Frequency and voltage partitioning in presence of renewable energy resources for power system (example: North Chile power network)

This paper investigates techniques for frequency and voltage partitioning of power network based on the graph-theory. These methods divide the power system into distinguished regions to avoid the spread of disturbances and to minimize the interaction between these regions for frequency and voltage control of power system. In case of required active and reactive power for improving the performance of the power system, control can be performed regionally instead of a centralized controller. In this paper, renewable energy sources are connected to the power network to verify the effect of these sources on the power systems partitioning and performance. The number of regions is found based on the frequency sensitivity for frequency partitioning and bus voltage for voltage partitioning to disturbances being applied to loads in each region. The methodology is applied to the north part of Chile power network. The results show the performance and ability of graph frequency and voltage partitioning algorithm to divide large scale power systems to smaller regions for applying decentralized controllers.Peer ReviewedPostprint (published version

Role of morphine preconditioning and nitric oxide following brain ischemia reperfusion injury in mice

Objective(s): Morphine dependence (MD) potently protects heart against ischemia reperfusion (IR) injury through specific signaling mechanisms, which are different from the pathways involved in acute morphine treatment or classical preconditioning. Since opioid receptor density changes post cerebral ischemia strongly correlated with brain histological damage, in the present study, we tried to elucidate the possible role of opioid receptors in IR injury among morphine-dependent mice. Materials and Methods: Accordingly, incremental doses (10 mg/kg/day to 30 mg/kg/day) of morphine sulphate were subcutaneously administered for 5 days before global brain ischemia induction through bilateral common carotid artery occlusion. Animals were received naloxone (5 mg/kg) or L-NAME (20 mg/kg) 30 min after the last morphine dose. Twenty four hr after the ischemia induction, Retention trial of passive avoidance test and western blot analysis were done. histological analysis (TUNEL and NISSL staining) performed 72 hr after ischemia. Results: MD improved post ischemia memory performance (P<0.01) and neuronal survival (P<0.001) and decreased apoptosis (P<0.05) in region I of hippocampus (CA1 region) in mouse. Treatment with naloxone or L-NAME abolished all MD aforementioned effects. Conclusion: Results of the present study suggested that opioid receptors activation in the early hr post ischemia is crucial for MD-induced hippocampus tolerance against IR injury. Opioid receptor-dependent balance of NO production was another key factor in MD-induced protection. Further studies are required to determine the effect of MD on opioid receptor changes after ischemia and its correlation with MD-induced protection. © 2015, Mashhad University of Medical Sciences. All rights reserved

Sulfur dioxide reduces hippocampal cells death and improves learning and memory deficits in rat model of transient global ischemia/reperfusion

Objective(s): According to recent the findings, sulfur dioxide (SO2) is produced by the cardiovascular system, influencing some major biological processes. Based on previous research, SO2 exhibits antioxidant effects and inhibits apoptosis following cardiac ischemia/reperfusion. Therefore, the objective of the current study was to examine the neuroprotective impact of SO2 following global cerebral ischemia/reperfusion (I/R). Materials and Methods: Forty-eight male Wistar rats that weighed 260�300 g, were randomly allocated into 4 groups: sham group (n=12), I/R group (n=12), and I/R+SO2 groups (NaHSO3 and Na2SO3; 1:3 ratio; 5 and 10 μg/kg, respectively; for 3 days, n=12). Cerebral ischemia model was prepared by occlusion of both common carotid arteries for 20 min. Saline as a vehicle and SO2 donor at doses 5 μg/kg (intraperitoneally) were injected for 3 days after reperfusion. Four days after ischemia, the passive avoidance memory test was carried out in four groups, and after behavioral assessment, necrosis, apoptosis, and antioxidant enzyme analysis were carried out. Results: SO2 treatment could significantly improve memory impairments in rats with cerebral ischemia/reperfusion (I/R) (P&lt;0.05). An increase in both superoxide dismutase and glutathione and a reduction in malondialdehyde were reported in the SO2 group versus the ischemic group (P&lt;0.05). Moreover, SO2 could significantly decrease necrotic and apoptotic cells in the CA1 region (P&lt;0.01). Conclusion: According to the findings, SO2 exerts significant neuroprotective effects on cerebral I/R due to its antioxidant activity. © 2018, Mashhad University of Medical Sciences. All rights reserved

