Extra Generation Research Articles

Volumetric entropy generation rate associated with tip clearance flow in linear cascade

The tip clearance flow structure and its corresponding entropy generation rate of a linear cascade with 1.85mm radial tip clearance operating under three different incidence angle are investigated. The incidence angle influences the tip leakage vortex position as well as the size of the tip leakage vortex. Larger incidence angle results in larger tip leakage vortex and pushes the tip leakage vortex further away from the suction side. The entropy generation rate related to the tip clearance flow structure is calculated and it is confirmed that tip clearance flow is the main major source of aerodynamic loss in linear cascade. Larger incidence angle leading to higher entropy generation rate. Results also show that it’s not the core region of tip leakage vortex but the edge vortex and shear layer of the tip clearance flow which has the highest entropy generation rate. When operating under an incidence angle of 4°, there exist an extra high entropy generation rate region in main flow. It is found that the compression and expansion of fluid due to the existence of tip clearance vortex was the main reason for this extra high entropy generation.

Ethylparaben induces subconjunctival fibrosis via the Wnt/β-catenin signaling pathway.

The aim of the present study was to explore the etiology of subconjunctival fibrosis (SCF) induced by ethylparaben, the most prevalent preservative in Chinese eye drops. Ethylparaben was administered to the left eyes of male Sprague-Dawley rats in the experimental group twice daily for 1 month, whereas the control group received PBS. Experimental group rats displayed a mild promotion in density of fibroblasts and a tighter deposition of collagen in the bulbar subepithelial connective tissue compared with the control group. Furthermore, the present findings revealed that extracellular matrix expression was promoted in murine bulbar conjunctival tissues in the experimental group. In primary conjunctival fibroblasts, expression of ECM triggered by ethylparaben was suppressed by XAV-939. Furthermore, stimulation of the Wnt/β-catenin axis triggered by ethylparaben was impaired by XAV-939. In conclusion, SCF triggered by ethylparaben results from extra ECM generation of conjunctival fibroblasts via the Wnt/β-catenin axis.

Copper doping effect on the properties in ZnO films deposited by sol–gel

In this work, an aqueous sol–gel route involving zinc acetate dihydrate and cupric chloride as precursors was used to obtain intrinsic and Cu-doped ZnO thin films onto SiO2/n-Si and glass substrates. Various concentrations of Cu ranging from 1 to 5% were used to modify the ZnO crystal structure. The effect of Cu-doping was evaluated by means of various microscopic and spectroscopic techniques. Scanning electron microscopy (SEM) proved increased grain density and evolution of grain shape from circular to hexagonal with Cu incorporation in the ZnO host lattice. Furthermore, atomic force microscopy (AFM) revealed that grain size increases with increasing Cu concentration. Moreover, X-ray diffraction (XRD) investigations reported a small influence of Cu-doping on the lattice constant value. However, Cu-doping level impacts the mean crystallite size, and consequently, the amount of dislocations emerging from the boundaries of the mosaic blocks. Finally, optical measurements proved the decrease of film transparency, as well as bandgap narrowing effect with increasing dopant concentration from 1 to 5%. As a result, copper incorporation into ZnO films using the proposed low-cost sol–gel method has the ability to tune the bandgap of ZnO-based materials and to promote extra charge carrier generation, which is highly beneficial for UV optoelectronic applications.

The Operational Space Formulation on Humanoids Considering Joint Stiffness and Bandwidth Limit

As the applications of robots increase, mobility and capability of interaction in unstructured environments have become important. Hence, humanoid robots have been developed to have these capabilities, and recently, compliant motions for safe contact have been studied. The Operational Space Formulation can be an effective method for humanoid robots to realize compliant motion via unified motion and force control. Nevertheless, the implementation of the Operational Space Formulation on humanoid robots has not been successful. One of the challenging issues is low position tracking performance. In this study, a control method for solving this problem is proposed by considering the joint stiffness and joint bandwidth limits. To consider joint stiffness, the Operational Space Formulation was derived using flexible joint robot dynamics. Additionally, an extra torque generation method, which penalizes low performance actuators, is utilized to account for the bandwidth limits. Neither methods requires additional sensors or joint space controllers. Hence, they can be useful for conventional humanoid robots composed of electric motors and gears. By integrating the two methods, the position tracking performance of the Operational Space Formulation on the humanoid robot was significantly improved. The proposed method was demonstrated via position and orientation control experiments using our humanoid robot, TOCABI.

