Market power appearance through game theoretic maintenance scheduling of distributed generations

The oligopoly structure of the market and the network constraints may produce results far from the perfect competition. Maintenance decisions in an oligopolistic electricity market have a strategic function, because GENCOs usually have impacts on market prices through capacity outages. This paper describes generation maintenance planning in an oligopolistic environment as a strategic decision. In this paper a game theoretic framework is modeled to analyze strategic behaviors of GENCOs. Each GENCO tries to maximize its payoff by strategically making decisions, taking into account its rival GENCOs' decisions. Some GENCOs own DG units, such as wind, diesel, biomass and fuel cell plants. If different GENCOs find out they have the conditions of exerting market power exact in maintenance periods; they will share their data and they will cause some area monopolies. Cournot-Nash equilibrium is used for decision making on maintenance problem in Oligopolistic electricity market. The Cournot-Nash problem is modeled as a mixed integer nonlinear programming optimization problem. The analytic framework presented in this paper enables joint assessment of maintenance and generation strategies. © 2011 Praise Worthy Prize S.r.l. -All rights reserved

Effect of air pollution on onset of acute coronary syndrome in susceptible subgroups

While long-term exposure to air pollutants is associated with an increase in heart diseases and mortality, little information is available about the short-term effects of air pollution. This case-crossover study assessed the relationship of particulate matter (PM10) and carbon monoxide (CO) levels with hospital admission for acute coronary syndrome in Tehran, Islamic Republic of Iran. We interviewed 250 patients with a first episode of acute coronary syndrome and obtained data from hospital records and Tehran Air Quality Control Company. The risk of acute coronary syndrome was significantly associated with elevated concentrations of CO the day before the event (OR 1.18; 95% CI: 1.03-1.34) but not significantly with PM10 (OR 1.00; 95% CI: 0.99-1.02). Stratification by age, sex, diabetes, hypertension and smoking status did not affect the results, but women were more susceptible than men to CO levels (OR for women/men 1.68; 95% CI: 1.25-2.26)

Evolutionary dynamics on any population structure

Evolution occurs in populations of reproducing individuals. The structure of a biological population affects which traits evolve. Understanding evolutionary game dynamics in structured populations is difficult. Precise results have been absent for a long time, but have recently emerged for special structures where all individuals have the same number of neighbors. But the problem of determining which trait is favored by selection in the natural case where the number of neighbors can vary, has remained open. For arbitrary selection intensity, the problem is in a computational complexity class which suggests there is no efficient algorithm. Whether there exists a simple solution for weak selection was unanswered. Here we provide, surprisingly, a general formula for weak selection that applies to any graph or social network. Our method uses coalescent theory and relies on calculating the meeting times of random walks. We can now evaluate large numbers of diverse and heterogeneous population structures for their propensity to favor cooperation. We can also study how small changes in population structure---graph surgery---affect evolutionary outcomes. We find that cooperation flourishes most in societies that are based on strong pairwise ties.Comment: 68 pages, 10 figure

Comparing the effect of Toll-like receptor agonist adjuvants on the efficiency of a DNA vaccine

We have investigated whether poly(I:C) Toll-like receptor 3 (TLR3) and resiquimod Toll-like receptor 7 (TLR7) agonists can serve as vaccine adjuvants and promote the efficiency of therapeutic DNA vaccination against tumors expressing the human papilloma virus 16 (HPV-16) E7 protein. For this purpose, C57BL/6 mice were inoculated with 2 × 105 TC-1 cells, and they were then immunized with HPV-16 E7 DNA vaccine alone or with 50 μg of resiquimod or poly(I:C) individually. We found that poly(I:C) and resiquimod could induce more antigen-specific lymphocyte proliferation and cytolytic activity compared to vaccination with E7 DNA alone. While E7 DNA had no significant inhibitory effect on tumor growth, co-administration of poly(I:C) and resiquimod with E7 DNA induced significant tumor regression. Peripheral and local cytokine assays demonstrated that co-administration of poly(I:C) and resiquimod with E7 DNA induced circulating antigen-specific IFN-γ and nonspecific intratumoral IL-12. TLR3 and TLR7 agonists can be used to enhance the immune response to DNA vaccine immunogens. Taken together, these data indicate that combined vaccination with DNA encoding HPV-16 E7 plus TLR agonists provides a strategy for improving the efficacy of a vaccine as a possible immunotherapeutic strategy for cervical cancer. © 2014 Springer-Verlag Wien

