theory as the background and using an SAM as the model accounting representation, and conducted an original, comprehensive methodological analysis of China’s tourism industry. As the database, we used a purposively elaborated 2015 SAM for China with 19 industries, on whose basis we identified endogenous and exogenous accounts, set up an innovative impact multiplier model adjusted to them and conducted an economic analysis of tourism interdependencies never performed so far. Evidence shows that manufacturing, agriculture and trade industries provide a relevant support to tourism services production, and that tourism greatly contributes to value added/GDP and household income creation. Overall, tourism industry has direct policy management implications, representing a sector on which enterprises and government can profitably base their decisions, with exogenous tourism demand shocks positively activating China’s economic system and growth

Conductance crossovers in coherent surface transport on y nanojunctions

Conductance characteristics of a nonplanar two-dimensional electron gas (2DEG) can expose the role of its bending on the 2DEG electronic states. In particular, the presence of an effective geometric potential can be revealed. Here, we present a numerical study of the coherent electron transport on Y nanojunctions of three cylindrical 2DEGs, including a proposal for the experimental detection of the geometric potential. We describe the analytical approach leading to the reduction of the problem dimensionality from 3D to 2D and sketch our simulation scheme. © 2009 IOP Publishing Ltd

Mixed Integer Linear Program model for optimized scheduling of a vanadium redox flow battery with variable efficiencies, capacity fade, and electrolyte maintenance

Redox Flow Batteries are a promising option for large-scale stationary energy storage. The vanadium redox flow battery is the most widely commercialized system thanks to its chemical stability and performance. This work aims to optimize the scheduling of a vanadium flow battery that stores energy produced by a renewable power plant, keeping into account a thorough characterization of the battery performance, with variable efficiencies and capacity fade effects. A detailed characterization of the battery performance improves the calculation of the optimal number of cycles and revenue associated with the battery use if compared to the results obtained using simpler models, which take into account constant efficiencies and no capacity fade effects. The presented problem is nonlinear due to the functions of the battery efficiency, which depend upon charging and discharging powers and state of charge with nonlinear, non-convex correlations. The problem is linearized using convex hulls. The optimization program also calculates the progressive battery capacity fade due to undesired secondary electrochemical reactions and the economic impact of capacity restoration through periodic maintenance. The final problem is solved as a Mixed-Integer Linear Program (MILP) to guarantee the global optimality of the linearized problem. The proposed optimization model has been applied to two different case studies: a case of energy arbitrage and a case of load-shifting. The optimization results have been compared to those obtained with constant battery efficiency models, which do not consider the capacity fade effects. Results show that simpler models overestimate the optimal number of cycles of the battery and the revenue by up to 15% if they do not take into account the degradation model of the battery, and respectively up to 32% and 42% if they also assume constant efficiency for the battery

Electronic and magnetic states in core multishell nanowires: Edge localization, Landau levels and Aharonov-Bohm oscillations

We study the electronic states of hexagonal core multishell semiconductor nanowires, including the effect of magnetic fields. We find that the two dimensional electron states formed at the interface between different layers are mostly localized at the six edges of the hexagonal prism, and behave as a set of quasi-1D quantum channels. They can be manipulated by magnetic fields either parallel or perpendicular to the wire axis. These results can be rationalized in terms of Aharonov-Bohm oscillations or Landau level formation. We also show that inter-channel coupling and magnetic behavior is influenced by the geometric details of the nanowires. © 2009 IOP Publishing Ltd