On Farm Benefits of the Chickpea in Rajasthan with Reference to Gangour (GNG 1581) Variety

Chickpea (Cicer arientinum) is known in India since ancient times, and In Asia and Europe chickpea is said to be one of the oldest pulses known and cultivated. The On farm Benefits of the chickpea in Rajasthan with reference to Gangour (GNG 1581) variety was evaluated in this study. The evaluation was based on a household survey of chickpea grower in 4 villages of Bikaner District of Rajasthan. To evaluate on farm benefits of the chickpea in Rajasthan with reference to Gangour (GNG 1581) variety the cost of cultivation concept and simple statistical tools were used. Extra revenue generation estimated is ` 760 crores per year in case of Gangour (GNG 1581) variety. Labor productivity was higher for Gangour (GNG 1581) (0. 74q/day), and lower for the local variety (0.44q/day

Power generation cost minimization of the grid-connected hybrid renewable energy system through optimal sizing using the modified seagull optimization technique

A hybrid renewable power system is studied in this paper. This system is composed of PV panels, wind turbines, inverter, rectifier, electrolyzer, and fuel cell such that it prioritizes storing excess energy by converting it to hydrogen and using it later in the fuel cell. Additional extra generation power is sold to the main electricity network. The system generates power from clean sources and has zero emission. To achieve minimum power generation cost, the optimal size of each component is obtained using the proposed modified seagull optimization technique. The cooperative generation of wind and PV and energy storage mitigate the uncertain behavior of renewable energy sources. The proposed hybrid power system and optimization are implemented in a real-world case study in Qingdao, China. The consumption and meteorological data of the year 2018 are used as input to the system. To prove the superiority of the proposed optimization method in terms of accuracy and computation time, it is compared to two other optimization methods, namely original seagull optimization algorithm (SOA) and modified farmland fertility algorithm (MFFA), which are used in similar applications. The proposed method has achieved 2.02% and 2.78% better results and converged 69.36% and 47.07% faster compared to conventional SOA and MFFA methods, respectively. In addition, the hybrid system is able to operate with high reliability and loss of power supply probability well below the threshold of 8.96e20.

Impact of One- and Two-axis Solar Tracking on Techno-Economic Viability of On-Grid PV Systems: Case of Burnoye-1, Kazakhstan

Kazakhstan is currently committed to develop its renewable energy resources. In 2012, the government introduced a low-carbon energy strategy to reduce the production of air pollutants, including anthropogenic CO2e, and to increase the share of clean energy up to 50% of total consumption by 2050. As a contribution to this strategy, this paper presents a comparison in techno-economic performance of three scenarios. The differentiation will be between currently implemented fixed-slope on-grid PV power plants in Kazakhstan and proxy similar solar parks using one- or two-axis solar tracking systems. This paper aims to determine to what extent the more effective, but more expensive tracking systems might be a suitable standard in future PV power stations in the country. For this purpose, the existent fixed-slope 50 MWp Burnoye-1 commercial solar power plant located in Jambyl region, Kazakhstan, is used as a benchmark. As expected, solar panels with tracking systems produce more electricity year-round compared to those with fixed slopes. In comparison, one- and two-axis tracking systems led almost to the same amount of electricity export to the grid. Furthermore, despite the proxy PV power stations with one- and two-axis tracking technology could reduce around 10 ktCO2e emissions per year. This 25 to 29% and 33 to 33% ratio of extra-cost to extra-energy production, respectively, made both tracking scenarios not economically competitive compared to fixed panels. Nevertheless, if a tracking system has to be considered to further reduce GHG emissions and add extra annual electricity generation using current installed capacity of Burnoye-I, our results demonstrated that one-axis tracking should be preferred above two-axis system.

