A General Simulation Framework for Supply Chain Modeling: State of the Art and Case Study

Nowadays there is a large availability of discrete event simulation software that can be easily used in different domains: from industry to supply chain, from healthcare to business management, from training to complex systems design. Simulation engines of commercial discrete event simulation software use specific rules and logics for simulation time and events management. Difficulties and limitations come up when commercial discrete event simulation software are used for modeling complex real world-systems (i.e. supply chains, industrial plants). The objective of this paper is twofold: first a state of the art on commercial discrete event simulation software and an overview on discrete event simulation models development by using general purpose programming languages are presented; then a Supply Chain Order Performance Simulator (SCOPS, developed in C++) for investigating the inventory management problem along the supply chain under different supply chain scenarios is proposed to readers.Comment: International Journal of Computer Science Issues online at http://ijcsi.org/articles/A-General-Simulation-Framework-for-Supply-Chain-Modeling-State-of-the-Art-and-Case-Study.ph

HC-290 (Propane) Vaporisation Inside a Brazed Plate Heat Exchanger

This paper presents the heat transfer coefficients measured during HC-290 (Propane) vaporisation inside a brazed plate heat exchanger: the effects of heat flux, saturation temperature (pressure) and outlet conditions are investigated. The heat transfer coefficients show weak sensitivity to saturation temperature (pressure) and great sensitivity to heat flux and outlet conditions. The saturated boiling experimental heat transfer coefficients are compared with two well-known equations for nucleate boiling (Cooper (1984) and Gorenflo (1993)). The mean absolute percentage deviation between experimental and calculated heat transfer coefficients is 26.9% and 16.6% for Cooper (1984) and Gorenflo (1993) equation respectively. The heat transfer measurement has been complemented with IR thermography in order to quantify the portion of the heat transfer surface affected by vapour super-heating

Extended stellar kinematics of elliptical galaxies in the Fornax cluster

We present extended stellar kinematics for a sample of 13 elliptical galaxies in the Fornax cluster. Major-axis velocity dispersion profiles (VDPs) and rotation curves (RCs) are given for 12 of the galaxies. A major feature of this data is the spatial extension: for 8 galaxies the data extends beyond 1 R_e, and for 5 it extends beyond 2 R_e. Compared to the previously available data, this corresponds to an increase in spatial coverage by a factor from 1 to 5. Five of the ellipticals in the sample turn out to be rotationally-supported systems, having positive rotation parameter log (V/sigma)*. One of these five, and another 3 galaxies from the remaining sample, display evidence for bar-like kinematics. The data indicate that the true number of `dynamically hot' stellar systems, is much lower than previously thought: of the Es in the present sample only 1/4 are confirmed as `pressure-supported' systems. The data reveal a host of individual peculiarities, like: wiggles, strong gradients, and asymmetries in the rotation curve and/or in the velocity dispersion profile, thus showing that the presence of kinematically distinct components and/or triaxiality is a common characteristic of this class of object.Comment: 27 pages, includes 15 eps figures. Accepted for publication in A&A Sup

design and simulation of two robotic systems for automatic artichoke harvesting

The target of this research project was a feasibility study for the development of a robot for automatic or semi-automatic artichoke harvesting. During this project, different solutions for the mechanical parts of the machine, its control system and the harvesting tools were investigated. Moreover, in cooperation with the department DISPA of University of Catania, different field structures with different kinds of artichoke cultivars were studied and tested. The results of this research could improve artichoke production for preserves industries. As a first step, an investigation on existing machines has been done. From this research, it has been shown that very few machines exist for this purpose. Based also on previous experiences, some proposals for different robotic systems have been done, while the mobile platform itself was developed within another research project. At the current stage, several different configurations of machines and harvesting end-effectors have been designed and simulated using a 3D CAD environment interfaced with Matlab®. Moreover, as support for one of the proposed machines, an artificial vision algorithm has been developed in order to locate the artichokes on the plant, with respect to the robot, using images taken with a standard webcam

Refrigerant R410A Vaporisation Inside a Small Brazed Plate Heat Exchanger

This paper presents the experimental heat transfer coefficients and pressure drop measured during refrigerant R410A vaporisation inside a small brazed plate heat exchanger: the effects of heat flux, refrigerant mass flux, saturation temperature and outlet conditions are investigated. The experimental results are reported in terms of refrigerant side heat transfer coefficients and frictional pressure drop. The heat transfer coefficients show high sensitivity both to heat flux and outlet conditions and weak sensitivity to saturation temperature. The frictional pressure drop shows high sensitivity to refrigerant mass flux and weak sensitivity both to saturation temperature and outlet conditions. The experimental heat transfer coefficients are also compared with two well-known correlations for nucleate pool boiling: a fair agreement is found

Energy and Economic Performance Analysis of Heat Recovery Devices Under Different Climate Conditions

High performance buildings typically relies on extreme envelope performances in terms of insulation level, solar gains valorization and airtightness. The energy needs are limited and the system sizing is reduced to increase the recourse to renewable energy sources. The only exception to this trend is related to the ventilation, which is even more crucial because of the infiltration control. Mechanical ventilation is a common option to ensure an appropriate ventilation rate and a suitable indoor air quality. Heat recovery devices are widely used to save energy in buildings mechanical ventilation systems. Their contribution in the design or operating phases is typically assessed in terms of effectiveness, which expresses the ratio between the amount of energy – sensible and/or total – actually recovered and the maximum recoverable under ideal configuration. However the effectiveness of recovery devices is not a constant value and depends on the operating – outdoor and indoor –conditions and control strategy. In order to evaluate the energy and cost savings allowed by heat recovery systems, these aspects have to be considered, and their relative impact on different heat recovery technologies accounted for. In this work, some of them are analyzed in detail and their contribution to the device effectiveness is discussed. The objective is to understand the influence of the air conditions (fresh and exhaust) on the energy savings considering different sensible and total heat recovery devices and operative constraints which could affect the control strategy. The analysis starts from hourly weather data, representative of different climate types, to quantify the actual effectiveness of different heat recovery systems. The impact of indoor conditions on the sensible and latent recovery is analyzed, defining appropriate control strategies to prevent excessive moisture recovery and discomfort issues when the indoor humidity is considered. Moreover, the effect of condensation and frosting on the hourly and annual performance of each kind of devices is analyzed. Three different climatic conditions have been considered. Sensible fixed-plate cross flow heat recovery system have been compared with enthalpy wheels By means of a parameterization of the operating constraints and the expression of the main quantities in specific terms, depending only on the building use, it has been possible to generalize the main results, making them independent of a specific case study, and to compare different technologies and climatic contexts. Seasonal and annual energy and economic performances have been quantified, as well as their sensitivity to specific calculation assumptions, such as the building type, the investment and energy costs, providing a synthetic overview of the technical and economic viability of the considered technologies and a geographic mapping of their competitiveness