SET, A SCENARIO EVALUATOR TOOL FOR SUPPORTING SPACE-EXPLORATION MISSION-ARCHITECTURE DESIGN

The design of space-exploration missions begins with a mission statement that defines the ultimate goals of the mission itself. The mission-architecture defines, instead, how the mission will work in practice, and encompasses all the elements that will take part in it. It includes such issues as the synergies of manned and robotic resources, mission control, and the mission timeline. The mission-architecture design activity is an iterative process in general aimed at the maximization of the cost effectiveness (or value) of the mission and minimization of costs. This is performed by successive comparisons and evaluation of the alternative generated mission architectures. The Scenario Evaluator Tool (SET) is conceived to support the engineering team in the framework of the space mission design process. In particular, SET is a simulation software tool that allows building mission architectures with a significant reduction of development time and computational effort. The software allows the characterization, the comparison, and optimization of exploration scenarios and building blocks through a user friendly graphical interface. Each mission-architecture is characterized and evaluated on the basis of the mass budget of the building blocks, cost index and exploration capabilities. SET is general enough to allow the design of several space exploration scenarios for Gap-analysis studies (flexibility). Further, it allows the users to introduce new model libraries (expandability). This paper describes the main features and the potentialities of the simulation software. To show the working principle of SET, a hypothetical human space-exploration mission scenario has been developed and implemented. The results has been accomplished in the framework of STEPS (Systems and Technologies for the ExPloration of Space), which is a research project co-financed by Piedmont Region (Italy), firms and universities of the Piedmont Aerospace District

Magnetic states in prismatic core multishell nanowires

We study the electronic states of core multi-shell semiconductor nanowires, including the effect of strong magnetic fields. We show that the multi-shell overgrowth of a free-standing nanowire, together with the prismatic symmetry of the substrate, may induce quantum confinement of carriers in a set of quasi-1D quantum channels corresponding to the nanowire edges. Localization and inter-channel tunnel coupling are controlled by the curvature at the edges and the diameter of the underlying nanowire. We also show that a magnetic field may induce either Aharonov-Bohm oscillations of the energy levels in the axial configuration, or a dimensional transition of the quantum states from quasi-1D to Landau levels for fields normal to the axis. Explicit predictions are given for nanostructures based on GaAs, InAs, and InGaN with different symmetries.Comment: 13 pages, 4 figures, To be published in Nano Letter

techno economic sizing of a battery energy storage coupled to a wind farm an italian case study

Abstract The study focuses on the technical and economic issues which arise when a battery energy storage is coupled to a wind farm to improve its profitability. The electric energy storage technologies may fulfil the dual role of promoting the renewable energy sources development and of allowing an economic optimization of the energy output. In this study, the optimal economic and technical sizing of a lithium-ion battery, is analyzed by focusing on the day-ahead market profit maximization. This is done by scheduling the aleatory wind production using a 24-hours rolling horizon MILP optimization algorithm. The annual utilization profile and daily charge level are analyzed, and the related battery degradation is assessed. Finally, the battery cost is compared to the additional revenues, to assess the battery cost-optimal size in presence of battery degradation. The analysis is based on real Italian wind data and energy price time series

The role of diagnostic VATS in penetrating thoracic injuries

BACKGROUND: Penetrating chest injuries account for 1–13% of thoracic trauma hospital admissions and most of these are managed with a conservative approach. Nevertheless, 18–30% of cases managed only with tube thoracostomy have residual clotted blood, considered the major risk factor for the development of fibrothorax and empyema. In addition, 4–23% of chest injury patients present persistent pneumothorax and 15–59% present an injury to the diaphragm, which is missed in 30% of cases. In order to make a correct diagnosis, reduce the number of missed injuries, chronic sequelae and late mortality we propose performing surgical exploration of all patients with a penetrating injury of the pleural cavity. METHODS: 1270 patients who sustained thoracic trauma were admitted to our hospital between 1994 and 2004. Of these, 16 patients had penetrating injuries: thirteen were surgically explored by means of Video Assisted Thoracic Surgery (VATS), and 3 with thoracotomy due to hemodynamic instability or suspected lesion of the heart or great vessels. RESULTS: In the 13 patients who underwent VATS, 5 injuries to the diaphragm, 3 lesions to an intercostal artery, and 1 lesion to the diaphragmatic artery were detected. In 12 of these patients a laceration of the pulmonary parenchyma was also present. A conversion to thoracotomy was necessary due to a broad laceration of the diaphragm and due to hemostasis of an intercostal artery. In all but one case, which was later converted, diagnostic imaging missed the diagnosis of laceration of the diaphragm. There was no intra- or postoperative mortality, and average hospital stay was five days. CONCLUSION: VATS is a safe and effective way to diagnose and manage penetrating thoracic injuries, and its extensive use leads to a reduction in the number of missed, potentially fatal lesions as well as in chronic sequelae