A numerical study of Vertical Axis Wind Turbine performances in twin-rotor configurations

Placing two counter-rotating rotors of a Vertical Axis Wind Turbine (VAWT) can lead to a significant power enhancement and a faster wake resorption. This global power output is directly related to the spacing between both rotors permitting a mutual confinement effect. In addition, the relative direction of angular velocity of both rotors can strongly impact the overall performances of the machine. A range of two-dimensional (2D) Unsteady Reynolds Averaged Navier-Stokes (URANS) simulations has been managed in order to study the aerodynamic interactions occurring in a pair of VAWT. By comparing with a single-rotor of VAWT, it has been shown than the global power enhancement of a double-rotor VAWT is linked with an extension of the lift production range in one of the two first quartiles of the upwind path. Moreover, the region of the extra power generation seems to be dependant on the relative rotational directions of counter-rotating rotors. In all cases, the extent of lift generation can be associated with a suppression of the cross-stream velocity induced by the confinement of the neighbouring turbine. This local flow perturbation, closed to the inner region, leads to an augmentation of the incidence experienced by the blades in the upwind path, increasing the global lift and torque recovered by the turbine.

Power management of grid-integrated energy storage batteries with intermittent renewables

Abstract Intensive charging and discharging modes of batteries cause an adverse effect on state of health of grid-integrated energy storage batteries (GIESBs). Furthermore, uncoordinated patterns of charging and discharging the GIESBs are able to expand voltage profiles of power grids beyond their limits, while considering extra generation from photovoltaic arrays (PVs) and wind turbines (WTs). Therefore, a decentralized power management scheme is proposed in this paper to mitigate such impact on grid voltages and to improve the performance of the GIESBs with PVs and WTs. The proposed scheme develops three clusters of different objective functions to coordinate charging and discharging cycles of the GIESBs based on mixed integer linear programming, considering state of charge (SoC) and depth of discharge (DoD) of the batteries. The first cluster minimizes the power-charging cost of the GIESBs by utilizing time of use tariffs. The second cluster minimizes the charging power of the GIESBs, employing per unit generation from PVs and WTs, whereas the third cluster minimizes the discharging power of the GIESBs, using per unit consumption of residential loads. Simulation results of six scenarios show that, although the proposed scheme of the first cluster reduces operational costs of the GIESBs, it cannot maintain system voltages within the limitations. With the second and third clusters, the proposed scheme exhibits a better performance in stabilizing grid voltages, while maintaining the SoC and DoD within their boundaries to underpin state of health of the batteries.

Space-Time Modulation: Principles and Applications

The ever-increasing demand for high-datarate wireless systems has led to a crowded electromagnetic (EM) spectrum. This demand has successively spurred the development of versatile microwave and millimeter-wave integrated components possessing high selectivity, multifunctionalities, and enhanced efficiency. These components require a class of nonreciprocal structures endowed with extra functionalities, e.g., frequency generation, wave amplification, and full-duplex communication. Space-time (ST) modulation has been shown to be a perfect candidate for high-data-rate transmission given its extraordinary capability for EM-wave engineering. ST-modulated (STM) media are dynamic, directional EM structures whose constitutive parameters vary in both space and time.

Facilitating high levels of wind penetration in a smart grid through the optimal utilization of battery storage in microgrids: An analysis of the trade-offs between economic performance and wind generation facilitation