Investigating the pre-damaged PZT sensors under impact traction

Ships are usually under vibration, impact, and other kinds of static and dynamic loads. These loads arise from water flow across the hull or surfaces, the propeller cavitation, and so on. For optimal design purposes and reliable performance, experimental measurements are necessary. These sensors are often used under or near the water, working conditions that improve the risk of sensor damage. This paper aims at investigating, by the use of finite elements, the behavior of damaged piezoelectric sensors under traction and impact loads. The numerical method was calibrated using results available in the literature regarding piezoelectric and elastic plates with a central crack. After calibration, the simulation was used on two types of Lead-Zirconium-Titanium oxide (PZT) sandwich panel structures reinforced by aluminum skins. The results proved that the damage size and impact energy are important factors affecting the response of piezoelectric sensors; therefore, special attention might be considered when using these sensors for marine applications

Transmission constraints impacts on monopolistic production capacity under strategic bidding

In power systems, transmission network constraints and losses can introduce gross distortions in the market for electrical energy. Congestion occurs frequently in weakly connected networks and may split a market into regions unable to compete properly with each other. The oligopoly structure of the market and the network constraints may produce results far from the perfect competition. This may cause lack of cheap energy in some areas and surplus in others. Consideration of market power caused by congestion is the main aids of our paper. We have used a methodology in order to evaluate any events that are suspected to have any relation to the market power. Since some participants have the ability to raise prices without losing market share, we should identify them and determine the amount of this energy. Bidding strategies, such as withholding capacity and bidding at higher price, influence the network and cause transmission congestion. The methodology was tested on IEEE 30 buses standard system by some indices such as HHI and Lerner index, finally the results of identification have been confirmed. For this simulation MATPOWER version 3.2 was used as OPF solver using both AC and DC power flow representation

Shape-adaptive metastructures with variable bandgap regions by 4D printing

This article shows how four-dimensional (4D) printing technology can engineer adaptive metastructures that exploit resonating self-bending elements to filter vibrational and acoustic noises and change filtering ranges. Fused deposition modeling (FDM) is implemented to fabricate temperature-responsive shape-memory polymer (SMP) elements with self-bending features. Experiments are conducted to reveal how the speed of the 4D printer head can affect functionally graded prestrain regime, shape recovery and self-bending characteristics of the active elements. A 3D constitutive model, along with an in-house finite element (FE) method, is developed to replicate the shape recovery and self-bending of SMP beams 4D-printed at different speeds. Furthermore, a simple approach of prestrain modeling is introduced into the commercial FE software package to simulate material tailoring and self-bending mechanism. The accuracy of the straightforward FE approach is validated against experimental observations and computational results from the in-house FE MATLAB-based code. Two periodic architected temperature-sensitive metastructures with adaptive dynamical characteristics are proposed to use bandgap engineering to forbid specific frequencies from propagating through the material. The developed computational tool is finally implemented to numerically examine how bandgap size and frequency range can be controlled and broadened. It is found out that the size and frequency range of the bandgaps are linked to changes in the geometry of self-bending elements printed at different speeds. This research is likely to advance the state-of-the-art 4D printing and unlock potentials in the design of functional metastructures for a broad range of applications in acoustic and structural engineering, including sound wave filters and waveguides

Validity of noncycloplegic refraction in the assessment of refractive errors: the Tehran Eye Study

Purpose: To determine the sensitivity and specificity of noncycloplegic autorefraction for determining refractive status compared to cycloplegic autorefraction. Methods: The target population was noninstitutionalized citizens of all ages, residing in Tehran in 2002, selected through stratified cluster sampling. From 6497 eligible residents, 70.3% participated in the study, from August to November 2002. Here, we report data on 3501 people over the age of 5 years who had autorefraction with and without cycloplegia (two drops of cyclopentolate 1.0% 5 min apart, with autorefraction 25 min after the second drop). Results: Overall, the sensitivity of noncycloplegic autorefraction for myopia was 99%, but the specificity was only 80.4%. In contrast, the sensitivity for hyperopia was only 47.9%, but the specificity was 99.4%. At all ages, noncycloplegic autorefraction overestimated myopia and underestimated hyperopia. Overestimation of myopia was highest in the 21-30 and 31-40 year groups. Underestimation of hyperopia was high up to the age of 50 (20-40%), but decreased with age, to about 8% after the age of 50, down to almost 0% after 70. The difference in mean spherical equivalent with and without cycloplegia fell from 0.71 dioptres (D) in the 5-10 age group to 0.14D in those over 70. Conclusion: Use of noncycloplegic autorefraction in epidemiological studies leads to considerable errors relative to cycloplegic measurements, except in those over 50-60. The difference between cycloplegic and noncycloplegic measurements varies with age and cycloplegic refractive category, and there is considerable individual variation, ruling out adjusting noncycloplegic measurements to obtain accurate cycloplegic refractions