Caracterización de etapas de perforado en probetas multicapas mediante la emisión acústica generada durante la perforación

Objective: This work is based on the Acoustic Emission (EA) monitoring of the cutting tool in a geological material drilling process and the use of Kohonen type Neural Networks for the classification of information. Methodology: The methodology consisted in the realization of a series of perforations on a specimen built with sandstone, limestone and slate rocks, arranged in layers and consolidated with a cement mixture. The tool used for drilling consisted of a double-edged Tungsten Carbide (CT) cutter, 65 mm in diameter. The entire process was monitored by an AE system coupled to the rotating drill and test specimen. Subsequently, the EA was correlated with the stratigraphy of the perforation, the information was processed and adapted to train and simulate a Kohonen type neural network, which classified the process information according to the type of rock that was traversed with the cutter. Results: The results show that the Acoustic Emission technique is sensitive to stratum changes during the drilling process of these geomaterials and that the instrumentation of the rotating drill provides a good monitoring channel for this process. In this, the change of interfaces of the interfaces and the stable drilling process can be observed through the analysis of acoustic emission parameters such as rms, MARSE energy, rise time and average frequency. Conclusions: The Acoustic Emission technique can be used to monitor the drilling process on this scale. The processing of the Acoustic Emission parameters allowed to train and simulate a Kohonen neural network that can classify different stages of the drilling process with a mixing error of less than 5%.Objetivo: El presente trabajo se basa en el monitoreo mediante emisión acústica de la herramienta de corte en un proceso de perforación de material geológico y la utilización de redes neuronales tipo Kohonen para la clasificación de la información. Metodología: La metodología consistió en la realización de una serie de perforaciones sobre una probeta construida con rocas tipo arenisca, caliza y pizarra, dispuestas en capas y consolidadas con una mezcla de cemento. El herramental utilizado para la perforación consistió en un cortador de dos filos de carburo de tungsteno (CT), de 65 mm de diámetro. El proceso completo fue monitoreado mediante un sistema de emisión acústica acoplado a la broca giratoria y a la probeta de ensayo. Posteriormente se correlacionó la emisión acústica con la estratigrafía de la perforación, se procesó y adaptó la información para entrenar y simular una red neuronal tipo Kohonen, que clasificó la información del proceso según el tipo de roca que se estaba atravesado con el cortador.   Resultados: Los resultados muestran que la técnica de emisión acústica es sensible a los cambios de estratos durante la perforación de estos geomateriales y que la instrumentación de la broca rotante brinda un buen canal de monitoreo de este proceso. En este se observan los transitorios de cambio de interfaces y el perforado estable mediante el análisis de parámetros de la emisión acústica como RMS, energía MARSE, rise time y frecuencia promedio. Conclusiones: La técnica de emisión acústica puede ser utilizada para el monitoreo del proceso de taladrado en la presente escala. El procesamiento de los parámetros de emisión acústica permitió entrenar y simular una red neuronal Kohonen que pueda clasificar diferentes etapas del perforado con un error de mezclado inferior al 5 %

Dispersion trading: an empirical analysis on the S&P 100 options

This study provides an empirical analysis back-testing the implementation of a dispersion trading strategy to verify its profitability. Dispersion trading is an arbitrage-like technique based on the exploitation of the overpricing of index options, especially index puts, relative to individual stock options. The reasons behind this phenomenon have been traced in literature to the correlation risk premium hypothesis (i.e., the hedge of correlations drifts during market crises) and the market inefficiency hypothesis. This study is aimed at evaluating whether dispersion trading can be implemented with success, with a focus on the Standard & Poor’s 100 options. The risk adjusted return of the strategy used in this empirical analysis has beaten a buy-and-hold alternative on the S&P 100 index, providing a significant over-performance and a low correlation with the stock market. The findings, therefore, provide an evidence of inefficiency in the US options market and the presence of a form of “free lunch” available to traders focusing on options mispricing