The aim of this paper was to investigate the trade-offs that can be achieved between optimizing the electricity costs of a building integrated microgrid, while simultaneously facilitating high levels of wind penetration in a smart grid. This study applied multi-objective optimization to obtain a daily charge and discharge schedule of a battery bank, which was used to store electricity from the microgrid and smart grid and could also provide electricity to the building and smart grid. Multi-objective optimization was employed due to the independent objectives of minimizing building operating cost and maximizing the facilitation of wind energy from the smart grid. The trade-offs between the two objectives were simulated, evaluated and analyzed. A priority weighting factor (α) was applied to each objective. The purpose of α was to vary the importance of each objective relative to the other in an inversely proportional manner. This enabled the algorithm to optimize the battery operating schedule for the economic performance of the microgrid, the facilitation of wind generation from the smart grid or for trade-offs in between. The results present a comprehensive evaluation of 96 scenarios with varying daily weather conditions, building electricity demand, electricity pricing, microgrid output and wind penetration from the smart grid. A multi-objective optimization approach was then applied for each of the 96 scenarios with 11 α values to determine optimal trade-offs in these scenarios. Generally for the 96 scenarios analyzed, when the α value was 20% or higher, the amount of extra wind generation facilitation obtained was negligible while microgrid operating costs continued to increase. The results showed that when changing from an α value of 0% to an α value of 20%, there was a large increase in wind generation facilitation compared to the corresponding increase in cost, with wind generation facilitation increasing from its minimum value to within 89% of its maximum value (10.7% to 14.3% of facilitated wind generation). The corresponding building cost increased from its minimum value to within 13% of its maximum value (€1.14/day to €1.37/day). This produced a cost of approximately €0.06 for every 1% increase in wind generation facilitation. In comparison to this, changing from an α value of 20% to an α value of 100% implied a cost of approximately €3.64 for every 1% increase in wind generation facilitation. These results indicated that smart grids with large percentages of wind penetration may be substantially aided by utilizing the storage capacity of building integrated microgrids for a relatively low monetary cost.

Low-dose curcumin reduced TNBS-associated mucin depleted foci in mice by scavenging superoxide anion and lipid peroxides, rebalancing matrix NO synthase and aconitase activities, and recoupling mitochondria.

The role of mitochondrial dysfunction in the pathogenesis of inflammatory bowel diseases (IBD) is still being investigated. This study evaluated the therapeutic effect of curcumin (Cur), a polyphenolic electrophile in 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced chronic colitis and mitochondrial dysfunction, in mice. Colitis was induced by rectal instillation to mice of 30mgkg-1 TNBS, alone or followed by daily intraperitoneal injections of Cur 25mgkg-1. Animals were euthanized at days 3, 7, and 14, post TNBS challenge. Colon mitochondria of control mice were treated with 5µM Cur, and TNBS (50, 100µM)-toxicity was evaluated by measuring swelling, respiration, and aconitase and fumarase activities. Redox status was evaluated in colon mucosa and in mitochondria. In vitro, a short-term Cur treatment controlled the dose and time dependent mitochondrial toxicity induced by TNBS, by collapsing the generation of superoxide anion and hydroperoxy lipids, rebalancing nitric oxide synthase and aconitase activities, and recoupling mitochondria. In vivo, a daily low-dose Cur abolished mice mortality which reached 27% in model group. Cur improved in a time dependent manner mucosal redox homeostasis, cell apoptosis, mucin depleted crypts and crypt abscesses by controlling prooxidant activity of myeloperoxidase and NO synthase associated to phagocytes influx, quenching hydroperoxy lipids, and reboosting GSH levels. Cur, by quenching intra and extra mitochondrial ROS generation, rebalancing aconitase/fumarase and MDA/GSH ratios, and recoupling mitochondria, may support mithormesis priming and remitting in IBD.

USES OF MIGRANTS’ REMITTANCES IN THE HOME COUNTRY: FOCUSING ON THE CASE OF PAKISTANI LABOR MIGRANTS IN SOUTH KOREA

This research paper has elucidated important factors and international remittance utilization areas in Pakistan. Due to the political and economic situation of the country, the people migrate to developed countries to earn better living standards for themselves and, the left-behind families. As of 2018, the Bureau of Immigration & Overseas Employment, Government of Pakistan counts 15472 Pakistanis living in South Korea. In a bid to fully conduct this research, the structured interviews are conducted with Pakistani labor migrants residing in district Gwangju, South Korea. During the interview, participants are asked about the migration process, difficulties in the settlement, working environment, and volume of monthly remittances sent to their home country. The main purpose of the study is to investigate the current situation of Pakistani labor migrants in South Korea and to explore how their remittances are being utilized by their family members in Pakistan. Pakistani labor migrants are migrating to Korea through the Bureau of Immigration & Overseas Employment, Government of Pakistan, to work in Korean factories. The observed motive of migration is the income generation that is utilized to improve the living standard of their families in Pakistan. As this study shows, transfer remittances are used to cover daily living expenses such as food, health, education, and other emergency needs such as medical, marriages, and funerals. The part of the transfer remittance is also used to establish a business in their home country for extra income generation and creation of employment opportunities for local people. Prior to the migration, the migrants learned the basic level of Korean language skills from their home country, but these skills did not reduce their difficulty in communication. The most prominent problem being faced by the migrants is the unavailability of halal food which is very important regarding their religious beliefs. Key words: Remittance, development, income, labor migrants, remittance utilization areas.