Model of optimization of mining complex for the planning of flow of quarry production of limestone in multiple products and with elements for the analysis of the capacity

Activities in mining complexes contain multiple decisions that affect the operations of the system for the extraction, transformation, transport and storage of various subsoil components. The purpose of this research is the planning of continuous flow production systems for mixed products, in non-metallic mining extraction processes, considering bottlenecks and capacity planning. This paper presents a model for production, based on mathematical optimization, that facilitates the planning and management of operations in the area of extraction, crushing and transformation of a quarry of aggregates for construction, considering the resources and the constraints that allow to define effective strategies in the increase of the productivity of the lines of low production environment by scenarios. This research develops an analysis of bottlenecks and contrasts the nature of the production system by means of a mathematical model of optimization, which considers the capacities and balances in the flows of the Limestone production line. The mathematical model that maximizes profits can be adapted to systems of continuous flow production in mining complexes where their products are part of a reverse logistics process, analysis of alternatives of extraction, transformation and transport

Relationship between employee involvement and lean manufacturing and its effect on performance in a rigid continuous process industry

Relationship between employee involvement and lean manufacturing and its effect on performance in a rigid continuous process industry DOI: 10.1080/00207543.2014.975852 Juan A. Marin-Garciaa* & Tomas Bonaviab Received: 1 Aug 2013 Accepted: 30 Sep 2014 Published online: 04 Nov 2014 This research aims to empirically test the effect of employee involvement on lean manufacturing (LM), and the effect of LM on production outcomes. Employee involvement is operationalised through four related variables: empowerment, training, contingent remuneration and communication. The effects are tested by recording management perceptions in a different industrial sector from those usually studied in previous research ceramic manufacturers, a highly competitive and internationally successful sector. We obtained data from 101 ceramic tile plants (64% of response rate) in the Valencia region of Spain. This approach is developed using a statistical method called partial least squares. All paths are significant except for contingent remuneration; specifically, relationships were found between empowerment, training, communication and LM, and between LM and performance.This paper has been written with financial support from the Project "Path Dependence and decision-making for selecting LM tools and practices" (PAID-06-12-SP20120717) of the Universitat Politecnica de Valencia.Marín García, JA.; Bonavía Martín, T. (2015). Relationship between employee involvement and lean manufacturing and its effect on performance in a rigid continuous process industry. International Journal of Production Research. 53(11):3260-3275. https://doi.org/10.1080/00207543.2014.975852S32603275531

Optimal cooperation of a hydrogen storage system and fuel cell to supply electrical and thermal loads

A framework is planned to supply electrical and thermal loads by joint application of a hydrogen storage system (HSS) and a fuel cell. The system, including electrical and thermal loads, is connected to the upstream network. The bidirectional operation is defined for the system, and the system can buy energy from the grid or sell energy to the grid. A water electrolyzer is applied to produce hydrogen from water and store electricity in the form of hydrogen. The stored hydrogen supplies the thermal loads, as well as the fuel cell. The electrical loads are directly connected to the grid and are supplied by the grid. The electricity is received from the fuel cell at hours 17 to 22. When the price of electricity is high, the electrical loads can receive their power from the fuel cell rather than the grid. Additionally, any excess electricity may be sold to the grid. The uncertainty in the thermal and electrical loads is modeled and formulated as stochastic programming. The hydrogen is fed to the fuel cell and the thermal loads. The proposed model minimizes the daily operational cost of the system. The results demonstrate that the daily operational cost of the system is $22.274 USD/day. The bidirectional operation reduces the daily operational cost by about 79%. The unceratinty increases the cost by about 15%.Scopu