Integrated Scheduling of Hybrid Generation and Demand Response Program for a Building

This paper illustrates a comprehensive model of an energy management system and a novel control algorithm in a building in a grid-connected state. This study attempts to provide an approach including a proposed scheduling algorithm and a hybrid model of electricity generation to reduce the electricity consumption cost and increase the reliability of the grid in summer due to the great demands of electricity for using air condition systems. The model consists of cogeneration of a photovoltaic system and a diesel generator with a battery storage system. The electrical consumption profile of home appliances used in the daytime is modeled. Then an algorithm is introduced to observe and schedule the electrical appliances and charge and discharge the batteries in an optimal way. The results depict that the unified model and proposed control strategy are performed successfully and the peak of electrical demand is eliminated appropriately. The occupants also can benefit financially in grid-connected mode by selling extra domestic electricity generation to the grid over the peak time period.

Dynamic Frequency and Overload Management in Autonomous Coupled Microgrids for Self-Healing and Resiliency Improvement

Autonomous microgrids (MGs) are being installed in large remote areas to supply power where access to the utility grid is unavailable or infeasible. The power generation of such standalone MGs is largely dominated by renewable based energy sources where overloading or power deficiencies can be common due to the high intermittency and uncertainty in both load and power generation. Load-shedding is the most common mechanism to alleviate these problems to prevent system instability. To minimize load-shedding, most MGs are equipped with local battery energy storage (BES) systems to provide additional support. Furthermore, in the event of severe overloading or when BES capacity is insufficient to alleviate the overload, neighboring MGs can be provisionally coupled to provide mutual support to each other which is a more effective, economic and reliable approach. Such a coupling is preferred to be via power electronic converters to enhance the autonomy of the MGs. This paper proposes a two-stage, coordinated power sharing strategy among BESs and coupled MGs for overload management in autonomous MGs, through dynamic frequency control. Both local BES and the neighboring MGs can work in conjunction or individually to supply the required overload power demand. For this, BES' state of charge should be above a minimum level and extra power generation capacity needs to be available in the neighboring MGs. A predefined framework with appropriate constraints and conditions, under which the power exchange will take place, are defined and formulated. The proposed mechanism is a decentralized approach, operating based on local frequency and state of charge measurements, and without any data communication amongst the MGs. The dynamic performance of such a network, is evaluated through extensive simulation studies in PSIM R and verifies that the proposed strategy can successfully alleviate the overloading situation in the MGs through proper frequency regulation.

Accommodating uncertain wind power investment and coal-fired unit retirement by robust energy storage system planning

Increasing wind power integration and coal-fired unit retirement strain the power system's spinning reserve and increase the pressure on peak regulation. With the ability to stock extra power generation and supply the peak load, the energy storage system (ESS) can alleviate the rising demand on the spinning reserve and plays an increasingly important role in the power system. In this paper, a tri-level robust ESS planning model is proposed to accommodate uncertain wind power investment as well as coal-fired unit retirement. The upper-level of this model is to determine the planning scheme of ESSs, which iteratively takes the worst-case of wind power investment and coal-fired unit retirement into consideration. The middle-level and lower-level of this model are to make the optimal daily economic dispatch under the worst-case realizations of uncertainties. We derive an equivalent reformulation of the proposed robust ESS planning model and solve it with a dual column-and-constraint generation algorithm. Case studies are conducted on the IEEE RTS-79 system. The results demonstrate the superiority of the proposed planning method in comparison with other methods. Furthermore, the effects of the capital cost of ESS, the expected proportion of wind power, and the uncertainty budget on the development of ESS are studied. Taking the uncertainties of unit retirement and wind power investment into consideration achieves a better trade-off between the ESS investment cost and the operation cost.

Assessment of standalone solar PV-Battery system for electricity generation and utilization of excess power for water pumping

This study presents a developed assessment methodology for Photovoltaic-Battery power system featured with utilization of the dumbed power for secondary applications such as water pumping. Primary target is to meet the demand of 3.2 kWh/day for rural housing unit. The PV-Battery system size is determined by varying the number of PV’s and Battery capacity. At each configuration, having the Loss of Power Supply Probability of 0, the Levelized Cost of Energy is determined. It has been revealed that the number of PV panels are depending on a day with lowest solar irradiations. However, the required battery storage is contingent on the maximum number of hours the battery is required to supply power to the load. In the present study, the battery can supply power for maximum of 16 h such as starting from 4:00 PM to 7:00 AM next day. The selected size of PV-Battery system to meet the load demand of 3.2 kWh/day and utilize the excess power for water pumping consists of 2.44 kWp of PV’s and 3.55 kWh of installed battery capacity. The selected power system generates an average 9.807 kWh/day and provides the water pumping of 363 m3/day. The power yield in peak hours and Levelized Cost of Energy are 58.6% and 0.3750 $/kWh, respectively. It is reviled that the excess power is unavoidable, and it is recommended to be utilized for water pumping. If the water is pumped to elevated storage, it may be used for extra hydro power generation by hybrid PV-Battery-Hydro power.

Advanced methodology for wind resource assessment near hydroelectric dams in complex mountainous areas

To increase renewable energy generation in some hydroelectric dams, a solution consisting in installing wind turbines close to dams is proposed. Indeed, dam surroundings are prone to benefit from wind speed-up effect, extra wind generation associated with thermal winds, and existing electrical infrastructure. Identifying the most suitable locations for turbines, that is, areas of relatively high-speed and low-turbulence wind, is fundamental to maximize this complementary power. Easy accessibility to turbines and minimum distance to dam electrical infrastructure are also essential to reduce the costs. Thus, a methodology is proposed to improve wind resource assessment in complex mountainous areas. First, potentially interesting dams are chosen using statistical local wind data. Second, weighted results of wind speed and turbulence intensity, considering all wind directions are presented based on CFD simulations. Finally, wind power density and annual energy production maps are generated, along with accessibility maps, to identify suitable sites. The Camarasa dam in the north-east of the Iberian Peninsula is chosen as case study to show and test the proposed methodology. Error estimations are provided, along with validation against Wind Atlas data and WAsP simulations.

Prediction the data consumption for power demands by elman neural network

The load forecasting consider as part important in power system operation. The exact prediction for power demand is important for planning how much need extra power generation to cover extra load to keep without happen shutdown. Neural networks stay frequently designed for modeling dynamic processes. The Multi-Layer Perceptron (MLP) with Radial Basis Functions (RBF) network is static approximations used fewer frequently in the discrete-time domain. In this paper proposed predict method for daily peak load by Elman Neural Network (ENN) with using data power demand for 2 years collected from National Control Center (NCC) and comparing the result. The result show the proposal is evaluated and followed the power demand.

A Heuristic Approach to the Post-Disturbance and Stochastic Pre-Disturbance Microgrid Formation Problem

Microgrid formation is a potential solution in post-disaster electric grid recovery efforts. Recent works propose distribution level microgrid formation models using mixed-integer linear programming techniques. However, these models can only be solved for small and medium size power systems due to their computational intractability. In this paper, we introduce a heuristic approach to approximately solve the post-disturbance microgrid formation problem for medium to large, more realistic, instances. Furthermore, the proposed approach allows to approximately solve the pre-disturbance microgrid formation problem (a stochastic version of the post-disturbance problem), in which the aim is to allocate extra generation capacity to the network to immunize it, as best as possible, against an uncertain cascading failure. Our results are illustrated by solving versions of the problem on ten test cases with up to 3012 buses.